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

836
FXUS63 KLOT 061522
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1022 AM CDT FRI MAY 6 2016

.UPDATE...
1014 AM CDT

THE ONLY CHANGE TO THE FORECAST TODAY WAS TO ADD IN SOME
SPRINKLES THROUGH THE REST OF THE MORNING...AS SOME ISOLATED VERY
LIGHT SHOWERS CONTINUE TO DEVELOP OVER THE AREA IN ASSOCIATION
WITH STRONG WARM AIR ADVECTION. THIS ACTIVITY SHOULD SHIFT EAST OF
THE AREA THIS AFTERNOON...WITH TEMPERATURES STILL EXPECTED TO TOP
OUT AROUND 80 IN THE CHICAGO AREA...AND INTO THE LOWER 80S OUT BY
ROCKFORD. WHILE THERE REMAINS A SMALL CHANCE THAT A LAKE BREEZE
COULD DEVELOP THIS AFTERNOON ALONG THE LAKE SHORE...IT APPEARS THE
WEST-SOUTHWEST WINDS COULD BE JUST STRONG ENOUGH TO KEEP IT FROM
SHIFTING VERY FAR INLAND. AS A RESULT...THERE MAY NOT BE MUCH LAKE
COOLING ON THE LAKESHORE TODAY.

KJB

&&

.SHORT TERM...
327 AM CDT

THROUGH SATURDAY NIGHT...

MAIN FORECAST CONCERNS/CHALLENGES ARE WITH CLOUD COVER AND HIGH
TEMPS TODAY...INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS
SATURDAY...AND THEN WITH PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS NEXT WEEK.

RELATIVELY QUIET THIS MORNING WITH SURFACE RIDGE AXIS SITUATED
ACROSS THE REGION/CWA. SKIES HAVE REMAINED CLEAR OVERNIGHT BUT
LOOKING UPSTREAM ACROSS WISCONSIN...CAN SEE AN EXPANDING AREA OF
MID LEVEL CLOUDS RAPIDLY PUSHING SOUTH INTO THE CWA. SOUTHWARD
DROPPING SPEED MAX AND STRONG WAA LIKELY OWING FOR THIS EXPANSION
AND DONT SEE WHY THIS WILL DIMINISH AS IT PUSHES THROUGH THE CWA.
SO HAVE INCREASED CLOUD COVER THIS MORNING BUT MAY NEED TO DO SOME
LAST MINUTE ADJUSTMENTS TO FURTHER INCREASE...WITH A PERIOD OF AT
LEAST PARTLY SUNNY SKIES LIKELY THIS MORNING FOR MOST AREAS IN
NORTHERN ILLINOIS AND NORTHWEST INDIANA. CAN SEE A STEADILY MOVING
BACK EDGE TO THIS MID LEVEL MOISTURE WHICH IS CONSISTENT WITH
SHORT TERM GUIDANCE INDICATING THIS WILL EXIT TO THE
SOUTH/SOUTHEAST BY AROUND MIDDAY...WITH SUNNY TO PARTLY CLOUDY
SKIES THEN LIKELY IN THE AFTERNOON. ALSO UP NORTH ARE SOME WEAK
RETURNS ON RADAR AT THIS TIME BUT DONT THINK THIS IS REALLY
REACHING THE GROUND. HAVE MAINTAINED A DRY FORECAST THIS MORNING
BUT AN ISOLATED SPRINKLE COULD BE POSSIBLE. WARMER TEMPS STILL
EXPECTED TODAY DESPITE THIS CLOUD COVER. ALTHOUGH IT MAY INITIALLY
HINDER TEMP TRENDS IN THE MORNING...THE STRONG WAA WILL USHER IN A
MUCH WARMER AIRMASS THAT WILL STILL ALLOW TEMPS TO RISE TO THE 80S
IN NORTHERN ILLINOIS AND MID TO UPPER 70S ACROSS NORTHWEST
INDIANA. WITH SURFACE RIDGE AXIS AND LIGHTER FLOW AROUND...AM A
LITTLE CONCERNED FOR A PERIOD OF ONSHORE FLOW TODAY AND DID LOWER
TEMPS NEAR THE LAKE. HAVE MORE LOW TO MID 70S FOR AREAS NEAR THE
LAKE.

