232 PM CST
SEVERAL SYSTEMS WILL AFFECT THE AREA THROUGH WEDNESDAY BRINGING MILD
WEATHER IN THE SHORT TERM FOLLOWED BY A NOTICEABLE COOL DOWN BY MID
WEEK. PERIODS OF RAIN WILL ALSO BECOME MORE LIKELY BEFORE THINGS DRY
OUT LATER IN THE WEEK. EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS
UPPER LEVEL RIDGING ARCHING FROM PENNSYLVANIA BACK INTO SOUTHWESTERN
HUDSON BAY. A BROAD LONGWAVE TROUGH IS POSITIONED TO THE WEST FROM
SOUTHWEST AND SOUTH CENTRAL CANADA INTO THE WESTERN AND CENTRAL U.S.
WITH A SERIES OF EMBEDDED LOW CIRCULATIONS TRANSLATING THROUGH IT.
THE FIRST IS LIFTING NORTHWARD INTO CENTRAL MANITOBA AND WESTERN
ONTARIO WITH AN ASSOCIATED DEEP SURFACE LOW MOVING NORTHEASTWARD
FROM LAKES WINNIPEG AND MANITOBA. THE SECOND SIGNIFICANT CIRCULATION
IS DIGGING SOUTHEASTWARD ACROSS SOUTHERN CALIFORNIA AND NEVADA AND
WILL BRING A SURFACE LOW ACROSS THE FORECAST AREA LATER TUESDAY.
TONIGHT...THE MANITOBA SURFACE LOW WILL CONTINUE TO TRACK
NORTHEASTWARD INTO NW ONTARIO THIS EVENING AND WEAKEN. THE PRESSURE
GRADIENT WILL GRADUALLY WEAKEN ACROSS THE LOCAL AREA INTO THE
EVENING ALLOWING WINDS TO DIMINISH WITH GUSTS DROPPING OFF WITH
SUNSET. A WEAKENING COLD FRONTAL BOUNDARY WILL MOVE EASTWARD INTO
THE AREA THIS EVENING BUT WITH THE PARENT SURFACE LOW LIFTING
NORTHEASTWARD THE FRONT WILL MAKE SLOW PROGRESS AND EVENTUALLY STALL
OUT FROM SOUTHERN LAKE MICHIGAN SOUTHWESTWARD INTO FAR SOUTHEAST
IOWA OR NORTHEAST MISSOURI BY MONDAY MORNING. LITTLE IF ANY
RAIN/SPRINKLES ARE EXPECTED AS THE FRONT ENTERS THE AREA THIS
EVENING WITH DEEP LAYER MOISTURE STILL LACKING SOMEWHAT. A BETTER
PUSH OF GULF MOISTURE WILL POOL ALONG THE FRONT LATE TONIGHT AND
MONDAY HOWEVER. POPS WILL BE TRICKY LATER TONIGHT BUT AT THIS POINT
THE BEST CHANCES ARE EXPECTED TO BE CONFINED TO THE FAR SOUTHEASTERN
CWA OR SOUTH OF A LINE FROM GARY TO PONTIAC THOUGH THIS MAY BE TOO
FAR NORTHWEST.
MONDAY THROUGH TUESDAY NIGHT...THE WESTERN UPPER TROUGH WILL MAKE
ITS WAY INTO THE FOUR CORNERS MONDAY AFTERNOON WITH HEIGHT FALLS OUT
AHEAD OF IT SPAWNING SURFACE CYCLOGENESIS ACROSS THE TEXAS
PANHANDLE. AN INVERTED TROUGH WILL ALSO DEVELOP ALONG THE STALLED
COOL FRONTAL BOUNDARY AND EXTEND FROM THE DEVELOPING LOW
NORTHEASTWARD ACROSS SOUTHERN LAKE MICHIGAN BY MONDAY NIGHT.
