AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
AFDPHI 245 PM EST MON JAN 22 2007
.OVERVIEW...
WINTER IS HERE AND WILL HANG AROUND FOR AWHILE.
.SHORT TERM/TONIGHT THROUGH WEDNESDAY NIGHT/...
PLENTY OF DANK AND DREARY LOOKING CLOUDS AROUND THE REGION WHICH
WILL STAY AROUND FOR A COUPLE OF DAYS. NOT MUCH IN THE WAY OF WIND
BUT WHEN TEMPERATURES ARE IN THE 20S, DOESN`T TAKE MUCH TO COOL YOU
DOWN EVEN MORE. SO WHEN IS THE NEXT TIME FOR PRECIPITATION? THE
NORTHERN BRANCH WILL PREVAIL OVER A GOOD PART OF THE WORKWEEK. SOME
OF THE COLDEST TEMPERATURES WILL BE WEDNESDAY INTO THURSDAY WITH A
-18C AT 80H. JUST UP THE ROAD A SHORT DISTANCE A -26C IS OVER NEW
YORK STATE. THE LOW THAT BROUGHT SNOW TO US ON SUNDAY IS OFF THE
COAST AND PULLING DOWN SOME COLD AIR, BUT ITS THE NEXT SHORT WAVE
OVER JAMES BAY THAT IS GOING TO PUSH SOUTHEAST AND BRING THE
REINFORCED COLD. ANY PRECIPITATION LIKELY TO BE IN THE FORM OF
LIGHT SNOW OR A PASSING SNOW SHOWER AND THAT COULD OCCUR AT ANY TIME
WITH NO ORGANIZED DYNAMICS TO SET ANYTHING OFF EXCEPT OFF THE
GREAT LAKES. SO WE`LL CONTINUE TO A NORTHWEST FLOW COLD TEMPERATURES AND
MOSTLY CLOUDY SKIES INTO WEDNESDAY NIGHT. MEANWHILE, CLOSED LOW OVER
OLD MEXICO WILL REMAIN ANCHORED TO THE SOUTHERN IN THE TAIL END OF
THE SOUTHERN BRANCH.
.LONG TERM/THURSDAY THROUGH MONDAY/...
WE CONTINUE IN THE SAME PATTERN FOR THE EXTENDED PERIOD AND IT IS
EVEN COLDER THAN THE SHORT TERM. A NICE PIPE LINE OF REINFORCED COLD
AIR SETS UP FROM EDMONTON DOWN THROUGH THE MID ATLANTIC COAST.
ALTHOUGH COLD, THIS PATTERN WILL NOT SUPPORT THE DEVELOPMENT OF A
MAJOR STORM. THE COLDEST DAY THIS WEEK LOOKS LIKE FRIDAY WITH THE
NEXT SHOT OF COLD AIR. ABOUT THE THE ONLY THING WE CAN HOPE FOR IN
THE WAY OF SNOW IS A CLIPPER OR TWO TO DROP ABOUT 4 TO 5 INCHES IN A
FELLED SWOOP OVER OUR SOUTHERN ZONES. OUR EXTENDED PERIOD FOR 27 JAN
THROUGH FEB 4 IS FOR BELOW NORMAL TEMPERATURES AND NEAR NORMAL
PRECIPITATION. WHAT THIS PATTERN DOES DO IN THE LONG TERM IS SET THE
STAGE, WITH THE COLD AIR IN PLACE, FOR A LOW TO DEVELOP OVER THE
NORTHERN GULF AND THEN TRACK UP THROUGH THE APPALACHIANS WITH
SECONDARY DEVELOPMENT OVER THE CAROLINAS. BUT THAT IS NOT IN THE
FORESEEABLE FUTURE OF THE MODELS. JUST ENJOY THE SEASONABLE COLD,
STAY WARM AND FOR THOSE HOPING FOR SNOW, IT WILL HAPPEN.
&&
.AVIATION...
THE MAJORITY OF THE TERMINALS HAVE BEEN STUCK IN THE IFR TO MVFR
RANGE, HOWEVER SOME IMPROVEMENT HAS TAKEN PLACE EARLY THIS AFTERNOON
AS SOMEWHAT DRIER AIR IS WORKING ITS WAY DOWN. SOME PILOT REPORTS
THOUGH INDICATE MODERATE TO SEVERE ICING IN THE KABE VICINITY AT
6,000-8,000 FEET. EARLIER ACARS DATA AT PHILADELPHIA SHOWED A FAIRLY
SHALLOW LAYER OF SATURATION AND THE 12Z LWX RAOB INDICATED THE
MOISTURE WAS MOSTLY BELOW 5,000 FEET. VISIBLE SATELLITE IMAGERY AND
SURFACE OBS SHOW A WEALTH OF CLOUDS ACROSS THE MID ATLANTIC.
HOWEVER, SOME BREAKS DEVELOPED IN NORTHERN VIRGINIA. THE MAIN
FORECAST CHALLENGE IS THE EXTENT OF ANY LOW-LEVEL DRYING TONIGHT
INTO TUESDAY. FORECAST SOUNDINGS INDICATE NOT MUCH MIXING WITHIN THE
LOWER PORTION OF THE BOUNDARY LAYER DESPITE AN INCREASING PRESSURE
GRADIENT. IT APPEARS THE EXTENT OF THE MOIST LAYER HAS DECREASED
THIS AFTERNOON WITH SEVERAL AREAS SEEING CEILINGS COME UP. ORGINALLY
THOUGHT MOISTURE WOULD HANG TOUGH, WHICH IT HAS BUT CEILINGS ARE NOW
RESPONDING IN THE UPSWING DIRECTION AT MANY LOCATIONS. NOT VERY
CONFIDENT THAT THIS WILL HOLD OVERNIGHT, THEREFORE DID NOT WANT TO
BE TOO OPTIMISTIC. GENERALLY HELD ONTO IFR TO MVFR CONDITIONS
OVERNIGHT AS THERE IS A SHORT WAVE THAT IS FORECAST TO CRUISE ACROSS
THE AREA TONIGHT, KEEPING CLOUDS IN PLACE. AREAS THAT SEE CEILINGS
LIFTING SOME THIS AFTERNOON, MAY TEND TO LOWER AGAIN TONIGHT WITH
THE LOW-LEVEL MOISTURE IN PLACE. THERE IS AN INCREASING PRESSURE
GRADIENT OVERNIGHT, HOWEVER SURFACE WINDS MAY NOT RESPOND MUCH. WE
IMPROVED THINGS THOUGH TUESDAY MORNING AS BETTER MIXING SHOULD ALLOW
SOME DRYING TO TAKE PLACE. THERE COULD BE A FEW SNOW SHOWERS TONIGHT
IN THE KABE AND KRDG VICINITY, WITH SOME FLURRIES POSSIBLY DOWN TO A
KTTN-KILG LINE AS THE SHORT WAVE MOVES THROUGH. HOWEVER DID NOT
CARRY ANY LIGHT PRECIPITATION IN THE 18Z TAFS.
&&
.MARINE...
CONDITIONS RATHER TRANQUIL ACROSS THE AREA WATERS TODAY WITH SEAS 2
FEET OR LESS OVER THE COASTAL WATERS AND ABOUT A FOOT ON DELAWARE
BAY. WINDS HAVE BEEN ABOUT 10 KNOTS OR LESS SO FAR. LOW PRESSURE
WELL OFF THE NORTH CAROLINA COAST THIS AFTERNOON WILL CONTINUE TO
MOVE NORTHEASTWARD TONIGHT WELL EAST OF OUR AREA. HOWEVER AS THIS
SYSTEM MOVES TO OUR EAST THEN NORTHEAST, THE PRESSURE GRADIENT WILL
TIGHTEN UP SOME OVERNIGHT AND DURING THE DAY ON TUESDAY. BUFKIT
SOUNDINGS INDICATE GUSTS UP TO 25 KNOTS ARE POSSIBLE STARTING LATE
TONIGHT AND CONTINUING INTO TUESDAY EVENING. FOR NOW WE WILL ALLOW
FOR GUSTS TO APPROACH 25 KNOTS AND HOLD OFF ON A SMALL CRAFT
ADVISORY. SOME WEAK SURFACE RIDGING MOVES IN TUESDAY EVENING, WHICH
SHOULD DIMINISH THE WINDS A BIT. A STRONG COLD FRONT IS FORECAST TO
APPROACH THE WATERS WEDNESDAY, THEN SWEEP ACROSS EARLY WEDNESDAY
EVENING. STRONG CAA COUPLED WITH A TIGHTENING PRESSURE GRADIENT AS
LOW PRESSURE DEEPENS NEAR NOVA SCOTIA WILL PRODUCE GUSTY WINDS OVER
THE MARINE AREA. BUFKIT PROFILES INDICATE 30-KNOT GUSTS POSSIBLE
WEDNESDAY NIGHT AND THURSDAY. AS THE CORE OF THE COLD AIR DROPS
DOWN THURSDAY NIGHT AND FRIDAY, PLENTY OF WIND ALOFT COUPLED WITH
COLD AIR POURING OVER THE RELATIVELY MILD WATER COULD PRODUCE GALE
FORCE GUSTS. FOR THURSDAY NIGHT AND FRIDAY WAVEWATCH INDICATING 7
FOOT SEAS AT BUOY 44009. WITH THE FLOW EXPECTED TO BE OFFSHORE, WE
WILL TOP THE SEAS AT ABOUT 5-6 FEET.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
J...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
OVERVIEW/SHORT/LONG TERM...EBERWINE
AVIATION/MARINE...GORSE
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 245 PM EST MON JAN 22 2007
.SHORT TERM (TONIGHT-TUESDAY)...
EXTENSIVE LOW CLOUDS OVER THE ENTIRE OHIO VALLEY REGION TODAY. THIS
COUPLED WITH WEAK COLD ADVECTION HAS LED TO STEADY OR SLOWLY FALLING
TEMPS TODAY...IN THE MID-UPPER 30S MOST PLACES AS OF 19Z. SCT PRECIP
ON RADAR...AND BASED ON SPOTTER REPORTS COUPLED WITH ACARS DATA...
PTYPE IS A MIX OF -RA/-SN/-PL...BUT INTENSITIES ARE VERY LIGHT.
EXPECT THIS TO CONTINUE FOR THE REMAINDER OF THE AFTN HOURS.
FCST SOUNDINGS SHOW LOW LEVEL LAPSE RATES STEEPENING INTO THE
EVENING HOURS. THIS ALONG WITH LIFT FROM PASSING UPPER TROF WILL
HELP CONTINUE POTENTIAL FOR PRECIP THIS EVENING...WILL WORD AS
SLIGHT CHANCE OF -SHRA/-SHSN...HOWEVER AIRMASS ABOVE 800MB (ICE
CRYSTAL LEVELS) IS FCST TO REMAIN ON THE DRY SIDE...SO PRECIP AMTS
SHOULD BE LIGHT AND WE MAY END UP SEEING MORE OF A PATCHY LIGHT
DRIZZLE/FLURRY TYPE DEAL. WILL MENTION ISLTD SLICK SPOTS POSSIBLE IN
THE HWO FOR TONIGHT AND EARLY TUESDAY MORNING.
CHANCES FOR PRECIP SHOULD DIMINISH AFTER 6Z AS UPPER WAVE PASSES OFF
TO THE EAST...BUT SKIES WILL REMAIN CLOUDY PER NAM/GFS FCST
SOUNDINGS. BOTH SHOW CLOUD COVER DIMINISHING TUESDAY AS DRIER AIR
ADVECTS IN FROM THE W/SW...WHICH IS OBSERVED IN VISIBLE SATELLITE
OVER AR/OK ATTM. HOWEVER THAT MAY BE DELAYED DUE TO VERY STRONG
INVERSION SEEN AROUND 850MB. OVERALL WILL TREND TOWARD PARTLY CLOUDY
WORDING IN THE AFTN TUESDAY.
REGARDING TEMPS...USED A 50/50 BLEND OF NAM/GFS TEMPS WHICH YIELDED
MIDDLE 20S MOST LOCATIONS FOR LOWS TONIGHT...AND UPPER 30S/LOWER 40S
FOR HIGHS TUESDAY.
CS
.LONG TERM (TUESDAY NIGHT-MONDAY)...
TUES NIGHT-WED NIGHT...
THIS PERIOD BEGINS WITH THE UPPER FLOW PATTERN MAINLY ZONAL/SLIGHTLY
NW. AT THE SFC...LOW PRESSURE AND ASSOCIATED FRONT EXTEND FROM
HUDSON BAY SW TO SRN GREAT LAKES. A SHORTWAVE EMBEDDED IN WNW FLOW
ALOFT IS LOCATED ACROSS THE NRN PLAINS. AT THIS TIME...THINK THE SFC
FRONT FROM THE GREAT LAKES MAY STAY TO OUR NE FOR THE MOST
PART...AND ONLY BRING A SLIGHT WIND SHIFT TO THE AREA WED MORNING.
HOWEVER TIME-HEIGHT CROSS SECTIONS ACROSS OUR NE FROM THE NAM AND
GFS INDICATE DEEPER MOISTURE FROM 06-12Z...EXTENDING INTO THE -5 TO
-15 DEGREE C RANGE. THINK THAT ONLY TRACE AMOUNTS OF PRECIP WOULD
OCCUR (IN THE FORM OF FLURRIES) SO MAY INSERT THIS INTO THE GRIDS.
THINK A BETTER CHANCE RESIDES WITH THE UPPER PLAINS` SHORTWAVE
DIVING SEWD ACROSS THE CWA WED NIGHT. THIS MAY HELP SPARK A FEW
LIGHT SHOWERS ACROSS THE AREA...WITH THE BEST CHANCE ACROSS THE NERN
CWA. THINK SLT CHC SNOW SHOWERS SHOULD DO THE TRICK. ANY PRECIP
WOULD BE LIGHT IN NATURE.
THU-FRI...
THIS PERIOD WILL BE MAINLY DRY AS UPPER TROUGH MOVES OFF TO THE NE
AND SFC HIGH PRESSURE TRIES TO NOSE IN FROM THE WEST. STILL A NW
FLOW ALOFT WILL BE PRESENT ACROSS THE REGION...AND MAY HAVE SOME
LINGERING FLURRIES ACROSS OUR NE THU MORN. WOULD BE A MINIMAL SHOT
SO WILL NOT INSERT INTO GRIDS AT THIS TIME. MODELS HAVE BEEN
TRENDING CLOSER TO THE ECMWF...WHICH HAS BEEN THE MOST CONSISTENT
MODEL DOWNPLAYING THE SOUTHWARD ADVANCEMENT OF ARCTIC AIR.
STILL...THINK TEMPS WILL HAVE A HARD TIME GETTING OUT OF THE 30S FOR
THU UNDER THE NW FLOW (ESPECIALLY ACROSS OUR NE). TEMPS SHOULD
SLOWLY MODERATE ON FRI...WITH VALUES CLOSER TO NORMAL.
