Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | 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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
488 FXUS61 KLWX 112021 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 321 PM EST THU FEB 11 2016 .SYNOPSIS... HIGH PRESSURE BUILDS IN ACROSS THE REGION THROUGH FRIDAY. A STRONG COLD FRONT WILL CROSS THE REGION FRIDAY NIGHT WITH ARCTIC HIGH PRESSURE BUILDING IN THE WAKE FOR THE WEEKEND. LOW PRESSURE MAY IMPACT THE AREA MONDAY AND TUESDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
SFC HIGH PRESSURE POISED OVER THE UPPER MS VALLEY THIS AFTERNOON. MID-ATLANTIC STILL REMAINS UNDER CYCLONIC FLOW WITH LONG-WAVE TROUGH OVER EASTERN N AMERICA. HOWEVER HEIGHTS GRADUALLY RISING AND BL MOISTURE THINNING AS EVIDENT IN RECENT VIS SATELLITE. THREAT FOR FLURRIES AND ISOLD SNOW SHOWERS ACROSS NORTHERN MD WILL CONTINUE TO WANE. THE GUSTY WINDS WILL ALSO DIMINISH DURING THE LATE AFTERNOON AS THE HIGH BUILDS. THE HIGH SLIPS TO THE SOUTH TONIGHT. ANY UPSLOPE SNOW SHOWERS WILL QUICKLY COME TO AN END THIS EVENING. OTHERWISE JUST A COLD NIGHT WITH LOWS IN THE TEENS IN MOST LOCATIONS. WIND CHILLS WILL BE LESS OF A CONCERN WITH THE LIGHTER WINDS.
-- End Changed Discussion --
&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
SFC HIGH PRESSURE QUICKLY SLIDES OFFSHORE EARLY FRIDAY WITH RETURN FLOW BRINGING SLIGHTLY HIGHER TEMPERATURES (BUT STILL ON EITHER SIDE OF FREEZING)...AS WELL AS INCREASING CLOUDS/MOISTURE. ONE LOW PRESSURE CENTER ASSOCIATED WITH AN ARCTIC FRONT WILL BE MOVING THROUGH THE GREAT LAKES...WHILE ANOTHER TAKES SHAPE NEAR THE CAROLINA COAST IN RESPONSE TO A SOUTHERN VORT MAX. MAJORITY OF GUIDANCE KEEPS THE COASTAL LOW EFFECTS TO OUR SOUTHEAST...BUT DID INTRODUCE LOW END POPS ACROSS SOUTHERN MD. THE MORE IMPORTANT WEATHER FEATURE FOR OUR AREA WILL BE A PAIR OF BOUNDARIES TRAILING THE NORTHERN LOW CENTER. INCREASING SIGNAL IN MODEL GUIDANCE OF A BAND OF SNOW SHOWERS DEVELOPING AHEAD OF THE FIRST BOUNDARY AND HAVE THUS INCREASED POPS ACROSS THE AREA WITH SUFFICIENT MOISTURE AVAILABLE. STILL SOME DIFFERENCES ON TIMING AND COVERAGE...BUT THERE IS POTENTIAL FOR THESE SNOW SHOWERS TO REACH THE METRO AREA DURING PORTIONS OF EVENING RUSH HOUR. WITH THE ANTECEDENT COLD CONDITIONS...ANY SNOW WOULD STICK ON UNTREATED ROADS. CERTAINLY A SITUATION TO PAY ATTENTION TO. THIS WILL ALSO MARK THE BEGINNING OF A PERIOD OF UPSLOPE SNOW...HEAVIEST FRIDAY AFTERNOON AND NIGHT...BUT LASTING THROUGH SATURDAY. WINTER WX ADVISORY POSSIBLE AS SEVERAL INCHES OF SNOW EXPECTED. SECOND BOUNDARY WILL MOVE THROUGH LATE FRIDAY NIGHT AND MARK THE LEADING EDGE OF THE COLDEST AIRMASS. EVEN THOUGH CHANCES DECREASE A BIT...SOME SNOW SHOWERS COULD STILL MAKE IT ACROSS ESPECIALLY NORTHERN PARTS OF THE AREA. TEMPERATURES WILL FALL INTO THE TEENS IN MOST AREA AND WINDS INCREASE SUBSTANTIALLY WITH GUSTS OF 20-30 MPH BEHIND THE FRONT. THIS MAY NECESSITATE WIND CHILL ADVISORIES IN THE HIGHER ELEVATIONS. SATURDAY-SATURDAY NIGHT WILL BE THE COLDEST OF THE STRETCH WITH 850 MB TEMPS BELOW -20C AND STIFF WINDS. HIGHS ON SATURDAY WILL ONLY BE IN THE TEENS AND 20S WITH LOWS SATURDAY NIGHT IN THE SINGLE DIGITS...AND BELOW ZERO IN THE POTOMAC HIGHLANDS. WIND GUSTS OF AT LEAST 30-40 MPH WILL OCCUR SATURDAY...AND THERE IS A CHANCE OF WIND ADVISORY CRITERIA. THE WINDS WILL ONLY DIMINISH SLIGHTLY SATURDAY NIGHT. WIND CHILLS MAY FAIL TO RISE ABOVE +10F ON SATURDAY IN MUCH OF THE AREA...AND FALL BELOW ZERO SATURDAY NIGHT. WIND CHILL ADVISORY CRITERIA (-5F) WILL LIKELY BE MET OVER MOST OF THE AREA...AND WIND CHILL WARNINGS (-25F) ARE POSSIBLE ALONG THE ALLEGHENIES. OTHER ISSUE FOR SATURDAY WILL BE A CONTINUED CHANCE OF SNOW SHOWERS AND STREAMERS ACROSS THE NORTHERN PART OF THE AREA. SNSQ PARAMETER IN THE NAM AND GFS...AND EVEN 12Z GFS QPF OUTPUT...PLACE THE FAVORED AREA ACROSS NORTH CENTRAL MD INCLUDING BALTIMORE.
