Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 251413
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
813 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 12Z...

* MVFR CEILINGS SCATTERING OUT THIS MORNING...THEN POSSIBLY
  RETURNING THIS AFTERNOON FOR A TIME.

KMD

//DISCUSSION...UPDATED 14Z...

MVFR CIGS ARE CLEARING IN NORTH CENTRAL ILLINOIS...SO EXPECT SOME
CLEARING THIS MORNING. LOWER MVFR STRATUS FROM 1000-2000 FT IS
MOVING SOUTHEAST THROUGH WISCONSIN...BUT GUIDANCE IS STILL MIXED
AS TO HOW INTACT IT WILL BE WHEN IT MOVES THROUGH NORTHEAST
ILLNOIS AND NW INDIANA. SEEMS AS THOUGH IT MAY TEMPORARILY GO
BROKEN. KEPT THE SCATTERED MENTION FOR NOW BUT MAY NEED TO GO
BROKEN IF IT KEEPS PROGRESSING.

KMD


PREVIOUS DISCUSSION FROM 12Z...

BETTER SNOW DEVELOPMENT CONTINUING TO DEPART TO THE EAST OF THE
TERMINALS EARLY THIS MORNING...WHILE SOME ADDITIONAL SCATTER
FLURRIES ARE APPROACHING AS ANOTHER MID LEVEL DISTURBANCE MOVES
ACROSS THE REGION. EXPECT THESE FLURRIES TO BE IN PLACE OVER THE
NEXT COUPLE OF HOURS BEFORE ALSO EXITING TO THE EAST...AS MVFR
CEILINGS REMAIN OVERHEAD. THESE MVFR CEILINGS STRETCH ACROSS MUCH
OF THE REGION THIS MORNING...BUT WITH SOME HOLES DEVELOPING NEAR
THE IOWA AND ILLINOIS BORDER. ALTHOUGH CONFIDENCE IS NOT TOO
HIGH...DID GO PESSIMISTIC WITH THE TAFS AND KEPT MVFR CEILINGS IN
PLACE THROUGH MID DAY. COULD SEE THIS HOLE FILLING BACK IN LATER
THIS MORNING...AND POSSIBLY HELPING TO KEEP THESE LOWER CEILINGS
IN PLACE A LITTLE LONGER INTO THE AFTERNOON. SHOULD OBSERVE AN
IMPROVING TREND INTO THE AFTERNOON BEFORE THESE CLOUDS SCATTER
ALTOGETHER...LEAVING ONLY HIGH LEVEL CLOUD COVER.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH WITH MVFR SCATTERING FOR A TIME...LOW ON WHETHER THEY
  RETURN AND FOR HOW LONG THIS AFTERNOON.

KMD

//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.

     SMALL CRAFT ADVISORY...LMZ743 UNTIL 10 AM TUESDAY.

&&

$$

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