325 AM CDT
MODEL SOLUTIONS SHOW THAT THE SEASONALLY TYPICAL ACTIVE AMPLIFIED
UPPER PATTERN CURRENTLY OVER THE NORTHERN HEMISPHERE WILL PERSIST
THROUGH NEXT WEEK THOUGH BY LATER NEXT WEEK THE PATTERN ACROSS
CENTRAL NORTH AMERICA BECOMES MORE ZONAL. BEFORE THEN A COUPLE
OF DISTURBANCES WILL BRING CHANCES OF PRECIPITATION TO THE
AREA...AND IN THEIR WAKE PULL VERY COOL AIR CURRENTLY OVER NORTH
CENTRAL CANADA SOUTHWARD ACROSS THE UPPER MIDWEST AND THE GREAT
LAKES.
THE NEXT CHANCE FOR RAIN WILL COME OVERNIGHT TONIGHT THROUGH
SUNDAY MORNING AS THE SHORT WAVE OVER SOUTHERN B.C. AND NORTHERN
WA EARLY THIS MORNING CONTINUES ON A EAST- SOUTHEAST TRACK ACROSS
THE NORTHERN PLAINS AND REACHING THE UPPER MS VALLEY BY 12Z
SUNDAY. COMPARED TO THEIR PREVIOUS RUNS THE MODELS ARE ALMOST ALL
IN AGREEMENT IN DECREASING THE QPF AMOUNTS ACROSS THE AREA AS
LOWER LEVELS WILL REMAIN RATHER DRY WITH A SURFACE RIDGE PROGGED
TO REMAIN STRETCHED FROM THE NORTHERN ROCKIES SOUTHEASTWARD ACROSS
THE CENTRAL PLAINS. DESPITE DRY LOW LEVELS RADAR ECHOES ARE
SPREADING ACROSS MT IN THE MID LEVEL WARM ADVECTION AHEAD OF THE
SHORT WAVE TROUGH. METARS FROM UNDER THE ECHOES REPORTING MAINLY
MID LEVEL CLOUDS AND SOME LIGHT RAIN REACHING THE GROUND. EXPECT
A SIMILAR SCENARIO OVER THE LOCAL AREA LATE TONIGHT AND SUNDAY
MORNING.
AFTER DRY CONDITIONS FROM LATER SUNDAY INTO LATER MONDAY THE
THREAT OF RAIN RETURNS FOR MONDAY NIGHT INTO TUESDAY. THE STRONG
SHORT WAVE CURRENTLY OVER THE GULF OF AK PROGGED TO MOVE ACROSS
THE NORTHERN ROCKIES SUNDAY NIGHT IS SHOWN TO DIG DEEPER
SOUTHEASTWARD ACROSS THE PLAINS BY ALL THE MODELS. WITH THE SHORT
WAVE NOW EXPECTED TO BE FURTHER SOUTH THE THREAT OF RAIN ALSO
SHIFTS SOUTH MORE TO CENTRAL AND SOUTHERN IL...THOUGH HAVE KEPT
SLIGHT CHANCE POPS ALL THE WAY TO THE WI BORDER GIVEN THE
STRENGTH OF THE SYSTEM. THE UPPER TROUGH IS PROGGED TO SHARPEN
OVER THE MID AND LOWER MS VALLEY DURING LATE MONDAY NIGHT AND
TUESDAY AS ITS AXIS SLOWLY SHIFTS TO THE EAST.
THE PASSAGE OF THE UPPER TROUGH WILL BRING AN END TO THE RAIN
CHANCES FROM THE SYNOPTIC SYSTEM LATER TUESDAY AND TUESDAY NIGHT.
HOWEVER...A STRENGTHENING NORTH TO NORTH-NORTHEAST LOW AND MID
LEVEL FLOW DEVELOPS DURING TUESDAY AND INTO WEDNESDAY ADVECTING
VERY COOL AIR SOUTHWARD ACROSS THE REGION. TEMPERATURES ARE
FORECAST TO FALL TO AS COLD AS -10C AT 2.5KM AGL BY TUESDAY
EVENING AND WITH LAKE MI WATER TEMPERATURES RANGING FROM 13C
NORTH TO 17C SOUTH A DEEP UNSTABLE SETUP CONDUCIVE FOR LAKE
EFFECT RAIN SHOWERS WILL BE IN PLACE. WITH AN EASTERLY COMPONENT
TO THE FLOW THROUGH THE CLOUD BEARING LAYER TUESDAY NIGHT INTO
EARLY WEDNESDAY MORNING THE WESTERN SHORES OF SOUTHERN LAKE MI
ARE TARGETED FOR THE LAKE EFFECT RAIN...AS WELL AS FAR NORTHWEST
IN. THE FLOW BACKS TO NORTHERLY WEDNESDAY NIGHT WHICH IS EXPECTED
TO SHIFT THE LAKE EFFECT SHOWERS FURTHER EAST AND CONFINE THEM TO
JUST NORTHWEST IN. CONTINUED BACKING DURING THURSDAY ALONG WITH
WARMING MID LEVELS WILL RESULT IN THE SHOWERS DIMINISHING AS WELL
AS SHIFTING FURTHER EAST AND OUT OF THE LOCAL FORECAST AREA.
