247 PM CDT
SHORT TERM...TONIGHT THROUGH SATURDAY
...MAIN CONCERNS DURING THE SHORT TERM PERIOD CONTINUE TO
CENTER AROUND THE POTENT AUTUMN STORM SYSTEM CURRENTLY IMPACTING
THE REGION...
THE SURFACE LOW ACROSS WEST VIRGINA IS BEGINNING TO UNDERGO RAPID
INTENSIFICATION AS IT LIFTS NORTH NORTHWESTWARD INTO SOUTH OHIO.
WATER VAPOR IMAGERY THIS AFTERNOON SHOWS AN UPPER LEVEL JET
PUNCHING NORTHWARD ACROSS THE SOUTHEASTERN CONUS DOWN STREAM OF
THE THE UPPER LOW/TROUGH. LARGE SCALE ASCENT WITHIN THE LEFT EXIT
REGION OF THIS JET SHOULD LEAD TO RAPID DEEPENING OF THE SURFACE
LOW INTO THIS EVENING. WITH THE STRENGTHENING LOW...NORTHERLY
WINDS ARE STILL EXPECTED TO INCREASE TO ADVISORY CRITERIA LATER
THIS AFTERNOON AND EVENING...AND WARNING CRITERIA WINDS AT THE
LAKE FRONT. THEREFORE...I WILL KEEP THE CURRENT HEADLINES IN
PLACE.
THE OTHER CONCERN TONIGHT WILL BE WITH MODERATE TO HEAVY RAINFALL
POTENTIAL...ESPECIALLY ACROSS NORTHWESTERN INDIANA AND SOME OF MY
ADJACENT ILLINOIS COUNTIES. THE MODELS HAVE BEEN CONSISTENT IN
PRODUCING A RATHER IMPRESSIVE TROWAL EXTENDING ACROSS THESE
AREAS. THIS LOOKS TO DO TWO THINGS: FIRST IT SHOULD ENHANCE THE
LOWER LEVEL MESOSCALE FORCING AS A BAND OF MID LEVEL FRONTOGENESIS
DEVELOPS IN ASSOCIATION WITH THE TROWAL. THIS WILL HELP PRODUCE
BANDS OF MODERATE TO HEAVIER PRECIPITATION. SECONDLY...THE WARMER
MID LEVEL TEMPERATURES...TRANSPORTING WESTWARD WITHIN THE TROWAL
AIRSTREAM...WILL INCREASE THE WARM CLOUD DEPTH AND ALLOW HIGHER
PRECIPITABLE WATER AROUND AN INCH TO MOVE ACROSS THE AREA. ALL IN
ALL THIS LOOKS TO SET THE STAGE FOR A GOOD RAINFALL EVENT TONIGHT
ACROSS MY NORTHWEST INDIANA COUNTIES WESTWARD ACROSS PORTIONS OF
THE CHICAGO AREA. OVERALL...I WOULD EXPECT BETWEEN 1 TO AS MUCH AS
2 INCHES ACROSS THESE AREAS. HOWEVER FARTHER WEST AND
NORTH...AMOUNTS WILL BE MUCH LIGHTER...WITH ONLY A QUARTER TO A
HALF INCH POSSIBLE ACROSS NORTH CENTRAL ILLINOIS. THE WIND AND
RAIN WILL CONTINUE ON THURSDAY...BUT WILL ABATE DURING THE
AFTERNOON AS THE STORM SYSTEM LIFTS NORTHEAST ACROSS THE EASTERN
GREAT LAKES.
A SURFACE RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THIS LOW ON
THURSDAY NIGHT AND FRIDAY. THIS COULD ALLOW FOR TEMPERATURES TO DROP
NEAR 30 ACROSS PORTIONS OF NORTH CENTRAL ILLINOIS. I ADDED A MENTION
OF FROST TO THE GRIDS FOR THURSDAY NIGHT AND FRIDAY NIGHT AS THIS
HIGH MOVES ACROSS THE AREA AND PRODUCES SOME COOL MORNING LOW
TEMPERATURES UNDER CLEAR SKIES.
