315 AM CDT
PRIMARY FORECAST CHALLENGES THIS MORNING INCLUDE TEMPS TUES AND THE
SUBSEQUENT PRECIP CHANCES WITH WAVY FROPA.
UPPER TROUGH AND ASSOCIATED WEAK COLD FRONT CURRENTLY SWEEPING
ACROSS THE CWA SHOULD CLEAR THE AREA BY SUNRISE. THIS SHOULD SET
THE STAGE FOR ANOTHER SPECTACULAR AUTUMN DAY WITH SUNNY SKIES AND
SLIGHTLY ABOVE AVERAGE TEMPERATURES...THOUGH LIKELY SEVERAL
DEGREES COOLER THAN SUNDAY.
SHORTWAVE TROUGH CURRENTLY MAKING LANDFALL OVER THE PACIFIC
NORTHWEST IS PROGGED TO CONTINUE EASTWARD WITH LEE SIDE LOW FORECAST
TO DEVELOP TONIGHT WITH WARM FRONTOGENESIS TAKING PLACE EAST OF THIS
LOW INTO SOUTHERN WISCONSIN. SOUTHERLY WINDS WILL BEGIN TO RAMP UP
EVEN LATE TONIGHT WHICH WILL LIKELY RESULT IN TEMPS LEVELING OFF
EARLY AND EVEN BEGIN TO RISE SLOWLY LATE TONIGHT...ESPECIALLY
WESTERN CWA. WITH CWA PROGGED TO BE SOLIDLY LOCATED SOUTH OF THE
WARM FRONT WOULD ANTICIPATE ASSOCIATED SHOWER/THUNDERSTORM ACTIVITY
TONIGHT TO DEVELOP NORTH OF THE WISCONSIN BORDER.
TEMPERATURES TUESDAY ARE GOING TO BE QUITE TRICKY. LOW LEVEL
MOISTURE SHOULD BE RATHER SLOW TO RETURN...SO STRATUS/CUMULUS
SHOULDNT BE MUCH OF A FACTOR UNTIL VERY LATE IN THE DAY. GFS/WRF-NAM
BOTH SUGGEST THAT THE BRUNT OF THE CIRRUS SHOULD REMAIN NORTH OF OUR
CWA IN CLOSER PROXIMITY TO THE 120KT UPPER LEVEL JET. BIGGEST WILD
CARD IS POTENTIAL FOR MID LEVEL CLOUDINESS...WHICH GIVEN THE PROGGED
DRAMATIC STEEPENING OF MID LEVEL LAPSE RATES...IT WOULDNT BE HARD TO
ENVISION FAIRLY EXTENSIVE ALTOCUMULUS DECK WITH EVEN SOME POTENTIAL
FOR VIRGA/LIGHT SHOWERS. GIVEN THIS...HAVE REMAINED MODESTLY
CONSERVATIVE WITH HIGH TEMPS...HOWEVER IF MID LEVEL CLOUD DECK
DOESNT MATERIALIZE EARLY ENOUGH OR EXTENSIVELY ENOUGH THEN RECORD
HIGHS COULD BE IN JEOPARDY.
MODELS HAVE COME AROUND TO A SOLUTION MUCH LIKE WHAT PREVIOUS
WRF-NAM RUNS HAD BEEN SHOWING WITH A MUCH LESS AMPLIFIED UPPER
TROUGH AND WEAKER/FARTHER SOUTH SURFACE LOW TRACK. MINIMAL HEIGHT
FALLS...WEAKER LARGE SCALE ASCENT...AND SOMEWHAT MEAGER MOISTURE
RETURN ALL DONT BODE PARTICULARLY WELL REGARDING THE PROSPECTS FOR
BREAKING THE CAP ASSOCIATED WITH THE IMPRESSIVE EML THAT IS
PROGGED TO ADVECT EASTWARD INTO THE AREA. WILL MAINTAIN CHANCE
POPS FOR SHOWERS/THUNDERSTORMS...BUT HAVE BACKED OFF SOMEWHAT ON
THE VALUES GIVEN THE TENDENCY TOWARD A LESS AMPLIFIED SOLUTION.
