Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/23/08

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
330 AM PST THU FEB 21 2008 .SYNOPSIS...ISOLATED SHOWERS IN SAN DIEGO COUNTY THIS MORNING...OTHERWISE VARIABLE CLOUDINESS TODAY. A COUPLE MORE UPPER LEVEL LOW PRESSURE SYSTEMS WILL LIKELY BRING SHOWERS LATE TONIGHT THROUGH FRIDAY AND AGAIN LATE SATURDAY THROUGH SUNDAY. CONTINUED COOL WITH LOCAL GUSTY WINDS AT TIMES IN THE MOUNTAINS AND DESERTS. FAIR AND WARMER MONDAY THROUGH WEDNESDAY OF NEXT WEEK UNDER HIGH PRESSURE. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. .SHORT TERM (TODAY-SAT)...THERE WAS A MIX OF SCT TO BKN LOW CLOUDS W OF THE MOUNTAIN AND HIGH CLOUDINESS EARLY THIS MORNING. ACARS SOUNDINGS INDICATED STRONG NW WINDS ALOFT. ONSHORE GRADIENTS WITH ABOUT 5 MB SAN-IPL. WEAK SHORT WAVE RIDGING HAS BROUGHT AN END TO ORGANIZED PRECIP. HOWEVER...CANNOT COMPLETELY RULE OUT THE POSSIBILTY OF ISOLATED LIGHT SHOWERS TODAY FROM RESIDUAL MOISTURE W OF THE MOUNTAINS COMBINED WITH UPSLOPE FLOW AND ISLAND EFFECTS...MAINLY IN SAN DIEGO COUNTY THIS MORNING. VARIABLE HIGH CLOUDINESS WILL CONTINUE TO STREAM OVER THE AREA. MOST OF THE ENERGY FROM THE NEXT SHORT WAVE TROUGH WILL MOVE PAST TO THE N BUT THERE WILL BE ENOUGH MOISTURE AND DYNAMICS AT OUR LATITUDE FOR AN INCREASING CHANCE OF SHOWERS LATE TONIGHT INTO FRI. THE SNOW LEVEL WILL BE AROUND 6000 FT N AND 7000 FT S. PRELIMINARY RAINFALL ESTIMATES ARE ABOUT A QUARTER TO HALF AN INCH W OF THE MOUNTAINS WITH ABOUT HALF TO ONE INCH ON MOUNTAIN SLOPES WITH UP TO A COUPLE TENTHS IN THE HIGH DESERTS AND LESS THAN A TENTH IN THE LOW DESERTS. SHORT WAVE RIDGING SHOULD AGAIN BRING AN END TO PRECIP LATE FRI NIGHT AND SAT MORNING. THE NEXT TROUGH WILL BRING A CHANCE OF SHOWERS AS EARLY AS SAT EVENING. BREEZY CONDITIONS WILL CONTINUE...MAINLY IN THE MOUNTAINS AND DESERTS...WITH STRONGER WINDS LATE FRI. && .LONG TERM (SUN-WED)...MOST OF THE ENERGY FROM THE NEXT TROUGH WILL ALSO MOSTLY MOVE PAST TO THE N SUN BUT ONCE AGAIN THERE SHOULD BE ENOUGH MOISTURE AND DYNAMICS FOR SHOWERS IN OUR AREA AND GUSTY WINDS IN THE MOUNTAINS AND DESERTS. HIGH PRESSURE ALOFT AND OFFSHORE FLOW IS EXPECTED TO BRING FAIR AND WARMER WEATHER MON THROUGH WED. LARGE SURF SHOULD DEVELOP SUN THROUGH TUE. && .AVIATION... 211100Z...MOSTLY CLOUDY TODAY THROUGH FRIDAY. CLOUD BASE 2000 FT MSL WITH TOPS 5000 FT THIS MORNING. SOME BREAKS IN THE LOW CLOUDS AS THEY BECOME STRATOCU WITH BASE 3500 FT WHILE MID TO HIGH CLOUDS INCREASE THIS PM. A COLD FRONT WILL COME IN THIS EVENING AND CAUSE A DEEP LAYER OF CLOUD FROM 2000 FT MSL TO 10K FEET WITH AREAS OF RAIN SPREADING IN FROM THE WEST STARTING AT ABOUT 10 PM AND CONTINUING INTO FRIDAY MORNING. PARTIAL CLEARING FRIDAY AFTERNOON. WINDS AT 10K FEET WILL INCREASE TO 45 KTS TONIGHT. && .SGX WATCHES/WARNINGS/ADVISORIES... SPECIAL WEATHER STATEMENT. SEE LAXSPSSGX && $$ PUBLIC...DA AVIATION...MACKECHNIE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
806 AM CST THU FEB 21 2008 .DISCUSSION... 806 AM CST UPDATE...WEAKLY DEFINED LAKE EFFECT SNOW BAND HAS REDEVELOPED ALONG COOK COUNTY IL SHORE EARLY THIS MORNING...GRADUALLY SHIFTING NORTH ALONG THE SHORELINE IN WEAK LOW LEVEL ANTICYCLONIC FLOW. WITH EASTWARD SHIFT OF LOW LEVEL RIDGE AXIS...AND INCREASING SHEAR THROUGH BOUNDARY LAYER WITH APPROACHING SHORT WAVE/S EXPECT THIS BAND WILL NOT BE LONG LIVED...AND HAVE AMENDED FORECAST TO INCLUDE MENTION OF LIGHT LES ALONG NORTH SHORE THROUGH MID MORNING. HAVE RECEIVED REPORTS OF FLUFFY ACCUMULATIONS AROUND AN INCH WITHIN A FEW BLOCKS OF LAKE ON FAR NORTH SIDE OF CHICAGO...AND NORTH SHORE AREAS MAY SEE SOME MINOR DRY/FLUFFY ACCUMULATION AS THIS BAND CONTINUES TO DRIFT NORTHWEST ALONG SHORE THIS MORNING. RATZER PREVIOUS DISCUSSION... 318 AM CST MAIN FOCUS FOR THIS FORECAST PACKAGE IS ON THE CHANCES FOR SNOW THURSDAY INTO FRIDAY ACROSS THE SOUTHERN PORTION OF THE CWA AND PESKY LAKE EFFECT SNOW SHOWERS STILL HANGING AROUND THE SOUTHERN HALF OF THE LAKE. BROAD RIDGE OF HIGH PRESSURE COVERING MOST OF THE NORTHERN US EAST OF THE ROCKIES WILL CONTINUE TO SLOWLY TRACK EASTWARD TOWARD THE NE ATLANTIC COAST THRU THURSDAY NIGHT. LAKE EFFECT SNOW BAND CONTINUES TO LINGER ACROSS THE SOUTHERN PORTION OF THE LAKE AS WEAK WIND FIELD HAVE ROTATED AROUND TO BEING OUT OF THE SOUTHEAST. THIS LES WILL LIKELY JUST LAST FOR A FEW MORE HOURS INTO THE MORNING AS HAVING A FETCH OUT OF THE SOUTHEAST IS NOT A GREAT ONE TO CONTINUALLY SUPPORT SNOW DEVELOPMENT EVEN THOUGH INVERSION HEIGHTS REMAIN UP AROUND 7KFT. THIS MAY JUST BE ENOUGH OF A NUISANCE SNOW TO MAKE THE MORNING COMMUTE A PROBLEM AGAIN...PARTICULARLY ALONG THE SHORELINE IN COOK AND LAKE COUNTIES IN ILLINOIS WITH A DUSTING TO A FEW TENTHS OF SNOW POSSIBLE BEFORE AND DURING RUSH HOUR. COLDEST CORE OF TEMPERATURES THIS MORNING HAS BEEN ACROSS CENTRAL WISCONSIN IN ASSOCIATION WITH THE CENTER OF HIGH PRESSURE AND CLEAR SKIES. BACK DOWN ACROSS OUR NECK OF THE WOODS...SOME THIN HIGH LEVEL CLOUDS ARE STARTING TO MOVE INTO THE REGION OUT AHEAD OF THE NEXT WEATHER MAKER FOR OUR AREA. CURRENTLY LOOKS AS THOUGH THE NEXT CHANCES FOR SNOW WILL COME IN TWO ROUNDS...THE FIRST BEING LATE THURSDAY AFTERNOON INTO THE EVENING AND THEN AGAIN ON FRIDAY AFTERNOON INTO THE EVENING. ROUND ONE WILL START UP AS THE UPPER LEVEL RIDGE PROPAGATES EASTWARD TODAY AND WARM AIR ADVECTION KICKS UP ON THE BACKSIDE OF IT. FAIRLY DECENT WEST TO EAST TEMPERATURE GRADIENT WILL BE SET UP AT 850MB WHICH WILL BE THE MAIN FOCUS OF ANY SNOW DEVELOPMENT...MAINLY OFF TO THE SOUTH IN CENTRAL ILLINOIS. CURRENT MOSAIC RADAR TRENDS ACROSS MISSOURI SHOW THIS EASTWARD PROPAGATION OF THIS SNOW IN A SOMEWHAT SHOWERY NATURE. AS THE MAIN FOCUS OF THE WAA PROPAGATES OFF TO THE EAST OVERNIGHT...THERE WILL BE A BRIEF LULL IN THE ACTIVITY AND ROUND TWO WILL START UP FRIDAY AS A 500MB CURRENTLY OVER ARIZONA LIFTS NORTHEASTWARD INTO NORTHERN ILLINOIS ON FRIDAY. SNOWFALL/QPF AMOUNTS DO NOT LOOK ALL THAT IMPRESSIVE AT THE MOMENT AS THE BETTER FORCING WILL REMAIN WELL OFF TO THE SOUTH THROUGHOUT THE EVENTS. FOR THE MOMENT JUST HAVE ABOUT AN INCH OR TWO OF TOTAL SNOW ACCUMULATION ACROSS THE SOUTHERN COUNTIES (LIVINGSTON/FORD/IROQUOIS/BENTON). THE SREF SEEMS TO HAVE BEEN THE TREND SETTER WITH THIS SYSTEM AS THE REST OF THE MODELS HAVE BEEN FLIP FLOPPING A BIT OVER THE PAST FEW DAYS ABOUT WHETHER TO JUST HAVE ONE WAVE COME THROUGH OR TWO. THE SREF HAS BEEN SHOWING THE TWO WAVES FAIRLY CONSISTENTLY OVER THE PAST FEW DAYS AND THAT NOW APPEARS TO BE WHERE THE REST OF THE MODELS WANT TO TREND TO...WHICH APPEARS LOGICAL. NOT TOO MANY OTHER ADJUSTMENTS MADE TO THE GOING GRIDS AS TEMPERATURE FORECAST SEEMS TO BE IN GOOD SHAPE. DID BUMP UP LOWS ON TUESDAY MORNING A TAD TO ACCOUNT FOR THE LIKELY WARM AIR ADVECTION TAKING PLACE OUT AHEAD OF THE NEXT LOW. HALBACH && .AVIATION... 1200 UTC TAFS...LAKE EFFECT SNOW SHOWERS RAPIDLY DISSIPATING EARLY THIS MORNING AS ACARS SOUNDINGS SHOW INVERSION HEIGHTS LOWERING QUICKLY EFFECTIVELY SQUASHING THE SNOW SHOWERS. STILL EXPECT TO SEE SCT-BKN MVFR LAKE EFFECT CLOUDINESS FOR A FEW MORE HOURS THIS MORNING BEFORE FETCH GETS SHORTER AND INVERSION HEIGHT SO LOW THAT CLOUDINESS DISSIPATE. NO OTHER AVIATION CONCERNS EXPECTED OVER THE NEXT 24 HOURS WITH ANY PRECIPITATION OF SIGNIFICANCE LIKELY TO STAY SOUTH OF THE TERMINALS WITH JUST GRADUALLY LOWERING VFR CIGS EXPECTED. CIGS COULD EVENTUALLY BUILD DOWN TO MVFR BY LATER TONIGHT. IZZI && .MARINE... 322 AM CST BENIGN WEATHER EXPECTED OVER THE LAKE THROUGH THE NEXT SEVERAL DAYS WITH NO SIGNIFICANT WINDS/WAVES FORECAST THROUGH THE WEEKEND. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
545 AM CST THU FEB 21 2008 .DISCUSSION... 534 AM CST UPDATE...HAVE REMOVED LIGHT SNOW SHOWERS FROM THE FORECAST FOR THIS MORNING FROM LAKE AND COOK COUNTIES AS THE BAND OF SNOW HAS FALLEN APART AND SHOULD NO LONGER POSE A PROBLEM. HALBACH 318 AM CST MAIN FOCUS FOR THIS FORECAST PACKAGE IS ON THE CHANCES FOR SNOW THURSDAY INTO FRIDAY ACROSS THE SOUTHERN PORTION OF THE CWA AND PESKY LAKE EFFECT SNOW SHOWERS STILL HANGING AROUND THE SOUTHERN HALF OF THE LAKE. BROAD RIDGE OF HIGH PRESSURE COVERING MOST OF THE NORTHERN US EAST OF THE ROCKIES WILL CONTINUE TO SLOWLY TRACK EASTWARD TOWARD THE NE ATLANTIC COAST THRU THURSDAY NIGHT. LAKE EFFECT SNOW BAND CONTINUES TO LINGER ACROSS THE SOUTHERN PORTION OF THE LAKE AS WEAK WIND FIELD HAVE ROTATED AROUND TO BEING OUT OF THE SOUTHEAST. THIS LES WILL LIKELY JUST LAST FOR A FEW MORE HOURS INTO THE MORNING AS HAVING A FETCH OUT OF THE SOUTHEAST IS NOT A GREAT ONE TO CONTINUALLY SUPPORT SNOW DEVELOPMENT EVEN THOUGH INVERSION HEIGHTS REMAIN UP AROUND 7KFT. THIS MAY JUST BE ENOUGH OF A NUISANCE SNOW TO MAKE THE MORNING COMMUTE A PROBLEM AGAIN...PARTICULARLY ALONG THE SHORELINE IN COOK AND LAKE COUNTIES IN ILLINOIS WITH A DUSTING TO A FEW TENTHS OF SNOW POSSIBLE BEFORE AND DURING RUSH HOUR. COLDEST CORE OF TEMPERATURES THIS MORNING HAS BEEN ACROSS CENTRAL WISCONSIN IN ASSOCIATION WITH THE CENTER OF HIGH PRESSURE AND CLEAR SKIES. BACK DOWN ACROSS OUR NECK OF THE WOODS...SOME THIN HIGH LEVEL CLOUDS ARE STARTING TO MOVE INTO THE REGION OUT AHEAD OF THE NEXT WEATHER MAKER FOR OUR AREA. CURRENTLY LOOKS AS THOUGH THE NEXT CHANCES FOR SNOW WILL COME IN TWO ROUNDS...THE FIRST BEING LATE THURSDAY AFTERNOON INTO THE EVENING AND THEN AGAIN ON FRIDAY AFTERNOON INTO THE EVENING. ROUND ONE WILL START UP AS THE UPPER LEVEL RIDGE PROPAGATES EASTWARD TODAY AND WARM AIR ADVECTION KICKS UP ON THE BACKSIDE OF IT. FAIRLY DECENT WEST TO EAST TEMPERATURE GRADIENT WILL BE SET UP AT 850MB WHICH WILL BE THE MAIN FOCUS OF ANY SNOW DEVELOPMENT...MAINLY OFF TO THE SOUTH IN CENTRAL ILLINOIS. CURRENT MOSAIC RADAR TRENDS ACROSS MISSOURI SHOW THIS EASTWARD PROPAGATION OF THIS SNOW IN A SOMEWHAT SHOWERY NATURE. AS THE MAIN FOCUS OF THE WAA PROPAGATES OFF TO THE EAST OVERNIGHT...THERE WILL BE A BRIEF LULL IN THE ACTIVITY AND ROUND TWO WILL START UP FRIDAY AS A 500MB CURRENTLY OVER ARIZONA LIFTS NORTHEASTWARD INTO NORTHERN ILLINOIS ON FRIDAY. SNOWFALL/QPF AMOUNTS DO NOT LOOK ALL THAT IMPRESSIVE AT THE MOMENT AS THE BETTER FORCING WILL REMAIN WELL OFF TO THE SOUTH THROUGHOUT THE EVENTS. FOR THE MOMENT JUST HAVE ABOUT AN INCH OR TWO OF TOTAL SNOW ACCUMULATION ACROSS THE SOUTHERN COUNTIES (LIVINGSTON/FORD/IROQUOIS/BENTON). THE SREF SEEMS TO HAVE BEEN THE TREND SETTER WITH THIS SYSTEM AS THE REST OF THE MODELS HAVE BEEN FLIP FLOPPING A BIT OVER THE PAST FEW DAYS ABOUT WHETHER TO JUST HAVE ONE WAVE COME THROUGH OR TWO. THE SREF HAS BEEN SHOWING THE TWO WAVES FAIRLY CONSISTENTLY OVER THE PAST FEW DAYS AND THAT NOW APPEARS TO BE WHERE THE REST OF THE MODELS WANT TO TREND TO...WHICH APPEARS LOGICAL. NOT TOO MANY OTHER ADJUSTMENTS MADE TO THE GOING GRIDS AS TEMPERATURE FORECAST SEEMS TO BE IN GOOD SHAPE. DID BUMP UP LOWS ON TUESDAY MORNING A TAD TO ACCOUNT FOR THE LIKELY WARM AIR ADVECTION TAKING PLACE OUT AHEAD OF THE NEXT LOW. HALBACH && .AVIATION... 1200 UTC TAFS...LAKE EFFECT SNOW SHOWERS RAPIDLY DISSIPATING EARLY THIS MORNING AS ACARS SOUNDINGS SHOW INVERSION HEIGHTS LOWERING QUICKLY EFFECTIVELY SQUASHING THE SNOW SHOWERS. STILL EXPECT TO SEE SCT-BKN MVFR LAKE EFFECT CLOUDINESS FOR A FEW MORE HOURS THIS MORNING BEFORE FETCH GETS SHORTER AND INVERSION HEIGHT SO LOW THAT CLOUDINESS DISSIPATE. NO OTHER AVIATION CONCERNS EXPECTED OVER THE NEXT 24 HOURS WITH ANY PRECIPITATION OF SIGNIFICANCE LIKELY TO STAY SOUTH OF THE TERMINALS WITH JUST GRADUALLY LOWERING VFR CIGS EXPECTED. CIGS COULD EVENTUALLY BUILD DOWN TO MVFR BY LATER TONIGHT. IZZI && .MARINE... 322 AM CST BENIGN WEATHER EXPECTED OVER THE LAKE THROUGH THE NEXT SEVERAL DAYS WITH NO SIGNIFICANT WINDS/WAVES FORECAST THROUGH THE WEEKEND. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1215 PM EST FRI FEB 22 2008 .AVIATION...DISCUSSION FOR 18Z TAFS UPR LOW MVING THRU IL IS FORCING A WINTER MIX OF PRECIP ACRS THE SITES. SHUD SEE FZRA CHANGE OVER TO PL OR A MIX OVR THE NEXT HOUR OR TWO AND THEN CHANGE OVER TO SNOW AT ALL SITES BY 21Z AS THE WARM AIR ALOFT MVS TO THE EAST AND LIFT FROM THE UPR WAVE COOLS THE LAYER. BASED ON UPSTREAM OBS AND TIME HTS CIGS SHUD STAY IFR OR LOWER FOR THE DAY AND EXPECT TRAPPING UNDER INVERSION TO KEEP THEM AROUND OVRNIGHT EXCEPT PERHAPS AT KLAF. VSBYS SHUD STAY MVFR EXCEPT IN AREAS OF PRECIP AND HAVE INCLUDED IFR VSBYS IN TEMPO GROUP FOR AFTERNOON/EVENING PRECIP. && .PREV DISCUSSION... FORECAST FOCUS IS ON PRECIP TYPE AND COVERAGE TODAY. AT 08Z SFC TROF EXTENDED NE FROM LOW NR LA/MS BORDER NE INTO KY. UPPER WAVE EVIDENT ON WV SATELLITE ACROSS SW MO. AREA OF CONVECTION WAS ACROSS NERN AR WITH TSRA ACROSS MS AND AL. MODELS WERE IN FAIR AGREEMENT WITH THE BIG PICTURE. USED A BLEND OVERALL. CURRENT AREA OF CONVECTION ACROSS ERN AR LOOKS TO REMAIN MAINLY SOUTH OF THE FORECAST AREA /FA/ THIS MORNING...BUT MAY SKIRT FAR SRN FA. EXPECT MORE PRECIP TO REDEVELOP LATER THIS MORNIN AS UPPER WAVE AND SFC LOW APPROACH THE OH VALLEY FROM THE SW. ACARS SOUNDINGS SHOW A GOOD INVERSION STILL EXISTS ABOVE IND...SO FZRA STILL A GOOD BET FOR PRECIP TYPE FOR AREAS INDY SOUTH. NRN FA LOOKS TO BE SNOW. AMOUNTS DO NOT LOOK TO BE VERY MUCH THIS MORNING...BUT ANY ICE WILL ADD TO ANY EXISTING PROBLEMS ACROSS SRN FA. THIS AREA MAY SEE THE MOST OF ANY ICING TODAY AS SFC LOW APPROACHES. THUS PLAN TO KEEP SRN TWO TIERS OF COUNTIES IN THE WARNING...BUT THIS WILL BE A BORDERLINE EVENT. WARNING MAY NEED TO BE DOWNGRADED IF PRECIP DOES NOT DEVELOP AS EXPECTED. WILL TRIM NRN TIER OF WARNING BACK TO ADVISORY AS LESS ICING EXPECTED THERE. THIS AFTERNOON MODELS HINTING AT A POSSIBLE TROWAL DEVELOPING ACROSS NRN FA WHICH WILL LEAD TO ADDITIONAL SNOW ACCUMULATION OF A COUPLE OF INCHES. THUS ADVISORY STILL LOOKS GOOD THERE...EVEN THOUGH THERE WON/T BE MUCH PRECIP THIS MORNING. WITH POTENTIAL OF PRECIP THRU THE DAY...DECIDED NOT TO GET FANCY WITH ADVISORY/WARNING TIMES AND LET THEM GO TIL 00Z. THE TIMING CAN BE ADJUSTED AS NEEDED LATER. WENT WITH COOLER MAV TEMPS FOR HIGHS TODAY GIVEN SFC LOW TRACKING TO THE S AND A NRN FLOW CONTINUING AT THE SFC. FORCING WILL DIMINISH TONIGHT AS UPPER TROF EXITS THE AREA. COLDER AIR WILL WORK IN ALOFT SO PRECIP SHOULD BE SNOW. THUS WENT WITH CHANCE POPS. AGAIN WENT COOLER MAV NUMBERS GIVEN POSSIBLE SNOW COVER. WEAK UPPER SYSTEM WILL SKIRT THE AREA TO THE S ON SUNDAY...KEEPING THE PRECIP OUT OF THE AREA. THUS THE WEEKEND LOOKS DRY. STRONGER SYSTEM MOVES IN EARLY NEXT WEEK AND WILL BRING ANOTHER ROUND OF PRECIP TO THE AREA. CURRENT TRENDS WOULD INDICATE THAT TO BE A MAINLY RAIN EVENT. && .IND WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR ALL OF CENTRAL INDIANA. && $$ PUBLIC...CS AVIATION...CP
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
