Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 180149 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 849 PM EST MON NOV 17 2014 .SYNOPSIS... A STRONG COLD FRONT WILL CONTINUE TO PASS THROUGH THE AREA THIS AFTERNOON AND EVENING. ARCTIC HIGH PRESSURE WILL BUILD TOWARD THE REGION BEHIND THIS SYSTEM TUESDAY THROUGH TUESDAY NIGHT. A REINFORCING COLD FRONT WILL APPROACH THE AREA WEDNESDAY AND WEDNESDAY NIGHT BEFORE PASSING THROUGH THURSDAY. AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE AREA FRIDAY AND HIGH PRESSURE WILL RETURN FOR SATURDAY. && .NEAR TERM /THROUGH TUESDAY/...
-- Changed Discussion --
AS OF MID EVENING...COLD FRONT HAS PUSHED EAST OF THE CWA. SOME DRIZZLE REMAINS NEAR THE BAY BUT SHOULD END SHORTLY AS DRIER AIR IS WHISKED IN /15F DEW POINT GRADIENT ALONG THE I-95 CORRIDOR/. IN THE IMMEDIATE POST FRONTAL ENVIRONMENT THE W TO NW WINDS ARE SOMEWHAT GUSTY TO AROUND 20 KT. SOME DISAGREEMENT IN THE GUIDANCE ON TO WHETHER THESE DIMINISH OVERNIGHT OR CONTINUE IN THE STRONG CAA. WILL ALLOW THE SPEEDS TO EASE A BIT IN THE FORECAST BUT SOME GUSTINESS WILL CONTINUE. LOW CLOUDS ARE SCOURING OUT...BUT SOME STRATOCUMULUS MAY LINGER IN THE LEE OF THE MOUNTAINS...PARTICULARLY WHERE THE BARRIER IS LOWER OVER THE NORTHERN CWA. ON THE WESTWARD FACING SLOPES...SNOW SHOWERS WILL CONTINUE OVERNIGHT. ACCUMULATIONS WILL BE LIGHT...BUT SNOW WILL BE EASILY PRODUCED AS THE LOW LEVEL MOISTURE INTERSECTS THE DENDRITIC GROWTH ZONE. THE TEMPERATURE CURVE IS ON TRACK SO FAR AS THE ANOMALOUSLY COLD AIR MASS SURGES INTO THE AREA...SO MINIMAL CHANGES FOR OVERNIGHT LOWS...WHICH WILL BE IN THE 20S FOR MOST...WITH TEENS IN THE HIGHER ELEVATIONS AND AROUND 30 IN URBAN AND COASTAL AREAS. WIND CHILLS WILL DROP INTO THE TEENS OUTSIDE OF URBAN AREAS...WITH SINGLE DIGITS IN THE HIGHER ELEVATIONS. HIGH PRESSURE BUILDS IN THROUGH TUESDAY...SO OTHER THAN THE HIGH ELEVATION SNOW SHOWERS...DRY WEATHER IN PLACE. HOWEVER...WINDS WILL RAMP UP QUICKLY BY 12Z AND LAST THROUGH THE DAY. MODEL GUIDANCE VARIES ON EXACTLY HOW STRONG...WITH THE 12Z GFS SOUNDINGS SHOWING THE POTENTIAL OF 30-35 KTS MIXING DOWN AT SPOTS. SIDED WITH A MORE CONSERVATIVE NAM FOR GUSTS...KEEPING THEM MAINLY 25 KTS OR LESS. ISOLATED AREAS ABOVE 3 KFT WILL SEE THE STRONGEST GUSTS...BUT CONFIDENCE EVEN THERE IS NOT GREAT ENOUGH TO WARRANT THE ISSUANCE OF A WIND ADVISORY. WITH THE LACK OF CONFIDENCE...HAVE REMOVED THIS MENTION AS WELL FROM THE HWO. AS THE HIGH BUILDS IN...STRONG CAA QUICKLY MOVES IN...WITH 850MB TEMPS DROPPING TO AROUND -15 DEGREES BELOW ZERO BY 12Z TUES. LITTLE VARIATION IN TEMPS FOR THE HIGHS ON TUESDAY...AS MOST PLACES STRUGGLE TO REACH EVEN 30. AGAIN...WITH THE GUSTY WINDS...WIND CHILLS IN THE SINGLE DIGITS TO TEENS WILL CONTINUE.
