SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
432 AM EDT MON MAY 23 2011
VALID 12Z MON MAY 23 2011 - 12Z WED MAY 25 2011
...THREAT FOR HEAVY RAIN CONTINUES ACROSS THE MIDDLE MISSISSIPPI
VALLEY...
...SEVERE THUNDERSTORMS ARE POSSIBLE FROM THE SOUTHERN PLAINS TO
THE NORTHERN MID-ATLANTIC STATES...
A MAJORITY OF THE COUNTRY WILL CONTINUE TO EXPERIENCE UNSETTLED
WEATHER OVER THE NEXT FEW DAYS. IN THE EAST...AN AREA OF LOW
PRESSURE WILL QUICKLY MOVE NORTHEASTWARD INTO EASTERN
CANADA...BRINGING WIDESPREAD SHOWERS TO MUCH OF THE GREAT LAKES
REGION AND INTERIOR NORTHEAST MONDAY AFTERNOON AND INTO TUESDAY
MORNING. THE NORTHERN PORTION OF A TRAILING FRONT WILL SLOWLY
PUSH EASTWARD INTO THE NORTHEAST MONDAY NIGHT AND
TUESDAY...RESULTING IN CONTINUED SHOWERS AND A FEW THUNDERSTORMS
DURING THE DAY TUESDAY. A FEW OF THESE STORMS COULD BE STRONG.
TO THE SOUTH...WARM...MOIST GULF AIR WILL ENCOUNTER THE SOUTHERN
PORTION OF THE TRAILING FRONT...CREATING A RISK FOR SEVERE
THUNDERSTORMS FROM THE SOUTHERN PLAINS TO THE OHIO RIVER VALLEY ON
MONDAY. THESE STORMS MAY BE ACCOMPANIED BY HEAVY DOWNPOURS...HIGH
WINDS...HAIL...AND TORNADOES. THIS PORTION OF THE FRONT WILL
REMAIN QUASI-STATIONARY OVER THE SOUTHERN PLAINS...MIDDLE
MISSISSIPPI VALLEY...AND OHIO VALLEY...MEANING MANY OF THE SAME
PLACES MAY HAVE TO DEAL WITH ANOTHER ROUND OF SEVERE WEATHER ON
TUESDAY. ELSEWHERE...INSTABILITY CAUSED BY DAYTIME HEATING WILL
TRIGGER A FEW SCATTERED SHOWERS AND THUNDERSTORMS FROM THE
SOUTHERN APPALACHIANS INTO THE MID-ATLANTIC ON MONDAY.
MEANWHILE...A CLOSED UPPER-LOW WILL CONTINUE TO SPIN OVER THE
NORTHWEST AS THE FORECAST PERIOD BEGINS. THE ENERGY WILL TRIGGER
SHOWERS AND THUNDERSTORMS ACROSS THE NORTHERN AND CENTRAL ROCKIES
ON MONDAY AND TUESDAY. ENERGY FROM THIS LOW WILL MAKE ITS WAY
ACROSS THE ROCKIES AND INTO THE PLAINS BY WEDNESDAY MORNING. THIS
WILL AIDE IN DEVELOPING A STRONG SURFACE CYCLONE OVER THE CENTRAL
PLAINS ON WEDNESDAY AND BRINING MORE UNSETTLED WEATHER TO THE
REGION IN FORM OF HEAVY RAIN AND SEVERE THUNDERSTORMS.
UPSTREAM...ANOTHER STRONG DISTURBANCE WILL APPROACH THE PACIFIC
NORTHWEST. PRECIPITATION COULD BEGIN TO MOVE INTO THE COASTAL
REGIONS OF OREGON AND WASHINGTON OVERNIGHT TUESDAY AND INTO THE
EARLY MORNING HOURS ON WEDNESDAY.
