Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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. --
000 FXUS61 KLWX 241704 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1204 PM EST SAT JAN 24 2015 .SYNOPSIS... LOW PRESSURE PUSHES TO THE NORTHEAST TODAY. THE NEXT LOW PRESSURE SYSTEM WILL CROSS THE AREA FROM THE WEST SUNDAY NIGHT THROUGH MONDAY. HIGH PRESSURE IS THEN EXPECTED THROUGH THE MIDWEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HAVE ALLOWED THE REMAINING WINTER WX ADVISORY/WINTER STORM WARNING TO EXPIRE AS OF 17Z. WHILE THERE IS VERY LIGHT PCPN ON-GOING...NOT EXPECTING ENOUGH SNOW ACCUMULATION NOR ANY ICE ACCUMULATION WITH BOTH AIR AND ROADS TEMPS ABV FREEZING TO SEE A NEED TO EXTEND THE PRODUCTS. FOR THE AFTN...SHORTWAVE SWINGING THROUGH THE MID ATLANTIC...WITH ASSOCIATED VORT MAX TRIGGERING ISO-SCT RAIN AND SNOW SHOWERS. PCPN WILL CONTINUE THROUGH THE AFTN...TAPERING OFF FROM WEST TO EAST EVERYWHERE EXCEPT ALLEGHENY FRONT. QPF TOTALS ARE VERY LIGHT...WITH NO SNOW ACCUM EASTERN AREAS...AND ONLY A COUPLE TENTHS OF AN INCH TO THE FAR WEST. THE SKIES WILL ATTEMPT TO SCT THIS AFTN AS WELL WITH DRIER AIR PUSHING IN FROM THE SOUTH...WHICH WILL AID IN INCREASING TEMPS. HIGH TEMPS GENERALLY UPPER 30S TO LOWER 40S. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... SFC LOW PUSHES OFF TO THE NORTHEAST AND THE MAIN FORCING WITH THE UPPER LVL SHORTWAVE SHIFTS EAST. WILL MAINTAIN UPSLOPE SNOW SHOWERS OVER THE ALLEGHENY FRONT REGION WITH A WNW FLOW ON THE BACKSIDE OF THE LOW. THE SHOWERS ARE EXPECTED TO TAPER OFF AS THE WINDS BACK TO THE SW NEAR DAYBREAK SUN MORNING...BUT THE LACK OF PCPN WILL BE SHORT LIVED AS AN ALBERTA CLIPPER QUICKLY APPROACHES THE REGION. TEMPS SAT NIGHT NEAR NORMAL...WITH EVERYWHERE IN THE UPPER 20S TO RIGHT AROUND 30. && .LONG TERM /SUNDAY THROUGH FRIDAY/... INCREASED POPS AND MODIFIED FORECAST SNOWFALL AMTNS FOR LATE SUN INTO MON. THE BULK OF THE ACTIVITY STILL EXPECTED DURING THE OVERNIGHT HRS INTO THE EARLY MRNG HRS/FIRST HALF OF MON. HOWEVER...THIS LOOKS TO BE A TRANSITIONAL SYSTEM LIKE THE FEATURE FROM A FEW DAYS AGO - ONLY MORE INTENSE FROM START TO FINISH. MOST CLIPPER SYSTEMS MOVE QUICKLY AND THIS WILL BE NO EXCEPTION...BUT INSTEAD OF A DIRECT PATH TO THE MID-ATLC - THE UPPER FEATURE WILL BE FORCED SWD FOR A BRIEF DECELERATION PERIOD OVER THE UPPER MIDWEST. WHILE SPREADING SNOW SHOWERS ACROSS THE OHIO VLY AND WAITING FOR THE OTHER POTENT NRN ATLC SYSTEM TO MOVE FURTHER OFF THE COAST...THE FEATURE WILL MAKE A DIVE TOWARD THE SRN APLCNS. ALL GUIDANCE IS IN GOOD AGREEMENT ON THIS...W/ ONLY SLIGHTLY VARYING DIFFERENCES IN THE OVERALL INTENSITY AND EXACT TRACK. THE EURO HOWEVER MAKING A BIGGER EFFORT FOR THE TRANSITIONAL PHASE DIRECTLY OVER OUR AREA LATE SUN INTO EARLY MON. THE LATEST RUN AND EVEN MORE RECENT ONES HAVE EFFECTIVELY DISSIPATED THE WRN PRECIP TO RECONVENE IT OVER THE ERN HALF OF THE AREA/CHESPKE BAY. THE GFS ON THE OTHER HAND WRINGS OUT MOST OF IT`S PRECIP - IN THIS CASE SNOW - OVER THE WRN HALF OF THE AREA THEN DISPLACES THE FORCING OFF THE COAST W/ ONLY LIGHT/INTERMITTENT SNOWS OVER THE ERN HALF OF THE AREA DURING THE DAY ON MON. MAY NEED TO CONSIDER WINTER STORM WATCHES FOR PORTIONS OF THE AREA...ESPEC