Particularly dangerous situation

In weather forecasting in the United States, "particularly dangerous situation" (PDS) is enhanced wording used by the National Weather Service to convey special urgency in some watch or warning messages for unusually extreme and life-threatening severe weather events, above and beyond the average severity for the type of event. It is used in the format "This is a particularly dangerous situation..." at the discretion of the issuing forecaster. A watch or warning bearing the phrase is referred to as a PDS watch or PDS warning as shorthand jargon.

It was first used by the Storm Prediction Center (SPC), a national guidance center of the National Weather Service, for tornado watches and eventually expanded to use for other severe weather watches and warnings by the agency's regional forecast offices. It is most commonly used for major tornado outbreaks or long-lived, extreme derecho events, and has been used for non-convective weather hazards such as exceptional flash flooding, or a wildfire. ^{[1] [2]}

PDS watches and warnings alike are quite uncommon; less than 3% of watches issued by the SPC from 1996 to 2005 were PDS watches, or an average of 24 each year. ^[3] When a PDS watch is issued, there are often more PDS watches issued for the same weather system, even on the same day during major outbreaks, so the number of days per year that a PDS watch is issued is significantly lower.

Background

The short history of the origin of the option of issuing a tornado watch with the enhanced PDS wording occurred during the winter of 1981–82 when the Severe Local Storms (SELS) unit transitioned to a more flexible method of issuing weather products. Ed Ferguson, Deputy Director of the National Severe Storms Forecast Center (NSSFC), suggested to Lead Forecaster Jack Hales that the guidance center could provide an opportunity to give more resolution to the tornado watch product. Hales suggested the PDS option to identify areas where, a few times each year, conditions are most likely to aid in the development of large and intense tornadoes. The first PDS tornado watch was issued by Robert H. Johns for the April 2, 1982 tornado outbreak across the southern and central Great Plains. ^[4]

While historically applied only to severe thunderstorm, tornado and flash flood watches (i.e., severe local storm "polygonal" events), PDS wording could theoretically be applied to other types of weather watches (such as winter storm, high wind, hurricane, or fire weather watches) when an enhanced threat for such conditions exists. These watches have generally (but not always) been issued during a high risk or an upper-end moderate risk either of severe storms from the SPC's convective outlooks or of flash flooding from the Weather Prediction Center (WPC)'s excessive rainfall outlooks.

On April 24, 2011, the National Weather Service Weather Forecast Office in Memphis, Tennessee, issued the first PDS flash flood watch to highlight the threat for widespread, significant and potentially life-threatening flash flooding due to repeated rounds of severe thunderstorms.

On December 19, 2017, and August 3, 2018, the National Weather Service Weather Forecast Office in Reno, Nevada, issued PDS red flag warnings to highlight the threat for potentially life-threatening fire danger due to strong gusty winds and low humidity.

Issuance

PDS flash flood watch

PDS flash flood watches are issued when there is a higher-than-normal risk of widespread, life-threatening flash flooding. These watches are issued by local NWS Weather Forecast Offices, not the Storm Prediction Center.

Below is the first PDS flash flood watch, which was issued by the National Weather Service Forecast Office in Memphis, Tennessee, on April 24, 2011, as mentioned above. ^[5]

