SWODY1
SPC AC 191959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SUN JUL 19 2009
VALID 192000Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SERN OK/NRN AND ERN
TX/SWRN AR AND NWRN LA...
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE HIGH PLAINS...
...SRN PLAINS...
A SLIGHT RISK HAS BEEN ADDED TO PORTIONS OF ERN AND NRN TX/SERN
OK/SWRN AR AND FAR NWRN LA...REF WW 603. THUNDERSTORMS HAVE RECENTLY
DEVELOPED NEAR DFW AREA ON NRN EDGE OF DEWPOINT GRADIENT. OTHER
STORMS ARE LIKELY TO DEVELOP IN THICKER CU FIELD LOCATED
SOUTH/SOUTHEAST OF THESE STORMS. 12Z WRF-NMM IS SUGGESTIVE OF STORMS
NEAR DFW/NRN TX EVENTUALLY DEVELOPING A COLD POOL AND SURGING SSEWD
INTO STRONGER INSTABILITY. ORGANIZED OUTFLOW INTO THE HOT AND MOIST
BOUNDARY LAYER WOULD BE SUPPORTIVE OF MOSTLY WIND DAMAGE...THOUGH
-10C AT 500 MB AND STRONG INSTABILITY WILL ALSO SUPPORT HAIL.
OTHER STORMS HAVE ALSO DEVELOPED ACROSS PORTIONS OF SERN OK...ALONG
A WEAK BOUNDARY THAT STRETCHED FROM NEAR OKC TO HOT. RUC SHOWS
INSTABILITY INCREASING ACROSS THIS REGION INTO THE EVENING HOURS.
VEERING WIND PROFILES INDICATE THE POTENTIAL FOR CONTINUED STORM
DEVELOPMENT.
...SD/WRN ND...
SLIGHT RISK IN THE CENTRAL PLAINS HAS BEEN EXTENDED NWD ACROSS WRN
SD AND INTO WRN ND. AFTERNOON VISIBLE IMAGERY SHOWS UPPER IMPULSE IN
NWRN WY AND WLY WINDS ALOFT WILL CARRY THIS FEATURE EWD ACROSS SD
THIS EVENING. INCREASING LARGE SCALE LIFT AND MOISTURE/INSTABILITY
WILL BE FAVORABLE FOR STORMS WITH HAIL AND WIND DAMAGE OVER SD AND
PORTIONS OF ND THIS EVENING.
OTHERWISE...REST OF FORECAST ON TRACK WITH ONLY VERY MINOR
ADJUSTMENTS TO THUNDER/SEVERE LINE BASED ON CURRENT TRENDS.
..IMY.. 07/19/2009
.PREV DISCUSSION... /ISSUED 1125 AM CDT SUN JUL 19 2009/
...CENTRAL AND SRN HIGH PLAINS...
PATTERN HAS CHANGED LITTLE IN THIS ZONE WITH NWLY FLOW ON E SIDE OF
LARGE SWRN U.S. UPPER HIGH. THIS MAINTAINS A FAVORABLE SHEAR
PROFILE FOR SEVERE STORM POTENTIAL IN AREAS OF FAVORABLE INSTABILITY
AND LOW LEVEL CONVERGENCE. 25-30KT SLY LOW LEVEL FLOW IS INCREASING
BOUNDARY LAYER MOISTURE NWD THRU CENTRAL HIGH PLAINS TO E OF LEE
TROUGH WITH DEWPOINTS RISING INTO THE 60S THIS AFTERNOON AS FAR N AS
SRN SD. ONCE MAX HEATING IS REACHED BY MID AFTERNOON...STEEP LAPSE
RATES AND LITTLE REMAINING CINH COUPLED WITH MLCAPES AOA 2000 J/KG
SHOULD SUPPORT DEVELOPMENT OF SEVERE THUNDERSTORMS. STORMS
INITIALLY WILL BE WIDELY SCATTERED GIVEN THE WEAK LOW LEVEL
CONVERGENCE AND LIMITED LARGE SCALE ASCENT...HOWEVER PARAMETERS
EXPECTED TO BE IN PLACE FOR SUPERCELLS. LARGE HAIL WILL BE PRIMARY
THREAT ALONG WITH DOWNBURST POTENTIAL GIVEN DCAPE UPWARDS TO 1500
J/KG.
