342 PM CDT
MAIN FORECAST CONCERNS ARE WITH PRECIP TRENDS LATE THIS AFTERNOON
INTO THE EVENING...BEFORE THIS MAIN AREA OF PRECIPITATION FINALLY
SHIFTS OUT OF THE AREA LATER TONIGHT.
LATEST RADAR IMAGERY SHOWING A LARGE AREA OF PRECIP EXTENDING
ACROSS MUCH OF THE CWA LATE THIS AFTERNOON...WHICH HAS BEEN THE
CASE FOR MUCH OF THE DAY. THIS IS ONGOING AS THE CURRENT LONGWAVE
TROUGH CONTINUES TO EXTEND ACROSS THE ENTIRE REGION WITH SEVERAL
EMBEDDED WAVES OF ENERGY ROUNDING THE BASE. WITH THIS IN
PLACE...LATEST SATELLITE IMAGERY DEPICTING A STRONG/SHARPER SHORT
WAVE TROUGH CONTINUING TO PUSH EAST ACROSS THE MIDWEST. WITH THIS
TROUGH SHIFTING EAST THROUGH THE LARGER SCALE TROUGH...A
SHEAR/DEFORMATION ZONE HAS DEVELOPED AND HELPED TO MAINTAIN
STRONGER AREAS OF SHOWERS OVER NORTHEAST ILLINOIS. THIS LARGER
AREA OF MORE MODERATE RAINFALL HAS NOW SHIFTED EAST/NORTHEAST OVER
THE LAKE AND NORTHWEST INDIANA...AND WILL CONTINUE THIS MOVEMENT
INTO THE EVENING. AS THIS HAS OCCURRED TODAY...SOME DRIER ALOFT
MOVED THROUGH NORTHERN ILLINOIS INITIALLY DRYING CONDITIONS ACROSS
THE FAR WESTERN CWA. ALTHOUGH SINCE THEN...THIS DRIER HAS HELPED
THIS AREA BECOME MORE CONVECTIVELY UNSTABLE. THIS COINCIDING WITH
STEEPENING LOW LEVEL LAPSE RATES IN TURN HELPED WITH THE
DEVELOPMENT OF SHOWERS ACROSS THIS AREA THIS PAST AFTERNOON...WITH
LATEST RADAR IMAGERY SHOWING THESE MORE CONVECTIVE ELEMENTS
SHIFTING EAST THROUGH NORTH CENTRAL ILLINOIS. ALTHOUGH WE HAVE
BECOME MORE UNSTABLE...WITH VERY LITTLE INSTABILITY TO STILL WORK
WITH...THUNDER HAS BEEN NONEXISTENT AND FEEL THAT THIS WILL
CONTINUE AS CONDITIONS BECOME LESS FAVORABLE LATER THIS EVENING.
EXPECT THIS PRECIP TO CONTINUE TO SHIFT EAST THROUGH THE REMAINDER
OF THE AFTERNOON AND EARLY EVENING BEFORE A GRADUAL DRYING TREND
BEGINS TO OCCUR. THIS WILL OCCUR AS MAIN AXIS OF
PRECIPITATION...DUE TO LARGE/SYNOPTIC SCALE FORCING...SHIFTS EAST
OUT OF THE REGION AND CONDITIONS BECOME LESS FAVORABLE DIURNALLY.
WITH PRECIP ENDING FROM WEST TO EAST AND CLOUD COVER SHIFTING
EAST...SKIES WILL CLEAR THIS EVENING. ALTHOUGH LOOKING UPSTREAM
ACROSS THE PLAINS...ADDITIONAL WAVES OF ENERGY CAN BE OBSERVED
DROPPING SOUTH/SOUTHEAST WITH ASSOCIATED MID AND HIGH LEVEL CLOUD
COVER. DISTANCE SPEED TOOL AND LATEST SHORT RANGE GUIDANCE
INDICATE THAT THESE MID LEVEL FEATURES WILL SHIFT THROUGH THE
REGION TONIGHT. DONT FEEL THERE IS ANY THREAT OF ADDITIONAL
SHOWERS...BUT THERE COULD BE SOME ADDITIONAL CLOUD COVER WHICH
COULD SPILL OVER THE ALREADY CLEARING SKIES.
