Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 251739
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST TUE NOV 25 2014

.SHORT TERM...
303 AM CST

THROUGH WEDNESDAY...

PRIMARY FORECAST CHALLENGE TODAY IS CLOUD COVER. GUIDANCE IS ALL
FAIRLY AGGRESSIVE IS CLEARING THINGS OUT THIS AFTERNOON SAVE FOR THE
WRF-NAM. MODELS ARE OFTEN TOO QUICK TO CLEAR STRATUS OUT IN THE
WINTER...THOUGH IN THIS CASE IT IS A FAIRLY TRANSIENT PATTERN SO
STRATUS MAY BE A BIT QUICKER TO CLEAR THAN IS TYPICAL. MOS GUIDANCE
KEEPS SKIES FAIRLY CLOUDY AND HAVE MAINTAINED CLOUDINESS LONGER THAN
GUIDANCE SUGGESTS BUT DO PARTIALLY CLEAR SKIES OUT TONIGHT FOR A
TIME BEFORE CLOUDS ROLL BACK IN AHEAD OF THE NEXT SYSTEM.

SPEAKING OF THE NEXT SYSTEM...GUIDANCE CONTINUES TO TAKE THE CLIPPER
ON THE SOUTHERN ROUTE WITH ITS PRECIP LARGELY MISSING OUR CWA. HAVE
MAINTAINED SOME SLIGHT CHANCE POPS IN OUR SOUTHWESTERN MOST CWA
WEDNESDAY BUT OTHERWISE CONTINUED THE TREND FROM THE DAY SHIFT OF
LOWERING POPS...COMPLETELY REMOVING THEM FROM MUCH OF THE CWA.

IZZI

&&

.LONG TERM...
303 AM CST

WEDNESDAY NIGHT ONWARD...

IN THE LONGER TERM GUIDANCE IS STILL BRINGS IN A TRANSIENT BUT
MODERATELY POTENT SHOT OF COLD AIR THANKSGIVING DAY WHEN HIGHS
SHOULD ONCE AGAIN HOLD IN THE 20S. LARGE SCALE PATTERN WILL BEGIN TO
TRANSITION TO MORE OF A ZONAL FLOW BY FRIDAY WITH WARM AIR ADVECTION
BEGINNING AND POSSIBLY PRODUCING A BIT OF LIGHT PRECIP...BUT IF
ANYTHING DOES FALL AMOUNTS LOOK TO BE VERY LIGHT. BY SATURDAY STRONG
LOW PRESSURE IS PROGGED TO TRACK EAST INTO THE UPPER GREAT LAKES
ALLOWING FOR A BRISK BUT MILD SOUTHERLY FLOW TO DEVELOP OVER THE
AREA. FORECAST 850MB TEMPS WOULD SUPPORT HIGHS WELL INTO THE 50S AND
PERHAPS NEAR 60...THOUGH 925MB TEMPS ARE NOT QUITE AS MILD AND THAT
COULD PARTIALLY BE A RESULT OF A BIT MORE SNOW COVER. HAVE RAISED
HIGHS A BIT OVER THE BLENDED INITIALIZATION BUT THINKING CURRENT
FORECAST IS STILL TOO COOL...ESPECIALLY IN AREAS WITH LITTLE OR NO
SNOW COVER WHICH SHOULD BE A LARGE PORTION OF THE CWA BY SATURDAY.
COLD FRONT LOOKS TO MOVE THROUGH SAT NIGHT OR SUNDAY BRINGING COOLER
WEATHER FOR A COUPLE DAYS BUT IN THE TRANSIENT RATHER ZONAL FLOW GFS
AND ECMWF BOTH HINT AT ANOTHER HEALTHY WARM UP TOWARD MIDDLE OF NEXT
WEEK. PRECIP CHANCES THROUGH THE PERIOD LOOK LOW AND LARGELY
INCONSEQUENTIAL IF ANYTHING DOES FALL.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

RC

//DISCUSSION...UPDATED 18Z...

QUIET AVIATION WEATHER FOR NEXT 30 HOURS...AS SNOW ASSOCIATED WITH
WEAK LOW PRESSURE PASSING TO SOUTHWEST ON WEDNESDAY WILL REMAIN TO
THE SOUTHWEST OF THE TERMINALS. MID MVFR CIGS AT GYY SHOULD
SCATTER WITHIN NEXT HOUR OR SO AND MVFR OVER WISCONSIN EXPECTED TO
STAY TO THE NORTH THIS AFTERNOON...THOUGH COULD SEE FEW TO SCT
CLOUDS AT 020 FILL BACK IN A BIT. WIND SPEEDS WILL REMAIN
GENERALLY LIGHT THROUGHOUT THE TAF PERIOD...WITH DIRECTIONS
SHIFTING TO SOUTHERLY OVERNIGHT...SOUTHEAST WEDNESDAY MORNING AND
EAST-NORTHEAST BY MID TO LATE WEDNESDAY AFTERNOON.

RC


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH IN ALL ELEMENTS.

RC

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...SLIGHT CHANCE OF LIGHT SNOW.

THURSDAY...VFR.

FRIDAY...SLIGHT CHANCE OF LIGHT RAIN OR SNOW.

SATURDAY...VFR.

SUNDAY...VFR.

MONDAY...VFR.

RODRIGUEZ

&&

.MARINE...
436 AM CST

AS LOW PRESSURE OVER NORTHERN QUEBEC CONTINUES TO LIFT NORTH
TODAY...A TROUGH OF LOW PRESSURE AND FRONTAL BOUNDARY EXTENDING
FROM THIS LOW SOUTHWEST THROUGH THE CENTRAL GREAT LAKES WILL SHIFT
TO THE EASTERN GREAT LAKES AND SOUTHERN QUEBEC. WHILE THIS IS
OCCURRING...EXPECT THE ONGOING DIMINISHING TREND WITH THE
NORTHWEST AND WEST WINDS IN PLACE TO CONTINUE. WINDS ARE CURRENTLY
TO 30 KT ACROSS THE LAKE EARLY THIS MORNING BUT DO EXPECT THEM TO
DIMINISH TO 15 TO 25 KT THIS MORNING...AND THEN TO 10 TO 20 KT IN
THE AFTERNOON. BUILDING HIGH PRESSURE ACROSS THE REGION WILL
PROVIDE A PERIOD OF LIGHTER WINDS OVER THE LAKE TONIGHT INTO
WEDNESDAY AND PART OF WEDNESDAY NIGHT. DEPARTING LOW PRESSURE TO
THE SOUTH OF THE LAKE AND ANOTHER HIGH BUILDING ACROSS THE PLAINS
WILL HELP PROVIDE A TIGHTER PRESSURE GRADIENT OVER THE
LAKE...HELPING RETURN STRONGER WINDS BACK OVER THE LAKE THURSDAY
INTO THURSDAY NIGHT.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 PM TUESDAY.

&&

$$

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