SPC AC 041620
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT FRI JUL 04 2008
VALID 041630Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS NRN ROCKIES INTO A LARGE PART
OF MT...
...NRN RCKYS...
PROGRESSIVE SHORTWAVE TROUGH NOW PUSHING INLAND ACROSS THE PAC NW
WILL CONTINUE EWD INTO THE NRN ROCKIES WITH SOMEWHAT OF A POSITIVE
TILT TODAY. AHEAD OF THIS...MORE SUBTLE WAVE EJECTING NNEWD ACROSS
NRN NV ATTM WILL LIFT INTO SWRN/CENTRAL MT. IN RESPONSE TO
APPROACHING SYSTEMS...ELONGATED SURFACE LOW/TROUGH WILL DEVELOP JUST
EAST OF THE CONTINENTAL DIVIDE DURING THE AFTERNOON...WHICH WILL
BECOME MORE DEFINED LATE TODAY AS N-S ORIENTED COLD FRONT SHIFTS EWD
INTO THE NRN HIGH PLAINS. SLIGHT INCREASE IN ESELY LOW LEVEL FLOW
EAST OF THE SURFACE TROUGH SHOULD ALLOW RICHER MOISTURE IN PLACE
OVER ERN MT THIS MORNING TO ADVECT WNWWD THROUGH THE DAY.
STRONG HEATING AND STEEP MID LEVEL LAPSE RATES COMBINED WITH
THE INCREASING MOISTURE WILL YIELD SBCAPE AOA 1500 J/KG BY MID/LATE
AFTN FROM CNTRL ID NE INTO NW MT. TSTMS SHOULD FORM THIS AFTN FIRST
OVER THE HIGHER TERRAIN OF NRN ID/WRN MT...AND THEN ALONG COLD FRONT
PERHAPS AS FAR SW AS SW ID. SUPERCELLS WITH LARGE HAIL AND DAMAGING
WINDS WILL BE POSSIBLE AHEAD OF THE FRONT...ESPECIALLY JUST E OF THE
MOUNTAINS IN MT WHERE 40+ KT DEEP SW SHEAR WILL PREVAIL. WITH
TIME...STRENGTHENING COLD POOL POTENTIAL AND FORCING ASSOCIATED WITH
SRN PART OF APPROACHING UPPER TROUGH SHOULD SUPPORT EVOLUTION INTO A
LINEAR BAND OR TWO OF STORMS. THE ACTIVITY SHOULD MOVE RAPIDLY NE
TOWARD THE CANADIAN BORDER THIS EVENING WITH THE POTENTIAL FOR HIGH
WIND/HAIL.
...AZ...
AFTER A FAIRLY ACTIVE CONVECTIVE DAY OVER THE LWR DESERTS OF S CNTRL
AND SE AZ YESTERDAY...ANOTHER ACTIVE DAY APPEARS TO BE ON THE WAY.
12Z SOUNDINGS INDICATE ELY FLOW HAS STRENGTHENED OVER THE PAST 24
HOURS AT BOTH PHX AND TUS...WITH GREATER MOISTURE ALSO IN PLACE
THROUGHOUT DEEP BOUNDARY LAYER. MID/UPPER LEVEL RIDGE IS FORECAST
TO SHIFT A BIT EWD THROUGH THE DAY AS TROUGH AMPLIFIES OVER THE PAC
NW...WHICH MAY WEAKEN WINDS A BIT AND SUSTAIN A MORE ELY COMPONENT
TO STEERING FLOW AS COMPARED TO THE PAST FEW DAYS.
EXPECT HEATING WILL GENERATE INCREASING MOIST CONVECTION OVER HIGHER
TERRAIN LATE TODAY...YIELDING THREATS OF ISOLATED DAMAGING WINDS AND
HAIL AS ACTIVITY DEVELOPS WWD THROUGH THE LATE EVENING.
...MID-ATLC/SERN STATES WWD INTO AR/ERN OK...
WEAK FRONT...PRE-FRONTAL OUTFLOW BOUNDARIES...AND/OR DIFFERENTIAL
HEATING BOUNDARIES WILL SERVE AS FOCI FOR DIURNALLY-ENHANCED STORMS
FROM THE MID MS/LWR OH VLY REGION TO THE MID ATLANTIC CST TODAY.
DEEP SHEAR WILL REMAIN MODEST /AOB 30 KTS/ BENEATH BELT OF MODEST
CYCLONIC FLOW ALOFT. SATELLITE AND VWP DATA ATTM DO NOT SHOW ANY
IDENTIFIABLE IMPULSES TO ENHANCE UVV...ALTHOUGH SUCH FEATURES MIGHT
BE MASKED BY CONVECTIVE DEBRIS. THE STRONGEST STORMS SHOULD OCCUR
IN AREAS RECEIVING GREATEST HEATING/ CONVERGENCE ON SRN EDGE OF
STRONGER MID LEVEL FLOW....I.E. FROM MIDDLE/ERN TN INTO SRN KY...AND
FROM CNTRL/ERN VA INTO SRN MD/DE AND PERHAPS NC. WEAK MID LEVEL
LAPSE RATES AND MODEST WIND FIELDS SHOULD LIMIT OVERALL SVR RISK.
HOWEVER...ONE OR TWO CORRIDORS OF LOCALLY-ENHANCED SVR RISK /IN THE
FORM OF DMGG WIND GUSTS/ CAN BE EXPECTED ACROSS THIS BROAD REGION.
..EVANS/SMITH/CORFIDI.. 07/04/2008
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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