357 PM CDT
OUTSIDE OF SOME PERSISTENT GUSTY WINDS...NO REAL CONCERNS IN THE
NEAR TERM BUT WITH CLOUD COVER AND CHANCES FOR SHOWERS ON THE
INCREASE LATE TONIGHT INTO EARLY SUNDAY...MAINLY FOR FAR NORTHERN
ILLINOIS.
STRONGER WINDS/GUSTS HAVE PERSISTED TODAY AS FAIRLY STRONG
PRESSURE GRADIENT REMAINS ACROSS THE REGION...AS LARGE UPPER LEVEL
LOW CONTINUES TO SLOWLY SHIFT JUST EAST OF THE REGION. SUNNY
CONDITIONS IN PLACE TODAY ALLOWED FOR SOME PRETTY GOOD MIXING TO
OCCUR TODAY HELPING WITH STRONGER WINDS ALOFT TO MIX TO THE
SURFACE...WITH MANY LOCATIONS ACROSS NORTHEAST ILLINOIS AND
NORTHWEST INDIANA WERE ABLE TO OBSERVE 30 TO 40 MPH GUSTS TODAY.
EXPECT THESE STRONGER WINDS TO CONTINUE LATE THIS AFTERNOON BEFORE
THEY SLOWLY DROP OFF AS ATMOSPHERE DECOUPLES. THE FULL SUNSHINE
TODAY WAS ALSO AN INDICATOR OF HOW MUCH DRIER CONDITIONS THERE
WERE TODAY...WITH LITTLE IF ANY CU DEVELOPMENT. THIS DRIER AIR WAS
ALSO REALIZED AT THE SURFACE WITH DEW POINT TEMPS TODAY FALLING
INTO THE LOWER 30S OVER MUCH OF THE CWA...WITH THIS DRIER AIR IN
PLACE DEFINITELY PLAYING A FACTOR ON OUR PRECIP CHANCES TONIGHT
INTO EARLY SUNDAY MORNING.
CURRENTLY AM NOT TOO THRILLED AT THE IDEA OF CHANCES FOR SHOWERS
TONIGHT...HAVING SINCE PULLED BACK ON POPS WITH THE LATEST
FORECAST PACKAGE. GUIDANCE CONTINUES TO INDICATE THAT CURRENT
SHORT WAVE TROUGH/S PUSHING ACROSS THE NORTHERN PLAINS WILL SHIFT
EAST AND MOVE INTO THE REGION LATER TONIGHT OUT AHEAD OF MAIN VORT
MAX SLOWLY DROPPING SOUTH THROUGH SOUTHERN CANADA. AS THIS
OCCURS...SOUTHERLY FLOW OUT AHEAD OF THIS SYSTEM WILL HELP ADVECT
A WARMER AIRMASS FURTHER NORTH. MODEL GUIDANCE IS HINTING THAT MID
LEVEL FRONTOGENESIS WILL WORK ITS WAY EAST ACROSS SOUTHERN
WISCONSIN AND NORTHERN ILLINOIS AFTER THE 6Z TIME FRAME. THIS
FORCING SHOULD ALLOW FOR SOME PRECIP TO DEVELOP ACROSS OUR
NORTHERN CWA LATE TONIGHT INTO EARLY SUNDAY. ALTHOUGH...GUIDANCE
CONTINUES TO DIFFER WITH HANDLING THIS SYSTEM/FORCING/PRECIP
TONIGHT INTO EARLY SUNDAY MORNING. I HAVE TRENDED MORE TOWARDS THE
DRIER GUIDANCE DUE TO THE MUCH DRIER CONDITIONS IN PLACE. FALLING
DEWPOINTS INTO THE LOWER 30S SHOWS ME JUST HOW MUCH DRIER AIR IS
ALOFT...WITH FORECAST SOUNDINGS INDICATING THIS DRIER AIR CLOSER
TOWARDS EARLY SUNDAY MORNING. SO WITH FORCING REMAINING FAIRLY
PROGRESSIVE GOING INTO THIS PERIOD AND THE PREVIOUSLY MENTIONED
DRIER AIR...THINK THAT ANYTHING THAT DOES DEVELOP WILL BE LIGHT
AND BRIEF IN NATURE. THEN WITH SURFACE REFLECTION SHIFTING ACROSS
THE CWA SUNDAY MORNING AND SLIGHTLY MORE MOIST CONDITIONS IN
PLACE...THERE WILL ALSO BE A SLIGHTLY BETTER CHANCE FOR SHOWERS.
THEN AS QUICKLY AS THESE PRECIP CHANCES ARRIVE...THEY WILL BE
QUICK TO EXIT THE REGION WITH DRY CONDITIONS FORECAST FOR SUNDAY
AFTERNOON.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 21Z...
* GUSTY WEST WINDS THIS AFTERNOON.
IZZI
//DISCUSSION...UPDATED 18Z...