SAT-MON...
THIS PERIOD POSES THE MOST UNCERTAINTY...HOWEVER FORECASTER
CONFIDENCE INCREASING DUE TO THE CONSISTENCY WITH THE ECMWF. AT THE
BEGINNING OF THIS PERIOD...UPPER FLOW ALOFT IS STILL A WNW
FLOW...WITH A CUT-OFF LOW OVER THE SWRN CONUS FINALLY EJECTING INTO
THE SRN PLAINS. MODERATING TEMPS CONTINUE WITH SWRLY SFC WINDS AND
SLT RIDGING OVERHEAD. A SFC LOW IS LOCATED OVER THE GREAT LAKES
REGION SAT MORN...WITH SWWD EXTENDING FRONT. THIS FRONT WILL LIKELY
PASS THROUGH THE REGION SATURDAY...WHILE AT THE SAME TIME UPPER LOW
EJECTING INTO PLAINS TRAVELS JUST TO OUR SOUTH. A COMBINATION OF
THESE POSES A SLT PRECIP THREAT FOR THE AREA...HOWEVER QPF AMOUNTS
LOOK VERY LIGHT AT THIS POINT SINCE OUR CWA RESIDES IN THE MIDDLE OF
THE TWO NRN AND SRN STREAMS. WILL JUST CARRY SLT CHC POPS...AND
WOULD LIKELY START OFF AS LIQUID. SAT NIGHT...PRECIP SHOULD SWITCH
TO -SHSN AS TEMPS AT 850MB DROP TO AROUND -12 DEGREES C. UPPER
TROUGH BEHIND NRN STREAM FRONT TRIES TO BRING ARCTIC AIR INTO THE
REGION...HOWEVER TREND IS TO LIGHTEN THE PUNCH...WITH THE NE CONUS
REALLY EXPERIENCING THE WORST OF THE ARCTIC AIR. COULD HAVE A CHC OF
FLURRIES WITH THE UPPER TROUGH PASSAGE...BUT GIVEN VERY DRY ATMS
WILL NOT INSERT INTO THE GRIDS FOR SUNDAY AT THIS TIME. DESPITE THE
MODELS TRENDING TOWARD KEEPING THE COLDEST TEMPS TO OUR
NE...ENSEMBLES STILL SHOW TEMPS 1 STD DEV BELOW NORM SUN-MON...SO
WILL TREND TOWARD ROUGHLY 3-5 DEGREES BELOW NORMAL FOR THESE DAYS.
AL
&&
.AVIATION (18Z TAFS)...
EXTENSIVE LOW STRATUS WILL BE THE DOMINANT FORECAST PROBLEM FOR
AVIATION CONCERNS THE NEXT 24 HRS.
BASED ON OBSERVATIONAL TRENDS AND LATEST RUC/NAM SOUNDINGS...
EXPECT SCT AREAS OF DRIZZLE/-SHRA TO CONTINUE THROUGH THE AFTN
HOURS. THESE WILL LOCALLY REDUCE CIGS/VSBYS TO AROUND 700FT/1SM
RESPECTIVELY. OTHERWISE CIGS WILL REMAIN IN THE MVFR CATEGORY
THROUGH 0Z...WITH VSBYS IN THE VFR RANGE. WILL MAINTAIN 6SM -DZ
BR AS PREVAILING AT SDF/LEX/BWG.
INTO THIS EVENING LOWER LEVELS COOL SUCH THAT A FEW FLURRIES OR
-SHSN MAY BE POSSIBLE HOWEVER COVERAGE IS NOT ENOUGH TO INCLUDE IN
THE TAFS AT THIS TIME. LOW LEVEL RH FIELDS SUGGEST THAT CIGS MAY
LIFT SLIGHTLY FROM LATE AFTN INTO THE EVENING AS DRIER AIR SLIDES
ACROSS THE CWA...BUT ONLY TEMPORARILY. NAM FCST SOUNDINGS THEN
INDICATE THAT CIGS MAY BECOME QUITE LOW (LIFR) AFTER 6Z
(ESPECIALLY AT LEX) WHILE MOS GUIDANCE IS LESS PESSIMISTIC. WILL
GO WITH A BLEND OF SOLUTIONS FOR THE TIME BEING.
WITH HIGH PRES MOVING INTO THE REGION FROM THE PLAINS...WINDS WILL
GENERALLY BE WESTERLY AND LIGHT...AOB 10KTS THROUGH THE 18Z TAF
PERIOD.
CS
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 1217 PM EST MON JAN 22 2007
.AVIATION (18Z TAFS)...
EXTENSIVE LOW STRATUS WILL BE THE DOMINANT FORECAST PROBLEM FOR
AVIATION CONCERNS THE NEXT 24 HRS.
BASED ON OBSERVATIONAL TRENDS AND LATEST RUC/NAM SOUNDINGS...
EXPECT SCT AREAS OF DRIZZLE/-SHRA TO CONTINUE THROUGH THE AFTN
HOURS. THESE WILL LOCALLY REDUCE CIGS/VSBYS TO AROUND 700FT/1SM
RESPECTIVELY. OTHERWISE CIGS WILL REMAIN IN THE MVFR CATEGORY
THROUGH 0Z...WITH VSBYS IN THE VFR RANGE. WILL MAINTAIN 6SM -DZ
BR AS PREVAILING AT SDF/LEX/BWG.
INTO THIS EVENING LOWER LEVELS COOL SUCH THAT A FEW FLURRIES OR
-SHSN MAY BE POSSIBLE HOWEVER COVERAGE IS NOT ENOUGH TO INCLUDE IN
THE TAFS AT THIS TIME. LOW LEVEL RH FIELDS SUGGEST THAT CIGS MAY
LIFT SLIGHTLY FROM LATE AFTN INTO THE EVENING AS DRIER AIR SLIDES
ACROSS THE CWA...BUT ONLY TEMPORARILY. NAM FCST SOUNDINGS THEN
INDICATE THAT CIGS MAY BECOME QUITE LOW (LIFR) AFTER 6Z
(ESPECIALLY AT LEX) WHILE MOS GUIDANCE IS LESS PESSIMISTIC. WILL
GO WITH A BLEND OF SOLUTIONS FOR THE TIME BEING.
WITH HIGH PRES MOVING INTO THE REGION FROM THE PLAINS...WINDS WILL
GENERALLY BE WESTERLY AND LIGHT...AOB 10KTS THROUGH THE 18Z TAF
PERIOD.
CS
&&
.PREV DISCUSSION... /ISSUED 1036 AM EST MON JAN 22 2007/
UPDATE...
AREAS OF DRIZZLE OR -SHRA ARE CONTINUING OVER THE LMK CWA THIS
MORNING BASED ON LOCAL RADARS. ACARS SOUNDINGS AND LATEST RUC
INDICATE THAT PTYPE SHOULD REMAIN LIQUID TODAY...WITH ATMOS ABOVE
800MB/-7C REMAINING DRY. WILL INCLUDE AREAS OF DRIZZLE WITH A
SLIGHT CHANCE OF RAIN SHOWERS GIVEN COVERAGE OF PRECIP ON RADAR
CURRENTLY AND VSBYS NEAR 1SM AT FTK. IT`S CONCEIVABLE THAT WITHIN
SPOTS OF HIGHER REFLECTIVITY/DEEPER SATURATION...THERE COULD BE A
BRIEF RA/SN SHOWER...SOMETHING TO WATCH TODAY.
INCOMING 12Z NAM IS SHOWING STEEP LOW LEVEL LAPSE RATES CONTINUING
INTO THE EVENING HOURS...SO HAVE EXTENDED DRIZZLE/SHRA INTO THE
EVENING ACROSS THE CWA. MAY SEE A TRANSITION TO FLURRIES AS LOW
LEVELS COOL. TEMPS TODAY WILL BE A CHALLENGE. EXTENSIVE CLOUD
COVER AND WEAK COLD ADVECTION SHOULD KEEP READINGS NEARLY STEADY.
UPDATED FCST WILL BE OUT BY 11 AM EST.
CS
PREV DISCUSSION... /ISSUED 844 AM EST MON JAN 22 2007/
UPDATE...
QUICK UPDATE TO ACCOUNT FOR PRECIP DEVELOPING FROM NEAR SDF/FTK
OVER INTO SRN INDIANA AND SOUTH TO NEAR BWG. WILL REFER TO THIS AS
PATCHY DRIZZLE. PTYPE BASED ON LATEST ACARS/RUC SOUNDINGS SHOULD
REMAIN LIQUID (DRIZZLE) AS CRITICAL ICE CRYSTAL LAYER IS DRY. REST
OF FCST UNCHANGED AT THIS TIME.
CS
&&
PREV DISCUSSION... /ISSUED 316 AM EST MON JAN 22 2007/
SHORT TERM (TODAY AND TONIGHT)...
SHORT TERM MODELS SHOW VERY LITTLE DISAGREEMENT THRU THE NEXT 24
HRS...WILL LEAN TOWARDS A BLEND OF THE 21Z SREF AND THE 00Z GFS
FOR THE FORECAST PERIOD. ONLY SIGNIFICANT FORECAST PROBLEM IS
DEALING WITH TEMPS AND CLOUDS.
MODEST POSITIVE TILT TROUGH ACROSS THE WESTERN GREAT LAKES INTO
THE PLAINS...WITH CLOSED LOW ACROSS THE GADSDEN PURCHASE REGION OF
THE DESERT SOUTHWEST AND WEAK SE CONUS RIDGING. SFC HI PRESSURE SITS
JUST TO THE WEST OF THE REGION...PRODUCING WNW WINDS. TROUGH
SHIFTS EAST FROM THE PLAINS INTO THE MS VALLEY BY
AFTERNOON...BRINGING IN SLIGHTLY COLDER AIR ALOFT AT 850
MB...850 TEMPS DROPPING TO AROUND -8C. TROUGH PUSHES ON THROUGH
THE MID OHIO VALLEY DURING THE OVERNIGHT PERIOD...AS SFC RIDGING
NUDGES EAST IN THE REGION WITH SLIGHT 850 MB WARMING TOWARDS -4C
AS THE TROUGH PUSHES EAST BY 12Z TUES.
TIME SERIES OF BWG/LEX/SDF EACH SHOW SIGNIFICANT INVERSION
TRAPPING MOISTURE BELOW 850 MB...WITH SFC TO 850 MB RH AVG AROUND
90-95 PERCENT THROUGH 12Z TUES. ABOVE THE 850 MB LAYER THE ATMS IS
MUCH DRIER AND WARMER WITH RH AROUND 15-20 PERCENT THROUGHOUT MUCH
OF THE COLUMN...AND TEMPS WARMING IN THE WSW FLOW AROUND 750 TO 700 MB
TO 0C. BEFORE COOLING AS THE FLOW WEAKENS OVERNIGHT. SO WILL KEEP THE
CLOUDY SKIES THROUGH THE ENTIRE PERIOD...WEAK LIFT SEEN JUST ABOVE
THE MOISTURE DURING THE AFTERNOON AND WILL HAVE DRIZZLE IN AROUND
NOON THRU 5PM.
THE NGMMOS HAS BEEN VERY INCONSISTENT AND JUMPY THE LAST 3 RUNS SO
WILL DISCOUNT...WILL LEAN TOWARDS A BLEND OF THE MET/MAV MOS THIS
AFTERNOON. EACH OF THE TWO HAS SHOWED A TREND OF ABOUT 1 DEGREE
COOLER FOR THE AFTERNOON HIGHS...EASILY EXPLAINABLE DUE TO THE
CLOUDS CREATING LESS HEATING. WILL GO A DEGREE OR TWO WARMER FOR
OVERNIGHT LOWS THAN USING A STRAIGHT BLEND OF THE TWO ALSO DUE TO
THE CLOUDS.
SCHOTT
LONG-TERM (TUESDAY THROUGH SUNDAY)...
THE LONG TERM PERIOD IS STILL CHARACTERIZED BY THE PERSISTENT MEAN
RIDGE ALONG OR A LITTLE WEST OF THE WEST COAST OF THE US AND WESTERN
CANADA. EARLY IN THE PERIOD ANOTHER CUTOFF LOW DEVELOPS OVER THE
SOUTHWESTERN U.S. INTO NORTHWEST MEXICO THAT COULD IMPACT OUR REGION
OVER THE WEEKEND. AT THE SAME TIME...A STRONG SHORT WAVE MOVING INTO
NORTHWEST CANADA TO THE SOUTHEAST OF AK...BRIEFLY FLATTENS THE
WESTERN CANADA RIDGE AND THEN DIGS SOUTHEAST INTO THE SOUTHERN
HUDSON BAY REGION AND IS FOLLOWED BY A SERIES OF OTHER SHORT WAVES
THAT PROMISE TO KEEP THIS NORTHERN STREAM AS THE CONTROLLING
WEATHER MAKER FOR OUR REGION BEFORE BREAKING DOWN A BIT OVER NEXT
WEEKEND.
DURING THE WEDNESDAY-THURSDAY TIME FRAME THIS FIRST CLIPPER LIKE
SYSTEM BRINGS ANOTHER SURGE OF ARCTIC AIR SOUTHWARD INTO THE REGION.
THIS COULD LEAD TO A PERIOD OF SNOW SHOWERS AND/OR FLURRIES FOR A
TIME DURING THE ABOVE MENTIONED COUPLE OF DAYS. THIS IS MORE OR LESS
IN LINE WITH OUR CURRENT FCST.
OVER THE WEEKEND THE NORTHERN STREAM IS MERGED BY THE REMNANTS OF
THE SOUTHWESTERN CUTOFF AND LEADS TO ANOTHER CHC FOR SOME RAIN OR
SNOW. THIS COULD BE ANOTHER SIMILAR SCENARIO TO THIS PAST WEEKEND.
BOTH THE ECMWF AND GFS SHOW A SIMILAR TREND BUT WITH SOME SIGNIFICANT
TIMING DIFFERENCES...THIS WILL HAVE TO BE WATCHED CLOSELY.
ONLY REAL CHANGES TO THE CURRENT FCSTS WERE SOME MINOR TWEAKS WITH
THE HOURLY AND MAX AND MIN TEMPS FOR BETTER CONSISTENCY WITH THE
SURROUNDING FA`S. --21
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS LOUISVILLE KY
AFDLMK 1036 AM EST MON JAN 22 2007
.UPDATE...
