332 AM CDT
THE MAIN FORECAST CONCERNS WILL BE THE POTENTIAL FOR FROST ACROSS
MY WESTERN AND SOUTHERN COUNTIES TONIGHT.
SURFACE HIGH PRESSURE CENTERED ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY THIS MORNING IS ALLOWING TEMPERATURES TO DROP NICELY THIS
MORNING ACROSS MY NORTH CENTRAL ILLINOIS COUNTIES. HOWEVER...A
PREVAILING LIGHT NORTHERLY WIND IS KEEPING TEMPERATURES FROM
DROPPING LOWER THEN THE MID TO UPPER 30S. I STILL ANTICIPATE THAT
NORTH CENTRAL ILLINOIS WILL SEE SOME SPOTTY FROST...ESPECIALLY IN
WELL PROTECTED AREAS.
THIS SURFACE HIGH WILL SLOWLY SHIFT SOUTHWARD ACROSS NORTHERN
ILLINOIS LATER TODAY. TEMPERATURES WILL BE UNSEASONABLY COOL UNDER
THIS HIGH TODAY WITH MID TO UPPER 50S LIKELY ACROSS THE REGION.
THESE COOL DAY TIME HIGHS WILL SET THE STAGE FOR LOW TO MID 30S
ACROSS ALL AREAS EXCEPT FOR CHICAGO AND AREAS NEAR THE LAKE TONIGHT
UNDER MOSTLY CLEAR SKIES AND LIGHT WINDS. I AM CONCERNED THAT SOME
AREAS ACROSS NORTH CENTRAL ILLINOIS WILL SEE TEMPERATURES DROP
BELOW 32 TONIGHT. I HAVE UNDERCUT GUIDANCE BY SEVERAL DEGREES
GIVEN THE PROXIMITY OF THE SURFACE HIGH AND THE ANTICIPATION OF
EFFICIENT RADIATIONAL COOLING. HOWEVER...I HAVE OPTED TO HOLD OFF
ON FROST HEADLINES IN ORDER TO LET THE DAY SHIFT GET A BETTER
UNDERSTANDING OF THE EXACT AREAS MOST AT RISK.
A GOOD WARMING TREND WILL BEGIN NEXT WEEK. HOWEVER...IT APPEARS THAT
THIS WARMING TREND MAY BE SOMEWHAT SLOWER THAN PREVIOUS ANTICIPATED.
HURRICANE OPHELIA WILL MOVE NORTH ACROSS THE ATLANTIC OVER THE NEXT
COUPLE OF DAYS AND THIS WILL TEMPORALLY HALT THE PROGRESS OF THE
EAST COAST LOW...AND ALSO THE SURFACE HIGH ACROSS OUR AREA. BECAUSE
OF THIS...TEMPERATURES MAY BE SLOW TO WARM ON SUNDAY IN SPITE OF
THE FACT THAT MID LEVEL TEMPERATURES WILL BE ON THE RISE.
TEMPERATURES MAY ONLY TOP OUT IN THE LOW TO MID 60S DUE TO WEAK
BOUNDARY LAYER WINDS AND POOR MIXING. BECAUSE OF THIS...THE REALLY
NICE TEMPERATURES IN THE 70S MAY NOT GET HERE UNTIL MONDAY.
THE UPPER LEVEL RIDGE WILL BUILD EASTWARD THROUGH MID WEEK...LIKELY
PRODUCING A FEW WARM AND DRY DAYS ACROSS THE AREA. HOWEVER...BY THE
END OF THE PERIOD INTO NEXT WEEKEND...IT APPEARS THAT A LARGE TROUGH
WILL DIG ACROSS THE WESTERN CONUS. THIS COULD RESULT IN AN
ENERGETIC STORM ACROSS THE THE CENTRAL CONUS. HOWEVER...AT THIS
TIME IT APPEARS THAT THE MAIN IMPACTS FROM THIS SYSTEM WILL NOT
AFFECT MY AREA THROUGH THE CURRENT FORECAST PERIOD.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* 010-040 WINDS GUSTING TO AROUND 20 KT CONTINUING THROUGH THE
AFTERNOON.
* SCT-BKN 030-035 CLOUDS NEXT HOUR OR TWO WITH DECREASING COVERAGE
CONTINUING THROUGH MID AFTERNOON.
MDB
//DISCUSSION...UPDATED 18Z...
