Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 281925
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
125 PM CST FRI NOV 28 2014

.SHORT TERM...
340 AM CST

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH LIGHT SNOW THIS MORNING
WITH LIGHT ACCUMULATIONS FOR THE NORTHERN THIRD OF THE
CWA...SLIGHT POSSIBILITY FOR A BRIEF PERIOD OF FREEZING RAIN OR
SLEET EARLY THIS EVENING FOR FAR NORTHERN ILLINOIS...AND A WARM UP
FOR THIS WEEKEND.

LATEST RADAR IMAGERY SHOWING SOME ECHOES ACROSS THE WESTERN HALF
OF THE CWA...BUT WITH THIS NOT AMOUNTING TO ANYTHING AT THE
SURFACE AT THIS TIME. APPROACHING MID LEVEL IMPULSE WITH STRONG
WAA ONGOING ACROSS THE REGION IS ALLOWING FOR PERSISTENT LIFT OVER
THE CWA. LATEST OBS INDICATING STILL ONLY MID LEVEL CLOUD COVER IN
PLACE AS A GOOD AMOUNT OF LOW LEVEL DRY AIR IN PLACE IS LIMITING
SATURATION EARLY THIS MORNING. LATEST GUIDANCE STILL VARIES TO THE
EXTENT OF SNOWFALL THIS MORNING...VARYING FROM NONE TO SOME
DEVELOPMENT ACROSS NORTHERN ILLINOIS THROUGH THE 8-9 AM TIME
FRAME. HAVE MAINTAINED PREVIOUS FORECAST OF LIKELY POPS AS I DO
THINK IT WILL SNOW THIS MORNING WITH AREAS ACROSS NORTHWEST
ILLINOIS LIKELY OBSERVING SNOW WITHIN THE NEXT HOUR. I DO WONDER
THE EXTENT OF ANY MODERATE SNOW...ONCE AGAIN OWING TO THE DRIER
AIR. NONETHELESS...DEVELOPING SNOW FOR NORTHERN ILLINOIS EARLY
THIS MORNING WILL PROGRESS EAST OVER THE NEXT SEVERAL HOURS WITH
THE BEST CHANCES FOR MORE ACCUMULATING SNOW AROUND OF AROUND ONE
HALF INCH OR LESS LIKELY OCCURRING CLOSER TO THE
ILLINOIS/WISCONSIN BORDER. THIS PRECIP WILL DEPART TO THE
NORTHEAST BY MID MORNING...LEAVING DRY CONDITIONS AND CLOUDY SKIES
IN PLACE THROUGH EARLY AFTERNOON.

ALTHOUGH GUIDANCE NOT REALLY INDICATING IT...CURRENT STRONG WAA IN
PLACE THIS MORNING WILL LIKELY CONTINUE THIS AFTERNOON. WHILE THIS
OCCURS...ANOTHER UPSTREAM IMPULSE WILL DROP SOUTHEAST TOWARDS THE
CWA LATE THIS AFTERNOON INTO EARLY EVENING. I DID INTRODUCE SLIGHT
CHANCE POPS DURING THIS PERIOD MAINLY FOR THE FAR NORTHERN TIER OF
COUNTIES...AS IF IT WERE TO PRECIPITATE...COLUMN WOULD BE
SUPPORTIVE OF A WINTRY MIX. WITH DECENT WARMING IN THE LOW LEVELS
AND SURFACE TEMPS STILL HANGING AROUND FREEZING OR SLIGHTLY
BELOW...PRECIP COULD BE IN THE FORM OF LIGHT FREEZING RAIN. ONCE
AGAIN...AM NOT CONFIDENT WITH THIS SCENARIO BUT WITH PERSISTENT
FORCING THROUGHOUT TODAY...DONT THINK IT WOULD TAKE MUCH FOR ANY
PRECIP TO FALL OUT THE CLOUDS LATER TODAY. WILL NEED TO CONTINUE
MONITOR THIS TIME FRAME...MAINLY THROUGH THE 1-2Z TIME FRAME
BEFORE ENTIRE PRECIP SHIELD FULLY LIFTS NORTH OF THE CWA TONIGHT.
THIS WILL LEAVE DRY CONDITIONS IN PLACE THROUGH MOST OF THE
WEEKEND BEFORE SLIGHT CHANCE FOR RAIN ACROSS THE SOUTHEAST CWA
SUNDAY WITH THE APPROACH ANOTHER WAVE. MADE MINOR CHANGES TO HIGHS
SATURDAY AND SUNDAY WARMER TEMPS STILL ANTICIPATED...BUT LINGERING
CLOUD COVER COULD LIMIT THE POTENTIAL TO REACH GOING FORECAST
HIGHS.

