Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 230956
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
556 AM EDT TUE SEP 23 2014

.SYNOPSIS...
HIGH PRESSURE BUILDS ACROSS THE NORTHERN MID ATLANTIC TODAY AS LOW
PRESSURE DEVELOPS OFF THE SOUTHEAST COAST. THIS AREA OF LOW PRESSURE
WILL SLOWLY MOVE UP THE COAST WEDNESDAY AND THURSDAY.
MEANWHILE...HIGH PRESSURE WILL REMAIN ANCHORED ACROSS NEW ENGLAND.

&&

.NEAR TERM /THROUGH TONIGHT/...
CURRENT GOES WV IMAGERY SHOWS A HIGHLY MERIDIONAL MID/UPPER PATTERN
ACROSS ERN NORTH AMERICA...WITH A VIGOROUS TROUGH DIGGING ACROSS THE
GULF COAST...AND DEEP SSW FLOW ALONG THE EAST COAST. AT THE
SURFACE...1026MB HIGH PRESSURE IS CENTERED OVER THE OHIO
VALLEY...AND THE COLD FRONT THAT CROSSED THE REGION YESTERDAY
MORNING HAS STALLED IN VICINITY OF THE GULF STREAM. THIS GENERAL
PATTERN WILL PERSIST THROUGH THE DAY. A CONSIDERABLE AMOUNT OF
CIRRUS WILL CONTINUE TO STREAM NNE WITHIN THE SSW FLOW ALOFT...AND
THIS WILL PRODUCE PARTLY TO MOSTLY CLOUDY CONDITIONS. LOW-LEVEL NE
FLOW WILL RESULT IN A COOLER DAY...WITH HIGHS RANGING FROM THE UPPER
60S ALONG THE COAST...TO THE LOW 70S INLAND.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
SURFACE HIGH PRESSURE SHIFTS TO NRN NEW ENGLAND TONIGHT AND BUILDS
TO ~1035MB. MEANWHILE...AN INVERTED TROUGH WILL BEGIN TO SHARPEN OFF
THE SOUTHEAST COAST IN RESPONSE TO THE SLOW NE ADVANCEMENT OF THE
GULF COAST TROUGH. FORECAST SOUNDINGS INDICATE A SIGNIFICANT LAYER
OF DRY AIR CENTERED AROUND 800MB...AND GIVEN THIS MOST OF THE REGION
SHOULD REMAIN DRY OVERNIGHT...WITH THE EXCEPTION OF NE NC WHERE
20-30% POPS WILL BE FORECAST AFTER 06Z.

THE PATTERN BECOMES HIGHLY BLOCKED WEDNESDAY INTO WEDNESDAY NIGHT AS
A CLOSED 700MB HIGH BUILDS N OF A WEAK LOW OVER THE SOUTHEAST
STATES. AT THE SURFACE...HIGH PRESSURE REMAINS ANCHORED OVER NEW
ENGLAND AS A WEAK COASTAL LOW DRIFTS UP THE COAST. A SUBSTANTIAL
PLUME OF MOISTURE WILL ADVECT NORTHWARD FROM THE GULF STREAM
WEDNESDAY INTO WEDNESDAY NIGHT AND HIT A +2 ST DEV MID AND SURFACE
HIGH N OF THE REGION. THIS WILL RESULT IN A STRONG EASTERLY LLJ AND
BRING THE POTENTIAL FOR HEAVY RAINFALL. MODEL DERIVED QPF ON AVERAGE
SUPPORTS 1.5-2.0IN STORM TOTAL E OF I-95...ALTHOUGH THERE IS THE
POTENTIAL FOR LOCALLY HIGHER AMOUNTS. SPATIAL AND TIMING DIFFERENCES
STILL EXIST AMONGST NUMERICAL MODEL GUIDANCE. THIS FORECAST
GENERALLY FOLLOWS THAT OF THE 23/00Z NAM/ECMWF...WHICH FOCUSES RAIN
OVER SE PORTIONS WEDNESDAY AFTERNOON/EVENING...AND THEN UP THE COAST
OVERNIGHT WEDNESDAY NIGHT...BUT CONFIDENCE DOES REMAIN RATHER LOW.
THE PATTERN BEGINS TO RELAX THURSDAY...ALTHOUGH LINGERING CLOUD
COVER IS EXPECTED ALONG WITH A CHC OF RAIN CONTINUING MAINLY OVER NE
PORTIONS.