AS ONE UPPER LEVEL LOW/TROUGH EXITS TO THE EAST...ANOTHER UPPER
LEVEL SYSTEM WILL DROP SOUTH INTO THE UPPER MIDWEST AND GREAT
LAKES REGION TONIGHT INTO SATURDAY. THIS WILL ALLOW SURFACE LOW
AND FRONTAL BOUNDARY TO DROP SOUTH THROUGH WISCONSIN TONIGHT AND
AS THIS OCCURS...UPSTREAM MOISTURE/INSTABILITY AXIS WILL SWING
THROUGH. GUIDANCE FAIRLY CONSISTENT WITH THIS AND EXPECT
INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS EARLY SATURDAY
MORNING. HAVE INCREASED POPS DURING THIS TIME BUT KEPT AT HIGH
CHANCE OWING TO LOWER CONFIDENCE ON COVERAGE. HOWEVER...ITS
APPEARING THAT MOST LOCATIONS WILL OBSERVE AT LEAST A SMALL WINDOW
OF PRECIP SATURDAY MORNING. THUNDER DOES APPEAR POSSIBLE SATURDAY
MORNING BUT AM NOT ANTICIPATING ANYTHING SEVERE DURING THAT TIME.
AM MONITORING THE SATURDAY AFTERNOON PERIOD FOR POSSIBLE
ADDITIONAL THUNDERSTORM DEVELOPMENT...SOME OF WHICH COULD BE
STRONG. ALTHOUGH THE SIGNAL FOR STRONG THUNDERSTORMS APPEARS TO BE
HIGHER FURTHER TO THE SOUTH OF THE CWA...MOISTURE POOLING AHEAD OF
THIS FRONT AND INCREASING INSTABILITY AHEAD OF APPROACHING SPEED
MAX COULD ALLOW FOR SOME ISOLATED STRONG STORMS SOUTH OF A PONTIAC
IL TO FOWLER INDIANA LINE. THIS POTENTIAL SHOULD QUICKLY END BY
THE EARLY EVENING WITH THE ARRIVAL OF DRIER AIR...BUT WITH SHOWERS
STILL POSSIBLE FOR AREAS OVER THE FAR SOUTHERN CWA.

RODRIGUEZ

&&

.LONG TERM...
327 AM CDT

SUNDAY THROUGH FRIDAY...

THE END OF THE WEEKEND WILL BE DRY BUT AN ACTIVE PATTERN WILL
REMAIN IN PLACE OVER THE CONUS. GUIDANCE SHOWING ANOTHER LARGE
UPPER LEVEL SYSTEM WORKING ITS WAY TOWARD THE REGION SUNDAY NIGHT
INTO MONDAY WITH SHOWERS AND THUNDERSTORMS INCREASING ONCE AGAIN
LATE IN THE NIGHT INTO MONDAY MORNING. LOW CONFIDENCE WITH EXACTLY
HOW MONDAY WILL EVOLVE GIVEN ANTICIPATED ONGOING
SHOWER/THUNDERSTORM ACTIVITY BUT GIVEN INCREASING
MOISTURE/INSTABILITY BEHIND LIFTING FRONTAL BOUNDARY AND
PERSISTENT FORCING ALOFT...WILL NEED TO MONITOR ANOTHER PERIOD FOR
POSSIBLE STRONG THUNDERSTORMS SOMEWHERE ACROSS THE REGION. GIVEN
THE ANTICIPATED CLOSED NATURE OF THIS NEXT SYSTEM AM NOT OVERLY
CONFIDENT WITH MODEL SOLUTIONS AT THIS TIME. NONETHELESS...AN
ACTIVE PERIOD IS APPEARING PROBABLY EARLY NEXT WEEK WITH THIS
SYSTEM LIKELY TO LINGER AROUND THE CWA ON TUESDAY AS WELL. IF THIS
WERE TO OCCUR...THUNDERSTORM DEVELOPMENT WILL AGAIN BE POSSIBLE.

