FXUS63 KLOT 050443
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1043 PM CST FRI DEC 4 2009
.DISCUSSION...
309 PM...SHORT TERM FORECAST CONCERNS ARE FLURRIES/SNOW SHOWERS
THIS EVENING ALONG WITH LOW TEMPS TONIGHT. LONGER TERM CONCERNS
ARE LIGHT SNOW/MINOR ACCUMULATIONS SUNDAY NIGHT/MONDAY MORNING
AND THEN WHAT MAY BE THE FIRST WINTER STORM OF THE SEASON FOR THE
AREA TUESDAY NIGHT INTO WEDNESDAY.
AS EXPECTED...TEMPS HAVE STRUGGLED TO REACH THE UPPER 20S TODAY
WITH SOME LOCATIONS ONLY IN THE MID 20S. CLOUDS HAVE SCATTERED OUT
OVER PARTS OF THE AREA BUT STILL BKN/OVC STRATOCU UPSTREAM ALONG
WITH FLURRIES/SNOW SHOWERS. HOWEVER...AS THE UPPER TROF CONTINUES
TO LIFT NORTH THIS EVENING...EXPECT CLOUDS TO GRADUALLY SCATTER
OUT AND ANY PRECIP TO DIMINISH. SO HAVE INCLUDED FLURRIES FOR THIS
EVENING WITH DECREASING CLOUDS OVERNIGHT. TEMPS MIGHT BE SLOW TO
FALL THIS EVENING DEPENDING ON CLOUD COVER BUT BY MORNING...AS
WINDS DIMINISH...EXPECT LOWS AWAY FROM DOWNTOWN CHICAGO TO DROP
WELL INTO THE TEENS.
TEMPS MODERATE SOME SATURDAY AS FLOW TURNS SOUTHERLY. MAV TEMPS
LOOK A LITTLE TOO WARM...GIVEN COLD MORNING LOWS. SO TRENDED
TOWARD THE COOLER MET. TEMPS WARM A FEW MORE DEGREES INTO THE
UPPER 30S ON SUNDAY...BUT TIMING DIFFERENCES WITH THE NEXT
SYSTEM/WEAK COLD FRONT MAY AFFECT TEMPS BY AFTERNOON. TIMING/
LOCATION DIFFERENCES AMONG THE MODELS WITH THE COLD FRONT MOVING
SOUTH ACROSS THE AREA SUNDAY NIGHT INTO MONDAY MORNING...WITH A
WEAK LOW EVENTUALLY DEVELOPING ALONG THE FRONT. DESPITE
DIFFERENCES...STILL APPEARS AN AREA OF LIGHT SNOW WILL DEVELOP
ACROSS THE AREA SUNDAY NIGHT AND CONTINUE INTO MONDAY MORNING...
LIKELY ENDING BY MIDDAY MONDAY. CURRENTLY HAVE BETWEEN 0.10 AND
0.15 QPF IN THE GRIDS SO AN INCH OR TWO LOOKS POSSIBLE. WHILE THIS
IS EXPECTED TO BE A MINOR EVENT...COULD BE OCCURRING JUST BEFORE
AND/OR DURING MONDAY MORNING/S RUSH HR.
SHORT BREAK BETWEEN SYSTEMS MONDAY NIGHT INTO TUESDAY WITH THE
NEXT AND MUCH STRONGER STORM SYSTEM TO MOVE ACROSS THE REGION MID
WEEK. CONFIDENCE CONTINUES TO INCREASE THAT THERE WILL BE PRECIP
THUS HAVE BUMPED POPS UP TO LIKELY BUT CONFIDENCE REGARDING PRECIP
TYPE REMAINS LOW. PREVIOUS MODEL RUNS HAD PROGGED A SFC LOW TO
RAPIDLY DEEPEN OVER THE LAKES LATE TUESDAY NIGHT INTO WEDNESDAY.
CURRENT RUNS CONTINUE THIS TREND...THOUGH NOT QUITE AS DEEP AS
PREVIOUS RUNS. PRECIP TYPE OBVIOUSLY DEPENDENT ON THE TRACK OF THE
LOW AND WHILE A MIX OF SLEET/FREEZING RAIN IS POSSIBLE...IT COULD
BE RATHER BRIEF. BUT FROM THIS DISTANCE...ITS NEXT TO IMPOSSIBLE
TO GET TOO SPECIFIC. HAVE OPTED TO MAINTAIN SNOW ACROSS MOST OF
THE CWA WITH A RAIN/SNOW MIX ACROSS THE SOUTHEAST CWA...PRIMARILY
BECAUSE IN THIS AREA...PRECIP MAY END UP BEING EITHER ALL RAIN OR
ALL SNOW. STORM TOTAL QPF OFF THE MODELS DURING THIS TIME PERIOD
RANGE FROM A HALF INCH TO AN INCH LIQUID SO IF...AND THATS A BIG
IF...THAT VERIFIES AND FALLS AS SNOW...THIS WILL BE A SIGNIFICANT
WINTER STORM. AT THIS POINT WILL JUST CONTINUE WITH CURRENT
WORDING IN THE UPDATED HWO THIS MORNING OF AN ACCUMULATING SNOW.
