Area Forecast Discussion
Issued by NWS Sterling, VA

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633
FXUS61 KLWX 052006
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
406 PM EDT THU MAY 5 2016

.SYNOPSIS...
LOW PRESSURE IMPACTS THE REGION TO END THE WEEK WITH A COLD FRONT
SWINGING THROUGH SUNDAY. HIGH PRESSURE BRIEFLY BUILDS IN...WITH A
WARM FRONT LIFTING NORTH FIRST HALF OF NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
WATER VAPOR IMAGERY EARLY THIS AFTN SHOWING CLOSED UPPER LVL LOW
HAS SLIDE SLIGHTLY SOUTH INTO TN...WITH ENERGY SWINGING AROUND THE
NORTHEAST FRINGE OF IT. RAIN ON GOING MAINLY SOUTH OF THE CWA
WHERE BEST CONVERGENCE HAS ALIGNED WITH THIS ENERGY. COULD SEE
SCT RAIN SHOWERS OVER THE SW CORNER AND ISO SHOWERS OVER THE
REMAINDER OF THE CWA THRU THE AFTN INTO THIS EVENING.
OVERALL...LOOKS LIKE MINIMAL FLOOD THREAT THRU THE DAYLIGHT HOURS
TODAY.

HEADING INTO TONIGHT AND INTO FRIDAY...AFOREMENTIONED UPPER LVL
LOW PIVOTS TO THE SOUTH AND THEN EAST...BCMG NEARLY STATIONARY
OVER THE DELMARVA REGION FOR MOST OF FRI INTO SATURDAY. A
SHORTWAVE CURRENTLY OVER WESTERN CANADA WILL BE NEEDED TO
EVENTUALLY PUSH THIS NEARLY STALLED CLOSED LOW OUT LATER THIS
WEEKEND. BEFORE HAND HOWEVER...EXPECTING AN INCREASE IN COVERAGE
AND INTENSITY OF RAIN SHOWERS TONIGHT ACROSS THE ENTIRE
CWA...LASTING THRU A GOOD PORTION OF FRIDAY AS THE MAIN FORCING
WITH THE UPPER LVL LOW SWINGS AROUND THE EASTERN PERIPHERY RIGHT
THRU THE MID- ATLANTIC. MEANWHILE AT THE SFC...SFC LOW PUSHING OFF
THE CAROLINA COAST WILL MOVE TO THE NORTHEAST...WITH A SECONDARY
LOW FORMING JUST OFF THE SE VA COAST. CLOUDS AND NLY FLOW WILL
KEEP TEMPS ON THE COOLER SIDE WITH TEMPS BELOW NORMAL.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
THE UPPER LVL LOW REMAINS POSITIONED OVER THE REGION FOR THE TIME
PERIOD...WITH THE SFC LOW HAVING BACKED OVER THE DELMARVA
REGION...AND REMAINING NEARLY STATIONARY AS WELL. THIS WILL KEEP
THE CHC FOR PCPN IN THE FORECAST THRU SATURDAY...THOUGH WITH THE
BETTER FORCING WITH THE UPPER LVL LOW TO THE NE OF THE
CWA...HEAVIER RAIN THREAT WILL BE ON THE LOWER END.

SHORTWAVE DIGGING SOUTH OVER THE GREAT LAKES REGION SAT NIGHT WILL
BRING AN ASSOCIATED SFC COLD FRONT THRU THE REGION...WHICH WILL
CONTINUE TO BRING THE CHC OF RAIN SHOWERS TO THE AREA AS WELL AS
FINALLY BEING ABLE TO NUDGE THE CLOSED LOW AND SFC LOW OUT OF THE
MID-ATLANTIC.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
COLD FRONT WILL MOVE ACROSS THE REGION SUN MORNING WITH A CHANCE
OF RAIN SHOWERS. THE FRONT WILL STALL TO OUR SOUTH OVER THE
CAROLINAS AS DRY CONDITIONS BUILD OVER OUR REGION LATER ON SUN AND
INTO MON. THE FRONT WILL LIFT AS A WARM FRONT MON NIGHT INTO TUE
BRINGING BACK THE CHANCE OF SHOWERS. GUIDANCE DIFFERS FOR TUES AND
INTO WED AS OF PRECIP AND POSITION OF A SFC LOW THAT WILL MOVE E
OR NE FROM THE PLAINS. ANOTHER COLD FRONT EXPECTED ON THU.

