Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 020858 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 358 AM EST MON MAR 2 2015 .SYNOPSIS... A COLD FRONT WILL PUSH EAST OF THE AREA TODAY. HIGH PRESSURE THEN WILL BUILD IN THROUGH TUESDAY. A WARM FRONT WILL CROSS THE AREA TUESDAY NIGHT. A STRONG COLD FRONT WILL CROSS THE REGION LATE WEDNESDAY AS COLD HIGH PRESSURE BUILDS IN FOR THURSDAY AND CONTINUES INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A COLD FRONT IS LOCATED ALONG THE ALLEGHENY FRONT THIS MORNING WHILE HIGH PRESSURE RESIDES ACROSS THE REGION. LOW CLOUDS AND FOG WILL PERSIST EAST OF THE BLUE RIDGE AS LOW LEVEL MOISTURE IS TRAPPED UNDER THE INVERSION. SURFACE TEMPS HAVE ONLY FLUCTUATED 1-2 DEGREES FROM THIS PAST EVENING AND ARE HOVERING FREEZING FOR MOST OF THE REGION. THIS HAS LED TO ICY CONDITIONS OVERNIGHT DUE TO THE RESIDUAL ICE FROM SUNDAY. PATCHY FOG MAY ALSO LEAD TO SLICK SPOTS THIS MORNING. USE CAUTION DURING THE MORNING COMMUTE TODAY. THE COLD FRONT WILL CONTINUE TO MAKE A EASTWARD TREK ACROSS THE MID- ATLANTIC. IT IS EXPECTED TO BE EAST OF I-95 BY MID MORNING. DRY N-NW FLOW BEHIND THE FRONT WILL MIX OUT THE LOW LEVEL MOISTURE. CLEARING WILL ALSO OCCUR FROM WEST TO EAST TODAY. HIGH TEMPS TODAY WILL LIKELY BE REACHED AROUND NOON AS MIXING BRINGS DOWN COLDER AIR THIS AFTERNOON AND TEMPS START TO DROP. SUNSHINE AND DOWNSLOPING WILL HELP RISE TEMPS TODAY BUT ONLY TO THE LOW TO MID 30S ACROSS NRN MD TO THE UPPER 30S AND AROUND 40 DEGREES ACROSS THE FOOTHILLS AND PIEDMONT. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... CLEARING WILL CONTINUE TONIGHT AS HIGH PRESSURE MOVES IN FROM THE MID-WEST. TEMPERATURES ARE EXPECTED TO DROP INTO UPPER TEENS TO LOW 20S ACROSS NRN MARYLAND TO THE MID TO UPPER 20S ACROSS CENTRAL VA. CLOUDS WILL INCREASE FROM THE SOUTHWEST TOWARDS TUESDAY MORNING AS THE NEXT SYSTEMS APPROACHES THE REGION. HIGH PRESSURE WILL BE LOCKED IN PLACE AT THE SURFACE WHILE WARM ADVECTION HEADS TOWARDS THE MID- ATLANTIC. SIMILAR TO SUNDAY...WARM AIR ADVECTION WILL LEAD TO PRECIPITATION TO MOVE INTO THE REGION FROM THE SW. PRECIPITATION IS EXPECTED TO BEGIN AS SNOW BEFORE QUICKLY CHANGING TO IP/FZRA BY TUESDAY AFTERNOON. FCST MAX TEMPS FOR TUESDAY RANGE FROM THE LOW 30S IN NE MD TO THE MID 30S EAST OF THE BLUE RIDGE. FURTHER WEST...TEMPS SHOULD RISE ABOVE FREEZING IN THE SHENANDOAH VALLEY AND HIGHER ELEVATIONS. LESS THAN A TENTH INCH OF ICE IS EXPECTED TUESDAY AFTERNOON FOR AREAS EAST OF THE BLUE RIDGE. CONFIDENCE IS LOW FOR AREAS ACROSS THE PIEDMONT AND SOUTHERN MD WHERE TEMPS MAY REACH THE MID 30S. THE MIDDLE PORTION OF THE WEEK WILL BE VERY ACTIVE WITH SUBSTANTIAL SWINGS IN THE WEATHER. WHAT HAPPENS TUESDAY EVENING MAY BE DEPENDENT ON HOW MUCH TEMPERATURES CAN WARM ON TUESDAY. STRONG WAA WILL BE TAKING PLACE ALOFT...BUT AS USUAL THE QUESTION IS HOW MUCH TRANSLATES TO THE SFC...ESPECIALLY IN AREAS WHERE THE COLDER AIR IS WEDGED IN. BY TUESDAY EVENING THIS MAY ONLY BE IN THE MOST FAVORED AREAS ADJACENT TO THE NORTHERN BLUE RIDGE AND ACROSS NORTHERN MD. LEFT RA-OR-FZRA WORDING IN THESE AREAS FOR THE EVENING. CURRENT FORECAST CALLS FOR WARM AIR TO WIN OUT WITH RISING TEMPERATURES OVERNIGHT...BUT THIS IS FAR FROM CERTAIN IN THE AREAS MENTIONED ABOVE. ON THE OTHER HAND...THE HIGHER ELEVATIONS COULD BE NEAR 50F OR GREATER BY DAYBREAK. