Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 220838
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
338 AM EST SUN FEB 22 2015

.SYNOPSIS...
A COLD FRONT WILL PASS THROUGH THE REGION TODAY. AN UPPER-LEVEL
DISTURBANCE WILL PASS THROUGH THE AREA TONIGHT AND CANADIAN HIGH
PRESSURE WILL BUILD OVERHEAD FOR MONDAY. THE HIGH WILL SHIFT OFF THE
COAST TUESDAY AND A COLD FRONT IS EXPECTED TO PASS THROUGH TUESDAY
NIGHT INTO WEDNESDAY. CANADIAN HIGH PRESSURE WILL RETURN FOR THE
MIDDLE AND LATTER PORTION OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
HAVE KEPT THE WINTER HEADLINES IN EFFECT FOR EARLY THIS MORNING.
AREAS OF LIGHT RAIN AND FREEZING RAIN CONTINUE WITH MOST
OBSERVATIONS NEAR FREEZING. HOWEVER...PAVEMENT TEMPERATURES REMAIN
COLD AND EVEN WITH TEMPERATURES ABOVE FREEZING...HAZARDOUS
TRAVELING CONDITIONS ARE EXPECTED THIS MORNING.

THE DRY SLOT WILL CONTINUE TO OVERSPREAD THE AREA THIS MORNING AND
PRECIPITATION SHOULD TAPER OFF ACROSS MOST AREAS BY 6 AM. THE ONE
EXCEPTION WILL BE ACROSS SOUTHERN MARYLAND...WHERE RAIN MAY HANG ON
THROUGH THE MORNING HOURS BEFORE THE DRIER AIR FINALLY WORKS ITS WAY
IN BEHIND A DEPARTING UPPER-LEVEL DISTURBANCE. A COLD FRONT IS
EXPECTED TO PASS THROUGH THE AREA LATE THIS MORNING AND AFTERNOON.
PLENTY OF DRY AIR WILL PREVENT PRECIPITATION ACROSS MOST AREAS WITH
THE FRONTAL PASSAGE. IN FACT...DRIER AIR BEHIND THE FRONT WILL ALLOW
FOR SOME SUNSHINE AND NOTICEABLY MILDER CONDITIONS COMPARED TO WHAT
HAS OCCURRED RECENTLY. WITH SOME SUNSHINE...AND A NORTHWEST FLOW
THIS AFTERNOON THE FORECAST LEANS TOWARD THE WARMER MAV GUIDANCE
OVER THE MET GUIDANCE OR 2M TEMPS FROM THE NAM/GFS. HOWEVER...DID
NOT GO QUITE AS WARM AS THE MAV GUIDANCE DUE TO THE SNOW COVER. MAX
TEMPS ARE FORECAST TO RANGE FROM THE LOWER UPPER 20S AND LOWER 30S
ALONG THE ALLEGHENY HIGHLANDS...TO THE UPPER 30S NEAR THE
MASON-DIXON LINE...TO THE LOWER AND MIDDLE 40S NEAR WASHINGTON AND
BALTIMORE. THE WARMER TEMPS WILL ALLOW FOR ROAD CONDITIONS TO
IMPROVE LATER THIS MORNING AND AFTERNOON.

THE COLD ADVECTION BEHIND THE COLD FRONT WILL INCREASE TONIGHT AS
CANADIAN HIGH PRESSURE BUILDS TOWARD THE REGION. ALSO...LIGHT WINDS
THIS EVENING WILL ALLOW FOR RADIATIONAL COOLING AND WITH THE
SNOWPACK IN PLACE THIS WILL CAUSE TEMPS TO DROP BELOW FREEZING
ACROSS MOST LOCATIONS SHORTLY AFTER SUNSET. THEREFORE...ANY WET OR
SLUSHY ROADS WILL RE-FREEZE THIS EVENING.

AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE AREA LATE TONIGHT.
A FLURRIES OR FEW SNOW SHOWERS CANNOT BE RULED OUT.
HOWEVER...MOISTURE WILL BE LIMITED SO ANY SNOW SHOWERS WILL BE
ISOLATED WITH LITTLE OR NO SNOW ACCUMULATION IS EXPECTED. MIN
TEMPS ARE FORECAST TO RANGE FROM THE SINGLE DIGITS IN THE
ALLEGHENY HIGHLANDS...TO THE MID AND UPPER 20S IN DOWNTOWN
WASHINGTON AND BALTIMORE.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
CANADIAN SFC HIGH SINKS SOUTH INTO THE CENTRAL PLAINS MONDAY...WITH
THE MID ATLANTIC REMAINING ON THE EASTERN PERIPHERY OF THE HIGH
THROUGH THE DAY. NW FLOW COULD RESULT IN UPSLOPING SNOW
SHOWERS...MAINLY THROUGH MONDAY MORNING. BUT WITH THE DRIER AIRMASS
MOVING IN...ONLY HAVE CHC IN FOR THE AM...AND DRY WX BY THE AFTN.
WEAK LOW PRESSURE RIDING THE FRONT TO THE SOUTH COULD BRING LIGHT
PCPN UP INTO CENTRAL VA IN THE MORNING...AS HINTED ON THE GFS AND
ECMWF...SO HAVE INCLUDED SLIGHT CHC POPS TO ACCOUNT FOR THIS.
OTHERWISE....THE HIGH WILL KEEP THINGS QUIET AND COLD THROUGH MONDAY
NIGHT.

FOR MON NIGHT...POTENTIAL FOR WIND CHILL ADVISORIES...MAINLY WEST OF
THE BLUE RIDGE MONDAY NIGHT AS 850 MB TEMPS DROP TO AROUND 15 BELOW
CELSIUS...AND POSSIBLY NORTHERN SECTIONS OF BALTIMORE METRO. WINDS
WILL BE ON THE LIGHT SIDE...BUT STILL ENOUGH ESP AT HIGHER
ELEVATIONS TO PUSH APPARENT TEMPS DOWN TO BETWEEN 10 AND 20 BELOW.
00Z MODEL RUNS KEEPING THE COLDEST AIR NORTH OF THE MASON-DIXON
LINE...AND WITH THE LIGHT WINDS KEEPING APPARENT TEMPS SIMILAR TO
ACTUAL TEMPS...NOT EXPECTING WIND CHILL ADVISORIES ELSEWHERE AT THIS
TIME. HOWEVER...IT WILL STILL BE VERY COLD WITH LOWS IN THE SINGLE
DIGITS ABV ZERO...AND BELOW ZERO WESTERN AREAS.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
DRY WEATHER FOR AT LEAST DAYTIME TUESDAY AS THE HIGH SLIDES OFFSHORE
AHEAD OF THE NEXT FRONTAL SYSTEM. GENERAL CONSENSUS AMONGST THE 00Z
MODEL SUITE WAS NOW SWINGING THE FRONT THROUGH TUES NIGHT/WED
MORNING. THE SYSTEM IS STILL UNIMPRESSIVE WITH PCPN AS THE DRY
AIRMASS FROM THE HIGH WILL BE HARD TO OVERCOME IN THE SHORT TIME.
UPPER LVL TROUGH NOT DIGGING AS DEEP AS ON PREVIOUS RUNS AS
WELL...KEEPING THE BETTER FORCING ALOFT TO THE NORTH. AS SUCH...HAVE
CHC POPS IN FOR THE POTOMAC HIGHLANDS WITH THE UPSLOPING COMPONENT.
TEMPS COLD ENOUGH SO ANY PCPN WOULD BE IN THE FORM OF SNOW.