RODRIGUEZ

&&

.LONG TERM...
340 AM CST

THE START OF NEXT WEEK WILL BE MARKED WITH A RETURN TO A COLDER
AIR MASS...AS HIGH TEMPS ON MONDAY ARE IN THE 20S. CONDITIONS WILL
GENERALLY BE DRY THROUGH MID WEEK...WITH THE POSSIBILITY OF LIGHT
SNOW ON TUESDAY. GUIDANCE THEN BEGINS TO VARY GOING TO
THURSDAY...WITH THE APPROACH ANOTHER SYSTEM. AT THIS TIME...IT
APPEARS TO BE TIMING ISSUES AS CHANCES FOR PRECIP RETURN ONCE
AGAIN LATE IN THE WORK WEEK...WITH SOME WARMING LIKELY DURING THIS
PERIOD.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 1915Z...

* SCT MVFR CIGS AROUND 020 DEVELOPING SHORTLY WITH INTERMITTENT BKN020
  NEXT FEW HOURS.

* SOUTH-SOUTHEAST WINDS GUSTING AROUND 20 KT THIS AFTERNOON.

* LOW CHANCE FOR MVFR TO LINGER THIS EVENING.

MDB

//DISCUSSION...UPDATED 1915Z...

LATEST ANALYSIS SHOWS A CORRIDOR OF MVFR CIGS DEVELOPING ON THE
LEADING EDGE OF LOW LEVEL WARM AIR AND EVEN A SUBTLE SURFACE WARM
FRONT FROM KSFY TO KIKK. WINDS MAKE A SUBTLE SHIFT TO DUE SOUTH
AND TEMPERATURES BOUNCE UP SEVERAL DEGREES BEHIND THIS BOUNDARY.
TRENDS SHOW THE SCT-BKN MVFR LIFTING NORTHEASTWARD SO HAVE ADDED
A TEMPO FOR BKN CIGS AROUND 020 FOR THE NEXT FEW HOURS. THE BAND
OF CLOUDS LOOKS TO BE FAIRLY NARROW AS SITES THAT WERE BKN HAVE
GONE SCT OR LESS SO IT MAY BE SHORT LIVED. WILL CONTINUE TO
MONITOR CIG TRENDS FOR THE EVENING WHICH ARE LESS CERTAIN.

FROM 18Z...

