341 AM CST
IR IMAGERY EARLY THIS MORNING SHOWS A NARROW CHANNEL OF CLEAR SKIES
THAT STRETCHES FROM MISSOURI NORTHEAST THROUGH NORTHERN ILLINOIS
INTO EASTERN WISCONSIN. TEMPERATURES HAVE BEEN ABLE TO RADIATE INTO
THE LOWER TO MIDDLE 30S THIS MORNING...AND IN SOME LOCATIONS ACROSS
FAR NORTHWEST ILLINOIS TEMPS WILL BE IN THE UPPER 20S TO START THE
DAY. WRAP AROUND MOISTURE WAS BEGINNING TO SLIDE SOUTHEAST AS
WELL...CURRENTLY LOCATED OVER EASTERN IOWA STRETCHING NORTHEAST
THROUGH WESTERN WISCONSIN. BASED ON THE CURRENT PATH AND LATEST
TRENDS OF THIS LINE...EXPECT CLOUDS TO PUSH OVER THE CENTRAL
PORTIONS OF THE CWFA AROUND DAYBREAK. THEN THIS LINE SHOULD CONTINUE
TO PUSH EAST.
ONCE CLOUDS ARRIVE THIS MORNING...CHANCES OF SEEING A WARM-UP A VERY
MINIMAL. THE COMBINATION OF STRONG COLD AIR ADVECTION...CONSIDERABLE
SOLAR FILTERING...AND AN 850MB THERMAL TROUGH OF -6 TO -9 DEG C
OVERHEAD SHOULD RESULT IN TEMPS REMAINING IN THE UPPER 30S FOR MANY
LOCATIONS. THE EXCEPTION WOULD BE LOCATIONS CLOSER TO CENTRAL
ILLINOIS...WHICH MAY ONLY SEE PARTLY CLOUDY SKIES TODAY.
THE OTHER CONCERN FOR TODAY WILL BE THE UNSTABLE NATURE OF THE
ATMOSPHERE...AND THE MID-LVL TROUGH AXIS. DEEP MOISTURE REMAINS
TODAY WITH SOME LIFT EXPECTED. DEW PT WILL REMAIN
SUB-FREEZING...THUS EXPECT ANY PRECIP THIS MORNING TO OCCUR WOULD
REMAIN IN A DENDRITIC FORM. BY MIDDAY WITH SOME HEATING ALOFT COULD
AID IN ENHANCING THE PRECIP...WITH DEEP MOISTURE LINGERING AROUND.
THERMAL PROFILES SUGGEST A SHARP DECLINE. THUS NOT ANTICIPATING ANY
ICE PELLETS OR GRAUPEL...ALTHOUGH THE THREAT OF THIS IS NOT ZERO.
CONFIDENCE IS VERY LOW...THUS GOING TO RIDE WITH A RASN MIX. EVEN
THIS COULD END UP BEING ALL SN. NOT ANTICIPATING ANY ACCUMS TODAY
EITHER...WITH POSSIBLY JUST TRACE AMOUNTS.
WITH HEIGHTS BEGINNING TO BUILD IN FROM THE SOUTHWEST AND DEEP
MOISTURE BEGINNING TO PEEL TO THE EAST...ALONG WITH DECOUPLED
WINDS...AND SFC TEMPS WILL STEADILY RADIATE INTO THE 20S. EXPECT
OVERNIGHT LOWS TO END UP FALLING INTO THE MID 20S ACROSS MOST OF THE
CWFA. THE EXCEPTION WILL BE CLOSER TO THE MARINE ENVIRONMENT...WHERE
TEMPS MAY HOLD IN THE UPPER 20S TO LOWER 30S. THERMAL DIFFERENTIAL
WILL REMAIN OVER THE LAKE...THUS LAKE EFFECT CLOUDS AND PRECIP WILL
PERSIST.
FRIDAY...
500MB TROUGH AXIS CONTINUES TO PIVOT EAST AWAY FROM THE GREAT LAKES
REGION...AS THE THERMAL TROUGH AT 850MB BEGINS TO WARM AS WELL. THIS
SHOULD BRING A GRADUAL END TO THE LAKE EFFECT
CLOUDS/PRECIP...HOWEVER IT MAY TAKE UNTIL SAT FOR THIS TO OCCUR.
