Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | 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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 080840 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 340 AM EST MON FEB 8 2016 .SYNOPSIS...
-- Changed Discussion --
LOW PRESSURE WILL PASS WELL TO OUR SOUTH AND EAST THIS MORNING. ANOTHER LOW PRESSURE SYSTEM WILL DIVE SOUTH INTO THE OHIO VALLEY TODAY BEFORE PASSING THROUGH OUR AREA TONIGHT INTO TUESDAY. HIGH PRESSURE WILL SLOWLY BUILD TOWARD OUR AREA DURING THE MIDDLE PORTION OF THE WEEK.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
REGION REMAINS SANDWICHED WITH DEEPENING LOW PRESSURE OFFSHORE AND A SECOND LOW OVER THE GREAT LAKES...DIPPING INTO THE OH RIVER VALLEY BY THIS AFTN. ANY PCPN WITH THE LOW OFFSHORE IS REMAINING WELL EAST...AND AS SUCH EXPECTING GENERALLY DRY WX THRU THE FIRST HALF OF TODAY. A WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR THE WESTERN TIER OF COUNTIES FOR TODAY. THE ADVISORY HAS THE POTENTIAL TO BE EXTENDED...OR MAY NEED TO BE UPGRADED TO A WARNING...BUT WILL LET DAY CREW DETERMINE WHERE THE SNOW TOTALS FALL. CONCERNING THE PCPN...SFC LOW TO THE WEST BEGINS TO TRACK CLOSER TO THE MID- ATLANTIC...WHILE UPPER LVL TROUGH DEEPENS ACROSS THE EASTERN US. THIS PLACEMENT OF THE TROUGH IS GOING TO SERVE AS THE AVENUE FOR MULTIPLE IMPULSES TO MOVE THRU THE REGION IN THE COMING DAYS...RESULTING IN INCRG PCPN CHCS. THE FIRST OF THESE REACHES THE WESTERN AREAS BY MIDDAY...PUSHING EAST THRU THE AFTN. AS SUCH...EXPECTING THE PCPN TO MOVE IN MIDDAY OUT WEST...BRIEFLY RAIN/SNOW OR EVEN ALL RAIN. AS THE INTENSITY INCREASES...EXPECTING A COMPLETE CHANGEOVER TO SNOW CORRESPONDING WHERE THE ADVISORY IS. AS THE PCPN PUSHES EAST...GENERALLY EXPECTING ALL RAIN OR MAYBE A RAIN/SNOW MIX WITH HIGHS IN THE 40S...AND LACK OF ANY HEAVIER PCPN HOLDING OFF TILL TONIGHT.
-- End Changed Discussion --
&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --
TRICKY FORECAST STILL IN PLACE FOR THE PCPN TONIGHT THRU TUESDAY NIGHT WITH MANY FACTORS STILL IN PLACE. ONE THING THAT SEEMS TO HAVE BEEN CONSISTENT FOR MANY MODEL RUNS NOW IS THE HINT OF THE HEAVIEST BAND OF PCPN ALIGNING OVER NE MD/SE PA/N DE. AS SUCH...AM ISSUING A WINTER STORM WATCH BEGINNING TONIGHT AND LASTING THRU TUES NIGHT WITH THE POTENTIAL OF 7 INCHES OR MORE OF SNOW IN A 24 HOUR TIME PERIOD FOR FREDERICK COUNTY EAST AND SOUTH TO ACCOUNT FOR BALTIMORE METRO. IN ADDITION TO THE PREVIOUSLY MENTIONED SFC LOW TO THE NORTHWEST...SECONDARY LOW FORMS OVER VA TONIGHT...DEEPENING AS IT PUSHES OFFSHORE DURING THE DAY TUES. 00Z GFS DEEPENS THE LOW MORE THAN THE OTHER