343 PM CDT
FOR THE REMAINDER OF THE AFTERNOON AND EVENING...MILD CONDITIONS
CONTINUE ACROSS NORTHERN ILLINOIS AND NORTHWEST INDIANA.
TEMPERATURES WILL CONTINUE TO INTO THE MIDDLE TO UPPER 70S ACROSS
THE NORTHERN PORTIONS OF THE CWA NEAR THE WISCONSIN BORDER...TO
AROUND 80 TO THE FAR SOUTH. A WEAK LAKE BREEZE HAS PUSHED INLAND
FROM DOWNTOWN CHICAGO TO NWRN LAKE COUNTY...ALLOWING THE LAKE FRONT
LOCATIONS NORTH OF CHICAGO TO REMAIN A LITTLE COOLER...WITH HIGHS
TOPPING OUT TODAY IN THE LOWER 70S. OVERNIGHT...EXPECT SKIES TO BE
MOSTLY CLEAR. AS SFC DEWPOINTS HAVE REBOUNDED INTO MIDDLE 50S
TODAY...EXPECT THAT OVERNIGHT LOWS WILL NOT BE QUITE AS LOW AS
RECENTLY...THIS TEMPERATURES ONLY DROPPING GENERALLY INTO THE MIDDLE
50S.
THE UPPER LEVEL PATTERN IS FINALLY SHOWING SOME SIGNS OF EASTWARD
PROGRESSION...SIGNALING A CHANGE IN THE WEATHER. THE PERSISTENT
UPPER LEVEL RIDGE IS BEGINNING TO MOVE EASTWARD AS AN UPPER LOW
RIDES NWD THROUGH THE NRN PLAINS AND INTO SCNTRL CANADA. CONDITIONS
ACROSS THE AREA SHOULD REMAIN PLEASANT FOR A COUPLE MORE DAYS AS THE
UPPER RIDGE SLOWLY BUILDS EWD AND HIGH AMPLITUDE...FULL-LATITUDE
TROUGHING DEVELOPS OVER THE CNTRL PLAINS. EXPECT LITTLE CHANGE IN
THE SENSIBLE WEATHER CONDITIONS FOR TUESDAY AS A RIDGE OF SFC HIGH
PRESSURE EXTENDS FROM SERN CANADA...THROUGH THE ERN GREAT LAKES...TO
THE MIDDLE MISSISSIPPI VALLEY. LOW LEVEL FLOW WILL REMAIN
SELY-SSELY THROUGH THE DAY...WITH FOR TUESDAY REMAINING VERY SIMILAR
TO RECENT DAYS...WITH ONLY PERHAPS SOME INCREASING MID AND HIGH
CLOUDINESS.
WEDNESDAY IS SHAPING UP TO BE CHANGE DAY AS A COLD FRONT ASSOCIATED
WITH THE APPROACHING...DEVELOPING TROUGH TRACKS THROUGH THE CNTRL
PLAINS. THERE ARE STILL SOME MODEL DISAGREEMENTS...ESPECIALLY WITH
THE TIMING OF THE FRONTAL PASSAGE. HAVE GENERALLY FOLLOWED THE
GFS/SREF SOLUTION WHICH HAS BEEN VERY CONSISTENT IN TIMING OF THE
FROPA WITH RECENT RUNS...ALTHOUGH OVERALL...THE TIMING DIFFERENCES
AMONG THE MODELS IS NOT VERY LARGE. GENERALLY...EXPECT THE FROPA TO
OCCUR IN THE LATE EVENING HOURS. HAVE NOT MADE MUCH CHANGE TO THE
ASSOCIATED PCPN FORECAST AND STILL EXPECT A PERIOD OF SHOWERS
WITH...WITH PCPN POSSIBLY MOVING INTO THE ROCKFORD AREA AS EARLY AS
LATE WEDNESDAY AFTERNOON. EXPECT THAT THE PCPN WILL NOT CLEAR THE
EASTERN PORTIONS OF THE CWA UNTIL LATE THURSDAY NIGHT OR FRIDAY
MORNING. STILL EXPECT THAT THERE MAY BE A CHANCE FOR SOME
ISOLD...EMBEDDED THUNDER WITH THE FRONT...BUT INSTABILITY IS
EXPECTED TO BE RATHER MODEST...SO HAVE TRIMMED BACK THE SLIGHT
CHANCE THUNDER AREAS IN THE GRIDS...AND HAVE CONFINED IT MORE
CLOSELY WITH THE FRONTAL BOUNDARY.
