304 PM CDT
ANTI-CYCLONIC FLOW REMAINS CENTERED ACROSS THE TENNESSEE VALLEY
INFLUENCING WEATHER ACROSS NORTHERN IL/NORTHWEST THIS AFTERNOON.
PRESSURE GRADIENT HAS STEADILY TIGHTENED ACROSS THE WESTERN GREAT
LAKES...COUPLED WITH FULL SUNSHINE AND SFC WINDS HAVE INCREASED INTO
THE LOW/MID TEENS. AFTN TEMPS HAVE FINALLY WARMED INTO THE 60S
ACROSS CWFA WITH A FEW 70 DEG ACROSS THE SOUTHERN TIER INTO CENTRAL
IL.
QUASI-STATIONARY FRONTAL BOUNDARY WAS DRAPED ACROSS LAKE SUPERIOR
AND EXTENDS WEST THROUGH THE CENTRAL ROCKIES. RETURN FLOW MOISTURE
WILL CREEP NORTHWEST INTO THE SOUTHERN PLAINS AS A 500MB TROUGH AXIS
PIVOTS EAST THROUGH THE ROCKIES. THIS WILL ALLOW A SHORTWAVE TO
DEVELOP ON THE LEE-SIDE OF THE ROCKIES OVERNIGHT. SKIES WILL REMAIN
MOSTLY CLEAR THROUGH THE OVERNIGHT PERIOD...WITH JUST SOME CIRRUS
BEGINNING TO ADVECT EAST EARLY WED MORNING. WITH DRY SFC CONDS IN
PLACE AND NOT ANTICIPATING WINDS TO FALL OFF SUBSTANTIALLY...TEMPS
SHOULD NOT RADIATE AS EFFICIENTLY AS IN PREVIOUS NIGHTS.
ANTICIPATING
A RATHER MILD NIGHT WITH TEMPS IN THE LOW/MID 40S OR UPPER 40S
CLOSER TO LAKE MICHIGAN.
WEDNESDAY THROUGH THURSDAY...
500MB TROUGH AXIS CONTINUES TO SLOWLY PIVOT EAST ACROSS THE CENTRAL
PLAINS DURING THE DAY WED AS THE SFC SHORTWAVE IS EXPECTED TO REMAIN
RELATIVELY IN PHASE WITH THE UPPER LEVEL SUPPORT. PRIMARILY THIS IS
DUE TO A POTENT DOWNSTREAM RIDGE ACROSS THE MIDDLE ATLANTIC AND AN
ANTI-CYCLONIC FLOW PUSHING INTO THE SOUTHERN ROCKIES. EXPECT THIS TO
SLOWLY BRING THE FRONTAL BOUNDARY SOUTH ACROSS THE CWFA...HOWEVER
SOLUTIONS CONTINUE TO STRUGGLE WITH ARRIVAL OF PRECIP WED. BOUNDARY
LAYER SHOULD REMAIN RELATIVELY DRY THROUGH MUCH OF THE DAY
WED...HOWEVER A STEADY POOLING OF MOISTURE FROM THE NORTHWEST
THROUGHOUT THE AFTERNOON AND EVENING HOURS IS EXPECTED. THE SREF
CONTINUES TO DEMONSTRATE NOISE WITH PRECIP ONSET...SO CONFIDENCE IS
A STRUGGLE. NONETHELESS IT STILL APPEARS PRECIP SHOULD BE OVERHEAD
BY WED EVENING. THE NEXT CHALLENGE WILL BE QPF TOTALS. MODELS DIFFER
ON THE TOTALS...THUS HAVE OPTED TO LEAN HEAVILY TOWARDS SREF QPF
PRECIP FOR THE WED/THUR PERIOD.
