316 PM CST
THE NEXT WEATHER MAKER FOR THE AREA IS BEGINNING TO TAKE SHAPE THIS
AFTERNOON. WATER VAPOR IMAGERY SHOWS UPPER RIDGING HOLDING IN PLACE
OVER THE SOUTHEAST AND MID-ATLANTIC STATES WITH WITH AN UPPER LOW
LIFTING NORTHEAST ACROSS NORTHERN QUEBEC ALONG THE WESTERN PERIPHERY
OF THE RIDGE. THE MAIN FEATURE OF CONCERN IS AN UPPER TROUGH
SPINNING OVER THE FOUR CORNERS AND BEGINNING TO TURN NORTHEASTWARD.
AT THE SURFACE...A STATIONARY FRONTAL BOUNDARY...WHICH DRIFTED INTO
THE AREA OVERNIGHT...EXTENDS FROM NORTHWEST INDIANA BACK TOWARDS ST.
LOUIS AND ON TOWARDS THE DEVELOPING LOW PRESSURE OVER THE TEXAS
PANHANDLE. DEEPER MOISTURE CONTINUES TO STREAM NORTHEASTWARD IN THE
FAST SOUTHWESTERLY FLOW THAT HAS DEVELOPED AHEAD OF THE TROUGH. IN
ADDITION A SERIES OF VORT MAXES/LOW AMPLITUDE SHORTWAVES ARE MOVING
NORTHEASTWARD AS WELL. AS A RESULT...BANDS OF RAIN CONTINUE TO
STREAM NORTHEASTWARD IN CONJUNCTION WITH THE TRANSPORT OF MOISTURE
AND THE LOCATION OF THE SURFACE BOUNDARY WITH ONE NOW SHIFTING OFF
TO THE EAST AND ANOTHER TAKING SHAPE ACROSS MISSOURI AND POINTS
SOUTHWEST.
TONIGHT THROUGH TUESDAY MORNING...THE UPPER TROUGH WILL CONTINUE TO
PUSH EASTWARD ACROSS THE ROCKIES TONIGHT WITH HEIGHT FALLS SPREADING
INTO KANSAS...OKLAHOMA...AND NORTHERN TEXAS ALLOWING FURTHER
DEVELOPMENT OF THE SURFACE LOW WHICH SHOULD CONSOLIDATE OVER THE
EASTERN KANSAS/OKLAHOMA BORDER AREA BY MIDDAY TUESDAY. AS THE LOW
DEVELOPS AN INVERTED TROUGH WILL SHARPEN ALONG THE OLD COOL FRONTAL
BOUNDARY ACROSS THE AREA. THIS WILL HELP THE BOUNDARY TO PUSH
NORTHWESTWARD AND LIKELY BISECT THE AREA FROM NORTHEAST TO SOUTHWEST
BY LATE TUESDAY. MID LEVEL FRONTOGENESIS CURRENTLY EXTENDING FROM
NORTHERN INDIANA INTO SOUTHEASTERN MISSOURI WILL PULL OFF TO THE
EAST BY EVENING WITH ANOTHER AREA EXPECTED TO DEVELOP FROM MISSOURI
INTO EASTERN IOWA AND OVER INTO NORTHWEST INDIANA IN CONJUNCTION
WITH SHARP ISENTROPIC ASCENT. THE CURRENT AREA OF RAIN OVER THE
SOUTHEASTERN CWA WILL CONTINUE TO LIFT OFF TO THE NORTHEAST AND
THERE SHOULD BE A LULL IN THE PRECIP THROUGH EARLY EVENING. ANOTHER
SHIELD OF RAIN WILL THEN SPREAD NORTHEASTWARD ACROSS MUCH OF THE
AREA LATE THIS EVENING OR EARLY TONIGHT AND CONTINUE THROUGH TUESDAY
MORNING THANKS TO THE AFOREMENTIONED FORCING.