HIGH TEMPS WILL BE IN THE 70S AND LOW 80S AND LOW TEMPS INCREASING
FROM THE 40S AND 50S INTO THE UPR 50S AND LOW 60S.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
CONDITIONS MAINLY MVFR AT ALL THE TERMINALS THIS AFTN. MODEL
GUIDANCE HINTS AT SLIGHT IMPROVEMENT LATER THIS AFTN BUT
CONFIDENCE IS LOW OUTSIDE OF KMRB OF THIS OCCURRING MORE THAN IS
ALREADY NOTED IN TAFS. BY TONIGHT...INCREASED COVERAGE AND
INTENSITY IN THE RAIN WILL KEEP CONDITIONS MAINLY IFR. WINDS NE
BCMG N ON FRIDAY...10 KTS OR LESS. SUB-VFR CONDITIONS EXPECTED
THRU SAT TO ACCOUNT FOR ON/OFF RAIN SHOWERS AND STRATUS.

SUB-VFR CONDITIONS POSSIBLE EARLY ON SUN AS COLD FRONT MOVES
THROUGH. VFR CONDITIONS EXPECTED LATER ON SUN AND INTO MON. SUB-
VFR PSBL MON NIGHT INTO TUES AS WARM FRONT BRINGS BACK CHANCE OF
SHOWERS TO THE REGION.

&&

.MARINE...
OCNL GUSTS INTO THE UPPER TEENS LATE THIS AFTN...SO HAVE GONE WITH
A SCA FOR JUST THE SOUTHERN EXTENT OF OUR FORECASTED WATERS THRU
THE EVENING. SUB-SCA ON ALL WATERS FRI-SAT. INCRSG WINDS AHEAD OF
THE APPROACHING COLD FRONT SAT NIGHT COULD BRING SCA GUSTS BACK IN
AT LEAST ON THE CHESAPEAKE BAY.

SCA CONDITIONS EXPECTED SUN... THEN WINDS WILL DECREASE...EXPECTING
SUB-SCA CONDITIONS FOR MON AND TUE.

&&

.TIDES/COASTAL FLOODING...
MINOR FLOODING IS OCCURRING DUE TO PERSISTENT ONSHORE NE FLOW.
COASTAL FLOOD ADVISORY IN PLACE ALONG THE WESTERN SIDE OF
CHESAPEAKE BAY SOUTH OF BALTIMORE THRU EARLY FRIDAY MORNING TO
ACCOUNT FOR MINOR LVLS BEING REACHED AROUND THE TIME OF HIGH TIDE.
IN ADDITION...AN ADVISORY IS IN PLACE FOR DC/ALEXANDRIA FOR THE
EVENING TIDE CYCLE.

AFTER RECEIVING SHIFT BRIEFING AND LOOKING AT LATEST TRENDS...
BELIEVE ANNAPOLIS IS TOO CLOSE TO MINOR THRESHOLD CRITERIA TO SIT
ON THE SIDELINES. HAVE BUMPED UP THE START TIME TO COVER THE LATE
AFTN TIDE CYCLE FOR ANNE ARUNDEL CNTY.

ALSO OF NOTE IS STRAITS POINT WHICH SOME GUIDANCE WANTS TO PUSH
TO MODERATE LVL FOR TONIGHT. HAVE STAYED MORE CONSERVATIVE WITH
THE FORECAST FOR THE TIME BEING...KEEPING JUST BELOW BUT WILL
CONTINUE TO MONITOR.

MINOR FLOODING IS EXPECTED ON FRIDAY WITH THE INCREASED ONSHORE
FLOW. THE FLOODING THREAT MAY EXTEND INTO SAT ON THE WESTERN
CHESAPEAKE BAY DEPENDING ON HOW QUICKLY THE WINDS SHIFT/WEAKEN.
ANTICIPATE ADDTL CHGS TO THE ADVISORY LINEUP THIS EVENING...WHICH
MAY FEATURE AN UPGRADE OR TWO TO WARNING.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR DCZ001.
MD...COASTAL FLOOD ADVISORY UNTIL 6 AM EDT FRIDAY FOR MDZ017-018.
     COASTAL FLOOD ADVISORY UNTIL 9 AM EDT FRIDAY FOR MDZ014.
VA...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR VAZ054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EDT FRIDAY FOR ANZ534-543.

&&

$$
SYNOPSIS...SEARS/IMR
NEAR TERM...SEARS
SHORT TERM...SEARS
LONG TERM...IMR
AVIATION...SEARS/IMR
MARINE...SEARS/IMR
TIDES/COASTAL FLOODING...SEARS/HTS



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