Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 061431 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 931 AM EST SAT FEB 6 2016 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVERHEAD TODAY. COASTAL LOW PRESSURE WILL PASS BY WELL TO THE SOUTH AND EAST LATE TONIGHT THROUGH SUNDAY. 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 TONIGHT/...
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HIGH PRESSURE IS ACROSS THE REGION THIS MORNING. TEMPS WILL SLOWLY CLIMB INTO THE 40S TODAY. PREVIOUS DISCUSSSION... SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION TODAY...BRINGING DRY AND SEASONABLY CHILLY CONDITIONS. A LONGWAVE UPPER-LEVEL TROUGH WILL BUILD THROUGH THE OHIO VALLEY TODAY AND UPPER-LEVEL LOW PRESSURE IN THE SOUTHERN STREAM WILL STRENGTHEN OVER THE GULF COAST STATES. A POTENT JETMAX AROUND THIS UPPER-LEVEL LOW WILL MOVE INTO THE SOUTHEASTERN CONUS...AND OUR AREA WILL END UP CLOSE TO THE LEFT EXIT REGION OF THE JET. A BKN DECK OF HIGH CLOUDS ARE LIKELY AS A RESULT. SINCE THE CLOUD DECK WILL BE THIN THERE SHOULD BE BREAKS OF SUNSHINE...BUT PARTLY TO MOSTLY CLOUDY SKIES ARE EXPECTED. MAX TEMPS WILL RANGE FROM THE UPPER 20S AND LOWER 30S ALONG THE RIDGES TO THE LOWER AND MIDDLE 40S ACROSS MOST OTHER LOCATIONS. WEAK SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION TONIGHT. A BKN DECK OF HIGH CLOUDS WILL HANG AROUND THIS EVENING...BUT CLOUDS SHOULD THIN OUT AS THE JETMAX HEADS OUT TO SEA. THE COMBINATION OF MAINLY CLEAR SKIES LATE TONIGHT AND LIGHT WINDS WILL ALLOW FOR RADIATIONAL COOLING. MIN TEMPS WILL BE IN THE 20S ACROSS MOST LOCATIONS.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... LOW PRESSURE IN THE SOUTHERN STREAM WILL RAPIDLY INTENSIFY OFF THE SOUTHEAST COAST SUNDAY WHILE ANOTHER LOW DIGS SOUTH INTO THE GREAT LAKES. OUR AREA SHOULD REMAIN IN BETWEEN THESE TWO LOWS AND WEAK HIGH PRESSURE WILL PERSIST. THIS WILL KEEP THE AREA DRY AND SEASONABLY CHILLY...DESPITE SUNSHINE. THERE MAY BE SOME HIGH CLOUDS THAT MOVE INTO AREA WELL NORTH OF THE LOW OFF THE SOUTHEAST COAST...ESPECIALLY ACROSS SOUTHERN MARYLAND. THE STRONG LOW PRESSURE OFF THE SOUTHEASTERN CONUS WILL MOVE OUT TO SEA SUNDAY NIGHT WHILE ANOTHER LOW TRACKS THROUGH THE GREAT LAKES INTO THE OHIO VALLEY AND MIDWEST. AGAIN THE AREA WILL REMAIN IN BETWEEN THESE SYSTEMS...SO IT WILL BE DRY AND SEASONABLY CHILLY. A HIGH AMPLITUDE PATTERN SETS UP MONDAY THROUGH MONDAY NIGHT. AN UPPER-LEVEL RIDGE WILL BUILD OVER THE WESTERN CONUS WHILE A POTENT TROUGH AND UPPER-LEVEL LOW DIG SOUTH INTO THE OHIO AND TENNESSEE VALLEYS. THE SURFACE LOW ASSOCIATED WITH THIS SYSTEM OVER THE GREAT LAKES WILL TRANSFER ITS ENERGY INTO A COASTAL LOW LATER MONDAY/MONDAY NIGHT AS SHORTWAVE ENERGY AROUND THE UPPER-LEVEL LOW INTERACTS WITH THE BAROCLINIC ZONE ALONG THE MID-ATLANTIC COAST. A SURFACE TROUGH/OCCLUDED FRONT WILL EXTEND FROM THE LOW OVER THE GREAT LAKES SOUTHEAST NEAR OUR AREA TO THE LOW OVER THE MID-ATLANTIC COAST. AT THE SAME TIME...SHORTWAVE ENERGY WILL BE ROTATING AROUND THE UPPER-LEVEL LOW PASSING THROUGH OUR AREA. THESE MECHANISMS WILL LIKELY CAUSE PRECIPITATION TO DEVELOP OVER OUR AREA LATER MONDAY THROUGH MONDAY NIGHT. HOWEVER...DETAILS OF EXACTLY HOW MUCH PRECIPITATION AND HOW MUCH COLD AIR WILL BE IN PLACE REMAIN UNCERTAIN AT THIS TIME. THERE ARE TWO SCENARIOS. THE FIRST SCENARIO IS THAT THE UPPER- LEVEL LOW DOES NOT DIG FAR ENOUGH SOUTH FOR OUR AREA TO BE INFLUENCED BY THE SURFACE TROUGH/OCCLUDED FRONT. IN OTHER WORDS THAT SETS UP TO OUR NORTH. IF THIS OCCURS...THEN PRECIPITATION AMOUNTS WILL BE LIGHT AND LESS COLD AIR WILL FILTER