TUESDAY AFTERNOON THROUGH THURSDAY...LATEST MODEL GUIDANCE HAS COME
INTO BETTER AGREEMENT WITH THE TRACK AND SPEED OF THE LOW...WITH THE
LATEST GUIDANCE SOLUTION BASICALLY A MIDDLE GROUND BETWEEN THE
EARLIER GFS WHICH HAD BEEN FASTER AND FARTHER EAST AND THE EARLIER
ECMWF WHICH HAD BEEN SLOWER AND FURTHER WEST. THE SURFACE LOW WILL
CONTINUE TO MARCH NORTHEASTWARD INTO WEST CENTRAL ILLINOIS TUESDAY
AFTERNOON AS THE MAIN UPPER LOW LIFTS NORTHEASTWARD FROM
CENTRAL/EASTERN KANSAS. THE INITIAL ROUND OF FORCING WILL LIFT TO
THE NORTHEAST BY EARLY TUESDAY AFTERNOON. THIS MAY RESULT IN A LULL
IN THE PRECIP ACTIVITY FOR AT LEAST SOME OF THE AFTERNOON. ANOTHER
ROUND OF FORCING THEN ARRIVES WITH THE ARRIVAL OF THE LOW AND
ASSOCIATED COLD FRONT TUESDAY EVENING INTO TUESDAY NIGHT. BEST
CHANCES FOR EMBEDDED THUNDER ARRIVE TUESDAY AND CONTINUE INTO
TUESDAY NIGHT. RIGHT NOW IT LOOKS TO REMAIN MAINLY ELEVATED THOUGH
WILL NEED TO WATCH FOR POTENTIAL FOR SOME WIND GUSTS TO MAKE IT TO
THE SURFACE. OTHER CONCERN IS HEAVY RAIN POTENTIAL INTO WEDNESDAY WITH
MUCH OF THE CENTRAL AND WESTERN PART OF THE AREA EXPECTED TO SEE 1
TO 2 INCHES WITH SOME POTENTIAL FOR UPWARDS OF 2.5 INCHES WEST OF
A LINE FROM ROUGHLY WAUKEGAN TO LASALLE.
THE LOW SHOULD PASS OVER THE ROCKFORD AREA THEN CONTINUE ACROSS
CENTRAL LAKE MICHIGAN WEDNESDAY MORNING WHICH WILL DRAG THE RATHER
STRONG COLD FRONT ACROSS THE AREA WEDNESDAY MORNING. WINDS WILL
SHIFT FROM SOUTH TO WEST WITH THE FRONTAL PASSAGE WITH A FURTHER
SHIFT TO WEST-NORTHWEST DURING THE AFTERNOON. H85 TEMPS WILL
TUMBLE FROM AROUND +10 C TO AROUND 0 C BY MIDDAY THEN TO AROUND -4
C BY WEDNESDAY EVENING. HAVE INDICATED MAX TEMPS WEDNESDAY MORNING
WIT A COOLING TREND INTO AN THROUGH THE 40S WEDNESDAY AFTERNOON AS
COLD ADVECTION TAKES OVER. STILL ANTICIPATE THAT A DRY SLOT WILL
WRAP AHEAD OF THE UPPER LOW BEHIND THE COLD FRONT SO PRECIP MAY
CUTOFF MORE QUICKLY THAN THE FORECAST CURRENTLY INDICATES.
DEFORMATION ZONE PRECIP LOOKS TO FOCUS TO THE NORTH BUT WILL CARRY
MINIMAL POPS DURING THE AFTERNOON FOR THIS. ANOTHER UPPER TROUGH
WILL CROSS THE AREA THURSDAY AND WILL NEED TO MONITOR FOR THE
POTENTIAL FOR SCATTERED SHOWER DEVELOPMENT.
MDB
FRIDAY THROUGH THE WEEKEND...
