FXUS61 KILN 071125
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
625 AM EST MON DEC 7 2009
.SYNOPSIS...
A FAST MOVING UPPER LEVEL WEATHER DISTURBANCE WILL TRACK ACROSS
THE GREAT LAKES TODAY. HIGH PRESSURE WILL BRIEFLY BUILD INTO THE
OHIO VALLEY TONIGHT. A STRONG STORM SYSTEM WILL MOVE FROM THE
SOUTHERN PLAINS TO THE GREAT LAKES REGION LATE TUESDAY INTO
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
HAVE RELIED ON THE RUC MODEL FOR THE FORECAST FOR TODAY.
A FAST MOVING SHORT WAVE WILL LIFT ACROSS THE REGION THIS MORNING.
THIS SYSTEM WILL BE SHEARING AND WEAKENING WITH TIME AS IT TRACKS
INTO THE GREAT LAKES BY THE AFTN HOURS. HOWEVER...THERE WILL BE
ENOUGH LOW LEVEL FORCING AND ISENTROPIC LIFT TO PRODUCE SOME LIGHT
SNOW. SOME OF THE SNOW MAY MIX WITH A LITTLE RAIN ALONG AND SOUTH
OF THE OHIO RIVER THIS MORNING. SINCE THE SYSTEM IS MOVING QUICKLY
AND WEAKENING...AM ONLY EXPECTING LESS THAN AN INCH OF SNOW
ACCUMULATION FOR THE ENTIRE FORECAST AREA. THIS WILL BE THE FIRST
ACCUMULATING SNOW FOR MOST OF THE REGION AND IT WILL BE COMING
DURING THE PEAK MORNING RUSH HOUR. GIVEN THAT SFC TEMPS ARE
GENERALLY BELOW FREEZING...A LITTLE BIT OF SNOW MAY CAUSE SOME
SLICK SPOTS TO DEVELOP. WILL HIGHLIGHT THIS THREAT WITH SPECIAL
WEATHER STATEMENTS. OTHERWISE...PCPN SHOULD PRETTY MUCH COME TO AN
END BY AFTN. HIGHS WILL RANGE FROM THE MID 30S NW TO THE LOWER 40S
SOUTHEAST.
FOR TONIGHT...WEAK HIGH PRESSURE WILL BUILD BRIEFLY ACROSS THE
OHIO VALLEY. MOSTLY CLOUDY SKIES WILL BECOME PARTLY CLOUDY. LOWS
WILL RANGE FROM THE MID 20S NORTH TO THE LOWER 30S SOUTH.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
MODELS ARE IN FAIRLY DECENT AGREEMENT IN TERMS OF SYNOPTIC SCALE
SYSTEMS FOR THE SHORT TERM FORECAST. HAVE TAKEN A BLEND OF THE
GFS/ECMWF.
LOW PRESSURE WILL DEEPEN AS IT TRACKS FROM THE SOUTHERN PLAINS TO
THE WESTERN GREAT LAKES TUESDAY NIGHT INTO WEDNESDAY MORNING.
THIS LOW WILL BE ASSOCIATED WITH A NEGATIVELY TILTED S/WV WHICH
DENOTES A STRONG SYSTEM. MODELS NOW INDICATE THAT STRONG MOIST...
WAA/ISENTROPIC LIFT WILL SPREAD PCPN FROM SW TO NE DURING THE DAY
TUESDAY...MUCH FASTER THAN PREVIOUSLY THOUGHT. THIS WILL CAUSE A
PCPN TYPE ISSUE AS LOW LEVELS WILL START OUT DRY AND COLD. AT THIS
TIME...IT APPEARS THAT PERHAPS A LITTLE SLEET MAY MIX IN WITH RAIN
ALONG AND SOUTH OF I-70 TUESDAY AFTN BEFORE QUICKLY CHANGING TO
ALL RAIN. NORTH OF I-70...THERE COULD BE A MIXTURE OF SNOW...SLEET
AND RAIN. HAVE NOT INDICATED FREEZING RAIN ATTM AS SFC TEMPS
SHOULD BE ABOVE FREEZING. WILL HAVE TO MONITOR...HOWEVER ...SHOULD
EVAPORATIVE COOLING AND AN EASTERLY WIND ALLOW TEMPERATURES TO DIP
TO NEAR FREEZING TUESDAY AFTN AND EARLY EVENING. GIVEN MUCH
UNCERTAINTY AT THIS TIME AND WITH TEMPS ABOVE FREEZING...WILL NOT
FORECAST MUCH IN THE WAY OF SNOW/SLEET ACCUMULATION.
WITH A STRONG LOW LEVEL JET AND SFC WAA...RAIN WILL ENCOMPASS THE
ENTIRE AREA TUESDAY NIGHT OUT AHEAD OF AN APPROACHING COLD FRONT.
