747 PM CDT
MINOR ADJUSTMENTS TO THE GOING FORECAST. RAIN SHOWERS CONTINUE TO
SPOT THE AREA...HOWEVER SOME DRY AIR CONTINUES TO LIMIT THE
EXPANSE OF PRECIP ACROSS NORTHERN IL/NORTHWEST IN. GUIDANCE
CONTINUES TO INDICATE THAT THIS DRY AIR WILL SHRINK IN COVERAGE AS
ADDITIONAL MOISTURE ADVECTS NORTH/NORTHWEST AHEAD OF THE
DEVELOPING SHORTWAVE. OVERNIGHT LOWS IN THE LOW/MID 40S CONTINUES
TO LOOK ON TRACK. IN ADDITION THE HIGHEST POPS WILL BE FURTHER
EAST...WITH MANY LOCATIONS WEST OF A MCHENRY TO LA SALLE COUNTY
LINE WILL REMAIN DRY THROUGH MOST OF THE OVERNIGHT. BY DAYBREAK
PRECIP WILL INVADE THESE LOCATIONS.
BEACHLER
//PREV DISCUSSION...
334 PM CDT
...POWERFUL AUTUMN STORM TO LAMBASTE THE AREA WITH RAIN AND VERY
STRONG WINDS...
PRIMARY FORECAST CHALLENGE WILL OBVIOUSLY REVOLVE AROUND THE
DEVELOPING POWER-HOUSE AUTUMN STORM AND ITS IMPACTS THROUGH THE NEXT
COUPLE OF DAYS.
WATER VAPOR IMAGERY THIS AFTERNOON SHOWS A SERIES OF VORT MAXES
PIVOTING AROUND THE BASE OF AN AMPLIFYING TROUGH OVER THE
MISSISSIPPI VALLEY. POWERFUL 130KT+ 250MB JET IS DIGGING DOWN THE
BACKSIDE OF THIS TROUGH AND IS PROGGED TO LEAD TO SIGNIFICANT
DIGGING AND AMPLIFICATION. IN FACT...MODELS ARE SUGGESTING H5
HEIGHTS WILL DROP TO GREATER THAN 5 STANDARD DEVIATIONS BELOW
AVERAGE TONIGHT OVER THE LOWER MISSISSIPPI VALLEY WITH TROUGH
BECOMING NEGATIVELY TILTED WITH MID LEVEL CIRCULATION CLOSING OFF.
AN INTERESTING SCENARIO WILL TAKE PLACE THE NEXT 26 HOURS AS
SUBTROPICAL LOW OVER THE GULF OF MEXICO IS ABSORBED INTO THE
DEVELOPING MID-LATITUDE CYCLONE. THE MODELS ARE IN SURPRISINGLY GOOD
AGREEMENT IN HANDLING THIS COMPLEX INTERACTION WITH ONE SURFACE LOW
TRACKING UP THE EAST COAST...WHILE INTENSE SECONDARY SURFACE
CYCLOGENESIS TAKES PLACE OVER THE OHIO VALLEY WITH SURFACE LOW
DEEPENING TO SUB-990BM WEDNESDAY AS IT MOVES INTO LOWER MICHIGAN.
VERY INTENSE PRESSURE GRADIENT AROUND THIS LOW WILL RESULT IN A
QUICK RAMPING UP OF WIND TONIGHT AND PARTICULARLY WEDNESDAY. WIND
GUSTS WILL RISES INTO THE 30-40 MPH RANGE WEDNESDAY AFTERNOON AND
CONTINUE WEDNESDAY NIGHT...WITH THE EXCEPTION BEING NEAR THE LAKE
WHERE LACK OF FRICTION AND SOME WEAK INSTABILITY SHOULD ALLOW FOR
EVEN STRONGER WINDS NEAR THE IMMEDIATE LAKE SHORE. SUSTAINED WINDS
OF 30-40 MPH ARE LIKELY ALONG THE IMMEDIATE SHORE WITH GUSTS OF
50-60 MPH POSSIBLE...SO HAVE HOISTED A HIGH WIND WATCH FOR AREAS
NEAR THE LAKE. ITS POSSIBLE THAT INLAND WINDS MAY FLIRT WITH
ADVISORY CRITERIA FOR A TIME...BUT IT LOOKS MUCH MORE MARGINAL AND
HAVE OPTED TO HOLD OFF ON ANY HEADLINES AWAY FROM THE LAKE.
