000 FXUS61 KLWX 020739 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 339 AM EDT THU APR 2 2009 .SYNOPSIS... A WARM FRONT WILL BEGIN TO MOVE NORTH ACROSS THE MID ATLANTIC LATER TODAY AND INTO THE OVERNIGHT HOURS. A STRONG LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE ACROSS THE AREA ON FRIDAY...BRINGING A CHANCE OF THUNDERSTORMS TO THE REGION. HIGH PRESSURE WILL BUILD ACROSS THE AREA FOR THE WEEKEND...WITH BREEZY CONDITIONS EXPECTED ON SATURDAY. UNSETTLED WEATHER RETURNS FOR THE FIRST PART OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WEAK FRONTAL ZONE NOW STALLED FROM DELMARVA TO SWRN VA WITH SPOTTY LIGHT RAIN ACROSS SRN DE AND . AREAS OF FOG...DENSE IN PLACES TO 1/4 MILE OR LESS...HAVE DEVELOPED ACROSS THE SHENANDOAH VALLEY /WITH WEBCAMS ALONG I-81 SHOWING DENSE FOG/ AND VA PIEDMONT WITH FOG ALSO STRADDLING CATOCTIN MOUNTAIN IN MD/FAR ERN WV. RAISED A DENSE FOG ADVISORY FOR SHENANDOAH VALLEY AND VA PIEDMONT THROUGH 14Z...SEE NPWLWX FOR MORE INFORMATION. FURTHER EAST...ALONG I-95 AND EAST ACROSS THE BAY ARE LOW CEILING CLOUDS WITH RESTRICTED VISIBILITIES...THOUGH IN THE ONE TO TWO MILE RANGE AT THIS TIME. THE DENSE FOG ADVISORY WOULD BE EXPANDED SHOULD THE CEILINGS CONTINUE TO LOWER ACROSS THE METRO AREAS. EXPECT LLVL ONSHORE FLOW TO RESTART BY SUNRISE...KEEPING LOW CEILINGS THROUGH THE DAY. EXPECT A GENERAL LIFTING OF CEILING...UP TO 1000 FT INTO THE EARLY AFTERNOON HOURS...THOUGH EXPECT CLOUDS TO REMAIN OPAQUE. THUS...HAVE LIMITED MAX TEMPS TO LOW 60S THE FRONTAL BOUNDARY DRAPED OFF THE MID ATLANTIC RETURNS AS WARM FRONT AHEAD OF THE NEXT SYSTEM /CURRENTLY CROSSING THE OK/TX BORDER/ THIS EVENING INTO TONIGHT WITH RAIN CHANCES INCREASING TO CHC IN THE LATE AFTERNOON ACROSS SW ZONES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... MOISTURE FLUX AHEAD OF THE LOW ENTERING THE OH VALLEY BY LATE EVENING LEADS TO SHOWER ACTIVITY...PARTICULARLY AFTER MIDNIGHT WITH CATEGORICAL POPS FOR SHOWERS GENERALLY WEST OF THE BLUE RIDGE. LOW DIURNAL TEMPERATURE RANGE AGAIN WITH LOWS TONIGHT GENERALLY AROUND 50. WITH LOW CENTER MUCH CLOSER THAN WITH FROPA YESTERDAY...EXPECT GREATER RAINFALL TOTALS. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... FRIDAY STILL LOOKS TO BE AN ACTIVE DAY FOR THE FORECAST AREA AS A FRONT MOVES THROUGH THE MID ATLANTIC. THE WEEKEND LOOKS QUIET...BUT SATURDAY WILL BE BREEZY. UNSETTLED WEATHER IS POSSIBLE FOR THE FIRST OF NEXT WEEK...WITH HIGH PRESSURE SETTLING OVERHEAD FOR MID WEEK. STRONG UPPER LOW WILL MOVE NE ACROSS THE MID ATLANTIC ON FRIDAY...ALONG WITH A SURFACE LOW AND COLD FRONT. THE GFS/NAM HAS THE MID LEVEL SYSTEM NEGATIVELY TILTED AS IT CROSSES EASTERN PORTION OF THE CWFA. WARM FRONT SHOULD BE SLOWLY MOVING NORTH ACROSS THE CWFA EARLY ON FRIDAY. WITH