TEMPERATURES SHOULD DROP OFF SIGNIFICANTLY FOLLOWING THE FROPA WITH
850MB TEMPS DROPPING TO ARND 2C BY FRIDAY MORNING. BY
THURSDAY...HIGHS SHOULD BE IN THE MIDDLE 60S. AS THE COLD ADVECTION
REALLY KICKS IN OVERNIGHT THURSDAY AND FRIDAY...HIGHS BY FRIDAY
SHOULD BE MUCH MORE SEASONABLE...IN THE UPPER 50S TO LOWER 60S.
FOR THE REMAINDER OF THE LONGER TERM FORECAST PERIOD...FOR SATURDAY
THROUGH MONDAY...CONDITIONS WILL MODERATE THROUGH THE WEEKEND AS
ANOTHER UPPER RIDGE BUILDING OVER THE WRN CONUS MOVES OUT OVER THE
PLAINS. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR GENERALLY
DRY WEATHER THROUGH THE WEEKEND AND TEMPERATURES REBOUNDING BACK
INTO MIDDLE 60S...TO LOWER 70S BY SUNDAY.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WIND DIRECTION/LAKE BREEZE POTENTIAL. CMS
//DISCUSSION...UPDATED 18Z...
WINDS ARE THE PRIMARY CONCERN THROUGH THE PERIOD. ACAR SOUNDINGS
FROM THE PAST SEVERAL HRS INDICATE LOW LEVELS WINDS...950MB...
GENERALLY LESS THAN 10 KT...BUT INCREASING. FORECAST SOUNDINGS
SUGGEST LOW LEVEL WINDS INCREASING TO 12-16 KTS THIS AFTERNOON.
WHILE A LAKE BREEZE MAY FORM...AND PERHAPS ALREADY SHOWING UP ON
THE TERMINAL RADARS NORTH OF DOWNTOWN CHICAGO...THESE INCREASING
LOW LEVEL WINDS SHOULD BE STRONG ENOUGH TO PREVENT A LAKE BREEZE
FROM REACHING ORD/MDW. OVERALL GRADIENT SUPPORTS A PREVAILING
SOUTH/SOUTHEAST WIND INTO TUESDAY AFTERNOON WITH SPEEDS
DIMINISHING OVERNIGHT. WINDS BEGIN TO TURN MORE EASTERLY TUESDAY
AFTERNOON INTO TUESDAY EVENING...PERHAPS AIDED BY A LAKE BREEZE.
A WEAK WAVE WILL LIFT NORTHEAST ACROSS NORTHWEST IL AND SOUTHERN
WI TUESDAY MORNING INTO TUESDAY AFTERNOON. A FEW SHOWERS ARE
POSSIBLE WITH THIS FEATURE...POSSIBLY AFFECTING RFD. HAVE OPTED
TO LEAVE OUT ANY MENTION OF PRECIP WITH THIS FORECAST GIVEN
EXPECTED ISOLATED COVERAGE AND SHORT DURATION...BUT WILL NEED TO
BE MONITORED WITH LATER FORECASTS. CMS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE REGARDING WINDS/SPEEDS. CMS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH EARLY WEDNESDAY...VFR
LATE WEDNESDAY THROUGH THURSDAY...OCNL SHRA WITH CHC TSRA
FRIDAY AND SATURDAY...VFR
SUNDAY...CHC SHRA
SHEA
&&
.MARINE...
204 PM CDT
THE MAIN CONCERN DURING THE PERIOD WILL BE THE POTENTIAL FOR A
PERIOD OF LOW END GALES ON FRIDAY AND FRIDAY NIGHT. A POTENT AREA OF
LOW PRESSURE IS EXPECTED TO DROP SOUTHEAST ACROSS THE UPPER MISSISSIPPI
RIVER VALLEY AND ACROSS THE GREAT LAKES LATER THIS WEEK. THIS
SYSTEM LOOKS TO PRODUCE A PERIOD OF SIGNIFICANT WINDS ACROSS THE
LAKE AS MUCH COLDER AIR SPILLS ACROSS THE REGION.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
