Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 312003 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 303 PM EST SAT JAN 31 2015 .SYNOPSIS... HIGH PRESSURE BUILDS ACROSS THE REGION THROUGH TONIGHT. 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. && .NEAR TERM /TONIGHT/... HIGH PRES OVR THE AREA THIS EVE WL ALLOW TEMPS TO DROP OFF QUICKLY AS WINDS BECOME LGT. TEMPS SHOULD DROP INTO THE 20S...AND THEN CLDS SHOULD OVRSPEAD THE AREA AHEAD OF LOW PRES WHICH WL BE MOVING INTO THE MID-MS VLLY. IT IS PSBL THAT TOWARD DAYBRK A BRIEF PD OF LGT SN A COUPLE FORM OVR THE NRN VA TO THE M-D LN...BUT THIS IS NOT XPCTD TO PRODUCE ANY ACCUMULATION. && .SHORT TERM /SUNDAY/... THE SUN/SUN NGT PART OF THE FCST HAS PROVED CHALLENING OVR THE PAST FEW DAYS. AFTR THAT BRF ERLY MRNG SN IT IS PSBL THAT A LARGE PORTION OF THE DAY WL BE DRY E OF THE MTNS...HOWEVER WL HV CHC POPS FOR RA IN THE CENTRAL SHEN VLLY...WINTRY MIX IN THE DC/BALT AREA. FURTHER W POPS ARE HIGHER. LGT ACCUMS ARE PSBL DURG THE AFTN IN WRN MD/PORTIONS OF ERN W.V. HIGHS SUN RANGING FM M40S IN THE CENTRAL SHEN VLLY TO THE LM30S ALONG THE PA BRDR. DC PROPER SHOULD REACH THE L40S...DOWNTOWN BALT U30S. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... 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 /19Z SATURDAY THROUGH THURSDAY/... VFR CONDS TNGT. CLDS WL BE ON THE INCRS LATE TNGT...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 CROSS THE AREA. MIXED PRECIP DURING THE EVENING WILL TRANSITION TO RAIN OVERNIGHT AT MOST OF THE TERMINALS. LOWEST CONFIDENCE ON PRECIP-TYPE IS AT MRB/IAD/BWI. 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. && .MARINE... WINDS CONT TO GUST TO A20 KT...SCA IN EFFECT THRU 6 PM. NO PROBS ON THE WATERS OVRNGT. 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. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ530>543. && $$ PRODUCTS...WOODY!/ADS/KLW

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