Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 230745
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
245 AM CDT THU OCT 23 2014

.DISCUSSION...
310 PM CDT

SHORT TERM...THIS AFTERNOON THROUGH TONIGHT...FOR THE REMAINDER OF
THE AFTERNOON AND TONIGHT...MOSTLY CLEAR SKIES AND SLIGHTLY HIGHER
TEMPERATURES ARE MAKING FOR A TRANSITION DAY TODAY BEFORE A MORE
NOTABLE WARMING TREND EXPECTED FOR THE NEXT FEW DAYS. UNDER THE
CLEAR SKIES AND LIGHT WINDS...TEMPERATURES THIS AFTERNOON ARE
CLIMBING INTO THE LOW 50S NEAR LAKE MICHIGAN TO AROUND 60F WELL
INLAND.  A RIDGE OF HIGH PRESSURE MOVING ACROSS THE WESTERN GREAT
LAKES HAS SET UP LIGHT ONSHORE FLOW NEAR THE LAKE...PREVENTING THE
WARMER CONDITIONS NEAR THE LAKE.  FOR TONIGHT...UNDER CLEAR
SKIES...LIGHT WINDS AND WITH A RELATIVELY DRY AIRMASS IN
PLACE...TEMPERATURES WILL ONCE AGAIN HAVE AN OPPORTUNITY TO RADIATE
DOWN INTO THE MIDDLE TO UPPER 30S.  THE HIGHLY URBANIZED AREAS OF
THE CHICAGO METRO AREA SHOULD REMAIN A BIT WARMER...WITH LOWS ONLY
IN THE LOWER 40S.  EVEN THOUGH THE AIRMASS IS EXPECTED TO BE
RELATIVELY DRY...DEWPOINTS SHOULD BE THE LOWER TO MIDDLE 30S...SO
TEMPERATURES WILL LIKELY RADIATE CLOSE TO THE DEWPOINTS.  DO NOT
ANTICIPATE WIDESPREAD DENSE FOG...BUT RATHER THERE COULD MORE LIKELY
BE SOME PATCHY...SHALLOW GROUND FOG IN LOW-LYING...SHELTERED...RURAL
LOCATIONS.

LONGER TERM...THURSDAY THROUGH WEDNESDAY...AS THE HIGH SLIDES OFF TO
THE EAST AND A SFC TROUGH AND ASSOCIATED COLD FRONT CROSS THE
CENTRAL PLAINS...A RETURN FLOW OF SLIGHTLY WARMER...MOISTER AIR WILL
SET UP.  WHILE THE NORTHERN PORTION OF THE SFC HIGH WILL PUSH WELL
EAST OF THE AREA...THE MIDWEST WILL REMAIN CUT OFF FROM THE RICHER
GULF MOISTURE AS A RIDGE AXIS EXTENDS SWWD THROUGH ERN TX.  THIS
COMBINATION WILL AFFECT BOTH MAX TEMP POTENTIAL FOR THE DAY AS WELL
AS PCPN POTENTIAL WITH THE PASSAGE OF THE COLD FRONT.  WHILE
INCREASING CLOUD COVER WILL SOMEWHAT TEMPER THE POTENTIAL MAX TEMPS
FOR THE DAY...HIGHS THURSDAY SHOULD RANGE FROM THE UPPER 50S TO
AROUND 60F.  AS FOR PCPN POTENTIAL...THERE SHOULD BE ADEQUATE SFC
FORCING WITH THE COLD FRONT AS WELL AS MID LEVEL FORCING FROM A NRN
STREAM SHORTWAVE TRACKING ACROSS THE UPPER MISSISSIPPI VALLEY AND
WRN GREAT LAKES AS WELL AS SOME PHASING WITH A SRN STREAM SHORTWAVE
PASSING ACROSS THE MIDDLE MISSISSIPPI VALLEY.  EVEN THOUGH THE
SURFACE LAYER WILL BE SOMEWHAT CUT OFF FROM THE RICHEST LOW LEVEL
GULF MOISTURE...THE SRN STREAM SHORT WAVE WILL BRING SOME ENHANCED
MID LEVEL MOISTURE...SO THE OVERALL MOISTURE PROFILE WILL STILL BE
RELATIVELY MOIST WITH THE MODELS INDICATING PWATS OF AROUND 1 INCH
WITH THE FROPA.  SO...EXPECT THAT ENTIRE CWA SHOULD SEE WETTING
RAINFALL THROUGH THE DAY TOMORROW...POSSIBLY LINGERING INTO TOMORROW
EVENING OVER THE FAR ERN PORTIONS OF THE CWA...THE STEADILY
PROGRESSIVE NATURE OF THE SYSTEM SHOULD LIMIT RAINFALL AMOUNTS TO
ARND A TENTH TO A QUARTER OF AN INCH WITH SOME OF THE HEAVIER
SHOWERS.  MODELS SOUNDINGS INDICATE LITTLE OR NO CAPE...SO THUNDER
SHOULD NOT BE AN ISSUE.

