Area Forecast Discussion
Issued by NWS Chicago, IL

Home | Current Version | Previous Version | Text Only | 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 061747
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1147 AM CST SAT FEB 6 2016

.UPDATE...
932 AM CST

FOR MORNING UPDATE...

AFTER MOSTLY CLEAR SKIES EARLY THIS MORNING ACROSS MUCH OF THE
FORECAST AREA...AN AREA OF STRATUS WAS SPREADING ACROSS NORTHERN
IL ESPECIALLY NORTH OF THE I-88 CORRIDOR AND WILL MAKE FOR CLOUDY
OR MOSTLY CLOUDY SKIES FOR THESE LOCATIONS TODAY. GUIDANCE
SUGGESTS EXTENSIVE AREA OF LOWER CLOUDS WITHIN WEAK LOW LEVEL
MOIST AXIS OVER IA WILL CONTINUE TO MOVE SLOWLY EASTWARD AND
AFFECT MAINLY NORTHERN HALF OR SO OF THE CWA. RELATIVELY SHALLOW
NATURE OF CLOUD DECK AS INFERRED FROM VISIBLE SATELLITE IMAGERY
AND RAP SOUNDINGS...COMBINED WITH PASSAGE OF MID-LEVEL SHORT WAVE
TROUGH SHOULD PRECLUDE ANY PRECIPITATION AND HAVE REMOVED FLURRIES
FROM MORNING FORECAST. HAVE ALSO DECREASED CLOUD COVER ACROSS
SOUTHERN COUNTIES OF THE CWA THROUGH MUCH OF THE AFTERNOON. OTHER
ELEMENTS OF THE FORECAST...INCLUDING TEMPERATURES...APPEAR TO BE
ON TRACK. UPDATED GRIDS/ZFP AVAILABLE.

RATZER

&&

.SHORT TERM...
327 AM CST

THROUGH SUNDAY...

AN UPPER LEVEL TROUGH AND VORT STREAMER SLIDE SOUTHEAST THROUGH THE
REGION THIS MORNING WITH SCATTERED FLURRIES ALSO SHIFTING SOUTHEAST.
THE FLURRIES ARE STRUGGLING RIGHT NOW...AND NOT EXPECTING ANY
ACCUMULATION.  SOUTHWEST WINDS USHER IN WARMER AIR WITH HIGHS AROUND
40. LOCATIONS SOUTH OF I-80 SHOULD SEE SOME SUN TODAY...AND THE SUN
SHOULD HELP TEMPS RISE INTO THE LOW TO MID 40S.

THE NEXT SYSTEM MOVES OVER NORTHERN WISCONSIN BY LATE SUNDAY
AFTERNOON.  THE VORT STREAMER ASSOCIATED WITH THE UPPER LEVEL LOW
MOVES OVER NW IL SUNDAY AFTERNOON AND COULD KICK OFF LIGHT RAIN
SUNDAY AFTERNOON.  THE GFS IS MORE BULLISH THAN THE OTHER MODELS
REGARDING PRECIP SUNDAY...SO ONLY HAVE A SLIGHT CHANCE OF RAIN.
CONFIDENCE IS LOW IN THE OCCURRENCE AND EXTENT OF RAIN SUNDAY
AFTERNOON...BUT HAVE HIGH CONFIDENCE THAT ANY PRECIP THAT FALLS WILL
BE RAIN. HIGH TEMPS SUNDAY WILL BE IN THE LOW TO MID 40S.

JEE

&&

.LONG TERM...
327 AM CST

SUNDAY NIGHT THROUGH SATURDAY...

THE UPPER LEVEL TROUGH TAKES IT TIME SHIFTING EAST THROUGH MID TO
LATE NEXT WEEK.  THE SURFACE LOW ALSO HANGS AROUND THE GREAT LAKES
THROUGH MID WEEK.  THE UPPER LEVEL VORT STREAMERS ASSOCIATED WITH
THE TROUGH WILL FORCE PRECIP THROUGH TUESDAY EVENING...AND LAKE
EFFECT SNOW WILL LINGER THROUGH WEDNESDAY FOR NW INDIANA.  RAIN WILL
TURN TO SNOW SUNDAY NIGHT AND THEN LIGHT SNOW WILL FALL MONDAY
THROUGH TUESDAY NIGHT. FORECAST SOUNDINGS FEATURE WEAK FORCING...BUT
A DEEP DGZ. SO EXPECTING A LIGHT PERSISTENT SNOWFALL THAT GRADUALLY
ACCUMULATES. THE TYPE OF SNOW SHOULD START AS A WET SNOW BUT QUICKLY
TRANSITION TO A DRY SNOW.  PRELIMINARY EVENT TOTALS ARE ONLY 1-2
INCHES WITH HIGHER AMOUNTS ACROSS PORTER COUNTY WHERE LAKE EFFECT
SNOW WILL LINGER LONGER.  BREEZY NORTHWEST WINDS COULD RESULT IN
AREAS OF BLOWING SNOW MONDAY NIGHT AND TUESDAY ESPECIALLY IN OPEN
AREAS.

TEMPS FALL THROUGH WEDNESDAY AS COLD AIR ASSOCIATED WITH THE TROUGH
SPREADS OVER THE REGION. HIGH TEMPS WEDNESDAY WILL BE AROUND 20. THE
COLDEST NIGHT WILL BE TUESDAY NIGHT WITH TEMPS RANGING FROM +5 TO
+12...BUT WIND CHILLS WILL BE 5 TO 10 BELOW ZERO.