MEANWHILE THE LARGER STORY WILL BE THE POTENT SYSTEM POISED TO MOVE
ONSHORE NEAR SOUTHERN CALIFORNIA LATE IN THE WEEK. ENSEMBLES HAVE
CONTINUED TO SLOW THIS ARRIVAL...HOWEVER THE POTENCY REMAINS THE
SAME AT -3 TO -4 SIGMA AT 500MB. ANTI-CYCLONIC FLOW WILL BE PRESSING
EAST INTO THE GULF STATES...INFLUENCING THE WEATHER AS FAR NORTH AS
THE GREAT LAKES REGION. THIS SHOULD PROVIDE ENOUGH SUBSIDENCE TO
ERODE MOST CLOUDS DURING THE DAY ACROSS THE CWFA WITH TEMPS
REBOUNDING INTO THE UPPER 40S TO LOWER 50S. IT IS POSSIBLE WITH
WINDS SHIFTING TO THE SOUTHWEST ENOUGH WARM AIR ADVECTION COULD
OCCUR THAT TEMPS COULD BE A FEW DEGREES WARMER YET. AT THIS TIME
HAVE ADJUSTED TEMPS WARMER A DEGREE OR TWO. HAVE ALSO MAINTAINED A
DRY FORECAST...WITH THE EXCEPTION BEING OVER LAKE MICHIGAN DURING
THE DAY.
OVERNIGHT SKIES WILL SEE MINIMAL CLOUD COVER...AND WINDS SHOULD
DECOUPLE. THIS WILL ALLOW TEMPS TO RADIATE EFFICIENTLY INTO THE
30S.
SATURDAY THROUGH WEDNESDAY...
ANOMALOUSLY STRONG 500MB TROUGH CONTINUES TO SLIDE EAST INTO THE
SOUTHWEST CONUS REGION EARLY IN THE WEEKEND. DOWNSTREAM OF THIS
FEATURE ENSEMBLES CONTINUE TO DEMONSTRATE A STEADY INCREASE IN
CONFIDENCE IN A MID-LVL TROUGH SLIDING SOUTHEAST FROM THE CANADIAN
ROCKIES INTO THE CENTRAL PLAINS MON. MEANWHILE ENSEMBLE MEMBERS HAVE
ALSO DEMONSTRATING OVER THE PAST FEW CYCLES OF INCREASING THE
STRENGTH OF THE RIDGE OVER THE FAR SOUTHEAST CONUS.
OPERATIONAL SOLUTIONS CONTINUE TO HINT THAT A SHORTWAVE WILL BE
PUSHING EAST THROUGH THE CENTRAL PLAINS EARLY SUN AND ARRIVING
ACROSS THE WESTERN GREAT LAKES REGION LATE SUN EARLY MON. WHILE THE
PRECISE ARRIVAL TIME WILL CONTINUE TO FLUCTUATE...THE PATTERN PRIOR
TO THIS ARRIVAL IS FOR MUCH OF THE OHIO VALLEY WILL SEE WARM AIR
ADVECTION. THE PRESSURE GRADIENT BETWEEN THE DOWNSTREAM RIDGE AND
THE ARRIVING TROUGH STEADILY TIGHTENS SUN...THUS EXPECT IF MINIMAL
CLOUD COVER CAN OCCUR TEMPS WILL EASILY PUSH INTO THE UPPER 50S SUN
AND POSSIBLY LOWER 60S IN SOME LOCATIONS. WITH A TIGHT PRESSURE
GRADIENT SUN...EXPECT VERY BREEZY CONDITIONS.
IT APPEARS ONCE THE FRONT PUSHES THROUGH EARLY IN THE WEEK...TEMPS
WILL COOL. ALTHOUGH WITH A RELATIVELY FLAT 850MB THERMAL TROUGH...IT
DOES NOT APPEAR TEMPS WILL FALL OFF DRAMATICALLY AT THIS TIME. A FEW
ENSEMBLE MEMBERS SUGGEST A REINFORCING SHOT OF COOLER AIR ARRIVES
TOWARDS THE MIDDLE OF THE WEEK...WHICH COULD AID IN FURTHER COOLING
OF THE SENSIBLE WEATHER.
PRECIPITATION CHANCES WILL BE GREATEST IN THE SUN/MON
TIMEFRAME...HOWEVER RELATIVELY LOW CHANCES EXIST THROUGHOUT THE
REMAINDER OF THE EXTENDED. A FEW ENSEMBLE MEMBERS ALSO SUGGEST A
SYSTEM WILL DEVELOP IN THE SOUTHERN PLAINS AND LIFT NORTHEAST INTO
THE TENNESSEE VALLEY LATE TUE. WITH THE EXPECTED PATTERN...AND THE
LOCATION IN WHICH THESE SOLUTIONS ARE PRODUCING THIS SYSTEM...ONE
COULD IMAGINE A FURTHER NORTHWEST TRACK OVER THE GREAT LAKES REGION
TUE NGT/WED.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* STRATOCUMULUS CEILING LOWERING TO HIGH END MVFR DURING THE DAY.
* W WINDS GUST 20-25KT DURING AFTERNOON.
* SCATTERED -SHSN MID MORNING THROUGH MID AFTERNOON.
TRS
//DISCUSSION...UPDATED 06Z...
