756 PM CDT
FIRST WAVE OF SHOWERS CONTINUES TO SLOWLY WEAKEN AS IT ATTEMPTS
TO MOVE EASTWARD INTO SLIGHTLY DRIER/MORE STABLE AIRMASS. NEXT
WAVE OF SHOWERS/EMBEDDED THUNDER NEARING THE MS RIVER SHOULD MAKE
SLOW BUT STEADY PROGRESS EAST OVERNIGHT. MODELS CONTINUE TO
SUGGEST WEAK...ALBEIT SUFFICIENT...INSTABILITY TO MAINTAIN AT
LEAST A SLIGHT CHANCE OF THUNDER IN THE GRIDS OVER OUR WESTERN CWA
OVERNIGHT.
MAIN CHANGE TO GOING FORECAST WAS TO BUMP UP LOW TEMPS 1 TO 2
CATEGORIES OVER GOING FORECAST. EXTENSIVE CLOUD COVER AND
INCREASING DEWPOINTS SHOULD LARGELY PUT THE KIBOSH ON TEMPS
FALLING...SO LOWS MOST AREAS SHOULD HOLD IN THE UPPER 50S/LOWER
60S.
UPDATED GRIDS/ZFP ARE OUT.
IZZI
&&
.PREV DISCUSSION...
338 PM CDT
MAIN FORECAST CONCERNS ARE WITH PRECIP TRENDS OVER THE NEXT 24
HOURS WITH A CONTINUED SLIGHT CHANCE FOR THUNDERSTORMS...AND WITH
SLIGHTLY COOLER TEMPS GOING INTO THE END OF THE WORK WEEK.
LATEST RADAR IMAGERY DEPICTING MAIN AREA OF PRECIP WHICH HAS
STAYED JUST TO THE WEST OF THE CWA FOR THE MOST OF THIS AFTERNOON
HAS FINALLY BEGUN TO WORK ITS WAY INTO PORTIONS OF THE WESTERN
CWA. AS AN UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS AND
ATTENDANT SURFACE LOW SLOWLY PROGRESS TO THE EAST...FORCING FOR
ASCENT ALSO CONTINUES TO SLOWLY INCREASE...BUT WITH BEST FORCING
STILL REMAINING JUST OUTSIDE OF THE CWA. SLOW IS THE KEY WORD HERE
AS THIS MAIN AXIS OF PRECIPITATION HAS NOT WORKED ITS WAY EAST AS
MUCH TODAY AS WAS PREVIOUSLY FORECAST. SO HAD BROUGHT DOWN POPS
FOR THIS AFTERNOON ACROSS THE WESTERN HALF OF THE CWA...MAINLY
KEEPING CHANCE POPS FOR THE FAR WESTERN PORTION OF THE CWA. A FEW
LIGHTNING STRIKES HAVE BEEN REPORTED TODAY AS LATEST RUC ANALYSIS
CONTINUES TO INDICATE AN AXIS OF WEAK INSTABILITY EXTENDING FROM
CENTRAL WISCONSIN SOUTHWEST INTO NORTHEAST MISSOURI...WHERE
500-1000 J/KG OF MUCAPE CURRENTLY RESIDE. WITH THE MAIN AREA OF
PRECIPITATION AND CLOUD COVER STAYING JUST TO THE WEST OF THE
CWA...AREAS IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA WERE ABLE
TO RISE QUITE NICELY TODAY WITH THE HELP OF SUNNY SKIES. TEMPS
ROSE TO THE UPPER 70S TODAY ACROSS MUCH OF THE CWA WITH EVEN SOME
AREAS OVER THE SOUTHERN FRINGE OF THE CWA GETTING FAIRLY CLOSE TO
THE 80 MARK.