AREAS OF DRIZZLE OR -SHRA ARE CONTINUING OVER THE LMK CWA THIS
MORNING BASED ON LOCAL RADARS. ACARS SOUNDINGS AND LATEST RUC
INDICATE THAT PTYPE SHOULD REMAIN LIQUID TODAY...WITH ATMOS ABOVE
800MB/-7C REMAINING DRY. WILL INCLUDE AREAS OF DRIZZLE WITH A
SLIGHT CHANCE OF RAIN SHOWERS GIVEN COVERAGE OF PRECIP ON RADAR
CURRENTLY AND VSBYS NEAR 1SM AT FTK. IT`S CONCEIVABLE THAT WITHIN
SPOTS OF HIGHER REFLECTIVITY/DEEPER SATURATION...THERE COULD BE A
BRIEF RA/SN SHOWER...SOMETHING TO WATCH TODAY.
INCOMING 12Z NAM IS SHOWING STEEP LOW LEVEL LAPSE RATES CONTINUING
INTO THE EVENING HOURS...SO HAVE EXTENDED DRIZZLE/SHRA INTO THE
EVENING ACROSS THE CWA. MAY SEE A TRANSITION TO FLURRIES AS LOW
LEVELS COOL. TEMPS TODAY WILL BE A CHALLENGE. EXTENSIVE CLOUD
COVER AND WEAK COLD ADVECTION SHOULD KEEP READINGS NEARLY STEADY.
UPDATED FCST WILL BE OUT BY 11 AM EST.
CS
&&
.PREV DISCUSSION... /ISSUED 844 AM EST MON JAN 22 2007/
UPDATE...
QUICK UPDATE TO ACCOUNT FOR PRECIP DEVELOPING FROM NEAR SDF/FTK
OVER INTO SRN INDIANA AND SOUTH TO NEAR BWG. WILL REFER TO THIS AS
PATCHY DRIZZLE. PTYPE BASED ON LATEST ACARS/RUC SOUNDINGS SHOULD
REMAIN LIQUID (DRIZZLE) AS CRITICAL ICE CRYSTAL LAYER IS DRY. REST
OF FCST UNCHANGED AT THIS TIME.
CS
PREV DISCUSSION... /ISSUED 316 AM EST MON JAN 22 2007/
SHORT TERM (TODAY AND TONIGHT)...
SHORT TERM MODELS SHOW VERY LITTLE DISAGREEMENT THRU THE NEXT 24
HRS...WILL LEAN TOWARDS A BLEND OF THE 21Z SREF AND THE 00Z GFS
FOR THE FORECAST PERIOD. ONLY SIGNIFICANT FORECAST PROBLEM IS
DEALING WITH TEMPS AND CLOUDS.
MODEST POSITIVE TILT TROUGH ACROSS THE WESTERN GREAT LAKES INTO
THE PLAINS...WITH CLOSED LOW ACROSS THE GADSDEN PURCHASE REGION OF
THE DESERT SOUTHWEST AND WEAK SE CONUS RIDGING. SFC HI PRESSURE SITS
JUST TO THE WEST OF THE REGION...PRODUCING WNW WINDS. TROUGH
SHIFTS EAST FROM THE PLAINS INTO THE MS VALLEY BY
AFTERNOON...BRINGING IN SLIGHTLY COLDER AIR ALOFT AT 850
MB...850 TEMPS DROPPING TO AROUND -8C. TROUGH PUSHES ON THROUGH
THE MID OHIO VALLEY DURING THE OVERNIGHT PERIOD...AS SFC RIDGING
NUDGES EAST IN THE REGION WITH SLIGHT 850 MB WARMING TOWARDS -4C
AS THE TROUGH PUSHES EAST BY 12Z TUES.
TIME SERIES OF BWG/LEX/SDF EACH SHOW SIGNIFICANT INVERSION
TRAPPING MOISTURE BELOW 850 MB...WITH SFC TO 850 MB RH AVG AROUND
90-95 PERCENT THROUGH 12Z TUES. ABOVE THE 850 MB LAYER THE ATMS IS
MUCH DRIER AND WARMER WITH RH AROUND 15-20 PERCENT THROUGHOUT MUCH
OF THE COLUMN...AND TEMPS WARMING IN THE WSW FLOW AROUND 750 TO 700 MB
TO 0C. BEFORE COOLING AS THE FLOW WEAKENS OVERNIGHT. SO WILL KEEP THE
CLOUDY SKIES THROUGH THE ENTIRE PERIOD...WEAK LIFT SEEN JUST ABOVE
THE MOISTURE DURING THE AFTERNOON AND WILL HAVE DRIZZLE IN AROUND
NOON THRU 5PM.
THE NGMMOS HAS BEEN VERY INCONSISTENT AND JUMPY THE LAST 3 RUNS SO
WILL DISCOUNT...WILL LEAN TOWARDS A BLEND OF THE MET/MAV MOS THIS
AFTERNOON. EACH OF THE TWO HAS SHOWED A TREND OF ABOUT 1 DEGREE
COOLER FOR THE AFTERNOON HIGHS...EASILY EXPLAINABLE DUE TO THE
CLOUDS CREATING LESS HEATING. WILL GO A DEGREE OR TWO WARMER FOR
OVERNIGHT LOWS THAN USING A STRAIGHT BLEND OF THE TWO ALSO DUE TO
THE CLOUDS.
SCHOTT
LONG-TERM (TUESDAY THROUGH SUNDAY)...
THE LONG TERM PERIOD IS STILL CHARACTERIZED BY THE PERSISTENT MEAN
RIDGE ALONG OR A LITTLE WEST OF THE WEST COAST OF THE US AND WESTERN
CANADA. EARLY IN THE PERIOD ANOTHER CUTOFF LOW DEVELOPS OVER THE
SOUTHWESTERN U.S. INTO NORTHWEST MEXICO THAT COULD IMPACT OUR REGION
OVER THE WEEKEND. AT THE SAME TIME...A STRONG SHORT WAVE MOVING INTO
NORTHWEST CANADA TO THE SOUTHEAST OF AK...BRIEFLY FLATTENS THE
WESTERN CANADA RIDGE AND THEN DIGS SOUTHEAST INTO THE SOUTHERN
HUDSON BAY REGION AND IS FOLLOWED BY A SERIES OF OTHER SHORT WAVES
THAT PROMISE TO KEEP THIS NORTHERN STREAM AS THE CONTROLLING
WEATHER MAKER FOR OUR REGION BEFORE BREAKING DOWN A BIT OVER NEXT
WEEKEND.
DURING THE WEDNESDAY-THURSDAY TIME FRAME THIS FIRST CLIPPER LIKE
SYSTEM BRINGS ANOTHER SURGE OF ARCTIC AIR SOUTHWARD INTO THE REGION.
THIS COULD LEAD TO A PERIOD OF SNOW SHOWERS AND/OR FLURRIES FOR A
TIME DURING THE ABOVE MENTIONED COUPLE OF DAYS. THIS IS MORE OR LESS
IN LINE WITH OUR CURRENT FCST.
OVER THE WEEKEND THE NORTHERN STREAM IS MERGED BY THE REMNANTS OF
THE SOUTHWESTERN CUTOFF AND LEADS TO ANOTHER CHC FOR SOME RAIN OR
SNOW. THIS COULD BE ANOTHER SIMILAR SCENARIO TO THIS PAST WEEKEND.
BOTH THE ECMWF AND GFS SHOW A SIMILAR TREND BUT WITH SOME SIGNIFICANT
TIMING DIFFERENCES...THIS WILL HAVE TO BE WATCHED CLOSELY.
ONLY REAL CHANGES TO THE CURRENT FCSTS WERE SOME MINOR TWEAKS WITH
THE HOURLY AND MAX AND MIN TEMPS FOR BETTER CONSISTENCY WITH THE
SURROUNDING FA`S. --21
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS LOUISVILLE KY
AFDLMK 844 AM EST MON JAN 22 2007
.UPDATE...
QUICK UPDATE TO ACCOUNT FOR PRECIP DEVELOPING FROM NEAR SDF/FTK
OVER INTO SRN INDIANA AND SOUTH TO NEAR BWG. WILL REFER TO THIS AS
PATCHY DRIZZLE. PTYPE BASED ON LATEST ACARS/RUC SOUNDINGS SHOULD
REMAIN LIQUID (DRIZZLE) AS CRITICAL ICE CRYSTAL LAYER IS DRY. REST
OF FCST UNCHANGED AT THIS TIME.
CS
&&
.PREV DISCUSSION... /ISSUED 316 AM EST MON JAN 22 2007/
SHORT TERM (TODAY AND TONIGHT)...
SHORT TERM MODELS SHOW VERY LITTLE DISAGREEMENT THRU THE NEXT 24
HRS...WILL LEAN TOWARDS A BLEND OF THE 21Z SREF AND THE 00Z GFS
FOR THE FORECAST PERIOD. ONLY SIGNIFICANT FORECAST PROBLEM IS
DEALING WITH TEMPS AND CLOUDS.
MODEST POSITIVE TILT TROUGH ACROSS THE WESTERN GREAT LAKES INTO
THE PLAINS...WITH CLOSED LOW ACROSS THE GADSDEN PURCHASE REGION OF
THE DESERT SOUTHWEST AND WEAK SE CONUS RIDGING. SFC HI PRESSURE SITS
JUST TO THE WEST OF THE REGION...PRODUCING WNW WINDS. TROUGH
SHIFTS EAST FROM THE PLAINS INTO THE MS VALLEY BY
AFTERNOON...BRINGING IN SLIGHTLY COLDER AIR ALOFT AT 850
MB...850 TEMPS DROPPING TO AROUND -8C. TROUGH PUSHES ON THROUGH
THE MID OHIO VALLEY DURING THE OVERNIGHT PERIOD...AS SFC RIDGING
NUDGES EAST IN THE REGION WITH SLIGHT 850 MB WARMING TOWARDS -4C
AS THE TROUGH PUSHES EAST BY 12Z TUES.
TIME SERIES OF BWG/LEX/SDF EACH SHOW SIGNIFICANT INVERSION
TRAPPING MOISTURE BELOW 850 MB...WITH SFC TO 850 MB RH AVG AROUND
90-95 PERCENT THROUGH 12Z TUES. ABOVE THE 850 MB LAYER THE ATMS IS
MUCH DRIER AND WARMER WITH RH AROUND 15-20 PERCENT THROUGHOUT MUCH
OF THE COLUMN...AND TEMPS WARMING IN THE WSW FLOW AROUND 750 TO 700 MB
TO 0C. BEFORE COOLING AS THE FLOW WEAKENS OVERNIGHT. SO WILL KEEP THE
CLOUDY SKIES THROUGH THE ENTIRE PERIOD...WEAK LIFT SEEN JUST ABOVE
THE MOISTURE DURING THE AFTERNOON AND WILL HAVE DRIZZLE IN AROUND
NOON THRU 5PM.
THE NGMMOS HAS BEEN VERY INCONSISTENT AND JUMPY THE LAST 3 RUNS SO
WILL DISCOUNT...WILL LEAN TOWARDS A BLEND OF THE MET/MAV MOS THIS
AFTERNOON. EACH OF THE TWO HAS SHOWED A TREND OF ABOUT 1 DEGREE
COOLER FOR THE AFTERNOON HIGHS...EASILY EXPLAINABLE DUE TO THE
CLOUDS CREATING LESS HEATING. WILL GO A DEGREE OR TWO WARMER FOR
OVERNIGHT LOWS THAN USING A STRAIGHT BLEND OF THE TWO ALSO DUE TO
THE CLOUDS.
SCHOTT
LONG-TERM (TUESDAY THROUGH SUNDAY)...
THE LONG TERM PERIOD IS STILL CHARACTERIZED BY THE PERSISTENT MEAN
RIDGE ALONG OR A LITTLE WEST OF THE WEST COAST OF THE US AND WESTERN
CANADA. EARLY IN THE PERIOD ANOTHER CUTOFF LOW DEVELOPS OVER THE
SOUTHWESTERN U.S. INTO NORTHWEST MEXICO THAT COULD IMPACT OUR REGION
OVER THE WEEKEND. AT THE SAME TIME...A STRONG SHORT WAVE MOVING INTO
NORTHWEST CANADA TO THE SOUTHEAST OF AK...BRIEFLY FLATTENS THE
WESTERN CANADA RIDGE AND THEN DIGS SOUTHEAST INTO THE SOUTHERN
HUDSON BAY REGION AND IS FOLLOWED BY A SERIES OF OTHER SHORT WAVES
THAT PROMISE TO KEEP THIS NORTHERN STREAM AS THE CONTROLLING
WEATHER MAKER FOR OUR REGION BEFORE BREAKING DOWN A BIT OVER NEXT
WEEKEND.
DURING THE WEDNESDAY-THURSDAY TIME FRAME THIS FIRST CLIPPER LIKE
SYSTEM BRINGS ANOTHER SURGE OF ARCTIC AIR SOUTHWARD INTO THE REGION.
THIS COULD LEAD TO A PERIOD OF SNOW SHOWERS AND/OR FLURRIES FOR A
TIME DURING THE ABOVE MENTIONED COUPLE OF DAYS. THIS IS MORE OR LESS
IN LINE WITH OUR CURRENT FCST.
OVER THE WEEKEND THE NORTHERN STREAM IS MERGED BY THE REMNANTS OF
THE SOUTHWESTERN CUTOFF AND LEADS TO ANOTHER CHC FOR SOME RAIN OR
SNOW. THIS COULD BE ANOTHER SIMILAR SCENARIO TO THIS PAST WEEKEND.
BOTH THE ECMWF AND GFS SHOW A SIMILAR TREND BUT WITH SOME SIGNIFICANT
TIMING DIFFERENCES...THIS WILL HAVE TO BE WATCHED CLOSELY.
ONLY REAL CHANGES TO THE CURRENT FCSTS WERE SOME MINOR TWEAKS WITH
THE HOURLY AND MAX AND MIN TEMPS FOR BETTER CONSISTENCY WITH THE
SURROUNDING FA`S. --21
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
AFDMQT 1020 PM EST TUE JAN 23 2007
.UPDATE...
MAIN FCST ISSUES OVERNIGHT ARE LES AND MIN TEMPS.
DESPITE 850MB TEMPS AROUND -14C OVER WRN LAKE SUPERIOR...VERY LITTLE
OR NO LES IS OCCURRING INTO WRN UPPER MI. IN FACT...THERE IS NOT
MUCH IN THE WAY OF LAKE EFFECT CLOUD COVER. THERE HAS BEEN SOME
INCREASE IN CLOUDS RECENTLY DUE TO DIURNAL COOLING AND SOME INCREASE
IN LOW-LEVEL CONVERGENCE AS LAND BREEZES BEGIN TO STRENGTHEN. MAIN
REASON FOR THE LACK OF LES IS THE VERY DRY AIRMASS UPSTREAM OF WRN
LAKE SUPERIOR. EVENING TAMDAR SOUNDING FROM KDLH SHOWED DWPT
DEPRESSIONS OF AROUND 10C UP TO BASE OF INVERSION AT 900MB (3.2KFT
AGL). SHARP DRYING WAS INDICATED ABOVE THAT LEVEL. OVER ERN LAKE
SUPERIOR...LONGER FETCH AND COOLER AIRMASS ARE SUPPORTING ONGOING
LES. EVENING TAMDAR SOUNDING FROM KSAW SHOWED BASE OF INVERSION AT
860MB (4.5KFT AGL) WHERE TEMP WAS -17C. UPSTREAM...CWPL SOUNDING
SHOWED INVERSION BASE AT 900MB (3KFT AGL). BASED ON PERSISTENCE OF
REFLECTIVITIES IN THE 20-27DBZ RANGE PER KMQT RADAR OVER A SMALL
PART OF WRN ALGER COUNTY THIS EVENING...WOULD NOT BE SURPRISED IF A
FEW SPOTS PICKED UP 2 OR 3 INCHES OF FLUFFY SNOW SINCE SUNSET.