THE STRONG WINDS BLOWING DOWN THE FULL LENGTH OF THE LAKE WILL
RESULT IN VERY LARGE AND BATTERING WAVES ALONG BOTH THE ILLINOIS AND
INDIANA SHORELINE. IT DOES APPEAR AS THOUGH WINDS MAY BE A BIT
WEAKER THAN THE LATE SEPTEMBER STORM AND INSTABILITY NOT QUITE AS
STRONG WITH SOME WEAK WARM AIR ADVECTION WRAPPING COMPLETELY AROUND
THE STORM...HOWEVER THE FETCH WITH THIS STORM WILL RESULT IN THE
HIGHEST WAVES TAKING AIM ON THE ILLINOIS AND FAR NW INDIANA SHORE.
GIVEN THE POTENTIAL FOR 20FT+ WAVES...HAVE OPTED TO HOIST A LAKE
SHORE FLOOD WARNING FOR ALL OF OUR LAKE MICHIGAN SHORE. IN REALITY
WAVES AND THE RESULTANT FLOOD POTENTIAL OVER LAKE COUNTY ILLINOIS
AND NORTHERN COOK COUNTY MAY BE BE SOMEWHAT LESS...FOR THE SAKE OF
SIMPLICITY OPTED TO GO WITH A SINGLE HEADLINE EVERYWHERE. DURING THE
LATE SEPTEMBER STORM WAVES ALONG THE CHICAGO SHORE REACHED UP TO 17
FT...IF THE CURRENT WAVE MODEL FORECAST VERIFIES WE COULD SEE WAVES
ALONG THE CHICAGO SHORE 3-5FT LARGER RESULTING IN EVEN MORE
SIGNIFICANT SHORE LINE FLOODING.
OTHER STORY WITH THIS STORM WILL BE THE RAINFALL. DEFORMATION ZONE
WILL BEGIN TO DEVELOP TONIGHT OVER OUR SOUTHEAST CWA GRADUALLY
BUILDING NORTHWEST ACROSS THE AREA WEDNESDAY. PRIOR TO THE SYNOPTIC
SYSTEM'S RAIN ARRIVING WE COULD ACTUALLY SEE LAKE EFFECT SHOWERS
TONIGHT INTO WEDNESDAY MORNING OVER NORTHEAST ILLINOIS AND HAVE
NUDGED POPS UP ACCORDINGLY...THOUGH THE LAKE EFFECT SET UP IS NOT
EXTRAORDINARY. RAIN COVERAGE/INTENSITY SHOULD PEAK WEDNESDAY NIGHT
AS WELL DEVELOPED TROWAL WRAPS AROUND THE INTENSE CYCLONE. PWATS
NEARING AN INCH ALONG WITH STRONG SYNOPTIC SCALE FORCING COULD SET
THE STAGE FOR A BAND OF MODERATE TO RATHER HEAVY RAIN TO SET UP
ACROSS THE CWA...ESPECIALLY EASTERN PORTIONS. MODERATELY STEEP MID
LEVEL LAPSE RATES WRAPPING AROUND THE SYSTEM COULD EVEN RESULT IN A
LOW END THREAT OF SOME EMBEDDED THUNDER...THOUGH CHANCES LOOK
MINIMAL AND HAVE KEPT OUT OF THE FORECAST FOR NOW.
SYSTEM WILL QUICKLY PULL OUT THURSDAY WITH RAIN ENDING AND WIND
GRADUALLY SUBSIDING. WILL LIKELY TAKE SOME TIME FOR WAVES TO SUBSIDE
AND HAVE CARRIED THE CFW INTO THURSDAY/THURSDAY NIGHT TIME RANGE TO
GIVE WAVES SUFFICIENT TIME TO SUBSIDE.