PDS flash flood watch

URGENT - IMMEDIATE BROADCAST REQUESTED  FLOOD WATCH  NATIONAL WEATHER SERVICE MEMPHIS TN  239 PM CDT SUN APR 24 2011    ...VERY HEAVY RAINFALL THROUGH THE MIDDLE OF THIS WEEK WILL LIKELY  LEAD TO SIGNIFICANT...WIDESPREAD FLASH FLOODING...    ...THIS IS A PARTICULARLY DANGEROUS SITUATION...    A BOUNDARY WILL CONTINUE TO REMAIN STATIONARY ACROSS SOUTHERN  MISSOURI INTO KENTUCKY THROUGH MONDAY. REPEATED ROUNDS OF  THUNDERSTORMS WILL TRACK ALONG THE FRONT BRINGING HEAVY RAINFALL.  THEN A LOW PRESSURE SYSTEM WILL TRACK ALONG IT INTO MISSOURI AND  PUSH THE FRONT FURTHER SOUTH TO ALONG THE I-40 CORRIDOR MONDAY  NIGHT THROUGH TUESDAY NIGHT. THIS WILL SHIFT THE HEAVY RAIN AXIS  FURTHER SOUTH TO ALONG AND JUST NORTH OF THE I-40 CORRIDOR.    A SECOND LOW PRESSURE SYSTEM WILL TRACK ALONG THE NEWLY STALLED  BOUNDARY AND SET OFF ADDITIONAL TRAINING THUNDERSTORMS LATE  TUESDAY NIGHT AND WEDNESDAY. THE FINAL COLD FRONT WILL PASS  THROUGH LATE WEDNESDAY AFTERNOON...ENDING THE PERSISTENT HEAVY  RAINFALL.    ARZ026>028-035-036-048-049-058-MSZ001>014-TNZ003-004-019>021-  048>055-088>092-250400-  /O.NEW.KMEG.FF.A.0007.110426T0000Z-110428T0000Z/  /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/  CRAIGHEAD-POINSETT-MISSISSIPPI-CROSS-   CRITTENDEN-ST. FRANCIS-  LEE AR-PHILLIPS-DESOTO-MARSHALL-BENTON MS-TIPPAH-ALCORN-  TISHOMINGO-TUNICA-TATE-PRENTISS-   COAHOMA-QUITMAN-PANOLA-LAFAYETTE-     UNION-WEAKLEY-HENRY-DYER-GIBSON-CARROLL-LAUDERDALE-TIPTON-HAYWOOD-  CROCKETT-MADISON-CHESTER-HENDERSON-   DECATUR-SHELBY-FAYETTE-  HARDEMAN-MCNAIRY-HARDIN-  INCLUDING THE CITIES OF...JONESBORO...HARRISBURG...BLYTHEVILLE...  WYNNE...WEST MEMPHIS...FORREST CITY...HELENA...   SOUTHAVEN...  OLIVE BRANCH...CORINTH...IUKA...TUNICA...BOONEVILLE...  CLARKSDALE...BATESVILLE...OXFORD...NEW ALBANY...  MARTIN...  DRESDEN...PARIS...DYERSBURG...HUMBOLDT...MILAN...HUNTINGDON...  COVINGTON...JACKSON...LEXINGTON...BARTLETT...GERMANTOWN...  COLLIERVILLE...MEMPHIS...MILLINGTON...SOMERVILLE...   BOLIVAR...  SAVANNAH  239 PM CDT SUN APR 24 2011    ...FLASH FLOOD WATCH IN EFFECT FROM MONDAY EVENING THROUGH  WEDNESDAY EVENING...    THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A    * FLASH FLOOD WATCH FOR PORTIONS OF EAST ARKANSAS...NORTH MISSISSIPPI  AND WEST TENNESSEE...INCLUDING THE FOLLOWING AREAS...IN EAST  ARKANSAS...CRAIGHEAD...CRITTENDEN...CROSS...  LEE...MISSISSIPPI...PHILLIPS...POINSETT AND ST. FRANCIS. IN  NORTH MISSISSIPPI...ALCORN...BENTON...COAHOMA...DESOTO...  LAFAYETTE...MARSHALL...PANOLA...PRENTISS...QUITMAN...TATE...  TIPPAH...TISHOMINGO...TUNICA AND UNION. IN WEST TENNESSEE...  CARROLL...CHESTER...CROCKETT...DECATUR...DYER...FAYETTE...  GIBSON...HARDEMAN...HARDIN...HAYWOOD...HENDERSON...HENRY...  LAUDERDALE...MADISON...MCNAIRY...SHELBY...TIPTON AND WEAKLEY.    * FROM MONDAY EVENING THROUGH WEDNESDAY EVENING.  * THIS IS A PARTICULARLY DANGEROUS SITUATION  * TOTAL RAINFALL AMOUNTS OF 5 TO 8 INCHES ARE EXPECTED ALONG AND  NORTH OF I-40 WITH 2 TO 5 INCHES EXPECTED SOUTH OF I-40. LOCALLY  HIGHER AMOUNTS ARE LIKELY.    * RAINFALL AMOUNTS SUCH AS THESE MAY LEAD TO WIDESPREAD...  SIGNIFICANT...AND LIFE THREATENING FLASH FLOODING. THIS EVENT  MAY BE AS SEVERE AS THE MAY 1–2, 2010 FLOODING IN PLACES. FLASH  FLOODING OF CITIES...RURAL AREAS...RIVERS...AND SMALL STREAMS  ARE POSSIBLE.    PRECAUTIONARY/PREPAREDNESS ACTIONS...    A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD  TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.    YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION  SHOULD FLASH FLOOD WARNINGS BE ISSUED.    &&    $$    ARZ008-009-017-018-MOZ113-115-TNZ001-002-250400-  /O.EXT.KMEG.FF.A.0006.000000T0000Z-110428T0000Z/  /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/  RANDOLPH-CLAY-LAWRENCE-GREENE-DUNKLIN-PEMISCOT-LAKE-OBION-  INCLUDING THE CITIES OF...WALNUT RIDGE...PARAGOULD...KENNETT...  CARUTHERSVILLE...UNION CITY  239 PM CDT SUN APR 24 2011    ...FLASH FLOOD WATCH NOW IN EFFECT THROUGH WEDNESDAY EVENING...    THE FLASH FLOOD WATCH IS NOW IN EFFECT FOR    * PORTIONS OF EAST ARKANSAS...SOUTHEAST MISSOURI AND WEST  TENNESSEE...INCLUDING THE FOLLOWING AREAS...IN EAST ARKANSAS...  CLAY...GREENE...LAWRENCE AND RANDOLPH. IN SOUTHEAST MISSOURI...  DUNKLIN AND PEMISCOT. IN WEST TENNESSEE...LAKE AND OBION.    * THROUGH WEDNESDAY EVENING.  * THIS IS A PARTICULARLY DANGEROUS SITUATION  * ADDITIONAL RAINFALL AMOUNTS OF 6 TO 9 INCHES ARE EXPECTED.  LOCALLY HIGHER AMOUNTS ARE LIKELY. THIS...IN COMBINATION OF  THE 2 TO 4 INCHES THAT HAVE ALREADY FALLEN MAY LEAD TO TOTAL  RAINFALL AMOUNTS IN EXCESS OF 12 INCHES IN MANY LOCATIONS.    * RAINFALL AMOUNTS SUCH AS THESE WILL LIKELY LEAD TO WIDESPREAD...  SIGNIFICANT...AND LIFE THREATENING FLASH FLOODING. THIS EVENT  MAY BE AS SEVERE AS THE MAY 1-2 2010 FLOODING IN MANY PLACES.  FLASH FLOODING OF CITIES...RURAL AREAS...RIVERS...AND SMALL  STREAMS ARE POSSIBLE.    PRECAUTIONARY/PREPAREDNESS ACTIONS...    A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD  TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.    YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION  SHOULD FLASH FLOOD WARNINGS BE ISSUED.    &&    $$    BORGHOFF

PDS flash flood warning

PDS flash flood warnings are issued when there is a higher than normal risk of widespread, life-threatening flash flooding. Like PDS flash flood watches, they are issued by the local NWS Weather Forecast Offices, rather than the Storm Prediction Center. Recently, they have been issued as PDS flash flood emergencies, most notably by the National Weather Service offices in Houston and Corpus Christi, Texas.

This warning was issued on September 27, 2024, by the National Weather Service Forecast Office in Greenville–Spartanburg, South Carolina, in response to devastating flooding in western North Carolina caused by Hurricane Helene.

PDS flash flood warning

 Flash Flood Warning

NCC023-027-111-291800- /O.NEW.KGSP.FF.W.0113.240927T2323Z-240929T1800Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED Flash Flood Warning National Weather Service Greenville-Spartanburg SC 723 PM EDT Fri Sep 27 2024

...FLASH FLOOD EMERGENCY FOR CATAWBA RIVER FROM LAKE JAMES TO LAKE RHODHISS...

