SPC AC 191253
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CDT FRI MAY 19 2006
VALID 191300Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LWR MO VLY INTO THE TN
VLY...
...THERE IS A SLGT RISK OF SVR TSTMS OVER INTERIOR PARTS OF THE PAC
NW...
...SYNOPSIS...
AMPLIFIED PATTERN WILL CONTINUE OVER THE LWR 48 THIS PERIOD...WITH A
RIDGE OVER THE WRN SLOPES OF THE RCKYS AND A TROUGH FROM WRN HUDSON
BAY TO THE MID ATLANTIC CST. LEAD IMPULSE ASSOCIATED WITH E PACIFIC
TROUGH...NOW OFF THE NRN CA CST...SHOULD EJECT NNE INTO THE LWR
COLUMBIA BASIN BY 12Z SATURDAY AS UPSTREAM DISTURBANCE NOW NEAR
40N/135W DROPS SSE TO REPLACE IT. FARTHER E...SHORTWAVE IMPULSES
ARE SOMEWHAT HARDER TO DISCERN IN THE NW FLOW ACROSS THE PLAINS.
SATELLITE SUGGESTS THAT ONE DISTURBANCE ATTM IS OVER NW MO...WITH
ANOTHER OVER CNTRL ND. BOTH SHOULD SHEAR SEWD TODAY AS WRN PA UPR
LOW LIFTS NE INTO THE ADIRONDACKS.
...LWR MO VLY INTO TN VLY...
STATIONARY FRONTAL ZONE EXTENDING SEWD FROM THE LWR MO VLY INTO TN
AND THE SRN APLCNS WILL BE THE FOCUS FOR SCATTERED STORMS THIS
PERIOD. WHILE TIMING WITH RESPECT TO SHORTWAVE FEATURES DOES NOT
APPEAR TO BE FAVORABLE...WEAKENING CINH PROVIDED BY SURFACE HEATING
AND LIFT NEAR BOUNDARY SHOULD SUPPORT DEVELOPMENT OVER MO/AR AND W
TN DURING THE AFTERNOON. THIS ACTIVITY SHOULD MOVE/DEVELOP ESE AND
MAY EXPAND IN COVERAGE THROUGH LATE EVENING BEFORE DIMINISHING.
HAIL AND DAMAGING WIND GUSTS ARE POSSIBLE...BUT TORNADO THREAT
APPEARS MARGINAL GIVEN LIMITED MOISTURE AVAILABILITY.
CURRENT SURFACE OBSERVATIONS...GOES MICROWAVE SOUNDER PWS...AND AIR
MASS MOVEMENTS IN RECENT DAYS SUGGEST THAT THE MODELS ARE
OVER-FORECASTING BOUNDARY LAYER MOISTURE INVOF AFOREMENTIONED FRONT.
EVEN ACCOUNTING FOR MID-MAY EVAPOTRANSPIRATION...EXPECT THAT
SURFACE DEWPOINTS IN WELL MIXED ENVIRONMENT WILL AT BEST REMAIN
LIMITED TO THE LOW TO MID 50S FROM MO INTO NRN AR...WITH LESSER
VALUES EXTENDING E/SE INTO THE TN VLY.
NEVERTHELESS...RELATIVELY COOL MID LEVEL TEMPERATURES AND STRONG
SURFACE HEATING WILL CONTRIBUTE TO AN ENVIRONMENT OF STEEP /8-9 DEG
C PER KM/ LOW-MID LEVEL LAPSE RATES OVER MO/AR. COUPLED WITH EVEN
MODEST MOISTURE...THIS SHOULD YIELD MUCAPE OF 1000-1500 J/KG. GIVEN
EXPECTED FAVORABLE VERTICAL SHEAR PROFILES ASSOCIATED WITH NWLY
MID/UPR LEVEL FLOW...AND POSSIBLE INCREASE IN LARGE SCALE ASCENT TO
BE PROVIDED LATER TODAY BY UPR IMPULSE NOW IN ND...SETUP COULD
SUPPORT A FEW ROTATING STORMS WITH HAIL/HIGH WIND. SFC WINDS WILL
BE VARIABLE...RANGING FROM SWLY IN WARM SECTOR TO SLY-SELY JUST E OF
FRONT...RESULTING IN A LARGE VARIATION IN LOW LEVEL SHEAR PROFILES.
BUT BOWING STRUCTURES WILL BE POSSIBLE WITH ANY STORMS THAT DO FORM
GIVEN MODERATE MEAN FLOW AND LIKELY 20 DEG F TEMPERATURE-DEWPOINT
SPREADS.
...INTERIOR PAC NW...
WIND PROFILES WILL STRENGTHEN RELATIVE TO RECENT DAYS OVER INTERIOR
PORTIONS OF ORE/WA AND WRN ID LATER TODAY AS E PACIFIC SHORTWAVE
IMPULSE LIFTS NNE TOWARD REGION. SURFACE HEATING... POSSIBLY AIDED
BY LARGE SCALE ASCENT FROM SHORTWAVE...LIKELY WILL YIELD SCATTERED
AFTERNOON/EVENING STORMS OVER CNTRL/ERN ORE/WA AND POSSIBLY WRN
ID....INITIALLY OVER THE HIGHER TERRAIN. THE MODERATE...LARGELY
UNIDIRECTIONAL SSWLY CLOUD LAYER FLOW MAY SUPPORT DEVELOPMENT OF ONE
OR MORE BANDS OF STORMS. COUPLED WITH LARGE TEMPERATURE-DEWPOINT
SPREADS/STEEP LOW TO MID LEVEL LAPSE RATES...SOME OF THESE MAY
CONTAINING BOWING SEGMENTS WITH HIGH WIND/MARGINALLY SEVERE HAIL.
LOW LEVEL MOISTURE IN SOME SPOTS WILL BE AUGMENTED BY RECYCLING OF
MOISTURE FROM OVERNIGHT CONVECTION...AND COULD LOCALLY BOOST
AFTERNOON MUCAPE TO 1000 J/KG.
...NRN NJ TO SRN/CNTRL NEW ENGLAND...
LINGERING AXIS OF LOW LEVEL CONFLUENCE IN SW QUADRANT OF RI/ERN MA
SURFACE LOW MAY BE A FOCUS FOR TSTM DEVELOPMENT LATER TODAY AS
MODEST AIR MASS RECOVERY OCCURS IN WAKE OF DENSE MORNING
CLOUDS/PRECIP. GIVEN COLD MID LEVEL TEMPERATURES /BLO MINUS 20C AT
500 MB/... SOME OF THESE MAY PRODUCE HAIL AS MLCAPE CLIMBS TO AROUND
500 J/KG. STRONG-SVR TSTM POTENTIAL SHOULD DIMINISH WITH ONSET OF
DIURNAL COOLING.
..CORFIDI/TAYLOR.. 05/19/2006
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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