VOLATILITY IN THE FORECAST WILL BEGIN TO RAMP UP TOWARDS THE WEEKEND
AND THERE WILL LIKELY BE CHANGES TO THE WEEKEND FORECAST OVER THE
COMING SHIFTS. FORECAST GUIDANCE HAS BEEN TRYING TO FIGURE OUT WHAT
TO DO WITH A WAVE THAT SHOULD COME RIPPLING THROUGH THE
NORTHWESTERLY FLOW THROUGH THE WEEKEND. THIS ULTIMATELY HAS PROVED
TO YIELD A LOWER CONFIDENCE EXTENDED FORECAST AS FROM EACH MODEL RUN
TO MODEL RUN... THERE HAVE BEEN LARGE DIFFERENCES AND LITTLE
CONTINUITY. WHILE THE BEST CHANCES APPEAR TO BE TOWARDS SUNDAY
NIGHT...THE EC IS MUCH MORE BULLISH WITH QPF TOTALS ACROSS THE AREA
AS A SURFACE LOW TRACKS ACROSS IOWA AND INTO MINNESOTA. MEANWHILE
THE GFS IS JUST PAINTING A TRACE TO MAYBE A FEW HUNDREDTHS OF AN
INCH OF QPF AS THE SURFACE FEATURE IS GENERALLY 2-300 MILES WEST OF
WHERE THE EC PROGS ITS MOVEMENT...BUT THE GFS HAS SHIFTED THE LOW
FROM ACROSS LAKE HURON THREE RUNS AGO...TO MINNESOTA IN THE PREVIOUS
RUN...TO ACROSS NORTH DAKOTA WITH THIS RUN. OTHERWISE...SOUTHWEST
FLOW WILL RETURN TO THE AREA AND TEMPERATURES WILL BEGIN TO REBOUND
INTO THE WEEKEND FROM THEIR MIDWEEK COOL DOWN.
SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* MVFR CIGS AND VSBYS WITH PERIODS IFR CIGS AND VSBYS MUCH OF DAY.
* PSBL ISOLD TS EMBEDDED IN LARGE RAIN AREA.
* WIND DIR AND SPEED AS WMFNT CONTS TO LIFT SLOWLY N ACROSS NW IND
AND INTO NE IL WHILE SFC WAVE MOVS FM NE MO ALONG BOUNDARY TO
NE IL DURG THE DAY.
//DISCUSSION...UPDATED 06Z...
LOW PRESSURE CONTINUES TO ORGANIZE ACROSS THE SOUTHERN PLAINS WITH
A WARM FRONT EXTENDING NORTHEAST INTO CENTRAL IL. MOIST AIR
OVERRIDING THIS WILL CONTINUE TO PROMOTE WIDESPREAD
RAIN...SPREADING NORTH TO ORD AND RFD EARLY IN THE OVERNIGHT
PERIOD. WITHIN THE RAIN ITSELF...MVFR VISIBILITY IS LIKELY AND
TEMPORARY IFR IS PROBABLE. AT THE SAME TIME...FOG/MIST AND DRIZZLE
AROUND THE AREA WILL LEAD TO PREVAILING LOWER VISIBILITY AS IT IS.
SO IFR CONDITIONS WILL ENVELOP THE TAF SITES WITH HIGH CONFIDENCE.
CEILINGS WILL ALSO GRADUALLY CREEP DOWN THROUGH THE IFR
CATEGORY...WITH TEMPORARY LIFR BECOMING MORE LIKELY. THESE
CONDITIONS LOOK TO PREVAIL THROUGH THE MORNING WITH HIGH
CONFIDENCE...AND LIKELY INTO THE AFTERNOON AND EVEN EVENING DUE TO
LITTLE MOVEMENT OF THE FRONT. DURING THE EVENING AS THE LOW
APPROACHES...THE WINDS SHOULD INCREASE IN SPEED AND EVENTUALLY
VEER TO SOUTHEAST. AT THAT POINT...SOME SCOURING OF THE CLOUD DECK
MAY OCCUR. WITH THE APPROACH OF THE LOW THOUGH WILL COME ANOTHER
ENHANCED CHANCE FOR SHOWERS. THROUGHOUT THE ENTIRE TAF PERIOD
THERE WILL BE A SMALL AMOUNT OF INSTABILITY...POTENTIALLY
PRODUCING A BRIEF EMBEDDED THUNDERSTORM. THE BEST CHANCE FOR THIS
MAY COME BETWEEN 06Z AND 09Z TUESDAY NIGHT.
