756 PM CDT
FORECAST GRIDS AND DERIVED TEXT PRODUCTS UPDATED FOR CURRENT
TRENDS THIS EVENING WITH LITTLE IF ANY CHANGES MADE FOR
OVERNIGHT.
AN UPPER LOW IS OVER CENTRAL WI EARLY THIS EVENING WITH A PAIR OF
COMPACT BUT POTENT SHORT WAVES ROTATING AROUND THE S END OF THE
UPPER TROUGH THAT EXTENDS SW TO MO.
FIRST IMPULSE MOVES ACROSS NORTHERN IL DURING THE AFTERNOON AND
EARLY EVENING AND IS CURRENTLY OVER THE W SHORE OF LAKE MI JUST E
OF THE WI STATE LINE. THE ASSOCIATED AREA OF RAIN HAS SHIFTED OUT
OVER LAKE MI AND ACROSS NW IN FOR THE MOST PART. SOME SMALL
SHOWERS LINGERING OVER SOUTHERN WI AND NORTHERN IL THOUGH BASED ON
00Z KDVN RAOB THE STRONG ADVECTION OF MID LEVEL DRY AIR SHOULD
PREVENT ANY FURTHER DEVELOPMENT.
THE SECOND IMPULSE WAS APPROACHING THE BASE OF THE UPPER TROUGH AS
IS STARTED TURNING FROM MOVING SSE TO MORE SOUTHWESTERLY WHILE
DROPPING ACROSS EASTERN KS AND WESTERN MO. VORTICITY MAX
ASSOCIATED WITH THIS SECOND SHORT WAVE IS PROGGED TO MOVE E
THROUGH THE BASE OF THE UPPER TROUGH MID TO LATE EVENING AND THEN
START LIFTING NE TO CENTRAL IL BY 06Z AND TO W CENTRAL OR NE IN
BY 12Z MON.
SHOWER ACTIVITY...BOTH IN COVERAGE AND INTENSITY...HAVE BEEN
INCREASING OVER CENTRAL IL PER RADAR LOOP. AS THE VORT MAX EJECTS
OUT LATER THIS EVENING AND OVERNIGHT EXPECT THESE SHOWERS TO MOVE
OVER S AND E PORTIONS OF THE FORECAST AREA BEFORE STRONG MID LEVEL
DRYING SHIFTS ANY SIGNIFICANT THREAT OF ADDITIONAL SHOWERS DURING
THE OVERNIGHT HOURS WILL BE E OF THE FORECAST AREA.
TRS
//PREV DISCUSSION...
256 PM CDT
ABUNDANT MID/HIGH LVL CLOUDS CONTINUE TO BLANKET THE WESTERN GREAT
LAKES THIS AFTERNOON. PRECIPITATION HAS REMAINED LIGHT AND SCATTERED
ACROSS NORTHERN IL...EVENTUALLY WORKING INTO NORTHWEST IN LATER THIS
AFTERNOON AND EVENING. PRESSURE GRADIENT REMAINS TIGHT AS WELL WITH
OCCASIONAL GUSTS BETWEEN 20 AND 30 MPH...HOWEVER ACROSS EASTERN IOWA
THE GRADIENT WAS BEGINNING TO WEAKEN. THUS EXPECT THE WINDS TO
DECOUPLE LATER THIS EVENING. DRY AIR WAS ALSO BEGINNING TO PUSH
ACROSS THE IA/IL STATE LINE AS THE MID-LVL TROUGH AXIS ARRIVES.
FRONTAL PASSAGE CONTINUES TO BE PROGGED FOR THIS EVENING AND WILL
ALLOW SOUTHWEST WINDS TO BECOME WESTERLY THROUGH THE OVERNIGHT
PERIOD. TROUGH AXIS WILL QUICKLY PUSH OVERHEAD WITH DIFFLUENT FLOW
AIDING IN CLOUD EROSION EARLY MONDAY. SFC ANTI-CYCLONIC FLOW SHOULD
REMAIN TO THE SOUTH OF THE CWFA...WHICH WILL ALLOW A LIGHT WIND FROM
THE WEST TO PERSIST THROUGH THE DAY MONDAY AS WELL. TEMPS OVERNIGHT
ARE EXPECTED TO HOVER IN THE 40S...THEN DEPENDING ON WHEN CLOUDS
BEGIN TO BREAK UP EARLY MONDAY...TEMPS FALL INTO THE 30S EXCEPT
AROUND 40 CLOSER TO LAKE MICHIGAN. ENOUGH WIND SHOULD INHIBIT ANY
FROST FORMATION...SO WILL NOT MENTION THIS IN THE FORECAST FOR
TONIGHT.
