340 AM CDT
WEAKENING SURFACE LOW PRESSURE WAS LIFTING NORTH ACROSS NORTHEAST
WISCONSIN EARLY THIS MORNING...WITH TRAILING OCCLUDED COLD FRONT
ABOUT TO PUSH EAST OF THE CWA. LINGERING LIGHT SHOWERS WITH FRONT
SHOULD EXIT BY 12Z. PATCHY FOG HAS DEVELOPED IN SOME SPOTS WHERE
SKIES HAVE CLEARED OVER MOIST GROUND...HOWEVER CLOUDS MOVING BACK
INTO WESTERN ILLINOIS WILL LIKELY KEEP FOG FROM BECOMING TOO
WIDESPREAD THIS MORNING. SUBSIDENCE WILL INCREASE LATER THIS MORNING
AS UPPER TROUGH MOVES OFF...AND RIDGING BUILDS IN TO THE AREA THIS
AFTERNOON. THIS SHOULD ALLOW DECREASING CLOUD COVER BY THIS
AFTERNOON.
SOUTHERLY FLOW DEVELOPS LATER TONIGHT AFTER WEAK SURFACE HIGH
PRESSURE RIDGE PASSES ACROSS THE FORECAST AREA LATE THIS
AFTERNOON/EARLY THIS EVENING. WARM ADVECTION DEVELOPS IN EARNEST BY
EARLY TUESDAY...AHEAD OF POSITIVE TILT UPPER TROUGH DEVELOPING
ACROSS THE NORTHERN CONUS. DRY AIR AND LOW LEVEL THERMAL RIDGE
SHOULD HELP TO PUSH TEMPS INTO THE LOWER AND MIDDLE 60S
TUESDAY...MORE ALONG THE LINES OF THE WARMER MET GUIDANCE.
UPPER TROUGH DIGS ACROSS THE CENTRAL CONUS TUESDAY NIGHT AND
WEDNESDAY. NORTHERN STREAM SHORT WAVE PASSING NORTH OF THE GREAT
LAKES TRAILS A SLOW MOVING COLD FRONT ACROSS WISCONSIN AND EASTERN
IOWA TUESDAY NIGHT...AND ACROSS LAKE MICHIGAN AND ILLINOIS ON
WEDNESDAY. GUIDANCE IS IN GOOD AGREEMENT IN DEVELOPING PRECIP ON THE
COOL SIDE OF THE BAROCLINIC BOUNDARY...THOUGH VARIOUS MODELS ARE A
LITTLE DIFFERENT IN HOW FAR THE FRONT PUSHES INTO THE WFO LOT CWA.
THE GREATER CHANCE OF PRECIPITATION WILL BE ACROSS THE NORTHWEST
PART OF THE FORECAST AREA WEDNESDAY...AND HAVE BASED POPS MORE ALONG
SLOWER ECMWF/WRF SOLUTIONS AT THIS POINT.
SHORT WAVE MOVING INTO THE SOUTHERN PART OF THE TROUGH IS PROGGED
TO DEVELOP A CLOSED UPPER LOW ACROSS KANSAS AND MISSOURI WEDNESDAY
NIGHT...WITH RAIN SPREADING ACROSS THE REMAINDER OF THE CWA AS
BAROCLINIC ZONE NORTH OF SURFACE FRONT BECOMES FOCUS FOR DEVELOPING
DEFORMATION ZONE INTO THURSDAY. SURFACE LOW QUICKLY OCCLUDES AND
MOVES INTO THE LOWER OHIO VALLEY THURSDAY NIGHT...WITH PRECIP
DIMINISHING FROM NORTHWEST TO SOUTHEAST ACROSS THE CWA.
HIGH PRESSURE THEN SPREADS ACROSS THE GREAT LAKES REGION FRIDAY AS
UPPER RIDGE DEVELOPS ALOFT...AND DEEP TROUGH TAKES SHAPE OVER THE
WESTERN CONUS IN A CONTINUATION OF HIGH AMPLIFIED UPPER AIR PATTERN.
