344 AM CST
EARLY THIS MORNING THE LLVL VORT MAX CONTINUES TO LIFT NORTHEAST
TOWARDS HUDSON BAY. A TRAILING FRONTAL BOUNDARY STRETCHED FROM
NORTHERN LOWER MICHIGAN SOUTHWEST THROUGH NORTHERN IL...INTO
NORTHERN MO. THIS BOUNDARY WILL TRANSITION INTO A QUASI-STATIONARY
BOUNDARY OVER THE NEXT 24HR AND BE OVER THE OHIO VALLEY BEFORE
LIFTING NORTH. IR IMAGERY EARLY THIS MORNING ALSO INDICATES
CONSIDERABLE CLOUDS STRETCHING ALONG THE FRONTAL BOUNDARY...WITH A
STEADY SURGE OF LOW/MID LVL MOISTURE ACROSS MISSOURI STRETCHING
SOUTH THROUGH NORTHERN TEXAS. WITH THE ABUNDANCE OF CLOUD COVER
OVERNIGHT...TEMPERATURES HAVE REMAINED MILD IN THE LOW/MID 50S
ACROSS MUCH OF NORTHERN/CENTRAL IL. A SLUG OF PRECIP HAS
OVERSPREAD PORTIONS OF CENTRAL IL EARLY THIS MORNING AND CONTINUES
TO SLIDE EAST. BASED ON THE IR/WATER VAPOR IMAGERY...ANOTHER SLUG
OF MOISTURE WAS OVER OK/AR/MO AND STREAMING NORTH/NORTHEAST.
SREF 850MB V-WIND...OR MOISTURE TRANSPORT...INDICATES THAT THE FEED
OF MOISTURE WILL CONTINUE TO LIFT NORTH/NORTHEAST THIS MORNING AND
SHOULD PUSH OVER THE SOUTHERN CWFA AND PORTIONS OF NORTHWEST
INDIANA. LATER THIS AFTN AN ANOMALOUS EASTERLY LLVL JET AT 850MB IS
PROGGED TO DEVELOP ACROSS THE CENTRAL PLAINS...STRETCHING EAST LATE
THIS AFTN EARLY EVE INTO PORTIONS OF IOWA/NORTHERN IL.
TEMPERATURES TODAY WILL REMAIN MILD WITH THE ALREADY MILD START...IN
THE UPPER 50S TO AROUND 60 DEGREES. FAR NORTHWEST PORTIONS OF THE
CWFA SHOULD REMAIN DRY THRU MUCH OF THE DAY TODAY.
TONIGHT THROUGH WEDNESDAY...
ANTI-CYCLONIC FLOW ACROSS THE UPPER MIDWEST ELONGATES AND STRETCHES
EAST THROUGH NEW ENGLAND. TO THE SOUTH OF THIS FEATURE IS THE
QUASI-STATIONARY BOUNDARY THAT WILL SERVE AS A FOCAL POINT OVER THE
NEXT 36 HOURS FOR A STEADY MOISTURE FEED AND POTENTIAL FOR
CONVECTION. THE PREVIOUSLY MENTIONED ANOMALOUS LLVL EASTERLY
JET...U-WIND OF 3 SIGMA...PROGGED BY THE SREF MEMBERS SHOULD
DISSOLVE BY 06Z TUE AS THE V-WIND COMPONENT INDICATES A
STRENGTHENING MOISTURE TRANSPORT INTO OUR REGION. THIS COUPLED WITH
PWAT VALUES AT 3 TO 4 SIGMA OR AROUND 1.5 INCHES...ALONG WITH VERY
MINIMAL SPREAD AMONGST ENSEMBLES/OPERATIONAL MEMBERS...INDICATES
PRECIP IS ALMOST A SURE BET. ONE CONCERN WILL BE THE PRECISE TIMING
AND PLACEMENT OF THE BOUNDARY AND TRACK OF THE SHORTWAVE. CURRENT
SOLUTIONS HAVE THE VORT TAKING A PATH THROUGH MISSOURI AND LIFTING
NORTHEAST THROUGH CENTRAL LAKE MICHIGAN WED AFTN. IF THE DOWNSTREAM
RIDGE OVER THE MID-ATLANTIC REGION CAN MAINTAIN THE CURRENT STRENGTH
THAT MAY AID IN STEERING THIS SYSTEM FURTHER NORTHWEST. DESPITE
GETTING CLOSER IN TIME...MODELS ARE EXPECTED TO SHOW SOME
CORRECTIONS OVER THE NEXT 12 TO 18 HOURS BEFORE FINALLY GETTING A
GOOD HANDLE ON THE PRECISE PATH.
