454 PM CST
STRONGEST PRESSURE RISES ARE OVER NE IL RIGHT NOW...PLACING
STRONGEST WINDS NORTHEAST OF OUR AREA NOW. GIVEN ALL OBSERVATION
SITES ARE NOW WELL BELOW CRITERIA AND ONLY EXPECTED TO SUBSIDE
FURTHER HAVE ELECTED TO KILL THE NPW A BIT EARLY. WORKING TO
UPDATE GRIDS NOW AND WILL HAVE NEW GRIDS AND ZFP WILL BE OUT
SHORTLY.
IZZI
//PREV DISCUSSION...
330 PM CST
THE MAIN ISSUE THIS AFTERNOON HAS BEEN THE WINDS. STRONG
ISALLOBARIC PRESSURE RISES IN EXCESS OF 5MB/3HR AND GOOD COLD AIR
ADVECTION HAVE BEEN OCCURRING ACROSS PORTIONS OF NORTHERN ILLINOIS IN
THE WAKE OF THE SURFACE LOW. THIS HAS LEAD TO SOME PERIOD OF ADVISORY
CRITERIA WINDS ACROSS PORTIONS OF THE AREA THIS AFTERNOON. I EXPECT
THE WINDS TO ABATE LATE THIS AFTERNOON AND THIS EVENING FOLLOWING
THIS PRESSURE AND CAA SURGE.
IN ADDITION TO THE WINDS. A FEW AREAS ACROSS NORTH CENTRAL IL
EXPERIENCED THEIR FIRST SNOWFALL OF THE SEASON. THIS WAS ASSOCIATED
WITH AN AREA OF MID LEVEL FRONTOGENESIS WITHIN A WELL DEFINED
DEFORMATION ZONE ALONG THE NORTHWEST QUADRANT OF THE SURFACE LOW.
THE SNOW BAND WAS HEAVY ENOUGH TO RESULT IN SOME MINOR ACCUMULATIONS
AROUND 1 TO 3 TENTHS OF AN INCH ACROSS PORTIONS OF NORTH CENTRAL
ILLINOIS.
HOWEVER...THIS SYSTEM WILL QUICKLY LOSS IT GRIP ON THE AREA THIS
EVENING AS IT CONTINUES TO LIFT NORTHEASTWARD ACROSS THE UPPER GREAT
LAKES. THE NEXT SYSTEM OF INTEREST IS CURRENTLY EVIDENT IN THE WATER
VAPOR IMAGERY DIGGING SOUTH ACROSS SOUTHERN CANADA AND THE DAKOTAS.
THIS MID LEVEL DISTURBANCE IS FORECAST TO RAPIDLY DIG SOUTHWARD
ACROSS THE MID MISSISSIPPI RIVER VALLEY AND WESTERN GREAT LAKES ON
THURSDAY. THIS WILL HELP USHER IN EVEN COLDER AIR ACROSS THE REGION.
THIS COLDER AIR MASS SHOULD HELP STEEPEN THE LOW LEVEL LAPSE RATES
ACROSS THE AREA. THE COMBINATION THESE STEEPER LAPSE RATES AND THE
PRESENCE OF SOME WEAK LARGE SCALE FORCING FOR ASCENT WILL HELP SET
UP SOME SCATTERED LIGHT RAIN OR SNOW SHOWERS DURING THE DAY ON
THURSDAY ACROSS NORTHERN ILLINOIS AND NORTHWESTERN INDIANA. THERE
COULD ALSO BE SOME LAKE ENHANCEMENT TO THE SHOWERS...ESPECIALLY
ACROSS LOWER MICHIGAN SOUTHWARD INTO INDIANA.
A DECENT WARMING TREND LOOKS TO SET UP BY THE START OF THE WEEKEND
AS SOUTHWEST FLOW COMMENCES ACROSS THE AREA COMPLEMENTS OF A SURFACE
HIGH MOVING ACROSS THE SOUTHEASTERN CONUS. THIS COULD PUT
TEMPERATURES BACK INTO THE 50S TO NEAR 60 FOR SATURDAY AND SUNDAY.