SOUTHEASTERN AREAS WILL CONTINUE TO NEED AT LEAST LOW CHANCE POPS
MONDAY MORNING WITH CHANCES INCREASING THROUGH THE AFTERNOON AND
ESPECIALLY DURING THE EVENING AS ISENTROPIC ASCENT OVER THE FRONT
INCREASES AMID A 50+ KT LOW LEVEL JET AND THE MID LEVEL BAROCLINIC
ZONE TIGHTENS AS FRONTOGENESIS INCREASES. THE SURFACE LOW REMAIN
SOMEWHAT BROAD BUT MOVE NORTHEASTWARD TUESDAY WITH THE INVERTED
TROUGH REMAINING PARKED ACROSS THE AREA FROM NE TO SW. AS THE LOW
LIFTS NORTHEASTWARD RAIN CHANCES WILL SPREAD NORTHWARD ACROSS THE
REST OF THE AREA MONDAY EVENING AND MONDAY NIGHT. THE QUESTION THAT
REMAINS IS HOW FAR WEST THE LOW WILL TRACK AND THEREFORE HOW DOES
THE INVERTED TROUGH SHIFT FROM TUESDAY INTO TUESDAY NIGHT. ECMWF
REMAINS THE OUTLIER BEING DEEPER WITH THE UPPER TROUGH AND THEREFORE
SLOWER AND FURTHER WEST WITH THE SURFACE LOW WHILE THE GFS AND NAM
REMAIN FASTER AND FURTHER EAST. GFS AND SREF ENSEMBLE MEANS ARE MORE
IN LINE WITH THE NAM AND THE GFS IN TERMS OF TAKING THE LOW RIGHT
OVER THE AREA AND ACROSS LAKE MICHIGAN. WILL MAKE LITTLE CHANGE TO
THE FORECAST FROM MONDAY NIGHT THROUGH TUESDAY NIGHT IN TERMS OF
POPS WITH THE BEST CHANCES ALONG AND WEST OF INTERSTATE 57 THOUGH
AREAS TO THE EAST WILL CONTINUE TO SEE CHANCE AND LIKELY POPS DURING
THIS TIME. A FURTHER WESTWARD TRACK WOULD RESULT IN SOMEWHAT LOWER
POPS FOR THESE AREAS. HEAVY RAINFALL IS A CONCERN WITH PRECIPITABLE
WATER VALUES IN THE 1.25-1.5 INCH RANGE. ADD TO THIS THE THREAT FOR
THUNDERSTORMS AS A RIBBON OF INSTABILITY DEVELOPS EARLY TUESDAY AND
REMAINS IN PLACE INTO TUESDAY EVENING. THERE IS THE POTENTIAL FOR MUCH OF
THE CENTRAL AND WESTERN PART OF THE AREA OR WEST OF ROUGHLY
INTERSTATE 57 TO SEE 1-2 INCHES OF RAIN BETWEEN MONDAY AND
WEDNESDAY...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. WILL NEED TO
MONITOR POTENTIAL FOR SOME STRONGER STORMS ACROSS THE SOUTHERN AND
SOUTHEASTERN CWA IF INSTABILITY CAN INCREASE AND STRONG LOW LEVEL
WINDS CAN BE BROUGHT TO THE SURFACE.
WEDNESDAY THROUGH SATURDAY...THE SURFACE LOW WILL CROSS THE AREA
TUESDAY NIGHT/EARLY WEDNESDAY BRINGING A SHARP COLD FRONT ACROSS THE
AREA WEDNESDAY MORNING. THE UPPER LOW WILL LIFT TO THE NORTHWEST OF
THE AREA WITH A PUNCH OF DRIER AIR EXPECTED BEHIND THE FRONT BUT
ANOTHER AREA OF PRECIPITATION WILL PROBABLY DEVELOP JUST AHEAD OF
THE UPPER TROUGH. AREAS NORTH OF INTERSTATE 80 LOOK TO STAND THE
BEST CHANCE FOR PRECIP BEHIND THE FRONT. H85 TEMPS WILL TUMBLE TO -2
OR -3 C BY WEDNESDAY EVENING AND PROBABLY FALL ANOTHER DEGREE OR TWO
BY THURSDAY MORNING. A MUCH DRIER ATMOSPHERE LOOKS TO BE IN PLACE BY
WEDNESDAY AFTERNOON BUT THE CYCLONIC FLOW MAY SUPPORT SOME PRECIP
DEVELOPMENT...WHICH IF IT DOES OCCUR...WOULD PROBABLY BE A MIX OF
RAIN AND SNOW. HOWEVER...AT THIS POINT IT LOOKS LIKE THIS WOULD BE A
SLIM CHANCE. ASSUMING THE SYSTEM DOES NOT SLOW TOO MUCH THEN HIGHS
WEDNESDAY WOULD PROBABLY BE IN THE LOW 50S AT BEST DURING THE
MORNING AND PROBABLY FALL BACK INTO THE 40S DURING THE AFTERNOON
WITH HIGHS IN THE 40S THURSDAY.