STRONG DEEPENING LOW PRESSURE CONTINUES TO LIFT SLOWLY AWAY FROM
THE AREA ACROSS EASTERN CANADA EARLY THIS AFTERNOON...THOUGH GUSTY
WEST WINDS CONTINUE ACROSS THE FORECAST AREA IN THE WAKE OF THIS
DEPARTING SYSTEM. SURFACE OBSERVATION TRENDS RELATE VERY WELL TO
MODEL FORECAST SOUNDING WIND PROFILES...WITH SUSTAINED WINDS
APPROACHING 20 KT AND GUSTS NEAR 30 KT EXPECTED TO CONTINUE THIS
AFTERNOON. COMBINATION OF LOSS OF DIURNAL MIXING AND A WEAKENING
OF THE SURFACE PRESSURE GRADIENT TOWARD EVENING SHOULD ALLOW WINDS
TO DIMINISH QUICKLY AND BACK WEST-SOUTHWEST AFTER SUNSET.
ATTENTION THEN TURNS TO A QUICK MOVING MID-LEVEL DISTURBANCE
APPROACHING FROM THE NORTHERN PLAINS LATER TONIGHT AND SUNDAY
MORNING. ASCENT PRODUCED BY THIS FEATURE IS PROGGED TO SPREAD MID-
LEVEL CLOUDS ACROSS THE REGION...WITH DRY LOW LEVEL AIR CURRENTLY
ACROSS THE AREA WORKING AGAINST DEVELOPMENT OF WIDESPREAD
PRECIPITATION AND LOWER CLOUD COVER. GUIDANCE IN GENERAL AGREEMENT
IN BAND OF LIGHT RAIN DEVELOPING FROM SOUTHERN MN TO SOUTHERN WI
OVERNIGHT AND PERHAPS JUST CLIPPING NORTHERN IL TERMINALS WITH A
LITTLE VFR LIGHT RAIN FROM A MID-DECK INTO SUNDAY MORNING. WHILE
THIS SCENARIO SEEMS FAIRLY LIKELY...CONFIDENCE ON COVERAGE AND
EXACT TIMING FOR OUR POINT FORECAST TERMINAL LOCATIONS IS MEDIUM
AT BEST. ANY LIGHT PRECIP SHOULD EXIT TO THE EAST-SOUTHEAST BY
SUNDAY AFTERNOON HOWEVER...WITH PASSAGE OF MID-LEVEL WAVE AND
SURFACE TROUGH/WEAK COLD FRONT.
SURFACE TROUGH WITH THIS SYSTEM IS EXPECTED TO BACK THE WINDS TO
THE SOUTHWEST OVERNIGHT...BEFORE VEERING BACK TO THE WEST-
NORTHWEST BY MID-LATE SUNDAY MORNING. SOME QUESTION AS TO DETAILS
OF WIND DIRECTION NEAR THE TROUGH AXIS EARLY SUNDAY...AS VARIOUS
GUIDANCE DEPICT EITHER AN OPEN TROUGH WITH A SIMPLE WIND SHIFT
FROM SOUTHWEST TO WEST-NORTHWEST...WHILE OTHERS INDICATE A
SLIGHTLY MORE ORGANIZED CYCLONIC CIRCULATION. HAVE INDICATED A
BRIEF PERIOD OF VARIABLE DIRECTION WITH TROUGH PASSAGE BASED ON
THIS...WITH WINDS IN EITHER CASE LESS THAN 10 KT EARLY SUNDAY
BEFORE TROUGH PASSES.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 21Z...
* HIGH CONFIDENCE IN ALL ELEMENTS THROUGH TONIGHT.
* MEDIUM-LOW CONFIDENCE IN PRECIP EXTENT/TIMING SUNDAY MORNING.
RATZER/IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY THROUGH TUESDAY...VFR WITH PERIODIC RAIN CHANCES...SOME
MVFR POSSIBLE.
WEDNESDAY AND THURSDAY...VFR.
JEE
&&
.MARINE...
301 PM CDT
DEEP LOW PRESSURE WILL CONTINUE TO DRIFT VERY SLOWLY NEAR JAMES BAY
ONTARIO THROUGH MONDAY...WHILE SLOWLY FILLING AND WEAKENING. THIS
WILL MAINTAIN A STRONG WESTERLY GRADIENT ACROSS LAKE MICHIGAN...
THOUGH GRADUAL WEAKENING WILL OCCUR TONIGHT AS THE LOW STOPS
DEEPENING. UNFORTUNATELY...IT APPEARS THAT WINDS WILL RAMP UP AGAIN
TO GALE FORCE ON THE NORTHERN HALF OF THE LAKE SUNDAY AFTERNOON AS A
REINFORCING PUSH OF COOLER AIR WRAPS AROUND THE NEARLY STATIONARY
LOW. GALES WILL LIKELY PERSIST ON NORTHERN LAKE MICHIGAN INTO MONDAY
MORNING...BEFORE THE OLD LOW FINALLY BEGINS TO FILL MORE RAPIDLY AND
LIFTS OUT ACROSS QUEBEC. STRONG HIGH PRESSURE WILL BUILD SOUTHEAST
FROM THE CANADIAN PRAIRIES AND NORTHERN PLAINS MID-WEEK...WHICH WILL
MAINTAIN MODEST NORTHERLY WINDS ACROSS LAKE MICHIGAN THROUGH THE
LATER PARTS OF THE FORECAST PERIOD.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 1 AM SUNDAY.
GALE WARNING...NEARSHORE WATERS UNTIL 7
PM SATURDAY.
&&
$$