SFC ANTI-CYCLONIC FLOW ACROSS THE CENTRAL PLAINS CONTINUES TO ADVECT
EAST FROM THE CENTRAL PLAINS ELONGATING NORTH ACROSS THE WESTERN
GREAT LAKES. THIS MAY ALLOW A SHARP CUTOFF OF PRECIP OVER THE
CWFA...BRINGING AN END TO THE PRECIP BY MIDDAY THUR. ENOUGH DRY AIR
WILL EVENTUALLY FILTER INTO THE REGION AND ALLOW SKY TO BECOME
PARTLY CLOUDY. TEMPS ALOFT DO NOT APPEAR TO BE TOO COOL...HOWEVER
WITH CONSIDERABLE FILTERING OF THE SUN THUR EXPECT HIGHS TO STRUGGLE
TO PUSH BEYOND THE MID/UPR 40S POSSIBLY 50 DEG IN SOME LOCATIONS.
FRIDAY THROUGH MONDAY...
ACTIVE PATTER CONTINUES TO BE ADVERTISED BY ENSEMBLES THROUGH THE
WEEKEND. 500MB WAVE PATTERN HAS A RIDGE PUSHING EAST ACROSS THE
GREAT LAKES REGION FRI/SAT. THIS SHOULD KEEP DRY AIR IN
PLACE THROUGH AT LEAST FRI...WITH JUST SLIGHT CHANCE OF PRECIP FOR
SAT AFTN AS OPERATIONAL MODELS CONTINUE TO ADVERTISE A POTENT
SHORTWAVE DEVELOPING OVER THE SOUTHERN PLAINS AND RAPIDLY
STRENGTHENING AND LIFTING NORTHEAST. THE TREND HAS BEEN FOR A
FURTHER NORTHWEST PATH OF THIS SYSTEM...WHICH MAY END UP PREVENTING
PRECIP FROM ARRIVING SAT AFTN AND PUSHING IT INTO SUN. THIS SCENARIO
IS GROWING IN CONFIDENCE AS THE DOWNSTREAM RIDGE MAY BE SLIGHTLY
STRONGER THAN OPERATIONAL SOLUTIONS ARE ANTICIPATING. TEMPERATURES
THROUGH THE EXTENDED PERIODS ARE EXPECTED TO BE MAINLY IN THE
50S...POSSIBLY REACHING 60 DEG ON SAT. OVERNIGHT LOWS WILL MAINLY BE
IN THE 30S TO A FEW NIGHTS IN THE LOWER 40S.
WITH A LARGE ANOMALOUS TROUGH PUSHING INTO THE WESTERN CONUS...THIS
SETS THE STAGE FOR POTENTIAL CONVECTION EARLY NEXT WEEK. AIDING TO
THE CONFIDENCE OF SUCH A POTENTIAL SCENARIO IS A STRENGTHENING LLVL
JET AS 850MB WINDS FROM THE SOUTH/SOUTHWEST 3 SIGMA ABOVE NORMAL
WITH MINIMAL SPREAD AMONGST ENSEMBLES.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 02Z...
* SOUTHWESTERLY LOW LEVEL JET AROUND 020 AGL INCREASING FROM
30-35KT TO 35-45KT DURING THE LATE EVENING.
* WIND SHIFT WITH FROPA LATER WED AFTERNOON.
* ONSET OF POST-FRONTAL -RA.
TRS
//DISCUSSION...UPDATED 00Z...
SHARP POSITIVE TILTED UPPER TROF FROM NORTHERN MANITOBA TO WESTERN
AZ AT 00Z WITH WATER VAPOR SATELLITE LOOP SHOWING A CLOSED UPPER
LOW FORMING OVER UT. STRONG SW LOWER LEVEL FLOW HAD BEEN GRADUALLY
SHIFTING E AHEAD OF THE UPPER SYSTEM AND HAD REACHED W CENTRAL...
NW AND N CENTRAL IS AS WELL AND SOUTHERN WI EARLY THIS EVE.
MODELS SHOW WINDS AROUND 2K FT AGL 25-35KT INCREASING TO 35-45KT
DURING THIS EVE. WITH CLR SKY AND 15 DEG F DEW POINT DEPRESSIONS
THE SFC WILL CONTINUE TO DECOUPLE AND THE SOUTHWESTERLY LLJ
INCREASE SO HAVE INCLUDED WIND SHEAR IN TAFORS FOR TONIGHT.
