334 AM CDT
MAIN CONCERNS FOR LATEST FORECAST PACKAGE WILL BE DEALING WITH WEAK
COLD FRONT LATE IN THE WEEKEND AND ANOTHER LOW PRESSURE SYSTEM
MIDWEEK.
FOR TODAY...QUIET WEATHER EXPECTED AS TEMPERATURES WARM NICELY INTO
THE MID TO UPPER 60S NORTH OF INTERSTATE 80...AND LOW 70S TO THE
SOUTH THANKS TO H85 THERMAL RIDGE ADVECTING ACROSS THE REGION. AS
THIS BEGINS TO MOVE EAST OF THE REGION THIS EVENING...A WEAK SURFACE
TROUGH WILL PUSH THROUGH THE AREA. WITH VERY WEAK OMEGA VALUES AND
PWATS OF HALF INCH OR LESS...NO CONCERNS FOR ANY WEATHER WITH
THIS...MAINLY JUST AN INCREASE IN MID LEVEL CLOUDINESS POSSIBLE. BY
LATE SUNDAY...A MODEST UPPER LEVEL WAVE WITH WEAK SURFACE REFLECTION
WILL PASS JUST NORTH OF THE AREA. MODELS CONTINUE TO SPLATTER SOME
LIGHT QPF OVER THE CWA...BUT MAIN ENERGY WITH WAVE WILL PASS NORTH
OF ILLINOIS...AND WE SHOULD BE UNDER THE CONVERGENT QUADRANT OF
WEAKENING 100+KT JET DIPPING SOUTH INTO THE UPPER MIDWEST. LOW AND
MID LEVEL LAPSE RATES DO STEEPEN HOWEVER...AND VERY WEAK CAPE MAY BE
SUFFICIENT TO SUPPORT A FEW SHOWERS DEVELOPING IN RESPONSE TO MODEST
BOUNDARY LAYER CONVERGENCE ALONG THE FRONTAL BOUNDARY...THUS WILL
KEEP GOING THE LOW POPS FOR SUNDAY AFTERNOON/EVENING PERIODS...BUT
BY NO MEANS THINK THIS WILL MAKE THE DAY A WASH.
WARM ADVECTION BEGINS TO RAMP UP THE LATTER HALF OF MONDAY AS THE
FRONTAL BOUNDARY STALLS SOUTH OF THE FORECAST AREA AND BEGINS TO
LIFT BACK NORTH AS LOW PRESSURE DEEPENS OVER THE CENTRAL PLAINS IN
RESPONSE TO DIGGING H5 WAVE. TRACK OF THIS LOW IS STILL
UNCERTAIN...GFS BRINGS THE TRACK OVER NORTHERN ILLINOIS...WHILE
GEM/ECMWF SUGGEST A FARTHER NORTH SOLUTION...TAKING AN OCCLUDED LOW
OVER NORTHERN WISCONSIN. GFS SUGGESTS CHANCES OF SHOWERS AND
THUNDERSTORMS AS THE WARM FRONT LIFTS THROUGH...BUT THE EC KEEPS HAS
US WELL INTO THE WARM SECTOR...WITH PRECIP CHANCES BEING ALONG A
TRAILING COLD FRONT. CURRENT POPS ARE MORE OR LESS A BLEND OF THESE
SOLUTIONS...THOUGH IT IS WORTH NOTING THAT THE GFS TRACK AS BEEN
SOMEWHAT CONSISTENT WHILE THE ECMWF HAS BOUNCED AROUND A BIT. THE
00Z RUN OF THE NAM AT 84HRS...WHILE ONLY MONDAY NIGHT...ALSO SEEMS
TO BE TAKING MIDDLE GROUND ON THE LOW TRACK.
THE COLD FRONT WILL VERY SLOWLY SAG SOUTH OF THE AREA WEDNESDAY WITH
COLD AIR ALOFT ALSO TRICKLING SOUTH. H85 TEMPS BOTTOM OUT AROUND -4
TO -6 WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS UPPER LEVEL TROUGH
AMPLIFIES OVER THE AREA. AFTERNOON HIGHS ON THOSE DAYS WILL TOP OUT
BELOW NORMAL...RIGHT AROUND 50F. GFS IS SLOW TO PUSH THE FRONTAL
BOUNDARY AWAY FROM THE CWA...WITH LINGERING POPS OVER THE AREA INTO
THURSDAY. DESPITE BROAD HEIGHT FALLS ALOFT...FOCUS SHOULD BE FARTHER
SOUTH ALONG THE FRONTAL BOUNDARY...ESPECIALLY FRIDAY AS UPPER LOW
BEGINS TO CUT OFF ACROSS THE LOW TO MID MISSISSIPPI VALLEY...AND
SUSPECT POPS LOCALLY MAY BE A BIT OVERDONE. WILL HAVE TO MONITOR
MODEL TRENDS CLOSELY WHICH CURRENTLY BRING THIS NEXT SYSTEM UP THE
ATLANTIC COAST NEXT WEEKEND...THOUGH IF HISTORY REPEATS ITSELF...WE
MAY SEE THIS LOW TRACKING FARTHER INLAND WITH IMPACTS LOCALLY. BMD
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NONE
IZZI
//DISCUSSION...UPDATED 06Z...
WEATHER NIL.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...SLIGHT CHC SHRA.
MONDAY...VFR.
TUESDAY...CHC SHRA AND TSRA.
WEDNESDAY...SLT CHC SHRA.
THURSDAY...SLT CHC SHRA.
KJB
&&
.MARINE...
245 AM CDT
WEAK TROUGH WILL SWEEP ACROSS THE LAKE THIS AFTERNOON BUT WITHOUT
MUCH FANFARE. SOUTHERLY WINDS WILL INCREASE SUNDAY AS THE GRADIENT
TIGHTENS IN ADVANCE OF A LOW TRACKING NORTH OF LAKE SUPERIOR.
FAIRLY WARM AIR BEING ADVECTED NORTH WILL RESULT IN SOMEWHAT
MARINE BOUNDARY LAYER...ESPECIALLY SOUTHERN PORTIONS OF THE LAKE.
STILL ANTICIPATE WINDS GUSTING WELL INTO THE 20 KT RANGE SUNDAY
AFTERNOON OVER NORTHERN PORTIONS OF THE LAKE BEFORE FRONT MOVES
THROUGH WITH A BRIEF PERIOD OF FRESH NORTHWEST WINDS MONDAY.
WINDS SUBSIDE FOR A TIME MONDAY NIGHT BEFORE THE NEXT STORM
APPROACHES THE REGION TUESDAY AND WEDNESDAY. STILL SIGNIFICANT
DIFFERENCES IN THE MODELS WITH REGARDS TO STRENGTH AND TRACK OF
THIS LOW SO HAVE LOWER THAN AVERAGE CONFIDENCE IN THE TUES/WED
FORECAST...BUT POTENTIAL DOES EXIST FOR FAIRLY STRONG WINDS JUST
THE DIRECTION IS TOUGH TO PINPOINT AT THIS POINT.
IZZI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FROST ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ021-
ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 8 AM SATURDAY.
IN...FROST ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 8 AM
SATURDAY.
LM...NONE.
&&
$$
