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Weather Story NWS Chicago, IL |
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Cloudy skies will make way for sunny conditions today as a slow moving upper level system to the east continues to pull away. With these clearing skies, temperatures will be able to rise to the 50s today. Clear skies will continue tonight before cloud cover increases once again on Tuesday as an upper level disturbance drops south into the region. As this passes through, a slight chance for showers will be possible Tuesday night, mainly across portions of west central Illinois.
000 FXUS63 KLOT 151111 AFDLOT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 611 AM CDT MON MAR 15 2010 .DISCUSSION... 401 AM CDT AS WAS EXPECTED THIS PAST EVENING...THERE WERE SOME LINGERING SCATTERED LIGHT RAIN SHOWERS OR SPRINKLES WHICH MOVED ACROSS THE EASTERN TWO THIRDS OF THE CWA. THIS HAS SINCE ENDED WITH LATEST RADAR TRENDS UPSTREAM SHOWING THIS MOISTURE DISSIPATING WITH ITS WESTWARD PROGRESSION. EVEN WITH EXTENSIVE CLOUD COVER WRAPPING CYCLONICALLY THROUGH THE CWA...DONT ANTICIPATE ANY MORE SPRINKLES TO BE OBSERVED THIS MORNING WITH LATEST SATELLITE IMAGERY INDICATING DRIER AIR TRYING TO MAKE ITS WAY INTO THE REGION. TURNING TO CLOUD COVER...MOST OF THE CWA IS STILL OVERCAST THIS MORNING WITH A FAIR AMOUNT OF EROSION OCCURRING OVER THE LAST SEVERAL HOURS OVER PORTIONS OF WISCONSIN...EASTERN IOWA AND NORTHWEST ILLINOIS. THIS IS ASSOCIATED WITH LARGE SCALE SUBSIDENCE AND HEIGHT RISES ALOFT ACROSS MUCH OF THE UPPER MIDWEST. AS THIS UPPER LEVEL RIDGE TRIES TO BUILD EAST ACROSS THE FA TODAY...IT WILL BE RUNNING INTO THE STUBBORN UPPER LEVEL SYSTEM TO THE EAST. THIS WILL HELP TO SLOW DOWN THE PROCESS OF FURTHER EROSION OF THIS CLOUD DECK SOUTHEAST ACROSS THE REST OF THE CWA. ALTHOUGH IT WILL BE SLOW...SKIES WILL CONTINUE TO SCATTER OUT BY THIS AFTERNOON WITH SKIES BECOMING MOSTLY CLEAR BY TONIGHT. WORTHY TO NOTE IS THE EXTENSIVE CLOUD DECK STRETCHED ACROSS MUCH OF THE CENTRAL PLAINS THIS MORNING. WATER VAPOR IMAGERY SHOWS A COUPLE SMALLER SCALE VORTICITY MAXIMUM SLOWLY MOVING THROUGH THE CENTRAL PLAINS. FOR THE TIME BEING...EXPECT THIS CLOUD COVER TO REMAIN TO THE WEST. WITH NO REAL STEERING FLOW ALOFT...THESE WEAKENING IMPULSES WILL REMAIN IN THE CENTRAL PLAINS...FOR THE TIME BEING. HAVE BUMPED UP HIGH TEMPS TO THE MID AND UPPER 50S ACROSS THE FA FOR TODAY...WITH HIGHEST TEMPS BEING OBSERVED IN THE WESTERN HALF OF THE CWA WITH MORE OF THE DAY BEING SPENT ABSORBING SOLAR INSOLATION RATHER THAN