1159 AM CDT
LATE THIS AFTERNOON THROUGH SUN NIGHT...
UPPER LOW OVER QUEBEC AT MIDDAY WILL CONTINUE TO MOVE NE AND ACROSS
LABRADOR TONIGHT. AS IT DOES THE UPPER TROUGH TRAILING SW ACROSS THE
CENTRAL GREAT LAKES WILL CONTINUE OFF TO THE E WHILE AN UPSTREAM
SHORT WAVE MOVES FROM SOUTHERN MANITOBA AND THE NORTHERN PLAINS
EASTWARD...REACHING WESTERN QUEBEC AND THE UPPER MIDWEST BY 12Z SAT.
THIS SYSTEM WILL BE MOISTURE STARVED WITH ONLY AN INCREASE IN HIGH
AND SOME MID LEVEL CLOUDINESS OCCURRING OVERNIGHT WHICH WILL LIMIT
PROSPECTS OF FROST TO THE SE QUARTER OF THE FORECAST AREA AS CLOUDS
ARE NOT EXPECTED TO ARRIVE THERE TIL THE PREDAWN HOURS.
THIS SHORT WAVE PUSHES A WEAK COLD FRONT ACROSS THE NORTHERN AND
WESTERN PORTIONS OF THE LOCAL AREA DURING SAT AFTERNOON AND NIGHT
BUT WITH MINIMAL SHALLOW COLD AIR ADVECTION. THIS ALONG WITH THE
TIMING OF THE FRONT NOT UNTIL AFTERNOON AT THE EARLIEST TEMPERATURES
FOR SAT SHOULD BE ABLE TO REACH THE LOWER AND MID 60S.
WARM AIR ADVECTION TO BE OCCURRING FROM THE CENTRAL PLAINS TO THE
UPPER MIDWEST AND MS VALLEY SAT NIGHT INTO SUN AHEAD OF THE STRONGER
SHORT WAVE...CURRENTLY JUST REACHING SE AK AND THE B.C. COAST AT
MIDDAY...AS IT MOVES ACROSS S CENTRAL CANADA AND THE NORTHERN
PLAINS. WITH 850HPA TEMPS AVERAGING AROUND 7C DURING SUN AFTERNOON
SO THE MID AND UPPER 60S FROM MOS LOOK ON TRACK. THE SHORT WAVE
TROUGH CONTINUES E OVER THE WESTERN GREAT LAKES SUN EVENING
DRAGGING ANOTHER COLD FRONT...THIS ONE A BIT STRONGER...E ACROSS
THE FORECAST AREA BY MON MORNING. MOISTURE REMAINS LIMITED AND
WITH STRONGER DYNAMICS INCLUDING LEFT EXIT REGION OF UPPER JET
MOVING OVER MN AND WI HAVE ONLY SLIGHT CHANCE POPS SUN AFTERNOON
WITH THIS SYSTEM.
SUN NIGHT THROUGH FRI...
SLIGHT CHANCE OF SHOWERS TO LINGER OVER THE LOCAL FORECAST AREA
INTO SUN NIGHT UNTIL THE STORM SYSTEM OVER QUEBEC MOVES FARTHER E
AND THE TRAILING COLD FRONT SAG S THROUGH THE FORECAST AREA. MON
EXPECTED TO BE DRY AS BROAD RIDGING ALOFT MOVES OVER THE REGION
BETWEEN AN UPPER LOW OVER SOUTHERN HUDSON BAY AND THE POSITIVE
TILT TROUGH MOVING ACROSS WESTERN N AMERICA.
AS THE UPPER TROUGH AXIS CONTINUES E TUE ALONG A WESTERN ONTARIO
TO SOUTHERN HIGH PLAINS LINE BY EVENING THE ASSOCIATED SURFACE LOW
WILL BE EJECTING NE FROM THE CENTRAL PLAINS. MODELS SHOWING
RATHER SIGNIFICANT VARIATIONS IN PLACEMENT OF THE SURFACE LOW AT
00Z WED...RANGING FROM CENTRAL IL TO CENTRAL WI...OR ABOUT 300 MI
N TO S. TRACK OF THE LOW OBVIOUSLY WILL HAVE CRITICAL ROLE IN
TEMPERATURES AND RAIN CHANCES. FOR NOW WILL FIGURE ON A TRACK
ALONG OR NEAR THE IL-WI BORDER. SURFACE LOW CONTINUES
NORTHEASTWARD INTO THE CENTRAL GREAT LAKES TUE NIGHT BUT THE UPPER
TROUGH AXIS DOES NOT MOVE E OF THE FORECAST AREA UNTIL THU
AFTERNOON SO HAVE SLIGHT CHANCE POP NUMBERS TIL THE PASSAGE OF THE
UPPER TROUGH. ANOTHER UPPER TROUGH MOVES OVER THE AREA FRI BUT
LOOKS TO BE MOISTURE DEPRIVED FOR THE MOST PART.
