Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 160859
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
359 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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