Friday, June 29, 2012

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 291938
SWODY1
SPC AC 291937

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0237 PM CDT FRI JUN 29 2012

VALID 292000Z - 301200Z

...THERE IS A MDT RISK OF SVR TSTMS FROM E CNTRL IND EWD ACROSS
OH...WV...AND SWRN PA...

...THERE IS A SLGT RISK OF SVR TSTMS FROM IA SEWD TO THE DELMARVA...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS NRN NEW ENGLAND...

...UPGRADED TO A MODERATE RISK FOR PORTIONS OF IND...OH...WV AND SW
PA...

...INDIANA SEWD TO THE DELMARVA...
AN MCS CONTINUES TO GROW UPSCALE ACROSS INDIANA...WHERE WINDS WERE
RECENTLY MEASURED AT 91 MPH. AN EXTREMELY UNSTABLE AIR MASS IS IN
PLACE AHEAD OF THIS SYSTEM...ALL THE WAY TO THE ATLANTIC COAST.
ALTHOUGH MEAN WINDS ALOFT ARE ON THE MARGINS FOR MORE SIGNIFICANT
EVENTS...LAPSE RATES ARE VERY STEEP WITH PEAK HEATING BEING
ACHIEVED. THIS SYSTEM SHOULD CONTINUE TO FORWARD PROPAGATE EWD AND
SEWD THROUGH THE EVENING...AND GIVEN LACK OF APPRECIABLE CIN
FORECAST THIS EVENING...THE SYSTEM MAY CONTINUE TO THE COAST. THE
GREATEST THREAT FOR SIGNIFICANT WINDS WILL BE FROM IND TO WV.

FOR MORE INFORMATION SEE MESOSCALE DISCUSSION 1306.

...SD/NEB/IA...
REMOVED SLIGHT RISK FROM ERN SD AS OUTFLOW HAS STABILIZED A LARGE
PORTION OF THE AREA. ISOLATED SEVERE MAY OCCUR OVERNIGHT BUT WARM
ADVECTION WILL BE MITIGATED BY CAPPING. TO THE SE...AN MCV CONTINUES
EWD ACROSS CNTRL IA...WITH STRONG INSTABILITY TO THE E. A
REGENERATION OF CONVECTION IS LIKELY AHEAD OF THIS MCV WITH WIND AND
HAIL POSSIBLE.

ELSEWHERE...LITTLE CHANGE WAS MADE TO THE PREVIOUS OUTLOOK.

..JEWELL.. 06/29/2012

.PREV DISCUSSION... /ISSUED 1114 AM CDT FRI JUN 29 2012/

...NRN PLNS/MID MO VLY TO THE MID ATLANTIC COAST...
STILL A FAIR DEGREE OF UNCERTAINTY ON CONVECTIVE EVOLUTION FOR THIS
AFTN/TONIGHT. AN ONGOING CLUSTER OF ELEVATED TSTMS HAS EVOLVED OVER
NRN IL LATE THIS MORNING IN A REGION OF MODEST LLVL WARM ADVECTION.
LATEST SSEO GUIDANCE MAINTAINS THIS CLUSTER...DEVELOPING ROBUST
STORMS THROUGH THE CAPE AXIS AND INTO THE CNTRL APLCNS LATER THIS
EVENING. 12Z NAM IS NOT AS STRONG AND SUGGESTS THAT CONVECTION WILL
FESTER FOR SVRL HRS OVER THE MIDWEST.

AIR MASS ALONG/S OF A E-W ORIENTED BOUNDARY JUST N OF THE OH RVR IS
MOIST AND VERY UNSTABLE OWING TO MID 60S BOUNDARY LAYER DEW POINTS
BENEATH H7-H5 LAPSE RATES NEAR 9 DEG C PER KM. AS THE BOUNDARY
MOVES SLOWLY NWD EARLY THIS AFTN...IT APPEARS THAT THE SSEO SCENARIO
FITS BEST WITH STORMS EXPECTED TO DEVELOP ESE ALONG N EDGE OF THE
MLCAPE AXIS /4000-6000 J PER KG/. ONCE A SUBSTANTIAL COLD POOL CAN
BECOME ESTABLISHED...DMGG WIND GUSTS WILL BE LIKELY ALONG WITH VERY
LARGE HAIL. HIGHEST SVR POTENTIAL IS LIKELY TO BE FROM NRN IL/IND
ESE INTO PARTS OF THE MID-OH VLY. ESE EXTENT OF THE SVR THREAT
SHOULD BE LIMITED TO AREAS W OF THE APLCN MOUNTAINS BY LATE TONIGHT.


FARTHER TO THE NW...ONE OR MORE CLUSTERS OF TSTMS WILL LIKELY EVOLVE
IN ASSOCIATION WITH ANOTHER MCV OVER THE MID-MO VLY AND A SYNOPTIC
SCALE SYSTEM OVER ERN SD. AIR MASS DOWNSTREAM FROM THESE FEATURES IS
COMPARATIVELY MORE STABLE THAT AREAS FARTHER E. HOWEVER...DMGG
WIND/HAIL THREATS ARE NON-ZERO...ESPECIALLY ACROSS PORTIONS OF IA.


...NRN NEW ENGLAND...
HAVE UPGRADED PORTIONS OF NRN NEW ENGLAND TO A SLIGHT RISK FOR THIS
AFTN AND EVE. WATER VAPOR IMAGERY SHOWS A MID-LVL SHORTWAVE TROUGH
MIGRATING ACROSS ERN ONT AND SWRN QUEBEC. AS THE BASE OF THIS
FEATURE GRAZES NRN NEW ENGLAND...EXPECT SCTD TSTMS TO DEVELOP...BOTH
ALONG THE HIGHER TERRAIN AND A RETREATING WRMFNT. STRAIGHT LINE
HODOGRAPHS WITH 0-6KM SHEAR OF 35-40 KTS WILL BE FAVORABLE FOR
DISCRETE SUPERCELL STORMS WITH LARGE HAIL AND DMGG WIND GUSTS.
ACTIVITY SHOULD DIMINISH AFTER DARK.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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: