837 PM CDT
FOR EVENING UPDATE...
NO SIGNIFICANT CHANGES TO GOING FORECAST. ONLY MODS MADE TO GRIDDED
HOURLY TEMPS ETC...BASED ON EARLY EVENING OBS TRENDS. REMAINDER OF
FORECAST IS HARD TO IMPROVE UPON WITH HIGH PRESSURE IN CONTROL AND
SUPPLYING CLEAR SKIES...LIGHT WINDS AND MILD TEMPS. GOOD RADIATIONAL
COOLING CONDITIONS MAY AGAIN RESULT IN PATCHY FOG DEVELOPMENT AGAIN
LATE TONIGHT...PARTICULARLY SOUTHEASTERN CWA WHERE PRESSURE GRADIENT
IS WEAKEST. 00Z SOUNDINGS FROM ILX/DVN DEPICT VERY DRY LOW LEVEL
THERMODYNAMIC PROFILES...THOUGH THEY DID LAST NIGHT AS WELL AND SOME
SERIOUS FOG DEVELOPED. SLIGHTLY MORE SOUTH FLOW JUST ABOVE THE
BOUNDARY LAYER AS NOTED IN 925 HPA PROFILER WINDS AS COMPARED TO
LAST NIGHT MAY HELP TO KEEP FOG LESS WIDESPREAD...THOUGH WILL
HAVE TO MONITOR TRENDS OVERNIGHT.
RATZER
//PREV DISCUSSION...
326 PM CDT
FORECAST REMAINS ON TRACK WITH HIGH PRESSURE DOMINATING THROUGH THE
FORECAST PERIOD. AFTERNOON WATER VAPOR IMAGERY SHOWS OMEGA BLOCK IN
THE UPPER FLOW BECOMING BETTER ORGANIZED WITH A DEEP CLOSED LOW
SLOWLY MOVING NORTHEASTWARD UP THE NEW ENGLAND COAST...AN AMPLIFYING
RIDGE OVER THE CENTRAL CONUS AND A LONGWAVE TROUGH OVER THE WEST
COAST. THIS TROUGH IS COMPRISED OF ONE CLOSED LOW OVER SOUTHERN
CALIFORNIA AND ANOTHER JUST WEST OF THE BRITISH COLUMBIA COAST. AT
THE SURFACE...EXPANSIVE HIGH PRESSURE WHICH WAS CENTERED OVER THE
AREA IS NOW SHIFTING EASTWARD ACROSS INDIANA AND INTO KENTUCKY. AS A
RESULT...QUIET AND MILD WEATHER CONTINUES.
TONIGHT THROUGH THURSDAY...DESPITE HIGH PRESSURE MOVING OFF TO THE
EAST WINDS REMAIN LIGHT AND VARIABLE ACROSS THE AREA WITH A LAKE
BREEZE PUSHING INLAND LATE THIS AFTERNOON. CLEAR SKIES CONTINUE AND
WILL CONTINUE INTO THE OVERNIGHT HOURS. WINDS WILL REMAIN LIGHT AND
VARIABLE AND CALM IN SPOTS OVERNIGHT AND COMBINE WITH THE CLEAR
SKIES TO ALLOW GOOD RADIATIONAL COOLING. WITH A WARMER AIRMASS IN
EXPECT THAT LOWS WILL BE WARMER THAN LAST NIGHT BUT COOLER THAN
GUIDANCE ONCE AGAIN FOR MOST OF THE MORE RURAL AREAS. MAY BE A FEW
DEGREES TOO WARM IN SOME SPOTS FROM DEKALB DOWN TO JOLIET AND
PONTIAC AND EASTWARD TOWARDS RENSSELAER INDIANA SO WILL NEED TO
MONITOR THROUGH THE EVENING. HAVE INCLUDED PATCHY FOG ACROSS MOST OF
THESE AREAS AS WELL. A STEADIER SOUTHERLY WIND WILL BE IN PLACE
WEDNESDAY ALLOWING HIGHS TO BE A COUPLE DEGREES WARMER UPPER 70S
ACROSS MOST OF THE AREA...WITH READINGS AROUND 80 SOUTH OF
INTERSTATE 80. A LAKE BREEZE MAY DEVELOP BUT THE WIND DIRECTION WILL
BE SOUTHEASTERLY SO TEMPS ALONG THE ILLINOIS SHORE WILL BE
COOLER...PROBABLY RIGHT AROUND 70. THERE WILL BE A LITTLE CHANGE IN
THE WEATHER FOR THURSDAY OTHER THAN THE POTENTIAL FOR SLIGHTLY
WARMER HIGHS.
MDB
FRIDAY THROUGH TUESDAY...
DRY...QUIET WEATHER WILL CONTINUE THROUGH THE EXTENDED. MAIN FOCUS
WILL BE THE WELL ABOVE NORMAL TEMPERATURES FRIDAY THROUGH TUESDAY.
