AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 602 PM EDT MON MAR 28 2011 .SYNOPSIS... HIGH PRESSURE WILL BUILD ACROSS THE AREA THROUGH TUESDAY. AN ACTIVE WEATHER PATTERN IS EXPECTED TUESDAY NIGHT THROUGH LATE IN THE WEEK. SEVERAL DISTURBANCES WILL IMPACT THE AREA DURING THIS TIME. HIGH PRESSURE BUILDS IN FOR THE WEEKEND. && .NEAR TERM /THROUGH TUESDAY/... HIGH PRESSURE IS FORECAST TO BE IN CONTROL TONIGHT AND DURING THE DAY TUESDAY. CLEAR SKIES AND GENERALLY LIGHT WINDS WILL ALLOW FOR DECENT RADIATIONAL COOLING CONDITIONS...WITH TEMPERATURES DROPPING INTO THE 20S AND PERHAPS EVEN TEENS OVER THE HIGHLANDS. TUESDAY WILL FEATURE A COLD START TO THE DAY...BUT TEMPERATURES ARE EXPECTED TO WARM AOA 50F /EXCEPT OVER THE RIDGES AND PERHAPS NORTHEAST MARYLAND/ DURING THE AFTERNOON WITH SUNSHINE MUCH OF THE DAY. HIGH CLOUDS WILL BEGIN TO INCREASE AGAIN LATER IN THE AFTERNOON. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... MODELS HAVE TRENDED A LITTLE SLOWER AND ALSO A LITTLE LESS AGGRESSIVE REGARDING THE NEXT SYSTEM TO AFFECT THE MID ATLANTIC TUESDAY NIGHT INTO WEDNESDAY. MUCH OF TUESDAY NIGHT MAY BE DRY...EXCEPT FOR PERHAPS THE SOUTHWEST PORTION OF THE CWA. BRUNT OF MOISTURE LOOKS TO AFFECT THE AREA ON WEDNESDAY. NAM AND GFS BOTH SHOW A RELATIVELY FLAT WAVE. NAM SUPPRESSES MORE QPF TO THE SOUTH. GFS HAS QPF ACROSS THE CWA BUT TOTALS ARE DOWN FROM PREVIOUS RUNS. FAVOR A BLEND OF THE TWO...BUT MORE A LEAN TOWARD THE GFS. STILL BELIEVE PRECIP WILL MAKE IT NORTH OF THE MASON DIXON LINE SO WILL KEEP LIKELY TO CATEGORICAL POPS. THERE STILL MAY BE A LITTLE BIT OF SNOW AT THE ONSET ACROSS THE CWA...AND SNOW COULD HANG ON ACROSS HIGHER ELEVATIONS WEST OF THE BLUE RIDGE LONGER INTO WEDNESDAY FOR SOME ACCUMULATION BUT LATEST TRENDS SUGGEST MORE RAIN THAN SNOW FOR VALLEYS/LOWER ELEVATIONS. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... ONE AFTER THE OTHER AND LITTLE BREAK IN BETWEEN...THAT IS THE STORY OF THE LONG TERM. AN UPPER RIDGE CENTERED OVER THE PACIFIC COASTLINE AND A DEEP UPPER TROUGH OVER CNTRL/ERN CANADA THRU THE REST OF THE WEEK. POTENT UPPER VORT MAXES WILL GET FEED DOWN IN BETWEEN THESE FEATURES...SWINGING THEM DOWN FROM THE PAC NW THRU THE CNTRL PLAINS AND DOWN TOWARD THE SERN ATLC COAST. THE LOW PRESSURE WAVE THAT IS CURRENTLY MOVING OFF THE SERN ATLC COAST WAS SIMILAR TO THE ONE THAT PASSED OVER THE AREA THIS PAST WEEKEND. THE SYSTEM ON WED WILL BE THE THIRD IN THIS SERIES...THEN DEEPER VORT MAXES WILL BRING THE NEXT COUPLE OF LOW PRESSURE WAVES CLOSER TO THE MID ATLC. AS THE WED STORM SYSTEM MAKES ITS EXIT OFF THE CAROLINA COAST OVERNIGHT INTO THU MRNG. A WEAK BUT LARGE AREA OF HIGH PRESSURE WILL BE STATIONED OVER NEW ENGLAND AND SERN CANADA. WITH THE EXITING LOW JUST TO THE SOUTH...A COLD AIR WEDGE SITUATION WILL UNFOLD ACROSS THE MID ATLC FOR MUCH OF THE DAY THU JUST AHEAD OF THE NEXT SYSTEM. SCATTERED LIGHT RAIN...PATCHY DRIZZLE...OVERCAST SKIES AND ONSHORE FLOW EXPECTED. EARLIER RUNS OF THE GFS DIRECTED ONE OF THESE UPPER VORTS AROUND THE BASE OF A DEEP UPPER TROF /OVER THE GREAT LAKES AND DOWN INTO THE LOWER MS VLY/ AND UP THRU THE MID ATLC OVERNIGHT THU INTO FRI. 12Z GUIDANCE HOWEVER IS NOW DOUBLING THAT AMOUNT TO TWO UPPER WAVES - THE FIRST STILL OVERNIGHT THU/EARLY FRI AND THE OTHER RIGHT ON ITS HEELS AND JUST OFF THE MID ATLC COAST LATER THAT NIGHT. STILL TOO EARLY TELL HOW MUCH QPF...RAIN/SNOW LINES BUT IT APPEARS A LARGE CHUNK OF THE CWA /OUTSIDE OF THE COAST AND THE MTNS/ WILL HAVE A BACK-AND-FORTH MIX OF RAIN AND SNOW. SURFACE TEMPS WILL LIKELY BE A BIT TOO WARM FOR MUCH ACCUMULATION...ESPECIALLY IF RAIN IS INVOLVED FOR ANY EXTENDED PERIOD OF TIME. OVERNIGHT...AS A BULK OF PRECIPITATION MOVES NORTH AND EASTWARD ACROSS THE REGION...A COASTAL LOW WILL BE DEVELOPING JUST OFF DELMARVA WHICH MAY CAUSING SOME BANDING OF PRECIP ALONG THE I-95 CORRIDOR BEFORE THE SYSTEM EXITS. TOO EARLY TO TELL HOW MUCH OF THIS WOULD BE WINTRY PRECIP - MORE LIKELY ON THE WRN EDGE WHERE COLDER AIR WOULD BE WRAPPING TOWARD THE LOW CENTER. THE NEXT VORT MAX IS EVEN MORE UNCERTAIN...AND IS PROGGED TO DEVELOP A STRONGER COASTAL LOW BUT BE FURTHER AWAY FROM LAND AS IT INTENSIFIES LATER THAT NIGHT/OVERNIGHT. THE END OF THE CURRENT NAM CYCLE IS IN AGREEMENT W/ THE GFS AND THE EURO APPEARS TO BE THE CURRENT OUTLIER...DRAGGING THE THU NIGHT STORM SYSTEM WELL OFF THE ATLC COAST BUT THEN BRINGING THE SECOND VORT IN ON SAT. THEN...A SUSPICIOUSLY STRONG LOW PRESSURE SYSTEM APPEARS IN AT THE END OF THE CURRENT FORECAST CYCLE...TRUDGING ACROSS THE NRN PLAINS AND THE GREAT LAKES THIS COMING WEEKEND. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... HIGH PRESSURE WILL PROVIDE VFR CONDITIONS THROUGH TUESDAY. WAVE OF LOW PRESSURE PASSING SOUTH OF THE REGION WILL BRING LOWER CIGS LATE TUESDAY NIGHT INTO WEDNESDAY. HAVE MEDIUM TO HIGH CONFIDENCE IN MVFR RESTRICTIONS...ALTHOUGH CONFIDENCE IS LOWER IN IFR ATTM EXPECT PERHAPS CHO WHICH IS EXPECTED TO FEEL GREATER IMPACT FROM WAVE. CANT RULE OUT A LITTLE SNOW OR RAIN/SNOW AT THE ONSET...BUT FOR THE MOST PART P-TYPE IS EXPECTED TO BE RAIN AT THE HUBS. SEVERAL WX-SYSTEMS IN THE EXTENDED. AS ONE SYSTEM EXITS ON WED EVE...ANOTHER WILL BE MAKING AN ENTRANCE FROM THE SW LATER THAT NIGHT AND INTO THE EARLY MORNING HRS. THE MID ATLC LOOKS TO BE COVERED BY A MARINE LAYER DURING THE DAY ON THU...W/ PERIODS OF -RA/DZ - LOW CLOUDS AND ELY ONSHORE FLOW. LATER THU NIGHT AND INTO EARLY FRI MORNING...THE NEXT LOW PRESSURE AREA WILL MOVE UP THE ATLC COAST W/ A POSSIBLE WINTRY PRECIP MIXTURE WEST OF I-95 - ENDING EARLY FRI. GUIDANCE ALSO POINTING TO ANOTHER FAIRLY SIMILAR SYSTEM MOVING IN ONLY 12-18 HRS LATER BUT POSSIBLY JUST OFF THE COAST HAVING LESSER IMPACTS /IN TERMS OF PRECIP/ ON THE MID ATLC REGION. && .MARINE... NORTHERLY WINDS WILL LIKELY BRING 15 TO 20 KNOT WIND SPEEDS DOWN THE BAY LATE TONIGHT INTO TUESDAY MORNING. WILL CONTINUE SCA. HIGH PRESSURE OVER THE REGION TUESDAY WILL WEAKEN TUESDAY NIGHT AS A WAVE OF LOW PRESSURE IS FORECAST TO MOVE SOUTH OF THE WATERS ON WEDNESDAY. WINDS OVER THE WATERS WILL BE FAIRLY LIGHT FOR MUCH OF THE MED-LONG RANGE OTHER THAN A COUPLE OF COASTAL LOW PASSAGES OFF DELMARVA LATER THIS WEEK. AFTER THE FIRST LEAVES THE CAROLINA COAST LATE WED...ANOTHER LOW PRESSURE SYSTEM WILL DEVELOP ACROSS THE DEEP SOUTH AND MOVE OFF THE MID ATLC COAST BY EARLY FRI. AS THIS FEATURE STRENGTHENS JUST EAST OF DELMARVA...WINDS WILL LIKELY PICK UP OVER THE BAY INTO SCA CONDITIONS UNTIL THE LOW MOVES WELL OF THE COAST ON SAT. && .FIRE WEATHER... LIKE TODAY...TUESDAY WILL FEATURE LOW RH VALUES IN THE 20S DURING THE AFTERNOON...AND FUEL MOISTURES WILL ALSO BE LOW ESPECIALLY ACROSS NORTHEAST MARYLAND. HOWEVER...WINDS ARE EXPECTED TO REMAIN AOB 15 MPH PRECLUDING ANY NEED FOR FIRE HEADLINES. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EDT TUESDAY FOR ANZ530>534-537-539>541-543. && $$ UPDATE...WOODY!