AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSGX 350 AM PST WED FEB 7 2007
.SYNOPSIS...
A DEVELOPING TROUGH OF LOW PRESSURE OVER THE EASTERN PACIFIC WILL
BRING A COOLING TREND AND INCREASING CLOUDS THROUGH FRIDAY. THIS
TROUGH OF LOW PRESSURE MAY MOVE INLAND ACROSS CALIFORNIA DURING THE
WEEKEND THROUGH EARLY NEXT WEEK BRINGING A CHANCE OF PRECIPITATION
TO SOUTHWEST CALIFORNIA.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH FRIDAY)...
DENSE FOG ADVISORY EXTENDED FOR COASTAL AREAS UNTIL 8 AM AND
EXPANDED INTO THE SAN DIEGO COUNTY VALLEYS. ACARS SOUNDINGS SHOW A
SHALLOW MARINE INVERSION WITH THE BASE BELOW 1000 FEET. SURFACE
REPORTS SHOW AREAS OF DENSE FOG PERSISTING ALONG THE COAST EXTENDING
INLAND TO THE LOWER COASTAL VALLEYS. SOME DEEPENING OF THE MARINE
LAYER IS EXPECTED WITH THE APPROACHING TROUGH OVER THE EASTERN
PACIFIC THOUGH THIS HAS BEEN SLOW TO OCCUR. SOME DEEPENING IS
SUGGEST BY SURFACE OBSERVATIONS IN SAN DIEGO COUNTY THE PAST TWO
HOURS WITH SOME SLOW IMPROVEMENT IN THE VISIBILITY AT LINDBERGH
FIELD WITH DENSE FOG SPREADING INLAND TO MIRAMAR AND MONTGOMERY.
WHILE SOME SLOW DEEPENING MAY OCCUR THROUGH SUNRISE...THIS MAY NOT
BE SUFFICIENT OR FAST ENOUGH TO RESULT IN WIDESPREAD IMPROVEMENT IN
VISIBILITIES IN THE COASTAL ZONES UNTIL SOME TIME AFTER 6 AM.
OTHERWISE...THE DEVELOPING TROUGH OF LOW PRESSURE OVER THE EASTERN
PACIFIC WILL CONTINUE THE COOLING TREND THROUGH FRIDAY WITH VARIABLE
HIGH CLOUDS AND SOME OVERNIGHT MARINE LAYER CLOUDINESS.
PRECIPITATION THROUGH FRIDAY WILL MOSTLY BE DIRECTED INTO NORTHERN
AND CENTRAL CALIFORNIA...THOUGH THERE`S A SMALL CHANCE THAT LIGHT
PRECIPITATION COULD EXTEND INTO PORTIONS OF SOUTHERN CALIFORNIA AT
TIMES...MAINLY THURSDAY AND FRIDAY.
&&
.LONG TERM (SATURDAY THROUGH TUESDAY)...
THE TROUGH OF LOW PRESSURE OVER THE EASTERN PACIFIC WILL GRADUALLY
PROGRESS INLAND ACROSS CALIFORNIA DURING THE WEEKEND THROUGH EARLY
NEXT WEEK WITH MODELS STILL LACKING CONSISTENCY WITH SHORTWAVE
DETAILS. THE OVERALL PATTERN IS ONE THAT SHOULD FAVOR INCREASING
CHANCES FOR PRECIPITATION FOR SOUTHWEST CALIFORNIA WITH SOME
POTENTIAL FOR SIGNIFICANT PRECIPITATION. GREATEST AGREEMENT...SUCH
AS IT IS...IS SATURDAY/SUNDAY...WITH LESS AGREEMENT FOR TRAILING
SHORTWAVES MONDAY/TUESDAY.
&&
.AVIATION...
