Varsler, Outlooks etc.

Når der er fare for severe weather (uvejr), sættes en nøje fastlagt varslingsprocedure igang. Den involverer både Storm Prediction Center og National Weather Service.

De har hver deres ansvarsområder.  Varslingerne udsendes til både traditionelle medier og sociale medier (Facebook, Twitter).

Nedenfor følger i kronologisk rækkefølge "varslingskæden" :

 

Convective Outlooks (udstedes af Storm Prediction Center - SPC)

Storm Prediction Center (SPC) udsender 3 dage frem udsigter for severe weather (uvejr) - de såkaldte "Outlook"s. Udsigterne benævnes Day…

Storm Prediction Center (SPC) udsender 3 dage frem udsigter for severe weather (uvejr) - de såkaldte "Outlook"s.

Udsigterne benævnes Day 1, Day 2 og Day 3.day1-20110427-1630

Udsigterne markeres som områder på et USA kort og kategoriseres efter nedenstående mønster :

  • MRGL (Marginal - et område med meget lille risiko for spredt uvejr)
  • SLGT (Slight Risk - dvs. lille risiko for uvejr med enkelte tornadoer)
  • ENH (Enhanced - dvs. forøget risiko for uvejr med enkelte tornadoer)
  • MDT (Moderate Risk - dvs. moderat risiko for udbredt uvejr med adskillige tornadoer)
  • HIGH (High Risk - dvs. stor risiko for et større udbrud af uvejr med mange tornadoer)


I tornadosæsonen (medio marts - ultimo maj) er der stort set Slight Risk et eller andet sted i USA hver dag. Kun ifm med udbredt højtryksvejr, kan der være dage hvor kortet er tomt. Moderate Risk varsles flere gange om måneden, mens High Risk kun ses en eller 2 gange på en normal sæson.

Udover de kategoriserede kort, udsendes også et kort hvor de procentvise sandsynligheder for specifikke hændelser angives, dvs for store hagl, tornadoer og vindstød.

Da disse outlooks er for "severe weather" - altså uvejr med fare for menneskeliv, kan der godt opstå "almindeligt" tordenvejr selvom der er ikke er et af ovenstående outlooks ude.

 

Posted 9 years ago

Emergency (sjældent brugt - udstedes af den lokale vejrtjeneste - NWS)

I sjældne tilfælde, når en visuelt bekræftet, voldsom tornado nærmer sig tæt beboede områder og der er overhængende fare for…

I sjældne tilfælde, når en visuelt bekræftet, voldsom tornado nærmer sig tæt beboede områder og der er overhængende fare for tab af mange menneskeliv, kan vejrtjenesten udsende en såkaldt Tornado Emergency. Det er den højeste varslingsklasse.

Et eksempel på en Tornado Emergency :

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DODGE CITY KS
941 PM CDT FRI MAY 4 2007

...A TORNADO EMERGENCY FOR GREENSBURG....

AT 937 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS AND STORM
SPOTTERS WERE TRACKING A LARGE AND EXTREMELY DANGEROUS TORNADO. THIS
TORNADO WAS LOCATED 5 MILES SOUTH OF GREENSBURG...MOVING NORTH AT 20
MPH.

A VIOLENT TORNADO WAS ON A DIRECT PATH FOR PORTIONS OF GREENSBURG...
ESPECIALLY THE EASTERN PORTIONS OF TOWN. TAKE IMMEDIATE TORNADO
PRECATIONS...THIS IS AN EMERGENCY SITUATION FOR GREENSBURG!!

A TORNADO WATCH REMAINS IN EFFECT UNTIL 200 AM CDT SATURDAY MORNING
FOR SOUTHWESTERN KANSAS


 

Posted 9 years ago

Hvor tit ser man en tornado ?

I modsætning til hvad mange Hollywood produktioner og diverse serier forsøger at overbevise os om, er en tornado et relativt…

I modsætning til hvad mange Hollywood produktioner og diverse serier forsøger at overbevise os om, er en tornado et relativt sjældent fænomen.

