355 PM CDT
MAIN FORECAST CONCERNS ARE WITH A COOLING TREND THROUGH THE MIDDLE
PART OF THE WEEK...AS WELL AS PRECIP CHANCES INCREASING ACROSS THE
CWA TOWARDS MID WEEK.
SURFACE TROUGH OF LOW PRESSURE AND ASSOCIATED BOUNDARY HAVE SINCE
PUSHED SOUTH OF THE CWA THIS AFTERNOON...WITH ANY LINGERING SHOWERS
ALSO HAVING SINCE PUSHED SOUTH. LATEST RADAR IMAGERY IS SHOWING
SOME WEAK ECHOS JUST SOUTH OF THE CWA ACROSS CENTRAL ILLINOIS AND
CENTRAL INDIANA...BUT MOST OF THIS IS JUST IN THE FORM OF MID
LEVEL CLOUD COVER. AS ANOTHER PUSH OF MUCH DRIER CONTINUES TO PUSH
SOUTH THIS AFTERNOON...CLOUD COVER HAS ALSO SLOWLY ERODED. ANY
STRATOCU WHICH HAS DEVELOPED THIS AFTERNOON WILL ERODE ONCE AGAIN
THIS EVENING WITH ANY REMAINING MID AND HIGH LEVEL MOISTURE TO
CONTINUE EXITING TO THE SOUTH. THIS WILL RESULT IN CLEAR AND QUIET
CONDITIONS FOR TONIGHT INTO EARLY MONDAY MORNING. WITH A COLDER
AIR MASS MOVING IN FROM THE NORTH TEMPERATURES TONIGHT WILL BE ON
THE CHILLY SIDE. GUIDANCE WAS PROVIDING NIGHT TIME LOWS IN THE LOW
TO MID 30S ACROSS PORTIONS OF THE CWA FOR TONIGHT...BUT HAVE
STRAYED AWAY FROM GUIDANCE BY A COUPLE OF DEGREES. DESPITE
CLEARING SKIES AND A COOLER AIR MASS IN PLACE...A STRONG PRESSURE
GRADIENT WITH FAIRLY STRONG FLOW NOT TOO FAR OFF OF THE SURFACE
WILL REMAIN. FEEL THAT THIS STRONGER WIND REGIME WILL HELP KEEP
SOME TYPE OF SPORADIC BOUNDARY LAYER MIXING AND LIMIT GOOD
RADIATIONAL COOLING TONIGHT. SO HAVE GONE A COUPLE OF DEGREES
ABOVE GUIDANCE WITH FORECAST LOWS IN THE UPPER 30S ACROSS THE
NORTHERN HALF OF THE CWA AND LOWS AROUND 40 ACROSS THE SOUTH. THIS
STRONGER WIND FIELD WILL ALSO LIMIT ANY POSSIBLE FROST
DEVELOPMENT.
AS ANOTHER SHORT WAVE TROUGH APPROACHES FROM THE WEST ON
MONDAY...CLOUD COVER WILL ONCE AGAIN BE ON THE INCREASE. ALTHOUGH
WITH ITS FORECAST TRACK TO TAKE THIS FEATURE AND FORCING FURTHER
SOUTH...THIS MAIN CLOUD SHIELD SHOULD AFFECT THE SOUTHERN CWA.
GUIDANCE IS EVEN HINTING AT THE POSSIBILITY OF A STRAY SHOWER FOR
THIS SAME AREA...BUT HAVE ONLY SLIGHT CHANCE POPS FOR THESE AREAS
IN THE AFTERNOON. THEN TEMPERATURES WILL BE ON A DOWNWARD TREND
INTO MID WEEK AS A LONGWAVE TROUGH TO THE NORTH DIGS SOUTH ACROSS
THE MIDWEST MONDAY NIGHT INTO TUESDAY...WITH ANOTHER STRONG PUSH
OF COLDER AIR TO OCCUR. ALSO...UPPER LEVEL SUPPORT ALONG WITH
STEEPENING LAPSE RATES WILL SUPPORT THE DEVELOPMENT FOR CLOUD
COVER/SHOWERS ON TUESDAY. LATEST GUIDANCE IS IN FAIR AGREEMENT
WITH THIS UPPER LEVEL TROUGH CUTTING ITSELF OFF AS IT SLOWLY
SLIDES TO THE EAST TUESDAY NIGHT INTO WEDNESDAY. THIS IS GOING TO
SETUP A PATTERN FOR AN EXTENDED PERIOD OF CLOUD COVER AND CHANCES
FOR PRECIP. NOT ONLY WILL SYNOPTIC SUPPORT BE IN PLACE...BUT THIS
MUCH COLDER AIR MASS WILL SUPPORT THE DEVELOPMENT FOR LAKE EFFECT
SHOWERS. THERMAL PROFILES ALONG WITH STEERING FLOW ALOFT WILL HELP
MAINTAIN CHANCES FOR RAIN SHOWERS GOING INTO LATE THURSDAY NOT
ONLY FOR NORTHWEST INDIANA BUT ALSO NORTHEAST ILLINOIS. DESPITE A
MUCH COLDER AIR MASS ONCE AGAIN DROPPING SOUTH INTO
THURSDAY...ONLY RAIN SHOWERS ARE FORECAST AT THIS TIME AS
CONDITIONS OVER THE LAKE REMAIN FAIRLY WARM TO WARRANT LEAVING OUT
ANY MENTION OF FROZEN PRECIPITATION AT THIS TIME.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 21Z...