901 PM EST FRI FEB 22 2008 .SYNOPSIS... A COASTAL LOW WILL MOVE NORTH...UP THE MID-ATLANTIC COAST OVERNIGHT. AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION TOMORROW. HIGH PRESSURE WILL BUILD IN BEHIND THIS SYSTEM FOR SUNDAY INTO EARLY NEXT WEEK. THE NEXT STORM SYSTEM WILL AFFECT THE REGION TUESDAY WITH RAIN BEING THE PRIMARY THREAT. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... WATER VAPOR LOOP SHOWS PHASING OCCURRING OVER THE CENTRAL MISSISSIPPI RIVER VALLEY...AS THE NEXT SHORT WAVE DROPS SOUTHEAST TOWARD THE UPPER MIDWEST. ACARS 400-250MB WIND OBSERVATIONS SHOW A SOUTHWESTERLY 125-150KT JET FROM THE WESTERN GULF STATES NORTHEAST OVER THE MID ATLANTIC. 19Z SURFACE ANALYSIS PLACED A 1008MB PARENT CYCLONE IN THE TENNESSEE VALLEY...WITH A WARM/STATIONARY FRONT SOUTHEAST ACROSS GEORGIA...THEN ALONG THE CAROLINA COAST TO A 1008MB CYCLONE NEAR THE MOUTH OF THE CHESAPEAKE BAY. A 1019MB ANTICYCLONE DOMINATES THE MISSISSIPPI RIVER VALLEY. IR SATELLITE SHOWS COLDER CLOUD TOPS HAVE MOVED OUT OF THE REGION...CONFIRMING FORECAST SOUNDINGS AND 00Z KIAD RAOB WITH MOISTURE UP TO 10KFT. THE FORECAST SOUNDINGS SHOW MOISTURE BECOMES CONFINED TO 6KFT OVERNIGHT...INDICATING A DRIZZLE SOUNDING AS TEMPERATURES WITHIN SATURATED LAYER WILL NOT SUPPORT ICE CRYSTALS. WITH DEEP LAYER FLOW REMAINING SOUTHWESTERLY OVERNIGHT AHEAD OF THE MID LEVEL SHORT WAVE...WILL RETAIN MENTION OF DRIZZLE ACROSS NORTHERN FORECAST AREA. THIS NECESSITATES AN EXTENSION OF THE ADVISORY FOR AREAS OF FREEZING DRIZZLE. WITH LIGHT FLOW AND SATURATED LOWER LEVELS...AM CONCERNED CEILINGS WILL BUILD TOWARD THE GROUND AND ALLOW FOG TO BECOME MORE DENSE OVERNIGHT. CONFIDENCE IN PLACING DENSE FOG GEOGRAPHICALLY OR TEMPORALLY IS NOT HIGH AS PERIODIC DRIZZLE WILL TEND TO MIX UP THE ATMOSPHERE AND ALLOW VISIBILITIES TO FLUCTUATE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... REMOVED POPS AS MOISTURE REMAINS SHALLOW DURING THE DAY TOMORROW. AS WITH TONIGHT...SOUNDINGS SUPPORT FREEZING DRIZZLE OR DRIZZLE. CONDITIONS IMPROVE DURING THE AFTERNOON WITH THE MID LEVEL TROUGH/SURFACE FRONTAL PASSAGE FROM THE NORTHWEST. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... SATURDAY NIGHT THROUGH MONDAY: HIGH PRESSURE WILL BUILD ACROSS THE MID-ATLANTIC SATURDAY NIGHT BRINGING SEASONABLE TEMPERATURES ALONG WITH DRIER CONDITIONS. ANY LEFTOVER SNOW SHOWERS WILL BE ISOLATED AND CONFINED MAINLY TO LOCATIONS WEST OF THE BLUE RIDGE SATURDAY EVENING. HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS INTO EARLY NEXT WEEK. A WEAK UPPER-LEVEL DISTURBANCE WILL PASS BY TO OUR SOUTH SUNDAY PERHAPS BRINGING SOME MORE CLOUDS ACROSS PORTIONS OF CENTRAL VIRGINIA. FOR NOW CURRENT THINKING IS THAT PRECIPITATION WITH THIS SYSTEM WILL REMAIN TO THE SOUTH. MONDAY NIGHT THROUGH FRIDAY: THE NEXT SYSTEM WILL MOVE OUT OF THE ROCKIES MONDAY NIGHT INTO TUESDAY AND IT IS EXPECTED TO PHASE WITH THE NORTHERN BRANCH...DRAGGING THE SYSTEM TO OUR WEST ACROSS THE GREAT LAKES BY TUESDAY NIGHT. THIS SHOULD DRAW IN ENOUGH WARM AIR FOR THE PRIMARY PTYPE TO BE RAIN. PERHAPS THERE IS A BIT OF A WINTRY MIX IN THE CLIMO FAVORED LOCATIONS LATER MONDAY NIGHT IF PRECIPITATION STARTS EARLY ENOUGH. THE COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL PASS THROUGH THE REGION TUESDAY EVENING. AN UPPER-LEVEL DISTURBANCE WILL MOVE THROUGH THE REGION BEHIND THIS FRONT OVERNIGHT TUESDAY AND WEDNESDAY BRINGING THE CHANCE FOR RAIN/SNOW SHOWERS...MAINLY ACROSS THE POTOMAC HIGHLANDS. HIGH PRESSURE WILL BRING DRY AND SEASONABLE CONDITIONS FOR THE LATTER PART OF NEXT WEEK. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... IFR CEILINGS/VISIBILITIES AND AREAS OF FREEZING DRIZZLE WILL CONTINUE OVERNIGHT WITH LIGHT FLOW AND SATURATED LOWER LEVELS. AM CONCERNED CEILINGS WILL BUILD TOWARD THE GROUND AND ALLOW FOG TO BECOME MORE DENSE OVERNIGHT. DRIER AIR BUILDS INTO THE REGION LATE DURING TOMORROW AFTERNOON WITH A COLD FRONTAL PASSAGE. HIGH PRESSURE WILL BRING VFR CONDITIONS FOR SATURDAY NIGHT THROUGH MONDAY. THE NEXT STORM SYSTEM WILL BRING A CHANCE FOR IFR/SUB IFR CIGS AND VSBYS BY TUESDAY. DRIER AIR WILL BRING A RETURN OF VFR CONDITIONS FOR THE MIDDLE AND LATTER PART OF NEXT WEEK. && .MARINE... LIGHT FLOW CONTINUES INTO SATURDAY. VISIBILITIES WILL BE RESTRICTED IN FOG OVERNIGHT. WINDS MAY PICK UP A BIT SATURDAY NIGHT BEHIND AN UPPER-LEVEL DISTURBANCE BUT IT SHOULD REMAIN BELOW SCA CRITERIA. TRANQUIL CONDITIONS ARE EXPECTED FOR SUNDAY AND MONDAY. THE NEXT STORM SYSTEM WILL BRING A BETTER CHANCE FOR SCA WINDS FOR TUESDAY AND WEDNESDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER WEATHER ADVISORY UNTIL 9 AM EST SATURDAY FOR DCZ001. MD...WINTER WEATHER ADVISORY UNTIL 9 AM EST SATURDAY FOR MDZ003>007- 009>011-013-014-501-502. VA...WINTER WEATHER ADVISORY UNTIL 9 AM EST SATURDAY FOR VAZ028-031- 041-042-052>054. WV...WINTER WEATHER ADVISORY UNTIL 9 AM EST SATURDAY FOR WVZ050>053- 503-504. MARINE...NONE. && $$ SYNOPSIS...RW/ROGOWSKI NEAR TERM...ROGOWSKI SHORT TERM...ROGOWSKI LONG TERM...BJL AVIATION...ROGOWSKI/BJL MARINE...ROGOWSKI/BJL
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
551 AM CST THU FEB 21 2008 .UPDATE... A MESSY FORECAST...WHICH IS FURTHER COMPLICATED BY WAVERING MODEL QPFS. THE EVENING UA DATA SHOWED LOW LEVEL MOISTURE RETURN IS WELL UNDERWAY ACROSS THE SOUTHERN PLAINS AND THE LATEST REGIONAL RADAR LOOP SHOWS PCPN ALREADY TRYING TO BREAK OUT ACROSS KS IN A REGION OF GOOD ISENTROPIC LIFT. LIFT IS FORECAST TO INCREASE AND SPREAD EASTWARD OVERNIGHT WITH PCPN CONCURRENTLY DEVELOPING AND MOVING INTO SWRN PTNS OF THE CWA BEFORE DAYBREAK. THE IMPORTANT NEW DETAIL TO THIS FCST IS TO DOWNPLAY SNOW AND HIT SLEET AND NOW FREEZING RAIN A BIT HARDER. THE 00Z SGF SOUNDING SHOWED A PRONOUNCED ELEVATED WARM LAYER CENTERED AROUND 800-825 MB AND AN ACARS SOUNDING OUT OF LAMBERT JUST BEFORE 01Z HAD AN ELEVATED WARM NOSE OF AROUND -1 DEGC AT 775 MB. THESE OBSERVATIONS ALONG WITH THE NEWEST NAM GUIDANCE SUGGEST THAT THE ELEVATED WARM WEDGE WILL MOVE RAPIDLY NEWD ON THURSDAY/THURSDAY NIGHT AND DEEPEN WITH TIME. ACROSS THE OZARKS THERE MAY BE A MIX OF FREEZING RAIN AND SLEET IN THE MORNING BUT IT SHOULD RAPIDLY TRANSITION TO ALL FREEZING RAIN WITH SIGNIFICANT ICE ACCUMULATIONS EXPECTED. FURTHER NORTH THERE MAY BE SOME SNOW AT THE ONSET ALONG AND SOUTH OF INTERSTATE 70...BUT THE WARM WEDGE WILL RAPIDLY WIN OUT AND THE PREDOMINATE PCPN TYPE SHOULD BE SLEET AND MAY CHANGE TO FREEZING RAIN AS EARLY AS 00Z FRI. I HAVE TRENDED PCPN TYPES IN THE ABOVE DIRECTION. IF THE 00Z NAM QPF IS CORRECT FOR THURS NIGHT INTO FRIDAY MORNING THEN SLEET...SNOW...AND ICE AMOUNTS WILL NEED TO BE BOOSTED QUITE A BIT FROM I-70 NORTHWARD. ITS SOLUTION IS COMING IN LINE WITH THE ECMWF WITH A BAND OF DEFORMATION ZONE PCPN IMPACTING THIS AREA THURS NIGHT INTO FRI MORNING. HEADLINES WILL THEN BE NEEDED FUTHER NORTH AS WELL. I WILL LET THE MID SHIFT ABSORB THE GFS AND COLLABORATE FURTHER TO HANDLE THIS SCENARIO. AT THIS POINT I UPGRADED THE WATCH TO A WARNING BASED ON SLEET ACCUMULATION AND ICE ACCUMULATION. LASTLY I HAVEN`T EVEN FACTORED IN THE POTENTIAL FOR EMBEDDED ELEVATED THUNDERSTORMS WHICH ARE QUITE POSSIBLE ACROSS SRN MO ON THURSDAY AND EVEN FUTHER NORTH THURS NIGHT INTO EARLY FRI ASSOCIATED WITH STEEP MID LEVEL LAPSE RATES AND LOW LEVEL WAA. GLASS && .DISCUSSION... RATHER COMPLEX FCST FOR THE NEXT FEW DAYS. STORM SYSTEM OVR WRN US CONTINUES TO DIG AND PROPAGATE EWD. THE FIRST S/W WL BEGIN TO IMPACT THE SWRN CWA LATE TNGT WITH AN INITIAL P TYPE OF PL AND SN. THE AREA OF PRCIP WL EVENTUALLY OVERSPREAD MUCH OF THE CWA THURSDAY IN THE LATE MRNG AND EARLY AFTN HOURS. MDLS ARE COMING INTO AGREEMENT WITH REGARD TO MASS FIELDS AND TEMP PROFILES. MDLS HAVE TRENDED WARM AIR ALOFT FURTHER NWD WITH LATEST MDL RUNS. HAVE TRENDED AREAS OF PL FURTHER NWD TO ACCOUNT FOR THIS. MDLS STILL DIFFER REGARDING AMOUNTS AND LOCATION OF PRECIP. THE GFS AND ECMWF KEEP THE BULK OF THE PRECIP FURTHER S WHILE THE NAM AND LOCALLY RUN ARW WRF SPLIT THE PRECIP FIELD WITH A SWATH OF SN ACROSS MUCH OF THE NRN CWA AND A SWATH OF PL...SN AND FZRA ACROSS CENTRAL AND SRN PORTIONS OF THE CWA. AMOUNTS OF FZRA ACROSS PORTIONS OF SERN MO ARE EXPECTED TO BE AOA ONE QUARTER INCH AND HAVE THEREFORE UPGRADED TO A WSW. DUE TO SOME UNCERTAINTIES WITH REGARD TO QPF AMOUNTS AND HOW FAR NWD THE 0/C ISOTHERM AT 850MB WL MV...HAVE CONTINUED THE WWY FROM TMW MRNG THRU FRI. ATTM...EXPECT UPTO 4 INCHES OF PL AND SN FOR AREAS ALONG AND S OF I70. HAVE CONTINUED TO TREND FCST TEMPS DWNWD BLW GUIDANCE FOR THURS AND FRI. TEMPS ON FRI WL DEPEND ON AMOUNT OF FROZEN PRECIP ON THE GROUND AS WELL AS HOW FAST THE SFC RIDGE BUILDS INTO THE AREA. HAVE TRENDED DWNWD BUT DID NOT WANT TO GO TOO COLD DUE TO UNCERTAINTIES WITH REGARD TO MDL TIMING. AS THE SYSTEM EXITS THE CWA ON FRI...CLR SKIES AND NLY WINDS WL REMAIN BEHIND AS THE SFC RIDGE BUILDS INTO THE AREA. ATTM...FRI NGT AND SAT REMAIN DRY. TILLY FOR THE EXTD...THE ACTIVE WX PATTERN CONTS OVR THE AREA WITH TWO S/W TROFS PASSING THRU THE REGION DURING THIS PD. THE FIRST UPR LVL S/W MIGRATES THRU THE MID MS VALLEY REGION SUN MRNG. THE ECMWF SHOWS MORE AMPLITUDE WITH THE WAVE COMPARED TO THE GFS SOLN. THIS IS ALSO NOTED WITH SFC PATTERN WHERE A MORE DEFINED INVERTED TROF IS PLACED FROM W CNTRL THRU S CNTRL MO. MUCH OF THE PRECIP WL FALL IN THE FORM OF LGT SN MAINLY DURING THE MRNG AND EARLY AFTN HOURS AND ALSO MAINLY OVR THE SRN HALF OF THE CWA. THIS WAVE WL EXIT THIS REGION IN THE FAST MVNG WLY FLOW. A STRONGER S/W TROF WL MV THRU THE MID MS VALLEY MON AFTN THRU TUES NGT. THIS SYSTEM APPEARS TO PULL WARMER AIR FROM TH ESW FOLLOWED BY ANOTHER SHOT OF COLD AIR LATE TUES MRNG THRU WED OVR THE REGION. RA/SN MIX IS EXPECTED OVR THE NRN TWO THIRDS OF THE CWA WHILE MAINLY RA CAN BE EXPECTED OVR THE SRN THIRD OF THE CWA. THE PRECIP WL CHANGE OVR TO SHSN ON WED MAINLY OVR E CNTRL MO THRU SW IL. DRY WX IS EXPECTED ON THURS OVR THE ENTIRE CWA. RP && .AVIATION... FOR THE 12Z TAFS... EXPECT DETERIORATING CONDITIONS ACROSS THE REGION TODAY. BAND OF FZRA/PL WITH SOME SN IS MOVING ACROSS CNTRL AND ERN MO AT THIS TIME WITH ADDITIONAL DEVELOPMENT OVER SWRN MO/NERN OK/SERN KS. HAVE TEMPO GROUPS INITIALLY AT KSTL/KSUS/KCOU AND THEN GO PREDOMINATE THROUGH THE MORNING WITH LOWERING MVFR CIGS AS THIS INITIAL BATCH OF PRECIPITATION MOVES THROUGH. THINK PRECIPITATION WILL DECREASE SOMEWHAT LATER THIS AFTERNOON INTO THE EVENING AND THEN PICK BACK UP OVERNIGHT. EXPECT CEILINGS TO ALSO FALL TO IFR BY 19-22Z. AT KUIN...PRECIPITATION TYPE WILL BE SNPL. EXPECT PERSISTENT E-NELY WINDS THROUGH THE PERIOD. BRITT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING UNTIL 6 PM CST FRIDAY FOR CRAWFORD-IRON- MADISON-REYNOLDS-ST. FRANCOIS-WASHINGTON. WINTER STORM WARNING UNTIL 6 PM CST FRIDAY FOR AUDRAIN-BOONE- CALLAWAY-COLE-FRANKLIN-GASCONADE-JEFFERSON-LINCOLN-MONITEAU- MONTGOMERY-OSAGE-PIKE-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY- STE. GENEVIEVE-WARREN. WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 PM CST FRIDAY FOR KNOX-LEWIS-MARION-MONROE-RALLS-SHELBY. IL...WINTER STORM WARNING UNTIL 6 PM CST FRIDAY FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-JERSEY IL-MACOUPIN IL- MADISON IL-MARION IL-MONROE IL-MONTGOMERY IL-RANDOLPH IL- ST. CLAIR IL-WASHINGTON IL. WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 PM CST FRIDAY FOR ADAMS IL-BROWN IL-PIKE IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
1155 PM CST WED FEB 20 2008 .UPDATE... A MESSY FORECAST...WHICH IS FURTHER COMPLICATED BY WAVERING MODEL QPFS. THE EVENING UA DATA SHOWED LOW LEVEL MOISTURE RETURN IS WELL UNDERWAY ACROSS THE SOUTHERN PLAINS AND THE LATEST REGIONAL RADAR LOOP SHOWS PCPN ALREADY TRYING TO BREAK OUT ACROSS KS IN A REGION OF GOOD ISENTROPIC LIFT. LIFT IS FORECAST TO INCREASE AND SPREAD EASTWARD OVERNIGHT WITH PCPN CONCURRENTLY DEVELOPING AND MOVING INTO SWRN PTNS OF THE CWA BEFORE DAYBREAK. THE IMPORTANT NEW DETAIL TO THIS FCST IS TO DOWNPLAY SNOW AND HIT SLEET AND NOW FREEZING RAIN A BIT HARDER. THE 00Z SGF SOUNDING SHOWED A PRONOUNCED ELEVATED WARM LAYER CENTERED AROUND 800-825 MB AND AN ACARS SOUNDING OUT OF LAMBERT JUST BEFORE 01Z HAD AN ELEVATED WARM NOSE OF AROUND -1 DEGC AT 775 MB. THESE OBSERVATIONS ALONG WITH THE NEWEST NAM GUIDANCE SUGGEST THAT THE ELEVATED WARM WEDGE WILL MOVE RAPIDLY NEWD ON THURSDAY/THURSDAY NIGHT AND DEEPEN WITH TIME. ACROSS THE OZARKS THERE MAY BE A MIX OF FREEZING RAIN AND SLEET IN THE MORNING BUT IT SHOULD RAPIDLY TRANSITION TO ALL FREEZING RAIN WITH SIGNIFICANT ICE ACCUMULATIONS EXPECTED. FURTHER NORTH THERE MAY BE SOME SNOW AT THE ONSET ALONG AND SOUTH OF INTERSTATE 70...BUT THE WARM WEDGE WILL RAPIDLY WIN OUT AND THE PREDOMINATE PCPN TYPE SHOULD BE SLEET AND MAY CHANGE TO FREEZING RAIN AS EARLY AS 00Z FRI. I HAVE TRENDED PCPN TYPES IN THE ABOVE DIRECTION. IF THE 00Z NAM QPF IS CORRECT FOR THURS NIGHT INTO FRIDAY MORNING THEN SLEET...SNOW...AND ICE AMOUNTS WILL NEED TO BE BOOSTED QUITE A BIT FROM I-70 NORTHWARD. ITS SOLUTION IS COMING IN LINE WITH THE ECMWF WITH A BAND OF DEFORMATION ZONE PCPN IMPACTING THIS AREA THURS NIGHT INTO FRI MORNING. HEADLINES WILL THEN BE NEEDED FUTHER NORTH AS WELL. I WILL LET THE MID SHIFT ABSORB THE GFS AND COLLABORATE FURTHER TO HANDLE THIS SCENARIO. AT THIS POINT I UPGRADED THE WATCH TO A WARNING BASED ON SLEET ACCUMULATION AND ICE ACCUMULATION. LASTLY I HAVEN`T EVEN FACTORED IN THE POTENTIAL FOR EMBEDDED ELEVATED THUNDERSTORMS WHICH ARE QUITE POSSIBLE ACROSS SRN MO ON THURSDAY AND EVEN FUTHER NORTH THURS NIGHT INTO EARLY FRI ASSOCIATED WITH STEEP MID LEVEL LAPSE RATES AND LOW LEVEL WAA. GLASS && .DISCUSSION... RATHER COMPLEX FCST FOR THE NEXT FEW DAYS. STORM SYSTEM OVR WRN US CONTINUES TO DIG AND PROPAGATE EWD. THE FIRST S/W WL BEGIN TO IMPACT THE SWRN CWA LATE TNGT WITH AN INITIAL P TYPE OF PL AND SN. THE AREA OF PRCIP WL EVENTUALLY OVERSPREAD MUCH OF THE CWA THURSDAY IN THE LATE MRNG AND EARLY AFTN HOURS. MDLS ARE COMING INTO AGREEMENT WITH REGARD TO MASS FIELDS AND TEMP PROFILES. MDLS HAVE TRENDED WARM AIR ALOFT FURTHER NWD WITH LATEST MDL RUNS. HAVE TRENDED AREAS OF PL FURTHER NWD TO ACCOUNT FOR THIS. MDLS STILL DIFFER REGARDING AMOUNTS AND LOCATION OF PRECIP. THE GFS AND ECMWF KEEP THE BULK OF THE PRECIP FURTHER S WHILE THE NAM AND LOCALLY RUN ARW WRF SPLIT THE PRECIP FIELD WITH A SWATH OF SN ACROSS MUCH OF THE NRN CWA AND A SWATH OF PL...SN AND FZRA ACROSS CENTRAL AND SRN PORTIONS OF THE CWA. AMOUNTS OF FZRA ACROSS PORTIONS OF SERN MO ARE EXPECTED TO BE AOA ONE QUARTER INCH AND HAVE THEREFORE UPGRADED TO A WSW. DUE TO SOME UNCERTAINTIES WITH REGARD TO QPF AMOUNTS AND HOW FAR NWD THE 0/C ISOTHERM AT 850MB WL MV...HAVE CONTINUED THE WWY FROM TMW MRNG THRU FRI. ATTM...EXPECT UPTO 4 INCHES OF PL AND SN FOR AREAS ALONG AND S OF I70. HAVE CONTINUED TO TREND FCST TEMPS DWNWD BLW GUIDANCE FOR THURS AND FRI. TEMPS ON FRI WL DEPEND ON AMOUNT OF FROZEN PRECIP ON THE GROUND AS WELL AS HOW FAST THE SFC RIDGE BUILDS INTO THE AREA. HAVE TRENDED DWNWD BUT DID NOT WANT TO GO TOO COLD DUE TO UNCERTAINTIES WITH REGARD TO MDL TIMING. AS THE SYSTEM EXITS THE CWA ON FRI...CLR SKIES AND NLY WINDS WL REMAIN BEHIND AS THE SFC RIDGE BUILDS INTO THE AREA. ATTM...FRI NGT AND SAT REMAIN DRY. TILLY FOR THE EXTD...THE ACTIVE WX PATTERN CONTS OVR THE AREA WITH TWO S/W TROFS PASSING THRU THE REGION DURING THIS PD. THE FIRST UPR LVL S/W MIGRATES THRU THE MID MS VALLEY REGION SUN MRNG. THE ECMWF SHOWS MORE AMPLITUDE WITH THE WAVE COMPARED TO THE GFS SOLN. THIS IS ALSO NOTED WITH SFC PATTERN WHERE A MORE DEFINED INVERTED TROF IS PLACED FROM W CNTRL THRU S CNTRL MO. MUCH OF THE PRECIP WL FALL IN THE FORM OF LGT SN MAINLY DURING THE MRNG AND EARLY AFTN HOURS AND ALSO MAINLY OVR THE SRN HALF OF THE CWA. THIS WAVE WL EXIT THIS REGION IN THE FAST MVNG WLY FLOW. A STRONGER S/W TROF WL MV THRU THE MID MS VALLEY MON AFTN THRU TUES NGT. THIS SYSTEM APPEARS TO PULL WARMER AIR FROM TH ESW FOLLOWED BY ANOTHER SHOT OF COLD AIR LATE TUES MRNG THRU WED OVR THE REGION. RA/SN MIX IS EXPECTED OVR THE NRN TWO THIRDS OF THE CWA WHILE MAINLY RA CAN BE EXPECTED OVR THE SRN THIRD OF THE CWA. THE PRECIP WL CHANGE OVR TO SHSN ON WED MAINLY OVR E CNTRL MO THRU SW IL. DRY WX IS EXPECTED ON THURS OVR THE ENTIRE CWA. RP && .AVIATION... FOR THE 06Z TAFS... WINTER STORM IS DEVELOPING OVER THE PLAINS...AND MARGINAL CIGS ARE MOVING UP INTO SOUTHWEST MISSOURI AT THIS TIME. ALSO SEEING SOME LIGHT PRECIPITATION DEVELOPING OVER SOUTHWEST MISSOURI ON RADAR. VFR CIGS WILL OVERSPREAD THE AREA...THEN LOWER AND THICKEN THROUGH 12Z. I EXPECT PRECIPITATION AND MVFR CIGS TO AFFECT SOUTHEAST MISSOURI FIRST...PROBABLY BEFORE 12Z...WITH THE LOWER CIGS AND PRECIP TO RAPIDLY OVERSPREAD THE REST OF THE AREA AFTER 12Z. TRYING TO TIME IN CIGS BELOW 2000FT IS DIFFICULT AT THIS STAGE...BUT IT SEEMS LIKELY THAT MUCH OF THE AREA WILL BE BELOW 2000FT BY 15 OR 16Z...WITH IFR TO FOLLOW AFTER 18Z. PRECIP WILL LIKELY START WITH A LITTLE SNOW...BUT CHANGE RAPIDLY OVER TO SLEET ALONG THE I-70 CORRIDOR WITH FREEZING RAIN OVER SOUTHEAST MISSOURI. SNOW MAY LINGER LONGER OVER NORTHEAST MISSOURI/WEST CENTRAL ILLINOIS. CARNEY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WARNING FROM 3 AM THURSDAY TO 6 PM CST FRIDAY FOR CRAWFORD-IRON-MADISON-REYNOLDS-ST. FRANCOIS-WASHINGTON. WINTER STORM WARNING FROM 6 AM THURSDAY TO 6 PM CST FRIDAY FOR AUDRAIN-BOONE-CALLAWAY-COLE-FRANKLIN-GASCONADE-JEFFERSON- LINCOLN-MONITEAU-MONTGOMERY-OSAGE-PIKE-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN. IL...WINTER STORM WARNING FROM 6 AM THURSDAY TO 6 PM CST FRIDAY FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL-JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL-MONTGOMERY IL- RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1255 PM EST FRI FEB 22 2008 .SYNOPSIS... A COLD MOIST AIRMASS WILL LINGER OVER THE AREA TODAY... AS A LOW PRESSURE SYSTEM PASSES TO THE SOUTH OF THE REGION AND OFF THE COAST TONIGHT. ANOTHER WEAK LOW PRESSURE SYSTEM WILL DRIFT ACROSS THE AREA EARLY SATURDAY... THEN A COLD FRONT WILL MOVE SOUTHEAST ACROSS THE AREA SATURDAY EVENING. