340 AM CDT
THE END IS UPON US...AND THAT END IS THE ENDLESS SUMMER-LIKE
CONDITIONS THAT HAD BECOME THE NORM FOR THE LAST FEW WEEKS. THE
CHANGES WILL INCLUDE THE SHOWERS TODAY...CHANCES AGAIN TOMORROW
AND AGAIN ON SUNDAY...COUPLED WITH CHILLIER TEMPERATURES THROUGH
THE WEEKEND AND INTO THE WORK WEEK.
THIS MORNING...WATER VAPOR IMAGERY AND PROFILER ANALYSIS SHOW A
LARGE TROUGH TRAVERSING THE PLAINS. DIVING SOUTHEAST ALONG THE
WESTERN FLANK OF THE TROUGH AND THROUGH EASTERN NEBRASKA IS A FAIRLY
POTENT SHORTWAVE...BUT THAT WILL HAVE MORE OF A TRIGGER ON WEATHER
SOUTH ACROSS THE LOWER MISSISSIPPI VALLEY TODAY. ACROSS OUR NECK OF
THE WOODS...A WEAK SURFACE LOW IS NOTED ALONG THE ILLINOIS/IOWA AND
WISCONSIN BORDERS. EXTENDING SOUTH OF THIS LOW IS A COLD FRONT THAT
DRAPES SOUTH TO EASTERN TEXAS. BOTH OF THESE FEATURES WILL CONTINUE
TO SLOWLY PUSH EAST AND ACROSS THE CWA THROUGH THE DAY. FULLY EXPECT
THE JUMBLED MESS OF SHOWERS TO CONTINUE THROUGH THE MORNING HOURS
AND INCREASE BEFORE SLOWLY COMING TO AN END FROM WEST TO EAST
THROUGH THE AFTERNOON. ENDED UP PULLING OUT THE MENTION OF THUNDER
FROM THE GOING FORECAST THIS MORNING AS FORECAST SOUNDINGS ARE
SHOWING NARY A GASP OF INSTABILITY TO WORK WITH. SPC MESOSCALE
ANALYSIS SHOWS THE BETTER AXIS OF INSTABILITY TO THE SOUTH AND
ACROSS CENTRAL ILLINOIS...WITH MAYBE 100 J/KG OF MUCAPE NOSING
INTO THE SOUTHERN THIRD OF THE CWA. AS THE AFOREMENTIONED TROUGH
SHIFTS TO THE EAST...WITH SURFACE LOW AND FRONT MOVING TO THE EAST
AS WELL...COULD ARGUE THAT IF THERE WAS ANY CHANCE FOR THUNDER
TODAY IT WOULD BE GENERALLY EAST OF I-57 AND SOUTH OF
I-80...HELPING TO ADVECT IN HIGHER DEWPOINT AIR. BUT GIVEN THE
LIMITED INGREDIENTS TO WORK WITH...WILL KEEP ANY WORDING OUT.
UPPER LEVEL TROUGH WILL MOVE EAST THROUGH THE DAY TODAY AND
LINGERING CLOUDS PRECIP AND CLOUDS WILL KEEP TEMPERATURES
DOWN...WITH MOST LOCATIONS ONLY SEEING SOME INCREASE OVER THE
MORNING READINGS. STRONGER NORTHWEST WINDS WILL THEN BE ON THE
INCREASE OVERNIGHT BRINGING IN A COOLER AIRMASS BY FRIDAY WITH
CYCLONIC FLOW REMAINING IN PLACE THROUGH THE WEEKEND. MAINTAINED THE
MENTION OF LIGHT SHOWERS AGAIN TOMORROW AS ANOTHER WAVE RIPPLES
THROUGH THE FLOW. LAPSE RATES TO REMAIN STEEP /ON THE ORDER OF
6.5C/KM OR GREATER FROM THE SURFACE THROUGH THE MID LEVELS/.
MOISTURE AVAILABILITY AND FORCING IS NOT THAT STRONG AND ANYTHING
THAT DOES MANAGE TO FORM AND FALL...SHOULD BE LIGHT AND BRIEF.
WITH THE STEEP LAPSE RATES AND EFFICIENT MIXING...EXPECT WINDS TO
BE THE BIGGEST FEATURE/NUANCE TOMORROW...WITH MOST AREAS SEEING
GUST INTO THE 20 TO 30 MPH RANGE BY THE AFTERNOON.
THE OPENING OF THE WEEKEND SHOULD DRY AND A FEW DEGREES WARMER THAN
FRIDAY AS RIDGING BUILDS IN FROM THE WEST. BY SUNDAY A MID LEVEL
BAROCLINIC ZONE WILL TIGHTEN ACROSS WISCONSIN AND SLOWLY SHIFT
SOUTHEAST...COINCIDENT WITH A WEAKENING SURFACE LOW THAT WILL
SLIDE ACROSS THE UPPER MISSISSIPPI VALLEY. CHANCES FOR LIGHT
SHOWERS WILL AGAIN LOOM IN THAT TIMEFRAME BEFORE CLEARING OUT BY
THE EVENING HOURS.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* CIG AND VIS TRENDS INTO THIS AFTERNOON...WITH LOW MVFR CIGS
MOVING BACK ACROSS THE TERMINALS.
* WINDS...WESTERLY FLOW INCREASING AND BECOMING GUSTY THIS
AFTERNOON IN THE WAKE OF THE SURFACE LOW.
* STRONG WESTERLY WINDS ON FRIDAY.
KJB
//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 18Z...
* MEDIUM CONFIDENCE ON CIG TRENDS LATER THIS AFTERNOON WITH LOW
END MVFR CIGS SETTING UP AFTER 19 UTC.
* HIGH CONFIDENCE ON WEST NORTHWESTERLY FLOW INCREASING THIS AFTERNOON IN
THE WAKE OF THE SURFACE LOW.
* HIGH CONFIDENCE ON STRONG WESTERLY FLOW ON FRIDAY.
KJB
//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...LMZ744-LMZ745...1 AM FRIDAY TO 1 PM
FRIDAY.
GALE WARNING...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...1 PM
FRIDAY TO 1 PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...10 AM
FRIDAY TO 1 PM FRIDAY.
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.
&&
$$