WITH THE CURRENT AND EXPECTED PATH ELEVATED INSTABILITY LOOKS
PROBABLE. GUIDANCE CONTINUES TO SUGGEST A STRONG CORE OF WINDS AT
850MB PUSHING NEARLY 50KTS TUE. WITH MINIMAL BREAKS IN THE CLOUD
SHIELD...EXPECT ANY CONVECTION TO BE ELEVATED AND REMAIN JUST A
CHANCE. WITH THE EXPECTED FORCING/DYNAMICS...IT WAS PRUDENT TO LEAVE
MENTION OF THUNDER IN THE GOING FORECAST FOR TUE.
500MB TROUGH AXIS CONTINUES TO PIVOT EAST ACROSS IOWA LATE TUE NIGHT
AS THE SFC LOW STEADILY LIFTS NORTHEAST OVER THE SOUTHERN THIRD OF
LAKE MICHIGAN. AS MENTIONED EARLIER...SOME CORRECTIONS TO THE
PRECISE PATH OF THE SFC LOW WILL CONTINUE TO CORRECT. GUIDANCE ALSO
CONTINUES TO INDICATE A DEVELOPING DRY-SLOT AND MAY AID IN BRINGING
AND END TO PRECIP SLIGHTLY EARLIER EARLY WED MORNING FROM WEST TO
EAST AS THE COLD FRONT PUSHES EAST. 850MB THERMAL TROUGH ARRIVES WED
MORNING WITH TEMPS ALOFT FALLING INTO THE -3 TO -6 DEG RANGE.
ISALLOBARIC PRES CHG LOOKS FAVORABLE FOR BREEZY CONDS. WITH
CONSIDERABLE CLOUDS THROUGH MUCH OF WED BEFORE MUCH DRIER AIR
ARRIVES...TEMPS WILL NOT CHANGE MUCH. THUS HAVE OPTED TO NOT UTILIZE
A DIURNAL CURVE. EXPECT TEMPS TO BEGIN FALLING BY MIDDAY POSSIBLY
EARLY AFTN WED INTO THE LOW/MID 40S.
ENOUGH DRY AIR SHOULD BE IN PLACE ACROSS THE LAND
LOCATIONS...HOWEVER OVER LAKE MICHIGAN THE LAKE SFC/850MB TEMP
DIFFERENCE SHOULD BE LARGE ENOUGH TO ALLOW THE FORMATION OF LAKE
INDUCED CLOUDS PRECIP. TEMPS MAY EVEN BE COOL ENOUGH TO ALLOW WET
SNOW TO MIX WITH RAIN.
AS COLD AIR CONTINUES TO POUR INTO THE CWFA WED
EVENING...TEMPERATURES OVERNIGHT WILL FALL INTO THE LOWER 30S WITH A
FEW LOCATIONS IN THE UPPER 20S.
THURSDAY THROUGH SUNDAY...