FOLLOWING THE PASSAGE OF THE FRONT...THE REAL WARMING TREND WILL
BEGIN IN EARNEST ON FRIDAY AS UPPER RIDGING BUILDS ACROSS THE
ROCKIES AND INTO THE WESTERN PLAINS...WHILE THE UPPER TROUGH AND
COLD FRONT MOVE TO THE EAST COAST.  BY FRIDAY...850MB TEMPS ARND 15C
WILL MOVE ACROSS THE AREA AND EXPECT THAT TEMPS SHOULD REACH INTO
THE MIDDLE TO UPPER 60S.  BY SATURDAY...THE THERMAL AXIS WILL SHIFT
TO THE SOUTH...ACROSS CNTRL/SRN IL/IN WHILE A DEEP UPPER LOW TRACKS
ACROSS THE UPPER GREAT LAKES.  THIS WILL LEAD TO MORE NWLY FLOW
ACROSS THE UPPER MIDWEST...AND POSSIBLY LIMITING WARMING ACROSS THE
NRN PORTIONS OF THE AREA...SO...WILL CARRY TEMPS IN THE LOWER TO
MIDDLE 60S NORTH OF THE I-80 CORRIDOR WITH TEMPS IN THE UPPER 60S
ACROSS THE SRN PORTIONS OF THE CWA.  WITH ENOUGH SUNSHINE...SOME 70F
MAX TEMPS ARE NOT OUT OF THE QUESTION FOR LOCATIONS SOUTH OF A
PONTIAC TO REMINGTON LINE.  THE RELATIVELY WARM AND DRY WEATHER WILL
PERSIST THROUGH THE WEEKEND AS THE UPPER RIDGE SLOWLY PROGRESSES
ACROSS THE CENTRAL CONUS.

THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL EARLY NEXT
WEEK WHEN THE UPPER RIDGE BUILDS TO THE EAST COAST AND A STRONG
PACIFIC SHORTWAVE DROPS FROM THE PACIFIC NORTHWEST TO THE FOUR
CORNERS AREA BY MONDAY AFTERNOON.  THIS WILL SET UP STRONG SWLY FLOW
ALOFT...WITH A TRAIN OF SOUTHERN STREAM SHORTWAVE ENERGY...WHILE AN
OPEN GULF OF MEXICO EVOLVES AT THE SURFACE.  INCREASED LOW LEVEL
MOISTURE AND MID LEVEL SHORT WAVE ENERGY WILL BRING A CHANCE FOR
SHOWERS AND POSSIBLY SOME THUNDERSTORMS FOR MONDAY NIGHT AND INTO
TUESDAY.  THE UNSEASONABLY HIGH TEMPERATURES WILL COME TO AN END BY
EARLY NEXT WEEK AS ANOTHER COLD FRONT IS EXPECTED TO CROSS THE
REGION.  THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THIS FRONT
SHOULD PUSH THROUGH THE AREA BY TUESDAY NIGHT OR WEDNESDAY...
BRINGING MAX TEMPS BACK INTO THE 50S.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* SOUTHERLY WINDS 10-12 KTS MID MORNING THRU LATE AFTERNOON.
* CHANCE OF SHRA LATE AFTERNOON/EARLY EVENING.
* MVFR CIGS TONIGHT. CMS

