269
FXUS61 KAKQ 241957
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
357 PM EDT FRI MAY 24 2013
SYNOPSIS
COLD FRONT WILL CONTINUE TO PUSH OFFSHORE TONIGHT AS HIGH PRESSURE
BUILDS OVER THE OHIO VALLEY. HIGH PRESSURE WILL CONTINUE TO BUILD
INTO THE MID ATLANTIC THIS WEEKEND...RESULTING IN DRY AND COOL
CONDITIONS. A WARMING TREND WILL BEGIN MEMORIAL DAY THROUGH NEXT
WEEK.
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
LATEST WATER VAPOR IMAGERY SHOWS DEEP UPPER TROUGH (500MB HEIGHTS
-2 STD DEV) DIGGING OVER THE ERN CONUS. AT THE SFC...COLD FRONT
HAS PUSHED OFFSHORE WITH HIGH PRESSURE BUILDING OVER THE GREAT
LAKES REGION. NARROW LINE OF SHOWERS WILL CLEAR THE COAST THE NEXT
FEW HOURS (BEFORE 5PM EDT). UPPER TROUGH AXIS WILL LOCATE ALONG
THE COAST EARLY THIS EVENING...EFFECTIVELY BRINGING AN END TO THE
PRECIP. NW WINDS 10 TO 15 MPH WITH GUSTS UP TO 25 MPH (STRONGER
NEAR THE COAST) WILL SUBSIDE LATE AFTERNOON AS SKIES CLEAR WEST TO
EAST. COLD TONIGHT AS LIGHT WINDS AND CLEARING SKIES ALLOW FOR
GOOD RADIATIONAL COOLING. TEMPS FORECAST TO FALL INTO THE LOW/MID
40S.
SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/
UPPER PATTERN DURING THE SHORT TERM WILL BE CHARACTERIZED BY A
TROUGH IN BOTH THE WEST AND EAST WITH RIDGING OVER THE CNTRL
CONUS. UPPER CLOSED LOW WILL DEVELOP OFF THE MID ATLANTIC COAST
SAT...SLOWLY LIFTING UP THE NE COAST SAT-SUN DUE TO BLOCKING OVER
THE WRN ATLANTIC. CONFLUENCE ALOFT WILL USHER IN COOL SFC HIGH
PRESSURE OVER THE WEEKEND. THE RESULTANT DEEP LAYER NWLY FLOW WILL
RESULT IN DRY...BUT COOL CONDITIONS THROUGH THE MEMORIAL DAY
WEEKEND. 850MB TEMPS WILL FALL AS LOW AS 2 STD DEV BELOW NORMAL
THIS WEEKEND...WITH TEMPS GENERALLY UPPER 60S/LOW 70S SAT AND LOW
70S SUN (-1 STD DEV). TEMPS WILL FALL INTO THE MID/UPPER 40S SAT
NIGHT AND UPPER 40S/LOW 50S SUN NIGHT.
MEANWHILE...STALLED FRONTAL BOUNDARY OVER THE NRN GULF WILL BEGIN
TO LIFT NWD LATE SUNDAY AND MONDAY...LOCATING OVER THE DEEP SOUTH
MONDAY MORNING...EXTENDING NWWD INTO THE PLAINS. UPPER RIDGE WILL
FINALLY PROGRESS EWD MON AS THE UPPER LOW OVER SE CANADA LIFTS. AS
A RESULT...A WARMING TREND WILL COMMENCE MON. AS THE RIDGE
PROGRESSES EWD...A WARM/MOIST AIRMASS WILL INTERACT WITH THE
BOUNDARY TO PRODUCE SHOWERS AND THUNDERSTORMS OVER THE MIDWEST
INTO THE OH VALLEY MONDAY AFTERNOON. ACTIVITY THEN EXPECTED TO
FORM INTO A MESOSCALE CONVECTIVE SYSTEM. MCS WILL ROUND THE
RIDGE...BUT WILL DIE OUT BEFORE REACHING THE MID-ATLANTIC.
BOUNDARY WILL CONTINUE TO LIFT NWD MONDAY NIGHT...WITH BETTER
CHANCE FOR SHOWERS AND THUNDERSTORMS IN THE EXTENDED PERIOD.
LONG TERM /TUESDAY THROUGH FRIDAY/
HV AGAIN GONE CLOSE TO A ECMWF/HPC(WPC) BLEND FOR THE MIDWEEK TIME
FRAME. HV ALLOWED FOR SOME SHRAS/ISO T LATER TUESDAY AS WARM FRONT
LIFTS NORTH ACROSS THE AREA, WITH BEST CHANCES ACROSS AREAS NORTH OF
FVX/RIC/WAL LINE.
THE FRONT SHUNTS NORTH OF THE AREA FOR THE MID TO LATTER PART OF THE
WEEK. MEANWHILE, MID-UPPER LEVEL RIDGING REBUILDS ACROSS THE EASTERN
HALF OF THE CONUS AS SFC HIGH SLIDES OFF THE MID-ATLANTIC COAST.
