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 10Z...
* RAIN CONTINUING INTO THE AFTERNOON WITH MOST WIDESPREAD COVERAGE
THROUGH THE MORNING...VISIBILITY GENERALLY 3-5 SM IN THE RAIN
THOUGH 2SM POSSIBLE AT TIMES.
* SOUTHEAST WINDS TURNING EAST OR NORTHEAST AFTER DAYBREAK WITH
VARIABLE WINDS POSSIBLE EARLY AFTERNOON AS LOW PRESSURE MOVES
OVERHEAD OR JUST TO THE SOUTH. WINDS THEN TURN NORTHWEST AND
INCREASE MID/LATE AFTERNOON AS A COLD FRONT PASSES.
* EXPECT MAINLY IFR CIGS INTO EARLY AFTERNOON WITH LOWEST CIGS
LIKELY 600-800 FT...BRIEF IMPROVEMENT TO MVFR POSSIBLE AT
TIMES...WITH STEADY IMPROVEMENT TO MVFR EARLY AFTERNOON.
* LOW CHANCE FOR EMBEDDED THUNDERSTORMS.
MDB
//DISCUSSION...UPDATED 08Z...
SHOWER COVERAGE CONTINUES TO INCREASE ACROSS NORTHEAST ILLINOIS
AND NORTHWEST INDIANA WITH LARGE SHIELD OF RAIN ACROSS CENTRAL
ILLINOIS. CIGS REMAIN VARIABLE BUT MVFR IS BECOMING MORE
WIDESPREAD UPSTREAM WITH AREAS OF IFR AS WELL. HOWEVER...VARIABILITY
WILL LIKELY CONTINUE THROUGH THE MORNING COMPLICATING TAF DETAILS.
REGIONAL RADAR MOSAIC SHOWS DRYING ACROSS FAR WESTERN IL AND
EASTERN IA CLOSE TO THE CENTER OF LOW PRESSURE. LATEST TRENDS
SUPPORT THIS MOVING INTO RFD IN A FEW HOURS THOUGH SOME ADDITIONAL
DEVELOPMENT MAY COMMENCE. HAVE PULLED BACK ON THE RAIN INTENSITY
AND VISIBILITY REDUCTION AT RFD AFTER DAYBREAK THOUGH CIGS WILL
LIKELY REMAIN VARIABLE MVFR/IFR. WIND DIRECTION FORECAST REMAINS
CHALLENGING WITH THE LOW BEING RATHER BROAD BUT STARTING TO
CONSOLIDATE.
FROM 06Z...
LOW PRESSURE CONTINUES TO BETTER ORGANIZE ACROSS EASTERN IOWA AND
WESTERN ILLINOIS WHILE MOVING SLOWLY EASTWARD. BANDS OF SHOWERS
CONTINUE TO MOVE NORTHWARD ACROSS NORTH CENTRAL ILLINOIS AND ARE
NOW MOVING INTO THE CHICAGO METRO AREA. CIGS ARE A MIX OF MVFR/VFR
WITH SOME IFR IN SPOTS. THE LOW WILL INTENSIFY THROUGH THURSDAY
MORNING AS IT TRACKS EASTWARD. AS THIS OCCURS RAIN SHOULD BECOME
MORE WIDESPREAD ACROSS THE TERMINALS WITH EMBEDDED THUNDER
POSSIBLE. CEILINGS WILL LIKELY REMAIN RATHER VARIABLE FOR THE REST
OF THE NIGHT BUT EXPECT THAT MORE SOLID MVFR AND AREAS OF IFR WILL
DEVELOP AS THE RAIN BECOMES MORE WIDESPREAD TOWARD DAYBREAK.
VISIBILITY WILL ALSO VARY WITH PRIMARILY MVFR IN RAIN BUT IFR
PERIODS WILL BE POSSIBLE UNDER HEAVIER EMBEDDED AREAS.
THUNDERSTORMS MAY ALSO BE EMBEDDED BUT CONFIDENCE IN HOW NUMEROUS
THEY WILL BE OR WHEN EXACTLY THEY MAY AFFECT A GIVEN TERMINAL IS
LOW...THE COULD OCCUR AT JUST ABOUT ANY TIME BETWEEN NOW AND
THURSDAY AFTERNOON.
THE PASSAGE OF THE LOW WILL CAUSE HAVOC WITH THE WIND FORECAST AS
IT WILL BE PASSING OVER OR CLOSE TO EACH OF THE TERMINALS.
