Area Forecast Discussion
Issued by NWS Chicago, IL

Home | Current Version | Previous Version | Text Only | 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 291959
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
259 PM CDT SAT AUG 29 2015

.SHORT TERM...

TONIGHT AND SUNDAY...

248 PM...FORECAST CONCERNS ARE DENSE FOG POTENTIAL TONIGHT...
LINGERING PRECIP TONIGHT AND ISOLATED THUNDERSTORMS SUNDAY
AFTERNOON.

WHILE MUCH OF THE PRECIP HAS ENDED THIS AFTERNOON WITH JUST SOME
SCATTERED SHOWERS ACROSS NORTHEAST IL AND NORTHWEST INDIANA...THERE
REMAINS THE POTENTIAL FOR SHOWERS INTO THIS EVENING MAINLY ACROSS
THE EASTERN HALF OR SO OF THE CWA. MAINTAINED CHANCE POPS SLOWLY
DROPPING OFF INTO THIS EVENING THOUGH OVERALL COVERAGE OF PRECIP
TRENDS IS A BIT UNCERTAIN. ANY LINGERING SHOWERS OVERNIGHT INTO
EARLY SUNDAY MORNING SHOULD BE CONFINED TO THE FAR SOUTHEAST CWA.

AS THE LOW NOW OVER WESTERN IL CONTINUES TO DISSIPATE...THE GRADIENT
WILL BECOME QUITE WEAK TONIGHT WITH WINDS ALREADY SHIFTING TO LIGHT
EAST/NORTHEAST ACROSS SOUTHEAST WI AND FAR NORTHEAST IL WHERE LOWER
CLOUDS AND SOME LIGHT FOG HAS DEVELOPED. MODEL FOG/VIS GUIDANCE ALL
SHOW FOG DEVELOPING IN THESE AREAS THIS EVENING THEN SPREADING TO
THE WEST/SOUTHWEST OVERNIGHT INTO SUNDAY MORNING. WITH MOS GUIDANCE
SHOWING MANY LOCATIONS TANKING OVERNIGHT. WITH THE LOW LEVELS
ALREADY SATURATED...THIS TREND SEEMS REASONABLE AND ADDED DENSE FOG
OVER NORTHWEST IL...MAINLY NORTHWEST OF AN ORD TO VYS LINE. WITH
LATE AUGUST SUNSHINE...EXPECT THIS TO BURN OFF BY MID MORNING
SUNDAY WITH CLOUDS SCATTERING OUT BY AFTERNOON. ASSUMING THIS
OCCURS...TEMPS SHOULD BE ABLE TO WARM INTO THE LOWER 80S. THOUGH A
LAKE BREEZE WILL LIKELY KEEP THE LAKESHORE AREAS COOLER.

AS TEMPS WARM...ESPECIALLY IN THE SOUTHEAST WHERE LESS FOG IS
EXPECTED...ENOUGH INSTABILITY IS PRESENT FOR ISOLATED SHOWERS AND
POSSIBLY A THUNDERSTORM. THIS SHOULD BE MAINLY DIURNALLY DRIVEN
FROM EARLY AFTERNOON TO EARLY EVENING THOUGH WITH MINIMAL
FORCING...PRECIP MAY END UP QUITE SPARSE. CMS

&&

.LONG TERM...
328 AM CDT

MONDAY THROUGH FRIDAY...

STRONGER WESTERLIES WILL BE SITUATED WELL NORTH OF THE REGION
BEGINNING OF THE PERIOD...WITH RIDGING/WEAKER FLOW ACROSS THE
AREA. CONTINUED WARMING TREND WILL CONTINUE EARLY NEXT WEEK WITH
MID TO UPPER 80S LIKELY ON MONDAY...WITH TEMPS LIKELY APPROACHING
90 FOR MOST LOCATIONS ON TUESDAY AND WEDNESDAY. WITH INCREASING
MOISTURE/INSTABILITY DURING THE PERIOD...AFTERNOON THUNDERSTORMS
DO APPEAR POSSIBLE THROUGHOUT THE WEEK. HAVE TRIED TO INDICATE
BEST CHANCES DURING THIS NEXT WEEK...BUT WITH THESE POPS LIKELY
BEING REFINED WITH LATER FORECASTS. HOWEVER...WOULD THINK MOST
LOCATIONS WILL REMAIN ON THE DRY SIDE WITH ANY DEVELOPMENT MORE
THAN LIKELY ISOLATED TO WIDELY SCATTERED.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* ISO SHOWERS THROUGH 22Z.