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

A WEAK COLD FRONT/TROUGH WILL MOVE ACROSS THE AREA LATER THIS
AFTERNOON AND THIS EVENING...AS IT WEAKENS. LIGHT SOUTHEAST WINDS
WILL TURN MORE SOUTH/SOUTHWEST BY MID MORNING AND INCREASE INTO
THE 10-12KT RANGE WITH SOME HIGHER GUSTS POSSIBLE THRU EARLY
AFTERNOON. SHOWERS ARE EXPECTED TO SPREAD INTO NORTHWEST IL BY
EARLY AFTERNOON AND THEN ACROSS THE REST OF THE AREA BY LATE
AFTERNOON AND EARLY EVENING. NO CHANGE TO TIMING WHICH LOOKS ON
TRACK BUT OVERALL COVERAGE AND INTENSITY REMAINS SOMEWHAT LOWER
AT THE CHICAGO AREA TERMINALS AND BACKED OFF TO VICINITY MENTION
FOR NOW. CIGS SHOULD REMAIN VFR UNTIL THE SHOWERS END AND THEN
LOWER TO MVFR THIS EVENING...EARLIER AT RFD. AS CLOUDS CLEAR FROM
WEST TO EAST LATE TONIGHT/EARLY FRIDAY MORNING...SOME FOG WILL BE
POSSIBLE. CMS

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH FOR WIND DIRECTION...MEDIUM FOR SPEEDS AND POSSIBLE GUSTS.
* MEDIUM FOR SHRA LATE AFTERNOON/EARLY EVENING.
* MEDIUM FOR MVFR CIGS TONIGHT. CMS

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

* FRIDAY...DRY/VFR. SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. GUSTY NORTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTH WINDS.
* TUESDAY...CHANCE OF SHRA. STRONG/GUSTY WESTERLY WINDS.

KMD

&&

.MARINE...

245 AM...FAIRLY ACTIVE PATTERN IS EXPECTED INTO EARLY NEXT WEEK.
HIGH PRESSURE EXTENDING FROM QUEBEC SOUTHWEST THROUGH THE CENTRAL
LAKES REGION WILL SPLIT TODAY...WITH THE HIGH WEAKENING AND MOVING
SOUTH INTO THE OHIO VALLEY TONIGHT. LOW PRESSURE OVER MANITOBA
WILL MOVE NORTH TODAY AS A WEAK COLD FRONT APPROACHES THE WESTERN
LAKES. THE GRADIENT WILL TIGHTEN SOME TODAY AHEAD OF THIS FRONT...
BUT THE FRONT IS EXPECTED TO DISSIPATE OVER THE WESTERN LAKES
TONIGHT. THUS WINDS MAY SHIFT WESTERLY FOR A TIME BUT WILL QUICKLY
GO BACK SOUTHWEST BY FRIDAY MORNING.

THE LOW LIFTING NORTH OVER MANITOBA WILL BE ABSORBED BY A STRONGER
LOW MOVING ACROSS CENTRAL CANADA TONIGHT AND FRIDAY. THIS LOW WILL
THEN MOVE ACROSS ONTARIO REACHING JAMES BAY SATURDAY AFTERNOON AS
IT DEEPENS. ANOTHER COLD FRONT TRAILING THIS LOW WILL MOVE ACROSS
LAKE MICHIGAN LATE FRIDAY NIGHT INTO SATURDAY MORNING. AHEAD OF
THIS FRONT...SOUTHERLY WINDS WILL INCREASE AGAIN. BEHIND THE FRONT
WINDS WILL SHIFT NORTHWEST 20-25KTS AND MAY APPROACH 30 KTS FOR A
TIME SATURDAY AFTERNOON INTO SATURDAY EVENING.

A WEAK RIDGE WILL MOVE FROM THE PLAINS SATURDAY TO THE WESTERN
LAKES SUNDAY...WITH WINDS QUICKLY SHIFTING FROM WEST SUNDAY
MORNING TO SOUTH/SOUTHEAST SUNDAY EVENING. THE GRADIENT WILL THEN
TIGHTEN WITH INCREASING SOUTHERLY WINDS AS A LARGE AREA OF LOW
PRESSURE DEVELOPS OVER THE PLAINS SUNDAY INTO MONDAY. CMS

&&

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

$$

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