252 PM CDT
FORECAST CHALLENGES TODAY INCLUDE THE UNSEASONABLY WARM TEMPS OVER
THE WEEKEND AND INTO NEXT WEEK...FOLLOWED BY THE RAIN/THUNDER
CHANCES NEXT WEEK.
PRETTY SPECTACULAR WEATHER ON TAP TO KICK OFF THE WEEKEND AS
VIGOROUS SHORTWAVE OFF THE SOUTHERN CALIFORNIA COAST WORKS TO CARVE
OUT A DEEP TROUGH OVER THE WESTERN CONUS...WITH UPPER RIDGE
AMPLIFYING OVER THE CENTRAL U.S. AS UPPER LOW CONTINUES TO PEEL
SOUTHEAST OFF TOWARD THE CAROLINA COAST. FAIRLY DRY CONDITIONS AND
VIRTUALLY CLEAR SKIES SHOULD ALLOW TEMPS TO FALL OFF FAIRLY QUICKLY
TONIGHT AND HAVE TRENDED LOWS A BIT BELOW GUIDANCE DESPITE THE
EXPECTATION OF A BIT OF WIND.
NEARLY FULL SUNSHINE...INCREASING SOUTHERLY FLOW/WARM ADVECTION AND
LOW DEWPOINTS SHOULD ALLOW FOR A HEALTHY REBOUND IN TEMPS SATURDAY.
GOING FORECAST LOOKS RIGHT ON TRACK WITH LOWER 60S SOUTHWEST CWA AND
UPPER 50S ELSEWHERE...THOUGH PROBABLY A COUPLE DEGREES COOLER ALONG
THE ILLINOIS LAKESHORE AS SLIGHT EASTERLY COMPONENT TO THE FLOW
CLIPS THE LAKE.
SURFACE LOW OVER THE PLAINS SATURDAY WILL THEN BEGIN TO DEEPEN AS IT
LIFTS NNE TOWARD WINNIPEG SATURDAY NIGHT INTO SUNDAY. THE RESULT
WILL BE STRENGTHENING SOUTHERLY WINDS AND IMPRESSIVE WARM AIR
ADVECTION KEEPING TEMPS UNSEASONABLY MILD SAT NIGHT WHICH WILL
PROVIDE A NICE SPRING BOARD FOR AN UNSEASONABLY WARM DAY SUNDAY.
STRONG LOW LEVEL JET SAT NIGHT SHOULD BE WORKING HARD TO TRANSPORT
WHAT LITTLE MODIFIED GULF MOISTURE THERE IS NORTHWARD INTO THE
REGION. HOWEVER...I AM SOMEWHAT LEARY OF JUST HOW AGGRESSIVE
GUIDANCE IS WITH THE RETURN OF MOISTURE AND RESULTANT STRATUS GIVEN
THE STRONG NORTHERLY FLOW AND INVASION OF CONTINENTAL AIR THAT IS
CURRENTLY SCRUBBING THE GULF OF LOW LEVEL MOISTURE. GIVEN THE
EXPECTATION OF AT LEAST PARTIAL SUNSHINE...HAVE GONE ABOVE GUIDANCE
FOR HIGHS SUNDAY WITH GENERALLY MID 60S...WHICH COULD END UP BEING
TOO CONSERVATIVE STILL. EVEN IF STRATUS MATERIALIZES...STRONG
SOUTHERLY WINDS...LIKELY GUSTING WELL OVER 30 MPH IN THE AFTERNOON
SHOULD ALLOW FOR 60S CWA WIDE SUNDAY AFTERNOON.
WEAKENING FRONTAL BOUNDARY WILL SAG SOUTH INTO THE AREA SUNDAY NIGHT
AND THEN STALL OUT OVER OR NEAR THE AREA MONDAY AS TROUGH RELOADS
OUT WEST. THE STALLED FRONT COULD PROVIDE THE FOCUS FOR SOME SHOWERS
SUNDAY NIGHT INTO MONDAY...BUT THIS IS NOT LOOKING TO BE A BIG
DEAL AS CWA WILL LIE BETWEEN SHORTWAVES AND WITHOUT SIGNIFICANT
FORCING. WESTERN TROUGH PROGGED TO BEGIN EJECTING OUT MONDAY NIGHT
WITH VERY STRONG (50-60KT) LOW LEVEL JET LIKELY TO RESULT IN VERY
IMPRESSIVE MOISTURE TRANSPORT (4+ STANDARD DEVIATIONS ABOVE
AVERAGE) WHICH SHOULD SUPPORT FAIRLY WIDESPREAD
SHOWER/THUNDERSTORM DEVELOPMENT ALONG RETREATING/STRENGTHENING
WARM FRONT MONDAY NIGHT.
MEDIUM RANGE MODELS HAVE SLOWED THE PROGRESS OF THIS SYSTEM A BIT
BUT CONTINUE TO ADVERTISE A POWERFUL SLIGHTLY NEGATIVELY TILTED
CLOSED LOW LIFTING NORTHEAST INTO THE MIDWEST TUESDAY NIGHT INTO
WEDNESDAY. DESPITE CLOUD COVER AND SOME OCCASIONAL SHOWERS/STORMS
IT STILL LOOKS LIKE AN UNSEASONABLY DAY TUESDAY WITH HIGHS WELL INTO
THE 60S. MULTIPLE DAYS OF RETURN FLOW FROM THE GULF...INCLUDING
24-36 HOURS OF LOW LEVEL FLOW ORIGINATING FROM THE WESTERN CARIBBEAN
SHOULD PROVIDE FOR A RESPECTABLY MOIST PRE-FRONTAL AIRMASS FOR
NOVEMBER. WHILE THERE ARE SOME MINOR TRACK/TIMING DIFFERENCES AMONG
THE VARIOUS MODELS...GENERAL SYNOPTIC PATTERN CERTAINLY LOOKING
FAVORABLE FOR A FALL SEVERE WEATHER EVENT SOMEWHERE IN THE REGION
TUESDAY NIGHT OR WEDNESDAY.