-- End Changed Discussion --
&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... THE UPPER LOW WILL MOVE ACROSS NEW ENGLAND TUESDAY NIGHT WHILE HIGH PRESSURE MOVES INTO THE SE US TUESDAY NIGHT. WESTERLY WINDS WILL CONTINUE OVERNIGHT BUT TAPER OFF TO 5-10MPH. UPSLOPE SNOW SHOWERS WILL ALSO TAPER OFF BY WEDNESDAY MORNING ALONG THE WESTERN SLOPES. NO ACCUMULATION IS EXPECTED TUESDAY NIGHT. COLD CONDITIONS WILL CONTINUE ACROSS THE MID-ATLANTIC. FCST MIN TEMPS WILL RANGE FROM THE TEENS ALONG THE HIGHER ELEVATIONS TO THE LOW TO MID 20S ACROSS THE I-95 CORRIDOR. LITTLE TO NO RIDGING WILL TAKE PLACE BEFORE THE NEXT UPPER LEVEL TROUGH MOVES INTO THE NRN PLAINS WEDNESDAY. HIGH PRESSURE WILL MOVE OFF THE SE US COAST AND WINDS WILL BECOME SWLY THROUGH THE COLUMN. AN UPPER LEVEL ENERGY AHEAD OF THE TROUGH WILL APPROACH THE HIGHLANDS WEDNESDAY. CLOUDS WILL INCREASE FROM WEST TO EAST ACROSS THE REGION. SNOW SHOWERS ARE POSSIBLE ACROSS THE WESTERN SLOPES OF THE ALLEGHENY FRONT. ELSEWHERE...LITTLE MOISTURE IS EXPECTED WITH THIS UPPER LEVEL FEATURE AND NO PRECIPITATION IS EXPECTED EAST OF THE APPALACHIANS THROUGH WEDNESDAY NIGHT. && .LONG TERM /THURSDAY THROUGH MONDAY/... A DRY COLD FRONT WILL PUSH ACROSS THE REGION THURSDAY...FOLLOWED BY A BUILDING RIDGE OF HIGH PRESSURE THURSDAY NIGHT THROUGH FRIDAY NIGHT. ASIDE FROM SOME UPSLOPE SNOW SHOWERS IN THE POTOMAC HIGHLANDS THURSDAY AND THURSDAY EVENING...THE REMAINDER OF THE REGION WILL REMAIN DRY. TEMPERATURES WILL STAY BELOW NORMAL THROUGH FRIDAY NIGHT. AS THE HIGH SHIFTS TO THE COAST AND THEN OFFSHORE SATURDAY AND SATURDAY NIGHT...WINDS WILL SHIFT AROUND TO THE SOUTH AHEAD OF A STORM SYSTEM AND COLD FRONT MOVING ACROSS THE WESTERN OHIO VALLEY. TEMPERATURES WILL MODIFY SATURDAY NIGHT THROUGH MONDAY. DRY CONDITIONS SATURDAY WITH A SLIGHT CHANCE OF SOME WARM-FRONTAL PERIODS OF LIGHT SNOW SATURDAY NIGHT IN THE POTOMAC HIGHLANDS AND CENTRAL SHENANDOAH VALLEY. SOME LIGHT RAIN WILL MOVE IN AS TEMPERATURES MODIFY SUNDAY THROUGH MONDAY. COLDER SPOTS DURING THE DAY SUNDAY COULD ENCOUNTER A MIX OF RAIN OR SNOW. SOME UNCERTAINTIES AS TO THOSE LOCATIONS AT THIS TIME. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
WINDS HAVE TURNED W TO NW BEHIND A DEPARTING COLD FRONT AND CIGS WILL CONTINUE TO LIFT/SCATTER OUT THROUGH THE EVENING. A FEW WIND GUSTS IN THE 15-20 KT RANGE WILL BE POSSIBLE THIS EVENING. WILL MONITOR TO SEE IF THESE GUSTS COULD CONTINUE THROUGHOUT THE NIGHT BUT THE CURRENT THINKING IS THE GUSTS WILL BECOME LESS PREVALENT. CONDITIONS WILL REMAIN VFR TUESDAY AND TUESDAY NIGHT...WITH A FEW STRATOCUMULUS CLOUDS AT MOST. CONCERN WILL BE