Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 171740
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
140 PM EDT FRI OCT 17 2014

.SYNOPSIS...
HIGH PRESSURE MOVES OFF THE SOUTHEAST COAST THROUGH TONIGHT. A
DRY COLD FRONT CROSSES THE MID ATLANTIC LATER SATURDAY. CANADIAN
HIGH PRESSURE BUILDS IN FROM THE NORTHWEST SATURDAY NIGHT AND
SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE MORNING WX ANALYSIS FEATURES DOUBLE BARRELED LOW PRESSURE
SYSTEM FROM THE UPPER GREAT LAKES TO THE ON/QB BORDER. THIS
STRUCTURE IS A COMBINATION OF THE EAST COAST TROUGH OF THE
PREVIOUS FEW DAYS AND A COMPACT UPPER LOW SLIPPING EAST ACROSS THE
UPPER MIDWEST FROM THE NORTHERN PLAINS/CANADIAN PRAIRIES. THE SFC
COLD FRONT ASSOCIATED WITH THE LATTER FEATURE EXTENDED SOUTH INTO
THE MIDDLE AND LOWER MISSOURI VALLEY AT 14Z. MEANWHILE TO THE
SOUTH, SFC HIGH PRESSURE REMAINS IN PLACE OVER THE DEEP SOUTH TO
THE EAST CENTRAL GULF COAST.

THE SURFACE RIDGE AXIS TO OUR WEST AT MIDDAY WILL SLIDE OFF THE
SOUTHEAST COAST THIS AFTN, ALLOWING THE LOW-LEVEL FLOW TO SHIFT TO
SSW. THIS WILL RESULT IN A MILD AND DRY DAY UNDER A MOSTLY SUNNY
SKY. HIGH TEMPERATURES SHOULD RANGE FROM THE MID 70S TO NEAR 80
DEG, WITH AFTERNOON DEWPOINTS DROPPING INTO THE UPPER 40S TO
AROUND 50.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
HIGH PRESSURE WILL SLIDE FARTHER OFFSHORE TONIGHT AS A VIGOROUS
MID/UPPER TROUGH DROPS THROUGH THE GREAT LAKES. LIGHT WAA WILL
CONTINUE RESULTING IN LOW TEMPERATURES ON THE WARM SIDE OF SEASONAL
AVERAGES...WITH READINGS AVERAGING IN THE LOW/MID 50S. THE TROUGH
PIVOTS ACROSS THE EASTERN GREAT LAKES SATURDAY...WITH THE ASSOCIATED
COLD FRONT APPROACHING FROM THE NW. HIGHS SATURDAY SHOULD REMAIN ON
THE MILD SIDE DUE TO DOWNSLOPING WNW FLOW...WITH MAXIMA AVERAGING IN
THE LOW/MID 70S...ALTHOUGH FAR NW PORTIONS COULD REMAIN IN THE UPPER
60S AS LOW-LEVEL THICKNESSES FALL THROUGH THE DAY. MOSTLY CLEAR
CONDITIONS ARE EXPECTED FRIDAY NIGHT...WITH PARTLY TO MOSTLY SUNNY
CONDITIONS DURING THE DAY SATURDAY.

THE TROUGH AXIS CROSSES THE MID ATLANTIC SATURDAY NIGHT AND PUSHES
OFFSHORE EARLY SUNDAY MORNING...FOLLOWED BY SHORTWAVE RIDGING LATER
SUNDAY. ANY VERTICAL ASCENT WITH THE TROUGH IS RATHER WEAK...AND THE
AIRMASS WILL REMAIN DRY. THIS SHOULD ONLY RESULT IN A PERIOD OF
MOSTLY CLOUDY CONDITIONS SATURDAY NIGHT...WITH POSSIBLY A FEW
SPRINKLES ACROSS FAR NRN PORTIONS. ANY CLOUD COVER SHOULD CLEAR OUT
QUICKLY SUNDAY MORNING AS AN EVEN DRIER AIRMASS ARRIVES WITH
CANADIAN HIGH PRESSURE BUILDING IN FROM THE NW. THE SURFACE COLD
FRONT CROSSES THE LOCAL AREA LATER SATURDAY AFTERNOON...WITH CAA
COMMENCING SATURDAY NIGHT. LOW TEMPERATURES SHOULD DROP INTO THE
LOW 40S OVER THE PIEDMONT BY SUNDAY MORNING...WITH MID/UPPER 40S
OVER MOST OF THE AREA...AND LOW/MID 50S FOR SE COASTAL LOCATIONS.
HIGHS SUNDAY SHOULD AVERAGE 60-65...WITH AFTERNOON DEWPOINTS
DROPPING INTO THE LOW/MID 30S (AND POTENTIALLY LOWER).