MODEL SOLUTIONS...AND AS SUCH...SEEING THE HIGHEST QPF AMTS IN THIS LATEST RUN. WHILE THE PLACEMENT OF THE HEAVIEST BAND IS COMING INTO BETTER AGREEMENT...THE EXACT AMT OF QPF AND THE RESULTING SNOW IS STILL UNCERTAIN...THOUGH WITH INCRSG CONFIDENCE NOW OF SEEING AT LEAST 7 INCHES. TIMING LOOKS TO HAVE THE HEAVIER SNOW MOVE IN SECOND HALF OF TONIGHT...LASTING INTO THE MORNING...WITH ANOTHER BURST PSBL TUES AFTN. THE OTHER ISSUE AT HAND IS THE THERMAL PROFILES AND THE RESULTING P-TYPE. INITIAL AGREEMENT WITH MOST AREAS EAST OF THE BLUE RIDGE SEEING A RAIN/SNOW MIX FIRST PART OF TONIGHT. AS THE PCPN INCREASES IN INTENSITY...GENERALLY AFTR 03/04Z...SHOULD SEE A CHANGEOVER TO SNOW FOR AREAS MAINLY NORTH AND WEST OF A DC TO CHARLOTTESVILLE LINE. PORTIONS OF SOUTHERN MD WILL STAY ALL RAIN...AT LEAST FOR TONIGHT. 00Z MODEL SUITE SHOWING COOLER WET BULB TEMPS...WITH NORTHERN HALF OF THE CWA FULLY BELOW FREEZING...AND DC METRO WITH PERIODS OF AT OR JUST BELOW FREEZING. ANOTHER THING WORKING AGAINST SNOW TOTALS IS THAT AT FIRST NO SNOW MIGHT ACCUMULATE WITH THE WARMER TEMPS. SO A DELAY IN SNOW ACCUMULATION IS PSBL...WHICH MAY AFFECT TOTALS. PCPN BEGINS TO TAPER OFF ACROSS CENTRAL VA TOMORROW NIGHT... LINGERING ALONG THE I-95 CORRIDOR AND THE UPSLOPE REGIONS POTENTIALLY ALL THE WAY THRU WED WITH THE REGION REMAINING ON THE WESTERN SIDE OF THE LOW AND CONTINUOUSLY BEING IMPACTED BY SHORTWAVES PROGRESSING ACROSS THE MID-ATLANTIC. WHILE CRITERIA LVL SNOW WONT BE PSBL OVER THE EASTERN AREAS...ADVISORY LVL SNOW MIGHT BE PSBL ON THE ALLEGHENY FRONT. NOT TO BE FORGOTTEN...THE POTENTIAL FOR COLD TEMPS CONTINUES FOR WED NIGHT...WITH WIND CHILLS BELOW ZERO BCMG MORE LIKELY FOR THE WESTERN PORTIONS OF THE CWA. WILL CONTINUE TO HIGHLIGHT IN THE HWO WITH THE POTENTIAL NEED OF A WIND CHILL ADVISORY.
-- End Changed Discussion --
&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
-- Changed Discussion --
THE H5 TROF AXIS WL REMAIN THRU THE WKND...MEANING THE COLD PTTN WL REMAIN IN PLACE. IF ANYTHING...WE/LL BE GETTING INCRSGLY COLDER. INIT ROUND OF CAA ENDS THU. GUSTY NW WINDS WL RELAX AT THAT POINT. THEN ANOTHER NRN STREAM S/WV AND SFC REFLECTION TRACKS S OF AREA LT FRI...WHICH DRAGS DOWN EVEN COLDER AIR FOR SAT-SUN. FOR THE MOST PART...TEMPS WL REMAIN SUBFREEZING THRUT THE XTNDD. MIN-T WL BE IN THE TEENS...OR LOWER. SAT NGT WUD BE THE COLDEST NIGHT...WITH PSBL SURZERO READINGS IN THE MTNS. WIND CHILLS WL BE A CONCERN. THE LOW ITSELF CUD PROVIDE SCT SHSN JUST ABT ANYWHERE FRI/FRI NGT. IN ADDITION THERE WL BE CONTD UPSLOPE POTL THU BEFORE FLOW BECOMES DISRUPTED. THE PTTN WUD SUPPORT ADDTL UPSLOPE IN THE WAKE OF THE LOW.
