327 AM CDT
THE MOTS /MORE OF THE SAME/ PHILOSOPHY WILL SLOWLY BE COMING TO AN
END THIS WEEK AS FALL MAKES A TRIUMPHANT RETURN...BRINGING CHILLY
AND WET WEATHER WITH IT. LEADING UP TO THE MIDDLE OF THE
WEEK...THE REGION WILL STILL BE ABLE TO ENJOY THE UNSEASONABLY
WARM AND CLIMATOLOGICALLY DRY CONDITIONS.
LARGE RIDGE OVER THE EASTERN OHIO VALLEY IS SLOWLY WEAKENING BUT
CONTINUING TO DOMINATE OUR WEATHER FOR THE NEAR TERM AND THE
SUNDAY WEATHER PICTURE WILL AGAIN BE PRIMARILY UNCHANGED.
SHORTWAVE DIGGING THROUGH WESTERN TEXAS WILL BEGIN ROTATE AROUND
THE BASE OF AN UPPER LEVEL TROUGH THAT SPANS MUCH OF THE
ROCKIES...AND EVENTUALLY LIFT NORTH THROUGH THE PLAINS...SPAWNING
ANOTHER WEAK SURFACE LOW THAT WILL MOVE IN A SIMILAR MOTION TO THE
DECAYING LOW ACROSS WESTERN NEBRASKA THIS MORNING. PRESSURE
GRADIENT WILL ORIENT THIS AFTERNOON TO ALLOW SOUTHERLY WINDS TO
TURN A LITTLE MORE SOUTHEASTERLY...IMPACTING TEMPERATURES ACROSS
COASTAL LOCATIONS. STILL FEEL THAT THE LAKEFRONT CHICAGO METRO
WILL REACH THE MID TO UPPER 70S BEFORE THE SOUTHEAST INFLUENCE
INCREASES. THE SAME TREND WILL BE NOTED NORTH ACROSS LAKE COUNTY
AS WELL. OTHERWISE WITH MID LEVELS ONLY COOLING SLIGHTLY...LOWER TO
MID 80S ACROSS THE REGION WILL BE EXPECTED AGAIN. FORECAST
SOUNDINGS INDICATE EFFICIENT MIXING UP TO OR SLIGHTLY ABOVE 900
HPA THIS AFTERNOON...AND WE SHOULD SEE THE DRY AIR ALOFT...TRANSLATE
DOWN TO THE SURFACE AGAIN. SIMILAR TO THE PREVIOUS FEW DAYS...DEWPOINTS
WILL FALL INTO THE AFTERNOON HOURS INTO THE UPPER 40S WITH
HUMIDITIES HAVING A SIMILAR RESPONSE INTO THE 30 PCT RANGE FOR
AREAS GENERALLY SOUTH OF I-80.
THE RIDGE WILL BEGIN TO BREAK DOWN EARLY IN THE WORK WEEK...BRINGING
AN END TO THE UNSEASONABLY WARM AND DRY WEATHER. MODELS ARE STILL IN
PRETTY GOOD AGREEMENT THE OVERALL EVOLUTION AND TIMING OF A COLD
FRONT SWINGING THROUGH THE AREA ON WEDNESDAY. BEGAN TO INTRODUCE THE
MENTION OF SHOWERS OVERNIGHT TUESDAY FOR AREAS WEST OF I-39...WITH
THE ENTIRE CWA BEING UNDER THE GUN BY WEDNESDAY. CONVERGENCE ALONG
THE FRONT IS MARGINAL AND INSTABILITY IS RATHER ANEMIC...AND THE BEST
DYNAMICS REMAINING ACROSS SOUTHERN ILLINOIS. FORECAST SOUNDINGS ARE
SHOWING SLIGHT ELEVATED INSTABILITY INTO THE OVERNIGHT HOURS OF
WEDNESDAY WITH MID LEVEL LAPSE RATES APPROACHING 7.5 DEG/C AS A
WEAK S/WV ROTATES THROUGH...AND WILL MAINTAIN THE MENTION OF
ISOLATED THUNDER THROUGH THAT TIME...THOUGH IT WILL LIKELY BE RAIN
WITH A FEW RUMBLES.
BEHIND THE FRONT WILL BRING THE RETURN TO FALL-LIKE WEATHER WITH
TEMPERATURES DWINDLING THROUGH THE WEEK. CONFIDENCE THEN FALLS ON
HOW LONG THE SHOWERS WILL LINGER AS AN UPPER LOW MIGRATES
OVERHEAD...THROUGH THE END OF THE WEEK. EXTENDED CONSENSUS IS STILL
HIGHLIGHTING OFF AN ON CHANCES FOR LIGHT RAIN THROUGH FRIDAY AND
AGREE THAT IT IS REASONABLE. WHILE TEMPERATURES WILL STRUGGLE TO
REACH 60 BY FRIDAY...THERE ARE INDICATIONS THAT WE COULD SEE A
LAST GASP OF SUMMER BY SUNDAY OR MONDAY /WITH HIGHS POPPING 5 TO
10 DEGREES ABOVE NORMAL/...BEFORE ANOTHER FRONT PLOWS THROUGH.
OBVIOUSLY...LONG RANGE FORECASTS FOR LATE NEXT WEEK NEED TO BE
TAKEN WITH A GRAIN OF SALT THOUGH THE TREND IS ENCOURAGING AFTER
THIS RETURN TO FALL.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 15Z...