THE UPPER TROF AND THE UPPER LOW ARE PROGGED TO MOVE E OUT OVER
THE PLAINS DURING WED. AS THE NORTHERN PORTION OF THE TROF MOVES
TO OVER CENTRAL ONTARIO...LAKE SUPERIOR AND THE UPPER MS VALLEY BY
00Z THU THE FRONT CURRENTLY LOCATED ACROSS NW WI...SE MN...NE AND
SW IA WILL HAVE VERY GRADUALLY SHIFTED E TO FAR NE IL AND W
CENTRAL IL. WHILE WINDS MAY BE A BIT GUSTY /G15-20KT/ AFTER SOME
SURFACE HEATING WED MORNING AS MIDDAY APPROACHES THE LESSER
PRESSURE GRADIENT AHEAD OF THE SLOWLY APPROACHING COLD FRONT WILL
SHIFT E OVER THE LOCAL TERMINALS. CFP EXPECTED AROUND 19Z WED AT
RFD AND 22Z WED AT ORD...MDW...DPA.
THE STRONG BAROCLINIC ZONE WILL REMAIN BEHIND THE FRONT AND MID
LEVEL ISENTROPIC UPGLIDE ARRIVES OVER N CENTRAL IL LATE MORNING-
MIDDAY WED...AND NE IL EARLY-MID WED EVE.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* HIGH CONFIDENCE IN WIND FCST TONIGHT INTO WED.
* HIGH CONFIDENCE IN WIND SHEAR FORECAST TONIGHT.
* HIGH CONFIDENCE NO SIG CLOUDS TONIGHT INTO WED AFTERNOON.
* MODERATE CONFIDENCE CIGS AND VSBYS REMAIN VFR LATE WED
AFTERNOON AND EVE.
* MODERATE CONFIDENCE IN TIMING OF CFP WED +/- 1-2 HRS.
* MODERATE CONFIDENCE IN TIMING OF ONSET OF -RA WED +/- 1-2 HRS.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THU...MVFR CIGS AND -RA BECOMING VFR BY LATE MORNING.
FRI...VFR. WX NIL.
SAT...VFR. WX NIL.
SUN...VFR. SLGT CHC SHRA.
MON...VFR.
TRS
&&
.MARINE...
207 PM CDT
SOUTHERLY WINDS WILL REMAIN IN THE 20 TO 30 KT RANGE TONIGHT
INTO WEDNESDAY AHEAD OF AN APPROACHING COLD FRONT FROM THE UPPER
MISSISSIPPI VALLEY. THIS COLD FRONT WILL PUSH ACROSS FAR NORTHERN
LAKE MICHIGAN BY EARLY WEDNESDAY MORNING. THE COLD FRONT SHOULD
CLEAR THE ENTIRE LAKE BY WEDNESDAY EVENING. NORTH TO NORTHEASTERLY
WINDS WILL BE THE MAIN STORY BEHIND THIS FRONT AS THEY INCREASE
WEDNESDAY NIGHT. A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM
THE PLAINS NORTHWARD ACROSS THE UPPER MIDWEST WILL BUILD IN ACROSS
THE NORTHERN PORTIONS OF THE LAKE WEDNESDAY NIGHT AND THURSDAY. AT
THE SAME TIME...A POTENT AREA OF LOW PRESSURE WILL MOVE ACROSS THE
MID MISSISSIPPI VALLEY EARLY THURSDAY. THE PRESSURE GRADIENT
ASSOCIATED WITH THESE TWO PRESSURE SYSTEMS APPEARS TO PRODUCE THE
STRONGEST WINDS...NEAR GALE FORCE...ACROSS THE SOUTHERN HALF OF THE
LAKE WEDNESDAY NIGHT INTO THURSDAY. THE SURFACE HIGH WILL FINALLY
BUILD ACROSS THE LAKE THURSDAY NIGHT INTO FRIDAY...PRODUCING A PERIOD
OF LIGHTER WINDS. HOWEVER...WINDS LOOK TO INCREASE OUT OF THE SOUTH
FRIDAY NIGHT INTO THE WEEKEND AS ANOTHER STRONG STORM SYSTEM
DEVELOPS ACROSS THE CENTRAL ROCKIES AND LIFTS NORTH NORTHEAST WARD
ACROSS THE UPPER MISSISSIPPI VALLEY BY THE END OF THE WEEKEND.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