A NE WIND WILL BECOME RATHER BREEZY WEDNESDAY AFTERNOON AND EVENING
ALONG THE COAST...WITH SPEEDS AVERAGING ~20MPH...WITH GUSTS OF
25-30MPH. HIGHS WEDNESDAY AND THURSDAY SHOULD RANGE FROM THE UPPER
60S/AROUND 70 OVER THE PIEDMONT...TO THE LOW/MID 70S ALONG THE
COAST...BUT WILL ULTIMATELY BE DEPENDENT ON CLOUD COVER AND RAIN.
LOWS SHOULD GENERALLY RANGE THROUGH THE 60S...WITH UPPER 50S
POSSIBLE OVER THE NW PIEDMONT COUNTIES.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MODEL DIFFERENCES CONTINUE TO MAKE FOR A RATHER LOW CONFIDENCE
XTNDD PERIOD. NOT QUITE BUYING THE XTNDD WET PERIOD (CUT-OFF LOW)
ECMWF HAS PAINTED ACROSS THE AREA (GIVEN TIME OF YEAR AND PREVIOUS
PERFORMANCES) SO HAVE GONE WITH THE DRYER GFS / CANADIAN SOLN. GIST
IS THAT OCEANIC MOISTURE WILL BE BATTLING THE DRY AIR FROM THE HIGH
PRS TO THE NORTH. LAST TIME THIS HAPPENED...THE HIGH WON OUT EXCEPT
ALONG COASTAL SECTIONS. HAVE TRENDED THIS FORECAST IN THE SAME
MANNER MEANING THE BEST CHCS FOR PCPN WILL BE ALONG COASTAL SCTNS
WITH MAINLY DRY CONDITIONS WEST OF THE CHES BAY THRU THE WEEKEND.
COOLEST DAY FRI. HIGHS IN THE L-M70S. 75-80 BOTH SAT & SUN. LOWS
M50S-M60S.

NEXT TROF OF LOW PRESSURE MOVES EAST ACROSS THE MTS MON. LOW CHC
POPS WITH THIS FEATURE FOR NOW. HIGHS 75-80.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS PREVAIL EARLY THIS MORNING OVER THE TAF SITES AS HIGH
PRESSURE BUILDS IN FROM THE WEST. PRESSURE GRADIENT OVER THE REGION
HAS RESULTED IN GOOD MIXING TONIGHT AND WINDS GENERALLY 8-12 KT. NLY
SURGE OVER THE BAY IS PRODUCING LOCALLY STRONGER WINDS AT
KORF...WITH A FEW GUSTS UP TO 25 KT. OTHERWISE...BKN-OVC HIGH CLOUDS
AOA 20K FT AGL SPREADING OVER THE REGION FROM THE SW.

FOR TODAY...HIGH PRESSURE BUILDS JUST NORTH OF THE LOCAL AREA WITH A
SFC RIDGE EXTENDING INTO THE SE COASTAL PLAINS. PRESSURE GRADIENT
BTWN HIGH PRESSURE AND A FRONTAL BOUNDARY OFF THE SE COAST WILL
RESULT IN NE WINDS 10-15 KT WITH A FEW GUSTS UP TO 20-25 KT DURING
PEAK HEATING. OTHERWISE...VFR CIGS/VSBYS WITH A FEW MID LEVEL CLOUDS
4-6K FT AGL AND HIGH CLOUDS AOA 20K FT. MEASURABLE PRECIP REMAINS
SOUTH OF THE REGION.

LOW PRESSURE FORECAST TO DEVELOP ALONG THE COASTAL FRONT WEDS AND
LIFT TOWARD THE REGION INTO WEDS NIGHT. THIS WILL BRING PERIODS OF
RAIN...ESPECIALLY NEAR THE COAST...ALONG WITH REDUCED VSBY AND LOW
CIGS. BREEZY NE WINDS ALSO EXPECTED ALONG THE COAST.

