Area Forecast Discussion
Issued by NWS Chicago, IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLOT 210819
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
319 AM CDT THU MAY 21 2015

.SHORT TERM...
317 AM CDT

THROUGH TONIGHT...

RIDGE OF HIGH PRESSURE IS IN PLACE ACROSS NORTHERN ILLINOIS EARLY
THIS MORNING WHILE AN EAST-WEST ORIENTED TROUGH CURRENTLY OVER
LAKE SUPERIOR WILL SLOWLY SLIDE SOUTH ACROSS LAKE MICHIGAN TODAY
AND TONIGHT. MEANWHILE...WATER VAPOR IMAGERY SHOWS A SHORTWAVE
TROUGH PUSHING ESE ACROSS IA/MN EARLY THIS MORNING. PATCHY
LINGERING LIGHT RAIN/SPRINKLES MAINLY OVER THE EASTERN PORTIONS OF
THE CWA WILL CLEAR OUT EARLY TO MID MORNING AND CLEARING SKIES
SHOULD ADVANCE FROM THE NORTHWEST AS THIS WAVE PASSES OVERHEAD
WITH SUBSIDENCE SETTING IN BEHIND. EXPECT MOSTLY SUNNY CONDITIONS
ACROSS THE AREA BY THIS AFTERNOON. MID LEVEL WARM ADVECTION AND
DEEP MIXING TODAY WILL HELP PUSH TEMPS 15 TO 20 DEGREES WARMER
COMPARED TO YESTERDAY`S HIGH TEMPS...TOPPING OUT IN THE MID TO
UPPER 60S. SYNOPTIC WINDS SHOULD BE JUST STRONG ENOUGH TO STAVE
OFF ANY LAKE BREEZE FROM PUSHING INLAND...SO EXPECT THE WARMER
TEMPS TO SPREAD RIGHT UP TO THE LAKE. THE AFOREMENTIONED SURFACE
TROUGH MOVING SOUTH ACROSS THE GREAT LAKES TODAY WILL ARRIVE IN
NORTHERN ILLINOIS OVERNIGHT...MOVING INTO THE CWA AROUND MIDNIGHT.
EXPECT A MODEST BOOST FROM THE LAKE OVERNIGHT WITH WINDS SWINGING
AROUND TO THE NORTHEAST AND TEMPS FALLING BACK INTO THE LOW TO MID
40S BEHIND.


&&

.LONG TERM...
255 AM CDT

FRIDAY THROUGH WEDNESDAY...

FRIDAY LOOKS TO BE SUNNY AND MILD AWAY FROM THE LAKE...THOUGH
NORTHEAST WINDS OFF THE LAKE IN THE WAKE OF THE BACK DOOR FRONT WILL
HOLD TEMPS ALONG THE SHORE IN THE 50S.

HIGH PRESSURE OVER THE WESTERN LAKES REGION FRIDAY WILL MOVE RATHER
SWIFTLY TO THE SOUTHEAST AND OFF THE MID ATLANTIC COAST BY SATURDAY
EVENING. BROAD SWATH OF SOUTHERLY WINDS ON THE BACK SIDE OF THAT
HIGH WILL BEGIN THE PROCESS OF DRAWING MODIFIED GULF MOISTURE
NORTHWARD TOWARD THE REGION. UPPER RIDGE WILL BE POSITIONING ITSELF
OVERHEAD SATURDAY...SO IT LOOKS DRY AND WARMER THOUGH SLIGHT LAKE
BREEZE COULD KEEP MAINLY ILLINOIS SHORE A BIT COOLER SATURDAY
AFTERNOON.