AFTER BEING MILD FOR THE SEASON THROUGH THE WEEKEND INTO EARLY
NEXT WEEK TEMPERATURES GO WELL BELOW NORMAL MID AND LATE NEXT
WEEK AS MID AND UPPER FLOW TURNS TO NORTHWESTERLY AND ADVECTS
COLD AIR FROM CENTRAL CANADA ACROSS THE REGION. WITH THE UPPER
TROUGH SHARPENING OVER THE GREAT LAKES...OH VALLEY...LOWER MS
VALLEY AND THE SOUTHEASTERN STATES THU AND FRI THE COLD ARE WILL
BE PULLED FARTHER S ACROSS THE CENTRAL AND EASTERN U.S.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* NO SIGNIFICANT CONCERNS.
RATZER/KJB
//DISCUSSION...UPDATED 18Z...
VFR CONDITIONS EXPECTED TO PERSIST THROUGH SATURDAY. SURFACE HIGH
PRESSURE RIDGE AXIS WILL MOVE EAST ACROSS TERMINALS THIS AFTERNOON
AND EARLY THIS EVENING...ALLOWING GRADUAL SHIFT FROM LIGHT
NORTHWEST TO LIGHT SOUTHWEST WINDS. WEAKENING TROUGH/COLD FRONT
MOVES INTO THE MISSISSIPPI VALLEY ON SATURDAY...MAINTAINING
SOUTHWEST FLOW AHEAD OF IT ACROSS THE TERMINALS. DRY LOW AND MID
LEVELS SHOULD PRECLUDE MUCH IN THE WAY OF CLOUDS EXCEPT FOR SOME
PATCHY HIGH CIRRUS LATER TONIGHT AND SATURDAY.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE ALL ELEMENTS.
RATZER/KJB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR.
SUNDAY...CHC SHRA.
MONDAY...VFR.
TUESDAY...CHC SHRA AND SLT CHC TSRA.
WEDNESDAY...SLT CHC SHRA.
THURSDAY...SLT CHC SHRA.
BMD
&&
.MARINE...
245 PM CDT
A RIDGE OF HIGH PRESSURE HAS BUILT INTO THE TENNESSEE VALLEY...AND
WILL CONTINUE TO PROVIDE AN INFLUENCE ON THE GREAT LAKES WEATHER
THROUGH SATURDAY. AS A RESULT THE PRESSURE GRADIENT HAS STEADILY
ERODED...WITH LIGHT NORTHWEST WINDS. THIS RIDGE OF HIGH PRESSURE IS
EXPECTED TO SLOWLY DRIFT EAST SATURDAY AND ALLOW WINDS TO BACK TO
THE SOUTHWEST ACROSS LAKE MICHIGAN. A WEAK TROUGH OF LOW
PRESSURE WILL MOVE ACROSS THE WESTERN LAKES SATURDAY AND THEN IS
EXPECTED TO DISSIPATE AS LOW PRESSURE MOVES ACROSS MANITOBA
SATURDAY EVENING...AND WILL CONTINUE TO SLIDE EAST INTO ONTARIO
SUNDAY AFTERNOON. GUIDANCE HAS CONTINUED TO INDICATE THE PRESSURE
GRADIENT WILL TIGHTEN SUNDAY EVENING...ALLOWING WINDS TO INCREASE
FROM THE SOUTHWEST TO 15 TO 25 KT. THEN A COLD FRONT IS EXPECTED TO
PUSH THROUGH THE WESTERN GREAT LAKES REGION EARLY MONDAY WITH WINDS
BECOMING WESTERLY FOR MONDAY.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ022-ILZ023-ILZ033-ILZ039...4 AM SATURDAY TO
8 AM SATURDAY.
IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...4 AM
SATURDAY TO 8 AM SATURDAY.
LM...NONE.
&&
$$