The National Weather Service in Greenville-Spartanburg has issued a

• Flash Flood Warning for...

 Central Burke County in western North Carolina...  Southeastern Caldwell County in western North Carolina...  East Central McDowell County in western North Carolina...

• Until 200 PM EDT Sunday.

• At 723 PM EDT, Devastating rainfall of 6-25 (twenty-five) inches

 occurred from Wednesday evening through Friday morning from Lake  Hickory to the Catawba River headwaters, with the highest totals  exceeding 2 feet along the Blue Ridge Escarpment across the upper  Catawba River watershed.  This is resulting in catastrophic and  historic inflows into Lake James, and releases from Lake James are  causing catastrophic flooding along the Catawba River into Lake  Rhodhiss.

• The latest pool elevations for the upper Catawba River lakes are

 as follows (Full Pool is 100.0 feet):

   Lake James: 110.3 feet and rising steadily. RECORD BROKEN.    Lake Rhodhiss: 108.1 feet and rising steadily.

• The former record pool elevation at Lake James is 107.36 feet

 which occurred in September 8, 2004 during Hurricane Frances.  Major Flood Stage is 110.0 feet.

• The current record pool elevation at Lake Rhodhiss is 110.10 feet

 which occurred in August 1940.  Major Flood Stage is 110.0 feet.

• This is an unprecedented and extremely dangerous event. Residents

 are urged to heed guidance from emergency management and law  enforcement on any potential impacts to property.  We are pleading  with drivers to heed any barricades and avoid all flooded areas.  There have been numerous swift water rescues because people are  choosing to risk their lives and the lives of others by failing to  Turn Around Don`t Drown.  Please do the right thing and protect  your life, the life of your family, and the lives of those who  risk theirs to save you.

 This is a FLASH FLOOD EMERGENCY for Catawba River from Lake James  to Lake Rhodhiss. This is a PARTICULARLY DANGEROUS SITUATION. SEEK  HIGHER GROUND NOW!

 HAZARD...Life-threatening flash flooding from historic rainfall           and resultant dam floodgate releases.

 SOURCE...Duke Energy and Burke County Emergency Management.

 IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK           HIGHER GROUND NOW! Life-threatening flash-flooding of           Lake James, the Catawba River, and Lake Rhodhiss is           ongoing.  Structural flooding along Lake James           continues and is developing along Lake Rhodhiss.           Downstream of Bridgewater Dam on the Catawba River,           several structrues are damaged or destroyed, with some           single-level homes submerged by floodwaters.  These           floodwaters are causing numerous swift-water rescues.           Backwater effects are causing significant inundation           along tributaries, including flooding exceeding 4 ft           deep at the NC 18/US 64 bridge, blocking a primary           roadway connecting Morganton and Lenoir.

• Please stay weather aware and monitor lake levels and Duke Energy

 projections closely for any changes.

• For more information on lake levels or dam releases, people are

 encouraged to visit https://lakes.duke-energy.com or call  1-800-829-5253.

• Residents along the Catawba River are encouraged to stay aware of

 the latest updates from Burke County by signing up for alerts at:  http://smart911.com 

• McDowell County Emergency Management, Burke County Emergency

 Management, Caldwell County Emergency Management, and Duke Energy  are closely monitoring these high flows and pool levels and  additional updates will be provided as new information becomes  available.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to higher ground now! This is an extremely dangerous and life-threatening situation. Do not attempt to travel unless you are fleeing an area subject to flooding or under an evacuation order.

If you are in low-lying areas along the Catawba River you should move to higher ground immediately.

&&

LAT...LON 3583 8188 3577 8179 3584 8164 3581 8159

     3581 8146 3578 8135 3573 8139 3574 8143      3574 8159 3571 8176 3572 8194 3568 8202      3572 8206 3580 8191

FLASH FLOOD...OBSERVED FLASH FLOOD DAMAGE THREAT...CATASTROPHIC

$$

JMP

PDS high wind warning

PDS high wind warnings are issued by the National Weather Service when non-convective winds are expected to be especially damaging or dangerous to people and property, beyond what would be expected of a typical high wind warning.

The warning below was issued by the National Weather Service in Salt Lake City, Utah, on September 8, 2020, for an extreme downslope wind event in Salt Lake City and the northern Wasatch Front. ^[6]

PDS high wind warning

URGENT - WEATHER MESSAGE National Weather Service Salt Lake City UT 911 AM MDT Tue Sep 8 2020  UTZ002-003-082315- /O.CON.KSLC.HW.W.0006.000000T0000Z-200909T1500Z/ Northern Wasatch Front-Salt Lake and Tooele Valleys- Including the cities of Ogden, Bountiful, and Salt Lake City 911 AM MDT Tue Sep 8 2020  ...HIGH WIND WARNING REMAINS IN EFFECT UNTIL 9 AM MDT WEDNESDAY...  ...THIS IS A PARTICULARLY DANGEROUS SITUATION....  * WHAT...East winds 30 to 45 mph with gusts in excess of 70 mph   are expected. Wind gusts as high as 98 mph near Farmington,   Centerville and the mouth of Weber Canyon have been reported   this morning. This is a particularly dangerous situation.  * WHERE...Salt Lake and Tooele Valleys and Northern Wasatch   Front.  * WHEN...Until 9 AM MDT Wednesday.  * IMPACTS...High winds may move loose debris, damage property   and cause power outages. Travel will be difficult especially   for high profile vehicles. The most impacted travel routes are   expected to be along the I-15 corridor between Salt Lake City   and Layton, the Legacy Parkway, the US 89 corridor in Davis   and Weber Counties, and Foothill Drive.  * ADDITIONAL DETAILS...Stay inside! Flying debris and numerous   falling trees may be deadly.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  People are urged to secure loose objects that could be blown around or damaged by the wind.  &&  $$

PDS red flag warning

PDS red flag warnings are issued by the National Weather Service to inform the public that there is an unusually high threat of wildland fire combustion, and rapid spread of wildfires, due to very dry fuels, very low humidity levels, and strong winds.

