Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 271112
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
612 AM CDT MON APR 27 2015

.SHORT TERM...
320 AM CDT

THROUGH TUESDAY...

QUIET WEATHER IS EXPECTED OVER MUCH OF THE UPCOMING WEEK. FOR
MONDAY AND TUESDAY...SURFACE HIGH PRESSURE WILL BE IN PLACE
ACROSS THE CANADIAN PRAIRIES AND UPPER MIDWEST. WEATHER TODAY WILL
BE ALMOST A CARBON COPY OF YESTERDAY OUTSIDE OF A FEW ADDITIONAL
CLOUDS. EXPECT A MODEST NORTH/NORTHEAST WIND TO KEEP CONDITIONS
COOL AROUND 50 ALONG THE LAKE FRONT...BUT EXPECT UPPER 50S TO
AROUND 60 INLAND. UPPER RIDGING WILL GRADUALLY BUILD ACROSS THE
GREAT LAKES WITH MID LEVEL TEMPS WARMING AS THE THERMAL TROUGH
GETS SHUNTED OFF TOWARDS THE EAST COAST. SURFACE WINDS WILL BE
LIGHTER ON TUESDAY BUT STILL EXPECT ONSHORE FLOW KEEPING TEMPS
LOWER ALONG THE LAKE FRONT. INLAND...EXPECT A 4-5 DEGREE WARMUP
WITH TEMPS IN THE LOW TO MID 60S.

BMD

&&

.LONG TERM...
320 AM CDT

WEDNESDAY THROUGH SUNDAY... TEMPERATURES WILL INCH A COUPLE
DEGREES WARMER ON WEDNESDAY AHEAD OF AN UPPER LEVEL DISTURBANCE
PROGGED TO DIVE INTO THE MIDWEST WEDNESDAY EVENING BRINGING AT
LEAST A GLANCING BLOW OF SLIGHTLY COOLER AIR. MODELS HAVE GONE
BACK AND FORTH ON CHANCES FOR SHOWERS WITH THIS SYSTEM. ECMWF IS
NOW DRY WHILE THE GFS PRODUCES SOME CONVECTIVE PRECIP ACROSS NORTH
CENTRAL IL. LOOKING AT SOUNDINGS THOUGH...WARM NOSE AROUND 700 MB
SHOULD CAP DEEP CONVECTION AND THE ARRIVAL OF THE COLDER AIR LOOKS
TO JUST MIX PEAK HEATING. SUPPOSE I CANT RULE OUT A FEW SPRINKLES
BUT GIVEN THE DRYNESS OF THE AIRMASS THE POSSIBILITY IS PRETTY
MINIMAL. MORE LIKELY WOULD EXPECT DEWPOINTS TO MIX DOWN FARTHER IN
THE AFTERNOON RESULTING IN HIGH BASED CU AND MAYBE VIRGA. AT ANY
RATE NOT WORTH MORE THAN A SILENT 10 POP. AFTER A SLIGHT STEP BACK
IN TEMPS THURSDAY WITH HIGHS IN THE LOW TO MID 60S...THE WARMING
TREND KICKS BACK INTO GEAR TO END THE WEEK AND HEAD INTO THE
WEEKEND WITH 70S SATURDAY AS THE SURFACE RIDGE MOVES TO OUR EAST
AND RETURN FLOW OVERSPREADS THE FORECAST AREA...AND THEN POSSIBLY
EVEN UPPER 70S SUNDAY. MODELS AGAIN TRY TO PRODUCE SOME CONVECTION
OVER THE WEEKEND THOUGH SYNOPTIC FORCING IS FAIRLY WEAK...MAINLY
SOME MODEST MID LEVEL WARM AIR ADVECTION. DETAILS ARE FUZZY THIS
FAR OUT GIVEN THE SUBTLETY OF THE FORCING.

BMD

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* NORTHEAST WINDS WITH GUSTS OF 15 TO 20 KT THIS AFTERNOON.

KJB

//DISCUSSION...UPDATED 12Z...

THE REGION WILL REMAIN WITHIN SOUTHERN PERIPHERY OF A SURFACE
HIGH PRESSURE RIDGE OVER UPPER MIDWEST TODAY. THIS WILL AGAIN
RESULT IN A NORTHEASTERLY WIND COMPONENT AROUND 10-15 KTS WITH
GUSTS POTENTIALLY AS HIGH AS 20 KT GUSTS THIS AFTERNOON. THE
SURFACE PRESSURE GRADIENT WILL WEAKEN TONIGHT ALLOWING WINDS TO
DIMINISH BELOW 10 KTS. ASIDE FROM A DECK OF SCT TO PERHAPS BRIEFLY
BKN CLOUD COVER AT OR JUST ABOVE 3,000 FEET AGL DURING THE DAY
TODAY...VFR CONDITIONS ARE EXPECTED DURING THE PERIOD.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

TUESDAY NIGHT THROUGH THURSDAY. PRIMARILY VFR. NORTH-NORTHEAST
WINDS.

FRIDAY...VFR. CHANCE OF SHOWERS FRIDAY NIGHT. SOUTHWEST WINDS.

SATURDAY...VFR. SOUTHWEST WINDS BECOMING EAST-SOUTHEAST IN THE
AFTERNOON.

SUNDAY...CHANCE OF TSRA. SOUTH WINDS.

KJB

&&

.MARINE...
219 AM CDT

NORTHERLY WINDS UP AROUND 20 KT WILL CONTINUE OVER TODAY...AND DUE
TO THE PROLONGED ONSHORE FLOW OVER THE PAST FEW DAYS OVER THE
ILLINOIS AND INDIANA NEAR SHORES...I HAVE DECIDED TO EXTEND THE
SMALL CRAFT ADVISORY THROUGH EARLY THIS EVENING. WAVES FROM THE
MICHIGAN CITY BUOY HAVE BEEN HOVERING RIGHT AROUND 4 FEET FOR THE
LAST SEVERAL HOURS...AND I DONT SEE ANY REASON WHY THESE WAVES WOULD
SUBSIDE MUCH GIVEN THE CONTINUED ONSHORE FLOW TODAY. THESE NORTHERLY
WINDS WILL EASE TONIGHT AS THE SURFACE RIDGE OF HIGH PRESSURE BEGINS
TO SHIFT OVER THE LAKE. THIS WILL SET UP LIGHTER ONSHORE LAKE BREEZE
INFLUENCED WINDS ON TUESDAY.

WIND SPEEDS COULD END UP INCREASING A BIT AGAIN OUT OF THE NORTH BY
LATE IN THE WEEK AS IT APPEARS THAT A LOW PRESSURE SYSTEM WILL OVER
THE NORTHEASTERN CONUS...AND THIS COULD SET UP ANOTHER ENHANCED
SURFACE GRADIENT SUPPORTIVE OF MODERATELY STRENGTH NORTHERLY WINDS
LATER WEDNESDAY AND THURSDAY. THIS COULD AGAIN CAUSE MY NEAR SHORE
WATERS TO FLIRT WITH SMALL CRAFT ADVISORY CRITERIA WAVES.

KJB

&&

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

&&

$$

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