Thursday, May 6, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 061300
SWODY1
SPC AC 061259

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0759 AM CDT THU MAY 06 2010

VALID 061300Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL PLNS
AND MID MS VLY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A SMALL PART OF SRN NEW
ENGLAND...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE FL
PENINSULA...

...SYNOPSIS...
PAIR OF FAIRLY STRONG UPR TROUGHS...ONE OVER WRN QUE AND THE LWR GRT
LKS...AND THE OTHER OVER WY...WILL CONTINUE STEADILY E THROUGH FRI
AS FAST...PROGRESSIVE PATTERN PERSISTS OVER THE LWR 48.

COLD FRONT ASSOCIATED WITH ERN SYSTEM WILL MOVE OFF THE NEW ENGLAND
CST THIS AFTN...WHILE TRAILING WRN PART REDEVELOPS NWD AS A WARM
FRONT OVER KS/MO. CO LEE CYCLONE SHOULD SETTLE A BIT SE INTO SWRN
KS LATER TODAY...BEFORE TURNING NE TOWARD CNTRL MO EARLY FRI.
FARTHER S...REMNANT FRONTAL ZONE/PW GRADIENT LIKELY WILL LINGER OVER
CNTRL FL.

...CNTRL HI PLNS TO MID MS VLY LATE TODAY THROUGH EARLY FRI...
CO LEE CYCLONE SHOULD CONTINUE TO STRENGTHEN TODAY IN RESPONSE TO
BOTH SFC HEATING AND APPROACH OF WY UPR TROUGH. THIS WILL MAINTAIN
GRADUALLY-MOISTENING ELY FLOW N OF THE LOW INTO THE NRN CO RCKYS/HI
PLNS...AND SUPPORT STORM DEVELOPMENT OVER THE THAT AREA BY MID TO
LATE AFTN. ALTHOUGH THE ENVIRONMENT WILL BE STRONGLY SHEARED...IT
ALSO WILL BE RATHER MOISTURE STARVED...WITH PW REMAINING AOB .75
INCH. THUS...WHILE THE STORMS COULD YIELD SOME HAIL...OVERALL SVR
THREAT SHOULD REMAIN LIMITED.

MORE SUBSTANTIAL STORMS SHOULD FORM LATE IN THE DAY
AND...ESPECIALLY...JUST AFTER SUNSET OVER NWRN AND N CNTRL KS AS
SOMEWHAT RICHER MOISTURE /PW UP TO 1 INCH/ SPREADS NWD ATOP
STRENGTHENING W/E WARM FRONT. COMBINATION OF MID LVL COOLING AND
ASCENT WITH WY UPR TROUGH...AND 40+ KT SSWLY LLJ...SHOULD SUPPORT
UPSCALE DEVELOPMENT INTO A SIZABLE MCS. ADDITIONAL STORMS LIKELY
WILL BUILD N INTO NEB...AND E ALONG WARM/STNRY FRONT INTO NE KS AND
THE NRN HALF OF MO. THESE STORMS WILL HAVE ACCESS TO SUFFICIENT
ELEVATED CAPE /AOA 1500 J PER KG/ TO POSE A THREAT FOR LARGE HAIL
AND POSSIBLY DMGG WIND THROUGH EARLY FRI.

EML CAP AND MODEST MOISTURE AVAILABILITY/FORCING FOR ASCENT SHOULD
PRECLUDE SURFACE-BASED/WARM SECTOR STORMS OVER KS THIS AFTN.
HOWEVER...IF ANY SUCH ACTIVITY WERE TO FORM...CNTRL/E CNTRL KS
APPEAR TO BE THE MOST LIKELY AREAS GIVEN PROXIMITY OF SFC FRONT AND
RELATIVELY WEAK CINH PRESENT THERE.

...NERN U.S. THROUGH LATE AFTN..
COLD FRONT NOW OVER ERN PA/SE NY/NW NEW ENGLAND REMAINS WELL AHEAD
OF ASSOCIATED UPR TROUGH THAT ATTM APPEARS TO BE PASSING LK HURON.
THE TROUGH SHOULD ACCELERATE EWD TODAY AND ULTIMATELY LESSEN ITS
SEPARATION WITH THE FRONT AS THE BOUNDARY MOVES OFF THE NEW ENGLAND
CST THIS AFTN.

IN THE MEANTIME...FILTERED HEATING WILL OCCUR AHEAD OF THE FRONT
OVER SRN NEW ENGLAND THROUGH ABOUT MIDDAY...AND ALONG THE MID
ATLANTIC CST THROUGH MID AFTN...AS AXIS OF PRE-FRONTAL MOISTURE
SPREADS NEWD BENEATH STRENGTHENING WSW FLOW ALOFT.

COMBINATION OF INCREASING INSTABILITY AND SHEAR WITH RELATIVELY
STEEP LOW TO MID LVL LAPSE RATES SUGGESTS THAT TSTMS MAY FORM ALONG
AND AHEAD OF FRONT BEFORE THE BOUNDARY CLEARS THE NEW ENGLAND CST.
GIVEN STRENGTH OF DEEP LARGELY UNIDIRECTIONAL FLOW /AROUND 50 KTS AT
700 MB/...SETUP MAY YIELD A FEW BOWING SEGMENTS WITH HIGH WIND/HAIL.
WHILE THIS THREAT SHOULD END BY MID AFTN IN NEW ENGLAND...STRONGER
CINH AND SLOWER MOVEMENT OF FRONT SUGGEST LATER STORM DEVELOPMENT
AND A PERHAPS DELAYED SVR THREAT FARTHER S OVER THE DELMARVA
PENINSULA/LOWER CHESAPEAKE BAY.

...FL THIS AFTN...
WEAK LOW LATITUDE DISTURBANCE APPARENT IN WV IMAGERY WILL MOVE ESE
ACROSS THE FL PENINSULA TODAY...ALONG WITH AN ASSOCIATED AREA OF MID
LVL COOLING /500 MB TEMPS AOB MINUS 10 C/ AND ASCENT. DEEP SHEAR
WILL REMAIN WEAK. BUT COMBINATION OF UPR IMPULSE WITH STRONG SFC
HEATING AND AXIS OF ENHANCED PW/RESIDUAL FRONT SHOULD SUPPORT
NUMEROUS STRONG TO POSSIBLE SVR PULSE STORMS. LOW LVL UPLIFT LIKELY
WILL FOCUS ALONG SEA BREEZE BOUNDARIES...WITH DEVELOPMENT SPREADING
MAINLY N TO S OVER CNTRL/SRN PARTS OF THE PENINSULA. SVR HAIL AND
LOCALLY DMGG WIND MAY OCCUR THROUGH LATE AFTN.

..CORFIDI/GARNER.. 05/06/2010

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