DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 290900
SWOD48
SPC AC 290859

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0359 AM CDT MON JUL 29 2013

VALID 011200Z - 061200Z

...DISCUSSION...
MEDIUM RANGE MODELS INDICATE SEASONABLY STRONG NORTHWEST MID/UPPER
FLOW WILL PREVAIL LATE THIS WEEK THROUGH THE WEEKEND...WITHIN A
CONFLUENT REGIME BETWEEN SUBTROPICAL RIDGING...CENTERED OVER THE
SOUTHERN ROCKIES...AND UPPER TROUGHING...CENTERED OVER THE EASTERN
CANADIAN PROVINCES. ON THE SOUTHERN FRINGE OF THIS STRONGER
FLOW...A PLUME OF VERY WARM DEEPLY MIXED AIR EMERGING FROM THE
PLATEAU REGION SHOULD BEGIN ADVECTING EAST OF THE HIGHER TERRAIN
...ABOVE A MOIST/MOISTENING BOUNDARY LAYER...ALONG A
QUASI-STATIONARY FRONTAL ZONE ACROSS THE NORTH CENTRAL PLAINS INTO
MIDDLE MISSISSIPPI/LOWER OHIO VALLEYS AND SOUTHERN MID ATLANTIC
COAST REGION.

THE FRONTAL ZONE MAY BECOME THE PRIMARY FOCUS FOR VIGOROUS
THUNDERSTORM DEVELOPMENT THROUGH THE PERIOD. HOWEVER...DUE TO
AMPLIFIED NATURE OF THE FLOW...STEEP MID-LEVEL LAPSE RATES
ASSOCIATED WITH THE ELEVATED MIXED LAYER AIR MAY NOT SPREAD EAST OF
THE MIDDLE MISSISSIPPI VALLEY. AND THE LOWER CENTRAL PLAINS INTO
THE MIDDLE MISSISSIPPI VALLEY MAY BE IN QUESTION BY THE
WEEKEND...DUE TO REPEAT CONVECTIVE DEVELOPMENT ASSOCIATED WITH SHORT
WAVE IMPULSES MIGRATING AROUND THE PERIPHERY OF THE SUBTROPICAL
RIDGE. ANY ONE OF A NUMBER OF THESE SUBTLE PERTURBATIONS...WHICH
MAY BE EMBEDDED WITHIN THE LARGER SCALE FLOW...COULD CONTRIBUTE TO
THE EVOLUTION OF ORGANIZED CONVECTIVE SYSTEMS CAPABLE OF PRODUCING
SWATHS OF DAMAGING WIND GUSTS...AS THEY PROGRESS EAST OF THE
ROCKIES...THROUGH THE WEST NORTHWESTERLY FLOW REGIME. HOWEVER...THE
PREDICTABILITY OF THESE FEATURES IS VERY LOW...AND TOO MUCH
UNCERTAINTY STILL EXISTS TO CONFIDENTLY ASCERTAIN AND DELINEATE ANY
POTENTIAL REGIONAL SEVERE RISK AREAS.

..KERR.. 07/29/2013

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