A WEAK EDDY HAS ALLOWED A SHALLOW 500 FT DEEP MARINE LAYER TO SPREAD
INLAND ACROSS MOST OF THE COASTAL PLAINS...RESULTING IN AREAS OF
DENSE FOG AND VERY LOW CEILINGS...WITH VISIBILITY BELOW 1/4 MILE AT
MANY COASTAL LOCATIONS. NOT MUCH DEEPENING WILL OCCUR...SO EXPECT
THE FOG TO AFFECT THE COASTAL AIRPORTS THROUGH 16Z. AN APPROACHING
TROUGH SHOULD DEEPEN THE MARINE LAYER THIS AFTERNOON. DEEPER MORE
EXTENSIVE MARINE LAYER EXPECTED EARLY EVENING LASTING WELL INTO
THURSDAY MORNING. WINDS AT 10K FT MOSTLY SW 15 TO 20 KT TODAY.
OTHERWISE GOOD VIS WITH 25K FT HIGH CIRRUS CLOUDS CONTINUING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...DENSE FOG ADVISORY UNTIL 8 AM PST THIS MORNING FOR ORANGE
COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS-SAN DIEGO
COUNTY VALLEYS.
PZ...NONE.
&&
$$
PUBLIC...MARTIN
AVIATION/MARINE...MACKECHNIE
NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 712 AM EST WED FEB 7 2007
.AVIATION...
LIGHT LAKE EFFECT SNOW SHOWERS AREA EXPECTED TO PERSIST THROUGH THE
TAF PERIOD. HOWEVER...CIGS/VSBYS ARE EXPECTED TO REMAIN MAINLY VFR.
UPSTREAM ACARS SOUNDINGS SHOW VERY LOW INVERSION HEIGHTS WITH A
RELATIVELY DRY LAYER BELOW THE INVERSION. FLOW FROM THE WNW TO THE
NW WILL HELP KEEP THE SW EDGE OF THE LAKE EFFECT BANDS CLOSE TO SBN
AND FWA.
&&
.SHORT TERM...
TODAY AND TONIGHT...ARCTIC AIR WILL CONTINUE TO SPREAD ACROSS LAKE
MICHIGAN TODAY AND TONIGHT...AND CONTINUE TO PRODUCE SOME LAKE
EFFECT SNOW SHOWERS. ALTHOUGH DELTA T VALUES CLOSE TO 20...SEVERAL
OTHER FACTORS ARE NOT THAT FAVORABLE FOR HEAVY LAKE EFFECT SNOW
SHOWERS. THESE INCLUDE LOW TO MID LEVEL SUBSIDENCE...RELATIVE LOW
INVERSION HEIGHTS...LIMITED TRAJECTORIES OVER LAKE MICHIGAN AND A
DRY AIRMASS UPSTREAM. HIGH WATER TO SNOW RATIOS SHOULD PROVIDE SNOW
ACCUMULATION UP TO AN INCH WITH ONLY UP TO 3 HUNDREDTHS OF WATER
EQUIVALENT. FOR TONIGHT...LOWERED TEMPERATURES SEVERAL DEGREES OVER
AREAS AWAY FROM LAKE MICHIGAN. ADDITIONAL SNOW ACCUMULATION OF 2 TO
5 INCHES YESTERDAY WITH SOME CLEARING SKIES TONIGHT SHOULD ALLOW
TEMPERATURES DROP CLOSE TO ZERO OVER MUCH OF THE AREA. UPSTREAM
TEMPERATURES OVERNIGHT WERE ALREADY BELOW -10F IN SOME LOCATIONS OF
NORTHERN IL. EXPECT UP TO ANOTHER INCH OF SNOW TONIGHT IN BERRIEN
AND CASS COUNTIES OF FAR SW LOWER MICHIGAN AS LAKE EFFECT SNOW
PERSISTS.
&&
.LONG TERM...
FEW CHANGES TO LONG TERM GRIDS THIS MORNING. CURRENT FORECAST
GENERALLY ON TRACK THOUGH MODEL DIFFERENCES AND INCONSISTENCIES
RAISE SOME DOUBT DURING A FEW PERIODS. GIVEN THIS UNCERTAINTY FELT
IT PRUDENT TO ALLOW GRIDS TO RIDE FOR ANOTHER RUN OR TWO.
