Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 132009
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
409 PM EDT SUN JUL 13 2014

.SYNOPSIS...
LOW PRESSURE MOVES ACROSS THE GREAT LAKES REGION WITH A TRAILING
COLD FRONT APPROACHING FROM THE NORTHWEST LATE MONDAY INTO
TUESDAY. THE FRONT IS EXPECTED TO SLOWLY PUSH THROUGH THE LOCAL
AREA TUESDAY AFTERNOON AND NIGHT. THE FRONT PUSHES OFF THE COAST
ON WEDNESDAY AS HIGH PRESSURE BEGINS TO BUILD IN FROM THE
NORTHWEST.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
LATEST ANALYSIS SHOWING SFC HIGH PRESSURE WELL OFF THE COAST...WITH
A DEEPENING LOW PRESSURE SYSTEM OVER ONTARIO CANADA. SOME WEAK SFC
TROUGHINESS STILL NOTED OVER THE LOCAL AREA...AND SOME SCATTERED
SHOWERS W/ EMBEDDED TSTMS HAVE PUSHED ACRS PORTIONS OF CENTRAL AND
ERN VA AIDED BY SOME WEAK SHORTWAVE ENERGY ALOFT...ALTHOUGH THESE
HAVE BEEN FAIRLY WEAK AND SHORT-LIVED AS DEEP LAYER SHEAR IS ONLY
ABOUT 15 KT. A MORE POTENT SHORTWAVE AND SFC COLD FRONT IS PUSHING
A LARGER AREA OF CONVECTION THROUGH NY STATE AND THE UPPER OH
VALLEY. SOME OF THIS MAY HOLD TOGETHER OVERNIGHT TO KEEP SOME 20%
POPS OVER THE ERN SHORE GOING AFTER MIDNIGHT...OTHERWISE VARIABLY
CLOUDY AND WARM/HUMID OVERNIGHT W/ LOWS MAINLY 70-75 F.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
ANOMALOUSLY DEEP UPPER LOW OVER SOUTHERN CANADA LOOKS TO PUSH A STRONG
SHORTWAVE SE THROUGH THE GREAT LAKES/UPPER MIDWEST ON MON. THIS
ALLOWS LOW LEVEL FLOW FROM THE SW TO INCREASE FURTHER. SPC NOW HAS
MUCH OF THE CWA OUTLINED IN A SLIGHT RISK FOR SEVERE TSTMS ALTHOUGH
SOME UNCERTAINTY REMAINS. A STRONG SW FLOW IN THE BOUNDARY LAYER
OFTEN DRIES THE AKQ CWA OUT (ESPECIALLY SE VA/NE NC). FOR
NOW...WILL MAINTAIN HIGH CHC POPS DEVELOPING BY MID-LATE MON AFTN
OVER THE NW COUNTIES TAPERED TO ONLY 20% POPS IN SE VA/NE NC.
HIGHS 90-95 F AGAIN. POPS ACTUALLY SHOULD INCREASE SOMEWHAT MON
EVENING ALL THE WAY TO THE COAST AS LOW-LEVEL JET ENERGY INCREASES
(AND A BETTER CHANCE OF STRONG TO SVR STORMS MAY MATERIALIZE)...SO
WILL HAVE AT LEAST 30-40% POPS ALL ZONES. WARM/HUMID MON NIGHT W/ LOWS
MAINLY 70-75.

BY TUE...MODELS INTO DECENT AGREEMENT W/ TIMING...THE SFC COLD
FRONT MOVES INTO THE REGION AND UPPER LEVEL SUPPORT INCLUDING RRQ
FORCING FROM THE UPPER JET ARRIVES LATER IN THE DAY. STILL
SOMEWHAT UNCLEAR AS TO PRECIP COVERAGE IN THE MORNING HRS DUE TO
VARYING MODEL SOLUTIONS AND PRESENCE OF OLD BOUNDARIES FROM MON
NIGHT. WILL CARRY HIGH CHC POPS MOST AREAS IN THE AM HRS WITH
LIKELY POPS BY AFTN ALL ZONES...SOME SEVERE POTENTIAL EXISTS
(MAINLY STRAIGHT LINE WIND THREAT) AS DEEP LAYER SHEAR VALUES
INCREASE TO > 30 KT (NOT BAD FOR TIME OF YR). SEVER THREAT WILL
TEND TO TRANSITION TO MAINLY A HEAVY RAIN THREAT BY TUE NIGHT AS
THE COLD FRONT SLOWLY MOVES EAST. BEST CHANCE OF SEVERE TSTMS ON
TUESDAY (SLIGHT RISK BY SPC) WILL BE ACROSS SE VA AND NE NC WHERE
BEST BUOYANCY/INSTABILITY WILL BE LOCATED ALONG AND SOUTH OF THE
COLD FRONT. LOCALIZED FLOODING MAY ALSO BE AN ISSUE...AND MAY
PERSIST OVERNIGHT TUE INTO WED AM GIVEN SLOW MOVEMENT OF THE
FRONT...STRONG FORCING FOR ASCENT...AND PW`S IN EXCESS OF 2
INCHES. WILL CONTINUE TO HIGHLIGHT THESE THREATS IN THE HWO. IF
TEMPERED BY CLOUDS/PCPN HIGHS TUE WOULD GENERALLY REMAIN IN THE
MID/UPR 80S...BUT COULD REACH INTO THE LOWER 90S IF SOME SUN
DEVELOPS FOR A FEW HRS THROUGH MIDDAY. HAVE BLENDED THESE 2
SCENARIOS FOR FCST HIGHS...GENLY GOING UPPER 80S NW TO AROUND 90 F
SE. LOWS TUE NIGHT MID 60S NW TO AROUND 70 F SE. ON WED...MODELS
NOW ALSO INTO DECENT CONSENSUS REGARDING THE SFC FRONT
POSITION...JUST PUSHING OFF THE SE VA/NE NC COAST AS OF 12Z/WED.
LOW LEVEL FLOW SHIFTS TO THE N MOST AREAS WITH A COOLER DRIER
AIRMASS EVENTUALLY OVERSPREADING THE REGION FROM THE W/NW. LIKELY
POPS WILL STILL PREVAIL EARLY ON ALONG THE COAST...BUT SKIES
SHOULD BECOME PARTLY SUNNY ALONG/WEST OF I-95 BY MID MORNING.
COOLER W/ HIGHS IN THE UPPER 70S TO LWR-MID 80S.





