Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 161929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
229 PM 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 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

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

* HIGH FOR ALL ELEMENTS.

KJB

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

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

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

KMD

&&

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

$$

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