Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 010230 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 930 PM EST SAT JAN 31 2015 .SYNOPSIS...
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HIGH PRESSURE BUILDS ACROSS THE REGION OVERNIGHT. LOW PRESSURE WILL APPROACH FROM THE WEST SUNDAY...CROSSING THE REGION SUNDAY NIGHT. HIGH PRESSURE WILL RETURN FOR THE FIRST HALF OF THE WEEK. A COLD FRONT IS EXPECTED TO MOVE INTO THE REGION THURSDAY.
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&& .NEAR TERM /THROUGH SUNDAY/...
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...WINTER WEATHER ADVISORY ISSUED FOR N AND W MARYLAND SUN-MON... NEAR TERM FORECAST REMAINS ON TRACK WITH LITTLE CHANGE. COLD DOME OF HIGH PRESSURE WILL REMAIN OVER THE REGION TONIGHT. MOSTLY CLEAR SKIES COMBINED WITH LIGHT WINDS WILL KEEP TEMPERATURES COLD OVERNIGHT. READINGS AS OF 02Z HAVE ALREADY DIPPED BACK INTO THE UPPER TEENS TO 20S IN MOST LOCATIONS. TEMPS WILL FALL OFF A LITTLE FURTHER UNTIL CLOUD COVER INCREASES FROM WEST TO EAST TONIGHT. EXPECTING OVERCAST CONDITIONS BY DAYBREAK SUNDAY. ON SUNDAY...SURFACE LOW PRESSURE APPROACHES FROM THE WEST AND WARM AIR ADVECTION WILL BEGIN TO OVERRUN THE COLD SURFACE TEMPERATURES. VERY LIGHT PRECIPITATION IS EXPECTED TO DEVELOP MAINLY OVER THE NORTHERN AND WESTERN SECTIONS AROUND MIDDAY WITH COVERAGE INCREASING AS THE DAY GOES ON. THE BULK OF THE PRECIPITATION IS EXPECTED TO OCCUR SUNDAY NIGHT INTO MONDAY MORNING. PRECIPITATION TYPE IS STILL A CHALLENGE FOR TOMORROW AS WARM AIR OVERRIDES A SHALLOW COLD AIRMASS. A WINTRY MIX IS EXPECTED ALMOST EVERYWHERE AT THE ONSET. THE PRECIPITATION WILL MIX WITH AND CHANGE TO RAIN FROM WASHINGTON DC AND POINTS SOUTH BY EARLY EVENING. THE FAR N AND W SUBURBS OF BALTIMORE AND WASHINGTON DC WILL HOLD ONTO A WINTRY MIX A BIT LONGER. OUR HIGHEST CONFIDENCE FOR AN EXTENDED PERIOD OF SNOW...SLEET AND FREEZING RAIN IS OVER NORTHERN AND WESTERN MARYLAND. A WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR THESE LOCATIONS. SLIPPERY TRAVEL FROM SNOW AND ICY CONDITIONS ARE MOST LIKELY IN THESE LOCATIONS. IF THE COLDER AIR REMAINS IN PLACE LONGER...THE ADVISORY MAY NEED TO BE EXPANDED FURTHER SOUTH.
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&& .SHORT TERM /SUNDAY NIGHT/...
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WINTRY MIX CHANGES TO FREEZING RAIN OVER THE NORTHERN MOST PORTION OF THE FORECAST AREA WITH RAIN EXPECTED FROM THE METRO AREAS AND POINTS SOUTH. OVERNIGHT TEMPERATURES NEAR FREEZING NORTH TO THE MIDDLE TO UPPER 30S SOUTH ARE EXPECTED.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/... SFC LOW WILL BE CROSSING THE AREA SUNDAY NIGHT...PROVIDING THE BEST SOURCE OF WIDESPREAD PRECIP. STILL SOME SPREAD ON THE EXACT TRACK OF THE LOW AS NORTHERN AND SOUTHERN STREAM ENERGY BEGIN INTERACTING. CONSENSUS TRACK LIES ACROSS THE NORTHERN PART OF THE CWA...ALTHOUGH THERE ARE SOME MUCH FARTHER NORTH SOLUTIONS IN THE SUITE. RELIED ON A NAM/ECMWF BLEND FOR THE FORECAST AS THEIR THERMAL FIELDS ALLOW A STAIR STEP FROM PREVIOUS FORECASTS AND ALLOW FOR THE POTENTIAL OF MIXED PRECIP ALONG THE M-D LINE. LLJ WILL INCREASE AHEAD OF THE STRENGTHENING LOW PRESSURE SYSTEM. THIS WILL DRAW COPIOUS MOISTURE INTO THE REGION AS WELL AS WARMTH. STILL LOW CONFIDENCE ON HOW THIS TRANSLATES TO THE SFC. W-E LOW TRACK AND LACK OF CAD HIGH TO THE NORTHEAST NOT FAVORABLE FOR LOCKING COLD AIR IN...BUT DIURNAL TIMING AND IN-SITU PROCESSES MAY MAKE IT HARD TO WARM UP AS MUCH AS SOME OF THE MODELS PREDICT. A MIX OF PRECIP