SPENT UNDER CLOUD COVER. AFTER CLEAR SKIES TONIGHT...CLOUD COVER WILL BEGIN TO INCREASE FROM THE NORTHWEST ON TUESDAY AS PREVIOUSLY MENTIONED WEAK IMPULSES PHASE INTO A SHORT WAVE TROUGH DROPPING SOUTH OUT OF CANADA. CURRENTLY THINK THAT THIS CLOUD COVER WILL NOT MAKE MUCH PROGRESS EAST INTO THE ENTIRE CWA...SO THE EASTERN PART OF THE CWA COULD OBSERVE ANOTHER SUNNY DAY WITH FORECAST HIGH TEMPS IN THE UPPER 50S ON TUESDAY. DONT ANTICIPATE MUCH IN TERMS OF PRECIPITATION...ONLY FORECASTING SLIGHT CHANCE POPS TUESDAY NIGHT FOR OUR FAR WESTERN PART OF THE CWA AS TROUGH AND BETTER FORCING STAY OFF TO THE WEST. ONCE THIS WAVE DROPS SOUTH OUT OF THE AREA EARLY WEDNESDAY...UPPER LEVEL RIDGE BUILDS BACK INTO THE REGION. SKIES CLEAR WITH TEMPS ALSO WARMING ONCE AGAIN ON WEDNESDAY. AT THE SURFACE...RIDGE OF HIGH PRESSURE DROPS SOUTH INTO THE SOUTHERN PLAINS. WINDS WILL BEGIN TO BACK TO THE WEST...AND START A TREND OF WAA INTO THE CWA PAVING THE WAY FOR A BEAUTIFUL THURSDAY. RODRIGUEZ && .AVIATION... 1200 UTC TAFS...NORTHWEST FRINGES OF STRATUS DECK FROM MASSIVE STORM TO THE EAST CONTINUES TO BLANKET MUCH OF THE AREA WITH CIGS DANCING RIGHT AROUND THE VFR/MVFR THRESHOLD. WRF-NAM AND TO LESSER EXTENT GFS SHOW A TROUGH AT 925MB ROTATING THROUGH THE AREA EARLY THIS AFTERNOON WITH A RESULTANT INCREASE IN LOWER LEVEL RH...SO HAVE OPTED TO HANG ONTO MVFR CIGS A BIT LONGER THAN TYPICAL DIURNAL TRENDS WOULD ARGUE FOR. SHOULD FINALLY SEE THIS CLOUD DECK MOVE OUT FROM NW TO SE LATE THIS AFTERNOON/EARLY THIS EVENING WITH CLEARING SKIES AND DIMINISHING WINDS TONIGHT. WET/COLD GROUND AND NEARLY IDEAL RADIATIONAL COOLING WILL LIKELY RESULT IN SOME LIGHT FOG DEVELOPING TONIGHT AWAY FROM URBAN HEAT AT DPA/RFD. MAV AND MET BOTH SUGGEST GREATER THAN 60 PERCENT PROBABILITIES OF VSBYS FALLING TO IFR OR LOWER...THOUGH MOS VSBY CAT WITH SINGLE HIGHEST PROB IS MVFR. HAVE INTRODUCED MVFR VSBYS FOR NOW AND WILL ALLOW LATER SHIFTS PONDER BRINGING VSBYS LOWER. IZZI && .MARINE... 255 AM CDT NORTHERLY WINDS HAVE BEGUN TO SUBSIDE AND THIS TREND WILL CONTINUE TODAY/TONIGHT AS EAST COAST LOW PULLS OUT TO SEA. A LARGE RIDGE OF HIGH PRESSURE WILL BEGIN TO BULGE EASTWARD INTO THE GREAT LAKES BY TUESDAY AND WEDNESDAY. AS THIS OCCURS THE PRESSURE GRADIENT WILL GO LIMP AND ALLOW FOR DIURNAL LAND-SEA BREEZE CYCLE TO DOMINATE WINDS OVER THE LAKE. RIDGE WILL SAG SOUTHWARD LATER IN THE WEEK ALLOWING FOR A MORE ROBUST...THOUGH STILL NOT PARTICULARLY STRONG...SOUTHWESTERLY WIND TO DEVELOP OVER THE LAKE BY THURSDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$