FORECAST GUIDANCE IS MIXED ON WHETHER IT MOVES JUST TO THE SOUTH
OR RIGHT OVERHEAD INTO THURSDAY AFTERNOON. SOUTHEASTERLY WINDS
WILL TURN MORE EASTERLY THEN PROBABLY END UP LIGHT AND VARIABLE
DURING THE MORNING AS THE LOW MOVES ACROSS. RFD WILL BE THE
EXCEPTION AS THEY SHOULD TURN NORTH OR NORTHWESTERLY MORE QUICKLY
THIS MORNING. ONCE THE LOW AND AN ASSOCIATED COLD FRONT PASS
DURING THE AFTERNOON WINDS WILL SHIFT TO THE WEST-NORTHWEST OR
NORTHWEST AND INCREASE IN SPEED. RAIN SHOWERS WILL COME TO AN END
AS THE FRONT PASSES FROM WEST TO EAST DURING THE LATE AFTERNOON OR
EARLY EVENING WITH CEILINGS AND VISIBILITY ALSO IMPROVING INTO
EARLY EVENING. WILL NEED TO WATCH THE TIMING OF THIS AS THIS
SYSTEM HAS BEEN A SLOW ONE SO IMPROVEMENT MAY NEED TO BE SLOWED
SLIGHTLY WITH LATER ISSUANCES.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 10Z...
* HIGH CONFIDENCE THAT BULK OF THE RAIN WILL BE THIS MORNING WITH
LESS WIDESPREAD RAIN THIS AFTERNOON.
* MEDIUM CONFIDENCE SOUTHEAST WINDS BECOMING EASTERLY THIS MORNING
THEN VARIABLE EARLY AFTERNOON...HIGH CONFIDENCE IN WINDS
SHIFTING WEST-NORTHWEST MID/LATE AFTERNOON WITH COLD FRONT.
* MEDIUM-HIGH CONFIDENCE THAT MAINLY IFR CIGS WILL CONTINUE THROUGH
THE MORNING...LOW-MEDIUM CONFIDENCE IN IFR POTENTIAL THIS
AFTERNOON.
* LOW CONFIDENCE THAT THUNDERSTORMS WILL OCCUR AND WHEN EXACTLY
THEY MIGHT...COULD BE ANYTIME FROM DAYBREAK INTO MID AFTERNOON.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...SHOWERS...MVFR...AND POSSIBLE IFR IN THE MORNING. STRONG
NW WINDS BEHIND THE COLD FRONT.
SATURDAY...VFR.
SUNDAY THROUGH TUESDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.
JEE
&&
.MARINE...
320 AM CDT
POTENT AREA OF LOW PRESSURE WILL STEADILY DEEPEN TODAY ACROSS
NORTHEAST ILLINOIS LIFTING NORTHEAST ACROSS SOUTHERN LAKE
MICHIGAN...THEN CONTINUING TO LIFT NORTH/NORTHEAST ACROSS LOWER
MICHIGAN. THE PRESSURE GRADIENT IS EXPECTED TO RAPIDLY TIGHTEN ON
THE BACK SIDE OF THIS LOW PRESSURE LATE TONIGHT...ALLOWING WINDS
TO STEADILY INCREASE FROM 10 TO 20 KT...TO NEAR GALE CRITERIA BY
EARLY FRIDAY MORNING. GUIDANCE CONTINUES TO LEAN TOWARDS GALES TO
40KT PRIMARILY FOR THE OPEN WATERS PORTION OF LAKE MICHIGAN. ALONG
THE NEARSHORE WATERS OF ILLINOIS AND NORTHWEST INDIANA IT APPEARS
WINDS WILL HOVER BETWEEN 25 AND 30 KT. THUS HAVE HOISTED A SMALL
CRAFT ADVISORY FOR THOSE NEARSHORE WATERS. IT IS POSSIBLE THAT A
FEW GUSTS TO GALE CRITERIA MAY BE OBSERVED IN THE NEARSHORE
WATERS...HOWEVER CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO
HOIST A GALE WATCH FOR THE NEARSHORE WATERS. LATER SHIFTS MAY NEED
TO MAKE AN ADJUSTMENT IF NEW GUIDANCE INDICATES FURTHER
STRENGTHENING OF THE LOW PRESSURE.
ELEVATED WINDS/WAVES ARE EXPECTED TO PERSIST THROUGH FRIDAY NIGHT
AND INTO EARLY SATURDAY...BEFORE THE PRESSURE GRADIENT BEGINS TO
SLACKEN SATURDAY AFTERNOON. WITH THE PERSISTING NORTHWEST WINDS
AND MUCH COOLER AIR TRAVELING OVER THE LAKE...WAVES WILL REMAIN
ELEVATED DESPITE THE DIMINISHING WINDS. THUS HAVE HELD ONTO THE
SMALL CRAFT ADVISORY FOR THE NEARSHORE WATERS THROUGH SATURDAY
AFTERNOON FOR THE ILLINOIS NEARSHORE. SLIGHTLY LATER FOR THE
INDIANA NEARSHORE.
ANOTHER POTENT LOW PRESSURE SYSTEM IS POISED TO TRAVERSE THE GREAT
LAKES REGION EARLY NEXT WEEK. GUIDANCE CONTINUES TO BE FOCUSED ON
A LATE MON THROUGH TUE TIMEFRAME.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ744-LMZ745...1 AM FRIDAY TO 10 PM
SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...10 AM
FRIDAY TO 4 PM SATURDAY.
GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM FRIDAY TO NOON
SATURDAY.
&&
$$
