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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 160109
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
909 PM EDT TUE APR 15 2014

.SYNOPSIS...
AN EXCEPTIONALLY COLD AIRMASS FOR THIS TIME OF YEAR WILL QUICKLY
TAKE HOLD OF THE AREA BY LATE THIS EVENING. HIGH PRESSURE WILL BUILD
OVERHEAD DURING THE MIDDLE OF THE WEEK...THEN MOVE OFFSHORE LATE IN
THE WEEK. AN AREA OF LOW PRESSURE MAY AFFECT THE AREA DURING THE
FIRST HALF OF THE WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
THE COLD FRONT HAS MOVED OFF TO OUR EAST AND GUSTY NORTHWEST WINDS
TONIGHT WILL CONTINUE TO USHER IN UNUSUALLY COLD CONDITIONS
BEHIND THE BOUNDARY. PRECIPITATION NEAR AND EAST OF I-95 THIS
EVENING WILL GRADUALLY END FROM WEST TO EAST TOWARD MIDNIGHT.
THERE HAVE BEEN REPORTS OF SLEET AND SNOW AS COLDER AIR INTERACTS
WITH THE PRECIPITATION. ANY SNOW ACCUMULATION WILL BE CONFINED TO
GRASSY SURFACES...MAINLY NEAR THE MASON-DIXON LINE ACROSS THE
HIGHER ELEVATIONS. SNOWFALL ACCUMULATIONS AROUND AN INCH ARE
POSSIBLE ACROSS THESE AREAS. ELSEWHERE...LITTLE OR NO SNOW
ACCUMULATION IS EXPECTED BEFORE PRECIPITATION ENDS LATE THIS
EVENING.

DRIER AIR WILL WORK ITS WAY INTO THE AREA LATE TONIGHT AS HIGH
PRESSURE APPROACHES FROM THE WEST. HOWEVER...IT WILL TURN OUT
BLUSTERY AND VERY COLD FOR THIS TIME OF YEAR. A FREEZE WARNING
REMAINS IN EFFECT FOR LOCATIONS EAST OF THE BLUE RIDGE MOUNTAINS
WHERE THE GROWING SEASON HAS BEGUN. MIN TEMPS WILL RANGE FROM
UPPER TEENS ALONG THE ALLEGHENY FRONT...TO THE MID AND UPPER 20S
IN THE WASHINGTON AND BALTIMORE SUBURBS...TO THE LOWER 30S IN
DOWNTOWN WASHINGTON AND BALTIMORE AS WELL AS SOUTHERN MARYLAND.

HIGH PRESSURE WILL BUILD OVER THE REGION WEDNESDAY...BRINGING DRY
CONDITIONS ALONG WITH PLENTY OF SUNSHINE. HOWEVER...IT WILL BE
CHILLY FOR THIS TIME OF YEAR. MAX TEMPS WILL RANGE FROM NEAR 40 IN
THE MOUNTAINS TO THE UPPER 40S AND LOWER 50S ELSEWHERE. THE MAX
TEMP FORECASTS ARE AROUND 15 TO 20 DEGREES BELOW CLIMO.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE WEDNESDAY NIGHT ALONG WITH CLEAR SKIES/LIGHT WINDS
WILL PRODUCE A MORE TYPICAL RADIATIONAL COOLING NIGHT AND
THEREFORE TEMPERATURES ARE EXPECTED TO BOTTOM OUT AGAIN. FREEZE
WATCH HAS BEEN ISSUED EAST OF THE BLUE RIDGE INTO THURSDAY
MORNING.

HIGH PRESSURE CENTER MOVES OFF THE NORTHEAST COAST AND THEN WEDGES
DOWN THROUGH THE MID-ATLANTIC TO END THE WEEK. TEMPS MAY REBOUND
SOME...BUT WILL STILL BE BELOW AVERAGE THROUGH FRIDAY. CLOUDS LIKELY
INCREASE THURSDAY NIGHT INTO FRIDAY WITH A WEAK DISTURBANCE OFF THE
COAST AND ALSO AHEAD OF THE NEXT UPSTREAM SHORTWAVE TROUGH BUT FAVOR
A DRY FORECAST ATTM.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A COUPLE AREAS OF LOW PRESSURE WILL BRUSH PAST THE REGION FOR THE
FIRST PART OF THIS WEEKEND...WITH A CHANCE OF RAIN MAINLY DURING THE
DAY SATURDAY. THE MODELS HAVE MOST RECENTLY TRENDED DOWNWARD WITH
THE PROBABILITY OF RAIN AND WITH RAINFALL AMOUNTS AS A RESULT OF
ENERGY FROM THE NORTHERN AND SOUTHERN BRANCHES OF THE JET STREAM
REMAINING SPLIT INSTEAD OF PHASING. THIS LEAVES TO TWO WEAKER WAVES
OF LOW PRESSURE...ONE PASSING TO THE NORTHWEST ACROSS THE GREAT
LAKES AND THE OTHER MOVING OFFSHORE INTO THE ATLANTIC.

ANOTHER PUSH OF COOL AIR WILL ACCOMPANY HIGH PRESSURE MOVING DOWN
FROM CENTRAL CANADA FOR THE SECOND HALF OF THE WEEKEND...THOUGH NOT
NEARLY AS COLD OF AN AIRMASS AS IS EXPECTED DURING THE MIDDLE OF
THIS WEEK.