-- End Changed Discussion --
&& .AVIATION /09Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
VFR CONDITIONS INITIALLY TODAY. MVFR CIGS AT ALL TERMINALS BY THIS AFTN. AS THE PCPN MOVES IN LATE TODAY/THIS EVENING... EXPECTING CONDITIONS TO DROP QUICKLY TO IFR OR LOWER...ESP TONIGHT WITH THE HEAVIER PCPN. OTHER THAN KCHO...SITES SHOULD START AS LIGHT RAIN...TRANSITIONING TO RAIN/SNOW MIX...EVENTUALLY BCMG ALL SNOW BY TUES MORNING. KCHO LOOKS TO REMAIN ALL RAIN...THOUGH CANNOT RULE OUT A BRIEF RAIN/SNOW MIX TONIGHT. WINDS GENERALLY LESS THAN 12 KTS THRU THE TAF PERIOD. SUB-VFR CONDITIONS WILL CONTINUE TUES WITH THE PCPN...EVENTUALLY IMPROVING TO VFR BY WED MORNING. GUSTY NW WINDS WL BE THE PRIMARY AVN CONCERN THU...W/ SOME G25KT LKLY. ANOTHER DISTURBANCE MAY BRING MORE SHSN FRI. WAY TOO SOON TO TELL IF THIS WL MATERIALIZE...BUT IT CUD BRING MVFR/IFR RESTRICTIONS IF IT DID.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SCA REMAINS IN EFFECT THRU THIS MORNING FOR PORTIONS OF CHESAPEAKE BAY. EXPECTING GENERALLY SUB-SCA CONDITIONS TODAY THRU A GOOD PORTION OF TUES. AS THE LOW PUSHES OFFSHORE AND DEEPENS BY TUES NIGHT...EXPECT SCA CONDITIONS ON AT LEAST THE CHESAPEAKE BAY... SPREADING TO ALL WATERS ON WED. SCA CONDS CONT INTO THU...THEN RELAX AS BRIEF HIPRES CRESTS OVER THE RGN AHD OF ANOTHER DISTURBANCE FRI.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
WATER LVLS ARE ACTUALLY FAIRLY CLOSE TO NORMAL ACROSS THE NRN CHSPK BAY...BUT DEPARTURES ARE STARTING TO BE REALIZED ACROSS THE MID BAY. PLUS...WERE STILL CARRYING CLOSE TO A FOOT ABV ASTRO NORMAS ACROSS THE UPR TIDAL POTOMAC. AS SEVERAL ROUNDS OF LOW PRESSURE PASS OVER/EAST OF THE MOUTH OF THE BAY...ADDITIONAL WATER WILL BE DRAWN IN TO THE ESTUARY. THAT MAY LEAD TO COMPLICATIONS AS EARLY AS THE PM TIDE CYCLE TODAY...CARRYING THROUGH TUESDAY. MINOR INUNDATION WOULD BE MORE LIKELY FOR BOTH CYCLES ON TUESDAY.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...WINTER WEATHER ADVISORY FROM NOON TODAY TO 1 AM EST TUESDAY FOR MDZ501-502. WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE TUESDAY NIGHT FOR MDZ004>006-011-014-503-505>508. VA...WINTER WEATHER ADVISORY FROM NOON TODAY TO 1 AM EST TUESDAY FOR VAZ503-504. WV...WINTER WEATHER ADVISORY FROM NOON TODAY TO 1 AM EST TUESDAY FOR WVZ501>506. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR ANZ532>534-537-540-541-543.
-- End Changed Discussion --
&& $$ SYNOPSIS...HTS NEAR TERM...SEARS SHORT TERM...SEARS LONG TERM...HTS AVIATION...SEARS/HTS MARINE...SEARS/HTS TIDES/COASTAL FLOODING...HTS

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