Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 070454
SWODY2
SPC AC 070453

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1153 PM CDT MON JUL 06 2015

VALID 081200Z - 091200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
THE RISK FOR SEVERE THUNDERSTORMS ACROSS THE U.S. WEDNESDAY THROUGH
WEDNESDAY NIGHT CURRENTLY APPEARS NEGLIGIBLE.

...SYNOPSIS...
LATEST MODEL OUTPUT OFFERS LITTLE CHANGES FROM PRIOR RUNS.
SEASONABLY HIGH MOISTURE CONTENT AIR WILL REMAIN CONFINED TO AREAS
ALONG AND SOUTH OF A SURFACE FRONTAL ZONE WHICH HAS ALREADY ADVANCED
TO THE SOUTHEAST AND SOUTH OF THE STRONGER MID-LATITUDE
WESTERLIES...WHICH LIKELY WILL REMAIN NEAR AND NORTH OF THE
CANADIAN/U.S. BORDER THROUGH THIS FORECAST PERIOD.  WHILE THE FRONT
MAY PROGRESS ACROSS AND EAST OF THE NORTH ATLANTIC COAST DURING THE
DAY WEDNESDAY...IT IS EXPECTED TO REMAIN QUASI-STATIONARY ACROSS THE
OHIO VALLEY INTO THE CENTRAL PLAINS.

MODEST SUBTROPICAL RIDGING AT MID-LEVELS IS STILL FORECAST TO EXPAND
WESTWARD ACROSS THE GULF COAST REGION...WITH FLOW TRANSITIONING TO
BROADLY ANTICYCLONIC ON ITS WESTERN AND NORTHERN PERIPHERY...FROM
THE PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS THROUGH THE OHIO
VALLEY AND NORTHERN/MID ATLANTIC COAST.  HOWEVER...AT LEAST ONE
CONVECTIVELY GENERATED OR ENHANCED PERTURBATION EMERGING FROM THE
SOUTH CENTRAL PLAINS APPEARS LIKELY TO BE EMBEDDED WITHIN THIS
REGIME...AND COULD REMAIN FAIRLY WELL-DEFINED WHILE CROSSING THE
MIDDLE MISSISSIPPI VALLEY...BEFORE BECOMING INCREASINGLY SHEARED TO
THE EAST NORTHEAST.  A MORE SUBTLE IMPULSE MAY CROSS THE CENTRAL
APPALACHIANS/MID ATLANTIC COAST REGION...WHILE ANOTHER PERTURBATION
EMERGES FROM THE INTERMOUNTAIN WEST AND CROSSES THE CENTRAL ROCKIES.


AT THE SAME TIME...A CLOSED LOW...WHICH APPEARS TO BE ASSOCIATED
WITH PHASING OF A WEAK SOUTHERN BRANCH OF SPLIT MID-LATITUDE
WESTERLIES...AND THE SUBTROPICAL STREAM...IS FORECAST TO CONTINUE
VERY GRADUALLY PROGRESSING INLAND ACROSS THE CALIFORNIA COAST.

...MIDDLE MISSISSIPPI VALLEY AREA...
ALTHOUGH WIND FIELDS WITH THE CONVECTIVELY GENERATED OR ENHANCED
IMPULSE EMERGING FROM THE PLAINS MAY REMAIN STRONG AND SHEARED
ENOUGH TO PROVIDE AT LEAST SOME SUPPORT FOR SEVERE WEATHER POTENTIAL
WEDNESDAY...THERE APPEARS INCREASING UNCERTAINTY CONCERNING ITS
TRACK RELATIVE TO THE LINGERING SURFACE FRONT ACROSS THE REGION.  IT
MAY REMAIN MOSTLY TO THE COOL SIDE OF THE BOUNDARY...WHICH MAY BE
REINFORCED BY CONSIDERABLE RESIDUAL EARLY PERIOD CONVECTIVE
PRECIPITATION...AND SLOW TO RETREAT NORTHWARD.  AT THE PRESENT
TIME...TOO MANY UNCERTAINTIES EXIST TO MAINTAIN EVEN 5 PERCENT
SEVERE PROBABILITIES.

...PIEDMONT INTO COASTAL PLAIN OF NORTH CAROLINA INTO VIRGINIA...
MODELS ARE SUGGESTIVE THAT A WEAK MID-LEVEL IMPULSE CROSSING THE
CENTRAL APPALACHIANS COULD CONTRIBUTE TO THE INITIATION OF STORMS TO
THE EAST OF THE HIGHER TERRAIN.  STRONG DAYTIME HEATING WITHIN THE
LEE SURFACE TROUGH MAY CONTRIBUTE TO RELATIVELY DEEP BOUNDARY LAYER
MIXING...WITH TEMPERATURES REACHING THE 90S ACROSS THE PIEDMONT OF
NORTH CAROLINA INTO SOUTHERN/CENTRAL VIRGINIA...ALONG THE WESTERN
EDGE OF RICHER BOUNDARY LAYER MOISTURE.  THIS INTERFACE MAY PROVIDE
THE FOCUS FOR INCREASINGLY VIGOROUS STORM DEVELOPMENT LATE WEDNESDAY
AFTERNOON.  HOWEVER...IT REMAINS UNCLEAR WHETHER DEEP LAYER
FLOW/SHEAR WILL BE STRONG ENOUGH TO CONTRIBUTE TO CONVECTIVE
ORGANIZATION AND SUPPORT ANYTHING BEYOND VERY ISOLATED/LOCALIZED
DOWNBURSTS.  LOW SEVERE PROBABILITIES MAY NEED TO BE CONSIDERED IN
LATER OUTLOOKS FOR THIS PERIOD.

...CENTRAL HIGH PLAINS...
IT DOES NOT APPEAR OUT OF THE QUESTION THAT STEEPENING OF MID-LEVEL
LAPSE RATES AND LOW-LEVEL MOISTURE RETURN MAY CONTRIBUTE TO THE
EVOLUTION OF AN ENVIRONMENT AT LEAST MARGINALLY CONDUCIVE TO
ISOLATED SUPERCELL STORMS...PARTICULARLY WEDNESDAY EVENING...WITH
THE DEVELOPMENT OF A SOUTHERLY LOW-LEVEL JET.  LOW SEVERE WEATHER
PROBABILITIES MAY NEED TO BE CONSIDERED IN LATER OUTLOOKS FOR THIS
PERIOD...ACROSS PARTS OF EASTERN COLORADO AND NORTHEAST NEW MEXICO
INTO ADJACENT PORTIONS OF KANSAS AND THE PANHANDLE REGION.

..KERR.. 07/07/2015




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