Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 030704
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
204 AM EST TUE MAR 3 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD ACROSS THE AREA TONIGHT. A WARM FRONT
WILL PUSH THROUGH THE AREA TUESDAY NIGHT. A COLD FRONT WILL MOVE
INTO THE REGION WEDNESDAY FOLLOWED BY HIGH PRESSURE FOR THURSDAY
LASTING INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TODAY/...
JUST A QUICK HEADLINE UPDATE THAT THE START TIME OF THE WINTER
WEATHER ADVISORY WAS DELAYED UNTIL 10 AM FOR THE SHENANDOAH
VALLEY...WRN MD...AND N-CNTRL VA AND UNTIL NOON FOR THE GREATER
BALTIMORE-WASHINGTON METRO AND SRN MD. END TIMES REMAIN THE
SAME. GUIDANCE CONSENSUS IS PRECIP COMING IN RATHER LATER THAN THE
PREVIOUS HEADLINE SEQUENCE WOULD SUGGEST. THE MORNING COMMUTE
LOOKS UNAFFECTED EAST OF THE BLUE RIDGE. THE THREAT IS FOCUSED ON
THE AFTERNOON/EVENING RUSH.

PREVIOUS...

HIGH PRESSURE WILL BUILD INTO THE MID ATLANTIC REGION ONIGHT.
WINDS WILL DIMINISH BY SUNSET AND WITH MOSTLY CLEAR
SKIES...TEMPERATURES WILL FALL OFF QUICKLY...DROPPING TO THE
LOWER 20S IN MOST LOCATIONS EXCEPT TEENS OVER THE NORMALLY COLDER
AREAS WEST OF THE BLUE RIDGE.

CLOUDS WILL BE ON THE INCREASE FROM WEST TO EAST BY EARLY TUESDAY
MORNING AS THE NEXT WEATHER SYSTEM APPROACHES. LIGHT PRECIPITATION
IS EXPECTED TO BEGIN OVER THE WESTERN SLOPES OF THE ALLEGHENY
FRONT THEN SPREADING EAST ACROSS THE REMAINDER OF THE FORECAST
AREA MID TO LATE MORNING.

PROFILES INDICATE THERE IS ENOUGH COLD AIR FOR PRECIPITATION TO
START AS A MIXTURE OF SNOW AND SLEET BUT A FAIRLY QUICK TRANSITION
TO SLEET AND FREEZING RAIN IS EXPECTED BY MIDDAY TO EARLY AFTERNOON.
SNOWFALL AMOUNTS WILL BE LIGHT. LIGHT FREEZING RAIN/FREEZING
DRIZZLE WILL BECOME THE MAIN P-TYPE BY AFTERNOON WITH A FEW
HUNDREDTHS TO ONE TENTH OF AN INCH OF ICE ACCRETION EXPECTED.
SURFACE TEMPERATURES WILL BE COLD ENOUGH FOR SOME SLIPPERY TRAVEL
TO DEVELOP FOR THE AFTERNOON AND EVENING COMMUTE. A WINTER WEATHER
ADVISORY IS IN EFFECT TO COVER THIS THREAT.

WARMER AIR WILL GRADUALLY FILTER IN FROM SOUTH TO NORTH AS SOUTHERLY
WINDS INCREASE DURING THE LATE AFTERNOON AND EARLY EVENING. RAIN
WILL BECOME MORE LIKELY OVER CENTRAL AND SOUTHERN LOCATIONS. LIGHT
FREEZING RAIN WILL LIKELY HOLD ON LONGER FOR THE FAR NORTH AND WEST
SUBURBS OF BALTIMORE AND WASHINGTON DC INTO THE EVENING. HIGH
TEMPERATURES TOMORROW WILL ONLY RISE INTO THE 30S IN MOST LOCATIONS.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
COLD AIR MAY BE LINGERING INTO THE ELY EVNG N OF THE PTMC RIVER
TUE EVNG...OTRW WAA WL MAKE ITS WAY TO THE SFC. SHUD HV WARMING
TEMPS THRUT THE NGT. THEREFORE...WL BE RUNNING W/ A PTYPE OF RA...
W/ JUST A LITTLE LINGERING FZRA TO THE N.