STILL EXPECT A GRADUAL DEAMPLIFICATION TO THE OVERALL LONG WAVE
PATTERN THROUGH THE PERIOD. HOWEVER...TEMPERATURE MODERATION WILL BE
SLOW WITH GENERALLY BELOW NORMAL READINGS STILL EXPECTED RIGHT
THROUGH THIS LONG TERM PERIOD. OF SOME CONCERN IS YET ANOTHER SHORT
WAVE DIVING SOUTH OUT OF THE NORTH POLE REGION WITH CROSS POLAR FLOW
LATE THIS WEEK. AS THE LONG WAVE PATTERN DEAMPLIFIES...BULK OF COLD
AIR WITH THIS WAVE GETS SHUNTED EAST THROUGH ONTARIO AND REMAINS
WELL NORTH OF OUR AREA. CERTAINLY SOMETHING TO MONITOR AS THIS WAVE
CURRENTLY OUTSIDE OF GOOD UPPER AIR NETWORK AND THINGS COULD
CERTAINLY CHANGE GIVEN OUR RECENT PATTERN.
OTHERWISE...GENERALLY LIGHT LAKE EFFECT EXPECTED TO CONTINUE NEAR
LAKE MICHIGAN WITH DELTA T VALUES IN THE TEENS AND FLOW OFF THE
LAKE. A WAVE THURSDAY NIGHT AND FRIDAY WILL HELP TURN WINDS MORE
NORTHERLY WITH ANOTHER POSSIBLE MESO LOW TO FORM ON EASTERN SIDE OF
LAKE MICHIGAN. NAM 925MB PLUME ANALYSIS STILL INDICATES POSSIBLE
SHORE PARALLEL SINGLE BAND DEVELOPING. HOWEVER...WINDS QUICKLY BACK
DURING THE DAY FRIDAY AND THIS BAND WOULD THEN MOVE EAST AND
DISSIPATE. HOWEVER...AS WE SAW LAST WEEK...IF IT INDEED FORMS IN
ASSOCIATION WITH A MESO LOW AND VORTICITY CENTER...CERTAINLY COULD
SEE INTENSE SNOW BANDS FOR A BRIEF PERIOD. LAST NIGHT GRIDS HAD THIS
ACCOUNTED FOR BUT WERE REMOVED ON PREVIOUS SHIFT. HAVE ADDED CHANCE
POPS BACK IN FOR LAPORTE...STARKE AND NORTHERN PULASKI COUNTY. THIS
MAY BE A BIT FAR SOUTH BUT WOULD NOT BE SURPRISED TO SEE SNOW
SHOWERS THIS FAR SOUTH GIVEN THE LONG FETCH THAT WOULD BE IN PLACE.
WILL CONTINUE TO MONITOR MODEL TRENDS WITH THIS FEATURE OVER THE
NEXT FEW DAYS.
NO OTHER CHANGES TO LATER PERIODS WITH THIS PACKAGE. MAY NEED TO
EVENTUALLY ADD SNOW CHANCES FOR EARLY NEXT WEEK AS LOW DEVELOPS IN
THE SOUTHERN PLAINS AND MOVES INTO GULF COAST REGION. MODELS
CURRENTLY JUST BRUSHING OUR SOUTHERN COUNTIES BUT WE REMEMBER THE
EARLY WINTER PATTERN WHEN THE SOUTHERN STREAM LOWS LIFTED OUT WELL
NORTH OF MEDIUM RANGE PROJECTIONS. STILL PLENTY OF TIME TO MONITOR
AND ADD POPS BUT THIS SYSTEM HAS THE POTENTIAL FOR QUITE A BIT OF
QPF AND HEAVY SNOW IN THE COLD SECTOR...WHEREVER THAT SETS UP.
$$
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST THURSDAY FOR LMZ043-046.