MODELS IN GENERAL INDICATE CONVERGENCE INCREASING OVER SCNTRL LAKE
SUPERIOR OVERNIGHT AS WEAKENING PRES GRADIENT ALLOWS FOR
STRENGTHENING LAND BREEZES TO PUSH FARTHER OUT OVER LAKE
SUPERIOR...ESPECIALLY OVER THE FAR ERN PART OF THE LAKE AS CLEAR
SKIES ALLOW TEMPS TO PLUMMET OVER ONTARIO. 00Z RUC13 AND RUC40 GO SO
FAR AS TO DEVELOP A MESOLOW IN THE VCNTY OF MUNISING IN THE 09-12Z
TIME FRAME. THAT`S NOT TOTALLY OUT OF THE QUESTION...BUT SEEMS LIKE
A LOW PROBABILITY GIVEN STRENGTH OF NNW FLOW OVER ERN LAKE SUPERIOR
AT THIS HR. STILL...IT WILL BE SOMETHING TO WATCH FOR TOWARD
SUNRISE. IN ANYCASE...STRENGTHENING CONVERGENCE SHOULD LEAD TO MORE
CONSOLIDATED BANDS STREAMING INTO ALGER COUNTY...BUT DRY
AIRMASS/LOWERING INVERSION PER CWPL SOUNDING WILL KEEP SNOW
ACCUMULATIONS IN CHECK. WILL PAINT ANOTHER 1-2 INCHES THERE
OVERNIGHT. OVER THE W...WHILE SOME LIGHT LES MAY REDEVELOP DUE TO
CONVERGENCE WITH STRENGTHENING LAND BREEZES...NOT EXPECTING MUCH
MORE THAN A DUSTING DUE TO SHORT FETCH/DRY AIRMASS.
AS FOR TEMPS...READINGS ARE ALREADY NEAR OR BLO FCST OVER THE
INTERIOR SW BASED ON KIWD/KLNL OBS WHICH INDICATED 0F/-4F
RESPECTIVELY AT 03Z. ALTHOUGH LATEST SATELLITE IMAGERY INDICATES
SOME CLOUDS MAY STREAM INTO THE INTERIOR SW FCST AREA OFF LAKE
SUPERIOR...TEMPS WILL PROBABLY STILL DROP TOWARD -10F IN THE USUAL
COLD SPOTS WITH LITTLE IN THE WAY OF CLOUD COVER FOR AT LEAST THE
NEXT FEW HRS. SOME MID/HIGH CLOUDS SHOULD ARRIVE FROM THE NW LATER IN
THE NIGHT TO SLOW TEMP FALL.
&&
.PREV DISCUSSION... ISSUED AT 335 PM EST
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW COLD NW FLOW ACRS
THE UPR GRT LKS BTWN WRN RDG/ERN TROF IN CLASSIC NEGATIVE NAO/
POSITIVE PNA PATTERN. SHRTWV PLUNGING SEWD THRU THIS FLOW NOW MOVING
INTO LK HURON DRAGGED A COLD FNT ACRS THE FA EARLIER IN THE DAY THAT
TRIGGERED NMRS -SHSN NEAR LK SUP. SINCE ANTECEDENT AIRMASS WAS ON
THE DRY SIDE PER 12Z GRB RAOB AND DEEPER MSTR CONFINED WELL TO THE S
WITHIN SRN BRANCH FLOW...LTL SN FELL ACRS THE SCNTRL AWAY FM LK
MOISTENING. VSBL STLT IMAGERY SHOWS MULTIPLE LES BANDS HAVE DVLPD IN
THE NW FLOW OVER LK SUP BTWN LO PRES NEAR JAMES BAY/ARCTIC HI PRES
NR LK WINNIPEG AND FOLLOWING THE FROPA AS COLD AIR (12Z H85 TEMP AT
YPL -20C) FLOWING ACRS THE RELATIVELY WARM LK WATERS (1-3C PER GLERL
ANALYSIS). HOWEVER...DRYNESS OF UPSTREAM AIR AS EVIDENCED BY 12Z
PWAT OF 0.09 INCH AT INL AND 0.05 INCH AT YPL/SFC DWPTS ARND -5F
UPSTREAM/NEARLY CLR SKIES FM THE MN ARROWHEAD-LK NIPIGON-FARTHER NW
ONTARIO AS WELL AS DNVA/SHARP SUBSIDENCE IN THE WAKE OF SHRTWV HAVE
CAUSED RELATIVELY WIDE SPACING BTWN THE BANDS AND CAUSED THE BACK
EDGE OF THE LK CLD TO PUSH STEADILY SEWD... ESPECIALLY OVER WRN LK
SUP. NEXT SHRTWV OF CONCERN NOW MOVING INTO NRN SASKATCHEWAN.
MAIN FCST CONCERNS THE NEXT COUPLE OF DAYS IS TIMING OF SHRTWVS
DROPPING SEWD IN THE NW FLOW ALF AND RELATED LES AMTS/TRENDS.
FOR TNGT...SHRTWV RDGING BTWN DEPARTING SYS AND SHRTWV NOW OVER NRN
SASKATCHEWAN THAT IS FCST TO PUSH INTO NW ONTARIO BY 12Z WED WL
DOMINATE...RESULTING IN INVRN SINKING TO 3-4K FT. LES WL CONTINUE IN
LINGERING LLVL NW FLOW...BUT CONSIDERING THE VERY DRY NATURE OF THE
INCOMING AIRMASS AND WEAKENING CYC FLOW/RELATIVELY WEAK LLVL CNVGC
THRU THE NGT...EXPECT LES AMTS TO BE LESS THAN SUGGESTED BY LES
CHART (UP TO 3-5 INCHES/12 HRS)...ESPECIALLY ACRS THE W WITH SHORTER
FETCH LENGTH. SO NO HEADLINES WL BE NECESSARY. WL HEDGE BLO EVEN THE
LO END OF MOS GUIDANCE FOR MIN TEMPS ESPECIALLY AWAY FM LK
MOISTENING CONSIDERING THE UPSTREAM DRY AIR. GOING FCST TMINS LOOK
RSNBL.
ON WED...SHRTWV FCST TO DIG SHARPLY TO NEAR THE CWA/WI BORDER BY 00Z
THU. FAIRLY STRG DPVA/H85-5 QVECTOR CNVGC FCST TO IMPACT THE FA ON
THE CYC SIDE OF THE H5 VORT TRACK...BUT ISENTROPIC LIFT/MSTR (PWAT
NO MORE THAN 0.20 INCH) WL BE LIMITED. EXPECT NO MORE THAN SCT
-SHSN/FLURRIES ACRS THE SCNTRL...BUT WL ELEVATE POPS TO LIKELY NR LK
SUP CONSIDERING THE EXTRA MOISTENING OFF THE WATER/STRG DYNAMICS ON
CYC SIDE OF SHRTWV PASSAGE. GIVEN THE LACK OF ISENTROPIC LIFT WITH
H85 TEMPS SLOWLY FALLING THRU THE DAY AND EXPECTED CLD COVER...
PREFER THE LO END OF MOS GUIDANCE (GFS MOS) FOR MAX TEMPS.
LOOK FOR LES IN THE NLY FLOW LEFT IN THE WAKE OF SHRTWV THAT IS FCST
TO DIG INTO THE OH VALLEY BY 12Z THU AS ONE OF THE COLDEST AIRMASSES
OF THE SEASON DRIVES INTO THE AREA. 12Z UKMET/ECMWF/NAM SHOW H85
TEMPS FALLING TO -24C OVER THE E TO -20C OVER THE W BY 12Z THU.
ALTHOUGH NAM FCST SDNGS HINT THAT DEEP MSTR WL LINGER THRU THE
NGT... PREFER THE DRIER GFS FCST PROFILES...ESPECIALLY AFT A
REINFORCING SHRTWV/ASSOCIATED DPVA AND H85-5 QVECTOR CNVGC PASS BY
ARND 06Z. ALTHOUGH THE SETUP FOR LES LOOKS IMPRESSIVE...ESPECIALLY
IN THE N WIND FVRD SN BELTS DOWNWIND OF THE LONGER FETCH ACRS ERN LK
SUP WHERE INCOMING DRY AIR WL HAVE MORE OPPORTUNITY TO MOISTEN...
IMPACT OF THIS DRY AIR/VERY LO TEMPS NOT FVRBL FOR OPTIMUM SN
GROWTH/ RELATIVELY WEAK AND TRANSIENT FCST LLVL CNVGC WITH VEERING
LLVL WINDS SUG LES WL NOT BE AS SGNFT AS LES CHART WOULD SUG. BUT
WITH IMPACT OF DPVA ASSOCIATED WITH REINFORCING SHRTWV...LATER
SHIFTS MAY NEED TO CONSIDER NEED FOR LES ADVY IN THE N WIND FVRD SN
BELTS E OF THE HURON MTNS WHERE FCST DYNAMICS APPEAR STRONGER AND
LLVL CNVGC MORE PERSISTENT IN LONGER FETCH. EXPECT LES TO DIMINISH
SLOWLY ON THU AS HGTS RISE SLOWLY W-E IN THE WAKE OF SECONDARY
SHRTWV AND LLVL FLOW BECOMES MORE ACYC. LIKELY POPS SEEM JUSTIFIED
ALL DAY OVER THE E.
PER NCEP PREFERENCE...HAVE FOLLOWED THE SLOWER UKMET/NAM MODELS FOR
THU NGT/FRI PD. 12Z GFS WOULD BRING WAD SN CHCS IN SW FLOW AHEAD OF
INCOMING SHRTWV INTO THE ENTIRE FA BY LATE THU NGT...BUT SLOWER
UKMET/NAM HINT SFC RDG AXIS WL BE SLOWER TO SHIFT TO THE E.
HOWEVER... INTRODUCED LO CHC POPS EARLIER THAN PREVIOUS FCST OVER
WRN LK SUP AS EARLY AS LATE THU NGT AND THEN ACRS THE ENTIRE FA ON
FRI TO ACCOUNT FOR FASTER TREND OF 12Z ECMWF/00Z GFS REFCST ENSEMBLE
MEAN. TENDED TOWARD THE LWR NAM MOS AND/OR GOING FCST LO/HI TEMPS
THU NGT/FRI TO ACCOUNT FOR MORE PERSISTENT LLVL COLD AIR/SLOWER RDG.
IN THE MEDIUM/EXTENDED RANGE...NEGATIVE NAO/POSITIVE PNA PATTERN WL
MAINTAIN ITS ICY GRIP ON ERN NAMERICA WITH NW FLOW ALF BTWN HI
AMPLITUDE RDG OVER WRN NAMERICA AND DEEP TROF OVER THE E ADVECTING
ARCTIC AIR INTO THE AREA. TIMING/IMPACT OF CLIPPER SHRTWVS EMBEDDED
WITHIN THIS FLOW WL BE THE MAIN CHALLENGE IN THIS PD. THE FIRST OF
THESE SHRTWVS WL BE A SGNFT INFLUENCE ON THE WX OVER UPR MI THIS
WEEKEND. OPERATIONAL MODELS SHOW SHRTWV REACHING NRN MANITOBA/FAR NW
ONTARIO BY 00Z SAT AND THEN SPLITING WITH ONE PIECE MOVING TO NEAR
JAMES BAY AND ANOTHER TO NEAR WRN LK SUP BY 00Z SUN. THE ECMWF HAS
BEEN THE MOST CONSISTENT WITH THE DETAILS OF THIS SYS...AND NCEP HAS
CLOSELY FOLLOWED THE 00Z ECMWF FCST. 12Z GFS HAS TRENDED FASTER
AGAIN AFT 06Z RUN HAD SLOWED DOWN FCST ARRIVAL OF THE SYS. AS
MENTIONED ABV...FOLLOWED THE SLOWER 12Z UKMET AND NAM/00Z ECMWF FOR
TIMING OF PCPN ASSOCIATED WITH THIS SYS PER NCEP PREFERENCE. THE 00Z
ECMWF SHOWS A DRY SFC TROF PASSAGE ON FRI NGT (H7 RH BLO 30 PCT) AS
INITIAL SHRTWV/SFC LO MOVES ACRS ONTARIO. DEEPER MSTR EVIDENT ON SAT
AS SECOND SHRTWV DIGS INTO THE UPR GRT LKS. GOING FCST SCHC POPS FOR
FRI NGT TRANSITIONING TO HIER CHC POPS ON SAT ESPECIALLY NR LK SUP
APPEARS ON TRACK. ECMWF AND OTHER OPS MODELS HAVE BACKED OFF ON
EXTENT OF COLD AIR FCST TO DROP INTO THE UPR LKS IN THE WAKE OF THIS
CLIPPER COMPLEX...BUT INCOMING AIRMASS (H85 TEMPS ARND -18C) ARE
STILL LO ENUF TO JUSTIFY LIKELY POPS FOR LES SAT NGT WHEN FA FCST TO
FALL ON CYC SIDE OF H5 VORT TRACK. LOOK FOR THE LES TO WIND DOWN ON
SUN WITH APRCH OF RISING HGTS/SFC HI PRES RDG AXIS IN ADVANCE OF
NEXT CLIPPER SHRTWV THAT WL IMPACT THE FA ON MON. THEN A CHANCE OF
LES IN THE WAKE OF THIS SYS ON TUE.
COORDINATED WITH DLH.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE
&&
$$
ROLFSON (UPDATE)
KC (PREV DISCUSSION)
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
AFDMQT 335 PM EST MON JAN 22 2007
.DISCUSSION...
