Area Forecast Discussion
Issued by NWS Sterling, VA

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917
FXUS61 KLWX 081135
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
635 AM EST MON FEB 8 2016

.SYNOPSIS...
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.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
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 LIGHTER SNOW FOR A PERIOD OR EVEN A BREAK IN THE
PCPN...THEN 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.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
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 THRU THE XTNDD. MIN-T WL BE IN
THE TEENS...OR LOWER. SAT NGT WUD BE THE COLDEST NIGHT...WITH PSBL
SUBZERO 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.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
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.

&&

.MARINE...
EXPECTING GENERALLY SUB-SCA CONDITIONS TODAY THRU A GOOD PORTION
OF TUES. OCNL GUSTS TO 20 KTS PSBL THIS EVENING...BUT NOT
WIDESPREAD ENOUGH ATTM TO ISSUE A SCA. 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.

&&

.TIDES/COASTAL FLOODING...
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.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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...NONE.

&&

$$
SYNOPSIS...HTS
NEAR TERM...SEARS
SHORT TERM...SEARS
LONG TERM...HTS
AVIATION...SEARS/HTS
MARINE...SEARS/HTS
TIDES/COASTAL FLOODING...HTS



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