Severe Storm Outlook Narrative (AC)
Issued by NWS

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205
ACUS02 KWNS 280559
SWODY2
SPC AC 280558

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT THU JUL 28 2016

VALID 291200Z - 301200Z

...THERE IS A MRGL RISK OF SVR TSTMS FOR PARTS OF THE SRN
PLAINS...OZARK PLATEAU...AND MID-MS VALLEY...

...THERE IS A MRGL RISK OF SVR TSTMS FOR PARTS OF THE MID-ATLANTIC
REGION INTO LONG ISLAND NY...

...SUMMARY...
ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS PARTS OF
THE MID-ATLANTIC REGION TO LONG ISLAND. OTHER STRONG STORMS ARE
POSSIBLE FOR PARTS OF THE SOUTHERN PLAINS TO THE MID-MISSISSIPPI
VALLEY.

...SYNOPSIS...
BROAD CYCLONIC FLOW WILL EXTEND FROM THE GREAT PLAINS TO THE
ATLANTIC COAST. AN EMBEDDED SHORTWAVE TROUGH AND ASSOCIATED SFC
CYCLONE WILL ADVANCE QUICKLY FROM THE MID-ATLANTIC REGION ACROSS SRN
NEW ENGLAND BEFORE MOVING OFFSHORE DURING THE EVENING. A SEPARATE
MIDLEVEL SPEED MAX WILL WEAKEN WHILE MOVING ACROSS THE OZARK PLATEAU
TOWARDS THE MID-MS VALLEY. A PERSISTENT MIDLEVEL ANTICYCLONE WILL
GRADUALLY SHIFT EWD TO NEAR THE FOUR CORNERS AS A PRONOUNCED TROUGH
AMPLIFIES ACROSS WRN CANADA INTO THE PAC NW.

...MID-MS VALLEY/LOWER-OH VALLEY WWD INTO PARTS OF THE SRN PLAINS...

HIGH UNCERTAINTY FORECAST WILL UNFOLD DURING THE FRI/D2 PERIOD 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 TO SET UP NEAR THE RED RIVER VALLEY AND BE
ONE FOCUS FOR TSTM DEVELOPMENT WITHIN A MOISTURE-RICH AIR MASS.
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/DESTABILIZATION OCCURS. UNCERTAINTY INCREASES WITH NWD
EXTENT INTO OK AND THE ERN TX/OK PANHANDLES...ESPECIALLY WITH THE
DEGREE OF AIR MASS RECOVERY THAT CAN OCCUR. STRENGTHENING NOCTURNAL
LLJ MAY SUPPORT ELEVATED TSTM DEVELOPMENT OVERNIGHT ACROSS PORTIONS
OF WRN OK AND THE ERN TX PANHANDLE.

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 PRIMARY EWD MOVING IMPULSE AND NEAR
ACCOMPANYING SFC BOUNDARY. THIS AREA WILL BE POSITIONED WITHIN A
BELT OF RELATIVELY STRONGER MIDLEVEL WLY FLOW /E.G. 20-30 KT/...WITH
PRIMARY UNCERTAINTY BEING 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.

...MID-ATLANTIC REGION INTO LONG ISLAND NY...
A LOW-LEVEL CYCLONE ASSOCIATED WITH A FAST-MOVING SHORTWAVE IMPULSE
WILL TRACK FROM THE DELMARVA PENINSULA NEWD ALONG COASTAL SRN NEW
ENGLAND FRI MORNING. ASSOCIATED BELT OF 30-40 KT OF LOW-LEVEL FLOW
WITHIN WARM CONVEYOR WILL SUPPORT STRONG WIND PROFILES E OF THE COLD
FRONT AND SFC LOW FROM THE CHESAPEAKE BAY NEWD ACROSS LONG ISLAND
NY. MODEL FORECAST SOUNDINGS SUGGESTS THE AIR MASS MAY BECOME
MARGINALLY UNSTABLE MID-LATE MORNING WITH MODEST DIURNAL HEATING
OCCURRING AMIDST RICH TROPOSPHERIC MOISTURE. A FEW SMALL CLUSTERS OR
LINE SEGMENTS CAPABLE OF STRONG WIND GUSTS WILL BE POSSIBLE PRIOR TO
THE COLD FRONT QUICKLY MOVING OFFSHORE.

...NERN NM AND SERN CO...
UPSLOPE FLOW ACROSS THE RATON MESA INTO THE FRONT RANGE OF SERN CO
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.

..ROGERS.. 07/28/2016

$$



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