KJB
LONG TERM...SAT NIGHT THROUGH WED
A COUPLE WAVES RIPPLE THROUGH NORTHWEST FLOW SAT NIGHT THROUGH
SUNDAY. THE STRONGEST APPEARS TO BE MOVING THROUGH THE GREAT LAKES
SUNDAY AFTERNOON. WITH LIMITED MOISTURE AND BEST DYNAMICS PASSING
NORTH...WILL JUST MAINTAIN LOW CHANCE POPS FOR SUNDAY INTO SUNDAY
EVENING. UPPER RIDGING...SW SURFACE FLOW...AND SUNSHINE SHOULD BOOST
TEMPS INTO 60S MONDAY...POSSIBLY PUSHING 70 DOWN TOWARDS PONTIAC AND
WATSEKA. MONDAY APPEARS TO BE THE BEST DAY OF THIS 7 DAY PACKAGE.
CLOUDS AND SHOWERS SHOULD OVERSPREAD THE AREA TUESDAY AND TUESDAY
NIGHT AS NEXT WAVE DIGS INTO THE PLAINS. GFS HAS BAROCLINIC ZONE
SETTING UP OVER NORTHERN IL WITH EAST-NORTHEAST SURFACE WINDS OVER
MUCH OF THE AREA. THIS WOULD RESULT IN COOLER TEMPS THAN WHAT
GUIDANCE IS PROJECTING. ECMWF STILL PLACES SURFACE LOW FURTHER NORTH
KEEPING NORTHERN IL IN SOUTHERLY FLOW TUESDAY. WILL HAVE TO KEEP AND
EYE ON THIS AND MAY NEED TO ADJUST TEMPERATURES DEPENDING ON MODEL
TRENDS.
ALLSOPP
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* CEILINGS LOWERING TO IFR THIS EVENING.
* NNW TO NNE WINDS INCREASING THROUGH EARLY EVENING. GUSTS
APPROACHING AND POSSIBLY EXCEEDING 40 KT.
* RAIN INCREASING AND VISIBILITY LOWERING EARLY THIS EVENING.
PAW
//DISCUSSION...UPDATED 18Z...
A STRONG FALL STORM WILL IMPACT THE REGION THIS AFTERNOON INTO
THURSDAY...BRINGING STRONG WINDS...PERIODS OF RAIN AND IFR
CONDITIONS. A SURFACE LOW IN THE OHIO VALLEY AT 18Z WILL
STRENGTHEN AS IT MOVES INTO NORTHWEST OH TONIGHT BEFORE MOVING AWAY
TO THE NORTHEAST ON THURSDAY. AREAS OF HEAVIER RAIN ASSOCIATED
WITH THIS LOW HAVE BEEN SLOW TO MOVE INTO THE REGION. IT NOW LOOKS
MORE LIKE EARLY EVENING FOR ARRIVAL. MODEL GUIDANCE CONTINUES TO
INDICATE IFR CEILINGS WITH THE HEAVIEST RAIN. IFR TIMING HAS BEEN
ADJUSTED TO MATCH THE RAIN.
WIND SPEEDS INCREASING LATE THIS AFTERNOON AND EVENING AS THE LOW
MOVES CLOSER. THEN SPEEDS DECREASING ON THURSDAY AND DIRECTION
BECOMING MORE NORTHWEST AS THE LOW MOVES AWAY.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILINGS LOWERING TO IFR AND THE TIMING.
* MEDIUM CONFIDENCE IN WIND SPEED TREND...HIGH CONFIDENCE IN
DIRECTION.
* MEDIUM CONFIDENCE IN PRECIPITATION AND VISIBILITY TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...
THURSDAY NIGHT...MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...SLT CHC SHRA.
MONDAY...VFR.