CURRENTLY MODELS ARE SUGGESTING THAT SKIES WILL CLEAR OUT QUICKLY
WEDNESDAY NIGHT...HOWEVER AM A BIT LEARY ABOUT THIS AS GIVEN MODEL'S
TENDENCIES TO MOVE CLOSED LOWS OUT TOO QUICKLY. EVEN IF SKIES DO
CLEAR IT APPEARS AS THOUGH THERE WILL BE ENOUGH WIND TO KEEP THE
THREAT OF WIDESPREAD FROST LOW AND HAVE KEPT IT OUT OF THE GRIDS FOR
NOW. FRIDAY NIGHT MAY ACTUALLY POSE A GREATER THREAT FOR FROST/NEAR
FREEZE CONDITIONS IN OUTLYING AREAS AS SKIES WILL ALREADY BE CLEAR
AND WINDS FAIRLY LIGHT...BUT THIS THREAT WILL HINGE ON HOW QUICKLY
WARM AIR ADVECTION KICKS IN.
BEYOND THAT WEATHER PATTERN LOOKS FAIRLY QUIET WITH A RETURN TO NEAR
SEASONABLE CONDITIONS LIKELY OVER THE WEEKEND INTO EARLY NEXT WEEK.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 02Z...
* ON AND OFF PRECIP LATER TONIGHT...HEAVIER RAIN TOMORROW
* DOWNWARD CIG TRENDS
* DOWNWARD VIS TRENDS
* STRONGER WIND TRENDS
SHEA
//DISCUSSION...UPDATED 00Z...
AN ACTIVE DEGRADATION TO THE CONDITIONS IS SLOWLY UNDERWAY THIS
EVENING. DEEPENING LOW PRESSURE WILL CONTINUE TO WORK NORTH
THROUGH THE OHIO VALLEY OVERNIGHT. AS THIS AREA LIFTS NORTH...IT
WILL GIVE WAY TO SEVERAL SIGNIFICANT IMPACTS THAT INCLUDE STRONG
WINDS...IFR CIGS /WITH LIFR POTENTIAL INTO WEDS EVENING/ AS WELL
AS TIMING OF PRECIP.
IN THE SHORT TERM...ALL TERMINALS ARE SITTING VFR...BUT PATCHES OF
LAKE EFFECT SHOWERS ARE BEGINNING TO RIPPLE SOUTH AND WILL MOVE
ACROSS THE TERMINALS. FOR ORD AND MDW...SIDING ON THE PESSIMISTIC
SIDE AND PUT IN AN HOUR LONG TEMPO WITH CONDITIONS SIMILAR TO
EARLIER THIS EVENING WHERE VIS/CIGS DROPPED TO MVFR. NOT
ANTICIPATING ANYTHING PROLONGED BEFORE RETURNING TO VFR FOR THE
OVERNIGHT HOURS. BY DAWN SHOWER ACTIVITY SHOULD BEGIN TO BE ON THE
INCREASE...WITH OFF AND ON SHOWERS SEEN THROUGH THAT TIME. INTO
THE AFTERNOON HOURS AND ESPECIALLY OVERNIGHT...SHOWERS WILL
INCREASE IN INTENSITY. WITH THAT CIGS...AND VISIBILITY WILL DROP.
FORECAST GUIDANCE HAS SUGGESTED THAT CIGS COULD FALL INTO THE 005
OR LOWER RANGE INTO TOMORROW NIGHT...AND DID TREND TOWARDS THE
LOWER IFR SPECTRUM FOR THIS ISSUANCE.
AN EVER TIGHTENING PRESSURE GRADIENT AND INCREDIBLE PRESSURE FALLS
WILL ALLOW WINDS TO INCREASE OVERNIGHT. PEAK WIND GUSTS INTO THE
AFTERNOON AND EVENING HOURS TOMORROW WILL LIKELY TOP OUT OVER 35
KT AND PERSIST THROUGH THE END OF THE TAFOR.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* MEDIUM CONFIDENCE IN ARRIVAL OF PRECIP TIMING TOWARDS MORNING
* HIGH CONFIDENCE IN WIND FORECAST/STRONG WINDS
* MEDIUM CONFIDENCE ON VIS TRENDS W/ POTENTIAL TO IFR
* MEDIUM CONFIDENCE IN CIG TRENDS...LOW WITH HOW LOW THEY WILL GO
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...CHANCE OF SHOWERS...IFR POSSIBLE
FRIDAY THROUGH MONDAY...VFR
SHEA
&&
.MARINE...