RESULTANT BERMUDA HIGH/"SUMMERLIKE" SETUP WILL ALLOW FOR INCREASING
TEMPS (AND HUMIDITY VALUES) FOR THE MID TO LATTER PART OF NEXT WEEK.
RAINFALL OPPORTUNITIES DURING THIS PERIOD WILL PRIMARILY BE
DIURNALLY DRIVEN, WITH LITTLE MORE THAN PARTLY CLOUDY AND
INCREASINGLY MUGGY CONDITIONS BY NIGHT.
AVIATION /20Z FRIDAY THROUGH WEDNESDAY/
POTENT MID/UPR LVL TROUGH HAS LED TO WIDESPREAD SHRA ACRS THE AREA
OVER THE PAST FEW HRS. WINDS HAVE SHIFTED TO THE NNW AT ALL SITES
AS OF 1730Z. IMPROVING SKY CONDITIONS AT KRIC WITH CIGS LIFTING
ABOVE 3 K FT...BUT FARTHER EAST CAN EXPECT MVFR CIGS AND/OR VSBYS/POCKETS
OF IFR THROUGH 20Z WITH SHRA AND GUSTY N/NW WINDS GUSTING TO 20 TO 30
KT THROUGH 00Z. WINDSPEEDS SUBSIDE TNGT...ALTHOUGH REMAIN GUSTY TO 20
KT OR SO CLOSER TO THE COAST. VFR/DRY CONDITIONS ON SAT...BUT ALL
SITES CAN EXPECT GUSTY NW FLOW..TO 20-25 KT (25-30 KT AT KSBY).
GENLY SKC WITH LIGHTER WINDS SAT NIGHT-SUN.
GENLY DRY/VFR THROUGH MONDAY WITH INCREASING MOISTURE LATER MON-
TUE AS A WARM FRONT BEGINS TO AFFECT THE AREA. THIS WOULD BE NEXT
CHANCE FOR MORE SIGNIFICANT CIG/VSBY RESTRICTIONS.
MARINE
LATEST OBS REFLECT NW FLOW GENERALLY 20-25KT WITH GUSTS TO ~30 KT IN
MOD CAA THIS AFTN. MSAS 3-HR PRESSURE CHANGE IS NOTING ~2-3 MB
PRESSURE RISES OVER THE MARINE AREA BEHIND COLD FRONT WHICH HAS
SHUNTED OFFSHORE THIS AFTN. HV GENERALLY NOTED GUSTS RUNNING JUST
SLIGHTLY AHEAD OF GUIDANCE, HELPED IN PART BY SCT SHRAS ALLOWING
STRONGER WINDS ALOFT TO MIX DOWN TO THE SFC. HV GONE AHEAD WITH GALE
WARNING OVER NORTHERN BAY ZONES AND FAR NORTHERN COASTAL ZONES. WIND
GUSTS ARE VERY CLOSE TO GALE IN THESE AREAS ATTM...AND WITH
STRONGEST SURGE OF CAA STILL A FEW HRS OFF, EXPECT PREDOMINATE GUSTS
TO GALE FOR A FEW HRS BETWEEN 00Z/8P AND 10Z/6A. HV RUN HEADLINE
THROUGH 15Z/11A FOR NOW, WITH THE IDEA THAT OVERNIGHT CREW KEEP AN
EYE ON OBS AND EXPIRE EARLY AS NEEDED.
SEAS WILL RUN ON THE ORDER OF 5-8 FT ON THE COASTAL WATERS...WAVES
~2 FT ON THE SOUND, 2-3 FT ON THE RIVERS, 3-5 IN THE LOWER CHES BAY.
PERIOD OF SCA FLAGS WILL BE RE-ISSUED AS SOON AS GALES ARE EXPIRED
AS DEVELOPING LOW PRESSURE OFF NJ/SRN NEW ENG COAST SLOWLY LIFTS TO
THE NE INTO SUN...RESULTING IN ONLY GRADUAL IMPROVEMENT (SCA PER
WAVEWATCH POTENTIALLY TO LINGER OVR THE NRN OCN WTRS INTO LATE SAT).
SCA FLAGS DROP OFF OVER ALL BUT COASTAL AREAS SAT NIGHT, EXTENDING
INTO ERY SUNDAY OVER NRN COASTAL ZONES.
FAR MORE FAVORABLE BOATING CONDITIONS EXPECTED FOR THE LATTER HALF
OF THE HOLIDAY WEEKEND AS HIGH PRESSURE BUILDS IN FROM THE NW. WINDS
AND SEAS WILL GRADUALLY DIMINISH THROUGH THIS PD WITH W WINDS AOB 15
KT.
AKQ WATCHES/WARNINGS/ADVISORIES
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ633-
635>638.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT SATURDAY NIGHT FOR
ANZ632-634-654-656-658.
GALE WARNING UNTIL 11 AM EDT SATURDAY FOR ANZ630-631-650-652.
SYNOPSIS...SAM
NEAR TERM...SAM
SHORT TERM...SAM
LONG TERM...MAM
AVIATION...LKB
MARINE...MAM
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