Der findes mange amerikanere der har boet hele deres liv i Tornado Alley, der aldrig har set en tornado. Flere stormchasere har chaset i flere år uden at have oplevet en tornado.

Vi har været heldige at have oplevet mindst en tornado de år vi har chaset, med undtagelse at et enkelt år.

At opleve en tornado kræver både dygtighed, erfaring, intuition og ikke mindst held.

2 superceller der umiddelbart opstår under de samme meteorologiske betingelser, vil måske ende med at den ene producerer en tornado, mens den anden ikke gør. Hvorfor ?

Dette er ikke 100% forstået endnu, og det er det mange forskningsprojekter forsøger at afdække. Det er her heldet og intuitionen spiller ind.

Posted 9 years ago

Mesoscale Discussion - MCD (udstedes af Storm Prediction Center - SPC)

En Mesoscale (Convective) Discussion (MCD) er skridtet efter et "Outlook" i varslingsrækkefølgen. MCD udsendes af Storm Prediction Center (SPC), når…

En Mesoscale (Convective) Discussion (MCD) er skridtet efter et "Outlook" i varslingsrækkefølgen.

MCD udsendes af Storm Prediction Center (SPC), når betingelserne for uvejr er ved at være til stede.

En MCD efterfølges ofte kort tid efter af et "Watch"

En MCD indeholder en beskrivelse af de meteorologiske forhold, og er primært møntet på de lokale meteorologiske afdelinger.

Et exempel på en MCD :

  MESOSCALE DISCUSSION 0685
   NWS STORM PREDICTION CENTER NORMAN OK
   0253 PM CDT FRI MAY 04 2007
   
   AREAS AFFECTED...WRN KS...PARTS OF WRN OK/ERN TX PNHDL
   
   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 
   
   VALID 041953Z - 042200Z
   
   TRENDS ARE BEING CLOSELY MONITORED FOR SIGNS OF CONVECTIVE
   INITIATION.  ALTHOUGH TIMING IS STILL A BIT UNCERTAIN...ONE OR MORE
   TORNADO WATCHES WILL PROBABLY BE REQUIRED LATE THIS AFTERNOON.
   
   MOISTENING SOUTHERLY LOW-LEVEL FLOW AND STRONG DAYTIME HEATING ALONG
   SOUTHERN HIGH PLAINS DRY LINE...INTO THE VICINITY OF WEAK SURFACE
   LOW OVER SOUTHWEST KANSAS...IS CONTRIBUTING TO STRONG
   DESTABILIZATION.  RUC GUIDANCE INDICATES MIXED LAYER CAPE IS
   INCREASING INTO THE 3000-4000 J/KG RANGE...THOUGH MID-LEVEL
   SUBSIDENCE/SHORT WAVE RIDGING ALOFT IS CURRENTLY INHIBITING
   CONVECTIVE DEVELOPMENT.
   
   HOWEVER...MID/UPPER FORCING ASSOCIATED WITH AN IMPULSE LIFTING OUT
   OF AMPLIFIED WESTERN TROUGH IS BEGINNING TO SHIFT EAST OF THE
   CENTRAL/SOUTHERN ROCKIES.  AND...LATEST RUC GUIDANCE SUGGESTS WEAK
   LOWER/MID TROPOSPHERIC COOLING HAS OCCURRED ACROSS WESTERN KANSAS
   INTO THE TEXAS PANHANDLE ASSOCIATED WITH IMPULSE ALREADY LIFTING
   NORTHWARD THROUGH THE NORTH CENTRAL HIGH PLAINS.  ALTHOUGH
   UNCERTAINTY DOES EXISTS CONCERNING TIMING OF CONVECTIVE
   INITIATION...MUCH OF MODEL GUIDANCE SUGGESTS THAT THIS COULD OCCUR
   AS EARLY AS 22-23Z.  THIS SEEMS MOST PROBABLE WHERE FORCING WILL BE
   STRONGEST NEAR SURFACE LOW...BUT INITIATION OF WIDELY SCATTERED
   STORMS MAY QUICKLY FOLLOW SUITE.
   