12Z ROABS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NRN BRANCH NW FLOW
ALF OVER THE UPR GRT LKS BTWN RDG OVER THE NRN ROCKIES/SW CAN AND
GENERAL TROFFING IN SE CAN. DEEPER MSTR CONFINED TO THE SRN CONUS
WITHIN THE SRN BRANCH FLOW THERE. FA CURRENTLY UNDER THE INFLUENCE
OF WEAK SFC-H7 RDG NOSING INTO THE UPR GRT LKS. ALTHOUGH THERE HAVE
BEEN SOME FLURRIES/-SN ARND IN ASSOCIATION WITH DEPARTING WEAK TROF
NOW OVER ERN LK SUP AS WELL AS SOME SFC-H8 MSTR SHOWN ON THE 12Z
APX/GRB RAOBS AND 16Z TAMDAR SDNG FM SAW...WHAT LTL SN THAT IS
FALLING APPEARS TO BE DIMINISHING/ENDING W-E AS DRIER AIR SHOWN ON
THE 12Z INL SDNG PUSHES INTO THE UPR GRT LKS. 12Z PWAT AT INL ONLY
0.16 INCH. NEXT SHRTWV OF CONCERN NOW MOVING INTO CNTRL MANITOBA.
PCPN IN ADVANCE OF THIS FEATURE IS QUITE LIMITED BY DRY AIR SHOWN ON
THE 12Z INL/BIS/YQD SDNGS DESPITE MODEST ISENTROPIC LIFT/PRES FALLS
IN THE SW FLOW AHEAD OF SHRTWV.
MAIN FCST CONCERNS THE NEXT FEW DAYS REVOLVE ARND TIMING/IMPACT OF
UPSTREAM SHRTWV DROPPING INTO THE UPR GRT LKS IN NW FLOW ALF.
FOR TNGT...GOOD AGREEMENT AMONG NAM/GFS/CNDN MODELS SHOWING SHRTWV
NOW OVER MANITOBA REACHING CNTRL UPR MI BY 12Z TUE. GFS SHOWS AREA
OF H85-5 QVECTOR CNVGC/DPVA MOVING INTO THE FA OVERNGT WHILE
ISENTROPIC LIFT APPEARS TO WEAKEN. CONSIDERING DRY AIR UPSTREAM AND
MINIMAL MOS POPS...PREFER THE DRIER LOOK OF THE NAM FCST SDNGS. HAVE
OPTED TO CARRY CHC POPS ONLY ACRS THE NRN TIER ON CYC SIDE OF H5
VORT TRACK WITH JUST FLURRIES ALG THE WI BORDER/SCNTRL. HIEST POP TO
LIKELY OVER THE KEWEENAW...BUT AOB 50 ELSEWHERE. GIVEN OBSVD LO MIN
TEMPS UPSTREAM THIS MRNG AND RELATIVELY DRY AIR...WL TEND TOWARD THE
LOWER ETA/NGM MOS GUIDANCE FOR MIN TEMPS.
EXPECT LES TO DVLP ON TUE DOWNWIND OF LK SUP IN FCST NNW FLOW BEHIND
SHRTWV AS H85 TEMPS AS LO AS -15C TO -17C ADVECT INTO THE NRN TIER
ZNS BY 00Z WED. WL CARRY LIKELY POPS NR LK SUP AND JUST A CHC OF
-SHSN/FLURRIES FARTHER INLAND. INCOMING AIRMASS APPEARS TO BE RATHER
DRY WITH INVRN LWRG TO ARND H85 DURING THE AFTN UNDER H85-5 QVECTOR
DVGC/DNVA/SUBSIDENCE...SO EXPECT SUB ADVY ACCUMULATIONS. EXPECT HI
TEMPS RELATIVELY EARLY IN THE DAY BEFORE INFUSION OF COLDER AIR
CAUSES TEMPS REMAIN NEARLY STEADY IN THE AFTN. LES MODERATED BY LOW
INVRN HGT/DRY AIR/LARGER SCALE ACYC FLOW/LWRG INVRN HGT WL CONTINUE
NR LK SUP TUE NGT. OVER THE INTERIOR...EXPECT TEMPS TO FALL BLO MOS
GUIDANCE AWAY FM LK MODERATION WITH DIMINISHING WINDS/APRCH OF RDG
AXIS/PWAT ARND 0.1 INCH.
NEXT CLIPPER SHRTWV PROGGED TO DIG INTO THE UPR LKS ON WED...WITH
FAIRLY VIGOROUS DPVA/H85-5 QVECTOR CNVGC CONTIBUTING TO 12Z-24Z H5
HGT FALLS UP TO 60M. BUT DEEPER MSTR FCST TO REMAIN LOCKED UP WITH
SRN BRANCH AND QUITE LIMITED THIS FAR N (GFS FCST PWAT AOB 0.2
INCH). SO THINK ANY SYNOPTIC SN WL BE UNDER AN INCH...WITH THE HIER
POPS CLOSE TO LK SUP WHERE OPPORTUNITY FOR ADDITIONAL LK MOISTENING
WL BE THERE. ARRIVAL OF H85 TEMPS AOB -20C IN THE WAKE OF THIS SYS
WL CRANK UP LES MACHINE WED AFTN/WED NGT...BUT TEMPS MAY BE TOO LO
FOR OPTIMUM SN GROWTH/SGFNT ACCUMULATIONS DESPITE RELATIVELY HI POPS
IN FVRD AREAS NR LK SUP FOR NNW FLOW.
CYC NNE FLOW IN WAKE OF CLIPPER SHRTWV WL BEGIN TO WEAKEN ON THU
UNDER SLOWLY BLDG UPR HGTS/APRCHG ARCTIC HI PRES CENTER. 12Z GFS HAS
TRENDED MUCH FASTER THAN PREVIOUS RUNS/OTHER OPS MODELS/00Z GFS
REFCST ENSEMBLE MEAN...SO REJECTED ITS SOLN FOR TIMING OF SHRTWV AFT
THU. WL MAINTAIN LIKELY POPS NR LK SUP THRU THE DAY PER 12Z ECMWF...
THEN DIMINISH POPS THU NGT WITH APRCH OF SFC RDG AXIS. EXPECT A VERY
COLD NGT WITH TEMPS BLO MOS GUIDANCE OVER THE WCNTRL INTERIOR WITH
LGT WINDS/PCLDY SKIES. UPR RDGING WL DOMINATE ON FRI...AND ANY
LINGERING SHSN WL END EARLY OVER THE E AS LLVL FLOW FCST TO TURN TO
THE SW AHEAD OF NEXT SHRTWV DROPPING THRU SCNTRL CAN. THIS SYS FCST
TO IMPACT THE FA EARLY THIS COMING WEEKEND WITH ONE OF COLDEST
AIRMASSES OF THE SEASON FOLLOWING LATER IN THE WEEKEND (ECMWF FCST
H85 TEMPS TO -22C...GFS FCST TO -26C). ALTHOUGH THE AIRMASS APPEARS
TO BE TOO DRY TO SUPPORT POPS AHEAD OF THE INITIAL COLD FROPA FRI
NGT...EXPECT INCRSG POPS ON SAT WITH ARRIVAL OF UPR TROF/FALLING
HGTS. LES WL BE AN ISSUE ON SAT NGT INTO SUN NGT AS THE COLDER AIR
POURS ACRS LK SUP WITH BLUSTERY NNW WIND. THEN EXPECT A MORE
TRANQUIL DAY ON MON WITH SFC RDG MOVING ACRS THE AREA AS HGTS
RECOVER IN ADVANCE OF ANOTHER CLIPPER SHRTWV. BUT TIMING OF THIS SYS
AS WELL AS POTENTIAL FOR LINGERING LES WARRANT LO CHC POPS THE
ENTIRE DAY.
COORDINATED WITH APX/GRB/DLH.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE
&&
$$
KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
AFDMQT 1115 AM EST MON JAN 22 2007
.UPDATE...
SURFACE TROUGH CURRENTLY FM SE LK SUPERIOR INTO N LK MICHIGAN. AHEAD
OF TROUGH IS SYNOPTIC LIGHT SNOW/FLURRIES. BEHIND TROUGH...WNW WINDS
AND MOISTURE TO AROUND H9 WITH TEMPS AT H9 NEAR -10C IS JUST ENOUGH
TO SUPPORT LIGHT LK EFFECT SNOW SHOWERS. INCREASED POPS AHEAD OF
TROUGH THROUGH EARLY AFTN...THEN DRYING IN THE H9-H8 LAYER AS SEEN
ON UPSTREAM RAOBS AND TAMDAR SOUNDINGS SHOULD DIMINISH THE SNOW. WNW
WINDS BACKING TO SW WILL EVENTUALLY PUSH MOST LK EFFECT OVR KEWEENAW
BY LATE AFTN...WITH A FEW FLURRIES OR DRY WX ELSEWHERE. SOUNDINGS
INDICATE SOME POTENTIAL FOR FREEZING DRIZZLE LATE THIS AFTN INTO THE
EVENING AS MOIST LAYER IS MOST SHALLOW AND TEMPS AT TOP OF MOIST
LAYER ARE BARELY -8C. DEEP MOISTURE IS ALREADY DEPARTING FAR WEST
CWA AND THUS FAR NO FREEZING DRIZZLE OR FLURRIES. CURRENTLY...SFC
DEWPOINT DEPRESSIONS AROUND 5F SO LOOKS TOO DRY IN LOWEST LAYER
FOR THE DRIZZLE. UPSLOPE COMPONENT TO WINDS MAY EVENTUALLY OFFSET
THIS LATER TODAY. HOWEVER...12Z GFS AND LOCAL HIGH RES WRF SOUNDINGS
ARE EVEN DRIER AND WOULD SUGGEST NO PCPN OCCURS DURING THE EVENING.
WILL CONTINUE TO INVESTIGATE DURING THE AFTN...BUT FOR NOW DID NOT
MAKE MAJOR CHANGES TO GOING GRIDS.
SHORTWAVE AND SFC TROUGH OVR NORTHERN MANITOBA WILL DROP SE AND
ACROSS LK SUPERIOR BY LATE TONIGHT...REACHING N UPR MI BY 12Z TUE.
SW/W THEN EVENTUALLY NW FLOW FAVORS KEWEENAW FOR MOST SNOW SHOWERS
TONIGHT. CONVERGENCE AND DEEPER MOISTURE TO ENHANCE LK EFFECT SETUP
WITH OVERALL MARGINAL INSTABILITY (DLT T/S TO INVERSION TOP AROUND
13C) DOES NOT ARRIVE TIL LATER TONIGHT AND 12Z SOUNDINGS ARE A BIT
DRIER WITH THE H9-H8 MOISTURE THAN PREVIOUSLY SHOWN. SO...DELAYED
LIKELY POPS ON KEWEENAW TIL MIDNIGHT.
&&
.DISCUSSION (ISSUED AT 515 AM EST)...
UPPER AIR PATTERN CONSISTS OF A 500 MB CLOSED LOW IN SOUTHERN AZ
WITH A CORRESPONDING TROUGH FROM THE DESERT SW TO THE NORTHERN
PLAINS AND INTO THE UPPER GREAT LAKES WITH RIDGING IN THE PACIFIC NW
AND ALSO ACROSS THE SE.
NAM SHOWING THE 500 MB PATTERN AMPLIFYING WITH THE 500 MB RIDGE
BUILDING INTO THE ROCKIES AND THE TROUGH IN THE EAST DEEPENING WITH
NW-SE FLOW MAINTAINED ACROSS THE AREA IN THE UPPER LEVELS.
NAM SHOWING SOME 850-500 MB Q-VECTOR CONVERGENCE MOVING ACROSS THE
AREA THIS AFTERNOON THROUGH TONIGHT WITH SOME MOISTURE AVAILABLE
TONIGHT. NAM SHOWS MOISTURE ON ISENTROPIC SURFACES FROM I280K-I295K
MOVING THROUGH WHICH IS IN THE MID LEVELS OF THE ATMOSPHERE...BUT
LIFT REMAINS MOSTLY TO THE NORTH OF THE CWA TONIGHT AND THEN
MOISTURE MOVES OUT ON TUE TO THE SOUTH OF THE AREA. GFS SHOWS ABOUT
THE SAME THING ON ITS I280K-I290K SURFACES WITH LIFT STAYING MOSTLY
TO THE NORTH OF THE AREA AND MOISTURE MOVING OUT ON TUE.
FOR TODAY...KEPT A CHANCE OF FLURRIES AND SNOW SHOWERS IN FOR
NORTHWEST AND WEST SNOW BELTS...BUT THINGS SHOULD NOT GET OUT OF
HAND AS 850 MB TEMPERATURES ARE AROUND -7C OR SO WHICH IS BORDERLINE
FOR LAKE EFFECT AND INVERSIONS ARE PRETTY LOW. KEPT IN LOW CHANCE
POPS FOR THIS. FOR TEMPERATURES...WENT CLOSE TO ADJMVR FOR HIGHS
TODAY AND THINK THERE WILL BE CLOUDS FOR MOST OF THE DAY WITH THE
BEST CHANCE FOR SEEING ANY SUNSHINE IN THE EXTREME SOUTH EARLY THIS
AFTERNOON BEFORE MID CLOUDS ARRIVE BY LATE AFTERNOON WITH A
SHORTWAVE MOVING THROUGH THE AREA FOR TONIGHT.
FEELING IS THAT THE SCENARIO TONIGHT AND TUESDAY MORNING WILL PLAY
OUT THIS WAY. THERE WILL BE SOME MID LEVEL MOISTURE...THEN A SMALL
DRY LAYER...THEN MOIST LAYER IN THE LOW LEVELS FOR A SEEDER-FEEDER
MECHANISM AND WENT LOW CHANCE POPS EVERYWHERE AS THE MID LEVEL
MOISTURE SPREADS ACROSS THE CWA. WENT LIKELY POPS IN THE KEWEENAW
WITH SOME LAKE ENHANCEMENT THROWN IN THERE WITH 850 MB TEMPERATURES
AROUND -10C WITH LAKE SUPERIOR TEMPERATURES AT AROUND 3C OR SO WHICH
IS ENOUGH FOR LAKE ENHANCEMENT. WITH WEST WINDS...MADE SENSE TO GO
LIKELY POPS THERE. COLDER AIR ARRIVES IN THE AFTERNOON WITH THE NAM
BRINGING 850 MB TEMPERATURES DOWN TO -12C AND GFS ALSO COOLS THE
TEMPERATURES AND THE WIND SWITCHES TO THE NORTH-NORTHWEST. WENT
LIKELY POPS NEAR LAKE SUPERIOR IN THE AFTERNOON TO ACCOUNT FOR THIS
AND THINK THERE WILL BE A SFC TROUGH GOING THROUGH THE AREA THAT
COULD BRING A BRIEF BURST OF MODERATE TO HEAVY SNOW ALONG IT NEAR
THE LAKE SUPERIOR SHORELINE.
