DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161631
SWODY1
SPC AC 161629

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT FRI AUG 16 2013

VALID 161630Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
ALTHOUGH THE CREST OF THE RIDGE EXTENDING TO THE NORTH OF A SOUTHERN
PLATEAU SUBTROPICAL HIGH CENTER MAY FLATTEN SOME LATER
TODAY/TONIGHT...MID/UPPER FLOW ACROSS MUCH OF THE U.S. APPEARS
LIKELY TO REMAIN AMPLIFIED...BUT WEAK TO MODEST IN
STRENGTH...THROUGH THIS FORECAST PERIOD. WITHIN THIS REGIME...A
PROMINENT SHORT WAVE IMPULSE...DIGGING INTO BASE OF LARGER SCALE
EASTERN U.S. UPPER TROUGHING...MAY CONTRIBUTE TO THE EVOLUTION OF A
WEAK DEEP LAYER LOW EAST OF THE LOWER MISSISSIPPI VALLEY BY 12Z
SATURDAY. AT THE SAME TIME...WITHIN A BELT OF LESS AMPLIFIED FLOW
TO THE NORTH...ONE SHORT WAVE TROUGH IS FORECAST TO PROGRESS
NORTHEAST OF THE CANADIAN ROCKIES...WHILE ANOTHER GRADUALLY TURNS
EASTWARD ACROSS QUEBEC THROUGH NORTHERN NEW ENGLAND AND THE CANADIAN
MARITIMES.

IN ASSOCIATION WITH THE UPPER DEVELOPMENTS...SIGNIFICANT LOW-LEVEL
COOLING AND DRYING HAS OCCURRED ACROSS MUCH OF THE CENTRAL AND
EASTERN U.S...IN THE WAKE OF A SURFACE FRONTAL ZONE NOW CURVING
ACROSS SOUTH ATLANTIC AND GULF COASTAL AREAS. HIGHER MOISTURE
CONTENT AIR /CHARACTERIZED BY 70F+ SURFACE DEW POINTS AND
PRECIPITABLE WATER ON THE ORDER OF 2 INCHES OR SO/ IS GENERALLY
CONFINED TO SOUTHERN GEORGIA AND FLORIDA AND THE TEXAS COASTAL
PLAIN. BUT AT LEAST MODEST MOISTURE LINGERS WITHIN AN
EASTERLY/SOUTHEASTERLY UPSLOPE LOW-LEVEL FLOW REGIME ACROSS THE HIGH
PLAINS...WHERE MID-LEVEL LAPSE RATES ASSOCIATED WITH VERY WARM AND
DEEPLY MIXED AIR EMERGING FROM THE PLATEAU REGION REMAIN QUITE
STEEP.

...SOUTHEAST...
IN THE WAKE OF AN INITIAL BROAD AREA OF CONVECTION NOW SPREADING
NORTHEASTWARD THROUGH THE CAROLINAS...INCREASINGLY DIVERGENT UPPER
FLOW ALREADY APPEARS TO BE CONTRIBUTING TO INCREASING CONVECTIVE
DEVELOPMENT ACROSS THE NORTHEASTERN GULF OF MEXICO INTO NORTHERN
FLORIDA. A WINDOW OF OPPORTUNITY STILL APPEARS TO EXIST INTO THE
AFTERNOON HOURS FOR DEVELOPMENT AND INTENSIFICATION ALONG THE FRONT
ACROSS SOUTHERN GEORGIA INTO EXTREME SOUTHERN SOUTH CAROLINA...WHERE
BOUNDARY LAYER CAPE IS BECOMING MODERATELY LARGE. IF THIS
OCCURS...THERE APPEARS AT LEAST LOW PROBABILITIES FOR SEVERE WIND
GUSTS...AIDED BY HEAVY PRECIPITATION LOADING.

...CENTRAL AND SOUTHERN PLAINS...
MID/UPPER SUPPORT FOR CONVECTIVE DEVELOPMENT REMAINS UNCLEAR...BUT
THE ENVIRONMENT LIKELY WILL BECOME SUPPORTIVE OF AT LEAST THE
POTENTIAL FOR SUPERCELLS LATE THIS AFTERNOON AND EVENING. BENEATH
STEEP MID-LEVEL LAPSE RATES...DAYTIME HEATING IS EXPECTED TO YIELD
CAPE OF 1000-2000 J/KG ACROSS THE TEXAS PANHANDLE INTO EASTERN
COLORADO...AND ADJACENT AREAS OF THE HIGH PLAINS...WHERE 30+ KT
NORTHERLY 500 MB FLOW WILL CONTRIBUTE TO MODERATELY STRONG SHEAR.

...OREGON...
MODESTLY STRONG SOUTHWESTERLY MID/UPPER FLOW MAY CONTRIBUTE TO
SUFFICIENT DEEP LAYER SHEAR TO ENHANCE ANY THUNDERSTORM ACTIVITY TO
THE EAST OF THE CASCADES LATE THIS AFTERNOON AND EVENING. ONE OR
TWO STORMS EXHIBITING SUPERCELL CHARACTERISTICS MAY NOT BE OUT OF
THE QUESTION...THOUGH THERMODYNAMIC PROFILES APPEAR ONLY MARGINALLY
SUPPORTIVE OF SEVERE WIND/HAIL.

..KERR/COHEN.. 08/16/2013

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