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AREA STILL FORECAST TO REMAIN IN THE WARM SECTOR ON WED WITH HIGHS INTO THE 50S EXCEPT N-CNTL/NE MD. SHOWERS WILL BE LIKELY THROUGHOUT THE DAY IN A BROAD AREA OF MOIST ASCENT. HOWEVER IT LOOKS LIKE THE GREATER MOISTURE MAY REMAIN SW OF THE AREA THROUGH THIS TIME...WHICH WOULD REDUCE THE THREAT FOR ANY FLOODING. WED NIGHT/THU FORECAST IS QUITE UNCERTAIN AS A COLD FRONT SLOWLY SLIPS THROUGH THE AREA. IT WILL BE NEARLY PARALLEL TO A STRONG UPPER JET...DENOTING THE TIGHT LOW LEVEL BAROCLINIC ZONE. AT LEAST ONE WAVE OF LOW PRESSURE IS FORECAST TO TRACK ALONG THE FRONT...WHICH COULD OCCUR AFTER COLDER AIR BEGINS TO PUSH INTO THE AREA. HAVE BROADBRUSHED RA/SN WORDING BASED ON FORECAST TEMPS. A LOT OF MOISTURE WILL BE IN PLAY IN THE FRONTAL ZONE...WHICH COULD PRESENT ACCUMULATING SNOW. AGREE WITH WPC GUIDANCE THAT THE BEST CHANCE FOR SNOW ACCUMULATIONS WILL BE N/W OF DC...WITH THE HIGHEST AMOUNTS IN THE WV MOUNTAINS. CERTAINLY A SITUATION TO MONITOR. ARCTIC HIGH PRESSURE WORKS IN FULLY BY THU NIGHT...WITH LOWS DROPPING INTO THE TEENS AND SINGLE DIGITS. THE HIGH WILL SLOWLY MOVE EAST ACROSS THE AREA THROUGH SATURDAY. EXPECT GRADUALLY MODERATING TEMPERATURES...PERHAPS PUSHING CLIMO BY SATURDAY AND SUNDAY. A MOISTURE STARVED COLD FRONT MAY APPROACH LATE IN THE WEEKEND. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... LIFR/VLIFR CONDITIONS EXPECTED THROUGH SUNRISE THIS MORNING AS FOG AND LOW STRATUS CONTINUE. A COLD FRONT WILL MOVE THROUGH THE REGION THIS MORNING AND MOISTURE SHOULD DISSIPATE FROM WEST TO EAST BY 9AM. VFR CONDITIONS EXPECTED THIS AFTERNOON WITH WINDS BECOMING NW 10- 15KTS G 20-25 KTS. WINDS WILL SUBSIDE TONIGHT AND VFR CONDITIONS WILL CONTINUE THROUGH TONIGHT. HIGH PRESSURE BUILDS INTO THE REGION TUESDAY BUT MOISTURE WILL MOVE IN FROM THE SW. -SNPL BECOMING FZRA WILL IMPACT THE TERMINALS BY TUESDAY AFTERNOON. BEST CHANCE FOR ICE ACCUMULATION WILL BE AT BWI-MTN. VSBY/CIG REDUCTIONS WILL CONTINUE TUESDAY NIGHT THROUGH WEDNESDAY WITH RAIN AT TIMES. GUSTY SOUTHERLY WINDS ALSO EXPECTED ON WEDNESDAY. RAIN MAY CHANGE TO SNOW FOR PORTIONS OF THE AREA WEDNESDAY NIGHT-THURSDAY...WHICH WOULD LEAD TO SUB-VFR CONDITIONS. && .MARINE... WINDS WILL SHIFT TO THE NORTHWEST BY MID MORNING BEHIND A COLD FRONT. A SMALL CRAFT ADVISORY IS IN EFFECT MONDAY FOR NORTHWEST WINDS GUSTING AROUND 20 TO 25 KNOTS. SCA CONDITIONS WILL BE POSSIBLE TUESDAY NIGHT INTO WEDNESDAY AHEAD OF AN APPROACHING COLD FRONT...AND AGAIN LATE WEDNESDAY NIGHT INTO THURSDAY AS COLD AIR PUSHES IN BEHIND THE FRONT. && .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...NONE. MD...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR MDZ501. VA...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR VAZ503. WV...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR WVZ501-503-505. MARINE...SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 6 PM EST THIS EVENING FOR ANZ530>543. && $$ SYNOPSIS...ADS NEAR TERM...HAS SHORT TERM...ADS/HAS LONG TERM...ADS AVIATION...ADS/HAS MARINE...ADS/HAS HYDROLOGY...JCE

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