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1145 AM FRIDAY... THE COLD AIR DAMMING REGIME REMAINS FIRMLY ENTRENCHED ACROSS CENTRAL NC. LATEST AMDAR SOUNDINGS FROM AIRCRAFT AND 12Z REGIONAL ANALYSES AT 925 MB AND 850 MB INDICATE A RELATIVELY DEEP SURFACE-BASED STABLE LAYER CAPPED BY VERY WARM AIR ALOFT... ON THE ORDER OF +8 TO +10C. DESPITE THE PERSISTENCE OF NEAR-FREEZING SURFACE TEMPS ACROSS THE NORTHWEST PIEDMONT... HYDROMETEORS DROPPING THROUGH THIS WARMTH ALOFT ARE UNLIKELY TO GET COLD ENOUGH TO FREEZE. CALLS TO COUNTY OFFICIALS IN THIS AREA REVEAL NO PROBLEMS WITH ICING. THUS... THE ADVISORY HAS BEEN ALLOWED TO EXPIRE. PRECIPITATION COVERAGE HAS DECREASED CONSIDERABLY LATE THIS MORNING IN THE WAKE OF THE MID LEVEL WAVE NOW SHIFTING INTO EASTERN NC. WITH AN OVERALL LACK OF ATLANTIC INFLOW ABOVE THE STABLE POOL... AND THE PRESENCE OF A LINE OF CONVECTION FROM SRN GA THROUGH THE FL PANHANDLE LIMITING THE GULF-SOURCE MOISTURE TRANSPORT INTO NC... HAVE TRIMMED BACK ON POPS FOR THE REST OF THE DAY ESPECIALLY IN THE NW. EXPECT LESS THAN AN ADDITIONAL TENTH OR SO OF RAIN IN THE SE CWA WITH JUST A FEW HUNDREDTHS IN THE NW. WITH NO E OR SE WIND COMPONENT IN THE LOWEST FEW THOUSAND FEET TO HELP PUSH THE WEDGE BOUNDARY INLAND... AND MORE IMPORTANTLY WITH THE MOVEMENT OF A SURFACE LOW UP NC COASTAL SECTIONS... VERY LIGHT DIFFLUENT LOW LEVEL FLOW SHOULD PERSIST OVER CENTRAL NC... AND THUS TEMPS SHOULD STRUGGLE TO RISE. HAVE TRIMMED BACK HIGHS TO THE UPPER 30S TO MID 40S... AND EVEN THIS MAY BE OPTIMISTIC. HAVE MADE ADJUSTMENTS TO TEMPERATURES THROUGH TONIGHT AS WELL... TO SHOW THEM HOLDING FAIRLY STEADY OVERNIGHT. -GIH && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... AS OF 230 AM FRIDAY... STILL MORE ENERGY NOW COMING ACROSS THE BAJA AND NRN MEXICO FLOWS THROUGH THE SOUTHERN STREAM ACROSS THE SRN CONUS. THIS INDUCES SMALL SCALE PERTURBATIONS AND WEAK LOW PRESSURE WAVES ALONG A STATIONARY FRONT TO OUR SOUTH THROUGH EARLY SAT. EXTENSIVE CLOUDINESS AND A MODEST THREAT OF RAIN...BUT MORE LIKELY DRIZZLE WITH AREAS OF LOW STRATUS AND FOG ESPECIALLY IN THE DENSE RAIN- COOLED PIEDMONT AIRMASS...CAN BE EXPECTED OVERNIGHT THROUGH SAT MORNING. LITTLE CHANGE IN TEMPERATURE AND PERHAPS RISING SLIGHTLY IN THE NW IS EXPECTED...MAINLY IN THE 40S WITH LOWS 35-40 NW. SAT...A WEAK LOW OVER THE AREA AT DAYBREAK SHOULD BE SHUNTED SLOWLY SE AS HIGH PRESSURE OVER THE OHIO VALLEY BEGINS TO RIDGE INTO THE AREA FROM THE NORTH. NEAR THE SURFACE...WEAK FLOW AND LACK OF ANY FORCEFUL FLOW ACROSS THE MTNS ALLOWS LOW LEVEL MOISTURE TO LINGER. CLOUD COVER MAY BE DIFFICULT TO ERODE DURING THE DAY...WITH BREAKS MAINLY LATE IN THE DAY. THIS CONTRIBUTES TO LOW CONFIDENCE...BIG BUST POTENTIAL...IN MAX TEMPERATURE FORECASTING WITH CONSENSUS FAVORING 60S. SAT NIGHT-SUN...A SOUTHERN STREAM SHORT WAVE MAINTAINS STRENGTH AS IT TRACKS ACROSS THE CENTRAL U.S. SAT NIGHT AND ACROSS NC SUN. THERE IS LITTLE OPPORTUNITY FOR LOWER LEVEL INFLOW FROM MOISTURE SOURCE REGIONS...BUT NEAR SATURATION IS INDICATED IN THE MODELS AT MID TO UPPER LEVELS WITH A PASSING SHOWER OR SPRINKLES POSSIBLE MAINLY SUN AFTERNOON. LOWS SAT NIGHT 35-40. HIGHS SUN UPPER 40S TO LOWER 50S. -RFG && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 445 AM FRIDAY... SUN NIGHT-MON...MODEST RIDGING IN THE SOUTHERN STREAM RESULTS IN TRANSIENT HIGH PRESSURE ACROSS THE AREA WITH MILD AND DRIER AIR. AFTER LOWS 30-35 HIGHS SHOULD MODERATE TO UPPER 50S TO LOWER 60S. MON NIGHT-TUE...A TROUGH IN THE FLOW OFF THE N PAC BEGINS TO DIG A LONG WAVE TROUGH OVER THE EASTERN CONUS. THIS RESULTS IN A STRONG SURFACE LOW MOVING ACROSS THE UPPER MIDWEST AND A STRONG COLD FRONT TRAILING SOUTH AND APPROACHING THE CAROLINAS FROM THE WEST. SOUTHERLY FLOW AHEAD OF THE SYSTEM SHOULD DRAW WARM MOIST AIR FROM THE GULF. EXPECT INCREASING CLOUDINESS AND A CHANCE OF SHOWERS BY LATE TUE. LOWS IN THE 40S. HIGHS IN THE 60S. TUE NIGHT-WED...MODELS ARE IN FAIRLY GOOD AGREEMENT SHOWING A COLD FRONTAL PASSAGE TUE NIGHT AND ON THE COAST BY DAYBREAK WED. THE CHANCE OF SHOWERS SHOULD TAPER OFF WED MORNING...BUT WITH A VERY DEEP TROUGH AXIS TO OUR WEST...CLOUDINESS IS APT TO LINGER IN THE UNSTABLE AIR AND A SECONDARY WAVE ALONG THE FRONT COULD PUSH PCPN BACK INTO THE AREA ON WED. AT THIS PROJECTION RANGE...IT IS TOO EARLY TO TELL. LOWS 35-45 NW-SE AND HIGHS 46-53 NW-SE. WED NIGHT-THU...BELOW NORMAL TEMPERATURES ARE EXPECTED WITH A DEEP TROUGH ALONG THE EAST COAST. LOWS IN THE 20S TO LOWER 30S. HIGHS IN THE 40S TO AROUND 50. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 1255 PM FRIDAY... ONGOING IFR TO LIFR CIGS AT ALL TAF SITES ARE LIKELY TO PERSIST THROUGH SATURDAY MORNING... AND IFR TO LIFR VSBYS ARE LIKELY OVERNIGHT. THE COLD AIR DAMMING REGIME REMAINS FIRMLY ENTRENCHED ACROSS CENTRAL NC... BETWEEN THE PRIMARY SURFACE LOW NOW OVER MS AND THE COASTAL LOW NOW TRACKING UP ALONG THE NC COAST. THE MEAN FLOW ALOFT AT 1-3 KFT IS MAINLY PARALLEL TO THE SOUTHERN AND EASTERN FRINGE OF THE WEDGE FRONT... AND AS SUCH THERE IS NO MECHANISM TO DISLODGE THE FAIRLY DEEP SURFACE-BASED STABLE LAYER... SO THE CURRENT THICK LOW CLOUDS SHOULD CONTINUE. WITH AN OVERALL LACK OF ATLANTIC-SOURCE INFLOW ABOVE THE STABLE POOL... AND WITH THE PRESENCE OF A LINE OF CONVECTION FROM SRN GA THROUGH THE FL PANHANDLE HELPING TO LIMIT THE GULF-SOURCE MOISTURE TRANSPORT INTO NC... EXPECT ADDITIONAL PRECIP TO BE MOSTLY LIGHT DRIZZLE... OR VERY LIGHT RAIN AT MOST AT FAY/RWI... THROUGH TONIGHT. HAVE GONE WITH PREVAILING IFR VSBY WITH AREAS OF DRIZZLE OVERNIGHT... ALTHOUGH A BRIEF DROP TO LIFR VSBY IS POSSIBLE. SURFACE WINDS SHOULD BE LIGHT AND VARIABLE... BUT PRIMARILY FROM THE N OR NNW THROUGH TONIGHT. WINDS WILL SHIFT TO WNW AND SLOWLY INCREASE TO 6-8 KTS AROUND DAYBREAK. THE COASTAL LOW WILL BEGIN TO BECOME THE DOMINANT LOW (AS THE INLAND LOW PRESSURE AREA STARTS TO FILL TO OUR WEST)... AND WILL TRACK NORTHEAST SATURDAY MORNING. WITH THIS GRADUAL EVOLUTION TO DOWNSLOPE FLOW... THE LOW CLOUDS SHOULD FINALLY BEGIN TO SLOWLY SCOUR OUT... WITH CIGS RISING TO MVFR TOWARD MIDDAY AND VSBYS RISING TO VFR. LOOKING BEYOND MIDDAY SATURDAY... THE MID LEVEL TROUGH AXIS SWINGS THROUGH SATURDAY AFTERNOON... AND PATCHY RAIN IS POSSIBLE AT FAY WITH A CHANCE FOR IFR CIGS ONCE AGAIN THERE. HIGH PRESSURE TRIES TO BUILD IN BEHIND THE DEPARTING LOW SATURDAY NIGHT... HOWEVER WITH PERSISTENT BOUNDARY LAYER MOISTURE AND A LINGERING SURFACE TROUGH BACK INTO CENTRAL NC... IFR CIGS MAY RETURN ESPECIALLY AT RDU/RWI/FAY... AND THESE MAY LAST INTO SUNDAY MORNING WITH MODEL INDICATIONS OF A NE TO E BOUNDARY LAYER FLOW. MVFR FOG IS POSSIBLE SUNDAY NIGHT WITH WEAK LOW LEVEL WINDS BENEATH THE SURFACE HIGH. OUR NEXT CHANCE AT MVFR TO IFR CIGS/VSBYS WILL ARRIVE WITH THE NEXT MID LEVEL TROUGH AND COLD FRONT LATE MONDAY NIGHT THROUGH TUESDAY. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RFG/BSD/HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...RFG LONG TERM...RFG AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1145 AM EST FRI FEB 22 2008 .SYNOPSIS... A COLD MOIST AIRMASS WILL LINGER OVER THE AREA TODAY... AS A LOW PRESSURE SYSTEM PASSES TO THE SOUTH OF THE REGION AND OFF THE COAST TONIGHT. ANOTHER WEAK LOW PRESSURE SYSTEM WILL DRIFT ACROSS THE AREA EARLY SATURDAY... THEN A COLD FRONT WILL MOVE SOUTHEAST ACROSS THE AREA SATURDAY EVENING. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1145 AM FRIDAY... THE COLD AIR DAMMING REGIME REMAINS FIRMLY ENTRENCHED ACROSS CENTRAL NC. LATEST AMDAR SOUNDINGS FROM AIRCRAFT AND 12Z REGIONAL ANALYSES AT 925 MB AND 850 MB INDICATE A RELATIVELY DEEP SURFACE-BASED STABLE LAYER CAPPED BY VERY WARM AIR ALOFT... ON THE ORDER OF +8 TO +10C. DESPITE THE PERSISTENCE OF NEAR-FREEZING SURFACE TEMPS ACROSS THE NORTHWEST PIEDMONT... HYDROMETEORS DROPPING THROUGH THIS WARMTH ALOFT ARE UNLIKELY TO GET COLD ENOUGH TO FREEZE. CALLS TO COUNTY OFFICIALS IN THIS AREA REVEAL NO PROBLEMS WITH ICING. THUS... THE ADVISORY HAS BEEN ALLOWED TO EXPIRE. PRECIPITATION COVERAGE HAS DECREASED CONSIDERABLY LATE THIS MORNING IN THE WAKE OF THE MID LEVEL WAVE NOW SHIFTING INTO EASTERN NC. WITH AN OVERALL LACK OF ATLANTIC INFLOW ABOVE THE STABLE POOL... AND THE PRESENCE OF A LINE OF CONVECTION FROM SRN GA THROUGH THE FL PANHANDLE LIMITING THE GULF-SOURCE MOISTURE TRANSPORT INTO NC... HAVE TRIMMED BACK ON POPS FOR THE REST OF THE DAY ESPECIALLY IN THE NW. EXPECT LESS THAN AN ADDITIONAL TENTH OR SO OF RAIN IN THE SE CWA WITH JUST A FEW HUNDREDTHS IN THE NW. WITH NO E OR SE WIND COMPONENT IN THE LOWEST FEW THOUSAND FEET TO HELP PUSH THE WEDGE BOUNDARY INLAND... AND MORE IMPORTANTLY WITH THE MOVEMENT OF A SURFACE LOW UP NC COASTAL SECTIONS... VERY LIGHT DIFFLUENT LOW LEVEL FLOW SHOULD PERSIST OVER CENTRAL NC... AND THUS TEMPS SHOULD STRUGGLE TO RISE. HAVE TRIMMED BACK HIGHS TO THE UPPER 30S TO MID 40S... AND EVEN THIS MAY BE OPTIMISTIC. HAVE MADE ADJUSTMENTS TO TEMPERATURES THROUGH TONIGHT AS WELL... TO SHOW THEM HOLDING FAIRLY STEADY OVERNIGHT. -GIH && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... AS OF 230 AM FRIDAY... STILL MORE ENERGY NOW COMING ACROSS THE BAJA AND NRN MEXICO FLOWS THROUGH THE SOUTHERN STREAM ACROSS THE SRN CONUS. THIS INDUCES SMALL SCALE PERTURBATIONS AND WEAK LOW PRESSURE WAVES ALONG A STATIONARY FRONT TO OUR SOUTH THROUGH EARLY SAT. EXTENSIVE CLOUDINESS AND A MODEST THREAT OF RAIN...BUT MORE LIKELY DRIZZLE WITH AREAS OF LOW STRATUS AND FOG ESPECIALLY IN THE DENSE RAIN- COOLED PIEDMONT AIRMASS...CAN BE EXPECTED OVERNIGHT THROUGH SAT MORNING. LITTLE CHANGE IN TEMPERATURE AND PERHAPS RISING SLIGHTLY IN THE NW IS EXPECTED...MAINLY IN THE 40S WITH LOWS 35-40 NW. SAT...A WEAK LOW OVER THE AREA AT DAYBREAK SHOULD BE SHUNTED SLOWLY SE AS HIGH PRESSURE OVER THE OHIO VALLEY BEGINS TO RIDGE INTO THE AREA FROM THE NORTH. NEAR THE SURFACE...WEAK FLOW AND LACK OF ANY FORCEFUL FLOW ACROSS THE MTNS ALLOWS LOW LEVEL MOISTURE TO LINGER. CLOUD COVER MAY BE DIFFICULT TO ERODE DURING THE DAY...WITH BREAKS MAINLY LATE IN THE DAY. THIS CONTRIBUTES TO LOW CONFIDENCE...BIG BUST POTENTIAL...IN MAX TEMPERATURE FORECASTING WITH CONSENSUS FAVORING 60S. SAT NIGHT-SUN...A SOUTHERN STREAM SHORT WAVE MAINTAINS STRENGTH AS IT TRACKS ACROSS THE CENTRAL U.S. SAT NIGHT AND ACROSS NC SUN. THERE IS LITTLE OPPORTUNITY FOR LOWER LEVEL INFLOW FROM MOISTURE SOURCE REGIONS...BUT NEAR SATURATION IS INDICATED IN THE MODELS AT MID TO UPPER LEVELS WITH A PASSING SHOWER OR SPRINKLES POSSIBLE MAINLY SUN AFTERNOON. LOWS SAT NIGHT 35-40. HIGHS SUN UPPER 40S TO LOWER 50S. -RFG && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 445 AM FRIDAY... SUN NIGHT-MON...MODEST RIDGING IN THE SOUTHERN STREAM RESULTS IN TRANSIENT HIGH PRESSURE ACROSS THE AREA WITH MILD AND DRIER AIR. AFTER LOWS 30-35 HIGHS SHOULD MODERATE TO UPPER 50S TO LOWER 60S. MON NIGHT-TUE...A TROUGH IN THE FLOW OFF THE N PAC BEGINS TO DIG A LONG WAVE TROUGH OVER THE EASTERN CONUS. THIS RESULTS IN A STRONG SURFACE LOW MOVING ACROSS THE UPPER MIDWEST AND A STRONG COLD FRONT TRAILING SOUTH AND APPROACHING THE CAROLINAS FROM THE WEST. SOUTHERLY FLOW AHEAD OF THE SYSTEM SHOULD DRAW WARM MOIST AIR FROM THE GULF. EXPECT INCREASING CLOUDINESS AND A CHANCE OF SHOWERS BY LATE TUE. LOWS IN THE 40S. HIGHS IN THE 60S. TUE NIGHT-WED...MODELS ARE IN FAIRLY GOOD AGREEMENT SHOWING A COLD FRONTAL PASSAGE TUE NIGHT AND ON THE COAST BY DAYBREAK WED. THE CHANCE OF SHOWERS SHOULD TAPER OFF WED MORNING...BUT WITH A VERY DEEP TROUGH AXIS TO OUR WEST...CLOUDINESS IS APT TO LINGER IN THE UNSTABLE AIR AND A SECONDARY WAVE ALONG THE FRONT COULD PUSH PCPN BACK INTO THE AREA ON WED. AT THIS PROJECTION RANGE...IT IS TOO EARLY TO TELL. LOWS 35-45 NW-SE AND HIGHS 46-53 NW-SE. WED NIGHT-THU...BELOW NORMAL TEMPERATURES ARE EXPECTED WITH A DEEP TROUGH ALONG THE EAST COAST. LOWS IN THE 20S TO LOWER 30S. HIGHS IN THE 40S TO AROUND 50. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 7 AM FRIDAY... IFR TO LIFR CONDITIONS WILL PREVAIL THROUGH TODAY AS THE RAIN COOLED PIEDMONT AIRMASS HANGS FIRM OVER CENTRAL NC. THE ONLY TERMINAL NOT AT IFR IS INT... WHICH SAW VERY LITTLE PRECIP OVERNIGHT. AS MORE PRECIP MOVES IN TODAY... EXPECT INT TO FOLLOW THE WAY OF THE OTHER TERMINALS AND DROP TO IFR CONDITIONS. A SFC LOW DEVELOPING ALONG THE SC COAST WILL TRACK NORTHEAST TODAY... HUGGING THE COAST AS IT MOVES UP THE COASTAL FRONT. THE FRONT WILL TRY TO PROGRESS INLAND... BUT IT NOW APPEARS THAT ALL OF CENTRAL NC SHOULD STAY UNDER THE RESIDUAL EFFECTS OF THE WEDGE. OCCASIONAL RAIN AND DRIZZLE WILL AFFECT THE REGION TODAY AS A SERIES OF UPPER LEVEL DISTURBANCES MOVE THROUGH. WINDS GO LIGHT AND VARIABLE TONIGHT WITH NO AIRMASS CHANGE TO SPEAK OF. THEREFORE... EXPECT CEILINGS TO DROP TO LIFR AND VSBYS TO IFR AND POSSIBLY LIFR OVERNIGHT. VFR CONDITIONS WILL RETURN SATURDAY MORNING AS THE LAST UPPER WAVE MOVES ACROSS THE AREA AND THE SURFACE LOW MOVES OFFSHORE. HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND...WITH A FAST MOVING UPPER WAVE ZIPPING ACROSS ON SUNDAY...BUT CLOUDS WILL BE OF THE ALTOCU VARIETY...HENCE CONTINUED VFR THROUGH MONDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RFG/BSD/HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...RFG LONG TERM...RFG AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1029 AM EST THU FEB 21 2008 .SYNOPSIS... COLD DRY HIGH PRESSURE WILL BUILD INTO THE REGION TODAY. A FLOW OF MOIST AIR FROM THE SOUTH WILL BEGIN TO OVERRUN THE COLDER AIR TONIGHT AS A DEVELOPING LOW PRESSURE SYSTEM APPROACHES THE CAROLINAS FROM THE SOUTHWEST. A STATIONARY FRONT WILL LINGER TO OUR SOUTH ON FRI FOLLOWED BY A COLD FRONT FROM THE WEST ON SAT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1015 AM THURSDAY... SFC ANALYSIS THIS MORNING SHOWS A COLD FRONT STRETCHING FROM WEST TO EAST ACROSS GA AND SC. 15Z TEMPS ARE IN THE MID TO UPPER 30S ACROSS CENTRAL NC WITH DEW POINTS IN THE TEENS ACROSS THE N TWO THIRDS OF THE CWA AND IN THE 20S NEAR THE SC BORDER. UPSTREAM SFC DEW POINTS WERE IN THE 5 TO 10 DEG RANGE ACROSS VA AND MD. SFC WINDS ACROSS THE PIEDMONT OF NC HAVE VEERED AND ARE MORE ENE SUGGESTING FLOW OF COLD DRY AIR FROM THE N AT THE SFC MAY BE WANING. AS H5 RIDGE AXIS MOVES E TODAY...AN UPPER LOW OVER THE DESERT SOUTHWEST WILL MOVE E TOWARD THE CENTRAL PLAINS. VIS SAT THIS MORNING SHOWS A FAIR NUMBER OF CIRRUS CONTRAILS FROM AIRCRAFT ACROSS CENTRAL NC. MORE IMPORTANTLY A CONSIDERABLE AMOUNT OF MID AND HIGH LEVEL MOISTURE UPSTREAM ACROSS THE DEEP SOUTH WILL INVADE THE REGION THIS AFTERNOON. LOW CLOUDS NEAR THE VA/NC BORDER SHOULD BECOME SCT WITH AN INCREASING CIRRUS DECK BUILDING ABOVE DURING THE DAY. EXPECT HIGH CLOUDS TO HAVE THE GREATEST COVERAGE ACROSS THE SOUTHERN TIER THIS AFTERNOON BEFORE THE WHOLE CWA BECOMES CLOUDY THIS EVE. MORNING RAOB AT KGSO THIS MORNING PROVIDED A 1000-850MB THICKNESS OF 1291 WHICH WAS A 59 M DROP FROM 00Z/20. LOCAL TEMP SCHEME WITH INCREASING CLOUDS AS NOTED ABOVE SUGGESTS HIGHS IN THE LOWER 40S ACROSS THE NORTH TO MID 40S SOUTH WHICH WILL REQUIRE FCST TEMPS TO BE BUMPED UP A DEGREE OR TWO. DEW POINT FCST HAVE BEEN UPDATED TO SHOW A TIGHT DEW POINT GRADIENT NEAR THE SC. -BLAES && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... AS OF 330 AM THURSDAY... A WINTER WEATHER ADVISORY FOR A BRIEF WINTRY MIX WITH LITTLE OR NO SNOW/SLEET ACCUMULATION TRANSITIONING TO FREEZING RAIN WITH