THE ECMWF FEATURES AN UPPER LEVEL WAVE BRINGING PRECIP TO THE REGION
WEDNESDAY AFTN WHILE THE GFS HAS THE WAVE FIZZLING OUT. KEPT THE
FORECAST DRY DUE TO A LACK OF CONFIDENCE...BUT THE MODELS SHOW A
LITTLE BETTER AGREEMENT ON A SLIGHT CHANCE OF PRECIP FRIDAY.
SLIGHTLY BELOW NORMAL TEMPS CONTINUE THROUGH LATE NEXT WEEK.

JEE

&&

.AVIATION...
FOR THE 18Z TAFS...

MAIN AVIATION CONCERNS ARE A SHORT DURATION OF MVFR CIGS EARLY
THIS AFTERNOON...AND POTENTIAL FOR GUSTY WEST-SOUTHWEST ON SUNDAY.

WEAK SURFACE TROUGH WAS ALONG THE MISSISSIPPI RIVER AT MIDDAY.
SOUTHWEST FLOW ABOVE THE SURFACE WAS HELPING TO ADVECT AN AREA OF
LOW LEVEL MOISTURE AND MVFR CEILINGS ACROSS FAR NORTHERN IL...WITH
NORTHERN IL TERMINAL SITES GENERALLY ALONG THE SOUTHERN PERIPHERY
OF THE MORE SOLID CLOUD COVER. BASED ON VISIBLE SATELLITE TRENDS...
A BRIEF 1-3 HOUR PERIOD OF MVFR CIGS IN THE 1500-2000 FT RANGE
WILL LIKELY AFFECT ORD/DPA/MDW/RFD...WITH GYY EXPECTED TO REMAIN
SCATTERED AT BEST. RFD WILL BE CLOSER TO THE MORE WIDESPREAD CLOUD
COVER TO THE NORTH AND WEST THOUGH IT APPEARS THAT RFD WILL ALSO
SCATTER OUT. WINDS THEN LOOK TO BACK SLIGHTLY MORE SOUTH-SOUTHWEST
THIS EVENING...IN RESPONSE TO SURFACE PRESSURE FALLS ASSOCIATED
WITH LOW PRESSURE MOVING SOUTHEAST INTO THE NORTHERN PLAINS.
EXTENSIVE AREA OF IFR/LIFR OVER IA EXPECTED TO LIFT MORE NORTHEAST
THAN EAST OVERNIGHT...WITH GUIDANCE KEEPING IL/NW IN TERMINALS
VFR WHILE ERODING AND SHIFTING IFR CIGS NORTHEAST ACROSS WI.

AFOREMENTIONED LOW PRESSURE TRACKS ACROSS THE NORTHERN GREAT LAKES
REGION THROUGH SUNDAY...WITH A GRADUAL TIGHTENING OF THE GRADIENT
AND INCREASING SOUTH-SOUTHWEST WINDS OVERNIGHT. STRONG LOW LEVEL
INVERSION IS EXPECTED TO LIMIT GUSTINESS LATE TONIGHT...THOUGH
WINDS LIKELY GUSTING 20+ KTS FROM THE WEST-SOUTHWEST SUNDAY AS
PACIFIC COLD FRONT MOVES ACROSS THE REGION TRAILING THE LOW.
FORECAST SOUNDINGS FROM VARIOUS MODELS MAINTAIN CONSIDERABLE DRY
AIR IN THE LOW-MID LEVELS WITH VFR CONDITIONS EXPECTED AND MINIMAL
PRECIP THREAT.

RATZER

&&

.MARINE...
119 AM CST

A WEAK BUT DEEPENING LOW PRESSURE JUST NORTH OF LAKE SUPERIOR EARLY
THIS MORNING WILL QUICKLY SCOOT EAST THROUGH TODAY. MORNING WIND
GUSTS ACROSS THE NORTHERN THIRD TO HALF OF THE LAKE SHOULD BE AROUND
30 KT ASSOCIATED WITH THIS. SOUTHWEST WINDS WILL RE-INCREASE TO THAT
MAGNITUDE TONIGHT AS DEEP LOW PRESSURE BEGINS TO APPROACH FROM THE
SOUTHERN CANADIAN PROVINCES. THE WINDS ACTUALLY WILL EASE A TAD
SUNDAY AFTERNOON AND MORE SO SUNDAY NIGHT AS THE WARM ADVECTION
AHEAD OF THIS LOW WILL NOT BE PARTICULARLY STRONG.

HIGH UNCERTAINTY EXISTS ON HOW FAST THIS NEXT LOW WILL MOVE INTO
LOWER MICHIGAN ON MONDAY AFTERNOON OR EVENING. BEHIND IT THE
PRESSURE GRADIENT AND COLD ADVECTION MAY BE ENOUGH FOR AT LEAST
OCCASIONAL GALES MONDAY NIGHT INTO TUESDAY AND TUESDAY
NIGHT...ALTHOUGH THAT SIGNAL IS A BIT LESS THAN IT WAS 24 HOURS
AGO...LIKELY BECAUSE THE LOW HAS SLOWED IN MODEL GUIDANCE. THERE
MAY BE SOME LIGHT FREEZING SPRAY TUESDAY NIGHT AS A SECOND COLD
PUSH MOVES OVER THE LAKE...MAINLY OVER NORTHERN AND EASTERN
PORTIONS.

MTF

&&

.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.