SURFACE FRONT SHOULD SWEEP ACROSS THE CWA TUESDAY EVENING BEFORE
STALLING OUT TO OUR SOUTH AS ANOTHER WIGGLE IN THE UPPER FLOW
MIGRATES NORTHEASTWARD. MODELS DIFFER WITH RESPECT TO THE AMPLITUDE
OF THIS WAVE AND SUBSEQUENTLY WHAT/IF ANY IMPACTS IT WILL HAVE ON
OUR CWA. GIVEN THE WRF-NAM'S RECENT PERFORMANCE HANDLING THIS SYSTEM
AND SINCE MANY MODELS HAVE BEGUN TO TREND THIS WAY...HAVE OPTED TO
HIT RAIN CHANCES HARDER FOR WEDNESDAY. IF WRF-NAM WERE TO VERIFY
WEDNESDAY WOULD BE A PRETTY DISMAL DAY WITH RAIN...LOW CLOUDS...AND
A STIFF NORTH WIND KEEPING TEMPS NEARLY STEADY OR EVEN FALLING
SLOWLY INTO 40S.
RE-ENFORCING SHOT OF COLD AIR IS SCHEDULED TO ARRIVE FRIDAY AS
ANOTHER SHORTWAVE HELPS RE-ESTABLISH THE TROUGH OF THE NE CONUS AND
EASTERN CANADA. HAVE MAINTAINED SOME SMALL PRECIP CHANCES WITH THIS
FROPA BUT GENERALLY EXPECTING DRY AND SEASONABLY COOL WX TO PERSIST
LATE THIS WEEK INTO THE WEEKEND.
IZZI
&&
.FIRE WEATHER...
315 AM CDT
TUESDAY AFTERNOON WILL NEED TO BE MONITORED FOR POTENTIAL INCREASED
FIRE DANGER AS UNSEASONABLY WARM CONDITIONS AND STRONG WINDS ARE
EXPECTED. ONE OF THE BIGGER WILD CARDS IS WITH RESPECT TO HOW MUCH
CLOUDINESS THERE WILL BE...SHOULD CLOUDS END UP BEING LESS PROMINENT
THEN SUNSHINE WOULD LIKELY RESULT IN BETTER MIXING. THIS WOULD
LIKELY RESULT IN WARMER TEMPERATURES...LOWER DEWPOINTS/RH...AND
STRONGER WIND GUSTS. AT THIS POINT THE POTENTIAL FOR RED FLAG
CRITERIA BEING MET APPEARS LOW...BUT IT WOULDNT BE TOO GREAT OF A
STRETCH FOR THERE TO BE WIND GUSTS OVER 30 MPH AND RH VALUES
DROPPING TO 30-35 PERCENT. THE GREATEST POTENTIAL FOR CONDITIONS TO
BECOME MORE PROBLEMATIC FOR FIRE WEATHER WILL BE OVER NORTHWEST
INDIANA AND SOUTH OF INTERSTATE 80 IN ILLINOIS. FARTHER NORTH AND
WEST CLOUD COVER AND SLIGHTLY HIGHER RH SHOULD LESSEN THE FIRE
WEATHER DANGER SOMEWHAT.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WEST WINDS...WITH AN OCCNL MID TEEN GUST INTO THE EARLY EVENING
* GUSTY SOUTHERLY WINDS TUESDAY
* MORNING LLWS
* CHANCES FOR SHRA/TSRA TUESDAY LATE AFTERNOON
SHEA
//DISCUSSION...UPDATED 18Z...