GERHARDT
AY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0809 PM CDT SUN MAY 22 2011
VALID 230100Z - 231200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS FAR WEST CENTRAL
ILLINOIS...PORTIONS OF CENTRAL AND SOUTHERN MISSOURI...NORTHEAST
OKLAHOMA...AND NORTHWEST ARKANSAS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE GREAT LAKES/OH
VALLEY/CENTRAL APPALACHIANS REGION SWWD INTO THE SRN PLAINS...
...UPPER GREAT LAKES REGION SWWD TO SWRN TX...
AN EXTENSIVE/BROKEN BAND OF THUNDERSTORMS -- INCLUDING
LARGE/EMBEDDED SUPERCELLS -- EXTENDS FROM UPPER MI/WI SWWD INTO THE
TRANSPECOS REGION OF TX AND ADJACENT NRN MEXICO. NRN PORTIONS OF
THE BAND ARE ASSOCIATED WITH THE SURFACE COLD FRONT...WITH THE MORE
SRN PORTIONS OF THE BAND INTO OK/TX MORE TIED TO A DRYLINE.
WIDESPREAD STORMS HAVE OVERTURNED THE AIRMASS IN MANY
LOCALES...EFFECTIVELY REDUCING WHAT WAS STRONG INSTABILITY --
PARTICULARLY ACROSS MANY AREAS FROM NRN IL NWD. HOWEVER...STRONG
INSTABILITY /MIXED-LAYER CAPE RANGING FROM 2000 TO 4000 J/KG/
REMAINS FROM CENTRAL MO SWWD TO SWRN TX...AND ANOTHER RESERVOIR OF
MIXED-LAYER CAPE UP TO 2000 J/KG REMAINS ACROSS LOWER MI.
GIVEN FAVORABLE SHEAR FOR SUPERCELLS ACROSS THE MAJORITY OF THIS
AREA...WILL MAINTAIN SLIGHT RISK FROM LOWER MI SWWD TO SWRN TX...AND
WILL MAINTAIN MODERATE RISK FROM THE STL /ST. LOUIS MO/ VICINITY
SWWD INT NWRN AR/NERN OK. DAMAGING WINDS AND LARGE HAIL WILL REMAIN
THE PRIMARY SEVERE THREATS...THOUGH ISOLATED TORNADOES REMAIN
POSSIBLE THIS EVENING -- PARTICULARLY ACROSS THE MODERATE RISK AREA.
...OH AND TN VALLEYS INTO THE CENTRAL APPALACHIANS...
TWO CLUSTERS OF STRONG/LOCALLY SEVERE STORMS CONTINUE ATTM -- ONE
ACROSS NERN INDIANA/NWRN OH/SRN LOWER MI AND THE OTHER CROSSING THE
CENTRAL APPALACHIANS REGION IN CONJUNCTION WITH AN UPPER SHORT-WAVE
TROUGH. WHILE THESE STORMS SHOULD WEAKEN SLOWLY WITH TIME...WILL
MAINTAIN SLIGHT RISK ACROSS THIS AREA FOR MARGINAL HAIL/DAMAGING
WIND POTENTIAL. FINALLY...ALL HIGH-RES MODELS HINT THAT STORMS NOW
ONGOING ACROSS MO MAY EVOLVE INTO AN MCS AND SHIFT ACROSS MO/NRN AR
AND THE MID MS VALLEY INTO THE OH AND TN VALLEYS OVERNIGHT. WHILE
LESS UNSTABLE AIR IS EVIDENT ACROSS MUCH OF KY AND TN IN THE WAKE OF
EARLIER STORMS NOW IN THE CENTRAL APPALACHIANS...HAIL AND ISOLATED
DAMAGING WINDS WILL BE POSSIBLE -- MAINLY FROM SRN INDIANA/WRN
KY/WRN TN WWD.
..GOSS.. 05/23/2011
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM CDT MON MAY 23 2011
VALID 241200Z - 251200Z
...THERE IS A MDT RISK OF SVR TSTMS LATE TUE AFTN INTO TUE NIGHT
ACROSS CENTRAL AND EASTERN OKLAHOMA...MUCH OF CENTRAL AND EASTERN
KANSAS...PARTS OF SOUTHWEST MISSOURI...NORTHWEST ARKANSAS AND NORTH
CENTRAL TEXAS...