FINALLY BY EARLY NEXT WEEK IT APPEARS THE WEATHER PATTERN ACROSS
NORTH AMERICA WILL REMAIN ACTIVE. UPPER LEVEL RIDGING ACROSS THE
PACIFIC REGION WILL SET UP A STRONG JET ACROSS THE NORTHEASTERN
PACIFIC. THIS WILL ENCOURAGE SEVERAL DISTURBANCES ACROSS THE
NORTHERN LATITUDES OF THE PACIFIC TO EJECT EASTWARD ATOP THIS
PACIFIC RIDGE AND THEN DIG SOUTHEASTWARD ACROSS THE WESTERN CONUS.
THIS LOOKS TO SET UP NEGATIVE HEIGHT ANOMALIES ACROSS MUCH OF THE
CENTRAL AND WESTERN CONUS BY EARLY NEXT WEEK. THIS WEATHER PATTERN
WOULD PLACE NORTHERN ILLINOIS INTO A SOUTHWEST FLOW PATTERN
ALOFT...POTENTIALLY SETTING THE STAGE FOR ANOTHER GOOD PRECIPITATION
EVENT. HOWEVER...ALTHOUGH THERE IS DECENT AGREEMENT AMONG THE
VARIOUS MODEL GUIDANCE WITH THE LARGER SCALE PATTERN...THERE ARE
STILL SOME DIFFERENCES APPARENT WITH THE SMALLER SCALE DETAILS IN
THE EXTENDED. THERE COULD BE A WET PERIOD EARLY NEXT WEEK AS A
SIGNIFICANT DISTURBANCE ACROSS THE SOUTHWESTERN CONUS EJECTS EASTWARD
ACROSS THE CENTRAL CONUS. BUT CONFIDENCE REMAINS ON THE LOW SIDE
REGARDING THE SPECIFICS OF TIMING OF BEST CHANCES OF RAIN EARLY NEXT
WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 02Z...
* MVFR CIGS THURSDAY.
* GUSTY WESTERLY WINDS DEVELOPING THURSDAY MORNING.
* CHANCE OF LIGHT RAIN/LIGHT SNOW SHOWERS LATE THURSDAY MORNING
INTO THURSDAY AFTERNOON. CMS
//DISCUSSION...UPDATED 00Z...
STRONG LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS THE UPPER
GREAT LAKES THIS EVENING AND WILL REACH JAMES BAY THURSDAY. THE
GRADIENT WILL CONTINUE TO SLOWLY WEAKEN THROUGH THE EVENING. IN
ADDITION...THE BACK EDGE OF THE CURRENT CLOUD DECK WILL STEADILY
BE MOVING EAST. AS SKIES CLEAR...WIND GUSTS SHOULD DIMINISH
THOUGH GRADIENT WILL STILL SUPPORT 10-12KTS THROUGH THE NIGHT.
FAIRLY CONFIDENT MVFR CIGS WILL BE GONE BY INDICATED TIMES BUT
THERE ARE SOME MID CLOUDS ACROSS SOUTHWEST WI/EASTERN IA SO NOT AS
CONFIDENT OF SKC THRU THE NIGHT.