The PDS red flag warning below was issued by the National Weather Service in Reno, Nevada, on December 19, 2017. ^[7]

On August 3, 2018, the National Weather Service in Reno, Nevada, issued another PDS red flag warning to communicate the threat of life-threatening fire danger due to strong gusty winds and low humidity.

On April 12, 2022, the National Weather Service in Norman, Oklahoma, issued a PDS red flag warning because of an extreme fire weather behavior (overlap of extremely dry fuels, humidity as low as 8 percent and wind gusting to 60 mph). ^[8]

PDS red flag warning

 URGENT - FIRE WEATHER MESSAGE  National Weather Service Reno NV  140 PM PST Tue Dec 19 2017    CAZ273-201500-  /O.CON.KREV.FW.W.0017.171220T0300Z-171221T0300Z/  Mono and Eastern Alpine Counties-  140 PM PST Tue Dec 19 2017    ...RED FLAG WARNING REMAINS IN EFFECT FROM 7 PM THIS EVENING TO  7 PM PST WEDNESDAY FOR GUSTY WINDS AND LOW HUMIDITY FOR MONO  COUNTY SOUTH OF MONO LAKE...    ...THIS IS A PARTICULARLY DANGEROUS SITUATION...    AFFECTED AREA...Fire Zone 273 Mono and Eastern Alpine Counties.    Winds...Southwest 25 to 40 mph with gusts up to 70 mph late  tonight into Wednesday morning. The winds will shift to the  north by early Wednesday afternoon with speeds of 20 to 30 mph  and gusts to 55 mph.    Location and timing of strongest wind gusts...The strongest  wind gusts will be along the 395 corridor tonight into  Wednesday morning. Wednesday afternoon the strongest gusts  will be in the Owens and Chalfant Valleys.    Humidity...As low as 10 to 20% tonight and again late  Wednesday afternoon. Brief recovery near or above 50% is  possible late Wednesday morning.    Duration...10 to 15 hours, locally up to 20 hours.    Impacts...The combination of gusty winds and low humidity can  cause fire to rapidly grow in size and intensity.    PRECAUTIONARY/PREPAREDNESS ACTIONS...    This is a particularly dangerous situation with low humidity and  very high winds. New fires will grow rapidly out of control, in  some cases people may not be able to evacuate safely in time  should a fire approach. Avoid outdoor activities that can cause a  spark near dry vegetation, such as yard work, target shooting, or  campfires. Follow local fire restrictions. Check weather.gov/reno  for updates and livingwithfire.info for preparedness tips.

PDS severe thunderstorm watch

PDS severe thunderstorm watches are issued when there is a higher than normal risk of severe thunderstorm winds capable of major structural damage (in addition to large hail and perhaps a few isolated tornadoes), usually due to a strong and persistent derecho. These watches are very rare (accounting an average of only two each year), as the risk for tornadoes must remain low enough to not warrant a tornado watch (a normal tornado watch would be issued if the tornado risk is significant alongside the extreme wind threat). ^[3]

This PDS severe thunderstorm watch shown below was issued by the Storm Prediction Center in Norman, Oklahoma, on May 12, 2022, for a derecho in portions of Iowa, Minnesota, Nebraska, and South Dakota. ^[9]

PDS severe thunderstorm watch

  SEL8

  URGENT - IMMEDIATE BROADCAST REQUESTED   Severe Thunderstorm Watch Number 208   NWS Storm Prediction Center Norman OK   325 PM CDT Thu May 12, 2022

  The NWS Storm Prediction Center has issued a

  * Severe Thunderstorm Watch for portions of      Northwest Iowa     Southwest Minnesota     Northeast Nebraska     Southeast South Dakota

  * Effective this Thursday afternoon and evening from 325 PM until     1000 PM CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

  * Primary threats include...     Widespread damaging winds and scattered significant gusts to 105       mph expected     Scattered large hail likely with isolated very large hail events       to 2 inches in diameter possible     A couple tornadoes possible

  SUMMARY...A prolific wind-damage event is expected unfold from   northeast Nebraska into southeast South Dakota and northwest   Iowa/southwest Minnesota. Pockets of significant wind damage are   highly likely, along with the potential for large hail and possible   a line-embedded tornado or two.

  The severe thunderstorm watch area is approximately along and 60   statute miles north and south of a line from 60 miles west of   Mitchell SD to 5 miles east northeast of Spencer IA. For a complete   depiction of the watch see the associated watch outline update   (WOUS64 KWNS WOU8).

  PRECAUTIONARY/PREPAREDNESS ACTIONS...

  REMEMBER...A Severe Thunderstorm Watch means conditions are   favorable for severe thunderstorms in and close to the watch area.   Persons in these areas should be on the lookout for threatening   weather conditions and listen for later statements and possible   warnings. Severe thunderstorms can and occasionally do produce   tornadoes.

  &&

  OTHER WATCH INFORMATION...CONTINUE...WW 205...WW 206...WW 207...

  AVIATION...A few severe thunderstorms with hail surface and aloft to   2 inches. Extreme turbulence and surface wind gusts to 90 knots. A   few cumulonimbi with maximum tops to 550. Mean storm motion vector   22045.

  ...Guyer

PDS special marine warning

PDS Special marine warnings are issued by the National Weather Service to inform mariners of weather conditions that present a considerable threat to life and property.