...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
AREA ACROSS MUCH OF THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI
VALLEY...EASTWARD THROUGH PARTS OF THE LOWER OHIO AND TENNESSEE
VALLEYS...AND NORTHEASTWARD THROUGH THE NORTHERN MID ATLANTIC COAST
STATES AND HUDSON VALLEY...
...AN OUTBREAK OF SEVERE THUNDERSTORMS AND TORNADOES IS POSSIBLE
LATE TUESDAY AFTERNOON AND EVENING...
...SYNOPSIS...
MODELS INDICATE THAT THE LARGE-SCALE TROUGH...NOW DEVELOPING INTO
THE WESTERN U.S...GRADUALLY SPLITS...WITH A SIGNIFICANT SOUTHERN
PORTION SLOWLY LIFTING EAST NORTHEASTWARD OUT OF THE SOUTHERN
PLATEAU BY EARLY TUESDAY...AS ANOTHER LARGE AND STRONG IMPULSE
APPROACHES THE PACIFIC COAST. THE LEAD TROUGH...WITH AT LEAST A
COUPLE OF SIGNIFICANT EMBEDDED SMALLER SCALE IMPULSES...IS PROGGED
TO EVOLVE INTO A CLOSED LOW AS IT MIGRATES ACROSS THE SOUTHERN
ROCKIES INTO THE CENTRAL PLAINS LATER TUESDAY AND TUESDAY NIGHT.
ASSOCIATED FORCING FOR UPWARD VERTICAL MOTION APPEARS LIKELY TO
CONTRIBUTE TO FURTHER DEEPENING OF A SURFACE CYCLONE OVER THE SOUTH
CENTRAL PLAINS. THIS IS EXPECTED TO BE ACCOMPANIED BY A
STRENGTHENING SOUTHERLY LOW-LEVEL JET IN EXCESS OF 50 KT AT 850 MB
BY EARLY TUESDAY EVENING...FROM NORTH CENTRAL TEXAS INTO EASTERN
KANSAS...AS A CYCLONIC AND GENERALLY WESTERLY 70 KT 500 MB JET
STREAK NOSES INTO AND THROUGH THE SOUTHERN PLAINS RED RIVER VALLEY
REGION.
AT THE SAME TIME...A LARGE COLD UPPER VORTEX WITH SEVERAL STRONG
EMBEDDED SHORT WAVE IMPULSES WILL LINGER OVER MUCH OF EASTERN
CANADA. AN ASSOCIATED SIGNIFICANT COLD FRONT APPEARS LIKELY TO
ADVANCE SOUTHEAST OF THE GREAT LAKES THROUGH MUCH OF THE
NORTHEAST...AS ANOTHER IMPULSE...PERHAPS CONVECTIVELY
ENHANCED...WITHIN THE SOUTHERN BRANCH OF THE SPLIT UPPER
FLOW...LIFTS OUT OF THE OHIO VALLEY THROUGH SOUTHERN NEW ENGLAND BY
12Z WEDNESDAY.
GIVEN THE CONTINUING PRESENCE OF A SEASONABLY MOIST BOUNDARY LAYER
AIR MASS IN THE WARM SECTOR OF THE PLAINS CYCLONE...AND ALONG AND
AHEAD OF THE EASTERN COLD FRONT...DESTABILIZATION PROBABLY WILL
BECOME SUFFICIENT TO SUPPORT CONSIDERABLE STRONG/SEVERE STORM
DEVELOPMENT DURING THIS PERIOD. ASIDE FROM SOME SEA BREEZE STORMS
IN THE SOUTHEAST...THIS WILL MOSTLY REMAIN WEST AND NORTH OF
PERSISTENT SUBTROPICAL RIDGING CENTERED JUST EAST OF THE SOUTH
ATLANTIC COAST.
...CENTRAL/SOUTHERN PLAINS...