QUICK SHOT OF COLD AIR FOLLOWING THE SYSTEM...THOUGH IT DOES APPEAR
AS IF TROUGH SHOULD LIFT OUT QUICKLY ENOUGH TO SCOUR OUT MOISTURE
BEFORE THE COLDER AIR ARRIVES LIMITING THE POTENTIAL FOR ANY
CHANGE OVER TO SNOW.
IZZI
&&
.FIRE WEATHER...
243 PM CDT
STRONG SOUTHERLY WINDS AND UNSEASONABLY WARM CONDITIONS ARE
LIKELY SUNDAY AFTERNOON. AS IS OFTEN THE CASE...THERE ARE
QUESTIONS REGARDING HOW QUICKLY DEWPOINTS WILL RISE AS MOISTURE
RETURNS NORTHWARD. CURRENTLY LOOKS LIKELY THAT RELATIVE HUMIDITY
VALUES WILL REMAIN ABOVE RED FLAG THRESHOLDS...HOWEVER SOUTH WINDS
OF 20-30 MPH WITH GUSTS POSSIBLY UP TO 40 MPH WITH RH POSSIBLY
DROPPING BELOW 40 PERCENT COULD STILL RESULT IN HEIGHTENED FIRE
DANGER. THE GREATEST FIRE DANGER/LOWEST RH VALUES ARE EXPECTED
SOUTHEAST OF I-55 IN ILLINOIS INTO NORTHWEST INDIANA.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* NONE.
ALLSOPP
//DISCUSSION...UPDATED 18Z...
HIGH PRESSURE CENTERED OVER THE GREAT LAKES WAS BRINGING CLEAR
SKIES AND LIGHT EAST WINDS TO THE REGION. WINDS WILL GRADUALLY
TURN SOUTHEAST OVERNIGHT AS THE HIGH PRESSURE SHIFTS TO THE
EASTERN US. WINDS WILL TURN MORE SOUTHERLY AND INCREASE IN SPEED
SATURDAY AFTERNOON AS STRONG LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAINS. A COMBINATION OF A VERY DRY AIRMASS...THIN CIRRUS
OVERHEAD...AND SOUTHEAST WINDS 5 TO 10 KT SHOULD PRECLUDE ANY
SIGNIFICANT FOG DEVELOPMENT LATE TONIGHT/SATURDAY MORNING.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN ALL ELEMENTS OF FORECAST.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...VFR.
SUNDAY...VFR. CHC SHRA IN THE AFTN.
MONDAY...VFR. SHRA ISO/TSRA WITH PATCHY MVFR.
TUESDAY...VFR. SHRA ISO/TSRA WITH PATCHY MVFR.
WEDNESDAY...VFR. SHRA.
THURSDAY...VFR. CHC SHRA PSBLY MIXED WITH SN AND PATCHY MVFR.
BEACHLER
&&
.MARINE...
230 PM CDT
HIGH PRESSURE OVER THE LAKE TODAY WILL ALLOW FOR LIGHTER WINDS...BUT
LOW PRESSURE DEVELOPING OVER THE CENTRAL PLAINS ON SATURDAY WILL
CAUSE WINDS TO VEER AROUND TO THE SOUTH AND GRADUALLY INCREASE
THROUGH THE DAY. WINDS ARE EXPECTED TO REACH GALE FORCE DURING THE
DAY ON SUNDAY AND PEAK DURING THE LATE AFTERNOON AS THE LOW CENTER
MOVES NORTH INTO MANITOBA. THE PRESSURE GRADIENT AND RESULTANT WINDS
WILL BE STRONGEST OVER THE NORTHERN HALF OF THE LAKE...WHERE WINDS
UP TO 45 KT ARE FORECAST. WINDS WILL DIMINISH SOME TO BACK BELOW
GALES EARLY MONDAY AS A WEAK COLD FRONT MOVES THROUGH THE AREA AND
THE PRESSURE GRADIENT BECOMES MORE BAGGY. HIGH PRESSURE BUILDS
ACROSS THE AREA BRIEFLY ON MONDAY...BUT THE NEXT LOW PRESSURE
SYSTEM IS ALREADY TAKING SHAPE OVER THE CENTRAL PLAINS ON TUESDAY
AND IS FORECAST TO LIFT NORTH ACROSS LAKE MICHIGAN ON WEDNESDAY.
MODELS HAVE MODEST DIFFERENCES IN TRACKS...BUT THERE ARE SOME MORE
SIGNIFIANT DIFFERENCES PERTAINING TO THE STRENGTH OF THE LOW.
SHOULD ONE OF THE DEEPER SOLUTIONS VERIFY...WILL HAVE TO RAMP UP
WIND FORECAST FOR LATE TUESDAY THROUGH WEDNESDAY...BUT OPTED TO
KEEP THE MORE MODEST BLENDED MODEL WINDS FOR NOW. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