On April 19, 2018, the Baltimore/Washington, D.C. forecast office upgraded a special marine warning to PDS status as a gust front approached Chesapeake Bay. ^[10]

PDS special marine warning

National Weather Service Baltimore MD/Washington DC  1138 AM EDT THU APR 19 2018    ANZ537-191700-   /O.CON.KLWX.MA.W.0020.000000T0000Z-180419T1700Z/  1138 AM EDT THU APR 19 2018    ...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 100 PM EDT...    For the following areas...  Tidal Potomac from Cobb Island MD to Smith Point VA...    At 1137 AM EDT, a gust front was located near Quantico Marine Base,  moving southeast at 25 knots. Numerous wind gusts of 35 to 45 knots  have been observed with this line.    HAZARD...Wind gusts 34 knots or greater.    SOURCE...Radar indicated.    IMPACT...Boaters in small craft could be thrown overboard by  suddenly higher winds and waves capsizing their vessel.    Locations impacted include...  Yeocomico River...  Breton Bay...  Point Lookout...  Coltons Point...  Saint Clements Bay...  Coles Point...  Mouth Of The Potomac River...  Saint George Island...  White Point Beach...  Tall Timbers...  and Piney Point.    PRECAUTIONARY/PREPAREDNESS ACTIONS...    This is a particularly dangerous situation. Sudden onset of gale  force winds can cause even experienced mariners to capsize.  Capsizing in cold water is especially dangerous and can quickly  result in hypothermia. If you haven't already done so, move to safe  harbor now!    &&    LAT...LON 3797 7641 3801 7647 3802 7651 3807 7654  3811 7660 3815 7661 3817 7676 3817 7685  3826 7686 3825 7684 3823 7660 3821 7657  3814 7652 3806 7633 3801 7629 3791 7627  TIME...MOT...LOC 1537Z 310DEG 27KT 3871 7777 3813 7848      HAIL...0.00in  WIND...>34kts    $$    DHOF

PDS special weather statement

PDS special weather statements are usually issued by the NWS for hazards that do not have a specific code of their own, and pose an exceptionally high risk of damage and loss of life.

The PDS special weather statement below was issued by the National Weather Service in Buffalo, New York, on December 11, 2013, regarding extreme amounts of lake effect snow to impact the defined area.^{[ citation needed ]} The same office issued multiple PDS Special Weather Statements for hurricane-force winds forecast to hit the Buffalo area on February 24, 2019. ^{[11] [12] [13]}

PDS special weather statement

 SPECIAL WEATHER STATEMENT  NATIONAL WEATHER SERVICE BUFFALO NY  255 PM EST WED DEC 11 2013    NYZ006>008-112200-  OSWEGO-JEFFERSON-LEWIS-  INCLUDING THE CITIES OF...OSWEGO...WATERTOWN...LOWVILLE  255 PM EST WED DEC 11 2013    ...EXTREMELY HEAVY LAKE EFFECT SNOW TO CONTINUE THROUGH THE  EVENING COMMUTE...    A BAND OF VERY INTENSE LAKE EFFECT SNOW EXTENDING FROM BETWEEN  SANDY CREEK AND ADAMS ALONG I-81...EASTWARD TO LOWVILLE AND  CROGHAN WILL CONTINUE THROUGH THE AFTERNOON. OTHER AREAS IMPACTED  BY THIS SNOW BAND INCLUDE BUT ARE NOT LIMITED TO  MONTAGUE...MARTINSBURG...HIGHMARKET...TURIN...SANDY  CREEK...LACONA...PULASKI...LOWVILLE AND LYONS FALLS. THIS BAND  WILL DRIFT SLIGHTLY NORTH OVER THE NEXT COUPLE OF HOURS. SNOWFALL  RATES OF 3 TO 5 INCHES PER HOUR CAN BE EXPECTED WITHIN THE MOST  INTENSE LAKE BANDS. IN ADDITION...WEST WINDS BETWEEN 15 TO 30 MPH  WILL RESULT IN CONSIDERABLE BLOWING AND DRIFTING SNOW...REDUCING  VISIBILITIES TO NEAR ZERO AT TIMES MAKING FOR WHITE OUT  CONDITIONS.    ...THIS IS A PARTICULARLY DANGEROUS SITUATION...    THIS WILL PRODUCE TREACHEROUS TRAVEL CONDITIONS ACROSS THE TUG   HILL...INTERSTATE 81 FROM PULASKI TO ADAMS...AND ALONG STATE   ROUTE 12 FROM TURIN TO LOWVILLE. TRAVEL ACROSS THESE AREAS WILL  BE NEARLY IMPOSSIBLE THIS AFTERNOON...AND IS HIGHLY DISCOURAGED.    $$    JAM

PDS tornado watch

PDS tornado watches are issued when there is a significantly higher than normal risk of multiple EF2 or stronger tornadoes – especially those that are predicted to be long-track in nature, with path lengths of more than 20 miles – in the watch area (usually amounting to damage consistent with EF4 or EF5 tornadoes at maximum), in addition to including significant wind and hail damage. This enhanced wording in a Tornado Watch is meant to alert the public of the potential for very life-threatening severe weather. Under current criteria, such would be issued when the probability for significant tornadoes is 80% or greater. PDS Tornado Watches are often issued on high risk days for severe weather, though have been issued on high-end moderate risk days. ^[14]

The PDS tornado watch shown below was issued on April 27 during the tornado outbreak sequence of April 25–28, 2024. ^[15]

PDS tornado watch

 URGENT - IMMEDIATE BROADCAST REQUESTED   Tornado Watch Number 146   NWS Storm Prediction Center Norman OK   1240 PM CDT Sat Apr 27 2024     The NWS Storm Prediction Center has issued a     * Tornado Watch for portions of      Western Oklahoma     Northwest Texas     * Effective this Saturday afternoon and evening from 1240 PM     until 800 PM CDT.     ...THIS IS A PARTICULARLY DANGEROUS SITUATION...    * Primary threats include...     Several tornadoes and a few intense tornadoes likely     Widespread large hail and scattered very large hail events to 3       inches in diameter likely     Widespread damaging winds and isolated significant gusts to 75       mph likely    SUMMARY...Intense thunderstorms are expected to develop this   afternoon along and east of a dryline over western Oklahoma and   northwest Texas.  Supercells are expected, capable of very large   hail and damaging winds.  The most intense cells may also produce   strong or potentially long-tracked tornadoes.    The tornado watch area is approximately along and 70 statute miles   east and west of a line from 35 miles east northeast of Alva OK to   45 miles southwest of Wichita Falls TX. For a complete depiction of   the watch see the associated watch outline update (WOUS64 KWNS   WOU6).    PRECAUTIONARY/PREPAREDNESS ACTIONS...    REMEMBER...A Tornado Watch means conditions are favorable for   tornadoes and severe thunderstorms in and close to the watch   area. Persons in these areas should be on the lookout for   threatening weather conditions and listen for later statements   and possible warnings.    &&    OTHER WATCH INFORMATION...CONTINUE...WW 144...WW 145...    AVIATION...Tornadoes and a few severe thunderstorms with hail   surface and aloft to 3 inches. Extreme turbulence and surface wind   gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean   storm motion vector 24035.    ...Hart