SOUTH TO SOUTH-SOUTHEAST WINDS HAVE BEGUN TO GUST TO ABOUT 20 KT
IN THE LAST HOUR OR TWO AND EXPECT THESE GUSTS TO CONTINUE THROUGH
THE AFTERNOON. THE DIRECTION SHOULD BECOME A BIT MORE SOUTHERLY
WITH TIME. THE MAIN QUESTION IS POTENTIAL FOR MVFR CIGS TO DEVELOP
EARLY THIS EVENING AND VSBY REDUCTION POTENTIAL OVERNIGHT.
GUIDANCE CONTINUES TO BACK PEDAL ON STRATUS DEVELOPMENT TO THE
WEST IN THE NEAR TERM AS NONE HAS DEVELOPED YET. WARMER AIR WILL
BEGIN TO PUSH INTO NORTHEASTWARD JUST ABOVE THE SURFACE INTO THE
EVENING SO IT IS POSSIBLE THAT SOME STRATUS COULD DEVELOP BUT
MOISTURE LOOKS LARGELY INSUFFICIENT. WILL INDICATE SCATTERED MVFR
CLOUDS FOR A TIME THIS EVENING BUT THIS MAY BE TOO PESSIMISTIC.
OTHERWISE MID CLOUDS WILL LOWER WITH THE PASSAGE OF AN UPPER WAVE.
THE PUSH OF WARM AIR DIMINISHES EARLY TONIGHT SO STRATUS WOULD
BECOME LESS LIKELY. WITH TEMPERATURES EXPECTED TO BE STEADY OR
EVEN WARM A FEW DEGREES TONIGHT...THE LACK OF A STRONG PUSH OF
MOISTURE OVERNIGHT AND STEADY SOUTH WINDS WIDESPREAD VSBY
REDUCTION IS NOT FAVORED THOUGH SOME PATCHY FOG COULD DEVELOP OVER
AREAS WITH BETTER SNOW PACK INCLUDING RFD. BREEZY SOUTH TO SOUTH-
SOUTHWEST WINDS WILL DEVELOP SATURDAY. WILL CONTINUE WITH A VFR
FORECAST WITH MID/HIGH CLOUD COVER.

MDB

//ORD AND MDW CONFIDENCE...UPDATED 1915Z...

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN WIND FORECAST.

* MEDIUM CONFIDENCE THAT MVFR CIG POTENTIAL THIS EVENING IS LOW.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...

SATURDAY NIGHT...MAINLY VFR CONDS.

SUNDAY...MAINLY VFR. POSSIBLE LGT RAIN IN THE MORNING.

MONDAY...VFR.

TUESDAY...SLIGHT CHANCE OF LGT SNOW EARLY WITH PATCHY MVFR CIGS.
OTHERWISE VFR.

WEDNESDAY...VFR.

THURSDAY...MAINLY VFR. PATCHY LIGHT RAIN OR SNOW WITH PATCHY MVFR
CIGS.

BEACHLER

&&

.MARINE...
123 PM CST

SOUTHERLY WINDS WILL REMAIN ELEVATED IN THE 20 TO 30 KT RANGE
THROUGH SATURDAY NIGHT AS AN AREA OF LOW PRESSURE TRACKS
NORTHEASTWARD FROM THE DAKOTAS TO NEAR JAMES BAY. THIS LOW WILL
DRIVE A COLD FRONT SOUTHWARD ACROSS LAKE MICHIGAN DURING THE DAY ON
SUNDAY. MUCH COLDER AIR AND STRONG NORTHERLY WINDS WILL SET UP IN
THE WAKE OF THIS FRONT AS A STOUT 30.71+ INCH HIGH BUILDS OVER THE
PLAINS AND UPPER MIDWEST. THIS SHOULD RESULT IN 30 KT WINDS LATER
SUNDAY INTO MONDAY...THOUGH A PERIOD OF GALE FORCE WINDS SUNDAY
NIGHT AS THE HEART OF THE COLD AIRMASS SPILLS OVER THE LAKE.

THE SURFACE HIGH WILL SHIFT EASTWARD OVER LAKE MICHIGAN BY AROUND
MONDAY EVENING...LEADING TO A PERIOD OF ABATING WINDS. HOWEVER...AS
THIS HIGH SHIFTS EAST OF THE LAKE...IT APPEARS THAT WINDS WILL
INCREASE OUT OF THE SOUTH AGAIN BY TUESDAY AS IT APPEARS ANOTHER
DECENT STORM SYSTEM WILL TRACK NORTHEASTWARD INTO SOUTHERN CANADA.
THIS COULD RESULT IN ANOTHER PERIOD OF GALE OR NEAR GALE FORCE
SOUTHERLY WINDS...ESPECIALLY ACROSS NORTHERN LAKE MICHIGAN.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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