Area Forecast Discussion
Issued by NWS Chicago, IL

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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS63 KLOT 150858 AFDLOT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 358 AM CDT MON SEP 15 2014 .DISCUSSION... 311 AM CDT DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY SPECTACULAR WEATHER THE REMAINDER OF THE WEEK. FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY LOSE A LITTLE GROUND THIS AFTERNOON. STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN GRIDS. TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN THE COMING DAYS. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * COLD FRONT MIDDAY MONDAY BRINGING A WIND SHIFT TO THE NW OR NNE ALONG WITH MVFR POSSIBLY BRIEFLY IFR CONDITIONS AND RAIN. BMD //DISCUSSION...UPDATED 06Z... OVERNIGHT THROUGH AROUND MID MORNING MONDAY EXPECT STEADY STATE CONDITIONS WITH VERY LIGHT SSW FLOW AND VFR CONDITIONS. AN UPPER LEVEL WAVE WILL MOVE ACROSS THE REGION MONDAY BRINGING SHOWERS TO THE AREA BY LATE MORNING OR EARLY AFTERNOON. CIGS ARE EXPECTED TO LOWER TO AT LEAST MVFR AND SOME MODELS SUGGEST THE POSSIBILITY OF A COUPLE HOURS OF IFR CIGS AS THE SURFACE TROUGH DROPS ACROSS THE AREA. CIGS ARE EXPECTED TO QUICKLY SCATTER OUT THOUGH EARLY TO MID EVENING BEHIND THE FRONT. WINDS WILL BE TRICKY DURING THE DAY MONDAY. WINDS ARE EXPECTED TO SHIFT TO SOME SORT OF NORTHERLY COMPONENT BUT NOT QUITE SURE AT THIS POINT IF IT WILL BE NW OR NNE AT THE CHICAGO TERMINALS WHERE SOME GUIDANCE SHOWS THE FRONT SURGING AHEAD AND TURNING WINDS NNE OFF OF LAKE MICHIGAN. GIVEN THE RELATIVE WARMTH OF THE LAKE RELATIVE TO THE AIRMASS...WILL LEAN AWAY FROM THIS SOLUTION IN THE MEANTIME...BUT IF WINDS DO END UP TURNING MORE NNE IT WOULD LIKELY BE DURING THE AFTERNOON...THEN WINDS SHOULD EVENTUALLY SETTLE BACK TOWARDS THE NW LATER IN THE EVENING. BMD //ORD AND MDW CONFIDENCE...UPDATED 09Z... * LOW CONFIDENCE IN WIND DIRECTION POST FRONTAL MONDAY AFTERNOON. GUIDANCE RANGES FROM NW TO NNE. * MEDIUM CONFIDENCE IN MVFR CONDITIONS AND RAIN...LOW CONFIDENCE IN IFR. BMD //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY...VFR. NORTHWEST WINDS BECOMING WEST. WEDNESDAY...VFR. WEST WINDS BECOMING NORTHEAST. THURSDAY...VFR. EAST WINDS. FRIDAY...VFR. SOUTHEAST WINDS. SATURDAY...VFR. BREEZY SOUTH-SOUTHWEST WINDS. CHANCE OF THUNDERSTORMS. MDB && .MARINE... 303 AM CDT LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE AGAIN. BMD && .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/US.NATIONALWEATHERSERVICE.CHICAGO.GOV 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.