Area Forecast Discussion
Issued by NWS Chicago, IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 252213
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
513 PM CDT SAT APR 25 2015

.SHORT TERM...
259 PM CDT

THROUGH MONDAY...

MAIN FORECAST CHALLENGES/CONCERNS ARE WITH LINGERING SHOWERS LATE
THIS AFTERNOON INTO THE EARLY EVENING ACROSS THE SOUTHEAST TWO
THIRDS OF THE CWA...AND THEN WITH QUIETER WEATHER FOR THE
REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK.

UPPER LEVEL LOW CONTINUES TO MOVE THROUGH THE REGION THIS
AFTERNOON...AND BEGINNING TO OPEN UP AT THIS TIME. THIS SHOULD
HELP TO KICK THIS OFF TO THE EAST...WITH IT THEN LIKELY BEING
ABSORBED INTO A MUCH LARGER UPPER LEVEL SYSTEM OVER THE EASTERN
CONUS. WITH THE DEPARTURE OF THIS FEATURE AND ASSOCIATED SURFACE
LOW...HIGH PRESSURE WILL BUILD IN FROM THE NORTH. ANY REMAINING
PRECIP ACROSS THE CWA THIS AFTERNOON WILL DIMINISH FROM NORTHWEST
TO SOUTHEAST THROUGH EARLY EVENING...WITH DRY CONDITIONS AND
CLEARING SKIES THEN EXPECTED OVERNIGHT. COLDER CONDITIONS IN THE
LOW TO MID 30S ARE EXPECTED TONIGHT BUT WITH FROST NOT ANTICIPATED
AT THIS TIME...AS THE CWA WILL REMAIN ON THE FRINGE OF THIS HIGH
WITH WINDS REMAINING ELEVATED THROUGHOUT THE NIGHT.

WITH THE LARGE UPPER LEVEL SYSTEM REMAINING TO THE EAST AND WITH
UPPER LEVEL WEAKER FLOW/RIDGING OVER MUCH OF THE CENTRAL
CONUS...SURFACE HIGH WILL REMAIN SITUATED SUNDAY INTO
MONDAY...SLOWLY BUILDING. ALTHOUGH DRY CONDITIONS AND SUNNY SKIES
ARE EXPECTED SUNDAY...TEMPS WILL STILL LIKELY BE BELOW NORMAL AND
ESPECIALLY NEAR THE LAKE WITH ONSHORE FLOW. ENERGY LOOKS TO
CONTINUE TO WRAP AROUND THIS SYSTEM TO THE EAST WITH A STRONGER
PIECE OF ENERGY LIKELY MOVING SOUTH THROUGH THE CENTRAL GREAT
LAKES SUNDAY NIGHT INTO MONDAY MORNING. HOWEVER...AT THIS
TIME...IT LOOKS TO ONLY PROVIDE AN INCREASE IN CLOUD COVER OVER AT
LEAST THE EASTERN HALF OF THE CWA.

RODRIGUEZ

&&

.LONG TERM...
259 PM CDT

MONDAY NIGHT THROUGH SATURDAY...

SYSTEM TO THE EAST APPEARS TO BEGIN TO TAKE ON A MORE EASTWARD
MOVEMENT BY THE START OF THE EXTENDED PERIOD WITH ANOTHER UPPER
LOW EXPECTED TO SLOWLY SPIN OVER THE CENTRAL/SOUTHERN
PLAINS...WHILE WEAK RIDGING OCCURS OVER THE REGION. GUIDANCE IS
SHOWING SHORTWAVE ENERGY DROPPING EAST SOUTHEAST THROUGH THE UPPER
MIDWEST LATE TUESDAY TRYING TO INCH CLOSER TO THE AREA...BUT IT
LOOKS LIKE THIS WILL SLIDE JUST TO THE NORTH/NORTHEAST INTO
WEDNESDAY. SOME SLIGHT POTENTIAL FOR LIGHT RAIN LATER IN THE DAY
ON WEDNESDAY BUT UPPER LEVEL RIDGING WITH DRY CONDITIONS AND
WARMING APPEAR TO BE THE TREND THROUGH THE REST OF THE WORK
WEEK...WITH ABOVE NORMAL TEMPS BECOMING MORE LIKELY.

RODRIGUEZ

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* EAST-NORTHEAST WINDS BRIEFLY GUSTY 20-25 KT LATE THIS AFTERNOON.
  WINDS BECOME NORTHEAST AND EASE EARLY THIS EVENING.