FOR TUE NIGHT THROUGH THU...WENT LIKELY POPS ALONG THE LAKE SUPERIOR
SHORELINE AS THE WIND BECOMES NNW TO N WHICH WILL ALLOW FOR GOOD
LAKE EFFECT. PROBLEM IS THAT DRY AIR IS NOT FAR AWAY AND THERE IS
SOME QUESTION AS TO WHICH WAY THE WINDS WILL BLOW. WENT CLOSE TO THE
ECWMF AND GFS WHICH KEEPS THE WIND MORE NORTHERLY WHILE THE NAM AND
UKMET WANTED TO GO MORE WESTERLY FOR THE WINDS. GFS HAS BEEN
ADVERTISING A DECENT LAKE EFFECT EVENT FOR A WHILE AND WENT TOWARDS
THAT. CONFIDENCE IN THE WINDS IS LOW THOUGH AND DID NOT FEEL
CONFIDENT TO GO WITH ANY HEADLINES YET. THIS WILL CONTINUE TO HAVE
TO BE WATCHED AS THERE COULD BE SOME HEADLINES THAT MIGHT BE NEEDED
AT TIMES. RIGHT NOW...LOOKS LIKE WED NIGHT WOULD HAVE THE BEST
CHANCE FOR HEAVY SNOW WITH STRONG NORTH WINDS. NAM BUFKIT SOUNDINGS
SHOWED INVERSION HEIGHTS GETTING UP TO ABOUT 6000 FEET IN A FEW
PLACES.
OVERALL...MADE A FEW CHANGES TO THE FORECAST AND BUMPED POPS UP A
FEW PLACES. FOR TEMPERATURES...MADE A FEW TWEAKS HERE AND THERE AND
COOLED TEMPERATURES A FEW PLACES. WENT CLOSE TO ADJMVR/ADMXR FOR
TEMPERATURES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE
&&
$$
UPDATE...JLA
DISCUSSION...MICHELS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
AFDRNK 103 PM EST MON JAN 22 2007
.AVIATION /18Z-18Z/...
LOWS CLOUDS AND FOG IN THE EAST WILL LIKELY PERSIST THRU MID AFTN.
ALTHOUGH FINALLY STARTING TO SEE SOME HIGHER CIGS AND VSBYS AT
LYH. VERY DIFFICULT TO KNOW WHEN THINGS WILL BREAK...BUT WILL
CONTINUE TO FCST A GRADUAL IMPROVEMENT OVER THE NEXT SEVERAL
HOURS AT LYH AND DAN. THINGS WILL REMAIN PRETTY MUCH STATUS QUO AT
BLF/LWB/ROA THRU THE AFTN. SNOW SHOWERS INCREASE THIS EVENING IN
THE WEST. EXPECT VFR IN THE EAST TNGT AS WEST WINDS BEGIN TO MIX.
HOWEVER WILL HAVE TO WATCH DAN/LYH AS MIXING MAY NOT PAN OUT AND
THEY COULD FALL INTO A RADIATIONAL FOG SITUATION.
&&
.PREV DISCUSSION...
/ISSUED 1241 PM EST MON JAN 22 2007/
UPDATE...
JUST ABOUT GIVEN UP ON SEEING SUN THE REST OF THE DAY AS IN SITU
DAMMING AND RESULTANT INVERSION ALOFT STILL TOO STRONG FOR LATE
JANUARY SUN TO BREAK...ESP WITH HIGH CLOUDS STILL STREAMING
OVERHEAD. HAVE LOWERED TEMPS IN THE CENTRAL PIEDMONT WHERE TEMPS
STILL NEAR FREEZING.
PREV DISCUSSION...
/ISSUED 1005 AM EST MON JAN 22 2007/
UPDATE...
LOW CLOUDS AND FOG PERSISTING LONGER THAN EXPECTED THIS MORNING
DUE TO STRONG INVERSION ALOFT. WITH COOLER AIR MOVING IN ALOFT AND
SLOW SFC WARMING DURING THE DAY THE INVERSION SHOULD WEAKEN AND
THINGS SHUD BEGIN BREAKING OUT DURING THE EARLY AFTERNOON.
PREV DISCUSSION...
/ISSUED 641 AM EST MON JAN 22 2007/
AVIATION /12Z-12Z/...
SURFACE WINDS WILL BE WEST TO SOUTHWEST TODAY. THIS WILL HELP
RAISE CEILINGS EAST OF THE BLUE RIDGE. CONDIITONS WILL IMPROVE
IN THE EAST BY 18Z...WITH SCATTERED CLOUDS IN THE EVENINGS. IN THE
WEST THE IMPROVEMENT WILL BE VERY SLOW. THE FOG IS NOT EXPECTED TO
LIFT AT BLF UNTIL 15Z...THEN CEILINGS AT BLF AND LWB WILL REMAIN
MVFR THROUGH THE REST OF THE FORECAST PERIOD. A COLD FRONT COMES
THROUGH TONIGHT WITH STRATOCUMULUS AND SNOW SHOWERS ON THE WESTERN
SLOPES OF THE APPALACHIANS. MVFR VISIBILITIES ARE EXPECTED WITH
THE SNOW AT BLF AND LWB LATE TONIGHT.
PREV DISCUSSION...
/ISSUED 441 AM EST MON JAN 22 2007/
SHORT TERM /TODAY THROUGH THURSDAY/...
COUNTY WARNING AREA(CWA) STAYS IN BROAD NORTHWEST FLOW AT 500 MB
THROUGH THURSDAY. SHORT WAVE TROFS MOVE THROUGH THE AREA
TONIGHT...ON WEDNESDAY AFTERNOON AND EVENING...AND ON THURSDAY
MORNING.
MSAS LIFTED INDEX ANALYSIS AND SURFACE OBSERVATIONS SHOW THE
LOCATION OF THE WEDGE FROM RIGHT ALONG THE BLUE RIDGE INTO THE
EASTERN COUNTIES OF THE CWA. THE WEDGE IS FORECAST TO ERODE BETWEEN
BY 18Z TODAY. SURFACE AND LOW LEVEL WINDS BECOMING WEST THIS
MORNING. LITTLE OF ANY DRIZZLE LEFT NOW AND TEMPERATURES WEST OF
THE BLUE RIDGE AND IN NORTH CAROLINA AND EXTREME SOUTHERN VIRGINIA
ARE RISING ABOVE 32 SO ADVISORY WILL BE CANCELLED AT 5AM.
BUT...WITH WEST WIND FOG IN SOUTHEAST WEST VIRGINIA WILL BE SLOW
TO DISSIPATE. MAY BE BREAKS IN THE CLOUDS EAST OF THE BLUE RIDGE
THIS AFTERNOON. BUT WITHOUT MUCH SUN...WITH ICE/SLEET ON THE
GROUND...AND WITH COLD AIR ADVECTION BY THE END OF THE
DAY...WARMING WILL BE SLOW. WENT BELOW COLDEST GUIDANCE FOR HIGH
TEMPERATURES TODAY.
FOR TONIGHT MODELS ARE SHOWING SOME FRONTOGENESIS AND NEGATIVE
EQUIVALENT POTENTIAL VORTICITY WITH THE SHORT WAVE TONIGHT. 850 MB
TEMPERATURES DROP BACK WELL BELOW ZERO WITH 850 MB WINDS IN UP TO 45
KNOTS. SHORT WAVE COMBINED WITH LOW LEVEL MOISTURE AND FAVORABLE
UPSLOPE WINDS WILL PRODUCE SNOW SHOWERS IN THE WESTERN CWA THROUGH
TUESDAY MORNING. AIRMASS DRIES OUT ON TUESDAY WITH LITTLE CLOUDS
COVER LEFT BY THE END OF THE DAY.
ON WEDNESDAY AND WEDNESDAY NIGHT THERE IS Q-VECTOR FORCING WITH THE
SECOND SHORT WAVE. PLENTY OF MOISTURE MOVES BACK INTO THE AREA SO
THE MOUNTAINS WILL AGAIN HAVE A CHANCE OF PRECIPITATION. AT THE
SURFACE LOW PRESSURE THAT DEVELOPS IN THE OHIO RIVER VALLEY WILL
MOVE INTO THE SOUTHERN APPALACHIANS BY WEDNESDAY AFTERNOON. BEHIND
THIS LOW AND ASSOCIATED COLD FRONT ANOTHER SURGE OF COLD AIR MOVES
INTO THE REGION.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
NO CHANGES AT THIS TIME
AVIATION /10Z-06Z/...
PRECIPITATION AXIS DRIFTING TO THE SOUTHEAST THIS EVENING. THIS WILL
DECREASE PRECIPITATION INTENSITIES ACROSS THE AREA.
HOWEVER...THETA-E MOISTURE AXIS AND WEAK WAVE ALOFT TO KEEP DRIZZLE
IN THE AREA THROUGH 10Z MONDAY. STILL SOME AREAS ALONG AND EAST OF
THE BLUE RIDGE WITH TEMPERATURES AT OR BELOW FREEZING...THEREFORE
ADDITIONAL GLAZING FROM FREEZING DRIZZLE IS POSSIBLE. OTHER THAN THE
LIGHT PRECIPITATION...IFR CEILINGS WILL BE A HAZARD FOR AIRCRAFT
THROUGH SUNRISE WITH MOUNTAIN RIDGES OBSCURED. THESE LOW CLOUDS WILL
LINGER IN THE AREA UNTIL MID MORNING...THEN CONDITIONS TO SLOWLY
IMPROVE TO VFR AS WEST WINDS HELP SCOUR LOW LEVEL MOISTURE IN THE
AFTERNOON.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
AVIATION...JS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
AFDRNK 1241 PM EST MON JAN 22 2007
.UPDATE...
JUST ABOUT GIVEN UP ON SEEING SUN THE REST OF THE DAY AS IN SITU
DAMMING AND RESULTANT INVERSION ALOFT STILL TOO STRONG FOR LATE
JANUARY SUN TO BREAK...ESP WITH HIGH CLOUDS STILL STREAMING
OVERHEAD. HAVE LOWERED TEMPS IN THE CENTRAL PIEDMONT WHERE TEMPS
STILL NEAR FREEZING.
&&
.PREV DISCUSSION...
/ISSUED 1005 AM EST MON JAN 22 2007/
UPDATE...
LOW CLOUDS AND FOG PERSISTING LONGER THAN EXPECTED THIS MORNING
DUE TO STRONG INVERSION ALOFT. WITH COOLER AIR MOVING IN ALOFT AND
SLOW SFC WARMING DURING THE DAY THE INVERSION SHOULD WEAKEN AND
THINGS SHUD BEGIN BREAKING OUT DURING THE EARLY AFTERNOON.
PREV DISCUSSION...
/ISSUED 641 AM EST MON JAN 22 2007/
AVIATION /12Z-12Z/...
SURFACE WINDS WILL BE WEST TO SOUTHWEST TODAY. THIS WILL HELP
RAISE CEILINGS EAST OF THE BLUE RIDGE. CONDIITONS WILL IMPROVE
IN THE EAST BY 18Z...WITH SCATTERED CLOUDS IN THE EVENINGS. IN THE
WEST THE IMPROVEMENT WILL BE VERY SLOW. THE FOG IS NOT EXPECTED TO
LIFT AT BLF UNTIL 15Z...THEN CEILINGS AT BLF AND LWB WILL REMAIN
MVFR THROUGH THE REST OF THE FORECAST PERIOD. A COLD FRONT COMES
THROUGH TONIGHT WITH STRATOCUMULUS AND SNOW SHOWERS ON THE WESTERN
SLOPES OF THE APPALACHIANS. MVFR VISIBILITIES ARE EXPECTED WITH
THE SNOW AT BLF AND LWB LATE TONIGHT.
PREV DISCUSSION...
/ISSUED 441 AM EST MON JAN 22 2007/
SHORT TERM /TODAY THROUGH THURSDAY/...
COUNTY WARNING AREA(CWA) STAYS IN BROAD NORTHWEST FLOW AT 500 MB
THROUGH THURSDAY. SHORT WAVE TROFS MOVE THROUGH THE AREA
TONIGHT...ON WEDNESDAY AFTERNOON AND EVENING...AND ON THURSDAY
MORNING.
MSAS LIFTED INDEX ANALYSIS AND SURFACE OBSERVATIONS SHOW THE
LOCATION OF THE WEDGE FROM RIGHT ALONG THE BLUE RIDGE INTO THE
EASTERN COUNTIES OF THE CWA. THE WEDGE IS FORECAST TO ERODE BETWEEN
BY 18Z TODAY. SURFACE AND LOW LEVEL WINDS BECOMING WEST THIS
MORNING. LITTLE OF ANY DRIZZLE LEFT NOW AND TEMPERATURES WEST OF
THE BLUE RIDGE AND IN NORTH CAROLINA AND EXTREME SOUTHERN VIRGINIA
ARE RISING ABOVE 32 SO ADVISORY WILL BE CANCELLED AT 5AM.
BUT...WITH WEST WIND FOG IN SOUTHEAST WEST VIRGINIA WILL BE SLOW
TO DISSIPATE. MAY BE BREAKS IN THE CLOUDS EAST OF THE BLUE RIDGE
THIS AFTERNOON. BUT WITHOUT MUCH SUN...WITH ICE/SLEET ON THE
GROUND...AND WITH COLD AIR ADVECTION BY THE END OF THE
DAY...WARMING WILL BE SLOW. WENT BELOW COLDEST GUIDANCE FOR HIGH
TEMPERATURES TODAY.
FOR TONIGHT MODELS ARE SHOWING SOME FRONTOGENESIS AND NEGATIVE
EQUIVALENT POTENTIAL VORTICITY WITH THE SHORT WAVE TONIGHT. 850 MB
TEMPERATURES DROP BACK WELL BELOW ZERO WITH 850 MB WINDS IN UP TO 45
KNOTS. SHORT WAVE COMBINED WITH LOW LEVEL MOISTURE AND FAVORABLE
UPSLOPE WINDS WILL PRODUCE SNOW SHOWERS IN THE WESTERN CWA THROUGH
TUESDAY MORNING. AIRMASS DRIES OUT ON TUESDAY WITH LITTLE CLOUDS
COVER LEFT BY THE END OF THE DAY.
ON WEDNESDAY AND WEDNESDAY NIGHT THERE IS Q-VECTOR FORCING WITH THE
SECOND SHORT WAVE. PLENTY OF MOISTURE MOVES BACK INTO THE AREA SO
THE MOUNTAINS WILL AGAIN HAVE A CHANCE OF PRECIPITATION. AT THE
SURFACE LOW PRESSURE THAT DEVELOPS IN THE OHIO RIVER VALLEY WILL
MOVE INTO THE SOUTHERN APPALACHIANS BY WEDNESDAY AFTERNOON. BEHIND
THIS LOW AND ASSOCIATED COLD FRONT ANOTHER SURGE OF COLD AIR MOVES
INTO THE REGION.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
NO CHANGES AT THIS TIME
AVIATION /10Z-06Z/...
PRECIPITATION AXIS DRIFTING TO THE SOUTHEAST THIS EVENING. THIS WILL
DECREASE PRECIPITATION INTENSITIES ACROSS THE AREA.