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* HIGH CONFIDENCE IN IFR CONDITIONS THROUGH EARLY MORNING.
* HIGH CONFIDENCE -RA WITH PDS RA AND ISOLD +RA.
* MEDIUM CONFIDENCE IN CIGS AND VSBYS THIS AFTERNOON.
* MEDIUM CONFIDENCE IN GENERAL WIND TRENDS BUT LOW CONFIDENCE IN
TIMING OF WSHFT FM NE TO SSE LATER AFTERNOON-EARLY EVENING.
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...AREAS OF MVFR PROBABLE WITH GUSTY WEST TO NORTHWEST
WINDS.
THURSDAY...VFR LIKELY.
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...VFR LIKELY.
MTF/TRS
&&
.MARINE...
320 AM CST
A BIT OF A TRICKY FORECAST TODAY...SPECIFICALLY REGARDING WINDS.
WINDS HAVE BEGUN TO PICK UP SOME THIS MORNING AS LOW PRESSURE
DEEPENS OVER THE OZARKS AND A WARM FRONT LIFTS NORTH ACROSS INDIANA
AND ILLINOIS. TO THE NORTH OF THE FRONT...EXPECT WINDS TO INCREASE
OUT OF THE NORTHEAST...INTO THE 20 TO 25 KT RANGE FOR SOUTHERN
PORTIONS OF LAKE MICHIGAN. A SMALL CRAFT ADVISORY HAS ALREADY BEEN
ISSUED FOR THE ILLINOIS NEARSHORE WATERS. TRICKY PART WILL BE WIND
TRENDS THIS AFTERNOON INTO THE EVENING AS THE FRONTAL TROUGH MOVES
NORTH OVER THE LAKE. WINDS WITHIN THIS ZONE WILL DROP OFF QUITE A
BIT...LIKELY INTO THE 10 TO 15 KT RANGE...AND WAVES WILL LIKEWISE
DROP BELOW CRITERIA FOR SMALL CRAFT ADVISORY. IT APPEARS THERE COULD
BE AROUND A SHORT WINDOW WHERE WE WILL BE BELOW CRITERIA...BUT WITH
UNCERTAINTY IN TIMING HOW MUCH WINDS WILL DIMINISH...WILL NOT MAKE
CHANGES TO HEADLINE AT THIS TIME. BY LATE TONIGHT...WINDS WILL ONCE
AGAIN INCREASE AS THE BOUNDARY LIFTS NORTH...WITH STRONG SOUTH TO
SOUTH-SOUTHWEST WINDS EXPECTED. THE LOW WILL CONTINUE TO DEEPEN AS
IT LIFTS INTO THE NORTHERN HALF OF THE LAKE BY WEDNESDAY AFTERNOON.
GALE FORCE WINDS ARE EXPECTED TO BEGIN WEDNESDAY AFTERNOON FOR THE
SOUTH HALF OF THE LAKE...AND AS A TRAILING COLD FRONT SWINGS ACROSS
THE LAKE WEDNESDAY EVENING...EXPECT GALES TO OCCUR ACROSS THE LAKE.
GALES SHOULD LET UP BY THURSDAY MORNING...BUT EXPECT BREEZY
CONDITIONS TO PERSIST ACROSS THE LAKE AS A MODEST PRESSURE GRADIENT
REMAINS IN PLACE THROUGH THE REMAINDER OF THE WEEK AND INTO THE
WEEKEND. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO NORTHERLY
IS UNTIL 10 PM WEDNESDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744-LMZ745...10 PM
TUESDAY TO 10 PM WEDNESDAY.
GALE WATCH...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...8 AM WEDNESDAY TO 10
PM WEDNESDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ868...4 PM WEDNESDAY TO 4 AM THURSDAY.
&&
$$
