Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 012008
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
408 PM EDT FRI AUG 1 2014

.SYNOPSIS...
A FRONTAL BOUNDARY ALONG THE SOUTHEAST COAST WILL SLOWLY DRIFT
NORTH TOWARDS THE MID ATLANTIC COAST TONIGHT. THE FRONT THEN
STALLS ALONG THE COAST OR JUST INLAND OVER THE MID ATLANTIC
REGION...KEEPING UNSETTLED CONDITIONS IN PLACE THROUGH AT LEAST
MONDAY.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
A PERSISTENT UPPER LEVEL TROUGH WILL SIT OVER NERN U.S. FROM THE
MIDWEST THROUGH THE OH/TN VALLEYS AS PULSES OF SHORTWAVE ENERGY GET
PULLED INTO THE BASE OF THE TROUGH FROM THE GULF OF MEXICO AND THE
ATLANTIC. THESE SHORTWAVES WILL STREAM ACROSS THE COASTAL CAROLINAS
AND MID ATLANTIC REGION AND INTERACT WITH A SLOW-MOVING FRONTAL
BOUNDARY WHICH IS CURRENTLY DRAPED ALONG THE SE/CAROLINA COAST. THE
BOUNDARY DRIFTS NWD TWD THE MID ATLANTIC REGION AS WARM FRONT
TONIGHT BUT THEN THE GENERAL NWD MOVEMENT STALLS AND KEEPS THE
BOUNDARY STRADDLED ALONG THE COAST THROUGH AT LEAST MONDAY. THE END
RESULT WILL BE PERSISTENT RAIN SHOWERS AND CLOUDY CONDITIONS THROUGH
THE WEEKEND...WITH SLOW BUT STEADY IMPROVEMENT AS THE BOUNDARY
FINALLY GETS PULLED OFFSHORE BY TROPICAL STORM BERTHA SOMETIME
MONDAY NIGHT.

FOR THIS EVENING/TONIGHT...
AS MENTIONED ABOVE...PLENTY OF SHORTWAVE MOISTURE AND ENERGY WILL
TRAVERSE THE REGION (ESPECIALLY ALONG THE COAST) TONIGHT. RAIN
SHOWERS WILL INCREASE IN COVERAGE THROUGH THIS EVENING AS
ISENTROPIC LIFT AND DAYTIME HEATING ALOFT ENHANCE ATMOSPHERIC
LIFT. SHOWERS WILL BECOME MORE CONVECTIVE NEAR THE COAST INVOF THE
FRONTAL BOUNDARY AS IT LIFTS NORTH OF THE NC OUTER BANKS. AM
FINALLY STARTING TO SEE 6 HOUR PRECIP TOTALS OF 1.00 INCH OR MORE
ALONG THE PAMLICO SOUND IN ERN NC (NORTH OF THE PAMLICO RIVER BUT
SOUTH OF ALBEMARLE SOUND). WOULD PREFER TO SEE SIGNIFICANT
RAINFALL ACCUMULATIONS GREATER THAN 3.00 INCHES IN 1-3 HOURS
UPSTREAM IN ORDER TO CONSIDER A FLOOD WATCH WITH THE AFTN FORECAST
PACKAGE. PLUS GIVEN LOW RIVER LEVELS THROUGHOUT SE VA/NE NC AND
LACK OF SIGNIFICANT RAINFALL ACCUMULATIONS SO FAR TODAY...PREFER
TO HIGHLIGHT MINOR FLOODING POTENTIAL IN HWO AND IN HYDROLOGY
SECTION BELOW. THE POTENTIAL FOR FLOODING INCREASES GOING INTO
SATURDAY...MORE ON THIS IN THE SHORT TERM DISCUSSION BELOW. LOW
TEMPS OVERNIGHT MAY BE TRICKY DEPENDING ON 1) WHERE THE BOUNDARY
ENDS UP VS PROGGED MODEL SOLUTIONS AND 2) WHERE DRIER/LESS SHOWERY
AREAS OCCUR. HAVE LEFT ONGOING FORECAST INTACT WITH LOWS RANGING
FROM THE MID-UPPER 60S WELL INLAND TO UPPER 60S-LOWER 70S ALONG
THE COAST.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
FRONTAL BOUNDARY IS PROGGED TO STRADDLE THE COAST FROM THE
DELMARVA DOWN ALONG THE SE COAST. THE INTERACTION OF A STEADY
INFLUX OF MOISTURE AND SHORTWAVE ENERGY WITH THE FRONTAL BOUNDARY
WILL MAINTAIN HIGH PRECIP CHANCES...ONCE AGAIN WITH THE MAIN FOCUS
ALONG THE COAST AND ESPECIALLY NE NC/SE VA. MODEL SOUNDINGS FOR
KECG AND KORF ARE VERY MOIST...WITH SFC CAPES OF 700-1500 J/KG...
AND UNIDIRECTIONAL SW FLOW WHERE WINDS ARE VERY LIGHT BELOW
700-500MB (AT OR BELOW 20 KT). THIS IS A FAVORABLE SET-UP FOR
TRAINING PRECIPITATION ESPECIALLY ALONG THE STALLED BOUNDARY. THE
POTENTIAL FOR EMBEDDED THUNDERSTORMS ALSO INCREASES ON SATURDAY
NEAR THE COAST. IT IS VERY POSSIBLE THAT 3-6 HOUR PRECIP TOTALS
COULD BE UPWARDS OF 2.00 INCHES...ESPECIALLY IN CONVECTION. IF
THIS OCCURS ON TOP OF RAINFALL RECEIVED ON FRI/FRI NIGHT...THEN
THE POTENTIAL FOR A FLOOD WATCH BECOME INCREASINGLY LIKELY. WILL
NEED TO MONITOR TRENDS AND TOTALS FRI EVENING/OVERNIGHT TO
DETERMINE IF ADDITIONAL TOTALS ON SATURDAY WILL EXACERBATE MINOR
FLOODING POTENTIAL IN URBAN AREAS...LOW LYING AREAS...AREAS OF
POOR DRAINAGE...AND IN THE VICINITY OF SMALL STREAMS/CREEKS.
PLEASE REFER TO HYDROLOGY SECTION BELOW AND HWO FOR ADDITIONAL
DETAILS. ADDITIONAL RAINFALL AND THREAT FOR MINOR FLOODING
CONTINUES INTO SUNDAY AS OVERALL SYNOPTIC CONDITIONS REMAIN
UNCHANGED. PRECIPITATION COVERAGE STARTS TO DIMINISH FROM WEST TO
EAST ON MONDAY AS THE FRONT GETS PULLED OFFSHORE BY TROPICAL STORM
BERTHA.