ICE ACCUMULATIONS OF UP TO A TENTH OF AN INCH WILL BE ISSUED FOR FORSYTH...DAVIDSON...GUILFORD...ALAMANCE AND PERSON COUNTIES... VALID FROM 9 PM THIS EVENING UNTIL 9 AM FRIDAY MORNING... COMPLICATED PTYPE FORECAST FOR TONIGHT THROUGH DAYBREAK FRIDAY MORNING COURTESY OF A HYBRID CAD WEDGE AND MILLER TYPE-B CYCLOGENESIS. THE LATEST THICKNESSES OFF OF THE 00Z GFS/NAM MODEL RUNS HAVE NOT CHANGED TOO MUCH FROM PREVIOUS RUNS. THE NAM IS ABOUT 5-10 METERS COOLER THAN THE GFS DURING THE 00-12Z FRIDAY TIME FRAME. THICKNESSES OFF THE GFS/NAM DURING THE 00-12Z FRIDAY TIME-FRAME FOR WINSTON SALEM AND RALEIGH ARE AS FOLLOWS: GFS INT RDU 00Z 1294/1557 1302/1558 06Z 1305/1569 1317/1567 12Z 1324/1578 1334/1575 NAM INT RDU 00Z 1300/1549 1299/1553 06Z 1302/1562 1307/1557 12Z 1313/1571 1324/1571 AS THESE VALUES SHOW...DRAMATIC WARMING ALOFT WILL BE OCCURRING BETWEEN 00-12Z FRIDAY. FORECAST SOUNDINGS DEPICT THIS WELL...WITH A DEEP +6 TO +8 CELSIUS WARM NOSE DEVELOPING BY 06-12Z. THE THICKNESSES ALONE WOULD SUGGEST THAT PRECIP WILL BE ALL RAIN ACROSS THE ENTIRE AREA BY AROUND DAYBREAK FRIDAY MORNING...WITH MOST LOCATIONS (EXCEPT THE CLIMATOLOGICALLY FAVORED NW PIEDMONT) TRANSITIONING TO ALL RAIN WELL BEFORE THEN. THE THICKNESSES SUGGEST THAT PRECIP COULD START OUT AS A BRIEF WINTRY MIX (SNOW/SLEET) IN THE FAR NW PIEDMONT (DEPENDING ON THE ONSET...CURRENTLY 02Z OR 9 PM SEEMS REASONABLE BASED ON THE GFS/NAM QPF)...TRANSITIONING OVER TO FREEZING RAIN ONCE THE WARM NOSE STRENGTHENS AND EVAPORATIONAL COOLING DROPS SURFACE TEMPS (BY 06Z OR 1 AM)...FOLLOWED BY ALL RAIN BY OR SHORTLY AFTER SUNRISE FRIDAY MORNING. LITTLE OR NO ACCUMULATION OF SNOW/SLEET IS EXPECTED. ICE ACCUMULATIONS OF UP TO A TENTH OF AN INCH WILL BE POSSIBLE IN FORSYTH...DAVIDSON... GUILFORD...ALAMANCE AND PERSON COUNTIES WHERE FZRA WOULD HAVE THE POTENTIAL TO LAST UP TO 6-8 HOURS. FURTHER EAST AND SOUTH TOWARDS THE TRIANGLE...ALTHOUGH PRECIP MAY BEGIN AS A BRIEF PERIOD OF FREEZING RAIN...THE TRANSITION TO ALL RAIN SHOULD OCCUR QUICK ENOUGH THAT THERE WILL BE NO ICING PROBLEMS. THIS IS BECAUSE GROUND TEMPERATURES ACROSS THE REGION ARE IN THE MID TO UPPER 40S...AND ONLY ELEVATED SURFACES WOULD BE SUSCEPTIBLE TO A GLAZE OF ICE ACCRUAL BEFORE THE TRANSITION TO ALL RAIN. ELSEWHERE TO THE SOUTH AND EAST...ALL RAIN IS EXPECTED. BOTH THE GFS/NAM FCST BETWEEN 0.25" TO 0.50" OF PRECIP ACROSS THE AREA BETWEEN 00-12Z FRIDAY. A POTENTIAL PROBLEM WITH THE FORECAST IS THAT THE LATEST GFS/NAM MODEL DATA APPEARS TO BE 5-10F TOO WARM WITH DEWPOINTS PRECEDING THE ONSET OF PRECIPITATION AFTER SUNSET TONIGHT (ASSUMING THE SINGLE DIGIT DEWPOINTS FROM NORTHERN VA/WV AND PA/MD MAKE IT DOWN THIS WAY)...WHICH WOULD HAVE IMPLICATIONS ON THE LOW LEVEL THICKNESSES AND NEAR SURFACE TEMPERATURES ONCE PRECIP BEGINS AND EVAPORATIONAL COOLING OCCURS. ALTHOUGH STRONG HORIZONTAL THERMAL ADVECTION WILL BE ABSENT DUE TO THE TRANSITORY NATURE OF THE SURFACE HIGH AND MILLER TYPE B CYCLOGENESIS (NW SIDE OF DEVELOPING SURFACE LOW ALONG THE COAST)...THE MODEL MSLP FORECASTS (THE NAM IN PARTICULAR)...IN ADDITION TO HYSPLIT 10 METER BACKWARD TRAJECTORIES GENERATED OFF GFS/NAM MODEL DATA...SUGGEST THAT NEAR SFC (10 METER) FLOW THROUGH 12-15Z FRIDAY WILL ORIGINATE FROM NORTHERN VA...MD AND PA...WHICH SUGGESTS THAT THERE MAY BE WEAK HORIZONTAL THERMAL ADVECTION (COOLER/DRIER AIR FROM THE NORTH) DURING THE OVERNIGHT HOURS TONIGHT. SO...IF DEWPOINTS DO DROP INTO THE SINGLE DIGITS AND LOWER TEENS THIS AFTERNOON AND WEAK HORIZONTAL THERMAL ADVECTION (FROM THE NORTH) IS PRESENT OVERNIGHT...THEN LOCATIONS IN THE NW PIEDMONT WOULD BE MORE APT TO SEE ICING ON THE HIGHER END OF THE RANGE (0.05"-0.10")...AND LOCATIONS FURTHER EAST TOWARD THE TRIANGLE COULD POSSIBLY SEE A GLAZE OF ICE ON BRIDGES/OVERPASSES BEFORE THE TRANSITION TO ALL RAIN. WILL NEED TO MONITOR THE POSSIBILITY OF EXPANDING THE ADVISORY TO THE EAST LATER TODAY ONCE THE 12Z MODEL RUNS ARE AVAILABLE AND THE LATEST OBSERVATIONAL DATA CAN BE FACTORED IN. OTHERWISE...ONCE THE TRANSITION TO ALL RAIN OCCURS BY OR SHORTLY AFTER SUNRISE...TEMPS ARE EXPECTED TO REMAIN IN THE LOWER/MID 30S IN THE FAR NW PIEDMONT...AND RANGE FROM THE UPPER 30S TO UPPER 40S FROM THE TRIANGLE SOUTHEAST TO THE COASTAL PLAIN. PERIODS OF RAIN ARE EXPECTED TO CONTINUE THROUGHOUT THE DAY GIVEN STRONG ISENTROPIC LIFT. WIDESPREAD PRECIP AMOUNTS OF A HALF INCH TO AN INCH ARE EXPECTED ACROSS CENTRAL NC THROUGHOUT THE DAY FRIDAY. FRIDAY NIGHT AND SATURDAY...AN UPPER LEVEL SHORTWAVE IS PROGGED TO MOVE EAST THROUGH THE TN VALLEY...ALLOWING A WEAK WAVE OF LOW PRESSURE TO DEVELOP AND MOVE THROUGH THE CAROLINA COASTAL PLAIN. AT THIS TIME THE BEST CHANCE FOR PRECIP WOULD BE ALONG THE COAST...WITH MAYBE ONLY A TENTH OF AN INCH IN THE SOUTHEAST COASTAL PLAIN. LOW TEMPS SAT MORNING IN THE LOWER/MID 30S (NW) TO MID 40S (SE). HIGH TEMPS ON SATURDAY IN THE LOWER 50S (N/NW) TO LOWER 60S (S/SE). -VINCENT && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 335 AM THURSDAY... FROM AN ENERGETIC FLOW ACROSS THE N PACIFIC AND 175 KT JET ACCELERATION BETWEEN HI AND ALEUTIANS... MODELS SHOW A TRANSIENT WAVE IN THE SOUTHERN STREAM OF A SPLIT FLOW PATTERN ACROSS THE CONUS PASSING TO OUR SOUTH SAT NIGHT AND SUN. SURFACE FLOW REMAINS OUT OF THE N-NE FROM HIGH PRESSURE OVER THE UPPER OHIO VALLEY AND RELATIVELY DRY. EXPECT VARIABLE CLOUDINESS WITH A FEW SPITS POSSIBLE BUT MEASURABLE PCPN APPEARS DOUBTFUL AT THIS TIME FOR THIS FLEETING WEAKLY AMPLIFIED SYSTEM. TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL. SUN NIGHT-MON...HIGH PRESSURE AND SEASONABLE DRY AIR SHOULD MIGRATE FROM THE MIDWEST TO OFF THE EAST COAST. EXPECT MOSTLY CLEAR SKIES AND ABOUT A 25-DEG DIURNAL RANGE FROM 30S TO UPPER 50S-LOWER 60S. MON NIGHT-WED...FROM A DEEPER WAVE OVER THE WRN N PAC COMES A MORE AMPLIFIED SYSTEM THAT RESULTS IN AN ANOMALOUSLY DEEP TROUGH OVER MIDDLE EASTERN NA BY 12Z WED AS DEPICTED BY BOTH GFS AND ECMWF. THIS SHOULD RESULT IN A STRONG COLD FRONT APPROACHING THE AREA PRECEDED BY MILD MOIST SOUTHERLY FLOW AND WEAK WARM FRONTAL PASSAGE TUE. COLD FRONTAL PASSAGE IS EXPECTED EARLY WED...BUT MAY LINGER WITH A SECONDARY WAVE ALONG THE COAST TO PROLONG CLOUDINESS AND RAIN THREAT WED. POPS WILL BE KEPT IN THE CHANCE CATEGORY FOR NOW GIVEN THE LONGER TIME PROJECTION. TEMPERATURES SHOULD SURGE UPWARD ABOVE NORMAL FOR TUE AND DROP BACK TO BELOW NORMAL FOR WED WITH POTENTIAL FOR A NON-DIURNAL PATTERN OVER TUE NIGHT. -RFG && .AVIATION /15Z THURSDAY THROUGH MONDAY/... AS OF 640 AM THURSDAY... HIGH PRESSURE WITH AN COLD DRY ARCTIC AIRMASS WILL CONTINUE TO PUSH INTO THE AREA THE REMAINDER OF TODAY...RESULTING IN VFR CONDITIONS THROUGH THIS EVENING. A STRONG JET STREAM ALOFT FROM TX ACROSS THE GULF STATES WILL INDUCE NORTHWARD FLOW OF MOIST AIR OFF THE GULF AND GULF STREAM ATLANTIC OVERRUNNING THE COLDER AIR IN CENTRAL NC TONIGHT. CIGS WILL LOWER TO MVFR BY MIDNIGHT. AREAS OF PCPN WILL SPREAD FROM SW TO NE ACROSS THE REGION BETWEEN 01Z AND 05Z IN THE FORM OF RAIN AT KFAY AND FRZG RAIN AT KGSO...KINT...AND FOR A SHORTER PERIOD OF TIME AT KRDU AND KRWI. CIGS AND VSBY WILL LIKELY LOWER TO IFR OR LIFR THROUGHOUT THE AREA BY DAYBREAK AND CONTINUE IN WIDESPREAD RAIN DURING FRI. ONE LOW PRESSURE SYSTEM DEVELOPING ALONG A STATIONARY FRONT OFF SC EARLY FRI WILL BE FOLLOWED BY ANOTHER LOW PRESSURE SYSTEM CROSSING THE CENTRAL APPALACHIANS WITH A COLD FRONT TRAILING SOUTH THROUGH FRI NIGHT THE CROSSING THE AREA SAT. THIS WILL LEAD TO A PROLONGED PERIOD OF IFR CONDITIONS OVER CENTRAL NC IN STRATUS...RAIN...DRIZZLE AND FOG. CONDITIONS SHOULD IMPROVE TO VFR WITH COLD FRONTAL PASSAGE SAT AFTN. THOUGH MODELS SUGGEST A QUICK-MOVING UPPER LEVEL DISTURBANCE WITH VARIABLE CLOUDINESS ON SUNDAY...MODEL CONSENSUS FAVORS SURFACE HIGH PRESSURE WITH RELATIVELY DRY AIR MOVING FROM THE MID WEST TO THE EAST COAST SUN AND MON WITH CONDITIONS REMAINING VFR OVER CENTRAL NC. -RFG && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM EST FRIDAY FOR NCZ007-021>023-038. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...VINCENT LONG TERM...RFG AVIATION...DJF
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
900 PM PST FRI FEB 22 2008 .SYNOPSIS...SHOWERS HAVE MOVED EAST...BUT PATCHY FOG WILL LIKELY REMAIN TONIGHT ON THE COASTAL SLOPES. GUSTY WINDS THIS EVENING IN THE MOUNTAINS AND DESERTS. THERE WILL BE A BRIEF BREAK BETWEEN SYSTEMS ON SATURDAY. THE NEXT PACIFIC STORM WILL BRING MORE RAIN LATE SATURDAY NIGHT AND SUNDAY...WITH STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS. HIGH SURF WILL AFFECT THE COAST SUNDAY AFTERNOON INTO TUESDAY. FAIR AND WARMER NEXT WEEK UNDER HIGH PRESSURE. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. .SHORT TERM (TONIGHT-SUN)... THE SHOWERS HAVE MOVED EAST BUT A FAIRLY DEEP MOIST LAYER REMAINS OVER THE AREA AND THE COASTAL SLOPES OF THE MTNS WILL LIKELY SEE SOME FOG OVERNIGHT. SUBSIDENCE AND A TIGHT WESTERLY PRESSURE GRADIENT WILL CAUSE LOCALLY STRONG AND GUSTY WEST WINDS THROUGH THIS EVENING WITH LOCAL GUSTS TO 45-50 MPH IN THE MOUNTAINS AND ADJACENT DESERT SLOPES. ON SATURDAY A WEAK SHORT WAVE RIDGE WILL BRING A BREAK IN THE PRECIPITATION. RESIDUAL LOW LEVEL MOISTURE AND VARIABLE HIGH CLOUDINESS WILL KEEP SKIES PARTLY CLOUDY. THE NEXT SYSTEM WILL ARRIVE LATE SATURDAY NIGHT AND SUNDAY WITH MORE RAIN. THREE BIG CONCERNS WITH THE NEXT STORM ARE: THE POSSIBILITY OF ENOUGH MODERATE TO HEAVY RAIN...ESPECIALLY WITH THE FRONTAL PASSAGE ON SUNDAY MORNING...TO CAUSE FLASH FLOODING/MUD AND ROCK SLIDES. STRONG WINDS WITH GUSTS OVER 60 MPH IN PARTS OF THE MTNS AND DESERTS...AND FINALLY THE ARRIVAL OF VERY LARGE SURF AT THE COAST. FOR RAINFALL...CURRENT ESTIMATES ARE FOR AMOUNTS ABOUT ONE HALF TO ONE INCH IN THE COAST AND VALLEYS...AND 1 TO 3 INCHES IN FOOTHILLS AND MOUNTAINS WITH OROGRAPHIC PRECIP ENHANCEMENT ON THE WEST-FACING SLOPES. SNOW LEVEL ABOUT 6500 TO 7000 FEET. THIS NEXT ROUND OF RAIN COULD HAVE SIGNIFICANTLY HIGHER RUNOFF AMOUNTS DUE TO SATURATED SOILS FROM ANTECEDENT STORMS...AND THIS COULD INCREASE OUR POTENTIAL FOR FLOODING...MUD SLIDES AND DEBRIS FLOWS. THESE CONCERNS COULD PROMPT THE LATER ISSUANCE OF A FLASH FLOOD WATCH PARTICULARLY FOR THE BURN AREAS. FOR WINDS...EVEN STRONGER WINDS WILL ACCOMANY THE NEXT STORM WITH INCREASING SW FLOW SATURDAY NIGHT AHEAD OF THE COLD FRONT...AND ESPECIALLY ON SUNDAY WHEN STRONG WESTERLY WINDS OCCUR DURING AND AFTER FRONTAL PASSAGE. A HIGH WIND WATCH HAS BEEN POSTED FOR THE MOUNTAINS AND DESERTS WITH SOLID POTENTIAL FOR DAMAGING GUSTS OVER 60 MPH. && .LONG TERM (MON-FRI)... UPPER RIDGING AND OFFSHORE FLOW WILL BRING FAIR AND WARMER WEATHER. && .AVIATION... 230300Z...FAIRLY DEEP MOISTURE REMAINS BEHIND THE COLD FRONT THAT PASSED THROUGH THE AREA EARLIER THIS AFTERNOON. MDCRS SOUNDINGS AS WELL AS THE KNKX SOUNDING INDICATE THE TOP OF THE MOISTURE WAS BETWEEN 7000 AND 8000 FEET OVER THE AREA. EXPECT LAYERS OF BROKEN CU AND STRATOCU TO REMAIN OVER THE AREA THROUGH THE NIGHT. BASES SHOULD RANGE BETWEEN 1500 FEET TO 4000 FEET MSL. THE LOWER LAYER SHOULD BREAK UP DURING THE MORNING ON SATURDAY BUT OVERRUNNING MID AND HIGH CLOUDS...MOSTLY AT OR ABOVE FL150...SHOULD SPREAD OVER THE AREA DURING THE DAY ON SATURDAY AHEAD OF THE NEXT COLD FRONT DUE TO COME THROUGH SUNDAY MORNING. FAIRLY STRONG WEST WINDS ACROSS THE MOUNTAINS WILL RESULT IN MOUNTAIN WAVE/ROTOR ACTIVITY ALONG THE EAST SIDES OF THE MOUNTAINS OVER THE DESERT AREAS THROUGH THE EVENING VICINITY OF KPSP...KTRM AND L08. && .MARINE... NEXT MARINE THREAT WILL BE WHEN THE NEXT LOW APPROACHES FROM THE WEST SATURDAY NIGHT. WINDS LIKELY TO BE GUSTING FROM THE SOUTH OVER 25 KT WITH THIS FRONT. FOLLOWING THIS THE LARGE WEST SWELL ARRIVES...AND EXPECTED TO COME IN AS A SWELL FRONT LATE SUNDAY AFTERNOON AND EVENING WITH A RAPID INCREASE IN SEA HEIGHTS. MODELS FOR PAST FOUR DAYS HAVE CONSISTENTLY BEEN ADVERTISING HEIGHT AND TIMING AS A SOLID 16 TO 18 FEET AT 16 SECONDS BEGINNING SUNDAY EVENING AND CONTINUING INTO MONDAY MORNING THEN SLOWLY SUBSIDING TO AROUND 10 FEET MONDAY NIGHT. A COASTAL FLOOD STATEMENT REMAINS IN PLACE ADDRESSING THE THREAT OF MODERATE BEACH EROSION AND DAMAGE TO LOW LYING COASTAL STRUCTURES. ALSO ISSUED A MARINE WEATHER STATEMENT ADDRESSING THE LARGE SWELLS OVER THE COASTAL WATERS. MARINERS SHOULD ALSO BE PREPARED TO STAY OUT OR RETURN TO PORT PRIOR TO SUNDAY AFTERNOON AS ENTERING AND EXITING MOST HARBORS AND BAYS WILL LIKELY BE HAZARDOUS. && .SGX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FOR THE SAN BERNARDINO...RIVERSIDE AND SAN DIEGO COUNTY MOUNTAINS AND ADJACENT DESERTS UNTIL 1 AM PST TONIGHT. SEE LAXNPWSGX. HIGH WIND WATCH FOR THE SAN BERNARDINO...RIVERSIDE AND SAN DIEGO COUNTY MOUNTAINS AND ADJACENT DESERTS FROM SATURDAY NIGHT THROUGH SUNDAY EVENING. SEE LAXNPWSGX. COASTAL HAZARD MESSAGE FOR LATE SUNDAY AND MONDAY DUE TO UNUSUALLY HIGH SURF AND POSSIBLE BEACH EROSION. SEE LAXCFWSGX. && $$ PUBLIC...PG AVIATION...HORTON
AREA FORECAST DISCUSSION
NWS RALEIGH NC
252 AM EST SAT FEB 23 2008 .SYNOPSIS... A WEAK LOW PRESSURE WILL LINGER OVER CENTRAL AND EASTERN NORTH CAROLINA THROUGH MID AFTERNOON... BEFORE MOVING EAST. A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA THIS EVENING... SHIFTING THE WINDS TO THE NORTHEAST. A WEAK SURFACE HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT INTO SUNDAY. AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE STATE FROM THE WEST SUNDAY... BUT IT WILL REMAIN MOISTURE STARVED. && .NEAR TERM /THROUGH TODAY/... ...CONSIDERING A DENSE FOG ADVISORY FOR PORTIONS OF THE WESTERN PIEDMONT... MAINLY SW OF THE PIEDMONT TRIAD REGION MORNING... OTHERWISE SLOW CLEARING OF LOW STRATUS AND FOG EXPECTED LATE MORNING INTO THE EARLY AFTERNOON... ...RADAR TRENDS INDICATE NOTHING MORE THAN SPRINKLES FOR OUR SE COUNTIES THROUGH DAYBREAK... AS OF 245 AM SATURDAY... THE CURRENT HYBRID COLD AIR DAMMING EPISODE IS EXPECTED TO LINGER WELL INTO THE LATE MORNING HOURS. THE LINGERING LOW STATUS AND FOG WILL BE VERY SLOW TO SCOUR OUT THIS MORNING AS MODELS INDICATE LIGHT WINDS IN THE BOUNDARY LAYER INTO THE LATE MORNING. CURRENT SURFACE OBS INDICTED CEILINGS AND VISIBILITIES WERE REMAINING STATUS QUO... EXCEPT FOR LOWERING SOME OVER DAVIDSON... RANDOLPH... AND STANLY COUNTIES... WHERE WIDESPREAD VSBYS OF 1/2 TO 1 MILE WERE OBSERVED. WE WILL MONITOR THESE AREAS CLOSELY. HOWEVER... THE VISIBILITIES ARE EXPECTED TO REMAIN JUST ABOVE THE THRESHOLD FOR A DENSE FOG ADVISORY. THE 00Z/NAM WAS THE QUICKEST IN BEGINNING THE CLEARING IN THE LEE OF THE APPALACHIANS BY MID TO LATE MORNING... WITH THE GFS INDICATING THE CLEARING WILL BEGIN 3-4 HOURS LATER. GIVEN THE 00Z MODELS LACK OF ABILITY TO INITIALIZE THE SATURATED BOUNDARY LAYER OVER THE PIEDMONT DAMMING REGION...AND THE STRENGTH/DEPTH OF THE CAD (3-5K FEET) BASED ON GSO/RNK 00Z/23 SOUNDINGS... IT APPEARS REASONABLE TO FAVOR THE SLOWER CLEARING INDICATED BY THE 00Z/GFS. THIS CLEARING SHOULD GET GOING IN THE LEE OF THE BLUE RIDGE LATE MORNING AS THE DRY WESTERLY FLOW INCREASES ALOFT WITH THE PASSAGE OF THE MID LEVEL TROUGH. AS THIS TROUGH MOVES EAST THROUGH CENTRAL NC DURING THE AFTERNOON... THE CLEARING WILL SPREAD EAST. THERE SHOULD CONTINUE TO BE SCATTERED TO BROKEN STRATOCUMULUS AT 4-5K FEET EVEN AFTER THE LOWER STRATUS CLEARS OUT. THUS... WE WILL CONTINUE THE CURRENT CLOUDY FORECAST THIS MORNING... BECOMING PARTLY CLOUDY THIS AFTERNOON. THE TEMPERATURES WILL BE HIGHLY DEPENDENT ON HOW MUCH SUN DEVELOPS THIS AFTERNOON. THE PREVIOUS FORECAST (WHICH LOWERED HIGHS FOR TODAY) APPEARS VERY REASONABLE. WE WILL CONTINUE THE CURRENT MAX T FORECASTS INDICATING MID 50S NORTH CENTRAL TO LOWER 60S SE-S. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... AS OF 245 AM SATURDAY...IN THE WAKE OF THE COLD FRONTAL PASSAGE THIS EVENING... THE SKIES WILL TEMPORARILY BECOME MOSTLY CLEAR FOR MOST AREAS. THIS WILL BE FOLLOWED BY ANOTHER BOUT OF STRATUS/STRATOCUMULUS LATER TONIGHT INTO SUNDAY. THIS WILL OCCUR AS THE LOW LEVEL NE FLOW PULLS ATLANTIC MOISTURE BACK ACROSS OUR REGION. WHILE MODELS WERE GENERALLY IN AGREEMENT THAT STRATOCUMULUS WILL EVENTUALLY DEVELOP INTO OUR REGION... THE 00Z/GFS WAS MUCH FASTER IN SATURATION THE LOW LEVELS ESPECIALLY IN THE EAST OVERNIGHT... SPREADING WEST BY DAYBREAK. MOSTLY CLEAR OR PARTLY CLOUDY SKIES EARLY TONIGHT WILL BECOME OVERCAST AGAIN OVERNIGHT. WITH THIS INCREASINGLY CLOUDY PATTERN TONIGHT... THE WARMER MET STATISTICAL GUIDANCE WAS PREFERRED OVER THE GFS MOS. LOWS SHOULD REMAIN IN THE UPPER 30S TO LOWER 40S... INSTEAD OF THE COLDER LOWER 30S FORECAST BY THE GFS MOS IN THE PIEDMONT. WITH THE UPPER SHORTWAVE EXPECTED TO MOVE EAST ACROSS THE STATE DURING THE DAY SUNDAY... THE LIFT AND ASSOCIATED CLOUDINESS ALOFT WILL COMBINE WITH THE LOW LEVEL MOIST NE FLOW TO KEEP THE TEMPERATURES ON THE CHILLY SIDE. MAX T`S SUNDAY SHOULD ONLY REACH THE MID 40S NORTH TO MID 50S SOUTH. THIS UPPER SYSTEM WILL BE MOISTURE STARVED WITH LITTLE TO NO GULF INFLOW... EXPECT ONLY A CHANCE OF A FEW SPRINKLES. WE WILL ADVERTISE ONLY A SLIGHT CHANCE POP FOR ANYTHING THAT MEASURES 0.01. OTHERWISE... ONLY A FEW TRACE AMOUNTS ARE EXPECTED. THE UPPER LEVEL DISTURBANCE IS FORECAST TO SHIFT EAST SUNDAY EVENING AS WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. HOWEVER... THE FLOW AT THE SURFACE IS EXPECTED TO REMAIN WEAK... INDICATING THAT THERE SHOULD STILL BE SOME RESIDUAL LOW LEVEL MOISTURE AND CLOUDINESS TO DEAL WITH. WE WILL ADVERTISE SKIES TO BECOME PARTLY CLOUDY AS SUBSIDENCE BEHIND THE DEPARTING SHORT WAVE FAVORS CLEARING ALOFT. LOWS SHOULD STILL BE ABOVE CURRENT GUIDANCE AS THE LOW LEVEL MOISTURE SHOULD REMAIN RELATIVE HIGH. EXPECT MOSTLY MID TO UPPER 30S. HEIGHTS ARE FORECAST TO RISE ALOFT MONDAY INTO EARLY TUESDAY AHEAD OF THE NEXT SHORT WAVE TROUGH. THIS WILL BRING MILD TO WARM TEMPERATURES BACK. THE TRENDS IN THE PAST FEW RUNS HAVE BEEN TO SPEED UP THIS TROUGH AND THE ASSOCIATED COLD FRONTAL PASSAGE FOR OUR REGION (NOW APPEARS TO BE DURING THE DAY TUESDAY). THE MAIN SURFACE STORM TRACK WITH THIS TROUGH IS EXPECTED TO BE WEST TO EAST THROUGH THE OHIO VALLEY INTO THE NORTHEAST. THE ONLY SHOT AT SHOWERS FOR CENTRAL NC WILL BE WITH THE TRAILING COLD FRONT EXPECTED TUESDAY. SENSIBLE WEATHER MONDAY LOOKS TO BE DRY AND WARMER WITH HIGHS RETURNING TO THE 60S. INCREASING CLOUDINESS MONDAY NIGHT WITH A SLIGHT CHANCE OF SHOWERS TOWARD DAYBREAK (NW ONLY). LOWS WILL BE MILD WITH THE SW FLOW AND INCREASING CLOUDS (MOSTLY MID TO UPPER 40S). THE SURFACE COLD FRONT SHOULD MOVE THROUGH CENTRAL NC DURING THE DAY TUESDAY. THE BEST CHANCE OF SIGNIFICANT SHOWERS WILL BE OVER THE MOUNTAINS. WITH LIMITED DYNAMICS... AND LITTLE IN THE WAY OF BOUNDARY LAYER INSTABILITY AS THE FRONT MOVES EAST THROUGH CENTRAL NC... WE SHOULD ONLY SEE A BAND OF LIGHT SHOWERS. QPF WILL BE FORECAST AT LESS THAN 0.25 OF AN INCH. HIGHS SHOULD STILL REACH 60-65. STRONG CAA WILL BLOW ACROSS CENTRAL NC BEHIND THE COLD FRONT LATE TUESDAY AND TUESDAY NIGHT. THE SKIES WILL CLEAR RATHER ABRUPTLY AFTER THE FROPA WITH STRONG SUBSIDENCE AND DEEP NW FLOW INDICATED TUESDAY NIGHT. LOWS WILL BE LOWERED INTO THE 25-30 RANGE PER LATEST GUIDANCE. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... A TRANSIENT POSITIVE PNA PATTERN WILL DEVELOP MIDWEEK RESULTING IN A LONGWAVE TROUGH AMPLIFYING OVER THE EASTERN PORTION OF THE COUNTRY. THIS WILL BRING A RETURN OF BELOW NORMAL TEMPERATURES BY WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE PREVIOUS NIGHT`S FRONTAL PASSAGE. HIGHS WEDNESDAY SHOULD ONLY MAKE IT INTO THE UPPER 40S NORTH TO LOWER 50S SOUTH... AND WILL STRUGGLE TO MAKE IT OUT OF THE MID AND UPPER 40S ON THURSDAY. LOWS WED/THU NIGHT WILL DIP INTO THE 20S ACROSS MOST OF THE CWA. AN ALBERTA CLIPPER LOOKS POISED TO APPROACH FROM THE NORTHWEST ON FRIDAY... SENDING ANOTHER WEAK FRONT THROUGH THE AREA FRIDAY NIGHT. AS A WEAK SOUTHWEST FLOW DEVELOPS AHEAD OF THE FRONT... TEMPS ARE APT TO MODERATE SOME DURING THE DAY ON FRIDAY. HIGHS SHOULD REBOUND CLOSER TO NORMAL LEVELS IN THE LOW TO MID 50S. NO PRECIP IS EXPECTED AHEAD OF THIS FRONT GIVEN THE DRY NW FLOW REGIME. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... AS OF 1230 AM SATURDAY...IFR CONDITIONS AND OFTEN LIFR CONDITIONS DUE TO CEILINGS WILL BE IN PLACE OVERNIGHT BENEATH STRONG INVERSION THAT WILL REMAIN AROUND 2K TO 3K FEET AT LEAST THROUGH 12Z. ALTHOUGH A BIT TOO HIGH FOR LLWS...AIRCRAFT SHOULD NOTE THAT WINDS NEAR THE INVERSION...ESPECIALLY TOWARD KFAY...COULD REACH AROUND 35KT FROM THE SOUTHWEST BETWEEN 09Z AND 12Z. GRADUAL IMPROVEMENT IN CONDITIONS WILL TAKE PLACE SATURDAY...WITH VISIBILITIES EXPECTED TO BECOME VFR SATURDAY MORNING AS THE WESTERLY SURFACE FLOW INCREASES... FOLLOWED BY VFR CEILINGS MAINLY IN THE AFTERNOON IN THE DEEP...WESTERLY FLOW AS NOTED ON GFS AND NAM BUFR SOUNDINGS. LOW CEILINGS LIKELY WILL RETURN LATE SATURDAY NIGHT IN AMPLE LOW-LEVEL MOISTURE AND A NORTHEAST SURFACE FLOW THAT DEVELOPS SATURDAY NIGHT OVER CENTRAL NORTH CAROLINA BEHIND A COLD FRONT. MAINLY MID-LEVEL CLOUDS AND SPRINKLES OR PATCHY LIGHT RAIN ARE ANTICIPATED BY SUNDAY AFTERNOON WITH THE PASSAGE OF A MODERATE MID-LEVEL SHORTWAVE. AFTERWARD...THE NEXT...BEST CHANCE FOR MVFR OR EVEN IFR CONDITIONS WILL BE TUESDAY ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE STATE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT/JFB NEAR TERM...BADGETT/JFB SHORT TERM...BADGETT LONG TERM...JFB AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1237 AM EST SAT FEB 23 2008 .SYNOPSIS... COLD...MOIST AIR WILL LINGER OVER THE AREA FOR MUCH OF THE NIGHT... AS A LOW PRESSURE SYSTEM PASSES TO THE SOUTH OF THE REGION AND OFF THE COAST. ANOTHER WEAK LOW PRESSURE SYSTEM WILL DRIFT ACROSS THE AREA EARLY SATURDAY...FOLLOWED BY A COLD FRONT SATURDAY EVENING. && .NEAR TERM /THROUGH SATURDAY/... AS OF 815 PM FRIDAY...COLD-AIR DAMMING CONTINUES OVER CENTRAL NORTH CAROLINA...WITH LOW CLOUDS AND LIGHT FOG CONTINUING WITH A BREAK IN THE RAINFALL. THE BREAK IN THE RAIN SHOULD CONTINUE FOR A COUPLE OF MORE HOURS OR SO...WITH A FEW PATCHES OF DRIZZLE POSSIBLE. WATER VAPOR IMAGERY SHOWED STRONG DRYING MOVING EAST ACROSS THE GULF OF MEXICO...AND AHEAD OF THAT DRYING A WEAK SHORTWAVE WAS APPARENTLY MOVING NORTHEAST TOWARD THE CAROLINAS. THE RUC WAS HAVING DIFFICULTY RESOLVING THIS WAVE AND THE ATTENDANT INCREASE IN RAIN ACROSS CENTRAL GEORGIA...WHILE THE 18Z NAM AND GFS APPEARED TO BE MUCH CLOSER TO REALITY AND FORECAST A MODEST MID-LEVEL WAVE MOVING ACROSS THE SOUTHEAST PART OF THE STATE LATE TONIGHT. ALTHOUGH PLAN VIEW UVV IS WEAK ON BOTH THE NAM AND THE GFS...MODERATE UPPER DIFFLUENCE IS FORECAST BY BOTH BETWEEN 06Z AND 12Z ESPECIALLY SOUTHEAST ZONES WHERE THERE IS ALSO DECENT FRONTOGENESIS IN THE 700-500MB LAYER. ALL OF THIS ACCOMPANIED BY JET SUPPORT...WITH THE FRONT ENTRANCE REGION OF A 115KT 300MB JET LATE...AND NOTICEABLE DIFFLUENCE ON WATER VAPOR IMAGERY HEADED TOWARD CENTRAL NORTH CAROLINA...HAVE NUDGED THE NORTHERN EXTENT OF LIKELY POPS TO MAINLY ALONG AND SOUTH OF A LINE FROM KMEB TO KGSB...WHERE THE SREF HAS THE GREATEST CHANCES OF MEASURABLE RAIN OVERNIGHT. EXCEPT FOR THE TRIAD...FARTHEST AWAY FROM THE LIFT AND JET SUPPORT...LEFT SLIGHT CHANCES FOR RAIN. ELSEWHERE...INCREASED THE CHANCES FOR RAIN BY ABOUT 10 PERCENT. WHATEVER RAIN FALLS OVERNIGHT SHOULD NOT MEASURE MUCH AS THE SREF SHOWS THE CHANCES FOR RAIN AT OR ABOVE A QUARTER INCH TO BE ESSENTIALLY ZERO. TEMPERATURES WILL REMAIN NEARLY STEADY...THOUGH DO EXPECT SOME WARM DEW POINT ADVECTION LATE TONIGHT WHICH WILL HELP TO BOOST TEMPERATURES ON AVERAGE ABOUT A CATEGORY BY MORNING. AREAS OF FOG WILL PERSIST PARTICULARLY ALONG AND NORTH OF U.S. 64 AND MOST ESPECIALLY TOWARD THE VIRGINIA BORDER WHERE SURFACE TEMPERATURES ARE COOLER. AT LEAST PATCHY FOG SHOULD PERSIST INTO EARLY SATURDAY MORNING. FORECAST SOUNDINGS SHOW A VERY GRADUAL DISSOLUTION OF THE LOW LEVEL MOIST AND STABLE AIR SATURDAY. THIS SEEMS REASONABLE CONSIDERING THE MID LEVEL FLOW REMAINS FROM THE SOUTHWEST UNTIL MID LEVEL TROUGH AXIS PASSAGE LATE IN THE DAY...AND A LINGERING SURFACE TROUGH EXTENDING FROM THE OFFSHORE LOW BACK INTO NC APPEARS LIKELY. HAVE GONE WITH A SLOW TRANSITION FROM CLOUDY IN THE MORNING WITH PATCHES OF DRIZZLE...TO PARTLY CLOUDY BY LATE IN THE AFTERNOON. A FEW SPRINKLES COULD OCCUR WITH THE MID LEVEL TROUGH PASSAGE...BUT LIFT IS OVERALL FAIRLY WEAK. DUE TO THE PERSISTENT CLOUDS...A FEW DEGREES HAVE BEEN SHAVED OFF SATURDAY HIGHS...WHICH ARE EXPECTED TO BE 56-64...IN LINE WITH THE RECENT LOWERING TREND OF GFS MOS GUIDANCE NUMBERS. IF THE CLOUDS LINGER LONGER THAN EXPECTED... EVEN THESE MAY BE A FEW DEGREES TOO HIGH. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 245 PM FRIDAY...IN THE WAKE OF THE COLD FRONT TEMPERATURES SUNDAY WILL BE SIGNIFICANTLY COOLER THAN SATURDAY AND WITH THE UPPER SHORTWAVE MOVING EAST ACROSS THE AREA ALONG WITH SOME MID LEVEL MOISTURE EXPECT THE MID AND HIGH CLOUDS TO HANG IN THROUGHOUT THE DAY. HAVE LOWERED THE CHANCE OF RAIN SUNDAY TO A SLIGHT CHANCE DUE TO THE LACK OF LOW LEVEL MOISTURE AND ZONAL WESTERLY ABOVE 850 MB. SUNDAY NIGHT WILL BE THE COLDEST WITH THIS NEXT FRONTAL PASSAGE AND THE AMOUNT OF CLOUD COVER AND HOW FAST SKIES CLEAR WILL DETERMINE HOW COLD OVERNIGHT LOWS DROP BY MONDAY MORNING. THE HIGH SETTLING IN OVERHEAD SUNDAY NIGHT AND MONDAY MORNING WILL THE THE COLDEST NIGHTS WITH THIS NEXT AIRMASS WITH LOWS IN THE LOW TO MID 30S. CLOUDS BREAK A LITTLE FOR MONDAY ALLOWING FOR TEMPERATURES TO REBOUND A LITTLE AS THE FLOW BECOMES MORE SOUTHERLY. WEAK RETURN FLOW STARTS TO DEVELOP MONDAY AS THE SURFACE HIGH MOVES OFFSHORE LATE IN THE DAY MONDAY AND A STRONG AREA OF LOW PRESSURE MOVES INTO THE OHIO RIVER VALLEY. WITH PERIODS OF SUNSHINE EXPECTED MONDAY HIGHS WILL WARM BACK TO AROUND 60. BY MONDAY NIGHT THE SOUTHWESTERLY FLOW INCREASES AT 850 MB WHILE MID AND HIGH LEVEL MOISTURE STREAMS IN FROM THE WEST. SOUTHWEST FLOW INCREASES TO 50KT OFF THE SURFACE ON TUESDAY RESULTING IN SOME WINDY CONDITIONS AND ENOUGH LOW LEVEL MOISTURE TO PROVIDE SCATTERED SHOWERS AHEAD AND ALONG THE COLD FROM WHICH WILL MOVE THROUGH THE AREA MID TO LATE TUESDAY AFTERNOON. RIGHT NOW INSTABILITY LOOKS LIMITED AND AS WITH PAST SYSTEM AND MOST OF THE DYNAMICS PASS TO OUR NORTH HOWEVER THE WIND FIELDS ARE IMPRESSIVE. EITHER WAY IT LOOKS AS THOUGH THE AREA WILL SEE A DECENT CHANCE OF RAIN TUESDAY, BUT OVERALL RAINFALL AMOUNTS DUE NOT LOOK IMPRESSIVE DUE TO THE FAST MOVING NATURE OF THE SYSTEM AND RELATIVELY SHORT DURATION OF RAINFALL. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 245 PM FRIDAY...BELOW NORMAL TEMPERATURES AND DRY CONDITIONS EXPECTED FOR THE MIDDLE AND END OF NEXT WEEK. AFTER A QUICK SHOT OF RAIN TUESDAY CONDITIONS DRY OUT QUICKLY BY WEDNESDAY AS VERY COLD AIR SURGES SOUTH WEDNESDAY AFTERNOON AND INTO THURSDAY. A RETURN TO LOWS IN THE 20S IS AROUND THE CORNER WEDNESDAY NIGHT AND THURSDAY NIGHT. CONDITIONS WILL LIKELY BE A BIT BREEZY WEDNESDAY AFTERNOON AS THE DRY COLD AIR SURGES SOUTH. WINDS SHOULD BE A LITTLE LIGHTER SOME THURSDAY AFTERNOON. MODELS SUGGEST A FAST MOVING CLIPPER SYSTEM WILL APPROACH FROM THE WEST LATE FRIDAY AND THIS COULD RESULT IN AN INCREASE IN THE MID AND HIGH CLOUDS BUT NO REAL CHANCE OF RAIN. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 1230 AM SATURDAY...IFR CONDITIONS AND OFTEN LIFR CONDITIONS DUE TO CEILINGS WILL BE IN PLACE OVERNIGHT BENEATH STRONG INVERSION THAT WILL REMAIN AROUND 2K TO 3K FEET AT LEAST THROUGH 12Z. ALTHOUGH A BIT TOO HIGH FOR LLWS...AIRCRAFT SHOULD NOTE THAT WINDS NEAR THE INVERSION...ESPECIALLY TOWARD KFAY...COULD REACH AROUND 35KT FROM THE SOUTHWEST BETWEEN 09Z AND 12Z. GRADUAL IMPROVEMENT IN CONDITIONS WILL TAKE PLACE SATURDAY...WITH VISIBILITIES EXPECTED TO BECOME VFR SATURDAY MORNING AS THE WESTERLY SURFACE FLOW INCREASES... FOLLOWED BY VFR CEILINGS MAINLY IN THE AFTERNOON IN THE DEEP...WESTERLY FLOW AS NOTED ON GFS AND NAM BUFR SOUNDINGS. LOW CEILINGS LIKELY WILL RETURN LATE SATURDAY NIGHT IN AMPLE LOW-LEVEL MOISTURE AND A NORTHEAST SURFACE FLOW THAT DEVELOPS SATURDAY NIGHT OVER CENTRAL NORTH CAROLINA BEHIND A COLD FRONT. MAINLY MID-LEVEL CLOUDS AND SPRINKLES OR PATCHY LIGHT RAIN ARE ANTICIPATED BY SUNDAY AFTERNOON WITH THE PASSAGE OF A MODERATE MID-LEVEL SHORTWAVE. AFTERWARD...THE NEXT...BEST CHANCE FOR MVFR OR EVEN IFR CONDITIONS WILL BE TUESDAY ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE STATE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF/HARTFIELD SHORT TERM...JO LONG TERM...JO AVIATION...DJF/JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1005 AM EST SAT FEB 23 2008 .SYNOPSIS... WEAK LOW PRESSURE WILL LINGER OVER CENTRAL AND EASTERN NORTH CAROLINA BEFORE MOVING EAST THIS AFTERNOON. A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA THIS EVENING... AND THEN A WEAK HIGH PRESSURE AREAS WILL BUILD OVERHEAD LATE TONIGHT THROUGH SUNDAY. AN UPPER LEVEL DISTURBANCE WILL ZIP QUICKLY OVERHEAD SUNDAY AFTERNOON. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM SATURDAY... THE DENSE FOG ADVISORY HAS BEEN ALLOWED TO EXPIRE. AS OF 905 AM SATURDAY... SCATTERED THUNDERSTORMS PERSIST OVER THE NORTHERN PIEDMONT AND COASTAL PLAIN... ALONG A WEAK SURFACE LOW PRESSURE TROUGH. NAM BUFR SOUNDINGS AND THE SPC MESOANALYSIS PAGE INDICATE ELEVATED INSTABILITY ABOVE 900 MB WITH MID LEVEL LAPSE RATES OVER 7.0 C/KM PUSHING IN FROM THE WEST ASSOCIATED WITH A COLD FRONT ALOFT. UPPER LEVEL POSITIVE POTENTIAL VORTICITY ADVECTION AND RIGHT ENTRANCE REGION DYNAMICS WITH THE 130+ KT UPPER JET TO OUR N ARE LIKELY ALSO CONTRIBUTING TO FORCING FOR ASCENT SUPPORTING THIS CONVECTION. HAVE EXTENDED THE RISK OF SHOWERS AND THUNDERSTORMS FOR ANOTHER COUPLE OF HOURS... UNTIL THESE FORCING FEATURES EXIT TO THE NORTHEAST. BASED ON THE FACT THAT THE LOW LEVEL SATURATED DECK IS NEARLY A HALF KM DEEP AND THE LOW LEVEL WIND FIELD SHOULD REMAIN WEAK THROUGH EARLY AFTERNOON AT LEAST... THESE CLOUDS SHOULD BE TOUGH TO DISLODGE WITH ANY SWIFTNESS. HAVE SLOWED THE SKY CLEARING BY SEVERAL HOURS. HAVE ALSO DROPPED HIGHS TODAY BY A FEW DEGREES... TO 56-62... AND EVEN THESE MAY BE TOO HIGH ESPECIALLY IN THE NE CWA. -GIH PREVIOUS DISCUSSION FOLLOWS... THE BACK EDGE OF THE MID AND HIGH LEVEL MOISTURE WAS MOVING EAST OVER THE PIEDMONT. THIS MAY AID IN THE FOG BECOMING MORE DENSE THROUGH DAYBREAK OVER THE WESTERN AND SOUTHERN PIEDMONT... AND POSSIBLY THE SANDHILLS. THEREFORE... WE WILL ISSUE A DENSE FOG ADVISORY FOR AREAS ALONG AND WEST GREENSBORO TO FAYETTEVILLE THROUGH 1000 AM. AS OF 245 AM SATURDAY... THE CURRENT HYBRID COLD AIR DAMMING EPISODE IS EXPECTED TO LINGER WELL INTO THE LATE MORNING HOURS. THE LINGERING LOW STATUS AND FOG WILL BE VERY SLOW TO SCOUR OUT THIS MORNING AS MODELS INDICATE LIGHT WINDS IN THE BOUNDARY LAYER INTO THE LATE MORNING. CURRENT SURFACE OBS INDICTED CEILINGS AND VISIBILITIES WERE REMAINING STATUS QUO... EXCEPT FOR LOWERING SOME OVER DAVIDSON... RANDOLPH... AND STANLY COUNTIES... WHERE WIDESPREAD VSBYS OF 1/2 TO 1 MILE WERE OBSERVED. WE WILL MONITOR THESE AREAS CLOSELY. HOWEVER... THE VISIBILITIES ARE EXPECTED TO REMAIN JUST ABOVE THE THRESHOLD FOR A DENSE FOG ADVISORY. THE 00Z/NAM WAS THE QUICKEST IN BEGINNING THE CLEARING IN THE LEE OF THE APPALACHIANS BY MID TO LATE MORNING... WITH THE GFS INDICATING THE CLEARING WILL BEGIN 3-4 HOURS LATER. GIVEN THE 00Z MODELS LACK OF ABILITY TO INITIALIZE THE SATURATED BOUNDARY LAYER OVER THE PIEDMONT DAMMING REGION...AND THE STRENGTH/DEPTH OF THE CAD (3-5K FEET) BASED ON GSO/RNK 00Z/23 SOUNDINGS... IT APPEARS REASONABLE TO FAVOR THE SLOWER CLEARING INDICATED BY THE 00Z/GFS. THIS CLEARING SHOULD GET GOING IN THE LEE OF THE BLUE RIDGE LATE MORNING AS THE DRY WESTERLY FLOW INCREASES ALOFT WITH THE PASSAGE OF THE MID LEVEL TROUGH. AS THIS TROUGH MOVES EAST THROUGH CENTRAL NC DURING THE AFTERNOON... THE CLEARING WILL SPREAD EAST. THERE SHOULD CONTINUE TO BE SCATTERED TO BROKEN STRATOCUMULUS AT 4-5K FEET EVEN AFTER THE LOWER STRATUS CLEARS OUT. THUS... WE WILL CONTINUE THE CURRENT CLOUDY FORECAST THIS MORNING... BECOMING PARTLY CLOUDY THIS AFTERNOON. THE TEMPERATURES WILL BE HIGHLY DEPENDENT ON HOW MUCH SUN DEVELOPS THIS AFTERNOON. THE PREVIOUS FORECAST (WHICH LOWERED HIGHS FOR TODAY) APPEARS VERY REASONABLE. WE WILL CONTINUE THE CURRENT MAX T FORECASTS INDICATING MID 50S NORTH CENTRAL TO LOWER 60S SE-S.