ENSEMBLES CONTINUE TO INDICATE A RATHER HIGH CONFIDENCE IN THE
EXTENDED PERIODS WITH RESPECT TO A TROUGH PIVOTING EAST THROUGH THE
GREAT LAKES REGION...STRETCHING SOUTH THROUGH THE TENNESSEE VALLEY
THURSDAY. FURTHER UPSTREAM TOWARDS THE PAC-NW...A POTENT 500MB
ANOMALOUS TROUGH AT 3 TO 4 SIGMA IS PROGGED TO SLIDE SOUTH ALONG THE
WESTERN CONUS LATE IN THE WEEK. THIS WILL AID IN AMPLIFICATION OF A
DOWNSTREAM RIDGE OVER THE CENTRAL ROCKIES/PLAINS STATES LATE
THUR...THEN STEADILY PUSH EAST FRI ACROSS THE GREAT LAKES
REGION/OHIO VALLEY.
BEYOND FRI AND INTO THE UPCOMING WEEKEND...ENSEMBLE MEMBERS BEGIN TO
DIVERGE SUGGESTING A REDUCTION IN THE CONFIDENCE IN THIS TIME FRAME.
THE MAJORITY OF ENSEMBLE MEMBERS SUGGEST THAT DRY AIR WILL LINGER
THROUGH SAT FOR THE REGION WITH THE WEAKENING INFLUENCE OF THE LLVL
RIDGE. THEN THE AFOREMENTIONED POTENT TROUGH PUSHES INTO THE
FOUR-CORNERS REGION OF THE CONUS. THIS PATTERN WOULD SUGGEST THAT
RETURN FLOW MOISTURE SHOULD KICK-IN LATE IN THE WEEKEND...WITH
DECENT ENERGY ROUNDING THE TROUGH AXIS INTO THE SOUTHERN PLAINS. IF
THIS SCENARIO VERIFIES THE END OF THE WEEKEND COULD BE A STEADY
RAMP-UP TOWARDS MILD/CONVECTIVE WEATHER.
DESPITE ANOMALOUSLY COOL TEMPERATURES THUR IN THE 40S...THE 850MB
THERMAL TROUGH QUICKLY DEPARTS WITH A STEADY WARMING TREND THROUGH
THE WEEKEND. AFTN TEMPS BY SAT/SUN COULD EASILY BE BACK INTO THE 50S
POSSIBLY LOW 60S SUN.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* POSSIBLE BRIEF SHOWERS THIS AFTERNOON. MORE WIDESPREAD ACTIVITY
MOVING IN OVERNIGHT.
* IFR VSBYS NOTED IN PIA/BMI/PNT AREA...NOT EXPECTED TO SLIDE
NORTHEAST ALONG THE FRONT...BUT WORTH WATCHING.
* LIGHT AND VARIABLE WINDS BECOMING NORTHEASTERLY THIS EVENING.
* LOWERING CIGS/VSBYS OVERNIGHT...EVENTUALLY DROPPING TO IFR OR
LOWER TOMORROW.
LENNING
//DISCUSSION...UPDATED 18Z...
PASSAGE OF A WEAK FRONT THIS MORNING BROUGHT THINNING OR AT LEAST
HIGHER CIGS FOR ALL BUT THE GYY AREA. VERY WEAK PRESSURE GRADIENT
IN VICINITY OF THIS FEATURE HAS ALLOWED WINDS TO GO CALM OR LIGHT
AND VARIABLE ACROSS A WIDE AREA. A LOW PRESSURE CENTER LIFTING OUT
OF THE SOUTHERN PLAINS WILL GRADUALLY INCREASE WINDS STARTING THIS
EVENING...BUT THE CONTINUED PROXIMITY OF THE FRONT WILL PROVIDE
UNCERTAINTIES IN WIND DIRECTIONS. BEST ESTIMATE IS FOR NORTHEAST
FLOW TO DEVELOP OVERNIGHT...WITH WINDS VERY GRADUALLY VEERING TO
EAST AND THEN SOUTHEAST AS THE STALLED OUT FRONT AHEAD OF THE LOW
STARTS TO MOVE BACK NORTH AGAIN. FORECAST MODELS SHOW THE LOW
CENTER CROSSING NORTHWEST ILLINOIS TOMORROW NIGHT...WITH ALL BUT
RFD IN THE WARM SECTOR WITH SOUTHERLY FLOW AFTER MIDNIGHT TUESDAY
NIGHT.
