FXUS63 KLOT 062328
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
528 PM CST SUN DEC 6 2009
.DISCUSSION...
240 PM CST
CURRENT WATER VAPOR IMAGERY SHOW SHORT WAVE LIFTING NEWD ACROSS
KS/ERN OK. SOME ENHANCED CLOUD TOPS OVR MO VLY IN ASSN WITH THIS
DISTURBANCE ARE PRODUCING AN AREA OF LGT SNOW. THIS FEATURE IS
FCST TO TO CONTINUE NEWD...TO EXTEND FROM ERN IA-CNTRL IL BY 12Z
MON. THEREFORE...WILL GO WITH LIKELY POPS FOR LIGHT
SNOW...ESPECIALLY OVR FAR NRN/NWRN PORTION OF FA WHERE WEAK
COLD FRONT IS FCST TO BE LOCATED AS DAMPENING SHORT WAVE MOVES
THROUGH. NOT A LOT OF MOISTURE FOR THIS SYS TO WORK WITH...AND
GIVEN SCANT QPF...DON'T SEE MUCH MORE THAN AN INCH
ACCUMULATION...GENERALLY N OF I-88. REMAINDER OF AREA WILL
PROBABLY SEE A PERIOD OF LIGHT SNOW AS WELL...HOWEVER...IN
SOMEWHAT MILDER AIR AHEAD OF WEAK BOUNDARY...MUCH OF THIS MAY NOT
REACH THE GROUND AND AM LOOKING AT ANY ACCUMULATION BEING VERY
MINOR.
THIS SYS ZIPS OFF TO THE E BY NOON MONDAY AS IT CONTINUES TO SHEAR
OUT. IN ITS WAKE...SOME WEAK LLVL COLD ADVECTION WILL ALLOW FOR
MINOR REINFORCEMENT OF COLD AIR OVER REGION MONDAY NIGHT.
MOST ATTENTION...OF COURSE...HAS ONCE AGAIN BEEN FOCUSED ON BIG
HULLABALOO EXPECTED TO ARRIVE LATE TUESDAY-TUESDAY EVENING. MODELS
SEEM TO BE ZEROING IN ON A TRACK THAT WILL BRING SFC LOW JUST SE
OF CHICAGO BY 12Z WED. EXPANSIVE AREA OF WARM ADVECTION PRECIP
WILL LIKELY DVLP AHEAD OF THIS SYS TUESDAY AFTN-EVENING...WITH
STRONGEST ISENTROPIC UPGLIDE AND MOISTURE ADVECTION TAKING PLACE
TUESDAY EVENING. EXPECT THAT PRECIP WILL STAY MAINLY SNOW AS THIS
AREA OF PRECIP LIFTS NWD ACROSS AREA TUESDAY EVENING. ONCE THIS
DYNAMIC COOLING OF COLUMN RELAXES...FCST SOUNDINGS GENERALLY PUMP
ENOUGH WARM AIR ACROSS AREA TO CHG PRECIP TO RAIN/DRIZZLE ALONG
AND E OF I-55. FROM FOX RIVER WWD...PRECIP LOOKS MORE LIKELY TO
REMAIN MOSTLY SNOW. GIVEN HIGH QPF FROM MODELS AS WELL AS HPC
GUIDANCE...FEEL CONFIDENT IN HEADLINING A WINTER STORM WATCH FOR
THESE AREAS. FCST OF PRECIP TYPE AND AMOUNT IS HIGHLY PROBLEMATIC
AT THIS POINT. GIVEN STRENGTH OF WAA PRECIP TUESDAY
EVENING...SEVERAL INCHES OF SNOW COULD PILE UP EVEN E OF WATCH
AREA BEFORE PRECIP CHANGES TO LIQUID AND DIMINISHES AS BETTER
FORCING LIFTS TO N AND E. OF NOTE IS THAT MODELS SEEM TO WANT TO
KEEP THIS SYSTEM AN OPEN WAVE CYCLONE...RATHER THAN DEEPENING IT
INTO A CLOSED SYSTEM. THIS LENDS SUPPORT TO KEEPING THE SFC/LLVL
CIRCULATION ON A GENERAL NELY COURSE...RATHER THAN HAVING IT BCM
VERTICALLY STACKED...CURLING IT ANY FURTHER TO LEFT /WEST/. BASED
ON THIS...HAVE A LITTLE MORE CONFIDENCE IN MODEL CONSENSUS
REGARDING TRACK OF LOW.
SOME WRAP AROUND SNOW/SNOW SHOWERS ON WED...BUT MAIN CONCERN BY
THAT TIME WILL BE WIND AND FALLING TEMPS. HAVE KEPT WINTER STORM
WATCH VALID THROUGH THE DAY WEDNESDAY AS BLOWING SNOW MAY BE QUITE
SIGNIFICANT...PARTICULARLY ACROSS AREAS RECEIVING MAINLY SNOW
THROUGH THE EVENT.
REGARDLESS OF WHAT HAPPENS WITH TUESDAY NIGHTS STORM...COLDEST AIR
THUS FAR THIS SEASON APPEARS HEADED FOR MIDWEST. WILL GO WITH LOWS
NEAR ZERO LATTER PORTION OF WEEK FOR THOSE AREAS EXPECTED TO BE
SNOW COVERED...WITH MINS IN 10-15 RANGE OVR AREAS FCST TO RETAIN
BARE GROUND.
MERZLOCK
&&
.AVIATION...
0000 UTC TAFS...
LITTLE CHANGE THIS EVENING TO GOING FORECAST...WITH CIGS AND VIS
WITH EARLY MORNING SNOW CONTINUING TO BE THE PRIMARY FOCUS.