* LIGHT AND VARIABLE WINDS TURNING SOUTHEAST THEN EAST FROM LATE
MORNING THROUGH AFTERNOON. SPEEDS UNDER 10 KT EXPECTED.
JEE
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE CONTINUES TO BE SPRAWLED ACROSS THE EASTERN U.S.
THIS MORNING WITH A RIDGE AXIS ORIENTED FROM CENTRAL OHIO INTO
NORTHWEST INDIANA AND NORTHERN ILLINOIS. CLEAR SKIES AND LIGHT AND
VARIABLE WINDS THIS MORNING WILL GIVE WAY TO A SOUTH TO SOUTHEAST
WIND BY MID MORNING WITH DIRECTIONAL FLUCTUATIONS CONTINUING...
THOUGH SPEEDS WILL PROBABLY REMAIN 6 KT OR LESS. IFR VSBY IN MIST
ACROSS NORTHWEST INDIANA MAY TRY TO SPREAD TOWARD GYY AS THEY ARE
RIGHT UNDER THE RIDGE BUT THINK THAT THIS IS A LOW PROBABILITY
SCENARIO WITH THE SUN NOW COMING UP AND A SEVERAL DEGREE TEMP-
DEWPOINT SPREAD. THE RIDGE AXIS WILL GRADUALLY LIFT NORTHWARD INTO
THIS EVENING BUT IN THE MEANTIME WILL ALLOW WINDS TO TURN MORE
EASTERLY THIS AFTERNOON...ESPECIALLY ACROSS THE CHICAGO METRO AREA
WHERE LAKE MICHIGAN WILL LIKELY HELP THIS ALONG...AND PROVIDE A
LITTLE EXTRA PUSH IN THE WAY OF WIND SPEEDS IN THE 5 TO 10 KT
RANGE BY LATE AFTERNOON. GYY SHOULD SEE MORE OF A NORTHEASTERLY
DIRECTION GIVEN THEIR LOCATION RELATIVE TO THE LAKE. AREAS FURTHER
INLAND INCLUDING DPA AND RFD ARE EXPECTED TO SEE MORE OF AN
EASTERLY DIRECTION BY LATE AFTERNOON AS WELL. WHAT SPEED THERE IS
THIS AFTERNOON WILL DIMINISH TO A FEW KNOTS OR LESS THIS EVENING.
SUNNY SKIES WILL PREVAIL WITH AN INCREASE IN HIGH CIRRUS EXPECTED
THIS EVENING/TONIGHT.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 15Z...
* HIGH CONFIDENCE IN WIND SPEED...BUT MEDIUM CONFIDENCE IN TIMING
OF WIND DIRECTION CHANGES.
JEE
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH TUESDAY...VFR.
WEDNESDAY AND THURSDAY...CHC SHRA/SLGT CHC TSRA BRIEF MVFR...
OTHERWISE VFR.
FRIDAY...SLGT CHC SHRA. OTHERWISE VFR.
SATURDAY...VFR.
MDB
&&
.MARINE...
240 AM CDT
HIGH PRESSURE REMAINS SPRAWLED ACROSS THE EASTERN U.S. EARLY THIS
MORNING. THE HIGH WILL EXPAND FURTHER WESTWARD INTO THE WESTERN
LAKES AND MID/UPPER MISSISSIPPI RIVER VALLEY TODAY. THIS WILL RESULT
IN DIMINISHING WINDS...ESPECIALLY ACROSS THE SOUTH END OF THE LAKE
WHERE LIGHT AND VARIABLE WINDS LOOK TO SET UP THIS AFTERNOON THANKS
TO A RIDGE AXIS DEVELOPING. THE HIGH WILL DRIFT EASTWARD MONDAY INTO
TUESDAY AS LOW PRESSURE LIFTS FROM THE HIGH PLAINS NORTHWARD INTO
FAR WESTERN ONTARIO TUESDAY. SOUTHERLY WINDS WILL INCREASE IN SPEED
SOMEWHAT BY TUESDAY WITH THE PRESSURE GRADIENT TIGHTENING. LOW
PRESSURE WILL THEN TAKE SHAPE ACROSS THE NORTHERN PLAINS AND MOVE
EASTWARD DRAGGING A COLD FRONT ALONG WITH IT. STILL NOT CLEAR WHERE
EXACTLY THE LOW WILL PASS RELATIVE TO THE LAKE BUT THE LOW PASSAGE
LOOKS TO OCCUR THURSDAY. COLD AIR WILL THEN MOVE IN BEHIND THE LOW
SETTING UP AN UNSTABLE ATMOSPHERE OVER THE LAKE WHICH WILL COMBINE
WITH THE TIGHT PRESSURE GRADIENT BEHIND THE DEEPENING LOW. WINDS
WILL INCREASE IN SPEED THURSDAY NIGHT AND SHIFT TO A WEST/NORTHWEST
DIRECTION. STILL NEED TO WORK OUT THE DETAILS BUT 20-30 KT WINDS
STILL LOOK PLAUSIBLE AND THERE IS SOME CONCERN THAT LOW END GALES
COULD DEVELOP AS WELL.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