   STORM DEVELOPMENT/INTENSIFICATION WILL LIKELY BE VERY RAPID ONCE CAP
   BREAKS.  AND...LARGE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS BENEATH
   40-50 KT CYCLONIC WEST SOUTHWESTERLY 500 MB FLOW WILL BE FAVORABLE
   FOR TORNADOES...IN ADDITION TO THE RISK OF VERY LARGE HAIL. 
   ISOLATED STRONG TORNADOES ARE POSSIBLE...PARTICULARLY AS LOW-LEVEL
   JET STRENGTHENS NEAR/SHORTLY AFTER 04/00-01Z.
   
   ..KERR.. 05/04/2007
   
   
   ATTN...WFO...ICT...OUN...GID...DDC...GLD...LUB...AMA...
   
   38660150 39630029 39799943 38919814 37039815 35499848
   34599966 34380083 35150103 35890059 36590025 36920043
   37260135  
Posted 9 years ago

Particular Dangerous Situation - PDS (udstedes af Storm Prediction Center - SPC)

Er der en dag stor risiko, sandsynlighed og forventning for et udbrud af kraftige tornadoer eller en kraftig derecho, kan…

Er der en dag stor risiko, sandsynlighed og forventning for et udbrud af kraftige tornadoer eller en kraftig derecho, kan SPC i forbindelse med udsendelse af et watch bruge ordlyden

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

Så kaldes det pågældende watch for en PDS - Particular Dangerous Situation.

Et eksempel på en PDS :

URGENT - IMMEDIATE BROADCAST REQUESTED
   TORNADO WATCH NUMBER 232
   NWS STORM PREDICTION CENTER NORMAN OK
   955 AM CDT SAT MAY 5 2007
   
   THE NWS STORM PREDICTION CENTER HAS ISSUED A
   TORNADO WATCH FOR PORTIONS OF 
   
          PARTS OF WESTERN AND CENTRAL KANSAS
          PARTS OF SOUTHWEST AND CENTRAL NEBRASKA
   
   EFFECTIVE THIS SATURDAY MORNING AND EVENING FROM 955 AM UNTIL
   1000 PM CDT.
   
   ...THIS IS A PARTICULARLY DANGEROUS SITUATION...
   
   DESTRUCTIVE TORNADOES...LARGE HAIL TO 4 INCHES IN DIAMETER...
   THUNDERSTORM WIND GUSTS TO 90 MPH...AND DANGEROUS LIGHTNING ARE
   POSSIBLE IN THESE AREAS.
   
   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 100 STATUTE
   MILES EAST AND WEST OF A LINE FROM 45 MILES NORTH NORTHWEST OF
   BROKEN BOW NEBRASKA TO 55 MILES SOUTHWEST OF RUSSELL KANSAS.  FOR
   A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
   OUTLINE UPDATE (WOUS64 KWNS WOU2).
   
   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.
   
   DISCUSSION...VERY POTENT TORNADIC SUPERCELL PATTERN IN PLACE ACROSS
   WATCH AREA AS AIR MASS IS EXTREMELY UNSTABLE WITH VERY FAVORABLE
   SHEAR PROFILES.  WITH LITTLE INHIBITION REMAINING ALONG E OF DRY
   LINE...STORMS WILL RAPIDLY BECOME SEVERE BY EARLY THIS AFTERNOON WRN
   KS INTO SWRN NEB.  TORNADIC SUPERCELLS WILL DEVELOP WITH POTENTIAL
   FOR LONG TRACK/VIOLENT TORNADOS.  AS DRY LINE REMAINS WRN KS THRU
   THE AFTERNOON...ADDITIONAL DEVELOPMENT OF TORNADIC SUPERCELLS ARE
   LIKELY  OFF THE DRY LINE THRU THE EVENING HOURS.
   
   AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
   SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE
   WIND GUSTS TO 80 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
   600. MEAN STORM MOTION VECTOR 22040.
   
   
   ...HALES
Posted 9 years ago

Warnings (udstedes af den lokale vejrtjeneste - NWS)

De lokale filialer af National Weather Service (NWS) har ansvaret for at varsle befolkningen i deres ansvarsområde, hvis en vejrsituation…

De lokale filialer af National Weather Service (NWS) har ansvaret for at varsle befolkningen i deres ansvarsområde, hvis en vejrsituation udvikler sig farligt efter fastlagte kriterier.

Der udsendes så en "warning" - dvs. en advarsel om at en bestemt farlig vejrtype er indtruffet eller umiddelbart forestående.

Der skelnes mellem

  • Severe Thunderstorm Warning
  • Tornado Warning
  • Flash Flood Warning

En Severe Thunderstorm Warning udsendes, når en tordenbyge producerer hagl over 3/4 tomme og/eller 50 knob

Et exempel på en warning :

SEVERE THUNDERSTORM WARNING
 OHC035-153-080300-
 /O.NEW.KCLE.SV.W.0206.070808T0200Z-070808T0300Z/

 BULLETIN - EAS ACTIVATION REQUESTED
 SEVERE THUNDERSTORM WARNING
 NATIONAL WEATHER SERVICE CLEVELAND OH
 1000 PM EDT TUE AUG 7 2007

 THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A

 * SEVERE THUNDERSTORM WARNING FOR...
 CUYAHOGA COUNTY IN NORTHEAST OHIO
 SUMMIT COUNTY IN NORTHEAST OHIO

 * UNTIL 1100 PM EDT

 * AT 950 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR NORTH ROYALTON...OR ABOUT 11 MILES NORTH OF MEDINA...AND MOVING EAST AT 40 MPH. * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO MACEDONIA...TWINSBURG AND SOLON THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER... PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS. LAT...LON 4146 8139 4127 8139 4126 8138 4126 8140 4126 8151 4125 8167 4128 8168 4128 8179 4137 8182 $$ FITZ

En Tornado Warning udsendes, når en tornado er visuelt observeret eller en TVS (Tornadic Vortex Signature) er detekteret på radar.

Et exempel på en warning :

TORNADO WARNING
 OHC103-092115-
 /O.NEW.KCLE.TO.W.0022.070809T2023Z-070809T2115Z/

 BULLETIN - EAS ACTIVATION REQUESTED
 TORNADO WARNING
 NATIONAL WEATHER SERVICE CLEVELAND OH
 423 PM EDT THU AUG 9 2007

 THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A

 * TORNADO WARNING FOR...
 MEDINA COUNTY IN NORTHEAST OHIO...

 * UNTIL 515 PM EDT

 * AT 419 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
 SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 7 MILES WEST OF
 LODI...OR ABOUT 15 MILES WEST OF MEDINA...MOVING EAST AT 40 MPH.

 * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
 WADSWORTH

 IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER IN A NEARBY REINFORCED
 BUILDING. AS A LAST RESORT...SEEK SHELTER IN A CULVERT...DITCH OR LOW
 SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

 THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A
 WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS
 AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN
 INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO
 COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS.

 IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
 SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE
 NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

 LAT...LON 4100 8217 4114 8216 4114 8207 4117 8206
 4116 8169 4099 8168

 $$

 LAPLANTE

En Flash Flood Warning udsendes, når meget kraftig nedbør ifm med en tordenbyge er konstatetet. Specielt HP superceller udløser ofte Flash Flood Warnings. Lokal topografi kan også være en medbestemmende faktor til hvornår en warning udsendes.