BOUNDARY LAYER WINDS OF 15 TO 20KT THE WARM FRONT SHOULD MAKE SOME NORTHWARD PROGRESS THROUGH THE DAY...AND COULD MAKE IT AS FAR AS THE MASON DIXON LINE. STRONG CONVECTION SHOULD BE MOST LIKELY ALONG AND EAST OF THE INTERSTATE 95 CORRIDOR...ESPECIALLY OVER LOWER SOUTHERN MARYLAND. THUNDERSTORMS WILL BE CAPABLE OF PRODUCING STRONG GUSTY WINDS. LAPSE RATES ALSO LOOK STEEP ENOUGH FOR HAIL. STRONG WINDS ARE EXPECTED BEHIND THE FRONT OVERNIGHT FRIDAY....ESPECIALLY IN THE HIGHEST TERRAIN. WIND ADVISORY CRITERIA COULD BE MET OVERNIGHT FRIDAY INTO EARLY SATURDAY FOR THOSE AREAS. ELSEWHERE...WIND GUSTS AROUND 35 KT ARE POSSIBLE ALONG THE MASON-DIXON LINE...CLOSEST TO THE WIND MAXIMA...WITH SLIGHTLY LESSER WIND GUSTS FOR THE REMAINDER OF THE AREA. WIND SPEEDS SHOULD GRADUALLY DIMINISH DURING THE AFTERNOON ON SATURDAY. HIGH PRESSURE WILL BRIEFLY BUILD IN FOR SATURDAY AND SATURDAY NIGHT. THE HIGH CENTER WILL MOVE OFFSHORE EARLY ON SUNDAY. SUNDAY SHOULD BE THE WARMEST DAY WITH SOUTHERLY FLOW ON THE BACKSIDE OF THE HIGH CENTER. A SECOND FRONT IS EXPECTED LATE SUNDAY INTO MONDAY. THE WEATHER COULD REMAIN UNSETTLED INTO TUESDAY. HIGH PRESSURE IS EXPECTED FOR THE MIDDLE OF NEXT WEEK. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... DENSE FOG WEST OF I-95 CORRIDOR WITH LIFR CIGS ALONG EAST OF I-95 TO PERSIST THROUGH THE MID MORNING. CIGS LIFT TO IFR /AT BEST/ BY MIDDAY WITH ONSHORE FLOW MAINTAINING OPAQUE CLOUDS. ADDITIONAL MOISTURE AHEAD OF THE NEXT SYSTEM BRINGS RAIN CHANCES FROM THE SW THIS AFTERNOON INTO THE EVENING WITH LIKELY RAIN ACROSS THE AREA BY THE EARLY MORNING HOURS. SUB VFR CIGS AND VSBYS ARE EXPECTED FRIDAY AS A LOW PRESSURE SYSTEM AND FRONT MOVE THROUGH THE AREA. THIS SYSTEM WILL BRING WIDESPREAD SHOWERS...AND SOME THUNDERSTORMS. CIGS/VSBYS IMPROVE BY SATURDAY...BUT GUSTY WINDS ARE EXPECTED FOR MOST OF THE DAY. VFR CIGS/VSBYS AND DECREASED WINDS ARE EXPECTED ON SUNDAY. && .MARINE... ELY ONSHORE FLOW BEGINS THIS MORNING...INCREASING TO 10 TO 15 KT TONIGHT...AS A WARM FRONT RETURNS TO THE AREA AHEAD OF THE NEXT LOW PRESSURE SYSTEM THAT WILL REACH THE OHIO VALLEY TONIGHT. HAVE RAISED A SCA FOR FRIDAY. THE GRADIENT WILL TIGHTEN ACROSS THE MID ATLANTIC AS A LOW PRESSURE CENTER AND COLD FRONT MOVE ACROSS THE AREA. STRONG WEST WINDS ARE EXPECTED BEHIND THE FRONT FRIDAY NIGHT INTO SATURDAY...AND COULD EVEN REACH GALE CRITERIA. WINDS SHOULD DIMINISH FOR SUNDAY...BUT ARE EXPECTED TO PICK UP OUT OF THE SOUTH SUNDAY NIGHT AND MONDAY AS A SECOND FRONT AFFECTS THE REGION. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR VAZ025>031- 036>040-050-051. WV...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR WVZ052-053. MARINE...SMALL CRAFT ADVISORY FROM 10 AM TO 8 PM EDT FRIDAY FOR ANZ530>537. && $$ BAJ/LISTEMAA