SWODY2
SPC AC 021659
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1159 AM CDT THU JUL 02 2009
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE HIGH
PLAINS...CNTRL PLAINS AND MID-MO VALLEY...
...HIGH PLAINS/CNTRL PLAINS/MID-MO VALLEY...
A BROAD UPPER-LEVEL RIDGE WILL CONTINUE ACROSS MUCH OF THE NRN
STATES FRIDAY AS SEVERAL SUBTLE UPPER-LEVEL DISTURBANCES MOVE EWD
ACROSS THE REGION. AT THE SFC...A QUASI-STATIONARY FRONT IS FORECAST
ACROSS ERN MT SEWD INTO SWRN SD WITH AN AXIS OF INSTABILITY IN PLACE
FROM ERN CO NNWWD THROUGH ERN WY INTO CNTRL AND ERN MT. SCATTERED
THUNDERSTORMS SHOULD INITIATE ALONG THIS AXIS OF INSTABILITY AND
MOVE SEWD ACROSS THE SLIGHT RISK AREA DURING THE LATE AFTERNOON AND
EARLY EVENING. FORECAST SOUNDINGS ALONG THIS CORRIDOR AT 00Z SHOW
MOSTLY MODERATE VERTICAL SHEAR PROFILES DUE TO DIRECTIONAL TURNING
WITH STEEP MID-LEVEL LAPSE RATES SUGGESTING SUPERCELLS WITH HAIL
POTENTIAL WILL EXIST. THE BEST CHANCE FOR A PERSISTENT ORGANIZED
STORM COMPLEX SHOULD BE OVER ERN MT WHERE A SHORTWAVE TROUGH IS
FORECAST BY THE NAM/GFS MODELS AND VERTICAL SHEAR SHOULD BE A BIT
STRONGER PARTIALLY DUE TO A LOW-LEVEL JET FEATURE. IN ADDITION TO
HAIL...WIND DAMAGE WILL BE POSSIBLE ESPECIALLY IF A STORM CLUSTER
CAN PERSIST INTO THE EVENING.
FURTHER SOUTHEAST...ELEVATED THUNDERSTORMS SHOULD BE ONGOING ALONG
THE STATIONARY FRONTAL BOUNDARY FRIDAY MORNING IN SRN SD AND NERN
NEB. SOUTH OF THE FRONTAL BOUNDARY...MODERATE TO STRONG INSTABILITY
IS FORECAST BY MIDDAY WHERE MODEL FORECASTS DEVELOP SCATTERED
SFC-BASED THUNDERSTORMS DURING THE AFTERNOON. AN INCREASE IN
CONVECTIVE COVERAGE SHOULD OCCUR DURING THE LATE AFTERNOON WITH THE
POSSIBILITY OF AN MCS DEVELOPING ON THE NOSE OF THE LOW-LEVEL JET IN
THE EVENING. FORECAST SOUNDINGS ALONG THIS CORRIDOR AT 00Z SHOW
MODERATE TO STRONG VERTICAL SHEAR PROFILES PARTIALLY DUE TO A
MID-LEVEL JET PASSING THROUGH THE RIDGE. THIS COMBINED WITH MODERATE
TO STRONG INSTABILITY AND STEEP MID-LEVEL LAPSE RATES WILL LIKELY BE
SUFFICIENT FOR ISOLATED SUPERCELLS WITH A PERSISTENT HAIL THREAT
INTO THE EVENING. BOWING LINE-SEGMENTS WILL BE JUST AS LIKELY
ESPECIALLY IF AN MCS CAN ORGANIZE WITH THE INCREASING LOW-LEVEL JET.
THIS MAY INCREASE THE WIND DAMAGE POTENTIAL WITH TIME FRIDAY
EVENING.
...NEW ENGLAND/ERN NY...
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS THE NERN STATES
FRIDAY WITH A WELL-DEVELOPED SFC TROUGH IN PLACE ACROSS WRN PARTS OF
NEW ENGLAND. THUNDERSTORMS SHOULD DEVELOP ALONG THIS SFC TROUGH BY
MIDDAY WITH THE STORMS MOVING EWD ACROSS NEW ENGLAND DURING THE MID
TO LATE AFTERNOON. FORECAST SOUNDINGS AT 21Z ALONG THE SFC TROUGH
SHOW MUCAPE VALUES APPROACHING 1000 J/KG WITH STEEP LOW-LEVEL LAPSE
RATES. IN SPITE OF THE WEAK VERTICAL SHEAR...THIS THERMODYNAMIC
PROFILE MAY SUPPORT A FEW DAMAGING WIND GUSTS NEAR PEAK HEATING.
...FLORIDA...
A QUASI-STATIONARY FRONTAL BOUNDARY WILL BE IN PLACE FRIDAY ACROSS
SRN GA. SOUTH OF THIS BOUNDARY...MODERATE TO STRONG INSTABILITY
SHOULD DEVELOP FRIDAY AFTERNOON WITH SCATTERED THUNDERSTORMS
INITIATING ON SEA BREEZE BOUNDARIES AND ACROSS THE FL PENINSULA.
ALTHOUGH VERTICAL SHEAR PROFILES ACROSS FORECAST TO BE QUITE
WEEK...STEEP LOW-LEVEL LAPSE RATES COMBINED WITH A VERY MOIST
BOUNDARY LAYER MAY BE SUFFICIENT FOR A FEW DAMAGING WIND GUSTS WITH
THE STRONGER CELLS.
..BROYLES.. 07/02/2009
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