TUESDAY...CHC SHRA.
BMD
&&
.MARINE...
300 PM CDT
STORM FORCE WINDS TO DEVELOP LATE THIS AFTERNOON AND EVENING...
LOW PRESSURE CENTERED OVER WESTERN WEST VIRGINA THIS AFTERNOON WILL
BEGIN TO MORE RAPIDLY INTENSIFY INTO THE EVENING AS IT MOVES TOWARD
WESTERN LAKE ERIE. SO FAR THE LOW HAS BEEN SLOW TO MOVE WHICH HAS
RESULTED IN A SLOWER EXPANSION OF STRONGER WINDS ACROSS CENTRAL AND
NORTHERN LAKE MICHIGAN SO FAR TODAY. SOUTHERN SECTIONS CONTINUE TO
SEE GALES WHICH BEGAN EARLIER THIS MORNING AND WILL LIKELY SEE AN
INCREASE TO STORM FORCE LATE THIS AFTERNOON AS THE LOW BEGINS TO
SPEED UP AND STRENGTHEN. SPEEDS NOW REACHING GALE FORCE ACROSS THE
NORTH AFTER A SLOW INCREASE THROUGH EARLY AFTERNOON. WITH THE LOW
STARTING TO STRENGTHEN AND SPEED ITS NORTHWARD PROGRESS EXPECT THAT
WINDS WILL RAPIDLY INCREASE THROUGH THE REST OF THE AFTERNOON AND
EARLY EVENING. STORM FORCE GUSTS MAY TAKE UNTIL 00Z OR SO TO
MATERIALIZE BUT WILL KEEP THE STORM WARNING START TIME AS-IS GIVEN
THE POTENTIAL FOR A RAPID INCREASE OVER THE NEXT 3-4 HRS. AM
THINKING THAT PEAK WINDS WILL OCCUR THIS EVENING AND EARLY TONIGHT
WHEN THE PRESSURE GRADIENT IS STRONGEST WITH GUSTS TO 60 KT A
POSSIBILITY SOUTH. DIRECTION WILL BE NORTH TO NORTHEAST WITH A SHIFT
TO THE NORTH THURSDAY MORNING. THE LOW WILL SLOW DOWN AND TRACK
SLIGHTLY WESTWARD INTO NORTHWEST OHIO THURSDAY MORNING. STORM FORCE
WINDS WILL CONTINUE INTO THE MORNING THEN DIMINISH TO GALES INTO THE
AFTERNOON AS THE LOW WEAKENS AND MOVES NORTHEAST INTO SOUTHERN
ONTARIO. HIGH PRESSURE WILL APPROACH THE MISSISSIPPI RIVER VALLEY
THURSDAY NIGHT AND FRIDAY WHICH WILL ALLOW WINDS TO DIMINISH BELOW
GALES SOMETIME THURSDAY EVENING. HIGH PRESSURE WILL CROSS THE LAKE
INTO SATURDAY KEEPING LIGHT WINDS IN PLACE WITH A WEST TO SOUTHWEST
DIRECTION. A WEAK FRONT MAY CROSS THE LAKE LATER SUNDAY BRINGING A
MODEST INCREASE IN SPEEDS WITH A STRONGER SYSTEM POSSIBLE TOWARD THE
MIDDLE OF NEXT WEEK.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ006-ILZ014 UNTIL 10 AM THURSDAY.
LAKESHORE FLOOD WARNING...ILZ006-ILZ014 UNTIL 4 PM THURSDAY.
WIND ADVISORY...ILZ005-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023-
ILZ032-ILZ033-ILZ039 UNTIL 10 AM THURSDAY.
IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 10 AM THURSDAY.
LAKESHORE FLOOD WARNING...INZ001-INZ002 UNTIL 9 PM THURSDAY.
WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 10 AM THURSDAY.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 3 PM WEDNESDAY.
STORM WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 3 PM THURSDAY.
&&
$$