-- End Changed Discussion --
&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
LATEST MODEL GUIDANCE IS SUGGESTING A PRETTY QUICK EROSION OF AN IMPRESSIVELY COLD AIRMASS BEGINNING LATE SUNDAY AND INTO EARLY NEXT WEEK. NORMALLY THIS TYPE OF QUICK EROSION WOULD FORCE SOME KIND OF PRECIPITATION...AND AS SUCH A LOT OF THE GUIDANCE IS TRYING TO BRING SOME PRECIPITATION OVER THE AREA SUNDAY NIGHT INTO MONDAY. A STRONG UPPER-LEVEL DISTURBANCE WILL FORCE A SURFACE LOW OVER THE SOUTHEASTERN CONUS...WHICH WILL THEN MOVE NORTHEAST NEAR OR OVER THE AREA. GUIDANCE DIVERGES GREATLY ON SURFACE LOW TRACK AND HOW MUCH COLD AIR IS LEFT IN PLACE. BEST CHANCE FOR PROLONGED WINTRY PRECIPITATION WOULD BE WEST OF THE BLUE RIDGE MOUNTAINS. EAST OF THERE PRECIPITATION MAY VERY WELL CHANGE TO RAIN BY TUESDAY. THERE WILL LIKELY BE SOME WINTRY PRECIPITATION EARLY NEXT WEEK...BUT AMOUNTS ARE HIGHLY UNCERTAIN AT THIS TIME. AN ACTIVE PATTERN MAY PERSIST INTO THE MIDDLE PART OF NEXT WEEK BUT DETAILS ARE FUZZY GIVEN THE UNCERTAIN EVOLUTION OF THE EARLY WEEK SYSTEM.
-- End Changed Discussion --
&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
PRIMARY ISSUE AFFECTING THE TERMINAL THROUGH THE WEEKEND WILL BE WIND. WNW GUSTS UP TO 30 KT WILL QUICKLY DIMINISH THIS EVENING AND ANY LINGERING CIGS AT 050-060 WILL DISSIPATE. VFR THROUGH THE BULK OF FRIDAY WITH LIGHT SW WINDS. WILL HAVE TO WATCH FOR SNOW SHOWERS AHEAD OF AN ARCTIC COLD FRONT LATE FRIDAY AFTERNOON INTO EVENING. NOT HIGH ENOUGH CONFIDENCE TO PUT IN THE EXTENDED TAFS NOW...BUT THESE COULD CAUSE BRIEF IMPACTS. WINDS INCREASE SHARPLY BEHIND FRONT...WITH NW GUSTS 25-35 KT CONTINUING THROUGH SATURDAY AND ONLY GRADUALLY DIMINISHING SATURDAY NIGHT. THERE WILL BE A LINGERING THREAT OF ISOLD/SCT SNOW SHOWERS THROUGH SATURDAY...ESPECIALLY BWI/MTN. SUB-VFR PSBL SUN NGT INTO MON IF PRECIP DEVELOPS. WINDS LIGHT SUN NGT BCMNG GNLY ELY MON.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
W/NW WINDS CONTINUING TO GUST TO 30 KT THROUGH THIS AFTERNOON BUT QUICKLY DROPPING OFF THIS EVENING. THE SCA OVER THE BAY MAY BE ABLE TO BE CANCELED EARLY AS WINDS ARE FORECAST TO LIGHTEN AFTER MIDNIGHT. LIGHT SW FLOW TO START FRIDAY BUT THAT WILL QUICKLY CHANGE DURING THE EVENING AS ARCTIC FRONT MOVES THROUGH WITH CHANCE FOR SNOW SHOWERS. W/NW WINDS WILL INCREASE IMMEDIATELY AND WILL BE ISSUING SCA. THIS MAY NEED TO BE UPGRADED TO A GALE WARNING...BUT CONFIDENCE NOT HIGH IN THAT OCCURRING UNTIL AFTER 12Z SATURDAY. GALES THEN APPEAR LIKELY SATURDAY AND A PORTION OF SATURDAY NIGHT. THE STRONG WINDS AND COLD TEMPERATURES OVER THE RELATIVELY WARM WATERS WILL LIKELY RESULT IN A FREEZING SPRAY THREAT. WINDS DROP BELOW GALE RELATIVELY QUICKLY SUNDAY...AND REMAIN RELATIVELY LIGHT INTO MONDAY.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ530>534- 537>543. SMALL CRAFT ADVISORY FROM 6 PM FRIDAY TO 6 AM EST SATURDAY FOR ANZ530>543. SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR ANZ535- 536.
-- End Changed Discussion --
&& $$ SYNOPSIS...ADS NEAR TERM...ADS SHORT TERM...ADS LONG TERM...DFH AVIATION...ADS/DFH MARINE...ADS/DFH

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