DEEP H5 TROUGH OVER THE INTERIOR WESTERN CONUS WILL CONTINUE TO
AMPLIFY DOWNSTREAM H5 RIDGE OVER EASTERN HALF OF CONUS. SOME
UNCERTAINTY CREEPS UP IN GFS ENSEMBLES REGARDING OVERALL EVOLUTION
OF UPPER LEVEL PATTERN LATE WEEKEND EARLY NEXT WEEK...BUT THEME
APPEARS TO BE H5 RIDGE FINALLY GETS BROKEN DOWN INTO MORE ZONAL FLOW
BY EARLY NEXT WEEK...BUT THEN WE GET INTO DRY SOUTHWEST FLOW AT THE
UPPER LEVELS AS A RESULT. THIS WOULD SERVE TO PROLONG DRY PATTERN
THROUGH MONDAY AND POSSIBLY ALL THE WAY THROUGH TUESDAY. 12Z ECMWF
AND 12Z GFS IN DISAGREEMENT...WITH ECMWF BRINGING PRECIP TO AREA ON
TUESDAY. PREFER DRY GFS FOR REASONS ABOVE...SO KEPT THE ENTIRE
EXTENDED PERIOD DRY AS A RESULT.
REGARDING TEMPERATURES...925 MB TEMPERATURES SETTLE IN AROUND 20C ON
FRIDAY AND SATURDAY. WITH PERSISTENT SOUTHERLY FLOW...FULL SUNSHINE
AND MIXING UP TO ABOUT 900 MB EXPECTED...HIGHS IN THE UPPER 70S AND
LOWER 80S ARE EXPECTED ON FRIDAY. SATURDAY WILL BE OFF TO A WARMER
START THAN FRIDAY DUE TO OVERNIGHT LOWS A FEW DEGREES WARMER...SO
SATURDAY WILL LIKELY BE EVEN WARMER THAN FRIDAY...IN THE LOWER 80S
NORTH HALF OF CWA AND LOW TO MID 80S SOUTH HALF OF CWA. WENT WITH
THE HIGHEST ENSEMBLE GFS MOS GUIDANCE FOR HIGHS ON SATURDAY. HIGH
PRESSURE MAY TRY TO BUILD IN FROM THE NORTH ON SUNDAY AND KNOCK DOWN
TEMPERATURES A FEW DEGREES...BUT STILL WELL ABOVE NORMAL. NOT
MUCH CHANGE AT 925 MB ON MONDAY...SO HIGHS AGAIN IN THE UPPER 70S
AND LOWER 80S. SOME SLIGHT COOLING IS EXPECTED ON TUESDAY AS H925
TEMPS DROP A FEW DEGREES...BUT FORECAST HIGHS ARE STILL IN THE MID
70S...10 DEGREES ABOVE NORMAL FOR MID OCTOBER. OVERNIGHT LOWS IN
THE EXTENDED WILL BE QUITE MILD AS WELL...WARMEST IN THE CHICAGO
HEAT ISLAND.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* NONE
KJB
//DISCUSSION...UPDATED 06Z...
IT WILL BE ANOTHER QUIET WEATHER DAY WITH NO MAJOR WEATHER CONCERNS
EXPECTED. WINDS WILL START OFF CALM THIS MORNING. HOWEVER SOUTHERLY
FLOW WILL COMMENCE LATER THIS MORNING AS THE SURFACE HIGH CONTINUES
TO PUSH EAST ACROSS THE OHIO VALLEY. THEN...DURING THE AFTERNOON THE
FLOW LOOKS TO BACK TO THE EAST SOUTHEAST OFF THE LAKE ALONG THE BACK
SIDE OF THE SURFACE RIDGE OF HIGH PRESSURE ACROSS THE EASTERN GREAT
LAKES. HOWEVER...IN SPITE OF THIS WIND SHIFT...THE SPEEDS WILL
REMAIN UNDER 10 KT.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* HIGH FOR ALL FORECAST ELEMENTS
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY THROUGH MONDAY...VFR.
SHEA
&&
.MARINE...
242 AM CDT
LIGHT S TO SW WINDS WILL GRADUALLY BECOME SE AND INCREASE TODAY
AND TONIGHT WITH A LARGE RIDGE OF HIGH PRESSURE EXTENDING FROM
HUDSON BAY S TO THE GULF OF MEXICO CONTINUE TO SLOWLY DRIFT E.
S WINDS WILL CONTINUE TO INCREASE FRI AND FRI NIGHT AS A TROUGH
OF LOW PRESSURE OVER THE HIGH PLAINS FORMS A DEEPENING LOW AS IT
LIFTS NE FROM THE DAKOTAS TO NORTHERN MANITOBA. S TO SW WINDS WILL
SLOWLY DIMINISH SAT NIGHT AS THE LOW MOVES FURTHER NE TO OVER
HUDSON BAY.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