&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
LONG TERM PERIOD WILL FEATURE SLGTLY BLO NORMAL TEMPS AND FREQUENT
CHANCES FOR PRECIP. FOR THU...SFC HI PRES WILL BE CENTERED OVR THE
OH VALLEY WITH A BROAD AREA OF WEAK LO PRES OVR THE SE STATES...AND
MID-LEVEL ENERGY APPROACHING FM THE CNTRL PLAINS/MIDWEST. WITH LO
PRES NEAR THE CAROLINAS...COULD SEE SOME SHRAS/TSTMS OVR SE AREAS OF
THE FA...BUT NOTHING WIDESPREAD EXPECTED. HI TEMPS AVG IN THE MID
80S. THE AFOREMENTIONED SFC HI MOVES OFF THE NE CST FRI...WITH
APPROACHING MID-LEVEL ENERGY LEADING TO A CONTINUED CHANCE FOR
SHRAS/TSTMS (30-40% POPS). THE PATTERN CONTINUES INTO SAT AND SUN
WITH CHANCE POPS. EXACT TIMING OF THE PRECIP IS DIFFICULT TO PREDICT
WITH THIS BEING SEVERAL DAYS OUT. HI TEMPS FRI THRU SUN IN THE MID
80S...WITH LO TEMPS IN THE MID TO UPR 60S.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
SFC HI PRES WILL MOVE FARTHER OUT TO SEA THIS AFTN INTO MON. SSW
WINDS ARND 10 KT WITH GUSTS TO ARND 20 KT...ESPLY AT RIC AND
SBY...WILL DIMINISH TO 5 TO 10 KT ACRS THE AREA FM 23Z TO 13Z MON
MORNG. MAINLY VFR CONDITIONS WILL CONTINUE WITH JUST A SLGT CHC
OF A SHRA/TSRA INTO EARLY THIS EVENG. A WEAK SHRTWV TROF MOVES
ACRS THE REGION MON AFTN/EVENG...AND THIS WILL BRING A HIGHER CHC
OF SHRAS/TSRAS...SOME OF WHICH COULD PRODUCE STRONG WIND GUSTS. A
COLD FRONT WILL CONTINUE TO BRING THE POTENTIAL FOR SHRAS/TSRAS
TUE INTO WED.

&&

.MARINE...
LATEST SFC ANALYSIS REVEALS HI PRES OFF THE SE/CAROLINA CST AND LO
PRES WELL N OF THE LOCAL AREA. S WINDS CONTINUE AHEAD OF A LEE TROF
OVR THE PIEDMONT...AND A SLGT INCREASE IN THE PRES GRADIENT WILL BE
ENUF TO BRING WINDS CLOSE TO SCA THRESHOLDS OVR THE BAY THIS EVENG.
DID HOLD OFF ON ANY HEADLINES FOR NOW WITH SUSTAINED WINDS EXPECTED
TO MAINLY BE ~15 KT FOR THE BAY AND 15-20 KT FOR CSTL WTRS. WAVES UP
TO 3 FT OVR THE NRN BAY ZONES AND UP TO 3-4 FT OVR NRN CSTL WTRS.
SIMILAR WAVES/WINDS/SEAS INTO MON AS A COLD FRNT APPROACHES FM THE W
AND HI PRES REMAINS OFFSHORE. THIS FRNT WILL SLOWLY CROSS THE MID
ATLANTIC COAST TUE NGT INTO WED. SEAS MAY APPROACH 5 FT MON NGT BUT
WITH THIS BEING 3RD PERIOD AND LO CONFIDENCE...WILL NOT ISSUE A SCA.
THE WIND SHOULD REMAIN SSW THROUGH TUE WITH SPEEDS OVR THE OCEAN
CONTINUING TO AVG 15-20 KT...AND 10-15 KT ELSEWHERE. A WIND SHIFT TO
THE NE IS EXPECTED BEHIND THE FRNT. AT THIS TIME THERE IS NOT MUCH
OF A COOL AIR SURGE EXPECTED BEHIND THE FRNT...SO POST-FRNTL WIND
SPEEDS ARE FORECAST TO REMAIN AOB 10 KT. LGT ONSHORE FLOW IS
EXPECTED TO CONTINUE LATER IN THE WEEK AS HI PRES BLDS N OF THE
REGION AND WEAK LO PRES LINGERS OVER THE SE.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...LKB
NEAR TERM...LKB
SHORT TERM...JDM/LKB
LONG TERM...MAS
AVIATION...TMG
MARINE...MAS






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