&&
$$
AVIATION/SHORT TERM...SKIPPER
LONG TERM...LASHLY
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 307 AM EST WED FEB 7 2007
.SHORT TERM (TODAY AND TONIGHT)...
MAIN FORECAST CHALLENGE IN THE SHORT-TERM WILL BE TEMPERATURES TODAY
AND TONIGHT.
SFC LOW AND ASSOCIATED WEAK CLIPPER THAT BROUGHT OUR NERN AREAS SOME
SNOW LAST NIGHT HAS MOVED OFF TO THE SOUTHEAST AND EAST
RESPECTIVELY. MVFR CIGS ASSOCIATED WITH THE LOW ARE QUICKLY
DISSIPATING...SO WILL CLEAR OUT SKIES SOONER THAN WHAT MODELS
INDICATED.
SNOW COVER FROM YESTERDAY`S SYSTEM RANGES FROM A DUSTING ROUGHLY
FROM SALEM INDIANA TO LANCASTER KENTUCKY...TO 4 TO 5 INCHES ACROSS
THE FAR NRN BLUEGRASS...NAMELY IN BOURBON...NICHOLAS AND HARRISON
COUNTIES. THIS WILL MAKE IT DIFFICULT FOR TEMPS TO RISE
TODAY...ESPECIALLY WHERE THE SNOW DEPTHS ARE HIGHEST. THINK THAT
MOS GUIDANCE MAY BE MISSING THESE DETAILS...SO WILL LOWER TEMPS
ACROSS OUR NERN CWA FOR TODAY. THINK THAT THE HIGHS WILL BE MET
EARLY THIS MORNING FOR LOCATIONS NE OF A LINE FROM SCOTTSBURG
INDIANA TO LEXINGTON. MET GUIDANCE IS CLOSER TO BEING RIGHT I
FEEL...BUT WILL STILL UNDERCUT A FEW DEGREES. WILL LIKELY HAVE A
STEADY TEMP WORDING IN THE ZONES. SKIES SHOULD ONLY BE PARTLY
CLOUDY FOR THE MOST PART...AS SFC HIGH PRESSURE NOSES IN FROM THE
WEST. WINDS WILL BE LIGHT (5-10MPH) FROM THE NORTHWEST FOR MUCH OF
THE DAY.
FOR TONIGHT...ANOTHER FAST-MOVING SPEED MAX WILL MOVE ACROSS OUR
CWA. HOWEVER...SREF HAS NOTHING IN THE WAY OF QPF OVER US...DESPITE
GFS SHOWING SLT CHC POPS IN THE MOS OUTPUT. WILL CONTINUE DRY
FORECAST...THOUGH A FEW FLURRIES COULD CERTAINLY OCCUR. MAY INSERT
THIS INTO THE NWRN CWA AFTER 00Z. THE SPEED MAX WILL AT LEAST
INCREASE MID AND UPPER LEVEL CLOUD COVER TOWARD SUNSET...BUT THIS
PROBABLY WILL NOT BE ENOUGH TO PREVENT TEMPS FROM PLUMMETING UNDER
THE WEAK SFC HIGH. WILL AGAIN UNDERCUT GUIDANCE TONIGHT...AS
CALMING WINDS AND CONTINUED SNOW COVER WILL ALLOW TEMPS ACROSS THE
NRN BLUEGRASS TO DROP BELOW 10 DEGREES FOR OVERNIGHT LOWS.
AL
.LONG TERM (THURSDAY THROUGH TUESDAY)...
FAIRLY UNEVENTFUL FORECAST. EARLY IN THE PERIOD A DRY NORTHWEST FLOW
WILL PREVAIL. WEAK DISTURBANCES WILL ROTATE SOUTH OUT OF EASTERN
CANADA BUT PRECIPITATION WILL REMAIN WELL NORTHEAST OF THE LOWER
OHIO VALLEY. WITH THIS NORTHWEST FLOW TEMPERATURES WILL REMAIN COLD
AVERAGING SOME 10 TO 15 DEGREES BELOW NORMAL.