PDS tornado warning

PDS tornado warnings are currently issued on an experimental basis by the 38 National Weather Service Weather Forecast Offices within the Central Region. ^[16] The criteria for a PDS warning are when a tornado on the ground has been spotted or confirmed, or a significant tornado is expected based on radar signatures. While the intention of this experimental warning may be to replace the loosely defined tornado emergency, PDS tornado warnings are structured as the second highest level of tornado warning within the impact based warning system (an experiment – which also includes tags within warning products illustrating radar indications or physical observations of tornadoes, and damage potential – participated by the 33 Weather Forecast Offices within the Central Region, as well as eight additional offices within the Western, Eastern and Southern regions that began utilizing the system in the spring of 2014 ^[17] ); a tornado emergency, the highest warning level, is used within the United States for destructive tornadoes approaching more densely populated areas. These are the first warnings issued with PDS wording, and like PDS flash flood watches, are issued by local forecast offices. ^{[18] [19]}

Below is an example of a PDS Tornado Warning, issued for the 2021 Naperville–Woodridge tornado on June 20, 2021.

PDS tornado warning

083  WWUS53 KLOT 210416 SVSLOT  Severe Weather Statement National Weather Service Chicago/Romeoville 1116 PM CDT Sun Jun 20 2021  ILC031-043-197-210445- /O.CON.KLOT.TO.W.0004.000000T0000Z-210621T0445Z/ Will IL-DuPage IL-Cook IL- 1116 PM CDT Sun Jun 20 2021  ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1145 PM CDT FOR NORTHWESTERN WILL...SOUTHEASTERN DUPAGE AND SOUTH CENTRAL COOK COUNTIES...          At 1115 PM CDT, a confirmed large and extremely dangerous tornado  was located over Darien, or over far east Woodridge, moving east at  45 mph. Radar confirms debris with this tornado moving over  populated areas.  This is a PARTICULARLY DANGEROUS SITUATION. TAKE COVER NOW!  HAZARD...Damaging tornado.  SOURCE...Radar confirmed tornado.  IMPACT...You are in a life-threatening situation. Flying debris may           be deadly to those caught without shelter. Mobile homes           will be destroyed. Considerable damage to homes,           businesses, and vehicles is likely and complete destruction           is possible.  The tornado will be near...   Burr Ridge, Western Springs and Indian Head Park around 1120 PM    CDT.   Palos Hills, Justice, Summit, Bridgeview, Hickory Hills,    Countryside, Willow Springs and Hodgkins around 1125 PM CDT.   Oak Lawn, Midway Airport, Burbank, Alsip, Chicago Ridge, Palos    Heights, Crestwood and Worth around 1130 PM CDT.  Other locations in the path of this tornadic thunderstorm include Chicago Lawn, Oak Forest, Ashburn, Evergreen Park and Midlothian.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  To repeat, a large, extremely dangerous and potentially deadly tornado is on the ground. To protect your life, TAKE COVER NOW! Move to a basement or an interior room on the lowest floor of a sturdy building. Avoid windows. If you are outdoors, in a mobile home, or in a vehicle, move to the closest substantial shelter and protect yourself from flying debris.  &&  LAT...LON 4166 8817 4178 8811 4180 8769 4151 8778 TIME...MOT...LOC 0415Z 275DEG 41KT 4175 8799   TORNADO...OBSERVED TORNADO DAMAGE THREAT...CONSIDERABLE HAIL...<.75IN  OEMC zones...TORNADO WARNING. 8 and 10.   $$  FRIEDLEIN 

^[20]

PDS wind chill warning

PDS wind chill warnings are issued when there is an enhanced risk of frost bite, hypothermia, and eventually death due to extremely low wind chills. These warnings are issued by the National Weather Service Weather Forecast Offices rather than the Storm Prediction Center.

The PDS wind chill warning shown below was issued by the National Weather Service in the Twin Cities on January 5, 2014. ^[21]

