ACUS01 KWNS 281959
SWODY1
SPC AC 281957
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT SAT APR 28 2007
VALID 282000Z - 291200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN ROCKIES
INTO SWRN TX...
..SERN AZ EWD INTO SWRN TX...
SONORAN UPR LOW WILL BEGIN A SLOW EJECTION ENEWD TOWARD THE AZ/NM
BORDER BY 12Z. SEVERAL SHORTWAVE TROUGHS WERE ROTATING AROUND THE
LOW. ONE WAS MOVING INTO SERN AZ WITH AN UPSTREAM IMPULSE
APPROACHING THE SRN NM/SWRN TX INTERNATIONAL BORDER THIS AFTN.
RELATIVELY STEEP LAPSE RATES ALOFT...DIFFERENTIAL HEATING ALONG THE
HIGHER TERRAIN AND INJECTION OF MODEST LOW-LEVEL BOUNDARY LAYER
MOISTURE FROM THE PLAINS HAVE BEEN INSTRUMENTAL IN TSTM
DEVELOPMENT...FOCUSING VCNTY THE AFOREMENTIONED SHORTWAVE TROUGHS.
VERTICAL SHEAR ACROSS SERN AZ...SRN NM AND FAR W TX IS RATHER WEAK.
BUT...DEEP ELY TRAJECTORIES THROUGH THE TROPOSPHERE AND RELATIVELY
DRY SUB-CLOUD LAYER WILL BE FAVORABLE FOR GUSTY/DAMAGING WINDS AND
BLOWING DUST AS THE STORMS MOVE WWD INTO SWRN NM/SERN AZ. HAIL MAY
ACCOMPANY THE STRONGER STORMS.
FARTHER E ACROSS SWRN TX...LOW-LEVEL MOISTURE CONTINUES TO ADVECT
NWWD AND UPSLOPE INTO THE TRANSPECOS...BIG BEND AND STOCKTON PLATEAU
REGIONS. CLOUD-COVER HAS BEGUN TO THIN WITH INSOLATION INCREASING.
SCT TSTMS ARE EXPECTED TO DEVELOP LATE THIS AFTN...MAINLY ALONG THE
DAVIS...GLASS...CHISOS MOUNTAINS NWD TO PERHAPS THE GUADALUPES IN SE
NM. HERE...VERTICAL SHEAR WAS STRONGER AND MORE ROBUST STORM
STRUCTURES MAY YIELD LARGE HAIL AND PERHAPS DAMAGING WINDS.
SPORADIC BURSTS OF TSTMS MAY CONTINUE OVERNIGHT OVER THE SAME
GENERAL AREAS...BUT THE SVR THREATS SHOULD DIMINISH AFTER DARK.
..SCNTRL/S TX...
THE SEABREEZE AND WEAK INVERTED TROUGH ACROSS THE COASTAL PLAINS OF
SCNTRL/S TX WILL BE THE FOCI FOR ISOLD-WDLY SCT TSTMS THROUGH
MID-EVENING AS INHIBITION IS WEAKENED BY HEATING/CONVERGENCE. THE
FLOW THROUGH THE LOWEST 6 KM IS RATHER WEAK...BUT HIGH PWAT VALUES
AND STRONG LOW-LEVEL LAPSE RATES MAY CONTRIBUTE TO ISOLD DAMAGING
WET MICROBURSTS/HAIL WITH STRONG MULTICELL STORMS.
..MIDWEST...
ISOLD TSTMS MAY FORM ALONG/AHEAD OF A WEAK UPPER TROUGH AXIS DURING
PEAK HEATING THIS AFTN. SUBSIDENCE IN WAKE OF THE STRONGER LEAD
DISTURBANCE EXITING INTO THE MID-ATLANTIC REGION WILL LIKELY BE
DETRIMENTAL TO AN OTHERWISE FAVORABLE SET-UP FOR MORE WIDESPREAD AND
STRONGER ACTIVITY. HOWEVER...IF AN UPDRAFT CAN MANAGE TO BECOME
SUSTAINED...UNIDIRECTIONAL WNWLY FLOW REGIME AND DRY SUB-CLOUD LAYER
MAY AUGMENT CONVECTIVE WIND GUSTS. COOLER MID-TROPOSPHERIC
TEMPERATURES MAY ALSO BE FAVORABLE FOR SMALL HAIL.
..COASTAL SERN FL...
ISOLD NON-SVR TSTMS MAY FORM ALONG THE ECOAST SEABREEZE LATER THIS
AFTN OWING TO STRONG LOW-LEVEL HEATING. ACTIVITY WILL DIMINISH THIS
EVE.
..NRN ROCKIES...
CONVECTION WAS FORMING ALONG THE HIGHER TERRAIN OF ID/SWRN MT ALONG
NRN PERIPHERY OF THE WRN STATES UPER RIDGE. ISOLD TSTMS WILL BE
POSSIBLE THROUGH THE EVENING...LIKELY SPREADING INTO PARTS OF ECNTRL
MT OVERNIGHT.
.RACY.. 04/28/2007
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