BROAD AREA OF LOW PRESSURE CURRENTLY NEAR THE OKLAHOMA/TEXAS
BORDER IS EXPECTED TO LIFT NORTHEAST ALONG A STATIONARY FRONTAL BOUNDARY LATE
TONIGHT AND EARLY TOMORROW MORNING AS IT BECOMES BETTER ORGANIZED.
AS THIS LOW LIFTS NORTH LATE TONIGHT...EXPECT LIGHT SNOW TO BEGIN
NEAR RFD/WISCONSIN STATE LINE AND THEN DEVELOP SOUTHEAST TOWARD
OTHER TERMINALS. RIGHT NOW...LOOKS AS IF BEST SNOW WILL BE JUST TO
THE NORTH OF THE SURFACE LOW AND NEAR THE AFOREMENTIONED SURFACE
BOUNDARY. AS SUCH...EARLIEST AND HEAVIEST SNOWS TO BE AT
RFD...WITH LESSENING AMOUNTS SOUTH. HAVE MAINTAINED AN HOUR OF
HIGH-END IFR VIS AT RFD...AND KEPT CIGS AND VIS IN LOW END MVFR
RANGE ELSEWHERE. CERTAINLY COULDN'T RULE OUT A PERIOD OF IFR VIS
AT ORD/MDW/DPA IF A BAND OF HEAVIER SNOW MAKES IT FAR ENOUGH
SOUTH...BUT CONFIDENCE AT THIS POINT ISN'T HIGH ENOUGH TO INCLUDE
IN 00Z TAFS.
BY LATE MORNING MONDAY...SNOW IS EXPECTED TO END ACROSS THE
TERMINALS AS THE LOW LIFTS AWAY FROM THE AREA. AS THIS LOW LIFTS
NORTHEAST...IT WILL DRAG THE SURFACE FRONT SOUTHEAST ACROSS THE
TERMINALS...RESULTING IN WINDS SHIFTING FROM SOUTH/SOUTHWEST TO
THE WEST AND EVENTUALLY NORTHWEST BY LATE TOMORROW AFTERNOON.
BOXELL
&&
.MARINE...
150 PM...HIGH END GALE FORCE WINDS LIKELY WEDNESDAY AND WEDNESDAY
NIGHT. GALE WATCH WILL BE ISSUED FOR THE OPEN WATERS.
MAIN FORECAST CONCERN/CHALLENGE REMAINS A MAJOR WINTER STORM TO
MOVE ACROSS THE LAKES REGION TUESDAY NIGHT INTO WEDNESDAY.
IN THE SHORT TERM...A WEAK COLD FRONT CURRENTLY EXTENDING FROM
CENTRAL LAKE MICHIGAN SOUTHWEST INTO MISSOURI WILL REMAIN NEARLY
STATIONARY TONIGHT...AS AN AREA OF WEAK LOW PRESSURE LIFTS
NORTHEAST ALONG THE FRONT LATER TONIGHT AND MONDAY MORNING. THIS
LOW WILL QUICKLY MOVE NORTHEAST MONDAY AFTERNOON...WITH THE COLD
FRONT MOVING SOUTHEAST OF THE LAKE BY LATE MONDAY AFTERNOON.
WINDS WILL THEN TURN NORTHWEST AND INCREASE A BIT TO 15-20 KTS FOR
A SHORT TIME MONDAY EVENING. WINDS WILL DIMINISH OVERNIGHT INTO
EARLY TUESDAY MORNING AS A RIDGE OF HIGH PRESSURE MOVES ACROSS
THE NORTHERN LAKES.
THIS RIDGE WILL QUICKLY MOVE NORTHEAST AS A STRONG AREA OF LOW
PRESSURE OVER THE SOUTHERN PLAINS BEGINS TO MOVE NORTHEAST...
REACHING NORTHWEST INDIANA BY WEDNESDAY MORNING...AS IT DEEPENS.
CURRENT MODEL TRENDS SUGGEST THIS LOW MAY DEEPEN TO AS LOW AS 29.0
INCHES BY THIS TIME THEN CONTINUE TO DEEPEN FURTHER TO 28.8 INCHES
AS IT MOVES ACROSS LAKE HURON WEDNESDAY EVENING. STRONG COLD AIR
POURING ACROSS THE WESTERN LAKES COMBINED WITH AN EXTREMELY TIGHT
PRESSURE GRADIENT SHOULD EASILY PRODUCE GALES TO 45 KTS OVER
SOUTHERN LAKE MICHIGAN BY WEDNESDAY EVENING. A 3 TO 6 HR PERIOD OF
STORM FORCE WIND GUSTS TO 50 KTS IS CERTAINLY POSSIBLE WEDNESDAY
EVENING. HOWEVER...WILL MAINTAIN GALES TO 45 KTS FOR NOW WITH
PLENTY OF TIME TO UPGRADE TO STORM FORCE IF CURRENT TRENDS
CONTINUE.
WITH HIGH PRESSURE BUILDING SOUTHEAST ACROSS THE CENTRAL PLAINS
WEDNESDAY NIGHT INTO THURSDAY...COMBINED WITH A STILL STRONG LOW
PRESSURE MOVING ACROSS QUEBEC...SUSPECT A PROLONGED PERIOD OF
GALES TO 35-40KTS WILL LIKELY CONTINUE INTO THURSDAY EVENING
BEFORE FINALLY DIMINISHING UNDER 30KTS BY FRIDAY MORNING. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011-
ILZ012-ILZ019...6 PM TUESDAY TO 7 PM WEDNESDAY.
IN...NONE.
LM...GALE WATCH...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878...NOON WEDNESDAY TO 9 PM THURSDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ868...9 PM WEDNESDAY TO 9 PM THURSDAY.
&&
$$