NEXT UPPER LEVEL WAVE CURRENTLY MOVING SOUTH OUT OF CANADA ACROSS
NORTHERN MN. THIS FEATURE WILL TURN SOUTHEAST AND MOVE ACROSS THE
AREA THURSDAY. EXPECT A BKN/OVC VFR DECK APPROACHING BY SUNRISE
AND THEN WILL LIKELY LOWER INTO MVFR BY MID/LATE MORNING...THOUGH
CONFIDENCE ON EXACT HEIGHTS AS WELL AS THE DURATION OF ANY MVFR
CIGS IS RATHER LOW. SEVERAL LOCATIONS REPORTING LIGHT SNOW SHOWERS
WITH THIS FEATURE AND EXPECT AT LEAST A CHANCE OF SOME LIGHT RAIN
MIXED WITH LIGHT SNOW SHOWERS...MAINLY IN THE EARLY/MID AFTERNOON
HRS. WHILE A VCSH MIGHT BE REASONABLE FROM THIS DISTANCE...NOT
SURE ON OVERALL COVERAGE AND FOR THAT REASON...OPTED TO KEEP THIS
FORECAST DRY AND WILL TAKE A CLOSER LOOK WITH THE 06Z TAFS LATER
THIS EVENING.
WESTERLY WINDS BEGIN TO INCREASE BY MID MORNING THURSDAY WITH
SOUNDINGS SUGGESTING GUSTS IN THE 20-25KT RANGE POSSIBLE FOR MUCH
OF THE DAY. A RIDGE OF HIGH PRESSURE WILL THEN MOVE ACROSS THE
AREA THURSDAY NIGHT INTO FRIDAY MORNING. WINDS SHOULD QUICKLY
DIMINISH WITH SUNSET THURSDAY WITH CLEARING SKIES AS THE UPPER
WAVE MOVES SOUTHEAST OF THE AREA. CMS
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* MEDIUM CONFIDENCE MVFR CIGS WILL DEVELOP THURSDAY...LOW
CONFIDENCE REGARDING TIMING AND HEIGHTS.
* HIGH CONFIDENCE WESTERLY WINDS WILL GUST 20+ KTS THURSDAY...
MEDIUM CONFIDENCE ON TIMING.
* LOW CONFIDENCE REGARDING LIGHT RAIN/LIGHT SNOW SHOWERS THURSDAY.
CMS
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...BREEZY. SOUTHWEST WINDS GUSTING 20+ KTS. VFR.
SATURDAY...VFR.
SUNDAY...WINDY. SOUTHWEST WINDS GUSTING 30+ KTS. VFR.
MONDAY...CHANCE OF RAIN. MVFR POSSIBLE.
TUESDAY...SLIGHT CHANCE OF RAIN. CMS
&&
.MARINE...
330 PM CST
A DEEPENING LOW PRESSURE SYSTEM THAT MOVED OVER THE LAKE TODAY WAS
LOCATED NEAR LUDINGTON THIS AFTERNOON AND WILL CONTINUE MOVING
NORTHEAST TOWARD JAMES BAY OVERNIGHT. WINDS IN THE WAKE OF THIS
LOW HAVE BEEN GUSTING TO 40 KTS OR MORE...ESPECIALLY AT THE HIGHER
PLATFORMS. EXTENDED THE EXISTING HEADLINES TO ACCOUNT FOR THESE
STRONGER GUSTS PERSISTING INTO THE EARLY MORNING PERIOD. ONE OR
TWO PLATFORMS ON THE MICHIGAN SIDE OF THE LAKE ALSO REPORTED GUSTS
INTO THE VERY LOW STORM FORCE CATEGORY...BUT SHIP OBSERVATIONS AND
LOWER PLATFORMS ARE TOPPING OUT AT THE GALE FORCE RANGE. WINDS
ACROSS THE LAKE VARY QUITE A BIT IN DIRECTION THIS AFTERNOON BUT
WILL BECOME UNIFORMLY WEST OVERNIGHT. WEST FLOW THEN PERSISTS INTO
FRIDAY MORNING BEFORE WINDS BACK SOUTH AHEAD OF A NEW LOW PRESSURE
SYSTEM APPROACHING LAKE SUPERIOR. SOUTH TO SOUTHWEST WINDS
CONTINUE THROUGH THE WEEKEND AS THE LOW PASSES NORTH OF THE LAKES.
LENNING
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 2 AM THURSDAY.
GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ868 UNTIL 8 AM THURSDAY.
&&
$$