AS THIS UPPER LEVEL TROUGH CONTINUES TO DIG SOUTHEAST ACROSS THE
REGION ON FRIDAY...IT WILL BEGIN TO CLOSE ITSELF OFF AND STICK
AROUND THE AREA INTO THE START OF THE WEEKEND. THIS WILL HELP TO
MAINTAIN CYCLONIC FLOW ACROSS THE AREA AND A STREAM OF COOLER
AIR...WHICH WILL HELP WITH STRATOCU DEVELOPMENT ON FRIDAY AND
COOLER HIGH TEMPS. ALTHOUGH I HAVE REMOVED ANY MENTION OF SHOWERS
FOR FRIDAY...THATS NOT TO SAY A FEW SPRINKLES MIGHT BE OBSERVED AS
LOW LEVEL LAPSE RATES STEEPEN ONCE AGAIN.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* LINE OF SHRA MOVING THROUGH TERMINALS NOW...SHOWERS WILL BE EAST
OF TERMINAL BY 2330Z.
* GUSTY WEST WINDS UP TO 23KT MOVING IN WITH LINE OF SHOWERS.
EXPECTING GUSTS TO DISSIPATE BY 2330Z AS THE SUN SETS AND MIXING
IS REDUCED.
* SCT MVFR CIGS MOVING ALONG WITH LINE OF PRECIP...WILL BE EAST OF
TERMINALS BY 2330Z. CIGS IMPROVING TO VFR SHORTLY THEREAFTER.
* GUSTY WEST WINDS RETURN FRIDAY MORNING...GUSTS UP TO 35 KT POSSIBLE.
JEE
//DISCUSSION...UPDATED 18Z...
MAIN WEATHER ISSUES WILL BE CIG TRENDS THIS
AFTERNOON...INCREASING WINDS LATE THIS AFTERNOON AND AGAIN ON
FRIDAY...AND VISIBILITIES IN AND OUT OF SCATTERED RAIN SHOWERS.
LOW PRESSURE AND AN ASSOCIATED FRONTAL ZONE...IS CURRENTLY PUSHING
ACROSS NORTHEASTERN ILLINOIS. CIG TRENDS HAVE BEEN A BEAR THIS
MORNING WITH CIGS COVERING NEARLY ALL OF THE IMPORTANT FLIGHT
CATEGORIES (RANGING FROM IFR TO VFR). LOW VFR TO OCCASIONAL MVFR
CIGS HAVE DOMINATED AT KORD AND AND KMDW FOR THE PAST FEW HOURS NOW.
HOWEVER...LOWER CLOUDS AROUND 1,000 FEET HAVE SLOWLY BEEN PUSHING
EAST ACROSS NORTHERN ILLINOIS BEHIND THE FRONTAL BOUNDARY.
THEREFORE...ALTHOUGH THESE LOW CLOUDS HAVE BEEN TAKING THERE TIME
MOVING BACK ACROSS NORTHEASTERN ILLINOIS...I EXPECT CIGS TO LOWER
INTO THE LOW MVFR RANGE (AROUND 1,200 FT AGL) THROUGH AT LEAST MID
AFTERNOON. BRIEF PERIODS OF IFR CIGS ARE POSSIBLE AS WELL OVER THE
NEXT COUPLE OF HOURS.
SCATTERED SHOWERS WILL CONTINUE FOR THE NEXT FEW HOURS AS AN UPPER
LEVEL DISTURBANCE CONTINUES TO GENERATE FORCING FOR PRECIPITATION. A
FEW OF THE HEAVIER SHOWERS MAY PRODUCE BRIEF PERIODS OF MVFR VIS.