THE UPPER LEVEL FLOW WILL BEGIN TO FLATTEN OUT SATURDAY AS THE WEST
COAST RIDGE BREAKS DOWN. THIS WILL CREATE A SPLIT FLOW ACROSS THE
REGION. A COUPLE OF RIPPLES IN THE SOUTHERN FLOW WILL BE CAPABLE OF
PRODUCING SOME PRECIPITATION ACROSS THE FORECAST AREA. THE 00Z GFS
SHOWS SOME MOISTURE OVERSPREADING THE REGION SUNDAY BUT THE GFS
ENSEMBLE MEMBER AVERAGES KEEP THE MOISTURE SOUTH OF KENTUCKY SO
WE WILL HOLD ONTO A DRY FORECAST. A BETTER CHANCE FOR PRECIPITATION
WILL OCCUR MONDAY NIGHT AND TUESDAY AND WILL HOLD ONTO LOW POPS
FOR THAT TIME FRAME. --JA
.AVIATION (06Z TAFS)...
CURRENTLY...SFC LOW OVER SERN KY...WHERE 3.5-6KFT CIGS WERE MOVING
QUICKLY TO THE EAST. 00Z NAM12 LOW-LEVEL MOISTURE FIELDS VERIFY
CURRENT CLOUDS WELL...SO WILL FOLLOW FOR CLOUD TRENDS. A BREAK IN
THE CLOUDS CAN BE SEEN ACROSS WRN KY ATTM...HOWEVER LOW MVFR CIGS
UPSTREAM ACROSS IL/IN MAY FILTER INTO CLEAR AREAS. NAM MOVES THESE
CLOUDS SE OF THE SDF TAF SITE BY ROUGHLY 18Z...AND DISSIPATES THE
CLOUDS BY 00Z ACROSS THE LEX AND BWG TAF SITES. HOWEVER MOS
GUIDANCE IS MORE OPTIMISTIC...AND WITH SFC HIGH PRESSURE NOSING IN
FROM THE NW TODAY...WILL TREND TOWARD THE MOS GUIDANCE INSTEAD.
STRONG UPPER JET WILL FORCE CIRRUS SHIELD INTO CENTRAL KY THIS
MORNING AND AFTERNOON...SO WILL TREND FROM IFR/MVFR TO VFR CIRRUS
BY LATE MORNING AT SDF...AND ROUGHLY NOON/1PM EST AT LEX AND BWG.
A FEW FLURRIES MAY BE POSSIBLE EARLY THIS MORNING IN THE LOW
STRATO-CU...BUT SHOULD POSE NO AVIATION PROBLEMS AND WOULD LIKELY
ONLY BE AT THE LEX TAF SITE.
AS FAR AS WINDS ARE CONCERNED...THEY ARE GUSTY AND SWRLY ACROSS SRN
KY CAUSED BY A 50-70KT WLY LLJ...AND WINDS ARE LIGHT AND N/NWRLY
ACROSS SRN IN AND N-CNTRL KY...BEHIND THE SFC LOW. ANY GUSTY WINDS
WILL DISSIPATE OVER THE NEXT FEW HOURS...WITH NWRLY 6-9 KTS
RULING. WILL HOLD ONTO WIND SHEAR AT BWG FOR THE NEXT FEW HOURS
BASED OFF OF OHX ACARS SOUNDING.
AL
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 1219 AM EST WED FEB 7 2007
.AVIATION (06Z TAFS)...