PDS wind chill warning

629  WWUS43 KMPX 050957  WSWMPX    URGENT - WINTER WEATHER MESSAGE  NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN  357 AM CST SUN JAN 5 2014    ...HISTORIC AND LIFE-THREATENING COLD AIR HAS ARRIVED...  ...THIS IS A PARTICULARLY DANGEROUS SITUATION...    THE COLDEST AIRMASS SINCE 1996 CONTINUES TO MOVE SOUTHEAST OUT  OF CANADA AND INTO MINNESOTA AND WISCONSIN. WIND CHILL VALUES WILL  RANGE BETWEEN 30 AND 45 BELOW TODAY AND CONTINUE TO FALL THROUGH  MONDAY MORNING. AIR TEMPERATURES TONIGHT WILL DROP INTO THE 20S  AND 30S BELOW ZERO. GUSTY WEST OR NORTHWEST WINDS COMBINED WITH  THESE EXTREMELY COLD TEMPERATURES WILL PRODUCE WIND CHILLS OF 50  TO 65 BELOW ZERO LATE TONIGHT AND EARLY MONDAY.    WIND CHILLS COLDER THAN 50 BELOW CAN CAUSE EXPOSED FLESH TO  FREEZE IN ONLY 5 MINUTES. A WIND CHILL WARNING IS IN EFFECT FOR  CENTRAL AND SOUTHERN MINNESOTA AND WEST CENTRAL WISCONSIN THROUGH  NOON TUESDAY.    THE GUSTY WINDS WILL ALSO BRING AREAS OF BLOWING SNOW TO MUCH OF  THE AREA TODAY AND TONIGHT. WHERE GUSTS REACH 35 TO 45 MPH OVER  WESTERN AND SOUTHERN MINNESOTA...VISIBILITIES MAY OCCASIONALLY BE  REDUCED TO LESS THAN A HALF MILE IN NEAR BLIZZARD CONDITIONS. THIS  WILL BRING AN ADDITIONAL LEVEL OF DANGER TO ANYONE STRANDED.    MNZ041-047-048-054>057-064-065-067-073>075-082>085-091>093-052115-  /O.CON.KMPX.WC.W.0001.000000T0000Z-140107T1800Z/  DOUGLAS-STEVENS-POPE-LAC QUI PARLE-SWIFT-CHIPPEWA-KANDIYOHI-  YELLOW MEDICINE-RENVILLE-SIBLEY-REDWOOD-BROWN-NICOLLET-WATONWAN-  BLUE EARTH-WASECA-STEELE-MARTIN-FARIBAULT-FREEBORN-  INCLUDING THE CITIES OF...ALEXANDRIA...MORRIS...GLENWOOD...  MADISON...BENSON...MONTEVIDEO...WILLMAR...GRANITE FALLS...  OLIVIA...GAYLORD...REDWOOD FALLS...NEW ULM...ST. PETER...  ST. JAMES...MANKATO...WASECA...OWATONNA...FAIRMONT...BLUE EARTH...  ALBERT LEA  357 AM CST SUN JAN 5 2014    ...WIND CHILL WARNING REMAINS IN EFFECT UNTIL NOON CST TUESDAY...    A WIND CHILL WARNING REMAINS IN EFFECT UNTIL NOON CST TUESDAY.    * THIS IS A PARTICULARLY DANGEROUS SITUATION!  * WIND CHILL VALUES: 35 TO 65 BELOW...WITH THE COLDEST READINGS  TONIGHT AND MONDAY MORNING.    * IMPACTS: EXPOSED FLESH WILL FREEZE IN 10 MINUTES WITH WIND  CHILLS OF 35 BELOW...AND IN 5 MINUTES WITH WIND CHILLS OF 50  BELOW OR COLDER.    * OTHER IMPACTS...WINDS GUSTING BETWEEN 35 AND 45 MPH THIS  AFTERNOON AND TONIGHT WILL LEAD TO BLOWING SNOW WITH  VISIBILITIES OCCASIONALLY DROPPING TO 1/2 MILE OR LESS IN NEAR  BLIZZARD CONDITIONS. SHOULD YOUR VEHICLE BECOME STRANDED...YOUR  LIFE WILL BE AT RISK. CONSIDER POSTPONING ALL TRAVEL.    PRECAUTIONARY/PREPAREDNESS ACTIONS...    A WIND CHILL WARNING MEANS THE COMBINATION OF VERY COLD AIR AND  STRONG WINDS WILL CREATE DANGEROUSLY LOW WIND CHILL VALUES. THIS  WILL RESULT IN FROST BITE AND LEAD TO HYPOTHERMIA OR DEATH IF  PRECAUTIONS ARE NOT TAKEN.    &&    $$    MNZ042>045-049>053-058>063-066-068>070-076>078-WIZ014>016-023>028-  052115  /O.CON.KMPX.WC.W.0001.000000T0000Z-140107T1800Z/  TODD-MORRISON-MILLE LACS-KANABEC-STEARNS-BENTON-SHERBURNE-ISANTI-  CHISAGO-MEEKER-WRIGHT-HENNEPIN-ANOKA-RAMSEY-WASHINGTON-MCLEOD-  CARVER-SCOTT-DAKOTA-LE SUEUR-RICE-GOODHUE-POLK-BARRON  RUSK-  ST. CROIX-PIERCE-DUNN-PEPIN-CHIPPEWA-EAU CLAIRE-  INCLUDING THE CITIES OF...LONG PRAIRIE...LITTLE FALLS...  PRINCETON...MORA...ST. CLOUD...FOLEY...ELK RIVER...CAMBRIDGE...  CENTER CITY...LITCHFIELD...MONTICELLO...MINNEAPOLIS...BLAINE...  ST. PAUL...STILLWATER...HUTCHINSON...CHASKA...SHAKOPEE...  BURNSVILLE...LE SUEUR...FARIBAULT...RED WING...AMERY...  BALSAM LAKE...RICE LAKE...BARRON...LADYSMITH...HUDSON...  NEW RICHMOND...RIVER FALLS...PRESCOTT...MENOMONIE...BOYCEVILLE...  DURAND...PEPIN...CHIPPEWA FALLS...BLOOMER...EAU CLAIRE...ALTOONA    357 AM CST SUN JAN 5 2014    ...WIND CHILL WARNING REMAINS IN EFFECT UNTIL NOON CST TUESDAY...    A WIND CHILL WARNING REMAINS IN EFFECT UNTIL NOON CST TUESDAY.    * THIS IS A PARTICULARLY DANGEROUS SITUATION!  * WIND CHILL VALUES: 35 TO 65 BELOW...WITH THE COLDEST READINGS  TONIGHT AND MONDAY MORNING.    * IMPACTS: EXPOSED FLESH WILL FREEZE IN 10 MINUTES WITH WIND  CHILLS OF 35 BELOW...AND IN 5 MINUTES WITH WIND CHILLS OF 50  BELOW OR COLDER.    * OTHER IMPACTS...AREAS OF BLOWING SNOW ARE POSSIBLE AS WINDS GUST  AS HIGH AS 35 MPH THIS AFTERNOON AND TONIGHT.    PRECAUTIONARY/PREPAREDNESS ACTIONS...    A WIND CHILL WARNING MEANS THE COMBINATION OF VERY COLD AIR AND  STRONG WINDS WILL CREATE DANGEROUSLY LOW WIND CHILL VALUES. THIS  WILL RESULT IN FROST BITE AND LEAD TO HYPOTHERMIA OR DEATH IF  PRECAUTIONS ARE NOT TAKEN.    &&    $$    BORGHOFF