-PWB && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 245 AM SATURDAY...IN THE WAKE OF THE COLD FRONTAL PASSAGE THIS EVENING... THE SKIES WILL TEMPORARILY BECOME MOSTLY CLEAR FOR MOST AREAS. THIS WILL BE FOLLOWED BY ANOTHER BOUT OF STRATUS/STRATOCUMULUS LATER TONIGHT INTO SUNDAY. THIS WILL OCCUR AS THE LOW LEVEL NE FLOW PULLS ATLANTIC MOISTURE BACK ACROSS OUR REGION. WHILE MODELS WERE GENERALLY IN AGREEMENT THAT STRATOCUMULUS WILL EVENTUALLY DEVELOP INTO OUR REGION... THE 00Z/GFS WAS MUCH FASTER IN SATURATION THE LOW LEVELS ESPECIALLY IN THE EAST OVERNIGHT... SPREADING WEST BY DAYBREAK. MOSTLY CLEAR OR PARTLY CLOUDY SKIES EARLY TONIGHT WILL BECOME OVERCAST AGAIN OVERNIGHT. WITH THIS INCREASINGLY CLOUDY PATTERN TONIGHT... THE WARMER MET STATISTICAL GUIDANCE WAS PREFERRED OVER THE GFS MOS. LOWS SHOULD REMAIN IN THE UPPER 30S TO LOWER 40S... INSTEAD OF THE COLDER LOWER 30S FORECAST BY THE GFS MOS IN THE PIEDMONT. WITH THE UPPER SHORTWAVE EXPECTED TO MOVE EAST ACROSS THE STATE DURING THE DAY SUNDAY... THE LIFT AND ASSOCIATED CLOUDINESS ALOFT WILL COMBINE WITH THE LOW LEVEL MOIST NE FLOW TO KEEP THE TEMPERATURES ON THE CHILLY SIDE. MAX T`S SUNDAY SHOULD ONLY REACH THE MID 40S NORTH TO MID 50S SOUTH. THIS UPPER SYSTEM WILL BE MOISTURE STARVED WITH LITTLE TO NO GULF INFLOW... EXPECT ONLY A CHANCE OF A FEW SPRINKLES. WE WILL ADVERTISE ONLY A SLIGHT CHANCE POP FOR ANYTHING THAT MEASURES 0.01. OTHERWISE... ONLY A FEW TRACE AMOUNTS ARE EXPECTED. THE UPPER LEVEL DISTURBANCE IS FORECAST TO SHIFT EAST SUNDAY EVENING AS WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. HOWEVER... THE FLOW AT THE SURFACE IS EXPECTED TO REMAIN WEAK... INDICATING THAT THERE SHOULD STILL BE SOME RESIDUAL LOW LEVEL MOISTURE AND CLOUDINESS TO DEAL WITH. WE WILL ADVERTISE SKIES TO BECOME PARTLY CLOUDY AS SUBSIDENCE BEHIND THE DEPARTING SHORT WAVE FAVORS CLEARING ALOFT. LOWS SHOULD STILL BE ABOVE CURRENT GUIDANCE AS THE LOW LEVEL MOISTURE SHOULD REMAIN RELATIVE HIGH. EXPECT MOSTLY MID TO UPPER 30S. HEIGHTS ARE FORECAST TO RISE ALOFT MONDAY INTO EARLY TUESDAY AHEAD OF THE NEXT SHORT WAVE TROUGH. THIS WILL BRING MILD TO WARM TEMPERATURES BACK. THE TRENDS IN THE PAST FEW RUNS HAVE BEEN TO SPEED UP THIS TROUGH AND THE ASSOCIATED COLD FRONTAL PASSAGE FOR OUR REGION (NOW APPEARS TO BE DURING THE DAY TUESDAY). THE MAIN SURFACE STORM TRACK WITH THIS TROUGH IS EXPECTED TO BE WEST TO EAST THROUGH THE OHIO VALLEY INTO THE NORTHEAST. THE ONLY SHOT AT SHOWERS FOR CENTRAL NC WILL BE WITH THE TRAILING COLD FRONT EXPECTED TUESDAY. SENSIBLE WEATHER MONDAY LOOKS TO BE DRY AND WARMER WITH HIGHS RETURNING TO THE 60S. INCREASING CLOUDINESS MONDAY NIGHT WITH A SLIGHT CHANCE OF SHOWERS TOWARD DAYBREAK (NW ONLY). LOWS WILL BE MILD WITH THE SW FLOW AND INCREASING CLOUDS (MOSTLY MID TO UPPER 40S). THE SURFACE COLD FRONT SHOULD MOVE THROUGH CENTRAL NC DURING THE DAY TUESDAY. THE BEST CHANCE OF SIGNIFICANT SHOWERS WILL BE OVER THE MOUNTAINS. WITH LIMITED DYNAMICS... AND LITTLE IN THE WAY OF BOUNDARY LAYER INSTABILITY AS THE FRONT MOVES EAST THROUGH CENTRAL NC... WE SHOULD ONLY SEE A BAND OF LIGHT SHOWERS. QPF WILL BE FORECAST AT LESS THAN 0.25 OF AN INCH. HIGHS SHOULD STILL REACH 60-65. STRONG CAA WILL BLOW ACROSS CENTRAL NC BEHIND THE COLD FRONT LATE TUESDAY AND TUESDAY NIGHT. THE SKIES WILL CLEAR RATHER ABRUPTLY AFTER THE FROPA WITH STRONG SUBSIDENCE AND DEEP NW FLOW INDICATED TUESDAY NIGHT. LOWS WILL BE LOWERED INTO THE 25-30 RANGE PER LATEST GUIDANCE. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... A TRANSIENT POSITIVE PNA PATTERN WILL DEVELOP MIDWEEK RESULTING IN A LONGWAVE TROUGH AMPLIFYING OVER THE EASTERN PORTION OF THE COUNTRY. THIS WILL BRING A RETURN OF BELOW NORMAL TEMPERATURES BY WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE PREVIOUS NIGHT`S FRONTAL PASSAGE. HIGHS WEDNESDAY SHOULD ONLY MAKE IT INTO THE UPPER 40S NORTH TO LOWER 50S SOUTH... AND WILL STRUGGLE TO MAKE IT OUT OF THE MID AND UPPER 40S ON THURSDAY. LOWS WED/THU NIGHT WILL DIP INTO THE 20S ACROSS MOST OF THE CWA. AN ALBERTA CLIPPER LOOKS POISED TO APPROACH FROM THE NORTHWEST ON FRIDAY... SENDING ANOTHER WEAK FRONT THROUGH THE AREA FRIDAY NIGHT. AS A WEAK SOUTHWEST FLOW DEVELOPS AHEAD OF THE FRONT... TEMPS ARE APT TO MODERATE SOME DURING THE DAY ON FRIDAY. HIGHS SHOULD REBOUND CLOSER TO NORMAL LEVELS IN THE LOW TO MID 50S. NO PRECIP IS EXPECTED AHEAD OF THIS FRONT GIVEN THE DRY NW FLOW REGIME. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 640 AM SATURDAY... LIFR/IFR CONDITIONS WILL CONTINUE THROUGH THE EARLY MORNING BENEATH A STRONG INVERSION THAT WILL REMAIN AROUND 2K TO 3K FEET THROUGH MOST OF THE MORNING. ALTHOUGH A BIT TOO HIGH FOR LLWS...AIRCRAFT SHOULD NOTE THAT WINDS NEAR THE INVERSION WILL REACH AROUND 35KT FROM THE SOUTHWEST THROUGH 15Z WHILE SFC WINDS REMAIN LIGHT AND VARIABLE. GRADUAL IMPROVEMENT IN CONDITIONS WILL TAKE PLACE TODAY WITH VISIBILITIES EXPECTED TO BECOME VFR SATURDAY AFTERNOON AS THE WESTERLY SURFACE FLOW INCREASES. THE LATEST GUIDANCE HAS DELAYED THE CLEARING OF MVFR/IFR CEILINGS UNTIL LATE THIS AFTERNOON. THIS IS EVEN WITH THE MODELS NOT FULLING CAPTURING THE FULL EXTENT OF LOW LEVEL SATURATION SEEN ON THE 00Z/23 GSO SOUNDING. THEREFORE...HAVE DELAYED VFR CIGS UNTIL LATE AFTERNOON. LOW CEILINGS LIKELY WILL RETURN LATE SATURDAY NIGHT IN AMPLE LOW-LEVEL MOISTURE AND A NORTHEAST SURFACE FLOW THAT DEVELOPS SATURDAY NIGHT OVER CENTRAL NORTH CAROLINA BEHIND A COLD FRONT. MAINLY MID-LEVEL CLOUDS AND SPRINKLES OR PATCHY LIGHT RAIN ARE ANTICIPATED BY SUNDAY AFTERNOON WITH THE PASSAGE OF A MODERATE MID-LEVEL SHORTWAVE. AFTERWARD...THE NEXT...BEST CHANCE FOR MVFR OR EVEN IFR CONDITIONS WILL BE TUESDAY ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE STATE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...BADGETT LONG TERM...JFB AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
905 AM EST SAT FEB 23 2008 .SYNOPSIS... WEAK LOW PRESSURE WILL LINGER OVER CENTRAL AND EASTERN NORTH CAROLINA BEFORE MOVING EAST THIS AFTERNOON. A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA THIS EVENING... AND THEN A WEAK HIGH PRESSURE AREAS WILL BUILD OVERHEAD LATE TONIGHT THROUGH SUNDAY. AN UPPER LEVEL DISTURBANCE WILL ZIP QUICKLY OVERHEAD SUNDAY AFTERNOON. && .NEAR TERM /THROUGH TONIGHT/... AS OF 905 AM SATURDAY... SCATTERED THUNDERSTORMS PERSIST OVER THE NORTHERN PIEDMONT AND COASTAL PLAIN... ALONG A WEAK SURFACE LOW PRESSURE TROUGH. NAM BUFR SOUNDINGS AND THE SPC MESOANALYSIS PAGE INDICATE ELEVATED INSTABILITY ABOVE 900 MB WITH MID LEVEL LAPSE RATES OVER 7.0 C/KM PUSHING IN FROM THE WEST ASSOCIATED WITH A COLD FRONT ALOFT. UPPER LEVEL POSITIVE POTENTIAL VORTICITY ADVECTION AND RIGHT ENTRANCE REGION DYNAMICS WITH THE 130+ KT UPPER JET TO OUR N ARE LIKELY ALSO CONTRIBUTING TO FORCING FOR ASCENT SUPPORTING THIS CONVECTION. HAVE EXTENDED THE RISK OF SHOWERS AND THUNDERSTORMS FOR ANOTHER COUPLE OF HOURS... UNTIL THESE FORCING FEATURES EXIT TO THE NORTHEAST. BASED ON THE FACT THAT THE LOW LEVEL SATURATED DECK IS NEARLY A HALF KM DEEP AND THE LOW LEVEL WIND FIELD SHOULD REMAIN WEAK THROUGH EARLY AFTERNOON AT LEAST... THESE CLOUDS SHOULD BE TOUGH TO DISLODGE WITH ANY SWIFTNESS. HAVE SLOWED THE SKY CLEARING BY SEVERAL HOURS. HAVE ALSO DROPPED HIGHS TODAY BY A FEW DEGREES... TO 56-62... AND EVEN THESE MAY BE TOO HIGH ESPECIALLY IN THE NE CWA. -GIH PREVIOUS DISCUSSION FOLLOWS... THE BACK EDGE OF THE MID AND HIGH LEVEL MOISTURE WAS MOVING EAST OVER THE PIEDMONT. THIS MAY AID IN THE FOG BECOMING MORE DENSE THROUGH DAYBREAK OVER THE WESTERN AND SOUTHERN PIEDMONT... AND POSSIBLY THE SANDHILLS. THEREFORE... WE WILL ISSUE A DENSE FOG ADVISORY FOR AREAS ALONG AND WEST GREENSBORO TO FAYETTEVILLE THROUGH 1000 AM. AS OF 245 AM SATURDAY... THE CURRENT HYBRID COLD AIR DAMMING EPISODE IS EXPECTED TO LINGER WELL INTO THE LATE MORNING HOURS. THE LINGERING LOW STATUS AND FOG WILL BE VERY SLOW TO SCOUR OUT THIS MORNING AS MODELS INDICATE LIGHT WINDS IN THE BOUNDARY LAYER INTO THE LATE MORNING. CURRENT SURFACE OBS INDICTED CEILINGS AND VISIBILITIES WERE REMAINING STATUS QUO... EXCEPT FOR LOWERING SOME OVER DAVIDSON... RANDOLPH... AND STANLY COUNTIES... WHERE WIDESPREAD VSBYS OF 1/2 TO 1 MILE WERE OBSERVED. WE WILL MONITOR THESE AREAS CLOSELY. HOWEVER... THE VISIBILITIES ARE EXPECTED TO REMAIN JUST ABOVE THE THRESHOLD FOR A DENSE FOG ADVISORY. THE 00Z/NAM WAS THE QUICKEST IN BEGINNING THE CLEARING IN THE LEE OF THE APPALACHIANS BY MID TO LATE MORNING... WITH THE GFS INDICATING THE CLEARING WILL BEGIN 3-4 HOURS LATER. GIVEN THE 00Z MODELS LACK OF ABILITY TO INITIALIZE THE SATURATED BOUNDARY LAYER OVER THE PIEDMONT DAMMING REGION...AND THE STRENGTH/DEPTH OF THE CAD (3-5K FEET) BASED ON GSO/RNK 00Z/23 SOUNDINGS... IT APPEARS REASONABLE TO FAVOR THE SLOWER CLEARING INDICATED BY THE 00Z/GFS. THIS CLEARING SHOULD GET GOING IN THE LEE OF THE BLUE RIDGE LATE MORNING AS THE DRY WESTERLY FLOW INCREASES ALOFT WITH THE PASSAGE OF THE MID LEVEL TROUGH. AS THIS TROUGH MOVES EAST THROUGH CENTRAL NC DURING THE AFTERNOON... THE CLEARING WILL SPREAD EAST. THERE SHOULD CONTINUE TO BE SCATTERED TO BROKEN STRATOCUMULUS AT 4-5K FEET EVEN AFTER THE LOWER STRATUS CLEARS OUT. THUS... WE WILL CONTINUE THE CURRENT CLOUDY FORECAST THIS MORNING... BECOMING PARTLY CLOUDY THIS AFTERNOON. THE TEMPERATURES WILL BE HIGHLY DEPENDENT ON HOW MUCH SUN DEVELOPS THIS AFTERNOON. THE PREVIOUS FORECAST (WHICH LOWERED HIGHS FOR TODAY) APPEARS VERY REASONABLE. WE WILL CONTINUE THE CURRENT MAX T FORECASTS INDICATING MID 50S NORTH CENTRAL TO LOWER 60S SE-S.-PWB && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 245 AM SATURDAY...IN THE WAKE OF THE COLD FRONTAL PASSAGE THIS EVENING... THE SKIES WILL TEMPORARILY BECOME MOSTLY CLEAR FOR MOST AREAS. THIS WILL BE FOLLOWED BY ANOTHER BOUT OF STRATUS/STRATOCUMULUS LATER TONIGHT INTO SUNDAY. THIS WILL OCCUR AS THE LOW LEVEL NE FLOW PULLS ATLANTIC MOISTURE BACK ACROSS OUR REGION. WHILE MODELS WERE GENERALLY IN AGREEMENT THAT STRATOCUMULUS WILL EVENTUALLY DEVELOP INTO OUR REGION... THE 00Z/GFS WAS MUCH FASTER IN SATURATION THE LOW LEVELS ESPECIALLY IN THE EAST OVERNIGHT... SPREADING WEST BY DAYBREAK. MOSTLY CLEAR OR PARTLY CLOUDY SKIES EARLY TONIGHT WILL BECOME OVERCAST AGAIN OVERNIGHT. WITH THIS INCREASINGLY CLOUDY PATTERN TONIGHT... THE WARMER MET STATISTICAL GUIDANCE WAS PREFERRED OVER THE GFS MOS. LOWS SHOULD REMAIN IN THE UPPER 30S TO LOWER 40S... INSTEAD OF THE COLDER LOWER 30S FORECAST BY THE GFS MOS IN THE PIEDMONT. WITH THE UPPER SHORTWAVE EXPECTED TO MOVE EAST ACROSS THE STATE DURING THE DAY SUNDAY... THE LIFT AND ASSOCIATED CLOUDINESS ALOFT WILL COMBINE WITH THE LOW LEVEL MOIST NE FLOW TO KEEP THE TEMPERATURES ON THE CHILLY SIDE. MAX T`S SUNDAY SHOULD ONLY REACH THE MID 40S NORTH TO MID 50S SOUTH. THIS UPPER SYSTEM WILL BE MOISTURE STARVED WITH LITTLE TO NO GULF INFLOW... EXPECT ONLY A CHANCE OF A FEW SPRINKLES. WE WILL ADVERTISE ONLY A SLIGHT CHANCE POP FOR ANYTHING THAT MEASURES 0.01. OTHERWISE... ONLY A FEW TRACE AMOUNTS ARE EXPECTED. THE UPPER LEVEL DISTURBANCE IS FORECAST TO SHIFT EAST SUNDAY EVENING AS WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. HOWEVER... THE FLOW AT THE SURFACE IS EXPECTED TO REMAIN WEAK... INDICATING THAT THERE SHOULD STILL BE SOME RESIDUAL LOW LEVEL MOISTURE AND CLOUDINESS TO DEAL WITH. WE WILL ADVERTISE SKIES TO BECOME PARTLY CLOUDY AS SUBSIDENCE BEHIND THE DEPARTING SHORT WAVE FAVORS CLEARING ALOFT. LOWS SHOULD STILL BE ABOVE CURRENT GUIDANCE AS THE LOW LEVEL MOISTURE SHOULD REMAIN RELATIVE HIGH. EXPECT MOSTLY MID TO UPPER 30S. HEIGHTS ARE FORECAST TO RISE ALOFT MONDAY INTO EARLY TUESDAY AHEAD OF THE NEXT SHORT WAVE TROUGH. THIS WILL BRING MILD TO WARM TEMPERATURES BACK. THE TRENDS IN THE PAST FEW RUNS HAVE BEEN TO SPEED UP THIS TROUGH AND THE ASSOCIATED COLD FRONTAL PASSAGE FOR OUR REGION (NOW APPEARS TO BE DURING THE DAY TUESDAY). THE MAIN SURFACE STORM TRACK WITH THIS TROUGH IS EXPECTED TO BE WEST TO EAST THROUGH THE OHIO VALLEY INTO THE NORTHEAST. THE ONLY SHOT AT SHOWERS FOR CENTRAL NC WILL BE WITH THE TRAILING COLD FRONT EXPECTED TUESDAY. SENSIBLE WEATHER MONDAY LOOKS TO BE DRY AND WARMER WITH HIGHS RETURNING TO THE 60S. INCREASING CLOUDINESS MONDAY NIGHT WITH A SLIGHT CHANCE OF SHOWERS TOWARD DAYBREAK (NW ONLY). LOWS WILL BE MILD WITH THE SW FLOW AND INCREASING CLOUDS (MOSTLY MID TO UPPER 40S). THE SURFACE COLD FRONT SHOULD MOVE THROUGH CENTRAL NC DURING THE DAY TUESDAY. THE BEST CHANCE OF SIGNIFICANT SHOWERS WILL BE OVER THE MOUNTAINS. WITH LIMITED DYNAMICS... AND LITTLE IN THE WAY OF BOUNDARY LAYER INSTABILITY AS THE FRONT MOVES EAST THROUGH CENTRAL NC... WE SHOULD ONLY SEE A BAND OF LIGHT SHOWERS. QPF WILL BE FORECAST AT LESS THAN 0.25 OF AN INCH. HIGHS SHOULD STILL REACH 60-65. STRONG CAA WILL BLOW ACROSS CENTRAL NC BEHIND THE COLD FRONT LATE TUESDAY AND TUESDAY NIGHT. THE SKIES WILL CLEAR RATHER ABRUPTLY AFTER THE FROPA WITH STRONG SUBSIDENCE AND DEEP NW FLOW INDICATED TUESDAY NIGHT. LOWS WILL BE LOWERED INTO THE 25-30 RANGE PER LATEST GUIDANCE. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... A TRANSIENT POSITIVE PNA PATTERN WILL DEVELOP MIDWEEK RESULTING IN A LONGWAVE TROUGH AMPLIFYING OVER THE EASTERN PORTION OF THE COUNTRY. THIS WILL BRING A RETURN OF BELOW NORMAL TEMPERATURES BY WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE PREVIOUS NIGHT`S FRONTAL PASSAGE. HIGHS WEDNESDAY SHOULD ONLY MAKE IT INTO THE UPPER 40S NORTH TO LOWER 50S SOUTH... AND WILL STRUGGLE TO MAKE IT OUT OF THE MID AND UPPER 40S ON THURSDAY. LOWS WED/THU NIGHT WILL DIP INTO THE 20S ACROSS MOST OF THE CWA. AN ALBERTA CLIPPER LOOKS POISED TO APPROACH FROM THE NORTHWEST ON FRIDAY... SENDING ANOTHER WEAK FRONT THROUGH THE AREA FRIDAY NIGHT. AS A WEAK SOUTHWEST FLOW DEVELOPS AHEAD OF THE FRONT... TEMPS ARE APT TO MODERATE SOME DURING THE DAY ON FRIDAY. HIGHS SHOULD REBOUND CLOSER TO NORMAL LEVELS IN THE LOW TO MID 50S. NO PRECIP IS EXPECTED AHEAD OF THIS FRONT GIVEN THE DRY NW FLOW REGIME. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 640 AM SATURDAY... LIFR/IFR CONDITIONS WILL CONTINUE THROUGH THE EARLY MORNING BENEATH A STRONG INVERSION THAT WILL REMAIN AROUND 2K TO 3K FEET THROUGH MOST OF THE MORNING. ALTHOUGH A BIT TOO HIGH FOR LLWS...AIRCRAFT SHOULD NOTE THAT WINDS NEAR THE INVERSION WILL REACH AROUND 35KT FROM THE SOUTHWEST THROUGH 15Z WHILE SFC WINDS REMAIN LIGHT AND VARIABLE. GRADUAL IMPROVEMENT IN CONDITIONS WILL TAKE PLACE TODAY WITH VISIBILITIES EXPECTED TO BECOME VFR SATURDAY MORNING AS THE WESTERLY SURFACE FLOW INCREASES. THE LATEST GUIDANCE HAS DELAYED THE CLEARING OF MVFR/IFR CEILINGS UNTIL LATE THIS AFTERNOON. THIS IS EVEN WITH THE MODELS NOT FULLING CAPTURING THE FULL EXTENT OF LOW LEVEL SATURATION SEEN ON THE 00Z/23 GSO SOUNDING. THEREFORE...HAVE DELAYED VFR CIGS UNTIL LATE AFTERNOON. LOW CEILINGS LIKELY WILL RETURN LATE SATURDAY NIGHT IN AMPLE LOW-LEVEL MOISTURE AND A NORTHEAST SURFACE FLOW THAT DEVELOPS SATURDAY NIGHT OVER CENTRAL NORTH CAROLINA BEHIND A COLD FRONT. MAINLY MID-LEVEL CLOUDS AND SPRINKLES OR PATCHY LIGHT RAIN ARE ANTICIPATED BY SUNDAY AFTERNOON WITH THE PASSAGE OF A MODERATE MID-LEVEL SHORTWAVE. AFTERWARD...THE NEXT...BEST CHANCE FOR MVFR OR EVEN IFR CONDITIONS WILL BE TUESDAY ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE STATE. && .RAH WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ021-022- 038-039-073>075-083>086-088. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...BADGETT LONG TERM...JFB AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