Et exempel på en warning :

FLASH FLOOD WARNING
 KSC003-302230-

 BULLETIN - EAS ACTIVATION REQUESTED
 FLASH FLOOD WARNING
 NATIONAL WEATHER SERVICE TOPEKA KS
 1129 AM CDT SAT JUN 30 2007

 THE NATIONAL WEATHER SERVICE IN TOPEKA HAS ISSUED A

 * FLASH FLOOD WARNING FOR...
 ANDERSON COUNTY IN EAST CENTRAL KANSAS...

 * UNTIL 530 PM CDT SATURDAY

 * AT 1129 AM CDT...THE PUBLIC REPORTED WATER FLOWING OVER A COUPLE
 OF PAVED ROADS NEAR WESTPHALIA. ANDERSON COUNTY EMERGENCY
 MANAGEMENT ALSO INDICATED THAT SEVERAL PAVED ROADS HAD WATER RISING
 AND APPROACHING ROADWAYS. DOPPLER RADAR INDICATED THAT ANOTHER BAND
 OF HEAVY RAINFALL WAS DEVELOPING AND TRAINING OVER ANDERSON COUNTY
 PRODUCING RAINFALL RATES UP TO ONE INCH PER HOUR. ENHANCED RAINFALL
 RATES WILL LIKELY BE ENOUGH TO BRING WATER OVER SEVERAL PAVED ROADS
 IN THE COUNTY

 * LOCATIONS IMPACTED INCLUDE...
 HARRIS...
 GREELEY...
 GARNETT...
 WESTPHALIA...

 RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS AND
 STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY ROADS AND FARMLANDS
 ALONG THE BANKS OF CREEKS AND STREAMS AND LOW LYING AREAS ARE SUBJECT
 TO FLASH FLOODING.

 A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
 IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
 RESIDENTS ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE PRECAUTIONS
 TO PROTECT LIFE AND PROPERTY.

 TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
 YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN
 TOPEKA.

 STAY TUNED TO NOAA WEATHER RADIO OR LOCAL MEDIA OUTLETS FOR THE
 LATEST INFORMATION CONCERNING THE SEVERE WEATHER.

 LAT...LON 3803 9551 3803 9507 3839 9506 3838 9550

 $$


Posted 9 years ago

Watches (udstedes af Storm Prediction Center - SPC)

Er der udsigt til farligt vejr inden for kort tid, kan Storm Prediction Center (SPC) udsende et forvarsel - et…

Er der udsigt til farligt vejr inden for kort tid, kan Storm Prediction Center (SPC) udsende et forvarsel - et "watch".

Man inddeler watchs i 3 klasser :

  • Severe Thunderstorm
  • WatchTornado Watch
  • Flash Flood Watch


Et Severe Thunderstorm Watch udsendes når der inden for kort tid er risiko for at en tordenbyge kan producere hagl over 3/4 tomme (2 cm) og vindstød på over 50 knob.

Et eksempel på et Severe Thunderstorn Watch :

URGENT - IMMEDIATE BROADCAST REQUESTED
 SEVERE THUNDERSTORM WATCH NUMBER 589
 NWS STORM PREDICTION CENTER NORMAN OK
 400 PM CDT SUN AUG 12 2007

 THE NWS STORM PREDICTION CENTER HAS ISSUED A
 SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

 SOUTHWEST IOWA
 EXTREME NORTHWEST AND NORTH CENTRAL MISSOURI

 EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 400 PM UNTIL
 1100 PM CDT.

 HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80
 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

 THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY LONG AND 55
 STATUTE MILES NORTH AND SOUTH OF A LINE FROM 20 MILES OUTH OF
 OMAHA NEBRASKA TO 35 MILES NORTH OF KIRKSVILLE MISSOURI.

 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
 UPDATE (WOUS64 KWNS WOU9).

 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 588...

 DISCUSSION...BOW ECHO MCS APPEARS TO BE ORGANIZING W OF OMAHA...AND
 THIS CONVECTIVE COMPLEX WILL LIKELY PROGRESS ESEWD ALONG A
 BAROCLINIC ZONE NEAR THE MO/IA BORDER. MLCAPE VALUES OF 4000-5000
 J/KG AND MODEST DEEP LAYER SHEAR ALONG THE BOUNDARY WILL HELP
 MAINTAIN STORM INTENSITY INTO THE EVENING. RELATIVELY WIDESPREAD
 DAMAGING WINDS WILL BE POSSIBLE ALONG THE PATH OF THIS
 SYSTEM...ALONG WITH LARGE HAIL.

 AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
 TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70
 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM
 MOTION VECTOR 29035.


 ...THOMPSON

Et Tornado Watch udsendes når der inden for kort tid er risiko for tornadoer og er samtidigt også et Severe Thundestorm Watch.

Et exempel på et Tornado Watch :

URGENT - IMMEDIATE BROADCAST REQUESTED
 TORNADO WATCH NUMBER 600
 NWS STORM PREDICTION CENTER NORMAN OK
 1030 PM EDT WED AUG 15 2007

 THE NWS STORM PREDICTION CENTER HAS ISSUED A
 TORNADO WATCH FOR PORTIONS OF

 NORTHERN INDIANA
 NORTHWEST OHIO
 LAKE MICHIGAN

 EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 1030 PM
 UNTIL 400 AM EDT.

 TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
 TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

 THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 40 STATUTE
 MILES NORTH AND SOUTH OF A LINE FROM 20 MILES SOUTH SOUTHWEST OF
 VALPARAISO INDIANA TO 65 MILES EAST OF FORT WAYNE INDIANA. FOR A
 COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
 UPDATE (WOUS64 KWNS WOU0).

 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.

 DISCUSSION...SMALL MCS OVER NW IND HAS FORMED IN THE PAST 90 MINUTES
 ON WRN SIDE OF COLD POOL/MCV ASSOCIATED WITH EARLIER CONVECTIVE
 SYSTEM. THE MCS SHOULD REMAIN STRONG THROUGH EARLY THURSDAY AND
 TRACK ESE INTO OH. A SUPERCELL NOW PRESENT ON WRN SIDE OF SYSTEM
 WILL POSE A THREAT FOR ISOLATED TORNADOES...IN ADDITION TO DAMAGING
 WET MICROBURSTS/ MARGINALLY SVR HAIL...GIVEN HI PWS AND LOW LEVEL
 WIND FIELD WITH CONSIDERABLE DEGREE OF SPEED/DIRECTIONAL SHEAR.
 WIND PROFILES MAY ALSO SUPPORT BACK-BUILDING DEVELOPMENT ON WRN SIDE
 OF MCS...WITH ASSOCIATED LOCALLY HEAVY RAIN POSSIBLE INTO FAR NE
 IL/NRN IND IN WAKE OF SUPERCELL.

 AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
 SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
 GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550.
 MEAN STORM MOTION VECTOR 30030.

 ...CORFIDI

Et Flash Flood Watch udsendes således når der inden for kort tid er risiko for kraftigt regnskyl med oversvømmelser til følge.

Et exempel på et Flash Flood Watch :

FLOOD WATCH
 NATIONAL WEATHER SERVICE SAN JUAN PR
 1037 AM AST SAT MAY 3 2008

 PRZ001>011-040245-
 /O.EXT.TJSJ.FF.A.0002.000000T0000Z-080504T0300Z/
 /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
 SAN JUAN AND VICINITY-NORTHEAST-SOUTHEAST-EASTERN INTERIOR-
 NORTH CENTRAL-CENTRAL INTERIOR-PONCE AND VICINITY-NORTHWEST-
 WESTERN INTERIOR-MAYAGUEZ AND VICINITY-SOUTHWEST-
 INCLUDING THE MUNICIPALITIES AND/OR ISLANDS OF...SAN JUAN...
 CAROLINA...FAJARDO...HUMACAO...GUAYAMA...ARROYO...YABUCOA...
 SALINAS...COCO...CAGUAS...ARECIBO...VEGA BAJA...DORADO...COAMO...
 COROZAL...AIBONITO...VILLALBA...JAYUYA...PONCE...AGUADILLA...
 ISABELA...HATILLO...QUEBRADILLAS...UTUADO...SABANA GRANDE...LARES...
 ADJUNTAS...HORMIGUEROS...MOCA...AGUADA...LUYANDO...CABO ROJO...LAJAS
 1037 AM AST SAT MAY 3 2008

 ...FLASH FLOOD WATCH NOW IN EFFECT THROUGH THIS EVENING...

