Severe Storm Outlook Narrative (AC)
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ACUS02 KWNS 281742
SWODY2
SPC AC 281741

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1241 PM CDT THU JUL 28 2016

VALID 291200Z - 301200Z

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE MID-ATLANTIC STATES TO
COASTAL SOUTHERN NEW ENGLAND...

...THERE IS A MRGL RISK OF SVR TSTMS FROM PORTIONS OF THE SOUTHERN
PLAINS OT THE MID MS VALLEY...

...SUMMARY...
ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS PARTS OF
THE MID-ATLANTIC REGION TO LONG ISLAND AND COASTAL AREAS OF SOUTHERN
NEW ENGLAND DURING FRIDAY MORNING AND AFTERNOON.  OTHER STRONG
STORMS ARE POSSIBLE FOR PARTS OF THE SOUTHERN PLAINS TO THE
MID-MISSISSIPPI VALLEY.

...SYNOPSIS...
A BROAD CYCLONIC FLOW REGIME WILL PREVAIL THROUGH FRIDAY AND FRIDAY
NIGHT EAST OF THE ROCKIES.  MEANWHILE...THE UPPER RIDGE CENTERED
OVER THE SOUTHWEST U.S. WILL BEGIN TO DAMPEN...ESPECIALLY DURING THE
LATTER HALF OF THIS FORECAST PERIOD...AS HEIGHTS FALL WITH THE
APPROACH OF AN AMPLIFYING TROUGH INTO WESTERN CANADA.  A COUPLE OF
IMPULSES WILL TRANSLATE TO THE EAST-NORTHEAST ACROSS THE
MID-ATLANTIC STATES THROUGH OR JUST OFF THE SOUTHERN NEW ENGLAND
COASTAL AREAS.  AN AREA OF LOW PRESSURE IS EXPECTED TO TRACK TO THE
EAST-NORTHEAST ALONG A WARM FRONT THAT SHOULD EXTEND PARALLEL TO THE
SOUTHERN NEW ENGLAND COAST...WITH SOME VARIABILITY IN THE LOCATION
OF THE BOUNDARY.

...MID-ATLANTIC REGION TO LONG ISLAND AND SOUTHERN NEW ENGLAND...
A LEAD MIDLEVEL IMPULSE SHOULD TRACK ACROSS EXTREME SOUTHERN NEW
ENGLAND FRIDAY MORNING TO THE EARLY AFTERNOON.  GIVEN SOME
UNCERTAINTY WITH THE PLACEMENT OF A WARM FRONT...EITHER ALONG
COASTAL SOUTHERN NEW ENGLAND OR JUST OFFSHORE...THIS OUTLOOK HAS
EXPANDED THE MARGINAL SEVERE-WEATHER RISK NORTH AND NORTHEAST.

STORMS SHOULD BE ONGOING AT 12Z FRIDAY ATTENDANT TO A FAST MOVING
LEAD MIDLEVEL IMPULSE.  ASSOCIATED BELT OF 30-40 KT OF LOW-LEVEL
SOUTH-SOUTHWESTERLY WINDS  WITHIN THE WARM CONVEYOR WILL SUPPORT
STRONG WIND PROFILES E OF THE COLD FRONT AND SFC LOW FROM THE
CHESAPEAKE BAY NEWD ACROSS FAR SOUTHERN NEW ENGLAND INCLUDING THE
OFFSHORE ISLANDS.  MARGINAL TO MODERATE INSTABILITY AND
STRENGTHENING BULK SHEAR AS WEST-SOUTHWESTERLY 500-MB FLOW OF 50-60
KT SPREADS ACROSS THE MID-ATLANTIC COASTAL AREA TO SOUTHERN NEW
ENGLAND WILL SUPPORT STORM ORGANIZATION.  ENHANCED LOW-LEVEL SHEAR
IN VICINITY OF THE WARM FRONT SUGGESTS A BRIEF TORNADO CANNOT BE
RULED OUT.  OTHERWISE...DAMAGING WINDS WILL BE POSSIBLE WITH ANY
SMALL CLUSTERS OR LINE SEGMENTS THAT DEVELOP WITH THE MORNING
ACTIVITY AND OVER EASTERN VA ATTENDANT TO THE NEXT UPSTREAM
SHORTWAVE TROUGH CROSSING THE AREA FRIDAY AFTERNOON.