718 AM EST SAT FEB 23 2008 .SYNOPSIS... A WEAK LOW PRESSURE WILL LINGER OVER CENTRAL AND EASTERN NORTH CAROLINA THROUGH MID AFTERNOON... BEFORE MOVING EAST. A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA THIS EVENING... SHIFTING THE WINDS TO THE NORTHEAST. A WEAK SURFACE HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT INTO SUNDAY. AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE STATE FROM THE WEST SUNDAY... BUT IT WILL REMAIN MOISTURE STARVED. && .NEAR TERM /THROUGH TONIGHT/... AS OF 715 AM SATURDAY... SCATTERED THUNDERSTORMS HAVE DEVELOPED OVER THE NORTHERN PIEDMONT AND COASTAL PLAIN. NAM BUFR SOUNDINGS INDICATE A FAIRLY UNSTABLE SOUNDING ABOVE 900 MB. THE RIGHT REAR ENTRANCE OF A 300 MB JET COMBINED DECENT MID LEVEL COOLING ASSOCIATED WITH A 500 MB DISTURBANCE IS PRODUCING ENOUGH LIFT TO REALIZE THE ELEVATED INSTABILITY. SENT A QUICK FORECAST UPDATE TO INCLUDE A CHANCE OF SHOWERS AND THUNDERSTORMS FOR THE NE CWA THROUGH MID MORNING. PREVIOUS DISCUSSION FOLLOWS... THE BACK EDGE OF THE MID AND HIGH LEVEL MOISTURE WAS MOVING EAST OVER THE PIEDMONT. THIS MAY AID IN THE FOG BECOMING MORE DENSE THROUGH DAYBREAK OVER THE WESTERN AND SOUTHERN PIEDMONT... AND POSSIBLY THE SANDHILLS. THEREFORE... WE WILL ISSUE A DENSE FOG ADVISORY FOR AREAS ALONG AND WEST GREENSBORO TO FAYETTEVILLE THROUGH 1000 AM. AS OF 245 AM SATURDAY... THE CURRENT HYBRID COLD AIR DAMMING EPISODE IS EXPECTED TO LINGER WELL INTO THE LATE MORNING HOURS. THE LINGERING LOW STATUS AND FOG WILL BE VERY SLOW TO SCOUR OUT THIS MORNING AS MODELS INDICATE LIGHT WINDS IN THE BOUNDARY LAYER INTO THE LATE MORNING. CURRENT SURFACE OBS INDICTED CEILINGS AND VISIBILITIES WERE REMAINING STATUS QUO... EXCEPT FOR LOWERING SOME OVER DAVIDSON... RANDOLPH... AND STANLY COUNTIES... WHERE WIDESPREAD VSBYS OF 1/2 TO 1 MILE WERE OBSERVED. WE WILL MONITOR THESE AREAS CLOSELY. HOWEVER... THE VISIBILITIES ARE EXPECTED TO REMAIN JUST ABOVE THE THRESHOLD FOR A DENSE FOG ADVISORY. THE 00Z/NAM WAS THE QUICKEST IN BEGINNING THE CLEARING IN THE LEE OF THE APPALACHIANS BY MID TO LATE MORNING... WITH THE GFS INDICATING THE CLEARING WILL BEGIN 3-4 HOURS LATER. GIVEN THE 00Z MODELS LACK OF ABILITY TO INITIALIZE THE SATURATED BOUNDARY LAYER OVER THE PIEDMONT DAMMING REGION...AND THE STRENGTH/DEPTH OF THE CAD (3-5K FEET) BASED ON GSO/RNK 00Z/23 SOUNDINGS... IT APPEARS REASONABLE TO FAVOR THE SLOWER CLEARING INDICATED BY THE 00Z/GFS. THIS CLEARING SHOULD GET GOING IN THE LEE OF THE BLUE RIDGE LATE MORNING AS THE DRY WESTERLY FLOW INCREASES ALOFT WITH THE PASSAGE OF THE MID LEVEL TROUGH. AS THIS TROUGH MOVES EAST THROUGH CENTRAL NC DURING THE AFTERNOON... THE CLEARING WILL SPREAD EAST. THERE SHOULD CONTINUE TO BE SCATTERED TO BROKEN STRATOCUMULUS AT 4-5K FEET EVEN AFTER THE LOWER STRATUS CLEARS OUT. THUS... WE WILL CONTINUE THE CURRENT CLOUDY FORECAST THIS MORNING... BECOMING PARTLY CLOUDY THIS AFTERNOON. THE TEMPERATURES WILL BE HIGHLY DEPENDENT ON HOW MUCH SUN DEVELOPS THIS AFTERNOON. THE PREVIOUS FORECAST (WHICH LOWERED HIGHS FOR TODAY) APPEARS VERY REASONABLE. WE WILL CONTINUE THE CURRENT MAX T FORECASTS INDICATING MID 50S NORTH CENTRAL TO LOWER 60S SE-S. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 245 AM SATURDAY...IN THE WAKE OF THE COLD FRONTAL PASSAGE THIS EVENING... THE SKIES WILL TEMPORARILY BECOME MOSTLY CLEAR FOR MOST AREAS. THIS WILL BE FOLLOWED BY ANOTHER BOUT OF STRATUS/STRATOCUMULUS LATER TONIGHT INTO SUNDAY. THIS WILL OCCUR AS THE LOW LEVEL NE FLOW PULLS ATLANTIC MOISTURE BACK ACROSS OUR REGION. WHILE MODELS WERE GENERALLY IN AGREEMENT THAT STRATOCUMULUS WILL EVENTUALLY DEVELOP INTO OUR REGION... THE 00Z/GFS WAS MUCH FASTER IN SATURATION THE LOW LEVELS ESPECIALLY IN THE EAST OVERNIGHT... SPREADING WEST BY DAYBREAK. MOSTLY CLEAR OR PARTLY CLOUDY SKIES EARLY TONIGHT WILL BECOME OVERCAST AGAIN OVERNIGHT. WITH THIS INCREASINGLY CLOUDY PATTERN TONIGHT... THE WARMER MET STATISTICAL GUIDANCE WAS PREFERRED OVER THE GFS MOS. LOWS SHOULD REMAIN IN THE UPPER 30S TO LOWER 40S... INSTEAD OF THE COLDER LOWER 30S FORECAST BY THE GFS MOS IN THE PIEDMONT. WITH THE UPPER SHORTWAVE EXPECTED TO MOVE EAST ACROSS THE STATE DURING THE DAY SUNDAY... THE LIFT AND ASSOCIATED CLOUDINESS ALOFT WILL COMBINE WITH THE LOW LEVEL MOIST NE FLOW TO KEEP THE TEMPERATURES ON THE CHILLY SIDE. MAX T`S SUNDAY SHOULD ONLY REACH THE MID 40S NORTH TO MID 50S SOUTH. THIS UPPER SYSTEM WILL BE MOISTURE STARVED WITH LITTLE TO NO GULF INFLOW... EXPECT ONLY A CHANCE OF A FEW SPRINKLES. WE WILL ADVERTISE ONLY A SLIGHT CHANCE POP FOR ANYTHING THAT MEASURES 0.01. OTHERWISE... ONLY A FEW TRACE AMOUNTS ARE EXPECTED. THE UPPER LEVEL DISTURBANCE IS FORECAST TO SHIFT EAST SUNDAY EVENING AS WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. HOWEVER... THE FLOW AT THE SURFACE IS EXPECTED TO REMAIN WEAK... INDICATING THAT THERE SHOULD STILL BE SOME RESIDUAL LOW LEVEL MOISTURE AND CLOUDINESS TO DEAL WITH. WE WILL ADVERTISE SKIES TO BECOME PARTLY CLOUDY AS SUBSIDENCE BEHIND THE DEPARTING SHORT WAVE FAVORS CLEARING ALOFT. LOWS SHOULD STILL BE ABOVE CURRENT GUIDANCE AS THE LOW LEVEL MOISTURE SHOULD REMAIN RELATIVE HIGH. EXPECT MOSTLY MID TO UPPER 30S. HEIGHTS ARE FORECAST TO RISE ALOFT MONDAY INTO EARLY TUESDAY AHEAD OF THE NEXT SHORT WAVE TROUGH. THIS WILL BRING MILD TO WARM TEMPERATURES BACK. THE TRENDS IN THE PAST FEW RUNS HAVE BEEN TO SPEED UP THIS TROUGH AND THE ASSOCIATED COLD FRONTAL PASSAGE FOR OUR REGION (NOW APPEARS TO BE DURING THE DAY TUESDAY). THE MAIN SURFACE STORM TRACK WITH THIS TROUGH IS EXPECTED TO BE WEST TO EAST THROUGH THE OHIO VALLEY INTO THE NORTHEAST. THE ONLY SHOT AT SHOWERS FOR CENTRAL NC WILL BE WITH THE TRAILING COLD FRONT EXPECTED TUESDAY. SENSIBLE WEATHER MONDAY LOOKS TO BE DRY AND WARMER WITH HIGHS RETURNING TO THE 60S. INCREASING CLOUDINESS MONDAY NIGHT WITH A SLIGHT CHANCE OF SHOWERS TOWARD DAYBREAK (NW ONLY). LOWS WILL BE MILD WITH THE SW FLOW AND INCREASING CLOUDS (MOSTLY MID TO UPPER 40S). THE SURFACE COLD FRONT SHOULD MOVE THROUGH CENTRAL NC DURING THE DAY TUESDAY. THE BEST CHANCE OF SIGNIFICANT SHOWERS WILL BE OVER THE MOUNTAINS. WITH LIMITED DYNAMICS... AND LITTLE IN THE WAY OF BOUNDARY LAYER INSTABILITY AS THE FRONT MOVES EAST THROUGH CENTRAL NC... WE SHOULD ONLY SEE A BAND OF LIGHT SHOWERS. QPF WILL BE FORECAST AT LESS THAN 0.25 OF AN INCH. HIGHS SHOULD STILL REACH 60-65. STRONG CAA WILL BLOW ACROSS CENTRAL NC BEHIND THE COLD FRONT LATE TUESDAY AND TUESDAY NIGHT. THE SKIES WILL CLEAR RATHER ABRUPTLY AFTER THE FROPA WITH STRONG SUBSIDENCE AND DEEP NW FLOW INDICATED TUESDAY NIGHT. LOWS WILL BE LOWERED INTO THE 25-30 RANGE PER LATEST GUIDANCE. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... A TRANSIENT POSITIVE PNA PATTERN WILL DEVELOP MIDWEEK RESULTING IN A LONGWAVE TROUGH AMPLIFYING OVER THE EASTERN PORTION OF THE COUNTRY. THIS WILL BRING A RETURN OF BELOW NORMAL TEMPERATURES BY WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE PREVIOUS NIGHT`S FRONTAL PASSAGE. HIGHS WEDNESDAY SHOULD ONLY MAKE IT INTO THE UPPER 40S NORTH TO LOWER 50S SOUTH... AND WILL STRUGGLE TO MAKE IT OUT OF THE MID AND UPPER 40S ON THURSDAY. LOWS WED/THU NIGHT WILL DIP INTO THE 20S ACROSS MOST OF THE CWA. AN ALBERTA CLIPPER LOOKS POISED TO APPROACH FROM THE NORTHWEST ON FRIDAY... SENDING ANOTHER WEAK FRONT THROUGH THE AREA FRIDAY NIGHT. AS A WEAK SOUTHWEST FLOW DEVELOPS AHEAD OF THE FRONT... TEMPS ARE APT TO MODERATE SOME DURING THE DAY ON FRIDAY. HIGHS SHOULD REBOUND CLOSER TO NORMAL LEVELS IN THE LOW TO MID 50S. NO PRECIP IS EXPECTED AHEAD OF THIS FRONT GIVEN THE DRY NW FLOW REGIME. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 640 AM SATURDAY... LIFR/IFR CONDITIONS WILL CONTINUE THROUGH THE EARLY MORNING BENEATH A STRONG INVERSION THAT WILL REMAIN AROUND 2K TO 3K FEET THROUGH MOST OF THE MORNING. ALTHOUGH A BIT TOO HIGH FOR LLWS...AIRCRAFT SHOULD NOTE THAT WINDS NEAR THE INVERSION WILL REACH AROUND 35KT FROM THE SOUTHWEST THROUGH 15Z WHILE SFC WINDS REMAIN LIGHT AND VARIABLE. GRADUAL IMPROVEMENT IN CONDITIONS WILL TAKE PLACE TODAY WITH VISIBILITIES EXPECTED TO BECOME VFR SATURDAY MORNING AS THE WESTERLY SURFACE FLOW INCREASES. THE LATEST GUIDANCE HAS DELAYED THE CLEARING OF MVFR/IFR CEILINGS UNTIL LATE THIS AFTERNOON. THIS IS EVEN WITH THE MODELS NOT FULLING CAPTURING THE FULL EXTENT OF LOW LEVEL SATURATION SEEN ON THE 00Z/23 GSO SOUNDING. THEREFORE...HAVE DELAYED VFR CIGS UNTIL LATE AFTERNOON. LOW CEILINGS LIKELY WILL RETURN LATE SATURDAY NIGHT IN AMPLE LOW-LEVEL MOISTURE AND A NORTHEAST SURFACE FLOW THAT DEVELOPS SATURDAY NIGHT OVER CENTRAL NORTH CAROLINA BEHIND A COLD FRONT. MAINLY MID-LEVEL CLOUDS AND SPRINKLES OR PATCHY LIGHT RAIN ARE ANTICIPATED BY SUNDAY AFTERNOON WITH THE PASSAGE OF A MODERATE MID-LEVEL SHORTWAVE. AFTERWARD...THE NEXT...BEST CHANCE FOR MVFR OR EVEN IFR CONDITIONS WILL BE TUESDAY ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE STATE. && .RAH WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ021-022- 038-039-073>075-083>086-088. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT/JFB SHORT TERM...BADGETT LONG TERM...JFB AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
644 AM EST SAT FEB 23 2008 .SYNOPSIS... A WEAK LOW PRESSURE WILL LINGER OVER CENTRAL AND EASTERN NORTH CAROLINA THROUGH MID AFTERNOON... BEFORE MOVING EAST. A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA THIS EVENING... SHIFTING THE WINDS TO THE NORTHEAST. A WEAK SURFACE HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT INTO SUNDAY. AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE STATE FROM THE WEST SUNDAY... BUT IT WILL REMAIN MOISTURE STARVED. && .NEAR TERM /THROUGH TONIGHT/... ...AS OF 530 AM... THE BACK EDGE OF THE MID AND HIGH LEVEL MOISTURE WAS MOVING EAST OVER THE PIEDMONT. THIS MAY AID IN THE FOG BECOMING MORE DENSE THROUGH DAYBREAK OVER THE WESTERN AND SOUTHERN PIEDMONT... AND POSSIBLY THE SANDHILLS. THEREFORE... WE WILL ISSUE A DENSE FOG ADVISORY FOR AREAS ALONG AND WEST GREENSBORO TO FAYETTEVILLE THROUGH 1000 AM. PREVIOUS DISCUSSION... AS OF 245 AM... ...CONSIDERING A DENSE FOG ADVISORY FOR PORTIONS OF THE WESTERN PIEDMONT... MAINLY SW OF THE PIEDMONT TRIAD REGION MORNING... OTHERWISE SLOW CLEARING OF LOW STRATUS AND FOG EXPECTED LATE MORNING INTO THE EARLY AFTERNOON... ...RADAR TRENDS INDICATE NOTHING MORE THAN SPRINKLES FOR OUR SE COUNTIES THROUGH DAYBREAK... AS OF 245 AM SATURDAY... THE CURRENT HYBRID COLD AIR DAMMING EPISODE IS EXPECTED TO LINGER WELL INTO THE LATE MORNING HOURS. THE LINGERING LOW STATUS AND FOG WILL BE VERY SLOW TO SCOUR OUT THIS MORNING AS MODELS INDICATE LIGHT WINDS IN THE BOUNDARY LAYER INTO THE LATE MORNING. CURRENT SURFACE OBS INDICTED CEILINGS AND VISIBILITIES WERE REMAINING STATUS QUO... EXCEPT FOR LOWERING SOME OVER DAVIDSON... RANDOLPH... AND STANLY COUNTIES... WHERE WIDESPREAD VSBYS OF 1/2 TO 1 MILE WERE OBSERVED. WE WILL MONITOR THESE AREAS CLOSELY. HOWEVER... THE VISIBILITIES ARE EXPECTED TO REMAIN JUST ABOVE THE THRESHOLD FOR A DENSE FOG ADVISORY. THE 00Z/NAM WAS THE QUICKEST IN BEGINNING THE CLEARING IN THE LEE OF THE APPALACHIANS BY MID TO LATE MORNING... WITH THE GFS INDICATING THE CLEARING WILL BEGIN 3-4 HOURS LATER. GIVEN THE 00Z MODELS LACK OF ABILITY TO INITIALIZE THE SATURATED BOUNDARY LAYER OVER THE PIEDMONT DAMMING REGION...AND THE STRENGTH/DEPTH OF THE CAD (3-5K FEET) BASED ON GSO/RNK 00Z/23 SOUNDINGS... IT APPEARS REASONABLE TO FAVOR THE SLOWER CLEARING INDICATED BY THE 00Z/GFS. THIS CLEARING SHOULD GET GOING IN THE LEE OF THE BLUE RIDGE LATE MORNING AS THE DRY WESTERLY FLOW INCREASES ALOFT WITH THE PASSAGE OF THE MID LEVEL TROUGH. AS THIS TROUGH MOVES EAST THROUGH CENTRAL NC DURING THE AFTERNOON... THE CLEARING WILL SPREAD EAST. THERE SHOULD CONTINUE TO BE SCATTERED TO BROKEN STRATOCUMULUS AT 4-5K FEET EVEN AFTER THE LOWER STRATUS CLEARS OUT. THUS... WE WILL CONTINUE THE CURRENT CLOUDY FORECAST THIS MORNING... BECOMING PARTLY CLOUDY THIS AFTERNOON. THE TEMPERATURES WILL BE HIGHLY DEPENDENT ON HOW MUCH SUN DEVELOPS THIS AFTERNOON. THE PREVIOUS FORECAST (WHICH LOWERED HIGHS FOR TODAY) APPEARS VERY REASONABLE. WE WILL CONTINUE THE CURRENT MAX T FORECASTS INDICATING MID 50S NORTH CENTRAL TO LOWER 60S SE-S. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 245 AM SATURDAY...IN THE WAKE OF THE COLD FRONTAL PASSAGE THIS EVENING... THE SKIES WILL TEMPORARILY BECOME MOSTLY CLEAR FOR MOST AREAS. THIS WILL BE FOLLOWED BY ANOTHER BOUT OF STRATUS/STRATOCUMULUS LATER TONIGHT INTO SUNDAY. THIS WILL OCCUR AS THE LOW LEVEL NE FLOW PULLS ATLANTIC MOISTURE BACK ACROSS OUR REGION. WHILE MODELS WERE GENERALLY IN AGREEMENT THAT STRATOCUMULUS WILL EVENTUALLY DEVELOP INTO OUR REGION... THE 00Z/GFS WAS MUCH FASTER IN SATURATION THE LOW LEVELS ESPECIALLY IN THE EAST OVERNIGHT... SPREADING WEST BY DAYBREAK. MOSTLY CLEAR OR PARTLY CLOUDY SKIES EARLY TONIGHT WILL BECOME OVERCAST AGAIN OVERNIGHT. WITH THIS INCREASINGLY CLOUDY PATTERN TONIGHT... THE WARMER MET STATISTICAL GUIDANCE WAS PREFERRED OVER THE GFS MOS. LOWS SHOULD REMAIN IN THE UPPER 30S TO LOWER 40S... INSTEAD OF THE COLDER LOWER 30S FORECAST BY THE GFS MOS IN THE PIEDMONT. WITH THE UPPER SHORTWAVE EXPECTED TO MOVE EAST ACROSS THE STATE DURING THE DAY SUNDAY... THE LIFT AND ASSOCIATED CLOUDINESS ALOFT WILL COMBINE WITH THE LOW LEVEL MOIST NE FLOW TO KEEP THE TEMPERATURES ON THE CHILLY SIDE. MAX T`S SUNDAY SHOULD ONLY REACH THE MID 40S NORTH TO MID 50S SOUTH. THIS UPPER SYSTEM WILL BE MOISTURE STARVED WITH LITTLE TO NO GULF INFLOW... EXPECT ONLY A CHANCE OF A FEW SPRINKLES. WE WILL ADVERTISE ONLY A SLIGHT CHANCE POP FOR ANYTHING THAT MEASURES 0.01. OTHERWISE... ONLY A FEW TRACE AMOUNTS ARE EXPECTED. THE UPPER LEVEL DISTURBANCE IS FORECAST TO SHIFT EAST SUNDAY EVENING AS WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. HOWEVER... THE FLOW AT THE SURFACE IS EXPECTED TO REMAIN WEAK... INDICATING THAT THERE SHOULD STILL BE SOME RESIDUAL LOW LEVEL MOISTURE AND CLOUDINESS TO DEAL WITH. WE WILL ADVERTISE SKIES TO BECOME PARTLY CLOUDY AS SUBSIDENCE BEHIND THE DEPARTING SHORT WAVE FAVORS CLEARING ALOFT. LOWS SHOULD STILL BE ABOVE CURRENT GUIDANCE AS THE LOW LEVEL MOISTURE SHOULD REMAIN RELATIVE HIGH. EXPECT MOSTLY MID TO UPPER 30S. HEIGHTS ARE FORECAST TO RISE ALOFT MONDAY INTO EARLY TUESDAY AHEAD OF THE NEXT SHORT WAVE TROUGH. THIS WILL BRING MILD TO WARM TEMPERATURES BACK. THE TRENDS IN THE PAST FEW RUNS HAVE BEEN TO SPEED UP THIS TROUGH AND THE ASSOCIATED COLD FRONTAL PASSAGE FOR OUR REGION (NOW APPEARS TO BE DURING THE DAY TUESDAY). THE MAIN SURFACE STORM TRACK WITH THIS TROUGH IS EXPECTED TO BE WEST TO EAST THROUGH THE OHIO VALLEY INTO THE NORTHEAST. THE ONLY SHOT AT SHOWERS FOR CENTRAL NC WILL BE WITH THE TRAILING COLD FRONT EXPECTED TUESDAY. SENSIBLE WEATHER MONDAY LOOKS TO BE DRY AND WARMER WITH HIGHS RETURNING TO THE 60S. INCREASING CLOUDINESS MONDAY NIGHT WITH A SLIGHT CHANCE OF SHOWERS TOWARD DAYBREAK (NW ONLY). LOWS WILL BE MILD WITH THE SW FLOW AND INCREASING CLOUDS (MOSTLY MID TO UPPER 40S). THE SURFACE COLD FRONT SHOULD MOVE THROUGH CENTRAL NC DURING THE DAY TUESDAY. THE BEST CHANCE OF SIGNIFICANT SHOWERS WILL BE OVER THE MOUNTAINS. WITH LIMITED DYNAMICS... AND LITTLE IN THE WAY OF BOUNDARY LAYER INSTABILITY AS THE FRONT MOVES EAST THROUGH CENTRAL NC... WE SHOULD ONLY SEE A BAND OF LIGHT SHOWERS. QPF WILL BE FORECAST AT LESS THAN 0.25 OF AN INCH. HIGHS SHOULD STILL REACH 60-65. STRONG CAA WILL BLOW ACROSS CENTRAL NC BEHIND THE COLD FRONT LATE TUESDAY AND TUESDAY NIGHT. THE SKIES WILL CLEAR RATHER ABRUPTLY AFTER THE FROPA WITH STRONG SUBSIDENCE AND DEEP NW FLOW INDICATED TUESDAY NIGHT. LOWS WILL BE LOWERED INTO THE 25-30 RANGE PER LATEST GUIDANCE. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... A TRANSIENT POSITIVE PNA PATTERN WILL DEVELOP MIDWEEK RESULTING IN A LONGWAVE TROUGH AMPLIFYING OVER THE EASTERN PORTION OF THE COUNTRY. THIS WILL BRING A RETURN OF BELOW NORMAL TEMPERATURES BY WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE PREVIOUS NIGHT`S FRONTAL PASSAGE. HIGHS WEDNESDAY SHOULD ONLY MAKE IT INTO THE UPPER 40S NORTH TO LOWER 50S SOUTH... AND WILL STRUGGLE TO MAKE IT OUT OF THE MID AND UPPER 40S ON THURSDAY. LOWS WED/THU NIGHT WILL DIP INTO THE 20S ACROSS MOST OF THE CWA. AN ALBERTA CLIPPER LOOKS POISED TO APPROACH FROM THE NORTHWEST ON FRIDAY... SENDING ANOTHER WEAK FRONT THROUGH THE AREA FRIDAY NIGHT. AS A WEAK SOUTHWEST FLOW DEVELOPS AHEAD OF THE FRONT... TEMPS ARE APT TO MODERATE SOME DURING THE DAY ON FRIDAY. HIGHS SHOULD REBOUND CLOSER TO NORMAL LEVELS IN THE LOW TO MID 50S. NO PRECIP IS EXPECTED AHEAD OF THIS FRONT GIVEN THE DRY NW FLOW REGIME. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 640 AM SATURDAY... LIFR/IFR CONDITIONS WILL CONTINUE THROUGH THE EARLY MORNING BENEATH A STRONG INVERSION THAT WILL REMAIN AROUND 2K TO 3K FEET THROUGH MOST OF THE MORNING. ALTHOUGH A BIT TOO HIGH FOR LLWS...AIRCRAFT SHOULD NOTE THAT WINDS NEAR THE INVERSION WILL REACH AROUND 35KT FROM THE SOUTHWEST THROUGH 15Z WHILE SFC WINDS REMAIN LIGHT AND VARIABLE. GRADUAL IMPROVEMENT IN CONDITIONS WILL TAKE PLACE TODAY WITH VISIBILITIES EXPECTED TO BECOME VFR SATURDAY MORNING AS THE WESTERLY SURFACE FLOW INCREASES. THE LATEST GUIDANCE HAS DELAYED THE CLEARING OF MVFR/IFR CEILINGS UNTIL LATE THIS AFTERNOON. THIS IS EVEN WITH THE MODELS NOT FULLING CAPTURING THE FULL EXTENT OF LOW LEVEL SATURATION SEEN ON THE 00Z/23 GSO SOUNDING. THEREFORE...HAVE DELAYED VFR CIGS UNTIL LATE AFTERNOON. LOW CEILINGS LIKELY WILL RETURN LATE SATURDAY NIGHT IN AMPLE LOW-LEVEL MOISTURE AND A NORTHEAST SURFACE FLOW THAT DEVELOPS SATURDAY NIGHT OVER CENTRAL NORTH CAROLINA BEHIND A COLD FRONT. MAINLY MID-LEVEL CLOUDS AND SPRINKLES OR PATCHY LIGHT RAIN ARE ANTICIPATED BY SUNDAY AFTERNOON WITH THE PASSAGE OF A MODERATE MID-LEVEL SHORTWAVE. AFTERWARD...THE NEXT...BEST CHANCE FOR MVFR OR EVEN IFR CONDITIONS WILL BE TUESDAY ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE STATE. && .RAH WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ021-022- 038-039-073>075-083>086-088. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT/JFB SHORT TERM...BADGETT LONG TERM...JFB AVIATION...JFB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