* LGT SOUTH WINDS BECOMING VARIABLE AFT 00Z TO NORTHEAST LESS THAN
  4KT.

* CIGS LOWERING TO IFR AND POSSIBLY LIFR. IN ADDITION FOG IS
  EXPECTED TO DEVELOP AND LOWER VSBYS TO ARND 1SM.

BEACHLER

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

VISIBLE SATELLITE IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS
THE REGION...WITH SURFACE OBSERVATIONS INDICATING VERY LIGHT
WINDS. A WEAK FRONTAL BOUNDARY WAS ORIENTED ACROSS NORTHEAST IL
STRETCHING SOUTHWEST...WITH WIND DIRECTIONS BECOMING VARIABLE ON
EITHER SIDE OF THIS BOUNDARY THIS AFTERNOON. A FEW SHOWERS
CONTINUE TO LINGER WITH SOME EMBEDDED THUNDER NEAR ORD...HOWEVER
IT APPEARS THUNDER WILL BE ENDING BY 20Z AND SHOWERS WILL SLOWLY
DISSIPATE IN COVERAGE THROUGH THE REMAINDER OF THE AFTERNOON.
GUIDANCE INDICATES CIGS WILL QUICKLY LOWER ARND 00Z OR SHORTLY
AFT...NEARING IFR AND POSSIBLY TRENDING FURTHER TOWARDS LIFR.
WINDS WILL REMAIN LIGHT OVERNIGHT...WHICH WILL ALLOW FOG AND LOW
CIGS TO LINGER THRU DAYBREAK. AREAS OF DENSE FOG ARE EXPECTED TO
DEVELOP AS WELL...BUT SHOULD REMAIN WEST OF ORD/MDW. AT THIS TIME
HAVE OPTED TO INCLUDE MENTION OF 1/4SM FOG AT DPA/RFD IN CURRENT
TAF.

BEACHLER

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN WIND DIR/SPEED.

* HIGH CONFIDENCE IN CIGS LOWERING TOWARDS IFR...MEDIUM CONFIDENCE
  IN TIMING AND LIFR CIGS DEVELOPING.

* MEDIUM/HIGH CONFIDENCE IN PRECIP ENDING AT ORD/MDW BY 20Z.

* MEDIUM/HIGH CONFIDNECE IN VSBYS LOWERING TO MVFR...LOW
  CONFIDENCE IN VSBYS LOWERING TO IFR.

BEACHLER

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

SUNDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR. MOSTLY LIGHT
SOUTHERLY WINDS...THOUGH AFTERNOON LAKE BREEZES COULD SHIFT WINDS
TO EAST OR SOUTHEAST DURING AFTERNOONS.

IZZI

&&

.MARINE...
207 AM CDT

NARROW RIDGE OF HIGH PRESSURE STRETCHING FROM NEAR DETROIT TO
GREEN BAY COMBINED WITH WEAKENING LOW PRESSURE OVER IOWA WILL
RESULT IN A NARROW RIBBON OF STRONGER EASTERLY WINDS EARLY THIS
MORNING OVER PORTIONS OF CENTRAL LAKE MICHIGAN BEFORE BACKING MORE
SOUTHEAST LATER THIS MORNING THEN ULTIMATELY EASING THIS
AFTERNOON. WEAK LOW OVER IOWA WILL DISSIPATE TONIGHT AND REMAINDER
OF THE UPCOMING WEEK WILL SEE WEATHER OVER THE LAKE DOMINATED BY
HIGH PRESSURE ANCHORED OVER THE MID ATLANTIC AND NORTHEAST.

IZZI

&&

.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.