ANOTHER CANADIAN HIGH BUILDS IN BEHIND THE COLD FRONT...BRINGING YET
ANOTHER PERIOD OF COLD AND DRY WEATHER. SOME SUGGESTION ON THE 00Z
MODELS THAT A LOW FORMING ALONG THE DEPARTING COLD FRONT COULD TRACK
FAR ENOUGH NORTH TO BRING A CHC OF PCPN TO THE AREA LATER THURSDAY.
NOT SURE IF THE HIGH WINS OUT WITH THIS...AND KEEPS THE LOW
SUPPRESSED ENOUGH TO THE SOUTH...SO WILL PLAY CONSERVATIVE AND STAY
DRY FOR NOW INTO FRIDAY. SOME GREAT MODEL DIVERGENCE FOR THE COMING
WEEKEND IN THE HANDLING OF A DEVELOPMENT OF THE NEXT POTENTIAL LOW
PRESSURE SYSTEM. PREVIOUS RUNS HAD BROUGHT IN A GOOD AMT OF
PCPN...WITH THE LATEST MODEL SUITE NOW KEEPING THINGS DRIER. WILL
HOLD WITH BLEND OF WPC/PREVIOUS FORECAST POPS FOR NOW UNTIL THERE IS
BETTER HANDLE OF THE SYNOPTIC FEATURES. THE HIGH FOR THE LATTER HALF
OF THE WEEK WILL KEEP A COLD AIRMASS IN PLACE...RESULTING IN TEMPS
STAYING BELOW NORMAL...WITH POSSIBLE WIND CHILL ISSUES...MAINLY IN
WESTERN AREAS EVERY NIGHT HEADING INTO THE WEEKEND.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
LOW-LEVEL MOISTURE REMAINS TRAPPED UNDERNEATH THE INVERSION EARLY
THIS MORNING. THEREFORE...IFR CIGS ARE EXPECTED ACROSS MOST
LOCATIONS. HOWEVER...DRIER AIR WILL WORK ITS WAY INTO THE AREA
BEHIND A COLD FRONT LATER THIS MORNING AND AFTERNOON. CIGS/VSBYS
SHOULD IMPROVE. HOWEVER...A BROKEN CU DECK MAY CAUSE A PERIOD OF
MVFR CIGS THIS AFTERNOON. LIGHT AND VARIABLE WINDS THIS MORNING WILL
TURN TOWARD THE NORTHWEST AROUND 5 TO 10 KNOTS THIS AFTERNOON.

THE NORTHWEST FLOW WILL CONTINUE TONIGHT AHEAD OF BUILDING HIGH
PRESSURE. VFR CONDITIONS ARE EXPECTED. WINDS WILL INCREASE TOWARD
SUNRISE AS THE PRESSURE GRADIENT INCREASES AHEAD OF THE BUILDING
HIGH. GUSTS AROUND 20 KNOTS ARE POSSIBLE.

GENERALLY VFR CONDITIONS THROUGH THE COMING WEEK. SUB-VFR CONDITIONS
POSSIBLE WITH ANY SNOW TUES NIGHT-WED.

NW GUSTS TO 20 KTS PSBL MONDAY...AND THEN AGAIN WEDNESDAY BEHIND
THE FRONT.

&&

.MARINE...
NO MARINE HEADLINES ARE EXPECTED TODAY. NORTHWEST WINDS WILL DEVELOP
LATER THIS MORNING AND AFTERNOON. NORTHWEST WINDS WILL INCREASE
TONIGHT AS THE PRESSURE GRADIENT INCREASES AHEAD OF BUILDING HIGH
PRESSURE. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS LATE
TONIGHT.

SOLID SCA CONDITIONS ON ALL WATERS THROUGH MONDAY...LINGERING ON THE
CHESAPEAKE BAY WATERS THROUGH MONDAY EVENING. SUB-SCA CONDITIONS
THEN FOR THE SECOND HALF OF THE NIGHT LASTING THROUGH TUES NIGHT.
PSBL SCA CONDITIONS RETURN BEHIND THE NEXT COLD FRONT WED WITH GUSTS
UP TO 20 KTS LASTING INTO THURS. SUB-SCA CONDITIONS RETURN BY
FRIDAY.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WINTER STORM WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR
     DCZ001.
MD...WINTER STORM WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR
     MDZ003>006-011-013-014-501>508.
     WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
     MDZ016>018.
VA...WINTER STORM WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR
     VAZ025>031-036>040-050>054-501>508.
     WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
     VAZ055>057.
WV...WINTER STORM WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR
     WVZ050>053-055-501>506.
MARINE...SMALL CRAFT ADVISORY FROM 1 AM TO 6 PM EST MONDAY FOR
     ANZ530>543.

&&

$$
SYNOPSIS...BJL
NEAR TERM...BJL
SHORT TERM...SEARS
LONG TERM...SEARS
AVIATION...BJL/SEARS
MARINE...BJL/SEARS







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