CURRENTLY...SFC LOW OVER SERN KY...WHERE 3.5-6KFT CIGS WERE MOVING
QUICKLY TO THE EAST. 00Z NAM12 LOW-LEVEL MOISTURE FIELDS VERIFY
CURRENT CLOUDS WELL...SO WILL FOLLOW FOR CLOUD TRENDS. A BREAK IN
THE CLOUDS CAN BE SEEN ACROSS WRN KY ATTM...HOWEVER LOW MVFR CIGS
UPSTREAM ACROSS IL/IN MAY FILTER INTO CLEAR AREAS. NAM MOVES THESE
CLOUDS SE OF THE SDF TAF SITE BY ROUGHLY 18Z...AND DISSIPATES THE
CLOUDS BY 00Z ACROSS THE LEX AND BWG TAF SITES. HOWEVER MOS
GUIDANCE IS MORE OPTIMISTIC...AND WITH SFC HIGH PRESSURE NOSING IN
FROM THE NW TODAY...WILL TREND TOWARD THE MOS GUIDANCE INSTEAD.
STRONG UPPER JET WILL FORCE CIRRUS SHIELD INTO CENTRAL KY THIS
MORNING AND AFTERNOON...SO WILL TREND FROM IFR/MVFR TO VFR CIRRUS
BY LATE MORNING AT SDF...AND ROUGHLY NOON/1PM EST AT LEX AND BWG.
A FEW FLURRIES MAY BE POSSIBLE EARLY THIS MORNING IN THE LOW
STRATO-CU...BUT SHOULD POSE NO AVIATION PROBLEMS AND WOULD LIKELY
ONLY BE AT THE LEX TAF SITE.
AS FAR AS WINDS ARE CONCERNED...THEY ARE GUSTY AND SWRLY ACROSS SRN
KY CAUSED BY A 50-70KT WRLY LLJ...AND WINDS ARE LIGHT AND N/NWRLY
ACROSS SRN IN AND N-CNTRL KY...BEHIND THE SFC LOW. ANY GUSTY WINDS
WILL DISSIPATE OVER THE NEXT FEW HOURS...WITH NWRLY 6-9 KTS
RULING. WILL HOLD ONTO WIND SHEAR AT BWG FOR THE NEXT FEW HOURS
BASED OFF OF OHX ACARS SOUNDING.
AL
&&
.PREV DISCUSSION...
MESO UPDATE/840 PM EST...
WE WILL BE DROPPING ALL HEADLINES WITH THIS UPDATE. BULK OF
SIGNIFICANT PRECIP WILL EXIT THE LMK CWA BY 2Z/9PM EST WITH ONLY
POCKETS OF LIGHT PRECIP EXPECTED OVER OUR ERN ZONES THROUGH
MIDNIGHT. A STATEMENT CONTAINING STORM TOTAL SNOW/ICE AMOUNTS WILL
BE ISSUED THIS EVENING...UNDER THE PNSLMK IDENTIFIER...AND ALSO
POSTED TO OUR TOP-NEWS SECTION AT WEATHER.GOV/LOUISVILLE. WITH
HEADLINES BEING DROPPED...WE WILL ISSUE AN SPS FOR MUCH OF THE
NORTHERN 1/2 OF THE CWA HIGHLIGHTING SLICK SPOTS OVERNIGHT INTO THE
EARLY MORNING DRIVE TIME. WILL ALSO MENTION WIND CHILLS NEARING ZERO
BY DAYBREAK.
IMPRESSIVE TEMPERATURE CONTRAST ATTM OVER THE CWA...WITH NEAR 50F
OVER FAR SRN KY...TO THE LOWER 20S IN THE NRN BLUEGRASS. FOR THE
REMAINDER OF THE NIGHT...AS SFC LOW TRACKS EAST THROUGH THE
CWA...WINDS WILL SWITCH TO A NORTHERLY DIRECTION WITH AN AREA OF LOW
CLOUDS MOVING BACK INTO THE REGION. BANDS OF -SN CURRENTLY OVER
CNTRL/NRN IN FCST BASED ON RADAR TRAJECTORIES TO REMAIN WELL N OF
THE LMK CWA...THOUGH IF CIGS BECOME LOW ENOUGH WE COULD SEE SOME
SPOTTY -FZDZ OR FLURRIES LATE TONIGHT.