CONDITIONS DETERIORATE OVERNIGHT WITH ONSET OF PRECIPITATION. BY
TOMORROW AFTERNOON EXPECTING A PROLONGED PERIOD WITH IFR OR
POCKETS OF LIFR ACROSS MOST OF THE AREA WITH PERSISTENT RAIN.
VSBYS MAY BE A PROBLEM FROM TIME TO TIME...BUT CIGS APPEAR TO BE
THE PRIMARY CONCERN BASED ON UPSTREAM TRENDS. LIKELY WILL HAVE TO
MAKE MANY CHANGES TO SPECIFIC ELEMENTS AS THE TIME DRAWS
CLOSER...BUT GENERAL TRENDS ARE REFLECTED IN TAFS.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM TO HIGH CONFIDENCE THAT ANY SHOWERS TODAY WOULD BE BRIEF
AND WOULD NOT DROP CIGS/VSBYS BELOW VFR.
* MEDIUM CONFIDENCE IN WIND TRENDS TONIGHT.
* HIGH CONFIDENCE OF PROLONGED IFR OR LOWER TOMORROW...BUT MEDIUM
TO LOW CONFIDENCE IN TIMING AND SEVERITY.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUE NIGHT...MVFR...PERIODS OF IFR. RA WITH A CHANCE OF TS.
WED...MVFR BECOMING VFR. CHANCE OF SHOWERS.
THU...VFR. WX NIL.
FRI...VFR. WX NIL.
SAT...VFR. WX NIL.
SUN...VFR. CHANCE SHRA.
TRS
&&
.MARINE...
323 AM CST
WINDS HAVE GRADUALLY BEEN TRENDING DOWN THROUGH THE NIGHT AND
EARLY MORNING HOURS...MORE SO OVER THE SOUTHERN HALF OF THE LAKE
WHERE HIGH PRESSURE IS BEGINNING TO ENCROACH FROM THE SOUTH.
ACROSS THE NORTH...BREEZY CONDITIONS ARE STILL BEING OBSERVED BUT
WILL CONTINUE TO TAPER AS THE LOW OVER ONTARIO CONTINUES TO LIFT
AWAY FROM THE REGION. THE NEXT WEATHER SYSTEM OF CONCERN WILL
BEGIN TO TAKE SHAPE OVER THE CENTRAL PLAINS OVERNIGHT
TONIGHT...AND QUICKLY LIFT NORTHEAST REACHING LAKE MICHIGAN LATE
TUESDAY NIGHT. MODELS CONTINUE TO SHOW MODEST DIFFERENCES BETWEEN
THE TRACK AND INTENSITY OF THIS LOW...THUS THE IS A FAIR DEGREE OF
UNCERTAINTY IN TIMING THE WIND SHIFTS AND WIND MAGNITUDES. DOES
APPEAR THAT THE FRONTAL BOUNDARY WILL STALL ACROSS SOUTHERN OR
CENTRAL PORTIONS OF THE LAKE TUESDAY WITH A BAND OF LIGHTER
WINDS...BUT WINDS SHOULD SHARPLY INCREASE TO THE SOUTH OR NORTH OF
THE FRONTAL ZONE. AS THE LOW PASSES NORTHEAST OF THE LAKE
WEDNESDAY...A TRAILING COLD FRONT WILL SWITCH WINDS AROUND TO THE
NORTHWEST...WITH WINDS FURTHER INCREASING...AND LOW END GALES
POSSIBLE. WINDS WILL TREND BACK DOWN THURSDAY AS HIGH PRESSURE
APPROACHES AND MOVES ACROSS THE LAKE ON FRIDAY. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