Other watches and warnings

While the use of PDS wording for other types of watches and warnings has not been used, PDS wording could theoretically be applied to any kind of watch or warning to alert the public to weather events where there exists an increased risk of loss of life or widespread damage to property. Such situations could include PDS watches or warnings for blizzards, ice storms, or extreme heat. For example, on October 29, 2012, in advance of Hurricane Sandy, which was expected to become post-tropical prior to making landfall, a high wind warning was issued for New Jersey stating "This is an extremely dangerous situation!" ^[22] Similarly, on May 26, 2015, during the flood disaster in Texas, Oklahoma, Arkansas, and Louisiana, a flood warning was issued similar to a PDS flood warning stating "...This is a dangerous and life-threatening situation..." ^[23] A severe thunderstorm warning bulletin issued by the National Weather Service at Tampa Bay/Ruskin regarding a strong, tornadic storm system moving through the area contained the following: "This storm may cause serious injury and significant property damage." ^[24] Several severe thunderstorm warnings issued by the National Weather Service in Goodland, Kansas on June 8, 2024, contained the phrasing "this is an extremely dangerous situation" prompted by "tornado like wind speeds" in the range of 80–100 mph (130–160 km/h). ^{[25] [26] [27]}

References

1. NOAA (2004-04-18). "Storm Prediction Center Frequently Asked Questions (FAQ)" . Retrieved 2008-05-23.
2. "National Weather Service Issues Area Red Flag Warning" . Retrieved 2018-08-04.
3. Dean, Andrew R. (2006-11-07). "PDS watches: how dangerous are these "particularly dangerous situations?" (2006 - 23SLS_23sls)". American Meteorological Society. Retrieved 2008-05-23.
4. Lewis, John (2007-11-03). "A Forecaster's Story: Robert H. Johns". Electronic Journal of Severe Storms Meteorology. 2 (7). doi: 10.55599/ejssm.v2i7.12 .
5. "IEM Valid Time Extent Code (VTEC) App". Mesonet.agron.iastate.edu. Retrieved 2014-01-22.
6. National Weather Service (2020-09-08). "Iowa Environmental Mesonet NWS Product Archive" . Retrieved 2020-09-08.
7. National Weather Service (2017-12-19). "Iowa Environmental Mesonet NWS Product Archive" . Retrieved 2018-04-18.
8. "IEM :: Valid Time Event Code (VTEC) App".
9. NOAA (2022-05-12). "Storm Prediction Center: Particularly Dangerous Situation (PDS) Severe Thunderstorm Watch 208".
10. Herzmann, Daryl. "IEM :: Valid Time Event Code (VTEC) App". mesonet.agron.iastate.edu. Retrieved 2018-04-19.
11. herzmann, daryl. "IEM :: SPS from NWS BUF". mesonet.agron.iastate.edu. Retrieved 2023-01-18.
12. herzmann, daryl. "IEM :: SPS from NWS BUF". mesonet.agron.iastate.edu. Retrieved 2023-01-18.
13. herzmann, daryl. "IEM :: SPS from NWS BUF". mesonet.agron.iastate.edu. Retrieved 2023-01-18.
14. Brugge, R. (December 1994). "The Alabama tornado outbreak of 27 March 1994 - an example of tornado formation". Weather. 49 (12): 407–411. Bibcode:1994Wthr...49..407B. doi:10.1002/j.1477-8696.1994.tb05961.x. ISSN   0043-1656.
15. "Storm Prediction Center PDS Tornado Watch 146". Storm Prediction Center. Storm Prediction Center. Retrieved 31 March 2023.
16. "Impact Based Warning Experimental Product". Crh.noaa.gov. Retrieved 2014-01-22.
17. National Weather Service (2014). "Impact Based Warnings". National Oceanic and Atmospheric Administration . Retrieved March 12, 2014.
18. "Enhanced Product – Tornado Warnings and Associated Follow-up Statements Modified to Emphasize Impacts, Intensity, and Recommended Actions via Bulleted Messages and Coded Tag Lines" (PDF). NWS. Archived from the original (PDF) on 13 April 2012. Retrieved 15 April 2012.
19. "'CATASTROPHIC': Experimental Tornado Warnings to be Explicit". AccuWeather . 2012-04-05. Archived from the original on 2014-03-13. Retrieved 2014-03-12.
20. "Tornado Warning". Iowa State University Iowa Environmental Mesonet. National Weather Service Forecast Office in Romeoville, Illinois. Retrieved 24 April 2024.
21. National Weather Service (2014-01-05). "Iowa Environmental Mesonet NWS Product Archive" . Retrieved 2014-01-06.
22. "High Wind Warning – Hurricane Sandy". National Weather Service – Philadelphia/Mount Holly. Retrieved 29 October 2017.
23. Payne, Ed; Shoichet, Catherine (26 May 2015). "Running updates: Storms slam Houston, kill 31 in Texas, Oklahoma, Mexico". CNN. Retrieved 30 October 2017.
24. "Tampa Bay/Ruskin – Severe Thunderstorm Warning". National Weather Service. Retrieved 30 October 2017.
25. "IEM :: Valid Time Event Code (VTEC) App". Iowa Environmental Mesonet. National Weather Service Forevast Office in Goodland, Kansas. Retrieved March 25, 2020.
26. "IEM :: Valid Time Event Code (VTEC) App". Iowa Environmental Mesonet. National Weather Service Forevast Office in Goodland, Kansas. Retrieved March 25, 2020.
27. "IEM :: Valid Time Event Code (VTEC) App". Iowa Environmental Mesonet. National Weather Service Forevast Office in Goodland, Kansas. Retrieved March 25, 2020.

 This article incorporates public domain material from websites or documents of the National Oceanic and Atmospheric Administration .

External links

• NOAA-NWS Storm Prediction Center