&&

.MARINE...
ONGOING SECONDARY CAA SURGE HAS PRODUCED NLY WINDS OF 15-20 KT WITH
GUSTS TO 25 KT OVER THE WATERS. AS A RESULT...SCA HEADLINES WERE
RAISED LATE LAST EVENING FOR THE BAY/LOWER JAMES/CURRITUCK SOUND.
WAVES AVG 2-3 FT AND UP TO 4 FT IN THE MOUTH OF THE BAY. EXPECT THIS
TREND TO CONTINUE THRU MID MORNING AS HIGH PRESSURE BUILDS OVER THE
WATERS...RELAXING THE GRADIENT WINDS AND VEERING THE FLOW TO THE NE.
SPEEDS AVG 10 KT OVER THE BAY/RIVERS/SOUND AND 10-15 KT OVER THE
COASTAL WATERS TODAY AS HIGH PRESSURE BUILDS INTO NEW ENGLAND. LOW
PRESSURE FORECAST TO DEVELOP ALONG A STALLED FRONTAL BOUNDARY OFF
THE SE COAST LATE TONIGHT-WEDS...LIFTING NWD OVER THE WATERS BY WEDS
NIGHT. PRESSURE GRADIENT STRENGTHENS AS NE WINDS INCREASE TO SCA
CONDITIONS. PERSISTENT NE WINDS WILL PUSH SEAS TO 4-5 FT IN THE SRN
WATER (SOUTH OF CAPE CHARLES LIGHT) BEGINNING LATE TONIGHT.
SPEEDS/SEAS/WAVES INCREASE ACROSS THE REST OF THE WATERS THRU THE
DAY WEDS. COMBINATION OF STRONG LOW LEVEL GRADIENT WINDS...NE FLOW
AND WARM WATERS WILL RESULT IN SOLID SCA CONDITIONS WEDS INTO WEDS
NIGHT. 20-25 KT...GUSTS TO 30 KT FOR THE COASTAL WATERS AND LOWER
BAY...15-20 KT WITH GUSTS TO 25 KT ELSEWHERE. WAVES EXPECTED TO
BUILD TO 4-5 FT WITH 3-4 FT IN THE LOWER JAMES AND 2 FT IN THE
SOUND. WHILE GALES APPEAR POSSIBLE...SPATIAL DIFFERENCES IN THE
MODELS LEND TO A LOWER CONFIDENCE FOR GALES...SO WILL LEAVE AT SCA
WITH THIS FORECAST PACKAGE. SEAS WILL ALSO RESPOND...QUICKLY
BUILDING UPWARDS OF 8-10 FT (POSSIBLE HIGHER 20 NM OUT). FLOW AND
WAVE DIRECTION WILL RESULT IN NEARSHORE WAVES OF 5-7 FT. HIGH SURF
ADVISORIES MAY BE NEEDED WEDS.

MODELS BRING THE SFC LOW OVER THE BAY WEDS NIGHT...BUT DIFFER
THEREAFTER. SOME MODELS KEEP THE SFC LOW OVER THE REGION WHILE OTHERS
PUSH IT OUT TO SEA THURS. HAVE OPTED TO PUSH SCA HEADLINES IN THE
COASTAL WATERS AND BAY THRU 4TH PERIOD (WEDS NIGHT). WATERS REMAIN
BTWN HIGH PRESSURE TO THE NW AND LOW PRESSURE OVER THE WRN ATLANTIC
THRU THE WEEK.

&&

.TIDES/COASTAL FLOODING...
PERSISTENT NE FLOW IS EXPECTED TO DEVELOP TODAY AND STRENGTHEN WEDNESDAY
INTO THURSDAY AS HIGH PRESSURE REMAINS ANCHORED OVER NEW
ENGLAND...AND LOW PRESSURE DEVELOPS OFF THE CAROLINA COAST. CURRENT
GUIDANCE SUGGESTS TIDAL DEPARTURES RISE TO AROUND 1 FOOT ABOVE NORMAL
WEDNESDAY MORNING INTO THURSDAY. WHILE ASTRONOMICAL TIDES ARE
RELATIVELY LOW AROUND THE NEW MOON...SOME LOCATIONS IN THE BAY
(INCLUDING SEWELLS POINT) WILL LIKELY APPROACH MINOR FLOODING
THRESHOLDS. MD BEACHES MAY ALSO APPROACH MINOR FLOODING
THRESHOLDS. NO HEADLINES IN EFFECT ATTM.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...MODERATE RIP CURRENT RISK THROUGH THIS EVENING FOR MDZ025.
NC...MODERATE RIP CURRENT RISK THROUGH THIS EVENING FOR NCZ102.
VA...MODERATE RIP CURRENT RISK THROUGH THIS EVENING FOR VAZ098>100.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM WEDNESDAY TO MIDNIGHT EDT
     WEDNESDAY NIGHT FOR ANZ635>638.
     SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR
     ANZ630>634-638-656-658.
     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EDT
     THURSDAY FOR ANZ634-656-658.
     SMALL CRAFT ADVISORY FROM 6 AM WEDNESDAY TO 6 AM EDT THURSDAY
     FOR ANZ630>632-650-652-654.
     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO MIDNIGHT EDT
     WEDNESDAY NIGHT FOR ANZ633.

&&

$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ
LONG TERM...MPR
AVIATION...SAM
MARINE...SAM
TIDES/COASTAL FLOODING...SAM





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