SWODY3
SPC AC 090816
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0216 AM CST SAT FEB 09 2008
VALID 111200Z - 121200Z
..THERE IS A SLGT RISK OF SVR TSTMS LATE MON/MONDAY NIGHT ACROSS
PARTS OF THE SOUTH CENTRAL PLAINS....
..SYNOPSIS...
AMPLIFICATION WITHIN THE POLAR STREAM ACROSS THE NORTHERN/EASTERN
PACIFIC INTO THE INTERMOUNTAIN WEST/ROCKIES LATE THIS WEEKEND IS
EXPECTED TO CONTINUE AN EASTWARD TRANSLATION THROUGH THIS FORECAST
PERIOD. WITHIN THIS REGIME...A SIGNIFICANT SHORT WAVE IMPULSE IS
PROGGED TO CONTINUE DIGGING TO THE LEE OF THE NORTHERN ROCKIES...AS
AN UPSTREAM RIDGE PROGRESSES INLAND ACROSS THE PACIFIC COAST...AHEAD
OF A SERIES OF STRONG IMPULSES EMANATING FROM AN INTENSE ZONAL
UPSTREAM JET. AT THE SAME TIME...MODELS SUGGEST THAT FLOW WILL
STRENGTHEN WITHIN A BELT EXTENDING OUT OF THE SUBTROPICAL PACIFIC
THROUGH THE MEXICAN PLATEAU...WITH AN INITIAL EMBEDDED BROAD SHORT
WAVE IMPULSE PROGRESSING EASTWARD INTO THE WESTERN GULF OF MEXICO.
LARGE SPREAD PERSISTS AMONG THE MODELS CONCERNING THE EVOLUTION OF
THE DIGGING SHORT WAVE TO THE LEE OF THE ROCKIES. BUT...THE BULK OF
GUIDANCE APPEARS TO SUGGEST THAT AN INCREASINGLY DIVERGENT UPPER
FLOW FIELD...ASSOCIATED WITH THE INTERACTING STREAMS OF FLOW ...WILL
BECOME FOCUSED ACROSS THE SOUTH CENTRAL PLAINS SOMETIME LATE MONDAY
OR MONDAY NIGHT. AND...WITH A CONDITIONALLY/ CONVECTIVELY UNSTABLE
ENVIRONMENT EXPECTED TO BE IN PLACE ACROSS THIS REGION BY THAT
TIME...THIS FORCING IS EXPECTED TO CONTRIBUTE TO A SUBSTANTIAL
INCREASE IN THUNDERSTORM ACTIVITY...SOME OF WHICH COULD BECOME
SEVERE.
..SOUTH CENTRAL STATES...
CONTINUED LOW-LEVEL MOISTENING ON SOUTHERLY RETURN FLOW ACROSS THE
LOWER RIO GRANDE VALLEY THROUGH THE SOUTHERN PLAINS/OZARK PLATEAU
REGION IS EXPECTED MONDAY. THIS APPEARS LIKELY TO OCCUR BENEATH A
CAPPING ELEVATED MIXED LAYER...WHICH MODELS SUGGEST WILL CONTRIBUTE
TO MOST UNSTABLE CAPE ON THE ORDER OF 1000 J/KG...NEAR A STALLED
FRONTAL ZONE EXTENDING ACROSS THE SOUTH CENTRAL PLAINS AND OZARKS.
WHILE THE TIMING OF STRONG MID/UPPER FORCING IS STILL UNCLEAR /ONSET
CURRENTLY SEEMS MOST PROBABLE EARLY MONDAY EVENING/...IT SHOULD BE
SUFFICIENT TO WEAKEN CAP...LIKELY SUPPORTING THE INITIATION OF
STORMS EAST OF A DRY LINE/FRONTAL INTERSECTION ACROSS
CENTRAL/NORTHERN OKLAHOMA. WITHIN THE PRESENCE OF STRONG DEEP LAYER
SHEAR AND SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS...A FEW
SUPERCELLS APPEAR POSSIBLE...BEFORE CONVECTION EXPANDS IN
COVERAGE...DEVELOPING EAST NORTHEASTWARD THROUGH THE OZARK
PLATEAU...AND SOUTHWARD THROUGH THE RED RIVER VALLEY.
GIVEN THE SHARPNESS OF THE FRONT...AND THE ANTICIPATED WEAKNESS OF
THE SURFACE FRONTAL WAVE DEVELOPMENT...IT APPEARS THAT STORMS WILL
TEND TO EITHER FORM ABOVE THE FRONTAL INVERSION...OR QUICKLY BECOME
UNDERCUT BY THE FRONT...WHICH IS EXPECTED TO BEGIN ADVANCING
SOUTHWARD MONDAY EVENING. THIS MAY MITIGATE ANY TORNADO/DAMAGING
WIND POTENTIAL. BUT...AT LEAST THE RISK FOR HAIL WILL EXIST...SOME
OF WHICH COULD BECOME FAIRLY LARGE BEFORE STORMS WEAKEN LATER MONDAY
NIGHT.
.KERR.. 02/09/2008
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