Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 161348
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
848 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 14Z...

* NONE.

KB

//DISCUSSION...UPDATED 12Z...

HIGH PRESSURE WILL RESULT IN LIGHT WINDS AND PRIMARILY VFR
CONDITIONS THROUGH THE FORECAST PERIOD...WITH THE EXCEPTION OF SOME
PATCHY GROUND FOG DURING THE EARLY MORNING HOURS MAINLY AT THE
OUTLYING TERMINALS. WINDS WILL GENERALLY BE SOME SORT OF
NORTHWESTERLY DIRECTION THROUGH MIDDAY THOUGH THERE WILL LIKELY BE
VARIABILITY DUE TO THE LIGHT MAGNITUDE. WINDS SHOULD FAVOR A MORE
WESTERLY DIRECTION THIS AFTERNOON/EVENING. A LAKE BREEZE IS POSSIBLE
THIS AFTERNOON...THOUGH WEAK THERMAL CONTRAST AND OPPOSING FLOW
SHOULD KEEP IT FROM PUSHING IN ACROSS THE TERMINALS.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH WITH ALL FORECAST ELEMENTS.

KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.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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