Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 201955
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CDT MON OCT 20 2014

.DISCUSSION...
249 PM CDT

TONIGHT...
UPPER LEVEL WAVE CONTINUES TO ROTATE OVER NORTHEAST ONTARIO...WITH A
A COUPLE WEAK LOBES OF VORTICITY ROTATING AROUND THE BACKEDGE OF
THIS SYSTEM...PUSHING SOUTH INTO THE NORTHERN GREAT LAKES. VISIBLE
IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS MICHIGAN...STRETCHING
WEST ACROSS THE LAKE AND BEGINNING TO SLIDE INTO FAR NORTHEAST IL.
GUIDANCE SUGGESTS A FEW LIGHT SHOWERS WILL ACCOMPANY THIS WAVE AS IT
PUSHES SOUTHEAST ACROSS WISCONSIN AND PERHAPS INTO FAR NORTHEAST IL
LATE THIS EVE...BEFORE SHIFTING EAST INTO FAR NORTHWEST IN BY
DAYBREAK TUE. OTHERWISE EXPECT CLOUDS TO THICKEN THIS EVE ACROSS THE
CWFA...PERHAPS LESS CLOUD COVER ACROSS THE FAR WEST/SOUTHWEST
PORTIONS OF THE FORECAST AREA. WITH THE CLOUD COVER TONIGHT...THIS
SHOULD KEEP TEMPS GENERALLY AROUND 40 TO THE LOW 40S TONIGHT.

TUESDAY THROUGH THURSDAY...
500MB TROUGH AXIS WILL BEGIN TO PUSH EAST...WITH A HIGH AMPLITUDE
RIDGE BEGINNING TO BUILD INTO THE REGION FROM THE CENTRAL PLAINS.
THIS WILL BRING A BROAD SFC RIDGE TO THE AREA STRETCHING FROM
CENTRAL CANADA SOUTH TO THE WESTERN GULF. GUIDANCE THEN CONTINUES TO
MAINTAIN THIS FEATURE THROUGH THUR MORNING...HOWEVER THERE IS A WEAK
WAVE SLIDING EAST ACROSS THE CENTRAL CONUS WED NGT THAT IS PROGGED
TO LIFT NORTHEAST OF THE CWFA THUR AFTN/EVE. THIS SYSTEM COULD BRING
SOME LIGHT PRECIP TO THE AREA...BUT AT THIS TIME HAVE ONLY GONE WITH
SLIGHT CHANCE OF POPS GIVEN THE MOISTURE AVAILABILITY APPEARS TO BE
MINIMAL. TEMPS WILL GENERALLY BE IN THE UPR 50S TO LOW 60S...WITH
OVERNIGHT LOWS IN THE MID 30S TO MID 40S.

FRIDAY THROUGH MONDAY...
ENSEMBLES CONTINUE TO FEATURE A TROUGH PERSISTING ALONG THE FAR
SOUTHWEST CONUS...ALLOWING RIDGING TO DOMINATE THE CENTRAL CONUS
LATE IN THE WEEK INTO THE WEEKEND. THIS WILL LIKELY CONTINUE THE DRY
PATTERN FOR THE REGION. IN ADDITION IT APPEARS TEMPS WILL BE ABLE TO
STEADILY MODERATE...PERHAPS REACHING THE UPR 60S TO ARND 70.

ENSEMBLES DO SUGGEST THAT TOWARDS THE SECOND HALF OF THE WEEKEND THE
RIDGE WILL BEGIN TO DRIFT EAST...WITH A TROUGH DIGGING INTO THE
CENTRAL CONUS AND PERHAPS BRINGING UNSETTLED WEATHER BACK INTO THE
REGION EARLY NEXT WEEK.


BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NORTHWEST WINDS/GUSTS BRIEFLY BECOMING MORE NORTHERLY THIS
  AFTERNOON...THEN BECOMING NORTHEAST WITH SPEEDS AT OR ABOVE 10
  KT TUESDAY MORNING.

* DEVELOPING VFR CEILINGS BECOMING MVFR EARLY TUESDAY MORNING.

* PERIODIC/ISOLATED LIGHT SHOWERS.

RODRIGUEZ

//DISCUSSION...UPDATED 18Z...

MOSTLY CLEAR SKIES STILL PRESENT ACROSS THE TERMINALS EARLY THIS
AFTERNOON...WHILE NORTHWEST WINDS CONTINUE TO SLOWLY INCREASE.
DEVELOPING DIURNAL STRATOCU WILL SPREAD OVER THE AREA OVER THE
NEXT 1-2 HOURS AND ALTHOUGH THERE MAY BE A BRIEF PERIOD OF HIGH
END MVFR CEILINGS...DO THINK THAT VFR CEILINGS WILL PREVAIL THIS
AFTERNOON. NORTHWEST WINDS/GUSTS WILL STEADILY INCREASE OVER THE
NEXT COUPLE OF HOURS WITH A POSSIBILITY REMAINING FOR WINDS TO
BRIEFLY GO MORE NORTHERLY. THIS SHOULD ALSO BE BRIEF WITH A
NORTHWEST WIND LIKELY FAVORED. WITH VFR CEILINGS REMAINING
OVERHEAD TONIGHT...THE NORTHWEST WINDS WILL DIMINISH BEFORE
QUICKLY INCREASING ABOVE 10 KT OUT OF THE NORTHEAST EARLY TUESDAY
MORNING. AS THIS OCCURS...ANTICIPATE ALREADY PRESENT MVFR CEILINGS
OVER THE LAKE TO MOVE WEST ACROSS THE TERMINALS...EXCEPT RFD.
THERE WILL ALSO BE A PERIOD OF SCATTERED LIGHT SHOWERS TO SPILL
OFF THE LAKE DURING THIS TIME...BUT WITH MDW/GYY THE LIKELY
LOCATIONS TO OBSERVE THIS PRECIP.

RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

* HIGH CONFIDENCE WITH VFR CEILINGS...MEDIUM CONFIDENCE WITH MVFR
  CEILINGS.

* MEDIUM CONFIDENCE WITH LIGHT SHOWERS.

RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...

* TUESDAY NIGHT...DRY/VFR.
* WEDNESDAY...DRY/VFR. EAST/NORTHEAST WINDS.
* THURSDAY...DRY/VFR. SOUTH WINDS.
* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. WEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.

&&

.MARINE...

250 PM...LOW PRESSURE CONTINUES TO INFLUENCE THE REGION CENTERED
OVER NORTHERN LAKE HURON LATE THIS AFTERNOON AND IS EXPECTED TO
SLOWLY DRIFT EAST OVERNIGHT. THIS LOW WILL THEN REACH LAKE ONTARIO
AROUND DAYBREAK TUE. THE BACK EDGE OF THIS LOW CONTINUES TO
FEATURE A TIGHTENING PRESSURE GRADIENT...WHICH HAS PRODUCED GUSTY
WINDS JUST BEGINNING TO SLIDE OVER THE NORTHERN PORTIONS OF THE
LAKE. THESE GUSTY WINDS WILL EVENTUALLY SLIDE SOUTH THIS
EVENING...AND EXPECT NORTH GUSTS UP TO 30 KTS. HIGH PRESSURE OVER
ONTARIO WILL BEGIN TO BUILD SOUTH OVERNIGHT...THEN STRETCH FROM
ONTARIO SOUTH TO THE WESTERN GULF OF MEXICO BY TUE NGT. THIS WILL
BRING MUCH LIGHTER WINDS TO THE LAKE BY WED.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...10 PM MONDAY TO 7 AM WEDNESDAY.

&&

$$

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