TEMPERATURES WILL BE AROUND CLIMATOLOGICAL NORMALS FOR MID
OCTOBER THE NEXT COUPLE DAYS BEFORE COOLER AIR ARRIVES DURING
TUESDAY WITH HIGHS MIDWEEK ONLY IN THE LOWER 50S NORTH AND LOWER
TO MID 50S SOUTH. OVERNIGHT LOWS OUTSIDE OF THE CHICAGO URBAN
HEAT ISLAND EXPECTED TO DIP TO MID 30S TO LOWER 40S. WITH THE
UPPER FLOW BECOMING MORE ZONAL LATE IN THE WEEK AS MENTIONED
ABOVE TEMPERATURES ARE EXPECTED TO START MODERATING.
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* GUSTY WEST WINDS THROUGH EARLY TOMORROW EVENING.
* CHANCE OF RAIN AFTER MIDNIGHT TONIGHT
KREIN
//DISCUSSION...UPDATED 06Z...
AN AREA OF LOW PRESSURE CONTINUES TO MOVE OFF TO THE NORTHEAST...AS
AN AREA OF HIGH PRESSURE SLIDES FROM THE CENTRAL PLAINS INTO THE
LOWER MISSISSIPPI VALLEY TONIGHT. THE RESULTANT PRESSURE GRADIENT
BETWEEN THESE TWO SYSTEMS REMAINS STRONG AS THE DEEP LOW CONTINUES
TO DRAW COOLER AIR OUT OF THE NRN PLAINS AND SCNTRL CANADA. THE
COMBINATION OF THE STRONG PRESSURE GRADIENT AND COLD ADVECTION
WILL KEEP STRONG...GUSTY WINDS OVER NRN IL/NWRN INDIANA THROUGH
EARLY THIS EVENING...WHEN THE HIGH PRESSURE WILL BEGIN TO BUILD OVER
THE MIDWEST AND WINDS WILL BEGIN TO DIMINISH. EXPECT WESTERLY GUSTS
OF TO INCREASE THROUGH THE MORNING AND INTO THE EARLY
AFTERNOON...WITH PEAK GUSTS OF 25-30KT. GUSTINESS SHOULD SUBSIDE
AT ARND SUNSET.
THE NEXT CHANCE FOR PCPN WILL BE LATE TONIGHT OR EARLY TOMORROW
MORNING AS A MID LEVEL IMPULSE CURRENTLY DROPPING OUT OF THE
NORTHERN ROCKIES REACHES THE UPPER MIDWEST. LOW LEVELS ARE VERY
DRY AND THERE WILL BE LITTLE OPPORTUNITY FOR INCREASING LOW LEVEL
MOISTURE OVER THE AREA. SO...WILL ONLY INTRODUCE A PROB30 GROUP
FOR -RA AS THERE IS A GOOD CHANCE THAT THERE WILL BE MORE VIRGA
THAN ACTUAL RAIN REACHING THE GROUND.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* LOW CONFIDENCE IN PCPN FORECAST LATE IN THE PERIOD.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY THROUGH TUESDAY...VFR WITH PERIODIC RAIN CHANCES...SOME
MVFR POSSIBLE.
WEDNESDAY AND THURSDAY...VFR.
JEE
&&
.MARINE...
320 AM CDT
DEEP LOW PRESSURE JUST SOUTH OF JAMES BAY WILL MOVE TO SOUTHERN
HUDSON BAY AND CONTINUE TO DEEPEN TODAY AND TONIGHT AS HIGH PRESSURE
REMAINS OVER THE CENTRAL PLAINS. COLD ADVECTION AND A STRONG
PRESSURE GRADIENT WILL DRIVES GALES TO 45 KT OVER THE LAKE TODAY.
THERE IS THE POTENTIAL FOR A FEW STORM FORCE WIND GUSTS OVER THE
NORTHERN PORTIONS OF THE LAKE TODAY AS STRONG WINDS ALOFT MAY MIX
DOWN TO THE SURFACE. WINDS WILL SLOWLY DECREASE AND DROP BELOW GALE
FORCE LATE TONIGHT AS THE SURFACE LOW BEGINS TO WEAKEN AND MOVE OFF
TO THE EAST. WINDS OVER THE LAKE WILL REMAIN RATHER BRISK FOR THE
NEXT SEVERAL DAYS AS LOW PRESSURE DEEPENS AS IT MOVES ACROSS THE
LOWER MISSISSIPPI VALLEY TO THE SOUTHEASTERN CONUS...WHILE STRONG
HIGH PRESSURE BUILDS OVER THE NORTHERN PLAINS.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 1 AM SUNDAY.
GALE WARNING...NEARSHORE WATERS UNTIL 4
PM SATURDAY.
&&
$$