STORMS WILL LIKELY INITIATE OFF THE HIGHER TERRAIN VICINITY LEE
TROUGH AND THEN DEVELOP/PROPAGATE SEWD MOST ANYWHERE FROM SRN SD TO
W TX/ERN NM BORDER REGION. WITHIN THIS REGION THERE IS POTENTIAL FOR
A HIGHER PROBABILITY OF SEVERE COVERAGE INCLUDING A SIG HAIL
AREA...BUT CONFIDENCE TOO LOW ATTM TO INDICATE WHERE.
...NRN PLAINS...
A SIGNIFICANT S/WV TROUGH TOPPING STRONG WRN UPPER HIGH CURRENTLY
MOVING E ACROSS SWRN CANADA...WILL BEGIN TO BRING STRONG FLOW AND
MID LEVEL COOLING INTO NRN HIGH PLAINS LATE TODAY/TONIGHT. A NARROW
ZONE OF INCREASING MOISTURE/INSTABILITY WILL DEVELOP NWD ACROSS ND
THIS AFTERNOON AHEAD OF SURFACE COLD FRONT CURRENTLY MOVING SEWD
ACROSS SRN SASKATCHEWAN INTO NRN MT. BY THIS EVENING THUNDERSTORMS
WILL DEVELOP ALONG/AHEAD OF COLD FRONT INTO WRN ND WHERE MLCAPES
WILL BE INCREASING TO AOA 1500 J/KG. WITH STEEP LAPSE RATES AND
40-50KT OF DEEP LAYER SHEAR...A FEW THUNDERSTORMS ARE LIKELY. AREA
WILL NEED TO BE MONITORED FOR A POSSIBLE UPGRADE TO SLIGHT THIS
AFTERNOON IF GREATER INSTABILITY THAN NOW EXPECTED CAN DEVELOP.
...SRN AZ...
AGAIN TODAY VERY HOT TEMPERATURES AND NEARLY ADIABATIC LAPSE RATES
TO 500 MB...WILL LEAD TO STRONG OUTFLOW FROM ANY HIGH BASED
THUNDERSTORMS THAT IMPINGE ON DESERT VALLEYS THIS AFTERNOON/EVENING.
THERMODYNAMICS HAVE CHANGED LITTLE SINCE SATURDAY OTHER THAN FULL
HEATING IS EXPECTED ACROSS MUCH OF AZ WITH LITTLE TO NO MORNING
CLOUD COVER. MLCAPES OVER DESERTS VALLEYS EXPECTED TO BE GENERALLY
LESS THAN 500 J/KG...HOWEVER DCAPES OF 2000 J/KG SUPPORT THE
STRONG/ISOLATED SEVERE WIND POTENTIAL FROM ANY STORM THAN
MOVES/DEVELOPS OFF THE HIGHER TERRAIN.
...CENTRAL/SRN FL...
A BROAD UPPER TROUGH IS MOVING SLOWLY EASTWARD ACROSS THE EASTERN
STATES...WITH BASE OF TROUGH MOVING ACROSS THE GULF OF MEXICO TOWARD
FL. RELATIVELY COOL TEMPERATURES ALOFT AND 70S DEWPOINTS AT THE
SURFACE WILL PROMOTE NUMEROUS THUNDERSTORMS THIS AFTERNOON AND
EVENING. A FEW OF THE STORMS MAY PRODUCE LOCALLY DAMAGING WINDS.
...VICINTY YELLOWSTONE N.P...
MID/HIGH LEVEL MOISTURE AHEAD OF A WEAK UPPER IMPULSE MOVING EWD
ACROSS NRN INTERMOUNTAIN REGION SHOULD PROVIDE SUPPORT FOR SCATTERED
HIGH BASED THUNDERSTORMS THIS AFTERNOON. SURFACE BASED STORMS WILL
INITIATE OVER HIGHER MTNS AND PRIMARILY HAVE POTENTIAL FOR STRONG
LOCALLY DAMAGING WINDS GIVEN THE DCAPES AROUND 1000 J/KG AND 30-40KT
OF MID LEVEL FLOW.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment