SPC AC 021605
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1105 AM CDT WED JUL 02 2008
VALID 021630Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL HIGH
PLAINS...ACROSS THE MID MS VALLEY...INTO THE GREAT LAKES REGION...
...MID MS VALLEY INTO THE GREAT LAKES...
THUNDERSTORMS HAVE INTENSIFIED THIS MORNING SRN WI IN RESPONSE TO
BOTH THE STRONG TROUGH SWINGING EWD ACROSS THE UPPER GREAT LAKES AND
RAPIDLY INCREASING MOISTURE/INSTABILITY IN ADVANCE OF THE COLD
FRONT. WITH COMBINATION OF HEATING AND MOISTURE ADVECTION...AIR
MASS AHEAD OF THE FRONT WHICH IS CURRENTLY FROM NRN WI SWWD INTO NRN
IA AND THEN WWD NEAR KS/NEB BORDER...WILL BECOME MDTLY TO STRONGLY
UNSTABLE THIS AFTERNOON WITH MLCAPES RANGING UPWARD FROM 1500-2000
J/KG GREAT LAKES TO NEAR 3000 J/KG LWR MO TO CENTRAL PLAINS.
THUNDERSTORMS WILL BECOME INCREASINGLY WIDESPREAD THIS AFTERNOON AS
THE HEATING ELIMINATES CONVECTIVE INHIBITION. 40-50KT OF SHEAR WILL
SUPPORT FORWARD PROPAGATING COLD POOLS AND WIND DAMAGE ACROSS THE MI
AND NRN OH VALLEY PORTION OF THE SLIGHT RISK. FURTHER W THE SHEAR IS
SOMEWHAT WEAKER...HOWEVER WITH THE EXPECTED INSTABILITY THERE WILL
BE MULTICELLULAR STORMS AND POTENTIAL FOR SUPERCELLS. LARGE HAIL
AND DAMAGING WINDS WILL BE THE PRIMARY THREAT...HOWEVER ANY
SUPERCELL WOULD ALSO POSE AN ENHANCED SEVERE THREAT INCLUDING
ISOLATED TORNADOES UNTIL EVENING.
...CENTRAL HIGH PLAINS...
SOUTHEASTERLY UPSLOPE FLOW PATTERN IS FORECAST TO DEVELOP THIS
AFTERNOON FROM THE BEAR TOOTH MTNS OF SCENTRAL MT/BIGHORN MTNS OF WY
INTO NORTHEAST CO. IT APPEARS LIKELY THAT DEWPOINTS IN THE 50S AND
STEEP MID LEVEL LAPSE RATES OVER THIS REGION WILL YIELD AFTERNOON
MLCAPE VALUES OF 1500-1800 J/KG. ALL MODELS ARE CONSISTENT IN
DEVELOPING SCATTERED THUNDERSTORMS ALONG THIS AXIS AND TRACKING
ACTIVITY SOUTHEASTWARD ACROSS ERN WY INTO THE NEB PANHANDLE DURING
THE EVENING. DESPITE RATHER WEAK LOW LEVEL WINDS...VEERING WITH
HEIGHT AND FAVORABLE MID/UPPER LEVEL FLOW WILL PROVIDE SUFFICIENT
EFFECTIVE SHEAR FOR A RISK OF SUPERCELLS. LARGE HAIL AND DAMAGING
WINDS WILL BE POSSIBLE...ALONG WITH AN ISOLATED TORNADO.
...SRN ROCKIES...
DIURNAL STORMS WILL DEVELOP ALONG THE COMPLEX TERRAIN WITHIN A STEEP
LAPSE RATE ENVIRONMENT. THE DEEPLY MIXED BOUNDARY LAYER CONDITIONS
WITH DCAPES AOA 1000 J/KG SUGGEST THE POTENTIAL FOR A FEW STRONG
WIND GUSTS AS STORMS PROPAGATE TOWARD LOWER ELEVATIONS.
...PACIFIC NW...
FORCING FOR ASCENT ASSOCIATED WITH A SHORT WAVE TROUGH LIFTING NEWD
ALONG THE PACIFIC NW COAST COMBINED WITH OROGRAPHIC EFFECTS WILL
RESULT IN SCATTERED TSTM DEVELOPMENT THIS AFTERNOON INTO TONIGHT
OVER THE CASCADES...PERHAPS INTO COLUMBIA BASIN. CONVECTIVE
INSTABILITY IS FORECAST TO REMAIN SOMEWHAT MARGINAL...BUT THE
PRESENCE OF RELATIVELY STEEP LAPSE RATES SUGGESTS THE POTENTIAL FOR
A FEW STRONG STORMS CAPABLE OF HAIL AND STRONG WIND GUSTS.
...FL...
VERY MOIST BOUNDARY LAYER CONDITIONS AND RELATIVELY COOL
TEMPERATURES ALOFT WILL ONCE AGAIN CONTRIBUTE TO THE DEVELOPMENT OF
MODERATE INSTABILITY THIS AFTERNOON WITH MLCAPES OF 1000-2000 J/KG.
DIURNAL STORMS ARE EXPECTED TO BECOME FOCUSED ALONG STRENGTHENING
SEA BREEZE CIRCULATIONS WHERE LOCALLY STRONG WET MICRO BURST
ACTIVITY IS POSSIBLE.
...NEW ENGLAND...
NEWD MOVEMENT OF MIDLEVEL THERMAL TROUGH COMBINED WITH DEWPOINTS IN
THE 60S WILL RESULT IN POCKETS OF MODERATE INSTABILITY TODAY WITH
MLCAPES OF 1000 J/KG. SCATTERED...DIURNAL TSTM DEVELOPMENT IS
EXPECTED BY AFTERNOON ALONG REMNANT SURFACE BOUNDARY WITHIN
KINEMATIC ENVIRONMENT EXHIBITING STRONG UPPER TROPOSPHERIC
WINDS...BUT GENERALLY WEAK MID TO LOWER-LEVEL FLOW. A FEW OF THE
STRONGER STORMS WILL BE CAPABLE OF STRONG WIND GUSTS AND SOME HAIL
INTO THIS EVENING.
..HALES/LEVIT.. 07/02/2008
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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