THE WRN SECTIONS OF THE CWA - CERTAINLY THE APLCNS AND POSSIBLY INTO THE SHEN VLY/BLUE RIDGE IF GUIDANCE COMES IN BETTER AGREEMENT W/ QPF/TIMING/PLACEMENTS. DIRECTLY BEHIND THE EXITING AND STRENGTHENING COASTAL SYSTEM WILL BE A SECONDARY UPPER WAVE THAT GETS PULLED DOWN ACROSS THE GREAT LAKES TOWARD THE MID-ATLC ON TUE. THE FEATURE ITSELF WILL BE DISSIPATING LATE MON NIGHT UPON APPROACH TO THE UPPER MIDWEST...CARRYING A GOOD SHOT OF COLD AIR AND ENOUGH LOW LEVEL MOISTURE TO CREATE SCATTERED SNOW SHOWERS. AS THE WAVE PULLS AROUND THE BASE OF THE UPPER TROUGH...THE SNOW SHOWERS WILL SWING ACROSS THE MID-ATLC DURING THE DAYTIME HRS TUE BUT LIKELY DISSIPATING TOWARD THE LATTER HALF OF THE DAY. AS THIS UPPER WAVE TRANSITIONS OFF THE COAST...THE MOISTURE WILL BE CUT OFF QUICKLY AND PRECIP WILL END - UNTIL YET ANOTHER UPPER WAVE APPROACHES FROM THE NORTH ON WED. THIS FEATURE WILL BE LESS LIKELY TO AFFECT THE AREA OUTSIDE OF SOME UPSLOPE MTNS SNOWS BUT WILL REINFORCE THE COLDER AIRMASS DURING THE MIDDLE OF THE WEEK. THE NEXT WX CONCERN FOR THE EXTENDED IS THE COLD. THE TWO EXTRA WAVES OF REINFORCING COLD AIR FROM THE NORTH TUE AND AGAIN ON WED WILL NOT ONLY KEEP OUR DAILY HIGHS MAXED-OUT NEAR THE FREEZING MARK BUT ALLOW OVERNIGHT LOWS TO DROP WELL INTO THE TEENS AND 20S ACROSS THE REGION...SOME SINGLE DIGITS OVER THE APLCNS. HIGH PRES BRIEFLY BUILDS IN FROM LATE WED INTO THU AND A RELATIVE WARM-UP BUT ONLY INTO THE U30S ON THU AFTN. ANOTHER CLIPPER WILL BE WELL ON ITS WAY TOWARD THE AREA DURING LATTER HALF OF THE WEEK...MOVING ACROSS THE REGION LIKELY LATE THU INTO FRI ACCORDING TO THE RECENT GFS AND EURO RUNS. NOT A COMPLETELY SIMILAR SOLN BETWEEN THEM BUT ELEMENTS OF THE SAME LOOK...EXCEPT THE GFS HOLDS A MORE COMPACT UPPER WAVE THAT SLIDES OVER THE AREA AND BRINGS MORE PRECIP TO OUR REGION. && .AVIATION /17Z SATURDAY THROUGH WEDNESDAY/... OVC MVFR CIGS WITH PERIODS OF IFR CONDITIONS THRU 18Z. LIGHT PCPN PSBL LATE THIS MORNING/EARLY AFTN BUT WILL BE MORE PERIODIC IN NATURE AND MAINLY RAIN. -SN PSBL AT KMRB. CIGS/VIS WILL IMPROVE THIS AFTN WITH NWLY FLOW GUSTING 20 TO 25 KT. VFR CONDITIONS TNGT. A CLIPPER SYSTEM WILL QUICKLY ARRIVE DURING THE DAYTIME HRS ON SUN...MAINLY THE LATTER HALF W/ MAINLY SNOW UPON ARRIVAL. PERIODS OF SNOW FOR THE REGION LATE SUN INTO MON. IFR CONDS OR LOWER W/ THE HEAVIEST ACTIVITY...THEN GUSTY NLY WINDS EARLY MON AS A LOW DEVELOPS AND STRENGTHENS OFF THE COAST. LINGERING SNOW SHOWERS ON TUE AND SOME SUB-VFR CONDS FOR THE FIRST HALF OF THE DAY. ACTIVITY MOVING OFF THE COAST BY MID-WEEK. ANOTHER COLD/POTENTIALLY SNOWY CLIPPER SYSTEM ON FRI. && .MARINE... SCA IN EFFECT FOR SRN PORTIONS OF THE WATERS...AND THEN ALL WATERS TODAY WITH 20 TO 25 KT GUSTS EXPECTED. LINGERING SCA GUSTS UP TO 20 KT THIS EVENING...THEN DECREASING OVERNIGHT. WINDS REMAIN MAINLY BELOW SCA CRITERIA SUNDAY...WITH LOW CHC OF OCNL GUSTS TO 18 KT PSBL SUN AFTN. HIGHER CONFIDENCE OF GUSTS INTO THE 20S ON MONDAY WITH NORTHERLY FLOW SO SCA WILL MOST LIKELY BE NEEDED AFTER 12Z MON. SMALL CRAFT ADVISORY MAY BE NEEDED MONDAY EVENING AS NORTHERLY WINDS GUST OVER 20 KNOTS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ530>543. && $$

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