SWODY1
SPC AC 230559
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1259 AM CDT MON JUL 23 2007
VALID 231200Z - 241200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MID MO
VALLEY/CENTRAL PLAINS AND VICINITY...
..SYNOPSIS...
A LARGE UPPER RIDGE IS FORECAST TO PREVAIL ACROSS THE WRN AND INTO
THE CENTRAL CONUS THIS PERIOD -- CENTERED OVER THE NRN HIGH PLAINS
BY 24/00Z. NORTHERN PORTIONS OF THIS RIDGE SHOULD DRIFT EWD WITH
TIME...AS AN UPSTREAM TROUGH IS EXPECTED TO REACH THE PAC NW DURING
THE SECOND HALF OF THE PERIOD.
MEANWHILE...A TROUGH IS FORECAST TO PERSIST OVER THE ERN
CONUS...WITH EMBEDDED CLOSED LOW FORECAST TO RETROGRADE WWD FROM THE
MID-ATLANTIC REGION INTO THE MID/UPPER OH VALLEY.
THE SURFACE PATTERN OVER THE CONUS SHOULD REMAIN GENERALLY WEAK
THROUGH THE PERIOD E OF THE ROCKIES...WHILE A COLD FRONT IS FORECAST
TO MOVE ACROSS PARTS OF THE NWRN CONUS AHEAD OF THE APPROACHING
UPPER TROUGH.
..MID MO VALLEY SWWD TO THE TX PANHANDLE/WRN OK...
STORMS SHOULD BE MOVING ACROSS THE MID MO VALLEY REGION AT THE START
OF THE PERIOD...IN CONJUNCTION WITH A WEAK/SWWD-MOVING UPPER WAVE.
SOME SEVERE THREAT MAY BE ONGOING AT THE START OF THE PERIOD WITH
THESE STORMS...WITH THE THREAT FORECAST TO INCREASE INTO THE
AFTERNOON AS MOIST BOUNDARY LAYER OVER THE PLAINS
HEATS/DESTABILIZES.
THOUGH FLOW IS FORECAST TO BE NELY IN THE MIDDLE AND UPPER
TROPOSPHERE BETWEEN UPPER HIGH TO THE NW AND UPPER LOW TO
ESE...MODERATE FLOW MAGNITUDE AND STRONG VEERING WITH HEIGHT
SUGGESTS AMPLE SHEAR FOR ORGANIZED/ROTATING STORMS.
ATTM...IT APPEARS THAT THE SWWD-MOVING CLUSTER OF STORMS INITIALLY
OVER THE MO VALLEY REGION SHOULD CROSS NRN MO/SERN NEB THROUGH EARLY
AFTERNOON...AND THEN MOVE INTO S CENTRAL NEB/CENTRAL KS DURING THE
AFTERNOON. WITH THIS CONVECTION POSSIBLY ORGANIZING INTO AN MCS
ALONG A LEADING COLD POOL...THREAT FOR DAMAGING WINDS IS EXPECTED
ALONG WITH HAIL.
FURTHER S ACROSS KS AND INTO PARTS OF WRN OK...OTHER/MORE ISOLATED
STORMS ARE EXPECTED TO DEVELOP. WHILE SHEAR WILL BE SOMEWHAT WEAKER
ACROSS THIS REGION...MODERATE INSTABILITY SHOULD COMPENSATE --
LIKELY YIELDING A THREAT FOR HAIL AND PERHAPS LOCALLY-GUSTY WINDS.
AS LOW-LEVEL JET DEVELOPS FROM THE S ACROSS THE CENTRAL AND SRN HIGH
PLAINS...STORMS MAY PERSIST IN ONE OR MORE CLUSTERS INTO THE
OVERNIGHT HOURS...ALONG WITH A LIMITED SEVERE THREAT -- PERHAPS AS
FAR W AS WRN KS AND AS FAR S AS THE TX SOUTH PLAINS.
..PORTIONS OF WRN AND CENTRAL MT AND ADJACENT AREAS OF ID...
WEAK SHORT-WAVE DISTURBANCES MOVING NEWD ACROSS ID/WRN AND CENTRAL
MT -- ON WRN FRINGE OF UPPER RIDGE -- SHOULD CONTRIBUTE TO AFTERNOON
CONVECTIVE DEVELOPMENT ACROSS THIS REGION. HOWEVER...WITH STRONGER
FLOW ALOFT FORECAST TO REMAIN W/NW OF THIS REGION...DEEP-LAYER SHEAR
SHOULD REMAIN MARGINAL. THIS COMBINED WITH LIMITED CAPE /GENERALLY
AROUND 500 J/KG MIXED-LAYER CAPE/ SUGGESTS A FAIRLY ISOLATED SEVERE
THREAT -- MAINLY IN THE FORM OF LOCALLY GUSTY/DAMAGING WINDS.
..CENTRAL AND SRN FL...
MOIST BOUNDARY LAYER BUT FAIRLY WEAK LAPSE RATES SHOULD YIELD ONLY
MARGINAL INSTABILITY /GENERALLY LESS THAN 1000 J/KG MIXED-LAYER
CAPE/ THROUGH THE AFTERNOON. HOWEVER...SLIGHTLY-ENHANCED FLOW ALOFT
ACROSS THIS REGION -- AROUND SRN PERIPHERY OF ERN U.S. UPPER LOW --
MAY AID IN THE DEVELOPMENT OF A FEW STRONGER/SUSTAINED UPDRAFTS.
THUS...WILL MAINTAIN 5% SEVERE PROBABILITIES OVER THE SRN 2/3 OF THE
FL PENINSULA THIS FORECAST.
.GOSS/GUYER.. 07/23/2007
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