RODRIGUEZ

&&

.AVIATION...
FOR THE 12Z TAFS...

HIGH PRESSURE REMAINS OVERHEAD...HOWEVER A WEAK MID-LEVEL SYSTEM
WAS SLIDING SOUTH AND PRODUCING SOME SPRINKLES AND CLOUDS AROUND
8-12KFT AGL. BASED ON LATEST GUIDANCE SPRINKLES SHOULD ONLY LAST
THROUGH ABOUT 15Z AND REMAIN VERY MINIMAL IN COVERAGE. WINDS WILL
START OUT FROM THE WEST WITH SPEEDS AROUND 5 TO 7KT...THEN AS THE
DAY PROGRESSES WINDS SHOULD INCREASE SLIGHTLY AND TURN
SOUTHWESTERLY. WINDS ALOFT SHOULD REMAIN STRONG ENOUGH FROM THE
SOUTHWEST TO PREVENT A LAKE BREEZE FROM MOVING INLAND...SO HAVE
HELD ONTO THE SOUTHWEST WINDS THROUGH THIS AFTERNOON. HIGH
PRESSURE WILL STEADILY DRIFT SOUTH AS A FRONTAL BOUNDARY BEGINS TO
SLIDE SOUTH ACROSS NORTHERN WISCONSIN LATE TONIGHT. THIS FRONTAL
BOUNDARY WILL LIKELY NOT ARRIVE ACROSS NORTHERN ILLINOIS UNTIL
CLOSER TO DAYBREAK WITH WINDS BEGINNING TO TURN NORTHWESTERLY AND
EVENTUALLY NORTH...ALONG WITH INCREASING IN SPEEDS. THERE WILL BE
A CHANCE FOR A FEW THUNDERSTORMS SHORTLY AFTER DAYBREAK
SATURDAY.

BEACHLER

&&

.MARINE...
258 AM CDT

HIGH PRESSURE CONTINUES TO BE IN CONTROL OF MUCH OF THE GREAT
LAKES REGION TODAY...STRETCHING SOUTH THROUGH THE GULF OF MEXICO.
HOWEVER THIS RIDGE OF HIGH PRESSURE WILL STEADILY DRIFT SOUTH
WHILE A LOW PRESSURE WILL SLIDE EAST ACROSS WESTERN ONTARIO
TOWARDS QUEBEC BY EARLY SATURDAY. THIS WILL PRODUCE A TRAILING
FRONTAL BOUNDARY THAT WILL SAG SOUTH ACROSS LAKE MICHIGAN EARLY
SATURDAY FOR THE NORTHERN HALF OF THE LAKE...THEN STEADILY PUSH
SOUTH TO THE SOUTHERN HALF OF LAKE MICHIGAN. WINDS WILL REMAIN
RELATIVELY LIGHT THIS MORNING...BUT INCREASE THROUGHOUT THE
AFTERNOON FROM THE SOUTH/SOUTHEAST TO 15 TO 25 KT. THIS WILL
RESULT IN WAVES BUILDING ALONG THE NORTHERN HALF OF LAKE
MICHIGAN...HOWEVER WITH THE MUCH WARMER AIR FLOWING OVER THE LAKE
WAVES WILL LIKELY NOT BUILD MUCH BEYOND 3 TO 5 FT.

THE WEAK GRADIENT MAY TURN WINDS SOUTHEASTERLY WITHIN THE ILLINOIS
NEARSHORE WATERS THIS AFTERNOON...BUT THEN AS THE FRONTAL BOUNDARY
SAGS SOUTH OVERNIGHT/EARLY SATURDAY...WINDS WILL INCREASE FROM THE
SOUTH AND THEN BEHIND THE FRONT QUICKLY TURN NORTHWESTERLY TO
NORTHERLY. WAVES WILL BE INCREASING SATURDAY FOR THE SOUTHERN HALF
OF THE LAKE...AND COULD COME CLOSE TO SMALL CRAFT HAZARDS FOR THE
INDIANA NEARSHORE WATERS. WINDS WILL THEN BEGIN TO DIMINISH LATER
SATURDAY EVENING...THEN TURN EASTERLY.

BEACHLER

&&

.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.