IN ADDITION TO THE PRECIP...DEPENDING ON THE STRENGTHEN OF THE
LOW...WINDS WILL LIKELY BE GUSTING 30-35 MPH FOR TIME WEDNESDAY
AFTERNOON INTO WEDNESDAY EVENING. WINDS APPEAR TO DIMINISH RATHER
QUICKLY WEDNESDAY NIGHT HOWEVER...AS A RIDGE OF HIGH PRESSURE
BUILDS ACROSS THE AREA BY THURSDAY MORNING.
AFTER THIS STORM PASSES AND ESPECIALLY IF THE AREA GETS SEVERAL
INCHES OF SNOW...TEMPS WILL LIKELY PLUNGE INTO THE SINGLE DIGITS
BY THURSDAY MORNING. HAVE NOT GONE THAT LOW YET...BUT IT SHOULD BE
NOTED THAT THE 12Z MEX GUIDANCE IS 8-12 DEGREES BELOW CLIMO FOR
DAYS 6 AND 7 AND THIS IS RATHER IMPRESSIVE SINCE THE MEX GUIDANCE
IS WEIGHTED MORE TOWARD CLIMO AT THAT DISTANCE. SO HAVE GONE BELOW
MEX FOR LOWS AND THIS MAY STILL END UP BEING TOO WARM. HIGHS NEXT
THURSDAY ALSO POSSIBLY TOO WARM. PROGRESSIVE PATTERN CONTINUES
THRU NEXT WEEKEND WITH ANOTHER CHANCE OF SNOW...AND MODERATING
TEMPS...NEXT FRIDAY. CMS
&&
.AVIATION...
0600 UTC TAFS...
GENERALLY QUIET WEATHER TO CONTINUE DURING THIS TAF CYCLE.
UPPER TROUGH JUST NORTH OF LAKE SUPERIOR CONTINUES TO PULL OFF TO
THE NORTHEAST TONIGHT. EMBEDDED WEAK SHORTWAVE ROTATING SOUTH
ALONG THE WESTERN EDGE OF THIS TROUGH LOOKS TO MAKE JUST A
GLANCING BLOW TO THE AREA...AS A RESULT EXPECT CIGS TO REMAIN VFR
THROUGH THE OVERNIGHT. ALSO EXPECT PERIODS OF VERY LIGHT
SNOW/FLURRIES TO CONTINUE UNTIL MORNING.
BY DAYBREAK SATURDAY...HEIGHTS ALOFT ARE EXPECTED TO BE ON THE
RISE AS HIGH PRESSURE NOSES NORTH ACORSS THE MID MISSISSIPPI
VALLEY. FORECAST SOUDINGS SUGGEST THE POSSIBILITY OF JUST A FEW
VFR STRATOCU DURING THE DAY. WINDS ON SATURDAY ARE EXPECTED TURN A
BIT MORE TO THE SOUTH...AND MAY GUST INTO THE MID TO UPPER TEENS
BY AFTERNOON. WINDS SHOULD SUBSIDE SHORTLY AFTER SUNDOWN...WITH
JUST SOME SCT CI BLOWING IN ACROSS THE AREA ON AN APPROACHING
UPPER JET.
BOXELL
&&
.MARINE...
1229 PM CST
LIGHT TO MODERATE WEST TO SOUTHWEST WINDS EXPECTED THROUGH THE
WEEKEND BEFORE A FRONTAL PASSAGE SUNDAY NIGHT OR MONDAY. A SHIFT
TO MODERATE NORTHWEST WINDS IS EXPECTED BEHIND THE FRONT BUT WINDS
SHOULDNT GET TOO OUT OF HAND GIVEN LACK OF ANY STRONG HIGH
BUILDING IN. BY FAR THE BIGGEST MARINE STORY IS THE POWERFUL STORM
MEDIUM RANGE MODELS MOVE ACROSS THE GREAT LAKES REGION THE MIDDLE
OF NEXT WEEK. GIVEN RELATIVELY GOOD MODEL AGREEMENT ON A FAST
MOVING 29.0 INCH OR DEEPER LOW MOVING ACROSS THE WESTERN LAKES
FELT COMFORTABLE INTRODUCING GALES INTO THE FORECAST NEXT
WEDNESDAY.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
