Monday, October 17, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 171609
SWODY1
SPC AC 171607

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1107 AM CDT MON OCT 17 2011

VALID 171630Z - 181200Z

...NO SVR TSTM AREAS FORECAST...

...SOUTHERN PLAINS...
MORNING WATER VAPOR IMAGERY SHOWS A WELL-DEFINED SHORTWAVE TROUGH
DIGGING ACROSS THE FOUR-CORNERS REGION. THIS FEATURE WILL SWEEP
INTO THE CENTRAL/SOUTHERN PLAINS THIS EVENING. AFTER 00Z...MODELS
AGREE ON RAPIDLY INTENSIFYING NORTHERLY LOW LEVEL WINDS BEHIND A
COLD FRONT THAT WILL SURGE SOUTHWARD ACROSS THE SOUTHERN HIGH
PLAINS. LOW LEVEL WINDS AHEAD OF THE FRONT WILL NOT RESPOND/
INCREASE SIGNIFICANTLY TONIGHT...BUT INCREASING CONVERGENCE ALONG
THE FRONT WILL LEAD TO A LINE OF SHOWERS AND THUNDERSTORMS FROM
CENTRAL MO INTO NORTH TX.

MOISTURE IS SPREADING SLOWLY NORTHWARD ACROSS TX...WITH 50S
DEWPOINTS NOW INTO SOUTHEAST OK. A COMBINATION OF STRONG DAYTIME
HEATING AND COOLING TEMPERATURES ALOFT WILL YIELD AFTERNOON MLCAPE
UP TO 1000 J/KG NEAR THE APPROACHING FRONT. HOWEVER...FORECAST
SOUNDINGS SUGGEST THAT AN EML WILL LIKELY CAP THE WARM SECTOR AND
PRECLUDE DEEP CONVECTION. THE STORMS THAT FORM ARE EXPECTED TO BE
ALONG/BEHIND THE FRONT WHERE LIFT WILL BE SUFFICIENTLY DEEP. STEEP
MID LEVEL LAPSE RATES...COOLING TEMPERATURES ALOFT...AND STRENGTH OF
FORCING SUGGEST A RISK OF HAIL NEAR SEVERE LIMITS WITH THESE STORMS.
ALSO...STRONG NORTHERLY LOW LEVEL WINDS WILL NEED ONLY SLIGHT
CONVECTIVE AUGMENTATION TO PRODUCE LOCALLY DAMAGING GUSTS. THE
THREAT SHOULD DIMINISH BY MIDNIGHT AS DIURNAL COOLING WEAKENS
INSTABILITY. A SMALL SLIGHT RISK WAS CONSIDERED NEAR THE RED RIVER
/SOUTH OK AND NORTH TX/ WHERE INSTABILITY AND WIND FIELDS WOULD BE
MAXIMIZED...BUT TOO MUCH UNCERTAINTY REMAINS AT THIS TIME.

...FL KEYS...
LOCAL RADAR LOOPS CONTINUE TO SHOW SEVERAL SMALL SUPERCELLULAR
STORMS OFF THE SOUTHWEST COAST OF THE FL PENINSULA INCLUDING NEAR
THE KEYS. THIS SCENARIO WILL LIKELY PERSIST THROUGH THE AFTERNOON
IN NORTHEAST QUADRANT OF WEAK TROPICAL LOW. LIGHTNING DATA SHOWS
VERY FEW STRIKES IN THIS ACTIVITY...SUGGESTING THAT UPDRAFTS ARE NOT
PARTICULARLY STRONG. NEVERTHELESS...AN ISOLATED WATERSPOUT OR
TORNADO CANNOT BE RULED OUT.

..HART/ROGERS.. 10/17/2011

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