NOT SHOCKINGLY...GFS HAS SLOWED THE EASTWARD PROGRESSION OF THE BIG
WESTERN TROUGH AND NOW WOULD SUGGEST A MUCH DRIER SUNDAY OVER THE
AREA WHILE ECMWF AND GEM STILL LOOK WETTER. REALLY THE ENTIRE PERIOD
SUNDAY THROUGH WEDNESDAY LOOKS TO BE PRETTY SIMILAR FORECAST-WISE
WITH DISTURBED SOUTHWEST FLOW ALOFT OVER THE AREA AND LOW LEVEL
BAROCLINIC ZONE NEAR ENOUGH BY TO PUT US IN THE POTENTIAL ZONE OF
SHOWERS AND THUNDERSTORMS. WHILE MODERATE-HIGH POPS ARE GOING TO BE
CARRIED THROUGH THE PERIOD...IT IS ALSO QUITE LIKELY THERE WILL BE
MANY DRY HOURS THOUGH ALSO THE THREAT OF AT LEAST OCCASIONALLY
LOCALLY HEAVY RAINFALL. TEMPERATURES SHOULD GENERALLY BE RATHER WARM
AND MUGGY...ONLY POTENTIAL FLY IN THE TEMP OINTMENT WOULD BE ANY
SOUTHWARD DISPLACEMENT OF THE FRONT BY ANY MORE ORGANIZED MCS
ACTIVITY WHICH OFTEN ISN`T TERRIBLY WELL PREDICTED A COUPLE/FEW DAYS
OUT LET ALONE A WEEK OUT.

IZZI

&&

.AVIATION...

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

* WINDS TURNING NORTHEAST IN THE PREDAWN HOURS FRIDAY.

BMD

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

RIDGE OF HIGH PRESSURE LIES SOUTH OF THE TERMINALS TONIGHT WHILE
A COLD FRONT IS IN PLACE ACROSS THE NORTHERN GREAT LAKES REGION.
RELATIVELY QUIET CONDITIONS WILL BE IN PLACE THROUGH THE TAF
PERIOD UNDER THE INFLUENCE OF THE RIDGE WHICH WILL PROVIDE VFR
CONDITIONS AND LIGHT WEST FLOW. DURING THE DAY THURSDAY...MIXING
WILL ALLOW WINDS TO PICK UP SOME WITH GUSTS INTO THE MID TO HIGH
TEENS. THE COLD FRONT WILL MAKE ITS WAY DOWN LAKE MICHIGAN THROUGH
THE PERIOD AND WILL DROP ACROSS THE TERMINALS LATE THURSDAY
NIGHT/EARLY FRIDAY MORNING TURNING WINDS TO THE NORTHEAST.

BMD

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

* MEDIUM-HIGH ON WINDS THROUGH THURSDAY...BUT MEDIUM THURSDAY
  EVENING/NIGHT.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* FRIDAY...DRY/VFR. NORTHEAST WINDS.
* SATURDAY...DRY/VFR. SOUTH WINDS.
* SUNDAY...SHRA LIKELY. CHANCE OF TSRA. MAINLY VFR. SOUTH WINDS.
* MONDAY...SHRA/TSRA LIKELY. MVFR POSSIBLE. GUSTY SOUTHWEST WINDS.
* TUESDAY...CHANCE OF SHRA/TSRA. MAINLY VFR. GUSTY SOUTHWEST WINDS.

&&

.MARINE...
317 AM CDT

HIGH PRESSURE LIES SOUTH OF THE LAKE THIS MORNING WHILE AN EAST-
WEST ORIENTED TROUGH OF LOW PRESSURE LIES ACROSS LAKE MICHIGAN.
SOUTHWEST/WEST WINDS OF 15 TO 20 KT WILL BE IN PLACE AHEAD OF THE
TROUGH TODAY AS IT SLOWLY SLIDES SOUTH ACROSS THE LAKE. BEHIND THE
TROUGH WINDS WILL VEER TO THE NORTH/NORTHEAST AND BRIEFLY REMAIN
ELEVATED IN THE 15 TO 20 KT RANGE. WINDS THEN SHOULD BEGIN TO
FRIDAY AS HIGH PRESSURE BUILDS BACK ACROSS THE REGION. LAKE
BREEZES ARE EXPECTED FRIDAY AFTERNOON AND EVENING. SOUTHWEST WINDS
RETURN SATURDAY AS THE HIGH SHIFTS EAST OF THE LAKE AND LOW
PRESSURE DEVELOPS OVER THE PLAINS.

BMD

&&

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

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.