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 08Z...
* STRONG WINDS APPROACHING AND POSSIBLY SURPASSING 40 KTS.
* CONDITIONS DROPPING TO IFR AND POSSIBILITY LIFR. BMD
//DISCUSSION...UPDATED 06Z...
A STRONG FALL STORM WILL IMPACT THE CHICAGO AND ROCKFORD TERMINALS
THROUGH THE DAY AND INTO THE NIGHT WEDNESDAY...WITH STRONG WINDS
AND IFR/LIFR CONDITIONS EXPECTED ALONG WITH PERIODS OF MODERATE TO
HEAVY RAIN. AN ELONGATED AREA OF LOW PRESSURE OVER THE
SOUTHEASTERN UNITED STATES WILL CONTINUE TO DEVELOP THROUGH THE
DAY. STRONG PRESSURE FALLS OVER THE UPPER OHIO VALLEY WILL
INTENSIFY THROUGH THE MORNING AND AFTERNOON AS SURFACE
CYCLOGENESIS OCCURS IN RESPONSE TO VIGOROUS UPPER LEVEL SYSTEM.
STRONG PRESSURE FALLS IN ADDITION TO A TIGHTENING PRESSURE
GRADIENT WILL CAUSE WINDS TO INTENSIFY ACROSS THE UPPER
MIDWEST...WITH 50 KT+ WINDS EXPECTED OVER LAKE MICHIGAN POSSIBLY
IMPACTING AREAS RIGHT ALONG THE LAKESHORE SUCH AS GYY. WINDS WILL
DROP OFF AWAY FROM THE LAKE...BUT STILL EXPECT GUSTS TO INCREASE
WELL INTO THE 30KT RANGE BY LATE MORNING. NNE WINDS WILL BACK TO
THE NNW BY THIS EVENING AS THE LOW GRADUALLY LIFTS NORTH THROUGH
THE DAY.
IN ADDITION TO THE WINDS...EXPECT CIG/VIS CONDITIONS TO DETERIORATE
THROUGH THE DAY AS WELL. FOR THE REMAINDER OF TONIGHT...SOME SHOWERS
ARE GENERATING OFF OF LAKE MICHIGAN...AND AREA OCCASIONALLY
DROPPING CIGS TO HIGH END MVFR...BUT OTHERWISE EXPECT PREVAILING VFR
CONDITIONS THROUGH EARLY THIS MORNING. THAT SAID...A DOWNWARD TREND
IS EXPECTED AS 500MB HEIGHT FALLS OVERSPREAD THE AREA AND THE COLUMN
SATURATES. EXACT TIMING IS A LITTLE UNCERTAIN...BUT EXPECT SHOWERY
PRECIP THIS MORNING TO EVENTUALLY GIVE WAY TO MORE WIDESPREAD AND
STEADY RAINFALL THIS AFTERNOON AS DEFORMATION ZONE MOVES OVERHEAD
FROM THE SOUTHEAST. CONDITIONS ARE EXPECTED TO BOTTOM OUT LATE
TONIGHT AS THE LOW CENTER RETROGRADES SOMEWHAT INTO NORTHERN
INDIANA. A MIX OF GUIDANCE SUGGESTS THAT CONDITIONS SHOULD DROP TO
AT LEAST IFR...BUT LIFR CONDS NOT OUT OF THE REALM OF POSSIBILITY.
IMPROVEMENT IS EXPECTED BEYOND THE CURRENT TAF PERIOD...LATE
THURSDAY MORNING OR THURSDAY AFTERNOON. BMD
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* MEDIUM CONFIDENCE IN WIND SPEED...HIGH CONFIDENCE IN DIRECTION.
* MEDIUM CONFIDENCE IN CIGS DROPPING TO IFR...LOW CONFIDENCE IN
TIMING. BMD
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...CHANCE OF SHOWERS...IFR POSSIBLE
FRIDAY THROUGH MONDAY...VFR
SHEA
&&
.MARINE...
300 AM CDT
STORM FORCE WINDS NOW EXPECTED ACROSS ALL OF LAKE MICHIGAN BY
LATE AFTERNOON/EARLY THIS EVENING.
ONLY SIGNIFICANT CHANGE THIS MORNING IS TO UPGRADE THE NORTHERN
THIRD OR SO OF LAKE MICHIGAN FROM A GALE WARNING TO A STORM WARNING.
AN ELONGATED AREA OF LOW PRESSURE EXTENDS FROM SOUTHERN GEORGIA
NORTH INTO SOUTHERN OHIO. THIS LOW WILL CONSOLIDATE DURING THE DAY
AS IT DEEPENS...REACHING NORTHWEST OHIO/FAR NORTHEAST INDIANA LATE
THIS EVENING. A LARGE RIDGE OF HIGH PRESSURE EXTENDING FROM HUDSON
BAY TO TEXAS WILL SLOWLY MOVE EAST TODAY AND TONIGHT. THE GRADIENT
WILL TIGHTEN RAPIDLY BETWEEN THESE TWO FEATURES THIS AFTERNOON INTO
THIS EVENING. SO EXPECTING A PERIOD OF STEADILY INCREASING GALES
FROM NOW THROUGH EARLY AFTERNOON...FROM SOUTH TO NORTH ACROSS THE
LAKE. THEN STORM FORCE WINDS DEVELOPING BY LATE AFTERNOON ACROSS
THE SOUTH...AND SPREADING NORTH THROUGH THE EVENING. WHILE THE LOW
WILL BEGIN TO WEAKEN AS IT LIFTS NORTHEAST ACROSS THE EASTERN GREAT
LAKES THURSDAY...AND THUS EXPECT STORM FORCE WINDS TO END BY EARLY
THURSDAY AFTERNOON...THE GRADIENT WILL STILL REMAIN QUITE STRONG
AND EXPECT GALES TO PERSIST WELL INTO THURSDAY EVENING BEFORE
FINALLY DIMINISHING TO 30 KTS OR LESS LATE THURSDAY NIGHT. A RIDGE
OF HIGH PRESSURE WILL MOVE ACROSS THE LAKE FRIDAY...WITH A WEAK
TROUGH/COLD FRONT MOVING ACROSS THE WESTERN LAKES SATURDAY. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ006-ILZ014...3 PM WEDNESDAY TO 10 AM
THURSDAY.
LAKESHORE FLOOD WARNING...ILZ006-ILZ014...3 PM WEDNESDAY TO 4 PM
THURSDAY.
WIND ADVISORY...ILZ005-ILZ012-ILZ013-ILZ020-ILZ021-ILZ022-ILZ023-
ILZ032-ILZ033-ILZ039...3 PM WEDNESDAY TO 10 AM THURSDAY.
IN...HIGH WIND WARNING...INZ001-INZ002...3 PM WEDNESDAY TO 10 AM
THURSDAY.
LAKESHORE FLOOD WARNING...INZ001-INZ002...3 PM WEDNESDAY TO 9 PM
THURSDAY.
WIND ADVISORY...INZ010-INZ011-INZ019...3 PM WEDNESDAY TO 10 AM
THURSDAY.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-
LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 PM WEDNESDAY.
STORM WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
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 3 PM WEDNESDAY.
&&
$$