THEN FOR MONDAY WITH PARTLY CLOUDY SKIES DEVELOPING AND AN 850MB
THERMAL TROUGH OF 0 TO -2 DEG C LINGERING...HIGHS WILL ONLY WARM
INTO THE LOWER 50S. POSSIBLY MID 50S ALONG THE SOUTHERN TIER OF THE
CWFA.
MONDAY NIGHT THROUGH TUESDAY...
TROUGH AXIS STEADILY DEPARTS TO THE EAST AS MID-LVL HEIGHTS CONTINUE
TO RISE. THIS WILL CONTINUE TO PROVIDE DIFFLUENT FLOW ALOFT AND KEEP
DRY AIR IN PLACE THROUGH TUESDAY. IT APPEARS POSSIBLY THAT OVERNIGHT
LOWS MON NGT INTO EARLY TUE COULD YET AGAIN APPROACH THE FREEZING
POINT FOR MANY LOCATIONS AWAY FROM LAKE MICHIGAN. TEMPS ALOFT ARE
MARGINALLY WARMER THAN THE PREVIOUS NIGHT...SO IT WILL BE POSSIBLE A
DECENT LOW LEVEL INVERSION WILL SETUP. THIS MAY ALLOW PATCHY GROUND
FOG TO DEVELOP WITH LIGHT WINDS. FOR TUESDAY A STEADY WARMING TREND
WILL BE IN FULL SWING...AS SFC TEMPS MAY CLIMB INTO THE 60S POSSIBLY
MID 60S FOR LOCATIONS SOUTH OF A LA SALLE COUNTY TO KANKAKEE COUNTY
LINE.
WEDNESDAY...
ANTI-CYCLONIC FLOW REMAINS IN CONTROL FOR MUCH OF WED. LATEST
GUIDANCE HAS BACKED OFF ON ARRIVAL OF MOISTURE. THUS IT APPEARS FOR
MUCH OF WED THE DAY WILL REMAIN DRY. SOUTHWEST WINDS AHEAD OF THIS
NEXT FRONTAL BOUNDARY AND TEMPS COULD EASILY STAY AROUND 60 TO THE
LOWER 60S FOR MUCH OF THE AREA. GUIDANCE HAS CONTINUED TO BACK OFF
ON MOISTURE ARRIVAL UNTIL WED EVENING...WHEN SHORTWAVE FINALLY
BEGINS TO ARRIVE FROM THE NORTHWEST. HAVE PUSHED PRECIP ARRIVAL BACK
UNTIL CLOSER TO 00Z THUR.
THURSDAY THROUGH SATURDAY...
MARGINAL SPREAD AMONGST ENSEMBLES FOR THE START OF THE EXTENDED
PERIOD...WITH RESPECT TO THE HIGH AMPLITUDE RIDGE PROGGED ACROSS THE
INTERIOR WEST. ACROSS THE MID-SECTION OF THE COUNTRY A FRONTAL
BOUNDARY IS POISED TO SLUGGISHLY PUSH EAST...AS A RESULT GUIDANCE
HAS SHOWN CONSIDERABLE NOISE OR LOW CONFIDENCE ON HOW TO RESOLVE
THIS FEATURE. ENSEMBLES CONTINUE TO FAVOR AMONGST MANY MEMBERS A
GRADUAL PROGRESSION OF THE BOUNDARY TO THE EAST AS THE RIDGE BUILDS
IN FRI. IT APPEARS OPERATIONAL SOLUTIONS HAVE BEEN TOO AGGRESSIVE
WITH PUSHING THE SFC RIDGE EAST LATE IN THE WEEK...AND CONTINUE TO
HINT AT A POTENT SHORT WAVE DEVELOPING ACROSS THE SOUTHERN PLAINS
FRI/SAT.