HIGH PRESSURE WILL CREST THE AREA THURSDAY NIGHT WITH WARM ADVECTION
IN SOUTHERLY FLOW RETURNING FRIDAY LEADING TO MODERATING TEMPS. MUCH
OF THE WEEKEND MAY END UP DRY WITH LOW PRESSURE DEVELOPING TO THE
SOUTH AND WEST AT SOME POINT LATE IN THE WEEKEND OR EARLY NEXT WEEK
WITH LITTLE MODEL AGREEMENT BY THIS TIME.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* GUSTY SOUTHERLY WINDS THROUGH EARLY EVENING.
* MVFR CIGS FROM EARLY EVENING THROUGH MONDAY MORNING.
* CHANCE OF SHOWERS MONDAY AFTERNOON. CMS
//DISCUSSION...UPDATED 18Z...
STRONG SOUTHERLY WINDS WILL GRADUALLY BEGIN TO RELAX THIS
AFTERNOON...AS LOW PRESSURE OVER SOUTHERN MANITOBA CONTINUES TO
LIFT NORTHEAST. EXPECT PREVAILING GUSTS IN THE 25-30KT RANGE...
WITH SOME HIGHER GUSTS POSSIBLE OVER THE NEXT FEW HRS. GUSTS
SHOULD DIMINISH INTO THE 20KT RANGE WITH SUNSET THOUGH SPEEDS
STILL IN THE 10-15KT RANGE FOR MOST OF THE EVENING...AS THEY
SLOWLY TURN MORE SOUTHWESTERLY. A TRAILING COLD FRONT/WIND SHIFT
WITH THIS SYSTEM WILL STALL ACROSS THE AREA OVERNIGHT INTO MONDAY
MORNING. SOUTHERLY WINDS SHOULD BECOME LIGHT BY MORNING AND EVEN
LIGHT/VRB OR CALM BY MID/LATE MONDAY MORNING.
A LARGE AREA OF BKN/OVC CIGS EXTENDS FROM THE UPPER MIDWEST...
SOUTH ACROSS THE AREA AND INTO THE ARKLATEX REGION. CIGS CONTINUE
TO LOWER INTO THE 3-4KFT RANGE...THOUGH POCKETS/BREAKS OF MID
CLOUDS ALSO NOTED. EXPECT CIGS TO REMAIN VFR THROUGH SUNSET...WITH
THE EXCEPTION OF RFD WHERE MVFR CIGS ARE ALREADY PRESENT. BUT AS
THE ABOVE MENTIONED FRONT STALLS...LOW LEVEL MOISTURE IS EXPECTED
TO LIFT NORTH ACROSS THE AREA...ALONG AND AHEAD OF THIS FRONT.
THUS...EXPECT CIGS TO LOWER INTO HIGH MVFR...2-3KFT...THIS EVENING
AND REMAIN THERE INTO MONDAY MORNING. WILL NEED TO MONITOR TRENDS
FOR SPECIFIC TIMING AND HEIGHTS.
AS THE NEXT STORM SYSTEM DEVELOPS OVER THE SOUTHERN PLAINS TONIGHT
AND MONDAY...A STATIONARY FRONT WILL SLOWLY BEGIN TO LIFT NORTH
MONDAY AFTERNOON INTO MONDAY NIGHT...COMBINED WITH THE INCREASING
LOW LEVEL MOISTURE...A FEW SHOWERS ARE POSSIBLE MONDAY AFTERNOON
ESPECIALLY SOUTH OF I-80 BUT COULD GET AS FAR NORTH AS MDW/GYY
AFTER 18Z...AFTER THE END OF THIS PERIOD...THUS HAVE MAINTAINED
DRY CONDITIONS. CMS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE REGARDING WIND SPEEDS/GUSTS.
* MEDIUM CONFIDENCE CIGS WILL LOWER INTO HIGH MVFR THIS EVENING
AND CONTINUE INTO MONDAY MORNING...LOW CONFIDENCE ON TIMING.
