SPC AC 041253
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CDT FRI JUL 04 2008
VALID 041300Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN RCKYS...
...SYNOPSIS...
UPR RIDGE WILL REMAIN MORE OR LESS STNRY OVER THE FOUR CORNERS THIS
PERIOD AS NWRN FLANK IS TEMPORARILY FLATTENED BY POSITIVE TILT
TROUGH NOW OVER WRN WA/ORE AND NW CA. THE TROUGH SHOULD CONTINUE NE
INTO THE NRN GRT BASIN/NRN RCKYS BY 12Z SATURDAY. DOWNSTREAM FROM
THE RIDGE...ALTHOUGH MAIN BELT OF THE WLYS WILL REMAIN IN CANADA...
A BAND OF MODEST CYCLONIC FLOW WILL PREVAIL FROM THE LWR MO VLY INTO
THE MID/LWR OH VLY.
AT THE SFC...A FAIRLY WELL-DEFINED COLD FRONT WILL MOVE E ACROSS MT
AND THE NRN GRT BASIN...AHEAD OF WA/ORE UPR TROUGH. A WEAKER
BOUNDARY NOW EXTENDING FROM THE DELMARVA PENINSULA WSW INTO THE
OZARKS WILL SETTLE SLOWLY S INTO THE LWR OH/TN VLYS...BUT REMAIN
NEARLY STNRY ALONG THE E CST.
...NRN RCKYS...
NRN PART OF AFOREMENTIONED TROUGH WILL EDGE E INTO NRN ID/NW MT
LATER TODAY. SECONDARY IMPULSE NOW ENTERING NW CA SHOULD REACH NW
NV BY EVENING BEFORE CONTINUING NE INTO ERN ID/WRN MT TONIGHT/EARLY
SATURDAY. AHEAD OF THESE FEATURES...LOW/MID-LVL MOISTURE WILL
INCREASE OVER THE NRN RCKYS AS A RESULT OF BOTH ADVECTION AND
RECYCLING OF MOISTURE FROM PREVIOUS CONVECTION.
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 HAIL...HIGH WINDS AND
MARGINALLY SVR HAIL 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...GOOD COLD POOL POTENTIAL AND FORCING
ASSOCIATED WITH SRN PART OF APPROACHING UPR TROUGH SHOULD SUPPORT
EVOLUTION INTO A 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.
MODEST ELY FLOW...SLIGHTLY VEERED AND WEAKER COMPARED WITH
YESTERDAY...SHOULD EXIST OVER THE SRN HALF OF THE STATE. THROUGH A
DEEP LAYER...SATELLITE AND GPS PW DATA SHOW AMPLE MOISTURE PRESENT
FOR ROBUST STORMS. IN ADDITION...LOW LEVEL MOISTURE HAS INCREASED
FROM THE S OVER THE LOWER DESERTS. OVERALL SETUP APPEARS FAVORABLE
FOR A ROUND OR TWO OF FAIRLY WIDESPREAD STORMS. THESE COULD YIELD
ISOLD DMGG WIND GUSTS/SVR HAIL...IN ADDITION TO AN INCREASED RISK
FOR HEAVY RAIN...AND COULD PERSIST INTO LATE TONIGHT.
...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 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/ MAY BECOME MORE CLEARLY DEFINED A BIT LATER TODAY.
..CORFIDI/JEWELL.. 07/04/2008
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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