IN FROM THE NORTH AND EAST...CAUSING THE PTYPE TO BE RAIN OR A MIX OF RAIN AND SNOW. THIS WOULD ALLOW FOR ONLY LIGHT SNOW ACCUMULATIONS IF ANY...AND MOST OF THE SNOW ACCUMULATION WOULD OCCUR OVER THE HIGHER TERRAIN. THE SECOND SCENARIO IS THAT THE UPPER-LEVEL LOW DIGS FARTHER SOUTH AND WE ARE IMPACTED BY THE SURFACE TROUGH/OCCLUDED FRONT. COLDER AIR IS ABLE TO FILTER IN FROM THE NORTH AND EAST ON THE COLD SIDE OF THE BOUNDARY...AND ATLANTIC MOISTURE WOULD ALSO WRAP AROUND INTO THIS SYSTEM DUE TO AN EASTERLY COMPONENT TO THE LOW-LEVEL FLOW. THIS WOULD CAUSE SIGNIFICANT SNOWFALL ACCUMULATIONS ACROSS MUCH OF THE AREA LATE MONDAY THROUGH MONDAY NIGHT. CONFIDENCE IN WHAT SCENARIO PLAYS OUT IS STILL UNCERTAIN AT THIS TIME. THE GEFS MEAN AND GFS DETERMINISTIC LEAN TOWARD SCENARIO 1 WHILE THE ECMWF ENSEMBLE MEAN AND THE DETERMINISTIC ECMWF LEAN TOWARD SCENARIO 2. THE NAM IS LEANING BETWEEN THE TWO SETS AND THE INDIVIDUAL GEFS MEMBERS ARE SPLIT AS WELL. THE LATEST FORECAST BLENDS MOST OF THESE SOLUTIONS TOGETHER...BUT DETAILS WILL HAVE TO BE FINE TUNED OVER THE NEXT COUPLE DAYS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... STILL SOME UNCERTAINTIES WITH THE 00Z MODEL SUITE ON THE HANDLING OF AN UPPER LVL TROUGH/CLOSED LOW PIVOTING THRU THE REGION BEGINNING MONDAY...BUT IMPACTING THE MID- ATLANTIC FOR A GOOD PORTION OF THE COMING WEEK. DEPENDING ON THE DEPTH OF THE TROUGH WILL DICTATE THE DEVELOPMENT OF THE SFC LOW OFF THE COAST THAT WILL BRING THE PCPN CHANCES TO THE CWA FOR TUES INTO WED. THE PLACEMENT WILL ALSO DETERMINE ANY ENHANCEMENT TO THE PCPN DEVELOPMENT FROM ENERGY ALOFT. AS SUCH...NOT MAKING TOO MANY CHANGES FROM THE PREVIOUS FORECAST AFTR 12Z TUES UNTIL THE MODELS COME INTO BETTER AGREEMENT. RAIN AND/OR SNOW WILL TURN TO SNOW SHOWERS IN THE WEST TUES...AND WILL LAST THRU WED WITH THE TROUGH OVERHEAD. AS OF NOW THE POTENTIAL EXISTS FOR THE SNOW SHOWERS TO SPREAD EAST OF THE BLUE RIDGE TUES NIGHT-WED...DRYING UP BY WED NIGHT AS THE SFC LOW EXITS THE REGION WITH HIGH PRESSURE BUILDING IN FROM THE WEST. NW FLOW AS THE HIGH BUILDS IN COULD POTENTIALLY KEEP SNOW SHOWERS ONGOING THRU THE END OF THE WEEK. 00Z MODEL SUITE TRENDING COOLER WITH THE TEMPS...WITH HIGHS EACH DAY IN THE 30/40S AND LOWS DROPPING INTO THE TEENS/20S. SOME BELOW ZERO WIND CHILLS WILL BE POSSIBLE POTOMAC HIGHLANDS WED NIGHT BUT ATTM NOT ANTICIPATING WIND CHILL ADVISORY CRITERIA TO BE MET. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS ARE EXPECTED THROUGH MIDDAY MONDAY. LOW PRESSURE WILL IMPACT THE TERMINALS LATER MONDAY THROUGH MONDAY NIGHT. DETAILS ARE UNCERTAIN...BUT WINTRY PRECIPITATION MAY LEAD TO SUBVFR CIGS AND VSBYS. SUB-VFR CONDITIONS PSBL TUES-WED WITH SNOW AND/OR RAIN. VFR CONDITIONS BY THURS LASTING INTO FRI. GUSTY W WINDS PSBL WED-FRI. && .MARINE... HIGH PRESSURE WILL REMAIN OVER THE WATERS THROUGH TONIGHT. POTENT LOW PRESSURE WILL PASS BY WELL TO THE SOUTH OF THE WATERS LATER SUNDAY THROUGH SUNDAY NIGHT. THE PRESSURE GRADIENT MAY BE STRONG ENOUGH FOR WINDS TO APPROACH SCA CRITERIA ACROSS THE MIDDLE PORTION OF THE BAY AND LOWER TIDAL POTOMAC RIVER. ANOTHER LOW COASTAL LOW WILL DEVELOP ALONG THE MID-ATLANTIC COAST LATER MONDAY THROUGH MONDAY NIGHT. DETAILS REMAIN UNCERTAIN AT THIS TIME...BUT SCA WINDS ARE POSSIBLE. SCA CONDITIONS PSBL ON TUES ON THE CHESAPEAKE BAY...WITH INCRSG CHCS WED THRU THE END OF THE WEEK ON ALL WATERS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BJL NEAR TERM...BJL/HAS SHORT TERM...BJL LONG TERM...BJL/SEARS AVIATION...BJL/SEARS MARINE...BJL/SEARS

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