LINGERING VARIABILITY AMONG THE MODELS AND ENSEMBLES CONCERNING THE
TIMING AND TRACK OF THE TROUGH EMERGING FROM THE SOUTHWEST CONTINUES
TO COMPLICATE THE FORECAST. BUT IT APPEARS THAT THIS WILL ONLY
IMPACT THE EXACT PLACEMENT OF THE HIGHEST SEVERE PROBABILITIES...AS
THE EVOLVING LARGE-SCALE PATTERN SEEMS SUPPORTIVE OF A FAIRLY
CLASSIC SEVERE WEATHER OUTBREAK. AND ENOUGH COMMON GROUND APPEARS
TO EXIST TO JUSTIFY AN UPGRADE TO MODERATE RISK SEVERE PROBABILITIES
ACROSS MUCH OF CENTRAL/EASTERN KANSAS AND OKLAHOMA...PORTIONS OF
NORTH CENTRAL TEXAS...NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI.
SURFACE DEW POINTS AROUND 70F ARE PROGGED IN THE WARM SECTOR OF THE
DEEPENING CYCLONE...ALONG AND EAST OF A SHARPENING DRY LINE DURING
THE LATE AFTERNOON HOURS...WHEN PEAK AFTERNOON HEATING AND
STEEPENING LAPSE RATES ASSOCIATED WITH MID-LEVEL COOLING PROBABLY
WILL CONTRIBUTE TO MIXED LAYER CAPE OF 2000-4000 J/KG. AS THE
MID-LEVEL JET NOSES INTO THE RED RIVER VALLEY...THE DRY LINE IS
EXPECTED TO BECOME THE FOCUS FOR THE PRIMARY STORM DEVELOPMENT AS IT
SURGES NORTHEASTWARD OUT OF SOUTH CENTRAL KANSAS...AND EASTWARD OUT
OF CENTRAL OKLAHOMA...THROUGH MUCH OF EASTERN KANSAS AND OKLAHOMA BY
LATE EVENING. GIVEN THE ANTICIPATED WIND PROFILES...EXHIBITING
STRONG DEEP LAYER SHEAR AND LARGE CLOCKWISE CURVED LOW-LEVEL
HODOGRAPHS...THE ENVIRONMENT IS EXPECTED TO BECOME CONDUCIVE TO
LONG-LIVED SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL AND
STRONG TORNADOES. THIS THREAT MAY CONTINUE THROUGH MUCH OF THE
EVENING...PERHAPS INTO THE 06-09Z TIME FRAME...GRADUALLY SPREADING
TOWARD THE LOWER MISSOURI VALLEY AND OZARKS...BEFORE DIMINISHING IN
THE PRESENCE OF A MORE STABLE OR STABILIZING BOUNDARY LAYER.
...NORTHERN MID ATLANTIC STATES INTO THE LOWER HUDSON VALLEY...
WEAK TO MODERATE DESTABILIZATION ALONG AND AHEAD OF THE
SOUTHEASTWARD ADVANCING COLD FRONT...AND WITHIN THE PRE-FRONTAL LEE
SURFACE TROUGH...IS EXPECTED TO PROVIDE THE FOCUS FOR VIGOROUS
CONVECTIVE DEVELOPMENT WITH THE APPROACHING UPPER IMPULSE TUESDAY
AFTERNOON. MODELS ARE A BIT MORE UNCLEAR CONCERNING THE STRENGTH OF
THE VERTICAL SHEAR...BUT IT SHOULD BE ENOUGH TO SUPPORT POTENTIAL
FOR ORGANIZED STORM CLUSTERS...AND ISOLATED SUPERCELLS MAY NOT BE
OUT OF THE QUESTION. THIS COULD IMPACT MUCH OF THE URBAN
CORRIDOR...FROM WASHINGTON D.C./BALTIMORE TO NEW YORK CITY...BEFORE
CONVECTION DIMINISHING/SPREADS OFFSHORE WITH UPPER FORCING BY
TUESDAY EVENING.
..KERR.. 05/23/2011
I can't believe it happened again, my best wishes are with the people that have been affected.