...MID-MS VALLEY/LOWER-OH VALLEY SOUTHWEST TO THE SOUTHERN PLAINS...

FORECAST CONFIDENCE REMAINS LOW WITH THIS PORTION OF THE DAY 2
OUTLOOK AS MESOSCALE DETAILS WILL BE DEPENDENT ON EARLY MORNING MCS
MOVING ACROSS PARTS OF OK/TX...WHICH COULD POSE A LINGERING STRONG
WIND THREAT INTO EARLY PORTIONS OF THE PERIOD.  MOST LIKELY SCENARIO
IS FOR AN OUTFLOW BOUNDARY FROM THE DAY 1 MCS TO BE THE ACTIVE FOCI
FOR AFTERNOON THUNDERSTORM DEVELOPMENT.  HOWEVER...THE PLACEMENT OF
THIS BOUNDARY BY FRIDAY AFTERNOON REMAINS UNCERTAIN...WITH IT BEING
ACROSS CENTRAL OK OR NEAR THE RED RIVER VALLEY.  DEEP-LAYER SHEAR
WILL BE WEAK AS THIS AREA IS POSITIONED ALONG THE  SRN FRINGE OF
N-NWLY FLOW ALOFT...BUT A THREAT FOR STRONG WIND GUSTS MAY ACCOMPANY
LOOSELY ORGANIZED CONVECTION WHERE MORE ROBUST DIURNAL
HEATING/MODERATE INSTABILITY DEVELOPS.  UNCERTAINTY INCREASES WITH
NWD EXTENT INTO NORTHERN OK AND THE ERN TX/OK PANHANDLES...GIVEN THE
DEGREE OF AIR MASS RECOVERY THAT CAN OCCUR.OTHERWISE...STRENGTHENING
NOCTURNAL LLJ MAY SUPPORT ELEVATED TSTM DEVELOPMENT OVERNIGHT ACROSS
PORTIONS OF WRN OK AND THE ERN TX PANHANDLE AND POSSIBLY INTO
SOUTHERN KS.

FARTHER E...INCLUDING THE OZARK PLATEAU NEWD TOWARDS THE MID-MS AND
LOWER-OH VALLEYS...CONVECTION SHOULD PERSIST OR REDEVELOP LATE
MORNING IN ASSOCIATION WITH AN EWD MOVING IMPULSE AND NEAR
ACCOMPANYING SURFACE BOUNDARY.  THIS AREA WILL BE POSITIONED WITHIN
A BELT OF RELATIVELY STRONGER MIDLEVEL WLY FLOW /E.G. 20-30 KT/...
WITH PRIMARY UNCERTAINTY REMAINING THE DEGREE OF HEATING THAT CAN
OCCUR. HOWEVER...THE POTENTIAL FOR A FEW STRONG WIND GUSTS MAY EXIST
FROM NRN AR/ERN MO INTO SRN IL THROUGH THE LATE AFTERNOON.

...NERN NM AND ERN CO...
UPSLOPE FLOW ACROSS THIS REGION SHOULD ENCOURAGE ISOLATED TSTM
DEVELOPMENT DURING THE AFTERNOON. NLY FLOW ALOFT WILL STRENGTHEN
ALONG THE ERN PERIPHERY OF A MIDLEVEL ANTICYCLONE OVER NRN AZ AND
RESULT IN MARGINALLY FAVORABLE SHEAR PROFILES ACROSS THE HIGH
PLAINS. THE MAGNITUDE OF MOISTURE ADVECTING WWD IS UNCERTAIN DUE TO
LOW-LEVEL TRAJECTORIES POTENTIALLY ORIGINATING IN A POST-MCS AIR
MASS OVER THE LOWER PLAINS...BUT A FEW STRONG STORMS MAY BE POSSIBLE
DURING THE MID-LATE AFTERNOON.

..PETERS.. 07/28/2016

$$


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