Thursday, April 1, 2010

DAY1SVR: Day 1 Convective Outlook Resent 1

ACUS01 KWNS 011223
SWODY1
SPC AC 011222

DAY 1 CONVECTIVE OUTLOOK RESENT 1
NWS STORM PREDICTION CENTER NORMAN OK
0722 AM CDT THU APR 01 2010

VALID 011300Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NWRN TX...WRN AND
NRN OK...AND SRN KS...

...SYNOPSIS...
HIGH AMPLITUDE FLOW REGIME ACROSS THE CONUS THIS PERIOD WITH
PROGRESSIVE LARGE-SCALE TROUGH AND ASSOCIATED STRONG HEIGHT FALLS
FORECAST TO SPREAD EAST FROM SRN CA TO SRN/CNTRL PLAINS THROUGH
EARLY FRIDAY. RIDGING...SURFACE AND ALOFT...WILL EXIST DOWNSTREAM
FROM THE WRN TROUGH AND CONTRIBUTE TO WARMER AND DRIER CONDITIONS
FROM THE MS VALLEY TO THE EAST COAST.

LEE CYCLOGENESIS WAS ALREADY UNDERWAY OVER NERN CO AND A DEEPENING
SURFACE LOW SHOULD CONSOLIDATE ACROSS NEBRASKA THIS EVENING BEFORE
TRACKING NEWD ALONG STRENGTHENING WARM FRONT FROM THE ERN DAKOTAS
INTO NRN MN. TRAILING COLD FRONT WILL DEVELOP EAST FROM THE
CNTRL/SRN HIGH PLAINS LATE TONIGHT...EVENTUALLY MERGING WITH
LEE-TROUGH/RESIDUAL DRYLINE VICINITY SRN KS...NRN AND WRN OK...AND
NWRN TX AREA BY FRIDAY MORNING.

...TX/OK/KS OVERNIGHT/EARLY FRIDAY...
MASS ADJUSTMENT IN RESPONSE TO APPROACHING LARGE-SCALE TROUGH WILL
PROVOKE INTENSIFICATION OF LOW LEVEL SLY FLOW ACROSS THE PLAINS
THROUGH TODAY. MEANWHILE...STRENGTHENING DEEP-LAYER SWLY FLOW ALOFT
AND INCREASING LARGE SCALE ASCENT WILL CONTRIBUTE TO STEEPENING
LAPSE RATES AND THE DEVELOPMENT OF A NARROW CORRIDOR OF MODEST
CONVECTIVE INSTABILITY /MUCAPE AROUND 1000 J PER KG/ FROM THE RIO
GRANDE VALLEY TO KS BY EVENING. STOUT EML PLUME SHOULD EFFECTIVELY
CAP MARGINALLY MOIST LOW LEVEL PARCELS FROM REACHING AN LFC UNTIL
WELL AFTER DARK WHEN STRONGER FORCING WITH THE SHORT WAVE TROUGH AND
FRONT ARRIVE OVER THE AREA FROM NWRN TX TO KS.

GIVEN CORRIDOR OF ANTECEDENT INSTABILITY/MUCAPE AROUND 1000 J PER KG
AND INTENSIFYING MID LEVEL FLOW CONTRIBUTING TO STRONG CLOUD-BEARING
SHEAR...A FEW SEVERE STORMS WITH LARGE HAIL APPEAR POSSIBLE PRIOR TO
DAYBREAK. ONLY LOW PROBABILITY SEVERE WIND/TORNADO THREATS ARE
EXPECTED WITH THIS ACTIVITY DUE TO LIMITED MAGNITUDE AND AREAL
EXTENT OF SURFACED-BASED INSTABILITY.

...DAKOTAS/NRN MN...
PRONOUNCED QG FORCING FOR ASCENT WILL EVOLVE WITHIN COUPLED-JET
REGION FROM THE DAKOTAS TO MN THROUGH LATE THIS AFTERNOON. AS THE
LARGER SCALE CYCLONE DEVELOPS NEWD FROM NEBRASKA...FORCED ASCENT
ACROSS THE WARM FRONT IS EXPECTED TO AID TSTM DEVELOPMENT ON THE
COOL SIDE OF THIS BOUNDARY FROM LATE AFTERNOON THROUGH TONIGHT.
PRESENCE OF MODEST INSTABILITY FEEDING THIS CONVECTION...ALONG WITH
STRONG SHEAR AND FORCING IN THIS ZONE...SUGGEST THAT HAIL IS
POSSIBLE WITH A FEW OF THESE STORMS. SOMEWHAT MARGINAL LAPSE
RATES...AND SPC HAIL GUIDANCE...SUGGEST THAT HAIL SIZE MAY BE
LIMITED TO LESS THAN 1 INCH WITH THE BULK OF THIS CONVECTION.

..CARBIN/JEWELL.. 04/01/2010

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