* LOW CONFIDENCE REGARDING SHOWERS MONDAY AFTERNOON. CMS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...VFR. CHC SHRA ISO TSRA W/PATCHY MVFR CIGS.
TUESDAY...MVFR. SHRA/ISO TSRA W/PATCHY MVFR CIGS.
WEDNESDAY...MVFR TRENDING VFR. THEN RA BECOMING MIXED WITH SN LATE.
THURSDAY...MVFR WITH WINTRY MIX EARLY THEN VFR AND DRY.
FRIDAY...VFR. SLIGHT CHC SHRA.
SATURDAY...VFR.
BEACHLER
&&
.MARINE...
417 AM CST
TROUGH OF LOW PRESSURE CENTERED OVER THE DAKOTAS THIS MORNING WILL
CONTINUE TO STRENGTHEN AS IT SLIDES NORTHEAST INTO SOUTHWEST
ONTARIO. TO THE EAST OF THIS SYSTEM THE PRESSURE GRADIENT IS
EXPECTED TO TIGHTEN CONSIDERABLY TODAY...RESULTING IN GUSTY WINDS
OVER LAKE MICHIGAN THROUGH TONIGHT. IT APPEARS LIKELY THAT GALE
CRITERIA WILL BE ACHIEVED...HOWEVER THE PRECISE VELOCITY AND TIMING
APPEAR TO BE A CHALLENGE. GUIDANCE HAS CONTINUED TO INDICATE THAT
JUST BEFORE DAYBREAK TODAY WINDS OVER THE LAKE WILL BE GUSTING TO
AROUND GALE CRITERIA. UNFORTUNATELY THIS MAY TAKE SLIGHTLY LONGER TO
MATERIALIZE UNTIL MID MORNING. THE SECOND CHALLENGE IS THE ABUNDANCE
OF CLOUD COVER OVER THE WESTERN GREAT LAKES. NONETHELESS JUST OFF OF
THE DECK ARND 2KFT AGL...WINDS TO 50KT HAVE BEEN OBSERVED BASED ON
RADAR DATA. THUS VERY WINDY CONDITIONS HAVE DEVELOPED ALREADY...THEY
JUST HAVE YET TO HAVE BEEN REALIZED OVER THE MARINE SFC. THIS MAY
LIMIT THE POTENCY OF MIXING FOR THIS AFTERNOON OVER LAKE
MICHIGAN...AND RESULT IN MUCH LOWER WIND GUSTS. WHILE SUB-GALE
CRITERIA IS POSSIBLE...CONFIDENCE IN REMOVING THE HEADLINES IS VERY
LOW. THUS WILL CONTINUE TO ADVERTISE GALES FOR TODAY.
PRESSURE GRADIENT QUICKLY SLACKENS TONIGHT AS THE LOW PRESSURE
QUICKLY LIFTS NORTHEAST TOWARDS HUDSON BAY. AS THIS OCCURS A RIDGE
OF HIGH PRESSURE IS EXPECTED TO BUILD IN FROM THE WEST ACROSS THE
WESTERN GREAT LAKES. A SLUGGISH FRONTAL BOUNDARY WILL EXIST JUST TO
THE SOUTH OF LAKE MICHIGAN MONDAY AS YET ANOTHER LOW PRESSURE SYSTEM
DEVELOPS OVER THE SOUTHERN PLAINS. THIS SECOND LOW PRESSURE SYSTEM
WILL THEN DEEPEN AND LIFT NORTHEAST TOWARDS THE GREAT LAKES REGION
TUESDAY. THE PRESSURE GRADIENT IS ONCE AGAIN EXPECTED TO
INCREASE...AND POSSIBLY PRODUCE SMALL CRAFT ADVISORY CONDITIONS FOR
THE ILLINOIS/INDIANA NEARSHORE WATERS THROUGH WEDNESDAY MORNING.
WHILE IT IS CONCEIVABLE THAT THE WARMER AIR ADVECTING OVER THE
COOLER LAKE MAY PRODUCE A STABLE ENVIRONMENT AND INHIBIT WAVE
GROWTH...AT THIS TIME CONFIDENCE IS VERY LOW THAT THIS WILL OCCUR.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...NEARSHORE WATERS UNTIL 4
PM SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 3 AM MONDAY.
GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 PM SUNDAY.
&&
$$