 THE FLASH FLOOD WATCH IS NOW IN EFFECT FOR

 * ALL OF PUERTO RICO

 * THROUGH 11 PM THIS EVENING

 * THE RAPID APPROACH OF ANOTHER MID TO UPPER LEVEL SHORT WAVE
 TROUGH DIGGING SOUTHEAST TOWARDS THE REGION...AND THE PROXIMITY
 OF A SURFACE TROUGH SINKING SOUTH ACROSS THE DOMINICAN REPUBLIC
 AND THE MONA PASSAGE...COMBINED WITH ABUNDANT LOW LEVEL TROPICAL
 MOISTURE AND DIURNAL AND LOCAL ISLAND EFFECTS...WILL AGAIN RESULT
 IN THE DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS AND
 THUNDERSTORMS...SOME WITH VERY HEAVY RAINFALL ACROSS PUERTO RICO
 AT LEAST THROUGH THIS AFTERNOON. IN ADDITION...GROUNDS ACROSS THE
 WATCH AREA REMAIN AT OR NEAR SATURATION AND MANY RIVERS REMAIN AT
 ABOVE NORMAL LEVELS ESPECIALLY ALONG THE NORTHERN AND EAST
 SECTION OF THE ISLAND.

 * ADDITIONAL RAINFALL OF 1 TO 3 INCHES...WITH LOCALLY HIGHER
 AMOUNTS POSSIBLY OVER 5 INCHES ARE EXPECTED OVER PARTS OF PUERTO RICO
 THROUGH THIS AFTERNOON AS SHOWERS ACTIVITY MAY RAPIDLY BE
 ENHANCED WITH THE DAYTIME HEATING. THIS RAINFALL COULD RESULT IN
 ADDITIONAL FLASH AND RIVER FLOODING. ALSO...ROCK AND MUDSLIDES
 (DEBRIS FLOW) ARE POSSIBLE OVER AREAS OF STEEP TERRAIN.

 A FLASH FLOOD WATCH MEANS THAT CONDITIONS ARE FAVORABLE FOR HEAVY
 RAIN ACROSS THE WATCH AREA...WHICH MAY LEAD TO FLOODING. IF YOU ARE
 IN THE WATCH AREA...CHECK YOUR PREPAREDNESS REQUIREMENTS...ESPECIALLY
 IF YOU HAVE INTERESTS ALONG AREA RIVERS. KEEP INFORMED... AND BE
 READY FOR QUICK ACTION IF FLOODING IS OBSERVED OR IF A FLASH FLOOD
 WARNING IS ISSUED.

 PEOPLE IN THE WATCH AREA SHOULD CONTINUE TO BE AWARE OF THE
 POSSIBILITY FOR HEAVY RAINFALL. AVOID LOW LYING AREAS...AND BE
 CAREFUL WHEN APPROACHING HIGHWAY DIPS AND UNDERPASSES. ADDITIONAL
 HEAVY RAIN MAY CONTINUE TO CAUSE MUDSLIDES IN AREAS OF STEEP
 TERRAIN.

 STAY TUNED TO NOAA WEATHER RADIO...LOCAL TV...RADIO OR YOUR CABLE
 TELEVISION PROVIDER FOR LATER STATEMENTS AND POSSIBLE WARNINGS.

 THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGICAL AND CLIMATE
 INFORMATION...IS AVAILABLE ON THE WEB AT HTTP://WWW.SRH.NOAA.GOV/SJU
 OR AT HTTP://WEATHER.GOV.

 $$
Posted 9 years ago

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