REGARDING THE EARLIER WARM SURGE ALOFT...NOTICED AN INTERESTING
OBSERVATION: PILOT REPORT NEAR HOP AT 21Z CHECKED IN WITH A SSW WIND
OF 57KTS AT 4000FT AGL. IMPRESSIVE LLJ!
UPDATED PRODUCTS SHOULD BE OUT BY 930 PM EST.
CS/MBS
SHORT TERM (TONIGHT AND WEDNESDAY)...
COMPLICATED FORECAST IN THE NEAR TERM AS TO DETERMINE WHERE SNOW
ACCUMULATION GRADIENT WILL FALL. LOOKING OVER THE PAST FEW MODEL
RUNS...IT APPEARS THAT THE NAM-WRF SOLUTION HAS BEEN A BIT MORE
CORRECT WITH THE OVERALL PLACEMENT WITH THE HEAVIEST SNOW BAND. THE
GFS IS PARTIALLY CORRECT TOO...BUT HAS BEEN OVERDOING SOME OF THE
PRECIPITATION AMOUNTS IN ITS SOLUTIONS. THE 12Z STILL HAVE SOME
DISAGREEMENT WITH THE PLACEMENT OF THE HEAVIEST SNOW BAND. WITH THE
WRF SOLUTION BEING JUST NORTH OF THE FA...WHILE THE GFS IS A BIT
MORE SOUTH. SFC LOW OVER CENTRAL MISSOURI IS FCST TO DROP INTO
WESTERN KY THIS EVENING AND THEN HEAD EAST. THE GFS SHOWS AN
ENHANCEMENT OF QPF OVER THE NE PORTION OF THE FA THIS EVENING AND
OVER IN EASTERN KY OVERNIGHT AS UPSLOPE FORCING HELPS MAINTAIN SNOW
AND SNOW SHOWERS. HAVE CHOSEN TO GO WITH A NAM-WRF COMPROMISE WHICH
WILL RESULT IN CHANGES TO THE ONGOING FCST.
FIRST...THE HEAVY SNOW WARNING STILL LOOKS GOOD FOR OUR NORTHEASTERN
COUNTIES. A TOTAL OF THREE TO SIX INCHES STILL WILL BE POSSIBLE IN
THIS AREA. HOWEVER THE BEST CHANCES OF SEEING THOSE HIGHER
ACCUMULATIONS WILL BE ACROSS NORTH OF A FRANKFORT TO PARIS LINE.
ITS A REAL TOUGH CALL IN THE LEXINGTON METRO AREA AS THE NORTHERN
PORTION OF THE COUNTY HAS RECEIVED A DECENT AMOUNT OF SNOW...WHILE
THE SOUTHERN PART OF THE COUNTY HAS NOT. THIS IS ALSO THE CASE IN
LOUISVILLE WHERE WE HAVE DUSTING HERE...BUT JUST OUTSIDE THE COUNTY
WE HAVE 1/2 TO 1 INCH REPORTS ACROSS OLDHAM COUNTY.