WINDS...WHICH WILL INCREASE AROUND 14Z GIVE OR TAKE AN HOUR. GUSTS WILL LIKELY RANGE FROM 20-25 KT AND POSSIBLY A LITTLE HIGHER THROUGHOUT THE DAY...WITH HIGH CONFIDENCE OF A WNW DIRECTION. THE WIND GUSTS WILL SUBSIDE WITH SUNSET TUESDAY EVENING. VFR CONDITIONS ARE EXPECTED WEDNESDAY AND WEDNESDAY NIGHT. W-SW WINDS 5-10 KT ARE EXPECTED WEDNESDAY AND WEDNESDAY NIGHT. VFR CONDITIONS THURSDAY THROUGH FRIDAY. WINDS SOUTHWEST BECOMING NORTHWEST AT 10 TO 15 KNOTS GUSTING 20 TO 25 KNOTS THURSDAY AND THURSDAY NIGHT. SOME GUSTS TO 20 KNOTS MAY OCCUR FRIDAY AFTERNOON.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SCA REMAINS IN EFFECT FOR ALL WATERS THROUGH TONIGHT. GUSTS ABOVE 18KT WILL BE PERIODIC OVERNIGHT...BUT WINDS WILL INCREASE MARKEDLY AFTER DAYBREAK TUESDAY. FOR TUESDAY AFTERNOON...WINDS WILL APPROACH GALES...AND ALTHOUGH MARGINAL...35 KT OF WIND EXIST A FEW THOUSAND FEET ABOVE SEA LEVEL AND COULD EASILY MIX DOWN. A GALE WARNING WILL BE IN EFFECT FOR THE AREA WITH THE HIGHEST CONFIDENCE OF MEETING CRITERION...FOR THE CHESAPEAKE BAY...FROM 12-21Z. HELD OFF ON THE POTOMAC RIVER FOR NOW WITH THE THINKING THEY WILL STAY 30 KTS OR LESS. ONCE THE GALE COMES DOWN TOMORROW AFTN...SCA CONTINUES THROUGH MIDNIGHT TOMORROW NIGHT...WITH WINDS SUBSIDING AS THE HIGH PRESSURE TAKES HOLD OVER THE REGION. SMALL CRAFT ADVISORIES ARE POSSIBLE THURSDAY AND THURSDAY EVENING THEN AGAIN FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. GUSTS 20 TO 25 KNOTS THURSDAY.
-- End Changed Discussion --
&& .CLIMATE... BITTERLY COLD AIR FOR THIS TIME OF YEAR WILL MOVE OVERHEAD TUESDAY AND WEDNESDAY. TEMPERATURES WILL BE BETWEEN 10 AND 20 DEGREES BELOW NORMAL. IN FACT...TEMPERATURES TUESDAY AND WEDNESDAY WOULD BE SEVERAL DEGREES BELOW NORMAL IN JANUARY. BELOW IS A LIST OF RECORD DAILY MINIMUM AND RECORD DAILY LOW MAXIMUM TEMPERATURES FOR THE DATES OF NOVEMBER 18TH (TUESDAY) AND 19TH (WEDNESDAY). SITE 11/18 MIN 11/18 LOW MAX 11/19 MIN 11/19 LOW MAX DCA 21 (1959) 30 (1924) 18 (1891) 33 (1880) BWI 20 (1959) 31 (1959) 20 (1936) 35 (1880) IAD 20 (1991) 39 (2008) 20 (1990) 38 (2008) && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR ANZ530>534- 538>541-543. SMALL CRAFT ADVISORY FROM 4 PM TUESDAY TO MIDNIGHT EST TUESDAY NIGHT FOR ANZ530>534-538>541-543. GALE WARNING FROM 7 AM TO 4 PM EST TUESDAY FOR ANZ530>534- 538>541-543. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TUESDAY NIGHT FOR ANZ535>537-542. && $$ SYNOPSIS...HAS NEAR TERM...SEARS/ADS SHORT TERM...HAS LONG TERM...KLW AVIATION...SEARS/ADS/HAS/KLW MARINE...SEARS/ADS/HAS/KLW CLIMATE...DFH

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.