DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 110445
SWODY1
SPC AC 110443

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1143 PM CDT MON OCT 10 2011

VALID 111200Z - 121200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A STRONG UPPER JET NOSING INTO THE PACIFIC NW WILL OVERSPREAD THE
INTERIOR NW INTO THE CNTRL STATES AS AN UPPER RIDGE AMPLIFIES OVER
THE WRN ATLANTIC. THIS PATTERN WILL CONTRIBUTE TO A LARGER SCALE
UPPER TROUGH WITH EMBEDDED SMALLER SCALE DISTURBANCES MOVING INTO
THE CNTRL PLAINS AND A WEAKENING SHORTWAVE TROUGH OVER THE SERN U.S.
IN THE LOW LEVELS...AN ANTICYCLONE/S INFLUENCE WILL BE SLOW TO ABATE
ACROSS THE MS VALLEY INTO THE LOW PLAINS AHEAD OF A LEE TROUGH.
FARTHER E...DECAYING HYBRID SUBTROPICAL LOW WILL CONTINUE TO EVOLVE
INTO AN EXTRA TROPICAL SYSTEM AND MOVE OFF THE SERN COAST BY LATE
EVENING.

....CNTRL-SRN PLAINS...
STRENGTHENING COMPONENT OF MID-UPPER FLOW FROM THE ROCKIES EWD INTO
THE CNTRL STATES WILL ALLOW AN ELEVATED MIXED LAYER TO OVERSPREAD
THE REGION DURING THE DAY. WEAK LOW LEVEL MOISTURE RETURN IN WAKE
OF A DECAYING FRONT LOCATED OVER THE MS RIVER VALLEY WILL LIMIT THE
DEGREE OF DESTABILIZATION DESPITE THE PRESENCE OF STEEPENING
TROPOSPHERIC LAPSE RATES/STRONG SURFACE HEATING DURING THE
AFTERNOON. CONVERGENCE ALONG THE LEE TROUGH AND UPPER FORCING FOR
ASCENT /DCVA/ ASSOCIATED WITH AN EJECTING ELONGATED SHORTWAVE
TROUGH...WILL SUFFICIENTLY WEAKEN THE CAP DURING THE
AFTERNOON--LEADING TO ISOLATED TO WIDELY SCATTERED STORMS. FORECAST
SOUNDINGS SHOW SBCAPE AOB 500 J/KG FROM KS NWD PERHAPS SUPPORTING A
LOW WIND/HAIL RISK. FARTHER S...RECENT MODEL GUIDANCE SHOWS
SLIGHTLY GREATER POTENTIAL INSTABILITY DEVELOPING WITH SBCAPE
APPROACHING 1000 J/KG DURING PEAK HEATING NEAR THE TX CAPROCK WITH A
DEEPLY VEERING WIND PROFILE WITH POSSIBLE WEAK SUPERCELLS AND AN
ATTENDANT ISOLATED LARGE HAIL/SEVERE WIND THREAT.

...COASTAL CAROLINAS/SERN VA...
AS A POLEWARD MOVING UPPER JET OFF THE SERN COAST MOVES NWD INTO THE
MID-ATLANTIC STATES DURING THE DAY...AN ELY 40+ KT LLJ WILL SHIFT
NWD FROM THE CAROLINAS INTO THE TIDEWATER VICINITY OVERNIGHT. AN
EFFECTIVE BAROCLINIC ZONE NEAR THE COAST AND ADJACENT SHELF WATERS
WILL TEND TO CONFINE GREATER LOW LEVEL THETA-E OVER THE GULF STREAM
AND IMMEDIATE COASTAL VICINITY. ON THE SRN PERIPHERY OF THE
STRONGER LOW LEVEL SHEAR...FORECAST SOUNDINGS INDICATE WEAK BUOYANCY
WITHIN A MOIST AIRMASS /PW NEAR 2 INCHES/...WHICH MAY FOSTER A FEW
SHALLOW WEAKLY ROTATING UPDRAFTS AND A BRIEF/WEAK TORNADO TO
DEVELOP.

..SMITH/GUYER.. 10/11/2011

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