LOW PRESSURE WILL APPROACH THE AREA FROM THE WEST EARLY NEXT WEEK
BRINGING A CHANCE OF RAIN MONDAY INTO TUESDAY.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
ANY LEFTOVER PRECIPITATION WILL END BY LATE THIS EVENING. VFR
CONDITIONS ARE EXPECTED OVERNIGHT WITH GUSTY NORTHWEST WINDS. VFR
CONDITIONS WILL CONTINUE THROUGH WEDNESDAY. WINDS WILL GRADUALLY
SHIFT TO THE EAST-NORTHEAST AND DECREASE IN SPEED WEDNESDAY
AFTERNOON.

HIGH PRESSURE WED MOVES OFF THE COAST TOWARD THE END OF THE WEEK.
ONSHORE FLOW MAY LEAD TO FLIGHT RESTRICTIONS IN LOW CLOUDS THURSDAY
NIGHT INTO FRIDAY.

SUB-VFR POSSIBLE IN RAIN SATURDAY...THEN VFR SUNDAY. EASTERLY
WINDS 5 TO 10 KNOTS SATURDAY BECOME WEST OR NORTHWEST AROUND 10
KNOTS BY SUNDAY.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
WILL CONTINUE WITH A GALE WARNING FOR THE WATERS TONIGHT. THE
HIGHEST CONFIDENCE FOR GALE-FORCE WINDS WILL BE ACROSS THE MIDDLE
PORTION OF THE BAY AND LOWER TIDAL POTOMAC RIVER. ELSEWHERE...IT
WILL TURN OUT TO BE MORE MARGINAL WITH GUSTS AROUND 30 TO 35
KNOTS.

SCA CONTINUES FOR MUCH OF WEDNESDAY...BEFORE GRADIENT RELAXES LATER
IN THE AFTERNOON FOR DIMINISHING WINDS. NO SCA CONDITIONS ARE
EXPECTED WEDNESDAY NIGHT. MARGINAL SCA POSSIBLY AGAIN LATE
THURSDAY OR THURSDAY NIGHT WITH EAST WINDS.

SMALL CRAFT ADVISORY LEVEL WIND GUSTS ARE POSSIBLE FOR PARTS OF
THE WATERS SATURDAY NIGHT INTO SUNDAY IN A TIGHTENING PRESSURE
GRADIENT BETWEEN LOW PRESSURE DEPARTING TO THE NORTH AND HIGH
PRESSURE BUILDING IN FROM THE WEST.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --
GUSTY NORTHWEST WINDS TONIGHT INTO WEDNESDAY WILL CAUSE WATER
LEVELS TO RAPIDLY DECREASE. TIDAL BLOWOUT CONDITIONS ARE EXPECTED
WEDNESDAY WITH ANOMALIES AROUND 2 FEET BELOW NORMAL.
-- End Changed Discussion --

&&

.CLIMATE...
-- Changed Discussion --
JUST A DAY AFTER RECORD HIGH MINIMUM TEMPERATURES WERE OBSERVED...AN
EXCEPTIONALLY COLD AIRMASS FOR THIS TIME OF YEAR WILL APPROACH RECORD
MINIMUM TEMPERATURES EARLY WEDNESDAY MORNING. BELOW IS A TABLE OF
RECORD MINIMUM TEMPERATURES FOR APRIL 16 ALONG WITH THE FORECAST
MINIMUM TEMPERATURE FOR EARLY WEDNESDAY MORNING.

SITE...PREVIOUS RECORD...FORECAST MINIMUM...
DCA....29 F IN 1928......32 F...............
BWI....30 F IN 1962......29 F...............
IAD....28 F IN 1981......28 F...............
-- End Changed Discussion --

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FREEZE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
     MORNING FOR DCZ001.
     FREEZE WARNING FROM 3 AM TO 9 AM EDT WEDNESDAY FOR DCZ001.
MD...FREEZE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
     MORNING FOR MDZ004>007-009>011-013-014-016>018.
     FREEZE WARNING FROM 3 AM TO 9 AM EDT WEDNESDAY FOR MDZ011-013-
     014-016>018.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT WEDNESDAY FOR
     MDZ004>007-009-010.
VA...FREEZE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY
     MORNING FOR VAZ036>040-042-050>057-501-502.
     FREEZE WARNING FROM 3 AM TO 9 AM EDT WEDNESDAY FOR VAZ052>057.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT WEDNESDAY FOR
     VAZ036>040-042-050-051-501-502.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT WEDNESDAY FOR
     ANZ531>534-537-539>541-543.
     GALE WARNING UNTIL 6 AM EDT WEDNESDAY FOR ANZ530>543.
     SMALL CRAFT ADVISORY FROM 6 AM TO 2 PM EDT WEDNESDAY FOR
     ANZ530-535-536-538-542.

&&

$$
SYNOPSIS...DFH
NEAR TERM...BJL
SHORT TERM...BPP
LONG TERM...DFH
AVIATION...BJL/BPP/CAS
MARINE...BJL/BPP/CAS
TIDES/COASTAL FLOODING...BJL
CLIMATE...BJL