IN THE EVENING WILL BECOME MORE LIQUID WITH THE WAA ALOFT. KEPT TEMPS AT OR JUST BELOW FREEZING IN THE MOST CLIMATOLOGICALLY FAVORED AREAS...ALTHOUGH THIS MAY STILL BE A LITTLE TOO GENEROUS...AND DOES NOT TAKE INTO CONSIDERATIONS HOW PAVEMENT TEMPERATURES RESPOND. CERTAINLY AN AREA OF THE FORECAST TO MONITOR. ACCUMULATING SNOW FROM LATE AFTERNOON-EVENING NOW SCALED BACK TO 1-3 INCHES IN THE NORTH...AND THIS COULD STILL BE GENEROUS DEPENDING ON THE LOW TRACK. ICING AMOUNTS EXPECTED TO BE LIGHT WITH NEAR-FREEZING TEMPS. FRONT EXPECTED TO PUSH EASTWARD WITH THE LOW MONDAY MORNING OR AFTERNOON. THINK FOR THE MOST PART DRIER AIR WILL ARRIVE BEFORE A CHANGEOVER TO SNOW WILL OCCUR...WITH THE EXCEPTION BEING IN NORTHERN MD. TEMPERATURES WILL FALL BEHIND THE FRONT DURING THE AFTERNOON AND WINDS WILL INCREASE. THERE WILL BE A PERIOD OF UPSLOPE SNOW WITH A FEW INCHES POSSIBLE. THESE SNOW WILL COME TO AN END MONDAY EVENING AS DRIER AIR AND HIGH PRESSURE BUILDS IN FROM THE WEST. THIS HIGH WILL ALSO USHER IN AN ARCTIC AIRMASS WITH TEMPERATURES DROPPING INTO THE TEENS AND SOME SINGLE DIGITS. HIGH PRESSURE WILL DOMINATE THE REGION TUESDAY AND TUESDAY NIGHT...BRINGING DRY CONDITIONS AND LIGHT AND VARIABLE WINDS. DESPITE SOME SUNSHINE TUESDAY...TEMPERATURES WILL REMAIN NEARLY 10 DEGREES BELOW NORMAL. A COLD FRONT WILL MOVE ACROSS THE REGION WEDNESDAY AND WEDNESDAY NIGHT. THERE IS A CHANCE OF SNOW WEDNESDAY NIGHT INTO THURSDAY ON THE COLD SIDE OF THE FRONT WITH THE ONSET POSSIBLY MIXING WITH A LITTLE RAIN WEDNESDAY EVENING. TEMPERATURES WILL NOT BE AS COLD WEDNESDAY AND WEDNESDAY NIGHT. TEMPERATURES THURSDAY THROUGH FRIDAY WILL TAKE ANOTHER PLUNGE TO 10 TO 15 DEGREES BELOW NORMAL AS A COLD DOME OF HIGH PRESSURE BUILDS IN TO THE NORTH OF THE DEPARTING COLD FRONT. DRY CONDITIONS WILL PERSIST THROUGH THE PERIOD. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/...
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CLDS WL BE ON THE INCRS OVERNIGHT...PSBLY DROPPING INTO LIFR DURG DAY. LGT SN PSBL ARND 12Z IAD/DCA AND N...THEN A CHC OF R/IP DURG THE AFTN. IFR LIKELY SUNDAY NIGHT AS LOW PRESSURE CROSSES THE AREA. MIXED PRECIP DURING THE EVENING WILL TRANSITION TO RAIN OVERNIGHT AT MOST OF THE TERMINALS EXCEPT KMRB. COLD FRONT PASSES MONDAY MORNING AND IMPROVES CONDITIONS BUT INTRODUCES STRONG NW WINDS THROUGH AFTERNOON/EVENING. VFR CONDITIONS TUESDAY THROUGH WEDNESDAY. WINDS NW 10 KNOTS TUESDAY DIMINISHING LIGHT AND SOUTHERLY 5 TO 10 KNOTS TUESDAY NIGHT. WINDS S BECOMING W 5 TO 10 KNOTS WEDNESDAY.
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&& .MARINE...
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WINDS WILL REMAIN BELOW SCA CRITIERIA OVERNIGHT. LOW PRESSURE TRACKS JUST NORTH OF THE WATERS LATE SUNDAY NIGHT WITH A COLD FRONTAL PASSAGE MONDAY MORNING. RAIN WILL BE PREDOMINANT PRECIP TYPE OVER THE WATERS. STRONG NW WINDS BEHIND THE FRONT...MAY BE IN THE GALE CATEGORY. WINDS DECREASE LATE MONDAY NIGHT. NO MARINE HAZARDS EXPECTED TUESDAY THROUGH WEDNESDAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...WINTER WEATHER ADVISORY FROM NOON SUNDAY TO 8 AM EST MONDAY FOR MDZ003-501-502. WINTER WEATHER ADVISORY FROM 3 PM SUNDAY TO 8 AM EST MONDAY FOR MDZ004>006-507. VA...NONE. WV...WINTER WEATHER ADVISORY FROM NOON SUNDAY TO 8 AM EST MONDAY FOR WVZ051-052. MARINE...NONE.
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&& $$ SYNOPSIS...KRW NEAR TERM...KRW SHORT TERM...ADS/KRW/ABW LONG TERM...ADS AVIATION...ADS/KRW MARINE...ADS/KRW

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