HOWEVER...THETA-E MOISTURE AXIS AND WEAK WAVE ALOFT TO KEEP DRIZZLE
IN THE AREA THROUGH 10Z MONDAY. STILL SOME AREAS ALONG AND EAST OF
THE BLUE RIDGE WITH TEMPERATURES AT OR BELOW FREEZING...THEREFORE
ADDITIONAL GLAZING FROM FREEZING DRIZZLE IS POSSIBLE. OTHER THAN THE
LIGHT PRECIPITATION...IFR CEILINGS WILL BE A HAZARD FOR AIRCRAFT
THROUGH SUNRISE WITH MOUNTAIN RIDGES OBSCURED. THESE LOW CLOUDS WILL
LINGER IN THE AREA UNTIL MID MORNING...THEN CONDITIONS TO SLOWLY
IMPROVE TO VFR AS WEST WINDS HELP SCOUR LOW LEVEL MOISTURE IN THE
AFTERNOON.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
UPDATE...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
AFDRNK 1005 AM EST MON JAN 22 2007
.UPDATE...
LOW CLOUDS AND FOG PERSISTING LONGER THAN EXPECTED THIS MORNING
DUE TO STRONG INVERSION ALOFT. WITH COOLER AIR MOVING IN ALOFT AND
SLOW SFC WARMING DURING THE DAY THE INVERSION SHOULD WEAKEN AND
THINGS SHUD BEGIN BREAKING OUT DURING THE EARLY AFTERNOON.
&&
.PREV DISCUSSION...
/ISSUED 641 AM EST MON JAN 22 2007/
AVIATION /12Z-12Z/...
SURFACE WINDS WILL BE WEST TO SOUTHWEST TODAY. THIS WILL HELP
RAISE CEILINGS EAST OF THE BLUE RIDGE. CONDIITONS WILL IMPROVE
IN THE EAST BY 18Z...WITH SCATTERED CLOUDS IN THE EVENINGS. IN THE
WEST THE IMPROVEMENT WILL BE VERY SLOW. THE FOG IS NOT EXPECTED TO
LIFT AT BLF UNTIL 15Z...THEN CEILINGS AT BLF AND LWB WILL REMAIN
MVFR THROUGH THE REST OF THE FORECAST PERIOD. A COLD FRONT COMES
THROUGH TONIGHT WITH STRATOCUMULUS AND SNOW SHOWERS ON THE WESTERN
SLOPES OF THE APPALACHIANS. MVFR VISIBILITIES ARE EXPECTED WITH
THE SNOW AT BLF AND LWB LATE TONIGHT.
PREV DISCUSSION...
/ISSUED 441 AM EST MON JAN 22 2007/
SHORT TERM /TODAY THROUGH THURSDAY/...
COUNTY WARNING AREA(CWA) STAYS IN BROAD NORTHWEST FLOW AT 500 MB
THROUGH THURSDAY. SHORT WAVE TROFS MOVE THROUGH THE AREA
TONIGHT...ON WEDNESDAY AFTERNOON AND EVENING...AND ON THURSDAY
MORNING.
MSAS LIFTED INDEX ANALYSIS AND SURFACE OBSERVATIONS SHOW THE
LOCATION OF THE WEDGE FROM RIGHT ALONG THE BLUE RIDGE INTO THE
EASTERN COUNTIES OF THE CWA. THE WEDGE IS FORECAST TO ERODE BETWEEN
BY 18Z TODAY. SURFACE AND LOW LEVEL WINDS BECOMING WEST THIS
MORNING. LITTLE OF ANY DRIZZLE LEFT NOW AND TEMPERATURES WEST OF
THE BLUE RIDGE AND IN NORTH CAROLINA AND EXTREME SOUTHERN VIRGINIA
ARE RISING ABOVE 32 SO ADVISORY WILL BE CANCELLED AT 5AM.
BUT...WITH WEST WIND FOG IN SOUTHEAST WEST VIRGINIA WILL BE SLOW
TO DISSIPATE. MAY BE BREAKS IN THE CLOUDS EAST OF THE BLUE RIDGE
THIS AFTERNOON. BUT WITHOUT MUCH SUN...WITH ICE/SLEET ON THE
GROUND...AND WITH COLD AIR ADVECTION BY THE END OF THE
DAY...WARMING WILL BE SLOW. WENT BELOW COLDEST GUIDANCE FOR HIGH
TEMPERATURES TODAY.
FOR TONIGHT MODELS ARE SHOWING SOME FRONTOGENESIS AND NEGATIVE
EQUIVALENT POTENTIAL VORTICITY WITH THE SHORT WAVE TONIGHT. 850 MB
TEMPERATURES DROP BACK WELL BELOW ZERO WITH 850 MB WINDS IN UP TO 45
KNOTS. SHORT WAVE COMBINED WITH LOW LEVEL MOISTURE AND FAVORABLE
UPSLOPE WINDS WILL PRODUCE SNOW SHOWERS IN THE WESTERN CWA THROUGH
TUESDAY MORNING. AIRMASS DRIES OUT ON TUESDAY WITH LITTLE CLOUDS
COVER LEFT BY THE END OF THE DAY.
ON WEDNESDAY AND WEDNESDAY NIGHT THERE IS Q-VECTOR FORCING WITH THE
SECOND SHORT WAVE. PLENTY OF MOISTURE MOVES BACK INTO THE AREA SO
THE MOUNTAINS WILL AGAIN HAVE A CHANCE OF PRECIPITATION. AT THE
SURFACE LOW PRESSURE THAT DEVELOPS IN THE OHIO RIVER VALLEY WILL
MOVE INTO THE SOUTHERN APPALACHIANS BY WEDNESDAY AFTERNOON. BEHIND
THIS LOW AND ASSOCIATED COLD FRONT ANOTHER SURGE OF COLD AIR MOVES
INTO THE REGION.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
NO CHANGES AT THIS TIME
AVIATION /10Z-06Z/...
PRECIPITATION AXIS DRIFTING TO THE SOUTHEAST THIS EVENING. THIS WILL
DECREASE PRECIPITATION INTENSITIES ACROSS THE AREA.
HOWEVER...THETA-E MOISTURE AXIS AND WEAK WAVE ALOFT TO KEEP DRIZZLE
IN THE AREA THROUGH 10Z MONDAY. STILL SOME AREAS ALONG AND EAST OF
THE BLUE RIDGE WITH TEMPERATURES AT OR BELOW FREEZING...THEREFORE
ADDITIONAL GLAZING FROM FREEZING DRIZZLE IS POSSIBLE. OTHER THAN THE
LIGHT PRECIPITATION...IFR CEILINGS WILL BE A HAZARD FOR AIRCRAFT
THROUGH SUNRISE WITH MOUNTAIN RIDGES OBSCURED. THESE LOW CLOUDS WILL
LINGER IN THE AREA UNTIL MID MORNING...THEN CONDITIONS TO SLOWLY
IMPROVE TO VFR AS WEST WINDS HELP SCOUR LOW LEVEL MOISTURE IN THE
AFTERNOON.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
UPDATE...
SHORT TERM...JS
AREA FORECAST DISCUSSION...UPDATED
NWS BLACKSBURG VA
AFDRNK 641 AM EST MON JAN 22 2007
.AVIATION /12Z-12Z/...
SURFACE WINDS WILL BE WEST TO SOUTHWEST TODAY. THIS WILL HELP
RAISE CEILINGS EAST OF THE BLUE RIDGE. CONDIITONS WILL IMPROVE
IN THE EAST BY 18Z...WITH SCATTERED CLOUDS IN THE EVENINGS. IN THE
WEST THE IMPROVEMENT WILL BE VERY SLOW. THE FOG IS NOT EXPECTED TO
LIFT AT BLF UNTIL 15Z...THEN CEILINGS AT BLF AND LWB WILL REMAIN
MVFR THROUGH THE REST OF THE FORECAST PERIOD. A COLD FRONT COMES
THROUGH TONIGHT WITH STRATOCUMULUS AND SNOW SHOWERS ON THE WESTERN
SLOPES OF THE APPALACHIANS. MVFR VISIBILITIES ARE EXPECTED WITH
THE SNOW AT BLF AND LWB LATE TONIGHT.
&&
.PREV DISCUSSION...
/ISSUED 441 AM EST MON JAN 22 2007/
SHORT TERM /TODAY THROUGH THURSDAY/...
COUNTY WARNING AREA(CWA) STAYS IN BROAD NORTHWEST FLOW AT 500 MB
THROUGH THURSDAY. SHORT WAVE TROFS MOVE THROUGH THE AREA
TONIGHT...ON WEDNESDAY AFTERNOON AND EVENING...AND ON THURSDAY
MORNING.
MSAS LIFTED INDEX ANALYSIS AND SURFACE OBSERVATIONS SHOW THE
LOCATION OF THE WEDGE FROM RIGHT ALONG THE BLUE RIDGE INTO THE
EASTERN COUNTIES OF THE CWA. THE WEDGE IS FORECAST TO ERODE BETWEEN
BY 18Z TODAY. SURFACE AND LOW LEVEL WINDS BECOMING WEST THIS
MORNING. LITTLE OF ANY DRIZZLE LEFT NOW AND TEMPERATURES WEST OF
THE BLUE RIDGE AND IN NORTH CAROLINA AND EXTREME SOUTHERN VIRGINIA
ARE RISING ABOVE 32 SO ADVISORY WILL BE CANCELLED AT 5AM.
BUT...WITH WEST WIND FOG IN SOUTHEAST WEST VIRGINIA WILL BE SLOW
TO DISSIPATE. MAY BE BREAKS IN THE CLOUDS EAST OF THE BLUE RIDGE
THIS AFTERNOON. BUT WITHOUT MUCH SUN...WITH ICE/SLEET ON THE
GROUND...AND WITH COLD AIR ADVECTION BY THE END OF THE
DAY...WARMING WILL BE SLOW. WENT BELOW COLDEST GUIDANCE FOR HIGH
TEMPERATURES TODAY.
FOR TONIGHT MODELS ARE SHOWING SOME FRONTOGENESIS AND NEGATIVE
EQUIVALENT POTENTIAL VORTICITY WITH THE SHORT WAVE TONIGHT. 850 MB
TEMPERATURES DROP BACK WELL BELOW ZERO WITH 850 MB WINDS IN UP TO 45
KNOTS. SHORT WAVE COMBINED WITH LOW LEVEL MOISTURE AND FAVORABLE
UPSLOPE WINDS WILL PRODUCE SNOW SHOWERS IN THE WESTERN CWA THROUGH
TUESDAY MORNING. AIRMASS DRIES OUT ON TUESDAY WITH LITTLE CLOUDS
COVER LEFT BY THE END OF THE DAY.
ON WEDNESDAY AND WEDNESDAY NIGHT THERE IS Q-VECTOR FORCING WITH THE
SECOND SHORT WAVE. PLENTY OF MOISTURE MOVES BACK INTO THE AREA SO
THE MOUNTAINS WILL AGAIN HAVE A CHANCE OF PRECIPITATION. AT THE
SURFACE LOW PRESSURE THAT DEVELOPS IN THE OHIO RIVER VALLEY WILL
MOVE INTO THE SOUTHERN APPALACHIANS BY WEDNESDAY AFTERNOON. BEHIND
THIS LOW AND ASSOCIATED COLD FRONT ANOTHER SURGE OF COLD AIR MOVES
INTO THE REGION.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
NO CHANGES AT THIS TIME
AVIATION /10Z-06Z/...
PRECIPITATION AXIS DRIFTING TO THE SOUTHEAST THIS EVENING. THIS WILL
DECREASE PRECIPITATION INTENSITIES ACROSS THE AREA.
HOWEVER...THETA-E MOISTURE AXIS AND WEAK WAVE ALOFT TO KEEP DRIZZLE
IN THE AREA THROUGH 10Z MONDAY. STILL SOME AREAS ALONG AND EAST OF
THE BLUE RIDGE WITH TEMPERATURES AT OR BELOW FREEZING...THEREFORE
ADDITIONAL GLAZING FROM FREEZING DRIZZLE IS POSSIBLE. OTHER THAN THE
LIGHT PRECIPITATION...IFR CEILINGS WILL BE A HAZARD FOR AIRCRAFT
THROUGH SUNRISE WITH MOUNTAIN RIDGES OBSCURED. THESE LOW CLOUDS WILL
LINGER IN THE AREA UNTIL MID MORNING...THEN CONDITIONS TO SLOWLY
IMPROVE TO VFR AS WEST WINDS HELP SCOUR LOW LEVEL MOISTURE IN THE
AFTERNOON.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
AFDRNK 441 AM EST MON JAN 22 2007
.SHORT TERM /TODAY THROUGH THURSDAY/...
COUNTY WARNING AREA(CWA) STAYS IN BROAD NORTHWEST FLOW AT 500 MB
THROUGH THURSDAY. SHORT WAVE TROFS MOVE THROUGH THE AREA
TONIGHT...ON WEDNESDAY AFTERNOON AND EVENING...AND ON THURSDAY
MORNING.
MSAS LIFTED INDEX ANALYSIS AND SURFACE OBSERVATIONS SHOW THE
LOCATION OF THE WEDGE FROM RIGHT ALONG THE BLUE RIDGE INTO THE
EASTERN COUNTIES OF THE CWA. THE WEDGE IS FORECAST TO ERODE BETWEEN
BY 18Z TODAY. SURFACE AND LOW LEVEL WINDS BECOMING WEST THIS
MORNING. LITTLE OF ANY DRIZZLE LEFT NOW AND TEMPERATURES WEST OF
THE BLUE RIDGE AND IN NORTH CAROLINA AND EXTREME SOUTHERN VIRGINIA
ARE RISING ABOVE 32 SO ADVISORY WILL BE CANCELLED AT 5AM.
BUT...WITH WEST WIND FOG IN SOUTHEAST WEST VIRGINIA WILL BE SLOW
TO DISSIPATE. MAY BE BREAKS IN THE CLOUDS EAST OF THE BLUE RIDGE
THIS AFTERNOON. BUT WITHOUT MUCH SUN...WITH ICE/SLEET ON THE
GROUND...AND WITH COLD AIR ADVECTION BY THE END OF THE
DAY...WARMING WILL BE SLOW. WENT BELOW COLDEST GUIDANCE FOR HIGH
TEMPERATURES TODAY.
FOR TONIGHT MODELS ARE SHOWING SOME FRONTOGENESIS AND NEGATIVE
EQUIVALENT POTENTIAL VORTICITY WITH THE SHORT WAVE TONIGHT. 850 MB
TEMPERATURES DROP BACK WELL BELOW ZERO WITH 850 MB WINDS IN UP TO 45
KNOTS. SHORT WAVE COMBINED WITH LOW LEVEL MOISTURE AND FAVORABLE
UPSLOPE WINDS WILL PRODUCE SNOW SHOWERS IN THE WESTERN CWA THROUGH
TUESDAY MORNING. AIRMASS DRIES OUT ON TUESDAY WITH LITTLE CLOUDS
COVER LEFT BY THE END OF THE DAY.