THE MAIN PTYPE ISSUE FOR OVNGT TUE INTO WED WL BE RA. A SOLID
PLUME OF MSTR WL BE CHANNELED EWD FM THE WRN GLFMEX AHD OF AN
APPROACHING CDFNT. AM GOING W/ QPF ARND A HALF INCH...CLOSER TO
AN INCH FOR THE MTNS. MORE ON THIS IN THE HYDRO SECTION BELOW.

CFP WL COME LT IN THE DAY. WE WL BE STARTING FM A BASE IN THE UPR
40S NORTH TO UPR 50S SOUTH /BLENDED NEWER GDNC INTO THE ENSEMBLE
MAXT FCST/ SO EVEN AFTER FROPA...PCPN WL STILL BE RAIN. PROBLEM
IS...SFC TEMPS WL KEEP DROPPING THRU THE AFTN-EVNG WHILE THE PLUME
OF MSTR CONTS TO STREAM EWD ABV IT. THAT WUD SUPPORT PCPN CHGG
OVER TO SNW /OR PERHAPS SLEET/ WED NGT. QSTNS REVOLVE ARND THE
TIMING OF THAT TRANSITION ALONG W/ HOW MUCH MSTR WL BE AVBL AT
THAT TIME. AN UPR JET WL BE SUPPORTIVE OF PCPN GENERATION...AS WE
WL BE IN THE RRQ. AT THIS TIME...IT SEEMS APPARENT THAT THERE WL
BE MEASURABLE SNOW WED NGT INTO THU MRNG. IT CUD BE MORE THAN
JUST A LTL. HV THIS IN THE HWO ATTM. REFER TO OUR PROBABILISTIC
DATA VIA OUR WEBSITE FOR THE RANGE OF POSSIBILITIES.

HV SNOW TAPERING OFF DURING THE DAY ON THU. DOUBT THERE WL BE MUCH
OF A TEMP RISE.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AFTER A FEW BUSY WX DAYS...HIGH PRESSURE SETTLES INTO THE REGION
OVERNIGHT THURSDAY. EXPECT LIGHT WINDS WITH CLEARING SKIES...LEADING
TO STRONG RADIATIONAL COOLING AND VERY COLD TEMPERATURES...
ESPECIALLY IF THERE IS SNOW COVER FROM THE THURSDAY SYSTEM. HIGH
TEMPERATURES WILL REMAIN NEAR FREEZING FRIDAY DESPITE THE RETURN
OF WAA. AFTER ANOTHER COLD NIGHT FRIDAY...TEMPERATURES BEGIN TO
REBOUND SATURDAY AND EVEN MORE SUNDAY. HOWEVER...THEY WILL REMAIN
IN THE MID/UPPER 40S...WHICH IS BELOW AVERAGE FOR THIS TIME OF
YEAR.

AT THIS POINT LEFT WEEKEND PRECIP FREE. BUT...RECENT MODEL RUNS
APPEAR TO HAVE A SYSTEM DEVELOPING IN THE DEEP SOUTH AND PERHAPS
BEGINNING TO IMPACT OUR AREA ON SUNDAY. WOULD LIKE TO SEE MORE RUN
TO RUN CONSISTENCY BEFORE INTRODUCING POPS.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
VFR EXPECTED THROUGH 12Z TUESDAY. LIGHT PRECIPITATION WILL MOVE
IN FROM WEST TO EAST BY MID TO LATE MORNING. HAVE INTRODUCED LIGHT
SNOW/SLEET MIXTURE AT MOST TERMINALS AROUND MIDDAY BUT EXPECT
FREEZING RAIN TO BECOME THE MAIN P-TYPE BY AFTERNOON AND EVENING.
THE PRECIPITATION MAY CHANGE TO ALL RAIN CENTRAL AND SOUTH WITH
LIGHT FREEZING RAIN/FREEZING DRIZZLE HOLDING ON LONGER NEAR KBWI.

