Area Forecast Discussion
Issued by NWS Chicago, IL

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000 FXUS63 KLOT 270848 AFDLOT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 348 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 09Z... * NORTHEAST WINDS WITH GUSTS OF 15 TO 20 KT MONDAY AFTERNOON. KJB //DISCUSSION...UPDATED 06Z... THE REGION WILL AGAIN 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 MONDAY NIGHT 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 09Z... * HIGH FOR ALL ELEMENTS. KJB //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY THROUGH THURSDAY. PRIMARILY VFR. NORTH-NORTHEAST WINDS. FRIDAY...VFR. CHANCE OF SHOWERS FRIDAY NIGHT. SOUTHWEST WINDS BECOMING EAST IN THE AFTERNOON. SATURDAY...VFR. SOUTHWEST WINDS BECOMING SOUTHEAST IN THE AFTERNOON. RATZER && .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. && $$ 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

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