* GUSTY WEST-NORTHWEST WINDS UNTIL SUNSET.
RATZER/IZZI
//DISCUSSION...UPDATED 18Z...
REGION REMAINS UNDER INFLUENCE OF DEEP WINDY LOW PRESSURE SYSTEM
TO THE NORTHEAST OF THE GREAT LAKES. MID-LEVEL DISTURBANCE AND
ASSOCIATED WEAKER SURFACE LOW HAVE PASSED ACROSS THE FORECAST AREA
THIS MORNING...WITH COLD FRONT NOW MOVING OUT OF THE EASTERN
TERMINALS. RAIN ASSOCIATED WITH THIS FRONT AND MID-LEVEL
DISTURBANCE HAS EXITED THE AREA...AND OTHER THAN SOME LINGERING
PATCHY HIGH CLOUD FROM STRONG JET OVERHEAD THIS AFTERNOON...
SHOULD SEE A DECREASE IN THE MID CLOUD COVER AND CONTINUED VFR
CONDITIONS.
WITH THE WEAK SURFACE LOW AND COLD FRONTAL TROUGH HAVING MOVED
THROUGH THE TERMINALS...THE GRADIENT WILL AGAIN TIGHTEN THIS
AFTERNOON WHICH ALONG WITH STEEPENING LOW LEVEL LAPSE RATES WILL
PROVIDE A DEEP MIXED LAYER. FORECAST SOUNDINGS CONTINUE TO DEPICT
GUST POTENTIAL IN THE 25 KT RANGE THIS AFTERNOON UNTIL THE
BOUNDARY LAYER DECOUPLES THIS EVENING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 21Z...
* HIGH CONFIDENCE ALL ELEMENTS.
RATZER/IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY...VFR.
TUESDAY...CHC SHRA. MVFR CIGS POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
IZZI
&&
.MARINE...
202 PM CDT
STRONG WEST-NORTHWEST WINDS...GALE FORCE ESPECIALLY ON THE CENTRAL
AND NORTHERN PARTS OF THE LAKE...WILL REMAIN THE MAIN FORECAST FOCUS
THROUGH MONDAY AFTERNOON.
DEEP LOW PRESSURE HAS BECOME NEARLY STATIONARY TO THE NORTH OF JAMES
BAY. THIS LOW WILL SLOWLY FILL AS IT CONTINUES TO WOBBLE OVER THE
JAMES BAY AREA THROUGH MONDAY...THEN WILL WEAKEN MORE QUICKLY AS IT
FINALLY MOVES OFF TO THE EAST ACROSS QUEBEC MONDAY NIGHT INTO
TUESDAY. WHILE THE LOW REMAINS STATIONARY TONIGHT AND MONDAY...
STRONG GRADIENT WINDS WILL CONTINUE TO INFLUENCE THE LAKES AND UPPER
MIDWEST. THE COMBINATION OF THIS TIGHT PRESSURE GRADIENT AND COLDER
AIR SPREADING ACROSS THE WESTERN LAKES WILL RESULT IN WINDS RISING
AGAIN TO GALE FORCE ON THE LAKE FROM LATER THIS AFTERNOON INTO
MONDAY. STRONGEST WINDS WILL BE ON THE NORTHERN END OF THE LAKE
WHERE SPEEDS MAY REACH 45 KTS AT TIMES TONIGHT AND EARLY MONDAY. ON
THE FAR SOUTH END...MARGINAL GALE FORCE WINDS OF 35 KTS WILL BE MORE
LIKELY AND WILL BE OF SHORTER DURATION MAINLY DURING TONIGHT. WINDS
WILL THEN DIMINISH ACROSS THE LAKE LATE MONDAY AND TUESDAY AS THE
OLD LOW FINALLY PULLS AWAY.
BASED ON THESE TRENDS HAVE EXTENDED GALE WARNING TO THE SOUTH END
OPEN WATER ZONES THROUGH 14Z/9 AM CDT MONDAY...AND WILL MAINTAIN THE
GALE WARNING FOR THE NORTH HALF OR SO OF THE LAKE THROUGH 20Z/3 PM
CDT MONDAY.
ANOTHER AREA OF LOW PRESSURE WILL DEVELOP AND LIFT NORTH ALONG THE
EAST COAST BY MID-WEEK...WHICH WILL AGAIN TIGHTEN THE PRESSURE
GRADIENT ACROSS THE GREAT LAKES AS HIGH PRESSURE ALSO BUILDS SOUTH
ACROSS THE PLAINS.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM MONDAY.
GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ868 UNTIL 3 PM MONDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM TUESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 4 PM
MONDAY.
&&
$$