MVFR TO IFR FLGT CONDS SHUD BE WIDESPREAD TUE NGT THRU THU. MAINLY
RA TUE NGT AND WED. SNOW SHUD BE THE PRIMARY PTYPE WED NGT INTO
THU. DEPENDING UPON TIMING...LIFR PSBL.

AT THIS POINT NOT EXPECTING ANY AVIATION CONCERNS FROM THURSDAY
NIGHT THROUGH SUNDAY.

&&

.MARINE...
WINDS HV DIMINISHED ON THE WATERS. SMALL CRAFT CONDITIONS COULD
DEVELOP TUESDAY NIGHT. VISIBILITY WILL BE REDUCED IN FROZEN
PRECIPITATION TUESDAY AFTERNOON INTO TUESDAY NIGHT.

THERE IS THE POTENTIAL FOR A BRIEF PERIOD OF SCA THURSDAY
AFTERNOON AND NIGHT BEFORE WINDS SUBSIDE. AFTER THIS NOT
EXPECTING MARINE CONCERNS THROUGH SUNDAY.

&&

.HYDROLOGY...
WE HAVE BEEN ADVERTISING THE POTENTIAL OF MIDWEEK FLOODING IN THE
HAZARDOUS WEATHER OUTLOOK. LIQUID PRECIP FCST FROM WPC PUTS MUCH OF
THE FCST AREA IN A MINIMA FOR AMOUNTS...AROUND AN INCH OR LESS IN
MANY AREAS. WITH TEMPERATURES EXPECTED TO RISE INTO THE 50S ON
WEDNESDAY...THERE WILL BE SOME...POSSIBLY A LOT OF...MELTING OF THE
EXISTING SNOWPACK...WHICH COMPUTER MODELS AND OBSERVATIONS INDICATE
CONTAINS ANYWHERE FROM 3/4 INCH TO 2 INCHES OF SNOW WATER
EQUIVALENT. THIS COMBINATION MAY LEAD TO MINOR FLOODING AS THE RAIN
FALLS ON WEDNESDAY.

ALTHOUGH RIVER ICE IS NOT ESPECIALLY THICK...IT WILL HAVE TO BE
MONITORED FOR POTENTIAL ROLE IN AFFECTING RUNOFF. ALSO...PLOWED SNOW
IS LIKELY COVERING SOME OF THE DRAINS OUT THERE...WHICH COULD CAUSE
MORE POOR DRAINAGE FLOODING THAN WOULD OTHERWISE USUALLY BE
EXPECTED.

WORTH NOTING...CURRENT FORECAST RAIN TOTALS ARE ON THE LOWER SIDE OF
THE ENSEMBLE SUITES OF THE GEFS AND SREF. PLEASE CONTINUE TO MONITOR
THE FORECAST FOR UPDATES AS THE EVENT GETS CLOSER.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER WEATHER ADVISORY FROM NOON TODAY TO 10 PM EST THIS
     EVENING FOR DCZ001.
MD...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST
     THIS EVENING FOR MDZ501-502.
     WINTER WEATHER ADVISORY FROM NOON TODAY TO 10 PM EST THIS
     EVENING FOR MDZ004>006-011-013-014-503>508.
     WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST
     THIS EVENING FOR MDZ003.
     WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 PM EST THIS
     EVENING FOR MDZ016>018.
VA...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST
     THIS EVENING FOR VAZ503-504.
     WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST
     THIS EVENING FOR VAZ025>031-036>040-050-051-501-502-507-
     508.
     WINTER WEATHER ADVISORY FROM NOON TODAY TO 10 PM EST THIS
     EVENING FOR VAZ053-054-505-506.
     WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 PM EST THIS
     EVENING FOR VAZ052-055>057.
WV...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST
     THIS EVENING FOR WVZ050-055-501>506.
     WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST
     THIS EVENING FOR WVZ051>053.
MARINE...NONE.

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
HYDROLOGY...


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