WEAK SURFACE RIDGING CONTINUES TO MOVE ACROSS SOUTHERN AND CENTRAL
ILLINOIS...AND WINDS ACROSS ALL TERMINALS HAVE BECOME WESTERLY
THROUGH THE AFTERNOON HOURS. THERE MAY BE THE OCCNL GUST INTO THE
LOWER TO MIDDLE TEENS THROUGH THE EARLY EVENING...BUT THE MAJORITY
OF THE TIME WILL BE SEE WITHOUT GUSTS. WINDS WILL TURN SOUTHERLY
AS THE RIDGE MOVES EAST OVERNIGHT. A SURFACE LOW IS FORECAST TO
DEVELOP ACROSS WESTERN NEBRASKA LATER THIS AFTERNOON...AND SLIDE
EAST ACROSS THE REGION INTO TOMORROW. AS THIS HAPPENS...AN
ELEVATED WARM FRONT WILL LIFT NORTH ACROSS THE TERMINALS...AND A
VERY STRONG LOWER LEVEL JET WILL PUNCH ACROSS THE TERMINALS IN THE
MORNING HOURS. FROM ROUGHLY THE 10-11Z TIME FRAME THROUGH ROUGHLY
15-16Z...50 TO 55 KT WINDS AT OR AROUND 2 KFT WILL REMAIN ALOFT.
DUE TO THIS...WILL KEEP THE MENTION OF LLWS THROUGH 15Z...WHEN
MIXING IS EXPECTED TO INCREASE AND TRANSPORT SOME OF THE HIGHER
MOMENTUM AIR DOWN...ALLOWING GUSTS INTO THE 25 KT RANGE. THE
OVERALL TRACK OF THE SURFACE LOW WILL PLAY A CRITICAL ROLL INTO
THE OVERALL TIMING OF PRECIPITATION...AND HOW MUCH THUNDER IS
EXPECTED. FOR NOW...EXPECTING THE CHANCES FOR SHOWERS WITH
EMBEDDED THUNDER TO INCREASE IN LIKELIHOOD BEYOND 21Z
TOMORROW...WITH THE BEST CHANCES AS THE LOW PASSES OVERHEAD AND
THE COLD FRONT SLIPS BY...WHICH IS LATER THAN THE PRESENT TAFOR.
CIGS SHOULD REMAIN VFR THROUGH THE PERIOD AND ARE NOT EXPECTED TO
FALL TO LIKELY IFR LEVELS UNTIL THE COLD AIR ADVECTION REGIME
TAKES OVER LATE TUESDAY NIGHT AND INTO WEDNESDAY MORNING.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS THROUGH THE EVENING
* MEDIUM CONFIDENCE IN LLWS FORECAST/INTENSITY
SHEA
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...STRONG/GUSTY WESTERLY WINDS SHIFTING NORTH. MVFR
CIGS POSSIBLE LATE. CHANCE OF SHRA. CHANCE OF TSRA.
WEDNESDAY...MVFR/IFR POSSIBLE EARLY. CHANCE OF SHRA.
THURSDAY AND FRIDAY...SLIGHT CHANCE OF SHRA.
SATURDAY AND SUNDAY...VFR.
JEE
&&
.MARINE...
229 PM CDT
A COLD FRONT MOVED THROUGH THE REGION LAST NIGHT LEAVING
NORTHWEST FLOW IN ITS WAKE...BUT THIS FRONT WILL LIFT BACK NORTH
OVERNIGHT WITH WINDS COMING BACK AROUND TO THE SOUTHWEST AS HIGH
PRESSURE PUSHES EAST ACROSS THE CENTRAL PLAINS. THE PRESSURE
GRADIENT WILL TIGHTEN AHEAD OF THE LOW ON TUESDAY WITH WINDS
INCREASING INTO THE 20 TO 25 KT RANGE...WITH OCCASIONAL GUSTS
AROUND 30 KT...ACROSS SOUTHERN LAKE MICHIGAN. THIS MAY PROMPT A
SMALL CRAFT ADVISORY FOR SOME OF THE INDIANA AND ILLINOIS
NEARSHORE WATERS. WINDS WILL BEGIN TO DIMINISH BY LATE TUESDAY
EVENING AS THE LOW TRACKS ACROSS SOUTHERN LAKE MICHIGAN. WINDS
WILL RETURN TO NORTHERLY BEHIND THE LOW AND ONCE AGAIN INCREASE TO
AROUND 25 KT THROUGH WEDNESDAY EVENING UNTIL HIGH PRESSURE BEGINS
TO BUILD ACROSS THE LAKE FROM THE NORTH ALLOWING WINDS TO
DIMINISH.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
