Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
727 FXUS61 KLWX 071953 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 253 PM EST SUN FEB 7 2016 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVERHEAD THROUGH TONIGHT WHILE COASTAL LOW PRESSURE PASSES BY WELL TO OUR SOUTH AND EAST. ANOTHER LOW PRESSURE SYSTEM WILL DIVE SOUTH INTO THE OHIO VALLEY MONDAY BEFORE PASSING THROUGH OUR AREA MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE WILL SLOWLY BUILD TOWARD OUR AREA DURING THE MIDDLE PORTION OF NEXT WEEK. && .NEAR TERM /THROUGH MONDAY/... HIGH PRESSURE IS LOCATED ACROSS THE REGION THIS AFTERNOON WHILE A COASTAL LOW INTENSIFYS OFF THE CAROLINAS. LIGHT NORTHERLY FLOW WILL CONTINUE AS THE COASTAL LOW MOVES ALONG THE GULF STREAM AND EVENTUALLY OUT TO SEA. MID-HIGH LEVEL CLOUDS ARE EXPECTED THROUGH TONIGHT. A BRIEF PERIOD OF UPPER LEVEL RIDGING WILL OCCUR OVERNIGHT BEFORE A BROAD AREA OF LOW PRESSURE ALOFT MOVES INTO THE OHIO VALLEY. HEIGHTS WILL BEGIN TO FALL LATE TONIGHT AND INTO MONDAY. A COLD FRONT WILL CROSS THE APPALACHAINS MONDAY AND PRECIPITATION WILL MOVE WEST TO EAST THROUGH THE AFTERNOON- EVENING AS SNOW IN THE MTNS AND RAIN IN THE LOW LANDS. TEMPS WILL REACH THE 40S IN THE LOW LANDS BY MONDAY EVENING. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... AS THE SUNSETS MONDAY NIGHT AND LOW PRESSURE FORMS OFF THE MID- ATLANTIC COAST RAIN WILL TRANSITION TO SNOW OVERNIGHT AND INTO TUESDAY MORNING. THERMAL PROFILES ACROSS THE REGION WITH THE EXCEPTION OF HIGHER ELEVATIONS WILL LIMIT SNOWFALL ACCUMULATION WHEN SNOW BEGINS MONDAY NIGHT INTO TUESDAY MORNING. AS TEMPS BEGIN TO RISE TUESDAY IN THE LOW LANDS AND EAST OF THE BLUE RIDGE SNOWFALL WILL BE DIFFICULT TO ACCUMULATE UNLESS BANDING OCCURS ACROSS THE REGION. AS STATED MANY TIMES WITH THIS SYSTEM...MOISTURE AND QPF FIELDS DIFFER IN MODEL GUIDANCE AS MOST OF THE BANDING ACTIVITY WILL BE CONVECTIVE IN NATURE. THE STRONG 925- 850MB EASTERLY JET ONCE THE SFC LOW FORMS ALONG THE COAST WILL ALLOW INSTABILITY TO INCREASE AND SNOWFALL RATES TO INCREASE. AT THIS TIME LOCATION AND EXACT TIMING OF THESE INSTABILITY BANDS ARE UNCERTAIN BUT THE BEST TIMING WILL BE TUESDAY MORNING INTO TUESDAY EVENING. THE SNOWFALL ACCUMULATION FORECAST IS THERMALLY BASED WITH SNOWFALL TOTALS HIGHER WHERE BOUNDARY LAYER CONDITIONS ARE COLDER FOR SNOW SUCH AS NEAR THE MD/PA BORDER...HIGHER ELEVATIONS AND THE WESTERN SLOPES OF THE ALLEGHENY FRONT. FURTHER SOUTH AND EAST...TEMPS WILL REACH THE MID TO UPPER 30S TUESDAY AND SNOWFALL WILL LIKELY ACCUMULATE AND MELT AND DRIER AIR WILL LIKELY MOVE INTO CENTRAL VA TUESDAY. ACCUMULATIONS OF 3-6 INCHES EXPECTED ACROSS THE NRN HALF OF THE MID-ATLANTIC AND 1-3 IN THE SOUTHERN HALF WITH HIGHER AMTS ALONG THE RIDGES. THE BROAD UPPER LEVEL TROUGH WILL STAY ACROSS THE AREA INTO WEDNESDAY AND SCATTERED SNOW SHOWERS WILL BE POSSIBLE. LIGHT ACCUMULATION IS POSSIBLE ACROSS THE REGION. SNOW SHOWERS ARE EXPECTED ACROSS THE WESTERN SLOPES OF THE ALLEGHENY FRONT AS NW WINDS CONTINUE TO DRAW DOWN MOISTURE FROM THE GREAT LAKES. ACCUMULATING SNOWFALL IS EXPECTED THROUGH THURSDAY FOR THIS AREA WITH TOTAL SNOWFALL ACCUMULATION OF 6-8 INCHES. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... THE MAIN UPPER LEVEL TROUGH OF LOW PRESSURE WILL PIVOT ACROSS THE REGION LATER IN THE DAY WEDNESDAY INTO WEDNESDAY NIGHT. ADDITIONAL UPSLOPE SNOW EXPECTED IN THE POTOMAC HIGHLANDS...WHILE AN OCCASIONAL SNOW SHOWER OR TWO CANNOT BE RULED OUT ACROSS THE I-81 AND I-95 CORRIDORS. MUCH COLDER AIR WILL BE ON THE HEELS OF THIS UPPER TROUGH WEDNESDAY NIGHT AS A COLD DOME OF HIGH PRESSURE BUILDS IN FROM THE WEST. HIGH PRESSURE WILL DOMINATE THURSDAY AND THURSDAY NIGHT WITH VERY COLD AND DRY AIR ACROSS THE REGION. TEMPERATURES WILL BE 10 TO 15 DEGREES BELOW NORMAL. AS THE HIGH FLATTENS OUT LATE THURSDAY NIGHT INTO FRIDAY...AN AREA OF LOW PRESSURE SHOULD SCOOT ACROSS THE TENNESSEE VALLEY. THIS LOW SHOULD JUST SPREAD ADDITIONAL CLOUD COVER ACROSS THE SOUTHERN HALF OF OUR REGION. A BRIEF PERIOD OF LIGHT SNOW CANNOT BE RULED OUT ACROSS THE VIRGINIA PIEDMONT TO THE MOUTH OF THE CHESAPEAKE BAY. VERY COLD TEMPERATURES WILL CONTINUE FRIDAY INTO FRIDAY NIGHT WITH TEMPERATURES ABOUT 10 TO 15 DEGREES BELOW NORMAL. BEHIND THE AREA OF LOW PRESSURE...THE MAIN UPPER LEVEL TROUGH OF SUPPORT WILL PIVOT EAST WITH A FIRM RIDGE OF HIGH PRESSURE QUICKLY TO FOLLOW IT. ASIDE FROM DIURNAL CLOUD COVER SATURDAY...THIS TROUGH WILL MAINLY SUPPORT ARCTIC AIR SURGING INTO THE MID ATLANTIC SATURDAY AND SATURDAY NIGHT. THE SAME RIDGE OF HIGH PRESSURE BUILDING INTO THE REGION WILL BECOME REENFORCED SUNDAY INTO SUNDAY NIGHT. THUS...HIGH AND LOW TEMPERATURES WILL REMAIN WELL BELOW NORMAL WITH THE POTENTIAL OF EXPERIENCING LOWS IN THE SINGLE DIGITS BELOW ZERO TO HIGHS IN THE TEENS ACROSS A LARGE PORTION OF THE REGION. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... VFR CONDITIONS EXPECTED THROUGH MONDAY AFTERNOON. LOW CIGS ARE EXPECTED TO FORM AT DCA/BWI/MTN MONDAY AFTERNOON BEFORE MOVING ACROSS ALL THE TERMINALS MONDAY NIGHT. SN/RA IS EXPECTED LATE MONDAY AFTERNOON INTO THE EVENING BEFORE CHANGING TO ALL SN BY MID-NIGHT. FLIGHT RESTRICTIONS ARE EXPECTED FOR VSBYS/CIGS. PREVAILING -SN IS EXPECTED THROUGH TUESDAY NIGHT WITH THE POSSIBILITY OF PERIODS OF +SN ACROSS MRB/BWI/MTN. -SNSH POSSIBLE WEDNESDAY AS UPPER LEVEL TROUGH CONTINUES TO MOVE OVERHEAD. PREVAILING VFR CONDITIONS EXPECTED WEDNESDAY. MVFR CONDITIONS WEDNESDAY WITH A CHANCE OF SNOW SHOWERS AT ANY TERMINALS. WINDS WEST TO WEST-NORTHWEST 5 TO 10 KNOTS GUSTS 15 KNOTS WEDNESDAY. VFR CONDITIONS WEDNESDAY NIGHT. WINDS WEST-NORTHWEST 5 TO 10 KNOTS GUSTS 15 KNOTS. && .MARINE... A COASTAL LOW WILL MOVE TO THE SOUTH AND EAST TODAY AND TONIGHT. NRLY WINDS WILL INCREASE LATE THIS AFTERNOON AND EVENING AND A SCA IS IN EFFECT FOR AREAS SOUTH OF SANDY POINT AND THE LOWER TIDAL POTOMAC. WINDS WILL DIMINSH TUESDAY AS THE COASTAL LOW MOVES OUT TO SEA. RAIN AND SNOW SHOWERS ARE EXPECTED MONDAY NIGHT THROUGH TUESDAY FOR THE WATERS. NORTHWEST WINDS WILL INCREASE TUESDAY AFTERNOON AND CONTINUE THROUGH THE END OF THE WEEK. AT THIS TIME MARINE HEADLINES ARE NOT EXPECTED. SMALL CRAFT ADVISORIES POSSIBLE WEDNESDAY. WINDS WEST BECOMING NORTHWEST 10 TO 15 KNOTS GUSTS 20 KNOTS. SMALL CRAFT ADVISORIES LIKELY WEDNESDAY NIGHT. WINDS NORTHWEST 15 TO 20 KNOTS GUSTS 25 TO 30 KNOTS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 9 AM EST MONDAY FOR ANZ532-533-540-541. SMALL CRAFT ADVISORY UNTIL 9 AM EST MONDAY FOR ANZ534-537-543. && $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...HAS LONG TERM...KLW AVIATION...HAS/KLW MARINE...HAS/KLW

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.