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AN ACTIVE NRN STREAM PATTERN IS EXPECTED TO CONTINUE SUNDAY NIGHT
INTO MONDAY. SURFACE HIGH PRESSURE IS FORECAST TO BE CENTERED OVER
THE REGION SUNDAY NIGHT/EARLY MONDAY MORNING. THIS SHOULD RESULT IN
A RATHER CHILLY AND CLEAR NIGHT WITH LOWS RANGING FROM THE MID/UPPER
30S OVER THE PIEDMONT...TO THE UPPER 40S/AROUND 50 OVER FAR SE
PORTIONS. SURFACE HIGH PRESSURE SLIDES OFFSHORE MONDAY AS YET
ANOTHER POTENT SYSTEM DIVES ACROSS THE GREAT LAKES. THIS WILL RESULT
IN A SHORT-LIVED WARMING TREND WITH HIGHS REBOUNDING INTO THE MID
60S TO AROUND 70 UNDER A MOSTLY SUNNY SKY. THE TROUGH IS EXPECTED TO
DIG THROUGH THE OHIO VALLEY MONDAY NIGHT AND TUESDAY AS LOW PRESSURE
DEVELOPS IN VICINITY OF THE GULF STREAM. THE TREND AMONGST 17/00Z
NUMERICAL GUIDANCE IS FOR THE TROUGH TO SETTLE OVER THE MID-ATLANTIC
WEDNESDAY INTO THURSDAY WITH SURFACE LOW PRESSURE LIFTING NNE OFF
THE COAST. POPS HAVE ACCORDINGLY BEEN ADJUSTED TO REFLECT AS 20-30%
CHC OF SHOWERS. THE PRESENCE OF THE UPPER SYSTEM AND LOW-LEVEL
NORTHERLY FLOW SHOULD RESULT IN CONSIDERABLE CLOUD COVER AND COOLER
TEMPERATURES. HIGHS TUESDAY ARE FORECAST TO RANGE FROM THE LOW 60S
NW...TO AROUND 70 SE...FOLLOWED BY MID 50S NW TO LOW/MID 60S SE
WEDNESDAY AND THURSDAY. OVERNIGHT LOWS SHOULD AVERAGE IN THE MID 40S
TO LOW 50S.

&&

.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE CENTERED OVER THE GULF COAST STATES HAS BUILD
NORTHWARD INTO THE MID ATLANTIC STATES AND WITH LOW MOISTURE IN
PLACE...IS PROVIDING MAINLY CLEAR SKY AND VFR CONDITIONS. THIS
HIGH EDGE OFF THE COAST TONIGHT AS A COLD FRONT APPROACHES FROM
THE WEST. THIS WILL SERVE TO KEEP THE SW FLOW A LITTLE STRONGER
OVERNIGHT AND ENOUGH TO KEEP FOG FROM DEVELOPING SO EXPECT VFR
CONDITIONS TONIGHT.

ON SAT MORNING...BETWEEN 9Z AND 15Z...THE COLD FRONT WILL CLEAR
THE AREA...BUT WITH LITTLE MOISTURE...NOT ANTICIPATING MUCH IN THE
WAY OF CLOUDS AND NO RAIN. THE WINDS WILL SHIFT TO THE NW AND WILL
INCREASE TO 10 TO 15 KTS. BY MID TO LATE AFTERNOON...THE COOLING
ALOFT WILL HELP TO GENERATE MORE CU AND A BROKEN DECK IS
POSSIBLE...BUT IT WILL REMAIN ABOVE 3K FT. THE CLOUDS WILL LINGER
INTO THE OVERNIGHT HOURS BEFORE CLEARING BEFORE SUNRISE SUNDAY

DRY AND VFR CONDITIONS PREVAIL SUNDAY THROUGH MONDAY NIGHT WITH
THE WINDS RELAXING SUNDAY AFTERNOON AS HIGH PRESSURE SETTLES OVER
THE AREA. THE NEXT CHANCE FOR MVFR CONDITIONS COMES ON TUESDAY AS
A COLD FRONT AND STRONG LOW PRESSURE SYSTEM MOVE INTO THE REGION.