A SHARP GRADIENT OF SNOW ACCUMULATION IS LIKELY AND PORTIONS OF THE
COUNTIES IN THE WARNING AREA MAY HIT THE CRITERIA...WHILE OTHER
PORTIONS DO NOT. FURTHER SOUTH AND WEST...WE PLAN ON TRIMMING BACK
THE SNOW ADVISORY. PLAN ON RUNNING THIS FROM WASHINGTON COUNTY
INDIANA THROUGH LOUISVILLE METRO AND DOWN TO GARRARD COUNTY. IN
THIS AREA...A GENERAL 1 TO 3 INCHES OF ACCUMULATION WILL BE
POSSIBLE. UPSTREAM RADAR SHOWS ANOTHER BATCH OF SNOW SHOWERS COMING
INTO OUR NORTHWEST PORTIONS WHICH WILL HIT THIS ADVISORY AREA LATER
THIS EVENING. ACROSS THE SOUTHWEST...MAINLY DRY CONDITIONS ARE
EXPECTED TONIGHT. IN THE FAR SOUTHEAST...SOME PRECIPITATION MAY
LINGER DOWN CLOSE THE SOMERSET AREA WHERE P-TYPE WILL BE A MIX OF
RAIN/FZRA/PL/SNOW. AM NOT CONFIDENT ON AMOUNTS OR COVERAGE...BUT
WILL KEEP A CHC IN. ACCUMULATIONS IN THIS AREA WOULD BE LITTLE OR
NONE.
SNOW WILL EXIT THE REGION LATER TONIGHT FROM NORTHWEST TO
SOUTHEAST...SO WILL LEAVE CURRENT ADVISORY/WARNING ENDING TIMES AS
IS AND LET FUTURE SHIFTS TRIM BACK AS NECESSARY. TEMPERATURES IN
THE SNOW COVERED AREAS WILL DROP OFF INTO THE TEENS LATER TONIGHT
WITH LOWER TO MID 20S DOWN ACROSS THE SOUTH. MOSTLY CLOUDY SKIES
WILL START OFF THE DAY ON WEDNESDAY WITH SOME CLEARING NOTED IN THE
AFTERNOON. NORTH WINDS WILL KEEP TEMPERATURES BELOW NORMAL ONCE
AGAIN...ESPECIALLY IN AREAS THAT HAVE SNOW PACK. IN GENERAL HAVE
GONE CLOSER TO 2M RAW MODEL OUTPUT FOR THIS FORECAST PERIOD.
THANKS TO JKL/IND/PAH AND LEX MEDIA FOR COORDINATION THIS AFTERNOON.
-MJ
LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)...
THE VERY COLD ARCTIC AIR MASS HAS SHIFTED OFF TO THE NORTHEAST...BUT
SYSTEMS ROTATING SOUTHEAST ACROSS THE NORTH CENTRAL U.S. AROUND THE
COLD VORTEX OVER EAST CENTRAL CANADA WILL KEEP SOME COLD ARCTIC AIR
FLOWING ACROSS THE REGION DURING THE NEXT FEW DAYS...BUT THIS AIR IS
RELATIVELY DRY SO NO REALLY GOOD PRECIPITATION CHANCES FOR THE NEXT
FEW DAYS. MAX AND MIN TEMPS SHOULD AVERAGE SOME 10 TO 15 DEG BELOW
THE SEASONAL NORMALS FOR THIS TIME OF YEAR.
BY THE WEEKEND AND INTO THE NEXT WORKWEEK A SERIES OF PACIFIC
TROUGHS OFF THE WEST COAST OF THE U.S. WILL EVENTUALLY ESTABLISH
MORE OF A SPLIT FLOW PATTERN. THIS NEW SOUTHERN STREAM WILL LIKELY
SET UP EAST TO WEST ACROSS THE SOUTH CENTRAL U.S. GIVEN THAT THE
THE COLD AIR WILL STILL BE IN PLACE ACROSS THE REGION DUE TO THE
NORTHERN STREAM...THIS SCENARIO COULD EVENTUALLY EVOLVE INTO ONE OR
MORE RAIN/SNOW PRODUCING STORM SYSTEMS LATE IN THE PERIOD AND BEYOND.
ONE SUCH STORM SYSTEM IS FORECAST BY THE GFS AND THE LATEST HPC
EXTENDED GUIDANCE PICKS UP ON THIS TOO. THIS LOOKS OK TO US TOO.
WE WILL INTRODUCE A CHANCE OF LIGHT SNOW ON MONDAY NIGHT AND A CHANCE
FOR A RAIN OR SNOW MIX ON TUESDAY. --21
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$