530 AM EST SAT FEB 23 2008 .SYNOPSIS... A WEAK LOW PRESSURE WILL LINGER OVER CENTRAL AND EASTERN NORTH CAROLINA THROUGH MID AFTERNOON... BEFORE MOVING EAST. A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA THIS EVENING... SHIFTING THE WINDS TO THE NORTHEAST. A WEAK SURFACE HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT INTO SUNDAY. AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE STATE FROM THE WEST SUNDAY... BUT IT WILL REMAIN MOISTURE STARVED. && .NEAR TERM /THROUGH TONIGHT/... ...AS OF 530 AM... THE BACK EDGE OF THE MID AND HIGH LEVEL MOISTURE WAS MOVING EAST OVER THE PIEDMONT. THIS MAY AID IN THE FOG BECOMING MORE DENSE THROUGH DAYBREAK OVER THE WESTERN AND SOUTHERN PIEDMONT... AND POSSIBLY THE SANDHILLS. THEREFORE... WE WILL ISSUE A DENSE FOG ADVISORY FOR AREAS ALONG AND WEST GREENSBORO TO FAYETTEVILLE THROUGH 1000 AM. PREVIOUS DISCUSSION... AS OF 245 AM... ...CONSIDERING A DENSE FOG ADVISORY FOR PORTIONS OF THE WESTERN PIEDMONT... MAINLY SW OF THE PIEDMONT TRIAD REGION MORNING... OTHERWISE SLOW CLEARING OF LOW STRATUS AND FOG EXPECTED LATE MORNING INTO THE EARLY AFTERNOON... ...RADAR TRENDS INDICATE NOTHING MORE THAN SPRINKLES FOR OUR SE COUNTIES THROUGH DAYBREAK... AS OF 245 AM SATURDAY... THE CURRENT HYBRID COLD AIR DAMMING EPISODE IS EXPECTED TO LINGER WELL INTO THE LATE MORNING HOURS. THE LINGERING LOW STATUS AND FOG WILL BE VERY SLOW TO SCOUR OUT THIS MORNING AS MODELS INDICATE LIGHT WINDS IN THE BOUNDARY LAYER INTO THE LATE MORNING. CURRENT SURFACE OBS INDICTED CEILINGS AND VISIBILITIES WERE REMAINING STATUS QUO... EXCEPT FOR LOWERING SOME OVER DAVIDSON... RANDOLPH... AND STANLY COUNTIES... WHERE WIDESPREAD VSBYS OF 1/2 TO 1 MILE WERE OBSERVED. WE WILL MONITOR THESE AREAS CLOSELY. HOWEVER... THE VISIBILITIES ARE EXPECTED TO REMAIN JUST ABOVE THE THRESHOLD FOR A DENSE FOG ADVISORY. THE 00Z/NAM WAS THE QUICKEST IN BEGINNING THE CLEARING IN THE LEE OF THE APPALACHIANS BY MID TO LATE MORNING... WITH THE GFS INDICATING THE CLEARING WILL BEGIN 3-4 HOURS LATER. GIVEN THE 00Z MODELS LACK OF ABILITY TO INITIALIZE THE SATURATED BOUNDARY LAYER OVER THE PIEDMONT DAMMING REGION...AND THE STRENGTH/DEPTH OF THE CAD (3-5K FEET) BASED ON GSO/RNK 00Z/23 SOUNDINGS... IT APPEARS REASONABLE TO FAVOR THE SLOWER CLEARING INDICATED BY THE 00Z/GFS. THIS CLEARING SHOULD GET GOING IN THE LEE OF THE BLUE RIDGE LATE MORNING AS THE DRY WESTERLY FLOW INCREASES ALOFT WITH THE PASSAGE OF THE MID LEVEL TROUGH. AS THIS TROUGH MOVES EAST THROUGH CENTRAL NC DURING THE AFTERNOON... THE CLEARING WILL SPREAD EAST. THERE SHOULD CONTINUE TO BE SCATTERED TO BROKEN STRATOCUMULUS AT 4-5K FEET EVEN AFTER THE LOWER STRATUS CLEARS OUT. THUS... WE WILL CONTINUE THE CURRENT CLOUDY FORECAST THIS MORNING... BECOMING PARTLY CLOUDY THIS AFTERNOON. THE TEMPERATURES WILL BE HIGHLY DEPENDENT ON HOW MUCH SUN DEVELOPS THIS AFTERNOON. THE PREVIOUS FORECAST (WHICH LOWERED HIGHS FOR TODAY) APPEARS VERY REASONABLE. WE WILL CONTINUE THE CURRENT MAX T FORECASTS INDICATING MID 50S NORTH CENTRAL TO LOWER 60S SE-S. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 245 AM SATURDAY...IN THE WAKE OF THE COLD FRONTAL PASSAGE THIS EVENING... THE SKIES WILL TEMPORARILY BECOME MOSTLY CLEAR FOR MOST AREAS. THIS WILL BE FOLLOWED BY ANOTHER BOUT OF STRATUS/STRATOCUMULUS LATER TONIGHT INTO SUNDAY. THIS WILL OCCUR AS THE LOW LEVEL NE FLOW PULLS ATLANTIC MOISTURE BACK ACROSS OUR REGION. WHILE MODELS WERE GENERALLY IN AGREEMENT THAT STRATOCUMULUS WILL EVENTUALLY DEVELOP INTO OUR REGION... THE 00Z/GFS WAS MUCH FASTER IN SATURATION THE LOW LEVELS ESPECIALLY IN THE EAST OVERNIGHT... SPREADING WEST BY DAYBREAK. MOSTLY CLEAR OR PARTLY CLOUDY SKIES EARLY TONIGHT WILL BECOME OVERCAST AGAIN OVERNIGHT. WITH THIS INCREASINGLY CLOUDY PATTERN TONIGHT... THE WARMER MET STATISTICAL GUIDANCE WAS PREFERRED OVER THE GFS MOS. LOWS SHOULD REMAIN IN THE UPPER 30S TO LOWER 40S... INSTEAD OF THE COLDER LOWER 30S FORECAST BY THE GFS MOS IN THE PIEDMONT. WITH THE UPPER SHORTWAVE EXPECTED TO MOVE EAST ACROSS THE STATE DURING THE DAY SUNDAY... THE LIFT AND ASSOCIATED CLOUDINESS ALOFT WILL COMBINE WITH THE LOW LEVEL MOIST NE FLOW TO KEEP THE TEMPERATURES ON THE CHILLY SIDE. MAX T`S SUNDAY SHOULD ONLY REACH THE MID 40S NORTH TO MID 50S SOUTH. THIS UPPER SYSTEM WILL BE MOISTURE STARVED WITH LITTLE TO NO GULF INFLOW... EXPECT ONLY A CHANCE OF A FEW SPRINKLES. WE WILL ADVERTISE ONLY A SLIGHT CHANCE POP FOR ANYTHING THAT MEASURES 0.01. OTHERWISE... ONLY A FEW TRACE AMOUNTS ARE EXPECTED. THE UPPER LEVEL DISTURBANCE IS FORECAST TO SHIFT EAST SUNDAY EVENING AS WEAK HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. HOWEVER... THE FLOW AT THE SURFACE IS EXPECTED TO REMAIN WEAK... INDICATING THAT THERE SHOULD STILL BE SOME RESIDUAL LOW LEVEL MOISTURE AND CLOUDINESS TO DEAL WITH. WE WILL ADVERTISE SKIES TO BECOME PARTLY CLOUDY AS SUBSIDENCE BEHIND THE DEPARTING SHORT WAVE FAVORS CLEARING ALOFT. LOWS SHOULD STILL BE ABOVE CURRENT GUIDANCE AS THE LOW LEVEL MOISTURE SHOULD REMAIN RELATIVE HIGH. EXPECT MOSTLY MID TO UPPER 30S. HEIGHTS ARE FORECAST TO RISE ALOFT MONDAY INTO EARLY TUESDAY AHEAD OF THE NEXT SHORT WAVE TROUGH. THIS WILL BRING MILD TO WARM TEMPERATURES BACK. THE TRENDS IN THE PAST FEW RUNS HAVE BEEN TO SPEED UP THIS TROUGH AND THE ASSOCIATED COLD FRONTAL PASSAGE FOR OUR REGION (NOW APPEARS TO BE DURING THE DAY TUESDAY). THE MAIN SURFACE STORM TRACK WITH THIS TROUGH IS EXPECTED TO BE WEST TO EAST THROUGH THE OHIO VALLEY INTO THE NORTHEAST. THE ONLY SHOT AT SHOWERS FOR CENTRAL NC WILL BE WITH THE TRAILING COLD FRONT EXPECTED TUESDAY. SENSIBLE WEATHER MONDAY LOOKS TO BE DRY AND WARMER WITH HIGHS RETURNING TO THE 60S. INCREASING CLOUDINESS MONDAY NIGHT WITH A SLIGHT CHANCE OF SHOWERS TOWARD DAYBREAK (NW ONLY). LOWS WILL BE MILD WITH THE SW FLOW AND INCREASING CLOUDS (MOSTLY MID TO UPPER 40S). THE SURFACE COLD FRONT SHOULD MOVE THROUGH CENTRAL NC DURING THE DAY TUESDAY. THE BEST CHANCE OF SIGNIFICANT SHOWERS WILL BE OVER THE MOUNTAINS. WITH LIMITED DYNAMICS... AND LITTLE IN THE WAY OF BOUNDARY LAYER INSTABILITY AS THE FRONT MOVES EAST THROUGH CENTRAL NC... WE SHOULD ONLY SEE A BAND OF LIGHT SHOWERS. QPF WILL BE FORECAST AT LESS THAN 0.25 OF AN INCH. HIGHS SHOULD STILL REACH 60-65. STRONG CAA WILL BLOW ACROSS CENTRAL NC BEHIND THE COLD FRONT LATE TUESDAY AND TUESDAY NIGHT. THE SKIES WILL CLEAR RATHER ABRUPTLY AFTER THE FROPA WITH STRONG SUBSIDENCE AND DEEP NW FLOW INDICATED TUESDAY NIGHT. LOWS WILL BE LOWERED INTO THE 25-30 RANGE PER LATEST GUIDANCE. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... A TRANSIENT POSITIVE PNA PATTERN WILL DEVELOP MIDWEEK RESULTING IN A LONGWAVE TROUGH AMPLIFYING OVER THE EASTERN PORTION OF THE COUNTRY. THIS WILL BRING A RETURN OF BELOW NORMAL TEMPERATURES BY WEDNESDAY AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE PREVIOUS NIGHT`S FRONTAL PASSAGE. HIGHS WEDNESDAY SHOULD ONLY MAKE IT INTO THE UPPER 40S NORTH TO LOWER 50S SOUTH... AND WILL STRUGGLE TO MAKE IT OUT OF THE MID AND UPPER 40S ON THURSDAY. LOWS WED/THU NIGHT WILL DIP INTO THE 20S ACROSS MOST OF THE CWA. AN ALBERTA CLIPPER LOOKS POISED TO APPROACH FROM THE NORTHWEST ON FRIDAY... SENDING ANOTHER WEAK FRONT THROUGH THE AREA FRIDAY NIGHT. AS A WEAK SOUTHWEST FLOW DEVELOPS AHEAD OF THE FRONT... TEMPS ARE APT TO MODERATE SOME DURING THE DAY ON FRIDAY. HIGHS SHOULD REBOUND CLOSER TO NORMAL LEVELS IN THE LOW TO MID 50S. NO PRECIP IS EXPECTED AHEAD OF THIS FRONT GIVEN THE DRY NW FLOW REGIME. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 1230 AM SATURDAY...IFR CONDITIONS AND OFTEN LIFR CONDITIONS DUE TO CEILINGS WILL BE IN PLACE OVERNIGHT BENEATH STRONG INVERSION THAT WILL REMAIN AROUND 2K TO 3K FEET AT LEAST THROUGH 12Z. ALTHOUGH A BIT TOO HIGH FOR LLWS...AIRCRAFT SHOULD NOTE THAT WINDS NEAR THE INVERSION...ESPECIALLY TOWARD KFAY...COULD REACH AROUND 35KT FROM THE SOUTHWEST BETWEEN 09Z AND 12Z. GRADUAL IMPROVEMENT IN CONDITIONS WILL TAKE PLACE SATURDAY...WITH VISIBILITIES EXPECTED TO BECOME VFR SATURDAY MORNING AS THE WESTERLY SURFACE FLOW INCREASES... FOLLOWED BY VFR CEILINGS MAINLY IN THE AFTERNOON IN THE DEEP...WESTERLY FLOW AS NOTED ON GFS AND NAM BUFR SOUNDINGS. LOW CEILINGS LIKELY WILL RETURN LATE SATURDAY NIGHT IN AMPLE LOW-LEVEL MOISTURE AND A NORTHEAST SURFACE FLOW THAT DEVELOPS SATURDAY NIGHT OVER CENTRAL NORTH CAROLINA BEHIND A COLD FRONT. MAINLY MID-LEVEL CLOUDS AND SPRINKLES OR PATCHY LIGHT RAIN ARE ANTICIPATED BY SUNDAY AFTERNOON WITH THE PASSAGE OF A MODERATE MID-LEVEL SHORTWAVE. AFTERWARD...THE NEXT...BEST CHANCE FOR MVFR OR EVEN IFR CONDITIONS WILL BE TUESDAY ALONG AND AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE STATE. && .RAH WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ021-022- 038-039-073>075-083>086-088. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT/JFB SHORT TERM...BADGETT LONG TERM...JFB AVIATION...JFB
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
913 AM EST SAT FEB 23 2008 .DISCUSSION... ACARS SOUNDINGS THIS MORNING FROM TRI INDICATE A DEEP SATURDATED LAYER FROM THE SURFACE TO NEARLY 700 MB. 12Z OHX SOUNDING SHOWS A STRONG INVERSION AND A SATURATED LAYER FROM AROUND 900 TO 800 MB. SURFACE TEMPS TO OUR WEST ARE ALSO 10-15 DEGREES COOLER THAN CURRENT TEMPS IN THE VALLEY. THIS INDICATES THAT THE SURFACE FRONT IS CURRENTLY MOVING THROUGH THE AREA...AND THAT TEMPERATURES WILL NOT RISE MUCH TODAY. A STRENGTHENING INVERSION WILL REDUCE THE POTENTIAL FOR MIXING OUT OF CLOUDS...AND WTIH LIGHT WINDS SHIFTING TO A MORE NORTHERLY COMPONENT...DOWNSLOPE FLOW OFF THE PLATEAU WILL LIKELY NOT HELP TO ERODE THE LOW CLOUDS. THE UPDATE THIS MORNING WILL INCREASE CLOUD COVER AND LOWER MAX TEMPERATURES...AS GFS MOS APPEARS TO BE BREAKING OUT THE CLOUDS TOO QUICKLY. THE DENSE FOG ADVISORY FOR SW NC WILL BE ALLOWED TO EXPIRE AT 10 AM. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DGS
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1007 AM CST SAT FEB 23 2008 .DISCUSSION... SUB 1K FT EARLY MORNING STRATUS DECK BEGINNING TO ERODE ACROSS OUR CENTRAL COUNTIES AT THE END OF THE 16Z HOUR. ACARS AND LCH SOUNDING DATA PAINT A CLEAR PICTURE OF STRONG 950-900MB CAPPING WITH SIGNIFICANT DRY AIR RIGHT OFF THE SURFACE. THIS DRY AIR WILL MIX OUT THE REMAINDER OF THIS DECK QUITE NICELY THROUGH 17Z AS SUNSHINE MAKES IT TO THE SURFACE. EXTRAPOLATING DOWN A DRY ADIABAT FROM TOP OF INVERSION PRODUCES A SFC TEMP IN THE MID 70S. TAKING THIS INTO CONSIDERATION...AND THE OFFSETTING FACT OF A SLOW START TO WARMING PER THIS EARLY AM DECK...MAKES KEEPING MAX TEMPS IN THE LOW 70S THE MOST LOGICAL CHOICE. MISSISSIPPI VALLEY SURFACE HIGH EXPANDING SOUTHWARD OVER EAST TEXAS THIS MORNING WILL CONTINUE UPON ITS EASTWARD TREK...TRANSLATING TO MORE OF A SOUTHEASTERLY WIND BY MID-AFTERNOON. STILL EXPECTING A VERY WEAK AND DRY BOUNDARY TO MAKE IT INTO THE NORTHERN COUNTIES THIS TIME TOMORROW...PRIMARY A SUBTLE NORTHERLY WIND SHIFTER. 31 && .PREV DISCUSSION... /ISSUED 328 AM CST SAT FEB 23 2008/ DISCUSSION... STRATUS DECK HAS PUSHED BACK WEST INTO THE FAR ERN ZONES EARLY THIS MORNING. THE CLOUD COVER WILL LINGER FOR A FEW HOURS. WESTERLY FLOW IN THE 850 MB LAYER WHICH SHOULD ALLOW THESE CLOUDS TO MIX OUT BY MID-LATE MORNING. OTHERWISE...LOOKS LIKE A GREAT DAY WITH PLENTY OF SUNSHINE AND LIGHT WINDS. HAVE LOWERED MAX TEMPS A FEW DEGREES GIVEN THE VERY COOL START THIS MORNING. SFC RIDGE WILL MOVE EAST OF THE AREA ALLOWING ONSHORE WINDS TO RETURN THIS AFTN. CLEAR SKIES...LIGHT WINDS...AND GRADUAL RETURN OF LOW LEVEL MOISTURE WILL FAVOR RADIATIONAL FOG DEVELOPMENT ACROSS MUCH OF THE AREA LATE TONIGHT/EARLY SUNDAY. HAVE PLACED DENSE FOG OVER THE COASTAL/SW ZONES WHERE CONFIDENCE IS HIGHEST. SUNDAY`S WEATHER IS LOOKING GREAT AS WELL. THE WEAK COLD FRONT IS NOW FORECAST TO STALL OVER OUR NRN ZONES AND HAVE LITTLE EFFECT ON OUR WEATHER. HAVE BUMPED UP MAX TEMPS INTO THE UPPER 70S/NEAR 80 FOR INLAND AREAS. SFC DEWPOINTS FORECAST TO REACH THE MID 60S ALONG THE COAST BY SUNDAY EVENING. LOOKS LIKE SEA FOG WILL BEGIN DEVELOPING OVER THE BAYS/NEARSHORE WATERS SUNDAY EVENING...ADVECTING INLAND AS FOG OR A VERY LOW STRATUS DECK. FOG SHOULD BURN OFF MID MORNING MONDAY FOLLOWED BY PARTLY CLOUDY SKIES AND INCREASING SOUTHERLY WINDS AS LOW PRESSURE DEEPENS OVER THE PLAINS. 850 MB TEMPS FORECAST TO INCREASE TO AROUND 20C MON AFTN...AND HAVE BUMPED TEMPS UPWARD. LONGWAVE TROUGH CARVES OUT OVER MS VALLEY LATE MONDAY PUSHING A STRONG COLD FRONT THROUGH SE TX MONDAY NIGHT. GFS BUFR SOUNDINGS SHOW FAIRLY IMPRESSIVE SHEAR/INSTABILITY OVER OUR NRN ZONES BEGINNING LATE MONDAY. HAVE INTRODUCED SOME LOW POPS FOR NE ZONES BEGINNING MON AFTN. THE STRONG CAPPING AT 850 MB LEVEL WILL BE A MAJOR LIMITING FACTOR IN CONVECTIVE DEVELOPMENT. THINK FORCING WILL EVENTUALLY OVERCOME CAPPING AND ALLOW A THIN BAND OF SHRA/TSRA TO DEVELOP ALONG/JUST BEHIND FRONT AS IT CROSSES THE AREA. FRONT SHOULD PUSH OFF THE COAST BY 12Z TUESDAY. MID LEVEL CLOUDINESS WILL LINGER FOR A FEW HOURS WITH CLEARING...COOLER... BREEZY CONDITIONS TUE AFTN. WED MORNING LOOKS LIKE THE COLDEST MORNING. IF THE WINDS DIE DOWN ENOUGH THEN WE COULD SEE A LIGHT FREEZE IN SOME RURAL NORTHERN AREAS. ONSHORE FLOW RETURNS WED NIGHT/THURSDAY RESULTING IN A GRADUAL WARMUP AND SOME LOW CLOUDINESS SPREADING INTO THE AREA. GFS/ECMWF DIFFER AT THE END OF THE WEEK...WITH GFS MORE AGGRESSIVE WITH MOISTURE RETURN/PRECIP POTENTIAL. HAVE GONE WITH MOSTLY CLOUDY SKIES BUT KEPT POPS LOW. 35 && MARINE... NORTHEAST FLOW ACROSS WATERS BECOMING EASTERLY AS THE DAY PROGRESSES. HIGH PRESSURE RIDGE SHIFTING EAST OF REGION. THIS WILL RESULT IN THE FLOW BECOMING MORE SOUTHEAST BY TONIGHT. THIS FLOW WILL STRENGTHEN LATER MONDAY DUE TO TIGHTENING PRESSURE GRADIENT. WAVE HEIGHTS WILL INCREASE LATE MONDAY ESPECIALLY OFFSHORE REGION. IF GFS IS CORRECT UPPER TEXAS COASTAL WATERS SHOULD SEE SCA FLAG LATE MONDAY. A STRONG COLD FRONT WILL MOVE ACROSS THE REGION LATE MONDAY NIGHT AND EARLY TUESDAY MORNING. THIS FRONT WILL USHER A VIGOROUS OFFSHORE FLOW PROBABLY 20-30 KTS TUESDAY. 37 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 71 53 79 58 83 / 0 0 0 0 10 HOUSTON (IAH) 70 53 79 58 82 / 0 0 0 0 10 GALVESTON (GLS) 65 59 72 62 74 / 0 0 0 0 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...31