AN UPPER LEVEL DISTURBANCE OVER MN WILL MOVE SOUTHEAST ACROSS THE
AREA THURSDAY MORNING INTO THURSDAY AFTERNOON. THE LEADING CLOUD
COVER WITH THIS WAVE IS GENERALLY VFR IN THE 3-5KFT RANGE AND
EXPECT IT TO ARRIVE PRIOR TO SUNRISE. EVENTUALLY EXPECT MVFR CIGS
TO MOVE ACROSS THE AREA BY MID/LATE THURSDAY MORNING. HOWEVER...
STILL SOME UNCERTAINTY AS TO HOW LONG THE MVFR CIGS WILL PERSIST
BUT FOR NOW...GIVEN CURRENT OBSERVATIONS WILL CONTINUE WITH MVFR
CIGS THROUGH MUCH OF THE DAY...BUT COULD BE IMPROVEMENT TO LOW VFR
BY MID AFTERNOON. PRECIP POTENTIAL APPEARS RATHER LIMITED IN TIME
AND OPTED TO INCLUDED JUST A VCSH FOR A 3-4 HR TIME PERIOD THOUGH
MAIN PRECIP TYPE APPEARS TO BE LIGHT SNOW.
WEST/SOUTHWEST WINDS HAVE DIMINISHED TO 10 KTS OR SO WITH A FEW
LOCATIONS REPORTING HIGHER GUSTS. AS CLOUDS COME BACK ACROSS THE
AREA OVERNIGHT...EXPECT GUSTS TO BECOME PREVAILING AGAIN IN THE
15-20KT RANGE BY MID MORNING AND THEN 20-25KTS BY LATE MORNING AND
THEN INTO THE AFTERNOON. WINDS SHOULD QUICKLY DIMINISH WITH SUNSET
THURSDAY WITH CLEARING SKIES OVERNIGHT AS THE UPPER WAVE MOVES
SOUTHEAST OF THE AREA. CMS
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* HIGH CONFIDENCE SKC TIL PREDAWN BCMG BKN-OVC STRATOCU.
* HIGH CONFIDENCE W WIND GUST 20-25KT MIDDAY AND AFTERNOON.
* MEDIUM CONFIDENCE CIGS LOWER INTO MVFR MID-LATE MORNING.
* MEDIUM CONFIDENCE -SHSN OCCURRING.
* MEDIUM CONFIDENCE ANY -SHSN WILL NOT BE OPERATIONALLY
SIGNIFICANT.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...BREEZY. SOUTHWEST WINDS GUSTING 20+ KTS. VFR.
SATURDAY...VFR.
SUNDAY...WINDY. SOUTHWEST WINDS GUSTING 30+ KTS. VFR.
MONDAY...CHANCE OF RAIN. MVFR POSSIBLE.
TUESDAY...SLIGHT CHANCE OF RAIN. CMS
&&
.MARINE...
245 AM CST
THE AREA OF LOW PRESSURE THAT BROUGHT STRONG GALES TO LAKE MICHIGAN
HAS LIFTED NORTH INTO QUEBEC...WITH THE STRONGEST PRESSURE RISES
IN THE WAKE OF THE LOW BEGINNING TO ALSO PUSH NORTH OF THE AREA.
THE PRESSURE GRADIENT IS EXPECTED TO GRADUALLY LET UP FROM THE
SOUTH ALLOWING WINDS TO FURTHER SUBSIDE. EARLY THIS MORNING...A
COUPLE SITES CONTINUE TO REPORT LOW END GALE FORCE
WINDS...INCLUDING THE NORTH BUOY...BUT WINDS WILL TREND DOWN...AND
SOUTH HALF OF THE LAKE HAS ALREADY DROPPED BELOW GALES PER
OBSERVATIONS. WILL ALLOW GALE WARNING FOR SOUTH HALF AND
INDIANA/ILLINOIS NEARSHORE ZONES TO EXPIRE WITH MORNING FORECAST
ISSUANCE...AND WILL HOIST A SMALL CRAFT ADVISORY IN ITS PLACE.
THROUGH THE REMAINDER OF THE WEEK AND INTO THE WEEKEND...AN ACTIVE
WEATHER PATTERN WILL CONTINUE AS A SERIES OF LOW PRESSURE SYSTEMS
TRAVERSE THE NORTHERN PLAINS AND CANADA. THIS WILL KEEP WINDS BRISK
THROUGH MUCH OF THIS PERIOD...WITH GALES POSSIBLE AGAIN SUNDAY AND
SUNDAY NIGHT AS A STRONG LOW PRESSURE SYSTEM MOVES ALONG THE
CANADIAN/US BORDER BEFORE LIFTING NORTHEAST TOWARDS HUDSON BAY. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ868 UNTIL 9 AM THURSDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 AM FRIDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 PM THURSDAY.
&&
$$