WILL CONTINUE THE USE OF THE WORD SLOW AS WE TRANSITION INTO
TONIGHT...AS I THINK THAT THIS EASTERLY PROGRESSION OF THE MAIN
AXIS OF PRECIP WILL NOT QUITE PUSH ALL THE WAY EAST THROUGH THE
REMAINDER OF THE FORECAST AREA...WITH THE WEST AND SOUTHWEST HALF
OF THE CWA OBSERVING THE BEST CHANCE FOR PRECIP TONIGHT. DESPITE
THE AFOREMENTIONED LONGWAVE TROUGH AND SEVERAL WAVES OF ENERGY
ROUNDING THE BASE OF THIS TROUGH...I THINK SOME INITIAL DRIER
CONDITIONS WILL PLAY MORE OF A FACTOR TONIGHT AS AN EASTERLY
COMPONENT TO THE WIND FIELD WILL HELP KEEP THIS DRIER AIR IN
PLACE. THEN FORECAST SOUNDINGS AND TIME HEIGHTS INDICATING THE
ENTIRE COLUMN TO FINALLY SATURATE CLOSER TOWARDS THE EARLY
THURSDAY MORNING TIME FRAME FOR A GOOD PORTION OF THE CWA WITH ALL
AREAS IN NORTHEAST ILLINOIS TO FINALLY OBSERVE THIS PRECIP. THE
EXCEPTIONS WILL LIKELY BE AREAS IN NORTHWEST INDIANA WHERE THE
ONSET OF PRECIP WILL CONTINUE TO BE DELAYED. THE CURRENT
INSTABILITY AXIS IS FORECAST TO ALSO SHIFT EAST WITH TIME TONIGHT
INTO EARLY THURSDAY AS THIS TROUGH OF LOW PRESSURE SHIFTS
EAST...HELPING TO ALSO BRING IN SOME HIGHER DEWPOINT AIR WITH
CURRENT OBSERVATIONS SHOWING THAT UPPER 50 DEWPOINT AIR AS NOT
THAT FAR AWAY. THUS...ALL OF THIS WILL HELP WITH THE POSSIBILITY
OF THUNDER TO BE OBSERVED ACROSS THE CWA TONIGHT INTO EARLY
THURSDAY.
THURSDAY DOES NOT APPEAR TO BE THE BEST DAY AS I HAVE SLOWED THE
PROGRESSION OF THIS PRECIP AXIS FOR THURSDAY KEEPING THE HIGHEST
POPS ALMOST OVERHEAD. THIS DUE IN PART TO THE SLOW NATURE OF THE
LONG WAVE TROUGH...AND WITH A SHARP SHORT WAVE TROUGH TO PUSH EAST
ON THE BACKSIDE OF IT. ALTHOUGH INSTABILITY WILL BE ON THE
DECREASE THROUGHOUT THE DAY...DO FEEL THERE WILL REMAIN A SLIGHT
CHANCE FOR THUNDER FOR MOST OF THE DAY AND HAVE THE GRIDS TO
REFLECT THIS. WITH THIS PRECIP AND CLOUD SHIELD AS WELL A COOLER
AIR MASS MOVING IN...TEMPS WILL BE COOLER WITH HIGH TEMPS ONLY
FORECAST TO RISE INTO THE LOW AND MID 60S.
AS THIS UPPER LEVEL TROUGH WILL CONTINUE TO BE SLOW TO
EXIT...CYCLONIC FLOW WILL REMAIN IN PLACE WITH GUIDANCE INDICATING
ANOTHER WAVE WILL SHIFT EAST ACROSS THE REGION ON FRIDAY. THIS
COINCIDING WITH STEEPENING LAPSE RATES WILL PROVIDE THE SETUP FOR
CLOUD COVER TO REMAIN AS WELL AS CHANCES FOR RAIN SHOWERS. HAVE
OPTED TO LEAVE THE MENTION OF LIGHT SHOWERS ACROSS THE CWA ON
FRIDAY...BUT FEEL THAT ANYTHING THAT DOES FALL SHOULD BE BRIEF AND
LIGHT IN NATURE.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* LINE OF WEAKENING SHRA AND ISOLATED TS TO THE WEST OF THE
TERMINALS...NOT EXPECTED TO REACH THE TERMINALS.
* A MORE SUBSTANTIAL ROUND OF SHRA ARRIVES BY 10Z.
* LOW MVFR CIGS LATE TONIGHT AND THURSDAY.
JEE
//DISCUSSION...UPDATED 00Z...
CURRENTLY...A LINE OF BROKEN SHRA LIES IN NORTH-CENTRAL IL. THE LINE
WILL CONTINUE TO WEAKEN AND STAY WEST OF THE ORD AND MDW TERMINALS.
