796 FXUS61 KRLX 011956 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 253 PM EST MON MAR 1 2010 .SYNOPSIS... COLD NORTHWEST FLOW CONTINUES THRU TONIGHT. MAINLY DRY WEATHER TUESDAY. UPPER LEVEL SYSTEM BRINGS SNOW SHOWERS TUESDAY NIGHT THROUGH THURSDAY ESPECIALLY MOUNTAINS. WARMER AND DRIER NEXT WEEKEND. && .NEAR TERM /THROUGH TUESDAY/... UPSLOPE SNOW SHOWERS CONTINUE ACROSS THE NORTHERN MOUNTAINS...WITH PATCHY FLURRIES/DRIZZLE CONTINUING ACROSS THE REMAINDER OF THE FORECAST AREA. EXPECT ANY PRECIPITATION WILL TAPER OFF AND END EARLY TONIGHT. HOWEVER...THE DRY WEATHER SHOULD NOT LAST LONG AS MODELS INDICATE AN UPPER LOW WITH SEVERAL MID-LEVEL SHORTWAVES WILL IMPACT THE AREA ON TUESDAY. IN ADDITION...SURFACE LOW WILL MOVE FROM NORTHEAST GULF LATE TONIGHT TO SOUTH CAROLINA COAST BY LATE TUESDAY. IN RESPONSE TO SOUTHEAST LOW...WILL CONTINUE CHANCE POPS IN THE MOUNTAINS ON TUESDAY. MODELS DO NOT SHOW MUCH IN THE WAY OF PRECIPITATION ASSOCIATED WITH THE UPPER LEVEL FEATURES NEAR US. BUT FIND IT HARD TO BELIEVE THAT WE WILL BE DRY WITH THIS FEATURE...AND PLAN TO HANDLE THIS WITH A MENTION OF FLURRIES/SPRINKLES ACROSS THE LOWER ELEVATIONS. GUIDANCE TEMPS FOR TONIGHT ARE CLOSE TO EARLIER FORECASTED NUMBERS AND WILL BE FOLLOWED. MAV SEVERAL DEGREES WARMER THAN MET NUMBERS ON TUESDAY. SEE NO REASON WHY TEMPS ON TUESDAY WOULD BE COLDER THAN READINGS EXPECTED THIS AFTERNOON...SO PLAN ON GOING CLOSER TO THE MAV NUMBERS. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... TRICKY FCST IN THE SHORT TERM. NOT SO MUCH WITH OVERALL SYNOPTIC EVOLUTION REGARDING THE SOUTHERN SYS...BUT MORE IN THE DETAILS REGARDING PCPN AND TYPE ACROSS THE AREA. SFC LOW OFF KILM WILL INTENSIFY OVER GULF STREAM AS SOME PHASING OCCURS WITH NORTHERN STREAM S/W TROF AMID AN INCREASING BAROCLINIC ZONE. MOST OF THE FORCING AND ASSOCIATED PCPN WITH THIS STAYS SE OF THE AREA...PERHAPS BRUSHING SW VA WITH A FEW HRS OF LIGHT SYNOPTIC SNOW LATE TUE NIGHT. ELSEWHERE...WILL HAVE TO DEPEND ON UPSLOPE SETUP FOR ANY MEANINGFUL PCPN. AND HERE IN LIES THE ISSUE. FLOW DOESNT REALLY TURN MORE NW UNTIL WED NIGHT...AND EVEN THEN ITS MORE FROM A NNW DIRECTION. LOOKING AT H85 STREAMLINES OFF THE NAM...LOOKS LIKE LAKE ERIE IS IN PLAY CONCERNING TRAJECTORIES. WITH SOME ICE ON ERIE...PARTICULARLY WESTERN PORTIONS...NOT EXPECTING TOO MUCH OF A MOISTURE CONTRIBUTION TO THE AREA. ABSENT THAT...BUFFR PROFILES OVER THE NORTHERN MTNS SHOW SOME LOW LEVEL INSTABILITY IN THE FORM OF NEGATIVE DELTA THETA E UP TO ABOUT H85 WITH DECENT OMEGA. SO THERE APPEARS TO BE SUFFICIENT LIFT FOR OROGRAPHIC ENHANCED PCPN. THE PROBLEM IS MOISTURE DEPTH. NAM SOUNDINGS SHOW RH GENERALLY HANGING ARND THE -10C AT THE VERY TOP OF CLOUD LAYER ARND H80-H85...WITH THE DENDRITIC GROWTH ZONE MUCH HIGHER. THERE IS ALSO A PRONOUNCED DRY LAYER BETWEEN H8-H6 COURTESY OF SOME MID LEVEL SUBSIDENCE ON BACK SIDE OF THE SFC LOW. ALL OF THIS PRESENTS SOME ICE CRYSTAL CONUNDRUMS...PARTICULARLY OUTSIDE OF THE MTNS. HAVING SAID THAT...NOT TOO CONFIDENT ON DZ AND FRZ DZ SINCE A SLIGHT NORTH AND WEST ADJUSTMENT WITH DEEPER RH ASSOCIATED WITH SFC LOW WOULD MITIGATE ANY OF THOSE CONCERNS. NAM HAS ITS WESTWARD EXTENT ALONG EASTERN SLOPES AS IT STANDS NOW. AS A RESULT DECIDED AGAINST INCLUDING DZ AND FRZ DZ IN WX GRIDS FOR TUE NIGHT INTO WED ATTM. COULD SEE DZ/FRZ DZ INCLUDED IN THE WX GRIDS WITH LATER SHIFTS SHOULD A CLEARER TREND REGRADING HOW FAR NW DEEPER RH SHIELD PRESENT ITSELF. EXPECT MOST LKLY CANDIDATES WOULD BE SE OH INTO WESTERN LOWLANDS. CAA SENDS GROWTH ZONE DOWN INTO THE RH WED NIGHT WHEN UPSLOPE BECOMES MORE OF A FACTOR. WENT WITH FLURRIES FOR THE LOWLANDS TUE NIGHT AND WED WITH SHSN ACROSS THE MTNS. AGAIN...COULD SEE A FEW HRS OF SYNOPTIC LIGHT SNOW ACROSS SW VA INTO SOUTHERN MTNS OVERNIGHT TUE. RAMPED UP POPS WED EVE AND OVERNIGHT WED WITH AFOREMENTIONED UPSLOPE SETUP...WITH CAT POPS ACROSS THE MTNS. AGAIN...WITH RH AND DENDRITIC GROWTH CONCERNS...THIS DOESNT LOOK TO BE THAT IMPRESSIVE AS FAR AS ACCUMULATIONS GO. PRELIMINARY THINKING IS 2-4 INCHES IN THE NORTHERN AND CENTRAL MTNS/UP TO 6 FAVORED NW FACING AREAS/...MAYBE AN INCH IN THE NORTHERN LOWLANDS. MOISTURE DEPTH GRADUALLY SHRINKS DURING THE DAY THU...CONFINING ANY SHSN TO NORTHERN MTNS. AGAIN...WITH ICE CRYSTAL QUESTIONS...THIS COULD END AS DZ ACROSS LOWLANDS AND FRZ DZ IN THE MTNS. A BLEND OF MAV AND MET GUIDANCE FOR TEMPS LOOK GOOD...YIELDING MID 30S FOR HIGHS ACROSS THE LOWLANDS...20S HIGHER ELEVATIONS OF THE MTNS. WITH STEEP LAPSE RATES BOTH DAYS...COULD SEE SOME TEENS FOR HIGHEST ELEVATIONS ABV 4KFT /IE SNOWSHOE/. LOWS LOOK TO BE IN MID TO UPR 20S TUE NIGHT LOWLANDS/ TEENS MTNS/...AND MID 20S WED NIGHT/TEENS MTNS/. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... UPSLOPE ENDS THURSDAY NIGHT WITH HIGH PRESSURE AND AN UPPER LEVEL RIDGE SLOWLY TRAVERSING THE MISSISSIPPI VALLEY. THICKNESSES AND 850HPA TEMPERATURES WILL INCREASE AFTER FRIDAY...ALLOWING FOR A WEEKEND THAT SHOULD BE NORMAL TO SLIGHTLY ABOVE NORMAL IN TERMS OF THE MAX TEMPERATURES. SHOULD SEE SOME SUN AS WELL FOR THE WEEKEND PRIOR TO THE ARRIVAL OF THE NEXT COLD FRONT...MONDAY INTO TUESDAY. WILL BE WATCHING THE MELT...ESPECIALLY ACROSS THE HIGHER ELEVATIONS OF THE NORTHEAST MOUNTAINS WHERE THE SNOWPACK CONTAINS OVER 4 INCHES OF WATER IN PLACES. FOR NOW...THE EXTENDED LOOKS TO BE ON THE DRIER SIDE...WHICH SHOULD KEEP SNOW MELT RATES IN CHECK. THIS WILL BE MONITORED VERY CLOSELY IN UPCOMING FORECASTS. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... 18Z MONDAY THRU 18Z TUESDAY... NORTHWEST TO NORTH FLOW PERSISTS THRU 18Z TUESDAY...WITH GENERAL MVFR CEILINGS...EXCEPT ISOLATED IFR CEILINGS MAINLY HIGHER ELEVATIONS. ANY PRECIPITATION SHOULD BE LIGHT TODAY THRU EARLY TONIGHT...AND TUESDAY...WITH ISOLATED MVFR VSBYS IN THE PRECIPITATION. AFTER 18Z TUESDAY... IFR CONDITIONS EXPECTED WEDNESDAY AND THURSDAY WITH UPSLOPE SNOW SHOWERS IN THE MOUNTAINS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...26/JSH/30 NEAR TERM...JSH SHORT TERM...30 LONG TERM...26 AVIATION...JSH