THE WEATHER WILL GET INTERESTING ON WEDNESDAY AS AFOREMENTIONED LOW
CONTINUES TO DEEPEN AS IT MOVES FROM NEAR NE ILLINOIS TO LAKE
HURON BY WEDNESDAY EVENING. THIS WILL SEND A STRONG COLD FRONT
ACROSS OUR AREA DURING THE MORNING HOURS. HIGHS WILL OCCUR EARLY
WITH TEMPERATURES FALLING DURING THE AFTN. RAIN/SHOWERS WILL
TRANSITION OVER TO SNOW SHOWERS DURING THE AFTN WITH LITTLE SNOW
ACCUMULATION EXPECTED. THE BIG PROBLEM FOR WEDNESDAY/WEDNESDAY
NIGHT WILL BE HOW STRONG THE WINDS BECOME. A TIGHTENING SFC
PRESSURE GRADIENT...STRONG WINDS ALOFT AND STRONG CAA WILL BRING
WIND GUSTS IN THE 40 TO 50 MPH RANGE. SO....AT THIS TIME...IT
APPEARS THAT A WIND ADVISORY WILL BE NEEDED AT SOME POINT. WILL
HAVE TO MONITOR LATER FORECASTS SHOULD A HIGH WIND WATCH OR
WARNING BE NEEDED...ESPECIALLY FOR WINDS JUST BEHIND THE COLD
FRONTAL PASSAGE.
SNOW SHOWERS WILL TAPER OFF WEDNESDAY NIGHT AS THE STORM SYSTEM
MOVES NE OF THE REGION. MUCH COLDER AIR WILL SPILL INTO OUR AREA
FOR THE REMAINDER OF THE WEEK.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A BROAD UPPER LEVEL TROUGH WILL REMAIN IN PLACE ACROSS THE EASTERN
HALF OF THE UNITED STATES THROUGH NEXT WEEKEND. THIS WILL LEAD TO
A CONTINUATION OF BELOW NORMAL TEMPERATURES. HAVE TRENDED TEMPS
COOLER THAN GUIDANCE...ESPECIALLY THURSDAY INTO FRIDAY AS SURFACE
HIGH PUSHES EAST INTO OUR AREA. THE 12Z ECMWF IS FARTHER NORTH
THAN THE GFS WITH SOUTHERN SYSTEM LATE IN THE PERIOD. HAVE OPTED
TO KEEP THE FORECAST DRY AT THIS POINT FOR THE WEEKEND...BUT IF
MODELS CONTINUE TO TREND NORTH...WE MAY EVENTUALLY NEED TO
INTRODUCE SOME PCPN ACROSS AT LEAST THE SOUTH FOR SATURDAY INTO
SUNDAY.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
LARGE AREA OF MAINLY LIGHT SNOW CONTINUES TO SHIFT ACROSS THE TAF
SITES AS WE SPEAK...AS SHORTWAVE TROUGH SLIDES NORTHEAST ACROSS
THE GREAT LAKES. RADAR HAS BEEN PRETTY FULL OF ECHO ALL NIGHT LONG
BUT MUCH OF THE RETURN GETTING SUBLIMED IN THE DRIER LAYERS BELOW
2KM. SNOW HAS ONLY RECENTLY BEEN HITTING THE GROUND AT CVG/ILN/DAY
WITH POCKETS OF IFR VSBY AMIDST MORE GENERAL MVFR/VFR SNOWS.
FORCING FOR ASCENT TIED TO 850-700MB MOISTURE TRANSPORT AXIS WITH
BULK OF SNOW SITUATED IN CONVERGENCE AREA OF THIS STREAM OF
MOISTURE/THETA-E ADVECTION. THIS FORECAST PER 07.09Z RUC TO SHIFT
RAPIDLY EAST TODAY WHICH MEANS A QUICK END TO MOST OF THE SNOW BY
15Z. ACCUMULATIONS SHOULD REMAIN A HALF INCH OR LESS...PRETTY HIGH
CONFIDENCE IN THAT. MAY SEE SOME MVFR CIGS LINGER FOR A WHILE
INTO THE AFTERNOON IN THE WAKE OF THE SNOW...BUT LARGER SCALE WEAK
SUBSIDENCE AND 07.06Z NAM-WRF SOUNDINGS SUGGEST CLEARING WILL TAKE
PLACE EITHER LATE THIS AFTERNOON OR EARLY THIS EVENING...WITH
PERIOD OF QUIET WEATHER TONIGHT INTO TUESDAY MORNING. WINDS TO GO
LIGHT OVERNIGHT TONIGHT BUT TURN EASTERLY AND BEGIN TO STRENGTHEN
AS INTENSE MID- CONUS STORM REVVS UP.
OUTLOOK...WIDESPREAD PRECIPITATION WITH MVFR/IFR CIGS/VSBYS AND
GUSTY WINDS ARE LIKELY TUESDAY AFTERNOON THROUGH WEDNESDAY.
MVFR CIGS ARE POSSIBLE WEDNESDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...HICKMAN
SHORT TERM...HICKMAN
LONG TERM...JGL
AVIATION...BINAU