LOW PRESSURE CURRENTLY IN IOWA WILL DRIFT EASTWARD AND
STRENGTHEN TONIGHT. CONDITIONS WILL DETERIORATE AS THE LOW MOVES
INTO THE REGION OVERNIGHT AND INTO TOMORROW. EXPECTING NEXT ROUND
OF SHRA TO HIT RFD AT 08Z...AND PROGRESS TO ORD BY 10Z. PRECIP
WILL BE PRIMARILY SHOWERS BUT A THUNDERSTORM OR TWO MAY OCCUR WITH
WEAK INSTABILITY ALOFT...HOWEVER NOT ENOUGH CONFIDENCE OR
INSTABILITY TO PUT TS OR CB IN TAFS. MODELS ARE HINTING THAT THERE
WILL BE TWO WAVES OF SHOWERS TOMORROW. THE FIRST WILL BE THROUGH
THE AREA BY 23Z. KEPT VCSH IN THE TAF TO REFLECT LINGERING SHOWERS
OR A SHORTER BREAK IN SHOWERS THAN CURRENTLY INDICATED. THE SECOND
ROUND OF SHOWERS WILL HIT ORD BY 14/02Z. SHOWERS WILL BE EAST OF
ALL TERMINALS BY 14/06Z. MVFR VSBY WILL OCCUR WITH THE HEAVIEST
SHOWERS.
FOR CIGS...BKN080-BKN050 CIGS ASSOCIATED WITH THE LINE OF SHRA IN
NORTH CENTRAL IL WILL STICK AROUND THROUGH 10Z. AS THE LOW
APPROACHES...CIGS WILL DROP TO MVFR BY 12Z. DECIDED TO BE
OPTIMISTIC AND GO WITH SCT006 BKN012 CIGS FOR ALL TERMINALS DURING
THE FIRST ROUND OF SHOWERS. WHILE THE LOW WILL PASS OVERHEAD
TOMORROW...OBS FROM TERMINALS CURRENTLY UNDERNEATH THE LOW ARE LOW
MVFR OR BETTER. HOWEVER...PUT SCT006 IN THE GROUPS TO INDICATE
THERE IS A POSSIBILITY THAT CIGS WILL BE LOWER THAN CURRENTLY
FORECASTED. CIGS WILL SLOWLY IMPROVE AFTER 14/02Z WHEN THE SHRA
ARE EAST OF ALL TERMINALS.
FOR WINDS...MAY SEE A BRIEF SHIFT FROM SE TO SW OR W IN THE NEXT FEW
HOURS AS THE LINE OF SHOWERS PASSES THROUGH THE CWA. THE WIND SHIFT
WILL BE BRIEF...AND THEREFORE NOT INDICATED IN THE TAFS. WINDS WILL
BE SE LESS THAN 10 KT OVERNIGHT AND TOMORROW...BECOMING VRB04KT
BEHIND THE FIRST WAVE OF SHOWERS. STRONG NW WINDS WILL MOVE INTO
THE AREA BEHIND THE COLD FRONT.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM CONFIDENCE IN TIMING OF PRECIP ONSET LATE TONIGHT...HIGH
CONFIDENCE IN INCREASING COVERAGE.
* MEDIUM CONFIDENCE IN CIG FORECAST.
* HIGH CONFIDENCE IN WIND FORECAST.
JEE
//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...
243 PM CDT
A LOW PRESSURE COMPLEX EXTENDING FROM FAR SOUTHERN MANITOBA TO
THE LOWER MO RIVER VALLEY WILL STRENGTHEN AS IT MOVES EAST TO
WESTERN ONTARIO...WI AND IL OVERNIGHT. THE LOW WILL CONTINUE TO
DEEPEN AS IT MOVES E ACROSS LAKE MICHIGAN THU AND THU EVE.
A STRONG NW FLOW OF MUCH COOLER AIR FROM NORTHER CANADA WILL BE
USHERED SOUTHEASTWARD ACROSS THE UPPER GREAT LAKES IN THE WAKE OF
THE LOW. DUE TO THE STRENGTH OF THE LOW AND THE COLD AIR ADVECTION
NW GALES OF AROUND 35 KT ARE A GOOD BET FOR FRI INTO SAT.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...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.
&&
$$
