Thursday, October 4, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 050057
SWODY1
SPC AC 050054

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 PM CDT THU OCT 04 2007

VALID 050100Z - 051200Z

..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS N-CENTRAL KS TO SWRN
MN....

..SYNOPSIS...
IN MID/UPPER LEVELS...PRIMARY FEATURE FOR REMAINDER PERIOD WILL BE
AMPLIFYING TROUGH OVER PACIFIC COAST STATES...WHILE RIDGING
PREDOMINATED FROM MID-ATLANTIC REGION SWWD TO N-CENTRAL MEX.
FARTHER S..ELONGATED UPPER LEVEL CYCLONIC SHEAR ZONE WILL PERSIST
OVER NWRN THROUGH SWRN GULF. ASSOCIATED LOW LEVEL CIRCULATION --
NEAR 27.5N91.5W AS OF 04/23Z...SHOULD CONTINUE DRIFTING WWD TO WNWWD
ACROSS OPEN GULF WATERS. SEVERAL MID/UPPER LEVEL SHORTWAVE
PERTURBATIONS ARE EMBEDDED WITHIN SWLY FLOW BELT AHEAD OF PACIFIC
COAST TROUGH. ONE IS EVIDENT IN MOISTURE CHANNEL IMAGERY OVER WRN
KS...ANOTHER LIFTING NEWD FROM NERN AZ/SERN UT INTO SWRN CO...AND
ANOTHER OVER SWRN/S-CENTRAL AZ.

AT SFC...WAVE FRONTAL ZONE IS ANALYZED FROM SERN WY ESEWD ACROSS SRN
NEB PANHANDLE...THEN NEWD OVER N-CENTRAL NEB...SERN
SD...SWRN/S-CENTRAL MN. WRN PORTION OF THIS FRONT SHOULD LIFT NWD
ACROSS NWRN NEB AND ERN WY OVERNIGHT...IN RESPONSE TO CONTINUED LEE
TROUGHING AND EARLY-STAGE CYCLOGENESIS OVER WY. FARTHER E...FRONT
SHOULD DRIFT N MORE SLOWLY...ACROSS SERN SD AND SRN MN.

..CENTRAL/NRN PLAINS...
SCATTERED TSTMS HAVE DEVELOPED OVER N-CENTRAL KS AND PORTIONS
S-CENTRAL/SERN NEB. DAMAGING GUSTS AND ISOLATED...MOSTLY MRGLLY SVR
HAIL...ARE POSSIBLE. TORNADO THREAT CANNOT BE RULED OUT...BUT
APPEARS STRONGLY TIED TO STORM-SCALE AND BOUNDARY PROCESSES GIVEN
LACK OF MORE ROBUST EFFECTIVE BULK SHEAR. BECAUSE OF S OF WARM
FRONT...DIFFERENTIAL HEATING BOUNDARY REMAINS ALONG SRN RIM OF
FORMER CLOUD COVER AREA FROM MORNING/EARLY AFTERNOON. THIS BOUNDARY
EXTENDS FROM NWRN IA SWWD ACROSS MO RIVER JUST N OMA...TO ABOUT 30
SE HSI...TO KS/NEB BORDER NE HLC. THIS INTERSECTS ANOTHER SUCH
BOUNDARY THAT EXTENDS SWWD BETWEEN HYS-HLC..BECOMING DIFFUSE ACROSS
W-CENTRAL KS. FLOW N OF DIFFERENTIAL HEATING BOUNDARIES REMAINS
BACKED...WITH RELATIVELY STABLE BOUNDARY LAYER CONTINUING. ENLARGED
LOW LEVEL HODOGRAPHS WILL CONTINUE ALONG AND N OF
BOUNDARIES...CONTINUING 0-1 KM SRH 200-300 J/KG NOW SHOWN IN
VWP/PROFILER DATA. WEAKNESSES IN MIDLEVEL WINDS WILL LIMIT
DEEP-LAYER SHEAR. PRIND SVR POTENTIAL WITH ONGOING ACTIVITY MAY BE
MAXIMIZED AS CONVECTION INTERACTS WITH BOUNDARY DURING REMAINDER
EVENING.

TRENDS WILL BE TOWARD PROGRESSIVELY MORE ELEVATED INFLOW-LAYER
PARCELS WITH TIME TONIGHT...AS AIR MASS SLOWLY COOLS IN MOIST SECTOR
E OF DRYLINE AND SE OF OUTFLOW BOUNDARY. CAPPING NOTED IN OAX RAOB
MAY LIMIT EWD EXTENT OF DEVELOPMENT. CONVECTIVE COVERAGE SHOULD
INCREASE AND SPREAD/EXPAND NNEWD TOWARD SRN MN...WITH WIND POTENTIAL
SLOWLY DIMINISHING AND OCCASIONAL HAIL STILL POSSIBLE.

..SWRN CONUS...
WIDELY SCATTERED TSTMS HAVE DEVELOPED ATOP DIURNALLY HEATED PLUME OF
40S/50S F SFC DEW POINTS OVER PORTIONS CENTRAL/SRN/ERN AZ AND WRN
NM. NEARLY UNIDIRECTIONAL DEEP-LAYER WIND PROFILES ARE
EXPECTED...WITH FAST-MOVING CELLS CAPABLE OF PRODUCING STG/ISOLATED
SVR GUSTS AND HAIL. THIS ACTIVITY SHOULD PERSIST AND BE SFC-BASED
FOR ANOTHER 2-3 HOURS UNTIL SFC COOLING REMOVES BOUNDARY LAYER CAPE.


...SRN PLAINS...
CLUSTERS OF OUTFLOW-DOMINANT MULTICELLULAR CONVECTION CONTINUE OVER
PORTIONS PERMIAN BASIN/W-CENTRAL TX...NE MAF...AS WELL AS SW FST
INTO BIG BEND REGION. DEEP-LAYER SHEAR PROFILES WILL REMAIN WEAK.
PRIND SVR POTENTIAL WITH THIS ACTIVITY -- ALREADY MRGL -- WILL
DIMINISH FURTHER THROUGH REMAINDER EVENING AS AIR MASS STABILIZES
FROM COMBINATION OF DIABATIC COOLING AND OUTFLOW PROCESSES.
STRONGER CELLS STILL MAY PRODUCE GUSTS/HAIL APCHG SVR LEVELS.

.EDWARDS.. 10/05/2007

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