HOWEVER...AS WE HEAD THROUGH THE AFTERNOON NORTHWESTERLY WINDS WILL
BE ON THE INCREASE ALONG THE BACK SIDE OF THE SURFACE LOW. I EXPECT
WINDS TO GUST UP TO 20 KT AT THIS LATE THIS AFTERNOON BEFORE THE
WIND GUSTS ABATE AFTER SUNSET. THESE STRONGER WINDS SHOULD HELP
IMPROVE THE CIGS AS THE ATMOSPHERE MIXES SOME DRIER AIR ACROSS THE
AREA.
EVEN STRONGER WINDS ARE EXPECTED TOMORROW AS THE SURFACE LOW
RAPIDLY DEEPENS ACROSS THE UPPER GREAT LAKES. THIS SHOULD SUPPORT
WESTERLY WINDS WITH GUSTS AROUND 30 KT FRIDAY AFTERNOON. VFR
CONDITIONS ARE EXPECTED ON FRIDAY...WITH A SCT-BKN DECK OF STRATO CU
EXPECTED IN THE AFTERNOON.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM CONFIDENCE WITH CIG HEIGHTS...HIGH CONFIDENCE WITH CIG TRENDS.
* MEDIUM CONFIDENCE WITH DURATION OF WIND GUSTS THIS EVENING.
* HIGH CONFIDENCE WITH STRONG WESTERLY FLOW ON FRIDAY.
JEE
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...LINGERING SHOWER POSSIBLE DURING THE EVENING...BREEZY...VFR.
SATURDAY...VFR.
SUNDAY THROUGH TUESDAY...VFR WITH PERIODIC RAIN CHANCES...SOME
MVFR POSSIBLE.
WEDNESDAY...VFR.
MDB
&&
.MARINE...
245 PM CDT
PERIOD OF WEST TO NORTHWEST GALES ARE EXPECTED ACROSS LAKE MICHIGAN
FROM LATER TONIGHT THROUGH MUCH OF SATURDAY AS LOW PRESSURE
CURRENTLY OVER WISCONSIN AND FAR SOUTHERN LAKE MICHIGAN DEEPENS
SIGNIFICANTLY WHILE LIFTING NORTHEAST TO NEAR JAMES BAY. FORECAST
SOUNDINGS FROM VARIOUS NUMERICAL MODELS INDICATE FREQUENT GUSTS
RISING INTO THE 40-45 KT RANGE DURING THE PERIOD...BEFORE GRADUALLY
TAILING OFF LATE SATURDAY/SATURDAY NIGHT AS THE LOW PULLS FARTHER
AWAY.
BASED ON THIS HAVE ELECTED TO HOIST GALE WARNINGS FOR THE OPEN
WATERS...BEGINNING LATE TONIGHT ON THE SOUTH HALF...AND EARLY FRIDAY
MORNING FARTHER NORTH AS WINDS ARE EXPECTED TO INCREASE FROM SOUTH
TO NORTH FOLLOWING THE TRACK OF THE LOW.
HEADLINES IN THE IL/IN NEARSHORE WATERS OF SOUTHERN LAKE MICHIGAN A
LITTLE TRICKIER...WITH WINDS INCREASING ENOUGH FOR SMALL CRAFT
ADVISORY CONDITIONS PRIOR TO THE START OF GALE FORCE WINDS TONIGHT.
THUS WILL HAVE AN SCA FOR THE NEARSHORE ZONES BEGINNING AT 06Z
TONIGHT...WITH GALES DEVELOPING MIDDAY FRIDAY.
CONDITIONS WILL STEADILY IMPROVE SATURDAY NIGHT INTO SUNDAY AS THE
LOW PULLS AWAY...AND WEAK HIGH PRESSURE SPREADS SOUTHEAST FROM THE
NORTHERN PLAINS.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...1 AM FRIDAY TO 1 PM FRIDAY.
GALE WARNING...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...1 PM
FRIDAY TO 1 PM SATURDAY.
GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ868...7 AM FRIDAY TO 1 AM SUNDAY.
GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...4 AM FRIDAY TO 1 AM
SUNDAY.
&&
$$