HIGH TEMPERATURES WILL RUN ABOUT 5-10 DEGREES BELOW NORMAL DUE TO
PRECIP AND CLOUDY SKIES. HIGHS SAT MID-UPPER 70S...SUN AROUND 80...
MON LOW-MID 80S. LOWS WILL BE NEAR NORMAL WITH READINGS IN THE
MID 60S NW TO LOWER 70S SE.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE NEARLY STATIONARY FRONT AND ASSOCIATED PLUME OF ATLANTIC
MOISTURE SHOULD FINALLY NUDGE OFFSHORE MONDAY NIGHT AS A FINAL
WAVE OF LOW PRESSURE LIFTS NE ALONG THE BOUNDARY. THIS WAVE THEN
PULLS OFF THE COAST TUESDAY. 30-40% POPS WILL BE MAINTAINED OVER
SE PORTIONS IN CLOSER PROXIMITY TO THE SURFACE BOUNDARY. A BRIEF
DRY PERIOD IS EXPECTED TUESDAY NIGHT INTO EARLY WEDNESDAY AS
SHORTWAVE RIDGING PASSES OVERHEAD. A COLD FRONT THEN APPROACHES
FROM THE NW WEDNESDAY AND DROPS INTO THE AREA WEDNESDAY NIGHT.
THIS WILL BRING A CHC OF AFTERNOON/EVENING SHOWERS/TSTMS. THE
FRONT IS PROGGED TO DROP INTO NC THURSDAY. 20-30% POPS WILL BE
INCLUDED FOR SRN PORTIONS TO ACCOUNT FOR ANY UNCERTAINTY WITH
RESPECT TO THE FRONTAL LOCATION. THE FRONT SHOULD EVENTUALLY LIFT
BACK N LATER IN THE WEEK...BUT CONFIDENCE WITH RESPECT TO TIMING
AND LOCATION IS LOW...SO MINIMAL POPS WILL BE CONTINUED. HIGHS
TUESDAY SHOULD AVERAGE IN THE UPPER 80S...WITH UPPER 80S/
AROUND 90 WEDNESDAY AHEAD OF THE FRONT. HIGHS SHOULD DROP BACK
INTO THE MID/UPPER 80S THURSDAY AND FRIDAY BEHIND THE FRONT. LOW
TEMPERATURES SHOULD AVERAGE FROM THE MID 60S TO LOW 70S.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
SHOWERS WITH MODERATE/OCCASIONALLY HEAVY RAIN NOW PUSHING N INTO
THE REGION...SHOULD AFFECT MAINLY KECG THROUGH 00Z...WITH GENLY
ONLY LIGHT/MODERATE RAIN ELSEWHERE. HAVE INCLUDED A TEMPO GROUP
FOR IFR VSBYS AT KECG...MVFR ELSEWHERE. CIGS CONTINUE TO LOWER
LATER TONIGHT AND COULD SEE SEVERAL HRS WHERE THEY DROP TO 1-2 K
FT OVERNIGHT...WITH KRIC/KSBY HAVING HIGHEST CHANCE FOR IFR CIGS/
BELOW 1 KFT. SOME BRIEF EMBEDDED TSTMS POSSIBLE AS WELL...MOST
LIKELY AT KECG/KORF/KPHF...BUT PROBABILITY TOO LOW TO INCLUDE IN
TAFS.