GFS/ECMWF IN PRETTY GOOD AGREEMENT IN A NEGATIVE TILT SHORT WAVE AND
ASSOCIATED DEEP SURFACE LOW LIFTING NORTHEAST ACROSS THE PLAINS AND
INTO WESTERN MINNESOTA ON SATURDAY. THIS IS EXPECTED TO RESULT IN
GUSTY SOUTH WINDS...WITH ANOTHER SHOT OF STRONG WARM ADVECTION. HAVE
BUMPED MAX TEMPS A BIT FOR SATURDAY...IN LINE WITH 00Z MEX GUIDANCE
WHICH IS AT THE HIGH END OF THE ENSEMBLE ENVELOPE. MAY EVENTUALLY
NEED TO RAISE TEMPS MORE...AS LOCATION OF THERMAL RIDGE AND DIURNAL
TIMING COME INTO BETTER FOCUS. OCCLUDED COLD FRONT PUSHES THROUGH
THE FORECAST AREA SATURDAY NIGHT AND SUNDAY...WITH RELATIVELY LOW
CHANCE ATTENDANT POPS. NO REAL PUSH OF REALLY COLD AIR SEEN AT THIS
DISTANCE INTO EARLY NEXT WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* VFR-LEVEL CEILINGS DEVELOPING BY MID AFTERNOON.
PAW
//DISCUSSION...UPDATED 18Z...
SOUTHWEST FLOW PERSISTING AT LOW LEVELS THROUGH TUESDAY. A WEAK
UPPER LEVEL DISTURBANCE MOVING ACROSS THE AREA WILL HELP TO
PRODUCE SOME MVFR/VFR CEILINGS ACROSS NORTHERN IL AND NORTHWEST
DURING THE AFTERNOON HOURS. TONIGHT WE SHOULD HAVE A BIT MORE WIND
THAN LAST NIGHT...SO NOT EXPECTING A REPEAT OF THE FOG TUESDAY
MORNING.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH PCONFIDENCE IN ALL FORECAST ELEMENTS.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...VFR.
WEDNESDAY...CHANCE OF SHRA LATE...OTHERWISE VFR.
THURSDAY...CHANCE OF SHRA...OTHERWISE VFR.
FRIDAY...VFR.
SATURDAY...CHANCE OF SHRA...OTHERWISE VFR.
SUNDAY...VFR.
RODRIGUEZ
&&
.MARINE...
221 PM CDT
SOUTHERLY WINDS WILL BE ON THE INCREASE TONIGHT INTO TUESDAY AS AN
AREA OF LOW PRESSURE MOVES ACROSS SOUTHERN CANADA. THIS LOW WILL
PUSH A COLD FRONT FROM THE NORTHERN PLAINS ACROSS THE UPPER
MISSISSIPPI VALLEY BY TUESDAY. THIS COLD FRONT WILL CONTINUE
EASTWARD ACROSS LAKE MICHIGAN LATE WEDNESDAY AND WEDNESDAY NIGHT. AT
THE SAME TIME...AN AREA OF LOW PRESSURE IS FORECAST TO DEVELOP ALONG
THIS FRONT ACROSS THE SOUTHERN PLAINS. THIS LOW WILL THEN TRACK
EASTWARD ACROSS MISSOURI AND ILLINOIS WEDNESDAY NIGHT AND THURSDAY.
IT APPEARS THAT THE COMBINATION OF THE COLD AIR MOVING OVER THE LAKE
BEHIND THE FRONT...COMBINED WITH A STRENGTHENING PRESSURE GRADIENT
ASSOCIATED WITH THE DEVELOPING SURFACE LOW...WILL PRODUCE A
PERIOD OF STRONG NORTH TO NORTHEASTERLY WINDS ACROSS LAKE MICHIGAN
WEDNESDAY INTO THURSDAY. SOME GALE FORCE WINDS ARE POSSIBLE DURING
THIS PERIOD...ESPECIALLY OVER THE SOUTH HALF OF THE LAKE.
HOWEVER...DUE TO ABOVE AVERAGE UNCERTAINTY ON THE EXACT TIMING AND
TRACK OF THE SURFACE LOW...I AM NOT CONFIDENT ENOUGH TO INCLUDE
WINDS OF THIS MAGNITUDE AT THIS TIME.
FOLLOWING THIS STORM...A SURFACE HIGH WILL BUILD IN ACROSS THE GREAT
LAKES ON THURSDAY NIGHT AND FRIDAY. THIS WILL PRODUCE A PERIOD OF
LIGHTER WINDS BEFORE SOUTHERLY WINDS INCREASE AGAIN INTO NEXT
WEEKEND AHEAD OF A POTENT STORM SYSTEM EXPECTED DEVELOP ACROSS THE
CENTRAL ROCKIES BEFORE LIFTING NORTH NORTHEAST WARD ACROSS THE UPPER
MISSISSIPPI VALLEY.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