* PATCHY LIGHT RAIN MAINLY SOUTH MLI-MDW LINE ENDING EARLY
  EVENING. SCATTERED MVFR CIGS 1500-2000 FT SOUTH AND WEST...BUT
  MAINLY VFR AND IMPROVING QUICKLY FROM THE NORTH THIS EVENING.

RATZER

//DISCUSSION...UPDATED 22Z...

SURFACE PRESSURE FALLS AND SURFACE TROUGH ASSOCIATED WITH MID-
LEVEL WAVE HAVE RESULTED IN WINDIER CONDITIONS LATE THIS AFTERNOON
WITH GUSTS AROUND 25 KTS. THIS SHOULD BE FAIRLY BRIEF WITH PASSAGE
OF TROUGH...AND OBS ALREADY SHOWING GUSTS DECREASING A BIT FROM
THE LAST 1-2 HOURS. OVERALL THROUGH THE EARLY EVENING HOURS...WINDS
WILL BACK 020-030 DEGREES THIS EVENING WITH GRADUAL DIMINISHING
TREND. LIGHT RAIN SOUTH OF ROUGHLY MLI-MDW LINE WILL END FROM THE
NORTH...WITH QUICK DRYING OF LOW LEVELS AND EROSION OF LINGERING
SCT-BKN MVFR DECK.

RATZER

PREVIOUS DISCUSSION FROM 18Z...

THE NORTHERN END OF A RAIN SHIELD STEMMING FROM A LOW PRESSURE
WELL TO THE SOUTH WILL PERSIST OVER THE AREA THIS AFTERNOON.
PERIODIC BANDS OF MODERATE RAIN AND VISIBILITY AROUND 3SM ARE
FAVORED TO MOVE OVER THE TAF SITES DURING THE FIRST HALF OF THE
AFTERNOON. CIGS WILL ALSO DROP TO AROUND 1000 FT AT THOSE
TIMES AND HAVE BEEN OBSERVED...WITH IFR CIGS OBSERVED SOUTH OF
INTERSTATE 80. BELIEVE THAT ORD IS CLOSE ENOUGH TO THE EDGE OF
THE RAIN SHIELD THAT AS LOW-LEVEL WINDS WILL PREVENT IFR CIGS FROM
REACHING THAT FAR NORTH. THEY ARE MORE POSSIBLE AT MDW AND GYY.

DRIER AIR WILL GRADUALLY FILTER IN AS THE LOW-LEVEL WINDS TURN
MORE NORTHEASTERLY. THIS WILL HELP TO DIMINISH THE RAIN INTENSITY
AS THE SYSTEM ALSO MOVES AWAY...WITH AN EXPECTED END BY SUNDOWN
AT MOST TAF SITES. CLOUD BASES SHOULD LIFT FAIRLY QUICKLY AFTER
THE RAIN HAS ENDED. THE WINDS WILL REMAIN NORTHEAST INTO SUNDAY AS
HIGH PRESSURE BUILDS SOUTHWARD ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY.

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* MEDIUM-HIGH WITH SHORT TERM WIND GUSTS.

* HIGH ALL OTHER ELEMENTS.

RATZER

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

SUNDAY NIGHT...VFR. NORTH-NORTHEAST WINDS.

MONDAY...VFR. NORTHEAST WINDS.

TUESDAY...VFR. NORTHEAST WINDS BECOMING EAST.

WEDNESDAY...SLGT CHC -RA. BRIEF MVFR POSSIBLE. NORTH-NORTHWEST
WINDS BECOMING NORTHEAST.

THURSDAY...VFR. NORTH-NORTHEAST WINDS.

FRIDAY...VFR.

MTF/KJB

&&

.MARINE...
137 PM CDT

MODERATE NORTHERLY FLOW WILL PERSIST THROUGH MONDAY...PARTICULARLY
SOUTHERN PORTIONS OF THE LAKE AS GRADIENT REMAINS RATHER TIGHT
BETWEEN HIGH OVER CANADA AND LOW PASSING WELL SOUTH OF THE LAKES.
WEAK GRADIENT OVER THE LAKE THROUGH MUCH OF THE REMAINDER OF THE
UPCOMING WORK WEEK WITH WINDS DOMINATING BY LAKE/LAND BREEZE
CIRCULATIONS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 10 AM MONDAY.

&&

$$

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.