OUTLOOK...THREAT FOR SHOWERS/TSTMS PERSIST SAT/SUN AS MOISTURE
WITH STALLED BOUNDARY ALONG/JUST INLAND FROM THE COAST. PERIODIC
FLIGHT RESTRICTIONS WILL BE POSSIBLE IN HEAVIER SHOWERS/TSTMS BOTH
DAYS. OVERALL COVERAGE OF PRECIP WILL GRADUALLY DIMINISH MON/MON
NIGHT.

&&

.MARINE...
AN INVERTED TROUGH WILL REMAIN OFF THE COAST TONIGHT AND STEADILY
DRIFT INLAND THROUGH THE WEEKEND. NO FLAGS ARE EXPECTED AS WIND
SPEEDS SHOULD REMAIN AOB 15KT (DIRECTION AVERAGING E/SE) AND
SEAS/WAVES SHOULD REMAIN BELOW 5FT/4FT. NEVERTHELESS...PERSISTENT
ONSHORE FLOW SHOULD BUILD SEAS TO AROUND 3FT...WITH OCCASIONAL 4FT
SEAS OUT NEAR 20NM. WAVES IN THE MOUTH OF THE BAY SHOULD BUILD TO
2-3FT...WITH 1-2FT ELSEWHERE IN THE BAY. THE SYSTEM PUSHES
OFFSHORE EARLY NEXT WEEK AS HIGH PRESSURE RETURNS TO THE REGION. A
COLD FRONT APPROACHES FROM THE NW DURING THE MIDDLE OF NEXT WEEK.
OVERALL SUB-SCA CONDITIONS ARE EXPECTED TO PREVAIL DURING THE
EARLY TO MIDDLE PORTION OF NEXT WEEK. HOWEVER...SOME LONG PERIOD
SWELL COULD ENCROACH THE AREA DEPENDING ON THE STRENGTH/TRACK OF
TS BERTHA. CURRENT 01/12Z WAVEWATCH GUIDANCE BRINGS 3-4FT SWELL
OUT NEAR 20NM TUESDAY/WEDNESDAY OF NEXT WEEK.

&&

.HYDROLOGY...
PERSISTENT RAINFALL ALONG A SLOW-MOVING FRONTAL BOUNDARY WILL
BRING STEADILY ACCUMULATING PRECIPITATION TO THE REGION THE REST
OF TODAY THROUGH AT LEAST MONDAY...WITH BEST ACCUMULATIONS FOCUSED
OVER NE NC AND SE VA. ACROSS THE AFOREMENTIONED SOUTHEAST AREAS...
STORM TOTAL PRECIPITATION AMOUNTS OF 2.50 TO 3.50 INCHES (LOCALLY
UP TO 4.00 INCHES) ARE ANTICIPATED OVER THE NEXT 48-72 HOURS. THIS
MAY POTENTIALLY CAUSE MINOR FLOODING OF URBAN AREAS...AREAS OF
POOR DRAINAGE...LOW LYING AREAS...AND TO RISES OF SMALL
STREAMS/CREEKS. A FLOOD WATCH MAY BE NEEDED LATER THIS EVENING OR
OVERNIGHT DEPENDING ON UPSTREAM PRECIPITATION TRENDS. WILL
CONTINUE TO HIGHLIGHT FLOODING POTENTIAL IN THE HWO (WBCHWOAKQ).

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR
     NCZ102.
VA...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR
     VAZ098.
MARINE...NONE.

&&

$$
SYNOPSIS...BMD
NEAR TERM...BMD
SHORT TERM...BMD
LONG TERM...AJZ
AVIATION...LKB
MARINE...AJZ
HYDROLOGY...BMD










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