ON WEDNESDAY AND WEDNESDAY NIGHT THERE IS Q-VECTOR FORCING WITH THE
SECOND SHORT WAVE. PLENTY OF MOISTURE MOVES BACK INTO THE AREA SO
THE MOUNTAINS WILL AGAIN HAVE A CHANCE OF PRECIPITATION. AT THE
SURFACE LOW PRESSURE THAT DEVELOPS IN THE OHIO RIVER VALLEY WILL
MOVE INTO THE SOUTHERN APPALACHIANS BY WEDNESDAY AFTERNOON. BEHIND
THIS LOW AND ASSOCIATED COLD FRONT ANOTHER SURGE OF COLD AIR MOVES
INTO THE REGION.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
NO CHANGES AT THIS TIME
&&
.AVIATION /10Z-06Z/...
PRECIPITATION AXIS DRIFTING TO THE SOUTHEAST THIS EVENING. THIS WILL
DECREASE PRECIPITATION INTENSITIES ACROSS THE AREA.
HOWEVER...THETA-E MOISTURE AXIS AND WEAK WAVE ALOFT TO KEEP DRIZZLE
IN THE AREA THROUGH 10Z MONDAY. STILL SOME AREAS ALONG AND EAST OF
THE BLUE RIDGE WITH TEMPERATURES AT OR BELOW FREEZING...THEREFORE
ADDITIONAL GLAZING FROM FREEZING DRIZZLE IS POSSIBLE. OTHER THAN THE
LIGHT PRECIPITATION...IFR CEILINGS WILL BE A HAZARD FOR AIRCRAFT
THROUGH SUNRISE WITH MOUNTAIN RIDGES OBSCURED. THESE LOW CLOUDS WILL
LINGER IN THE AREA UNTIL MID MORNING...THEN CONDITIONS TO SLOWLY
IMPROVE TO VFR AS WEST WINDS HELP SCOUR LOW LEVEL MOISTURE IN THE
AFTERNOON.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...RCS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
AFDRNK 1245 AM EST MON JAN 22 2007
.AVIATION /05Z-24Z/...
PRECIPITATION AXIS DRIFTING TO THE SOUTHEAST THIS EVENING. THIS WILL
DECREASE PRECIPITATION INTENSITIES ACROSS THE AREA.
HOWEVER...THETA-E MOISTURE AXIS AND WEAK WAVE ALOFT TO KEEP DRIZZLE
IN THE AREA THROUGH 10Z MONDAY. STILL SOME AREAS ALONG AND EAST OF
THE BLUE RIDGE WITH TEMPERATURES AT OR BELOW FREEZING...THEREFORE
ADDITIONAL GLAZING FROM FREEZING DRIZZLE IS POSSIBLE. OTHER THAN THE
LIGHT PRECIPITATION...IFR CEILINGS WILL BE A HAZARD FOR AIRCRAFT
THROUGH SUNRISE WITH MOUNTAIN RIDGES OBSCURED. THESE LOW CLOUDS WILL
LINGER IN THE AREA UNTIL MID MORNING...THEN CONDITIONS TO SLOWLY
IMPROVE TO VFR AS WEST WINDS HELP SCOUR LOW LEVEL MOISTURE IN THE
AFTERNOON.
&&
.PREV DISCUSSION...
/ISSUED 1210 AM EST MON JAN 22 2007/
UPDATE...
WILL BE UPDATING ZONES TO REMOVE MIDNIGHT WORDING. EXPECT ONLY
STEADY TEMPERATURES OR A ONE OR TWO DEGREE RISE OVERNIGHT. NO
CHANGES TO THE ADVISORY AT THIS TIME.
PREV DISCUSSION...
/ISSUED 853 PM EST SUN JAN 21 2007/
UPDATE...
UPDATED THE WARNINGS AND DROPPED THOSE TO WINTER WX
ADVISORY...EXCEPT CLEARED AREAS WHERE TEMPS ARE AT OR ABOVE
FREEZING OVERNIGHT. STILL EXPECTING LIGHT ICING FROM
-FZRA/FZDZ...ESPECIALLY EAST OF THE BLUE RIDGE TOWARD LYH OVERNIGHT.
SHORT TERM /REST OF TONIGHT/...
WARM AIR HAS MADE INROADS INTO THE TYPICAL NON-WEDGED
LOCATIONS...THAT IS BLF-6V3-VJI-TNB. THIS WARM AIR WILL CONTINUE
TO WORK ITS WAY INTO SW VA OVERNIGHT...BUT TEMPS FURTHER NORTH AND
EAST WILL REMAIN AT OR BELOW FREEZING. LOW PRESSURE MOVING OFF THE
NC COAST 12Z MONDAY WILL END ANY MEASURABLE PRECIP WITH LINGERING
DRIZZLE IN SE WV. SOUNDINGS SHOW THAT PRECIP SHOULD CHANGE TO MORE
OF A DRIZZLE/FREEZING DRIZZLE SCENARIO AFT 06Z...EARLY FOR
LOCATIONS FURTHER WEST. MADE TWEAKS TO TEMPS BASED ON CURRENT
CONDITIONS AND ADJUSTED TOWARD MAV MOS USING SOME CORRECTION UP OR
DOWN BASED ON WHERE THE WEDGE WILL REMAIN.
PREV DISCUSSION...
/ISSUED 643 PM EST SUN JAN 21 2007/
AVIATION /00Z-24Z/...
STORM SYSTEM OVER THE SOUTH WILL BEGIN SHIFTING EAST AND OUT OF
THE AREA LATE TONIGHT. WINTRY PRECIP WILL HANG AROUND FOR MOST OF
THE NIGHT THIS EVENING...ESPECIALLY EAST OF THE BLUE RIDGE TOWARD
LYH. CIGS WILL BE THE MAIN AVIATION CONCERN AS THEY LOWER BELOW
1000 FT AT ALL TAF SITES. VLIFR/IFR CONDITIONS WILL DOMINATE THE
OVERNIGHT...WITH ROA/LYH/DAN SEEING CIGS IMPROVE AFT 12Z MON.
FREEZING PRECIP WILL TAPER TO DRIZZLE BEFORE 12Z. ENOUGH MIXING
MONDAY AFTERNOON WILL BRING VFR CONDITIONS TO THE PIEDMONT AND ROA
VALLEY...WITH SE WV IMPROVING JUST TO LOW MVFR AT BEST.
PREV DISCUSSION...
/ISSUED 306 PM EST SUN JAN 21 2007/
SHORT TERM /TONIGHT/...
UPWARD VERTICAL MOTION FIELDS WILL GRADUALLY WEAKEN EARLY TONIGHT AS
WARM AIR ADVECTION AND ASSOCIATED ISENTROPIC LIFT MOVES OFF TO THE
NORTH AND EAST...LEAVING BLACKSBURG FORECAST AREA IN MAINLY NEUTRAL
ADVECTION ZONE UNTIL LATER TONIGHT WHEN SHORT WAVE TROF PASSES
THROUGH AREA AND WEAK COLD AIR ADVECTION BEGINS FROM NORTHWEST TO
SOUTHEAST.
LARGE AREA OF FREEZING RAIN...WITH SOME ICE PELLETS PERSISTING
ACROSS NORTHERN AREAS...WILL GRADUALLY DIMINISH EARLY TONIGHT...AND
TRANSITION OVER TO MORE OF A LIGHT FREEZING DRIZZLE OR DRIZZLE WITH
PASSAGE OF WAVE AS MID AND UPPER LEVEL MOISTURE IS LOST...LEAVING
SHALLOW MOISTURE POOL TRAPPED BELOW INVERSION LAYER.
LIMITED SURFACE MIXING UNDER COOL WEDGE TOPPED BY WARM ADVECTION
WILL RESULT IN LITTLE OR NO TEMPERATURE DECREASE TONIGHT...WITH EVEN
A SLOW RISE EXPECTED ACROSS THE NORTHWEST (LATE) WHEN SURFACE MIXING
BEGINS IN ASSOCIATION WITH WEAK COOL ADVECTION AND INCREASING
PRESSURE GRADIENT BEHIND SURFACE LOW...AND ACROSS THE PIEDMONT WHERE
TEMPERATURES ALOFT WILL BE THE WARMEST.
CONSIDERING THE VERY SLUGGISH TEMPERATURE RECOVERY UNDER THE COOL
WEDGE...SOME SHELTERED AREAS AND HIGHER RIDGES WILL NOT EXPERIENCE
ABOVE FREEZING TEMPERATURES UNTIL LATE TONIGHT...POSSIBLY NOT UNTIL
AROUND OR SHORTLY AFTER DAYBREAK. THEREFORE...WILL CONTINUE WITH
EXISTING WARNINGS AND ADVISORIES WITH NO SIGNIFICANT CHANGES
TEMPORALLY OR SPATIALLY.
LONG TERM /MONDAY THROUGH SUNDAY/...
BY MONDAY MORNING...THE BULK OF THE MOISTURE ASSOCIATED WITH THE
EXITING SYSTEM SHOULD HAVE ALSO EXITED THE REGION. WHAT LOOKS TO
REMAIN WILL SOME SHALLOW LOW CLOUDS ACROSS THE AREA...ESPECIALLY
OVER SE WV AND NEIGHBORING SW VA. ALSO IN THIS AREA...LINGERING
PATCHY PRECIPITATION SHOULD CONTINUE THROUGH THE DAY. WITH ANY
SATURATED LAYERS BELOW -10 C LACKING...EXPECT THE PRECIPITATION TO
BE IN THE FORM OF DRIZZLE OR FREEZING DRIZZLE...DEPENDING UPON THE
LOCAL SURFACE TEMPERATURE. DESPITE THE CLOUD COVER...GOOD WARM AIR
ADVECTION SHOULD PROVIDE FOR TEMPERATURES REACHING VALUES AT...OR
SLIGHTLY ABOVE...SEASONAL NORMALS.
HEADING INTO MID-WEEK...THE OVERALL SYNOPTIC PATTERN WILL BE
DOMINATED BY A LOW PRESSURE SYSTEM THAT LOOKS TO PARK ITSELF OVER
QUEBEC...ALLOWING FOR A PREDOMINATELY NORTHWEST FLOW AND COLD AIR
ADVECTION...INTO THE REGION. THIS PATTERN WILL KEEP RESIDUAL LOW
LEVEL MOISTURE BEING LIFTED UPSLOPE ACROSS SE WV...AND WITH
COOLING TEMPERATURES IN THE LOW LEVELS...WE SHOULD START TO SEE
BETTER POTENTIAL FOR ICE CRYSTAL GROWTH SOMETIME LATE MONDAY
EVENING...AND THEN THROUGH THE REST OF MONDAY NIGHT INTO THE DAY
ON TUESDAY. LITTLE ACCUMULATION OF SNOW IS EXPECTED.
ALSO AS PART OF THIS OVERALL SYNOPTIC PATTERN WILL BE A CUT-OFF LOW
OVER THE THE NORTHERN STATES OF MEXICO AND A PREVAILING SUB-TROPICAL
JET PROGRESSING FROM THE WESTERN PORTION OF THE GULF OF MEXICO
ACROSS FLORIDA.
THERE HAD BEEN SOME CONCERN FOR THE TIME PERIOD OF WEDNESDAY THROUGH
THURSDAY NIGHT OF A SYSTEM MOVING THROUGH THE NORTHERN STREAM BRANCH
PHASING WITH...OR COME CLOSE TO PHASING WITH...A SOUTHERN STREAM
BRANCH AND PROVIDING FOR A SUBSTANTIAL WINTER SYSTEM FOR THE AREA
DURING THE TIME PERIOD. THE TREND TODAY HAS BEEN FOR THESE SYSTEMS
TO STAY LESS-PHASED THAN EARLIER RUNS SUGGESTED THEY MIGHT COME
CLOSE TO DOING. ACCORDINGLY...THE PREFERRED GUIDANCE FROM HPC HAS
LOWERED CHANCES OF PRECIPITATION WEDNESDAY THROUGH THURSDAY NIGHT
AS COMPARED TO ITS PREVIOUS SOLUTION. THIS PRECIPITATION WILL
PRIMARILY BE IN THE FORM OF SNOW FROM NORTHWEST FLOW UPSLOPE
FORCING OVER SE WV AND NEIGHBORING SW VA AND FAR NW NC. ALTHOUGH
DURING THE AFTERNOON WEDNESDAY...IT MAY START AS A MIX OF RAIN OR
SNOW DEPENDING UPON LOCAL TEMPERATURES. LITTLE IF ANY
PRECIPITATION IS EXPECTED EAST OF THE BLUE RIDGE.
AFTER A SMALL BREAK IN THE ACTIVITY FRIDAY AND FRIDAY
NIGHT...ANOTHER NORTHWEST FLOW DISTURBANCE WILL BRING A RETURN OF
SCATTERED SNOW SHOWERS TO THE MOUNTAINS FOR THE WEEKEND.
AVIATION /20Z-18Z/...
EXPECT TO SEE ALL BLACKSBURG TERMINAL FORECAST POINTS
(ROANOKE...LYNCHBURG...DANVILLE...BLUEFIELD...LEWISBURG) TO SEE
GRADUAL REDUCTION TO INSTRUMENT FLIGHT RULE RESTRICTIONS IN
CEILING..AND PERHAPS VISIBILITY...AS LOWER ATMOSPHERE SATURATES
DUE TO PRECIPITATION. WARM AIR ALOFT NOW SUFFICIENTLY DEEP THAT
ALL PRECIPITATION HAS CHANGED OVER TO FREEZING RAIN...AND THIS
LIKELY TO CONTINUE UNTIL AT LEAST EARLY TONIGHT BEFORE BEST AREA
OF LIFT AND MOISTURE MOVES OFF TO THE EAST.
WILL BEGIN TO SEE GRADUAL IMPROVEMENT BACK TO MARGINAL FLIGHT RULE
RESTRICTIONS IN CEILING...WITH NO VISIBILITY RESTRICTION...BY OR
SHORTLY AFTER DAYBREAK MONDAY AS DOWNSLOPE WINDS BEGIN TO IMPACT
AREAS EAST OF THE BLUE RIDGE. FURTHER WEST AT BLUEFIELD AND
LEWISBURG...INCREASING UPSLOPE CONDITIONS WILL LIKELY DELAY
IMPROVEMENT IN WEATHER UNTIL MID-LATE MORNING.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
VAZ011>020-022>024-032>035-043>047-058-059.
NC...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
NCZ002>006.
WV...WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
WVZ043>045.
&&
$$
UPDATE...
AVIATION...RCS