NORTH-NORTHEAST WINDS CONTINUE AHEAD OF HIGH PRESSURE WHICH WILL
BUILD IN FROM THE WEST TONIGHT. WINDS CONTINUE TO GUST TO AROUND
20 KT ACROSS THE CHICAGO METRO CLOSER TO LAKE MICHIGAN WITH
AROUND 25 KT AT GYY. LAKE EFFECT CLOUDS CONTINUE FROM THE CHICAGO
TERMINALS EASTWARD BUT COVERAGE IS STARTING TO SCATTER AND EXPECT
THIS TREND TO CONTINUE WITH THE MOST ABUNDANT COVERAGE CLOSE TO
THE ILLINOIS SHORE AND ACROSS NORTHWEST INDIANA. WINDS WILL
DIMINISH THIS EVENING AS THE HIGH DRAWS CLOSER WITH LITTLE IN THE
WAY OF CLOUD COVER EXPECTED TO PERSIST INTO THE EVENING. NEXT
ISSUE WILL BE POTENTIAL FOR FOG DEVELOPMENT. EXPECT THAT RFD AND
DPA HAVE THE BEST CHANCE FOR AT LEAST PATCHY FOG OVERNIGHT. THE
AIRMASS THAT IS BUILDING INTO THE AREA IS DRIER BUT WITH FAIRLY
WET GROUND AND GOOD RADIATIONAL COOLING EXPECTED FOG SHOULD
DEVELOP. ALTERNATIVELY...DEW/FROST MAY QUICKLY DEVELOP AND
PRECLUDE MUCH FOG FROM FORMING. IF UPSTREAM OBS FROM THIS MORNING
ARE ANY INDICATION FOG WILL DEVELOP LATE TONIGHT. WILL CARRY MIFG
FOR NOW AT RFD/DPA BUT IFR FOG IS POSSIBLE. ORD/MDW/GYY SHOULD SEE
LITTLE IF ANY FOG DEVELOPMENT WITH WARMER OVERNIGHT TEMPS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM-HIGH CONFIDENCE IN WINDS 010-030 CONTINUING WITH HIGH
CONFIDENCE THAT THE CHANCE FOR WINDS TO TURN MORE NORTHERLY
TOWARD 350-360 LATE AFTERNOON IS LOW.
* HIGH CONFIDENCE IN CEILING FORECAST.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH FRIDAY...VFR.
JEE
&&
.MARINE...
246 PM CDT
WINDS ARE CONTINUING TO SLOWLY DIMINISH ACROSS THE LAKE THIS
AFTERNOON AS HIGH PRESSURE SPREAD FROM LAKE SUPERIOR SOUTHWARD INTO
IOWA AND MISSOURI SLOWLY DRIFTS EAST AND WEAKENS SLIGHTLY. SPEEDS
WILL REMAIN IN THE10 TO 20 KT RANGE NORTH THIS EVENING WITH 15 TO 25
KT ACROSS THE SOUTH HALF BUT THESE WILL DIMINISH TO 10 TO 15 KT
NORTH AND 10 TO 20 KT SOUTH TONIGHT. SPEEDS WILL REMAIN STEADY
ACROSS THE NORTH HALF SUNDAY BUT THERE MAY BE A SLIGHT INCREASE TO
THE 15-20 RANGE ACROSS THE SOUTH DURING THE DAY. DIRECTION WILL
REMAIN NORTH TO NORTHEAST INTO SUNDAY MORNING BUT SHOULD TURN
NORTH TO NORTHWEST AFTER THAT. WITH THE PERSISTENT NORTH TO
NORTHEAST WINDS WAVES WILL BE SLOW TO SUBSIDE ACROSS THE SOUTH END
OF THE LAKE. WILL NEED TO EXTEND THE SMALL CRAFT ADVISORY THROUGH
SUNDAY MORNING. THIS MAY NEED TO RUN LONGER FOR THE INDIANA
NEARSHORE IF WINDS PICK UP SLIGHTLY SUNDAY AFTERNOON AND KEEP
WAVES UP. GENERALLY LIGHT WINDS WILL THEN BE IN PLACE AS THE HIGH
PARKS OVER THE LAKE LATER SUNDAY AND REMAINS THERE THROUGH THE
EARLY PART OF NEXT WEEK. A VARIABLE NORTHERLY DIRECTION SHOULD
PREVAIL INTO TUESDAY BUT SHIFT TO A STEADIER SOUTHERLY DIRECTION
TUESDAY. SPEEDS WILL THEN PICK UP WEDNESDAY AS THE PRESSURE
GRADIENT INCREASES BUT THIS INCREASE LOOKS TO BE RATHER MODEST
WITH THE ABSENCE OF ANY SIGNIFICANT LOW PRESSURE SYSTEMS AFFECTING
THE REGION THROUGH THE WEEK.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 AM SUNDAY.
&&
$$