252 PM CDT
NORTH TO NORTHEAST GALES DEVELOPING WEDNESDAY MORNING INCREASING
TO STORM FORCE ACROSS MUCH OF LAKE MICHIGAN LATE WEDNESDAY
AFTERNOON AND EVENING
LOW PRESSURE IS BEGINNING TO TAKE SHAPE ACROSS THE SOUTHEASTERN U.S.
AS AN UPPER TROUGH INTENSIFIES AND DIGS INTO THE MISSISSIPPI RIVER
VALLEY. LOW PRESSURE WILL CONSOLIDATE AND INTENSIFY AND MOVE
NORTH ACROSS THE TENNESSEE AND OHIO VALLEYS INTO WEDNESDAY
AFTERNOON. NORTH-NORTHWEST WINDS ACROSS THE LAKE THIS AFTERNOON
WILL TURN NORTH THEN NORTHEASTERLY THIS EVENING AND STEADILY
INCREASE IN SPEED. EXPECT THAT WINDS WILL REACH GALE FORCE
SOMETIME AROUND DAYBREAK ACROSS MUCH OF THE LAKE...ESPECIALLY
SOUTH. THE LOW WILL FURTHER STRENGTHEN TO AROUND 29.6 INCHES AND
APPROACH FT. WAYNE WEDNESDAY EVENING. AS THIS OCCURS...WINDS WILL
FURTHER STRENGTHEN TO STORM FORCE AROUND 50 KT ACROSS THE CENTRAL
AND SOUTHERN PORTIONS OF LAKE MICHIGAN...STARTING LATER WEDNESDAY
AFTERNOON. NORTHERN SECTIONS WILL INCREASE TO HIGH END GALES AND AM
STILL WATCHING POTENTIAL FOR STORM FORCE GUSTS TO 50 KT.
UNCERTAINTY STILL SURROUNDS THIS SO WILL MOVE AHEAD WITH A GALE
WARNING BUT AN UPGRADE MAY BE NEEDED FOR WEDNESDAY EVENING/NIGHT.
ALSO WATCHING FOR GUST POTENTIAL IN THE 55-60 KT RANGE SOUTH...BUT
WITH THE AIRMASS OVER THE LAKE NOT BEING TERRIBLY COLD RELATIVE TO
THE LAKE WATER MIXING MAY BE LIMITED. DESPITE THIS FEEL THAT 50 KT
WILL BE ACHIEVED GIVEN WINDS INCREASING TO AROUND 50 KT IN THE
FIRST FEW HUNDRED FEET ABOVE LAKE LEVEL...IT MAY BE DIFFICULT TO
SEE GUSTS HIGHER THAN THAT HOWEVER. WILL CONTINUE TO MONITOR. PEAK
GUSTS ARE EXPECTED WEDNESDAY EVENING AND NIGHT.
THE LOW WILL BEGIN TO WEAKEN AND TURN NORTHEAST THURSDAY ALLOWING
WINDS TO EASE THROUGH THE DAY THOUGH GALE FORCE IS EXPECTED
THROUGH THE AFTERNOON. HIGH PRESSURE WILL THEN ARRIVE FRIDAY AND
FRIDAY
NIGHT RESULTING IN MUCH QUIETER CONDITIONS. A WEAK FRONT MAY CROSS
THE LAKE SOMETIME SUNDAY WITH A STRONGER SYSTEM AFFECTING THE AREA
EARLY NEXT WEEK.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD WARNING...ILZ006-ILZ014...3 PM WEDNESDAY TO 4 PM
THURSDAY.
HIGH WIND WATCH...ILZ006-ILZ014...3 PM WEDNESDAY TO 10 AM
THURSDAY.
IN...HIGH WIND WATCH...INZ001-INZ002...3 PM WEDNESDAY TO 10 AM
THURSDAY.
LAKESHORE FLOOD WARNING...INZ001-INZ002...3 PM WEDNESDAY TO 9 PM
THURSDAY.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...5 AM
WEDNESDAY TO 3 PM WEDNESDAY.
STORM WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-
LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 PM WEDNESDAY TO 3 PM
THURSDAY.
GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...10 AM
WEDNESDAY TO 10 PM THURSDAY.
GALE WARNING...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...1 AM
WEDNESDAY TO 3 PM WEDNESDAY.
&&
$$