THIS LATE WEEK INTO NEXT WEEKEND SYSTEM REMAINS A FOCAL POINT
AMONGST MANY OPERATIONAL SOLUTIONS...HOWEVER ENSEMBLES HAVE BEEN
SUGGESTING MUCH OF THE OHIO VALLEY/EXTENDING WEST INTO THE MISSOURI
VALLEY WOULD REMAIN UNDER THE INFLUENCE OF ANTI-CYCLONIC FLOW IN THE
MID-LVLS. THIS WOULD FAVOR A DEFLECTION OF THIS SYSTEM TO THE
NORTHWEST ACROSS THE UPPER MIDWEST. SEVERAL DAYS STAND BETWEEN NOW
AND NEXT WEEKEND...HOWEVER THIS SYSTEM WILL CONTINUE TO BE
MONITORED. BEHIND THIS SYSTEM IT APPEARS A STRONG THERMAL TROUGH IS
DEVELOPING AND EXPECTED TO ARRIVE ACROSS THE GREAT LAKES REGION
SOMETIME OVER THE UPCOMING WEEKEND. THIS MAY LIMIT AFTN MAX TEMPS
FOR THE SECOND HALF OF THE WEEKEND IN THE 40S. LOW CONFIDENCE AT
THIS POINT ON TIMING AND INTENSITY. TEMPERATURES IN THE EXTENDED
APPEAR TO HOVER IN THE 50S...POSSIBLY APPROACHING 60 DEGREES SAT.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* VFR CEILINGS TO MOVE BACK OVER THE TERMINALS LATER THIS MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 06Z...
WEAKENING LOW PRESSURE CONTINUES TO MOVE NORTHEASTWARD TOWARD
NORTHERN LAKE MICHIGAN TONIGHT WITH A FRONTAL BOUNDARY APPROACHING
FROM THE WEST. SOUTH WINDS WILL TURN WEST YET TONIGHT AND INCREASE
SLIGHTLY LATER MONDAY MORNING. MAIN ISSUE WILL BE CIGS. VFR CIGS
ARE STARTING TO SCATTER FROM THE WEST BUT AN EXPANSIVE AREA OF VFR
CIGS IS SPREADING EASTWARD FROM IOWA AND IS EXPECTED TO MOVE
OVERHEAD OVERNIGHT. MAIN QUESTION WILL BE WHETHER THESE CLOUDS
REMAIN IN PLACE THROUGH DAYBREAK AND LOWER OR IF NEW STRATOCU
DEVELOPMENT WILL OCCUR DURING THE LATE MORNING...FOLLOWING
SCATTERING OF THE OVERNIGHT DECK...WITH BASES AROUND 3000 FT THEN
LIFT INTO THE AFTERNOON. WEST TO SOUTHWEST WINDS WILL TURN
SOUTHERLY MONDAY EVENING WITH ONLY SOME HIGH CIRRUS EXPECTED.
ONE OTHER POTENTIAL ISSUE IS FOG DEVELOPMENT TONIGHT THANKS TO HE
RAIN THAT FELL EARLIER. INDICATED PATCHY/SHALLOW FOG AT DPA/RFD
BUT CANNOT COMPLETELY RULE OUT AT THE REMAINING SITES BUT
RETURNING CLOUD COVER MAY MITIGATE THIS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* HIGH CONFIDENCE WITH VFR CEILINGS MOVING BACK OVER THE TERMINALS
WITH MEDIUM CONFIDENCE AS TO THE EXACT TIMING.
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...VFR.
WEDNESDAY...VFR WITH SHRA ARRIVING WEDNESDAY NIGHT WITH MVFR
POSSIBLE.
THURSDAY...SHRA WITH MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...VFR...CHANCE OF SHRA.
MDB
&&
.MARINE...
255 AM CDT
LOW PRESSURE ACROSS NORTHEASTERN WISCONSIN WILL MOVE INTO WESTERN
SUPERIOR THIS MORNING...BEFORE WEAKENING INTO AN OPEN TROUGH.
WINDS WILL INCREASE TOMORROW OUT OF THE SOUTH AS THE GRADIENT
TIGHTENS WITH HIGH PRESSURE EXITING TO THE EAST AND A COLD FRONT
ADVANCING FROM THE WEST. WINDS WILL LIKELY INCREASE AND PEAK JUST
BELOW GALES FOR THE OPEN WATERS...AND A SMALL CRAFT ADVISORY MAY
BE NEEDED FOR THE AFTERNOON AND EARLY EVENING HOURS ON TUESDAY FOR
THE NEARSHORE WATERS. THE COLD FRONT WILL THEN SWEEP ACROSS THE LAKE
FLIPPING WINDS AROUND TO THE NORTH OVERNIGHT ON WEDNESDAY. A WEAK
SHOT OF COLD AIR ADVECTION WILL BRING UP THE CHANCES FOR NORTHERLY
GALES ACROSS THE SOUTHERN HALF OF THE LAKE AT THAT TIME. HIGH
PRESSURE WILL THEN BUILD ACROSS THE LAKES TOWARDS THE END OF THE
WEEK AND INTO THE WEEKEND.
SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