&&

.MARINE...
SCA HEADLINES REMAIN IN EFFECT FOR THE COASTAL WATERS AS POWERFUL
HURRICANE GONZALO CONTINUES TO PUSH LONG PERIOD SWELL TOWARD THE
REGION. GONZALO WILL LIFT WELL OFF THE MID-ATLANTIC COAST THRU
SAT...WITH EFFECTS STILL FELT THRU THE WEEKEND. SEAS CURRENTLY AVG 4
TO 5 FT WITH THE SRN WATERS DROPPING BELOW 4 FT. HOWEVER...4 TO 5 FT
SEAS OBSERVED BEYOND 20 NM...SO SEAS COULD QUICKLY RETURN TO 5 FT SO
HEADLINES REMAIN UP. HEADLINES HAVE BEEN EXTENDED THROUGH SAT NIGHT.

OTHERWISE...HIGH PRESSURE OVER THE GULF STATES HAS NUDGED NEWD OVER
THE WATERS THIS MORNING. WLY WINDS AVG 10 TO 15 KT WITH WAVES 1-3 FT
IN THE BAY...HIGHEST AT THE MOUTH OF THE BAY. SFC RIDGE WILL PUSH
OFFSHORE TODAY AS A COLD FRONT APPROACHES FROM THE NW. THIS WILL
VEER THE WINDS TO THE SW. PRESSURE GRADIENT WILL RESPOND AS LOW
LEVEL WINDS INCREASE TO 30+ KT BY LATE TODAY. HOWEVER...WAA WILL
RESULT IN A STRONG INVERSION OVER THE WATERS. THIS WILL PREVENT THE
HIGHER VELOCITY WINDS ALOFT FROM MIXING TO THE WATER. HAVE NUDGED
WINDS TO 15 KT WITH GUSTS OF 18-19 KT...REMAINING BELOW SCA
CONDITIONS. COLD FRONT CROSSES THE WATERS SAT WITH FLOW BECOMING NW
LATE SAT INTO SAT NIGHT AS COOL CANADIAN HIGH PRESSURE DIVES OVER
THE GREAT LAKES REGION. GRADIENT WINDS REALLY RAMP UP SAT NIGHT WITH
SCA CONDITIONS EXPECTED ALL WATERS SAT NIGHT INTO SUN MORNING. NW
WINDS OF 20-25 KT WITH GUSTS UP TO 30 KT EXPECTED. WAVES INCREASE TO
3-4 FT AS SEAS REMAIN ELEVATED AT 5-7 FT. HAVE HELD OFF ON SCA
HEADLINES FOR THE BAY/RIVERS/SOUND AS IT REMAINS 4TH PERIOD...BUT
CONFIDENCE IS HIGH FOR SCA CONDITIONS. THE HIGH CENTER BUILDS OVER
THE WATERS SUN-MON...ALLOWING SUB-SCA CONDITIONS TO RETURN. WHILE
THERE REMAINS SOME MODEL UNCERTAINTY...THE NEXT COLD FRONT IS
EXPECTED TO CROSS THE WATERS ON TUES...ACCOMPANIES BY CAA AND MORE
SCA CONDITIONS. SYSTEM IS EXPECTED TO STALL OFF THE COAST THRU THE
END OF THE WEEK...WHICH MAY RESULT IN A PROLONGED PERIOD OF SCA
CONDITIONS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 4 AM EDT
     SATURDAY FOR ANZ630>634.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ650-652-654-
     656-658.

&&

$$
SYNOPSIS...AJZ/MAM
NEAR TERM...MAM
SHORT TERM...AJZ
LONG TERM...AJZ
AVIATION...ESS
MARINE...SAM






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