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 02Z...
* BRIEF RAIN SHOWERS THROUGH EVENING. MORE WIDESPREAD ACTIVITY
MOVING IN OVERNIGHT WITH THE SMALL CHANCE OF THUNDER DURING THE
DAY TOMORROW.
* GRADUALLY LOWERING VISIBILITY EVEN PRIOR TO THE RAIN.
* QUICKLY LOWERING CEILINGS OVERNIGHT...DROPPING TO IFR BY LATE
TONIGHT.
* WINDS EAST NORTHEAST AND INCREASING IN SPEED
OVERNIGHT...EVENTUALLY VEERING TO THE SOUTHEAST TOMORROW.
//DISCUSSION...UPDATED 00Z...
ORGANIZING LOW PRESSURE IN THE SOUTHERN PLAINS WILL CONTINUE TO
DEVELOP A WARM FRONT SOUTH OF THE TERMINALS THROUGH TONIGHT. THIS
WILL CREEP NORTHWARD AND BE ASSOCIATED WITH LOWER
CEILINGS...VISIBILITY...AND RAIN. SOME OF THE LOWER VISIBILITIES
IN FOG MAY ARRIVE BEFORE THE ACTUAL RAINFALL...SUCH AS HAS BEEN
SEEN IN CENTRAL IL IMMEDIATELY ALONG THE BOUNDARY. RAIN SHOULD
BEGIN MORE AS SHOWERS AND TRANSITION TO TRUE RAIN BY LATE TONIGHT
THROUGH THE MORNING TOMORROW. THEN MORE SHOWERS ARE EXPECTED DURING
THE AFTERNOON TOMORROW. GIVEN THE PLACEMENT OF THE FRONT DIRECTLY
OVER NORTHERN IL AND SOUTHERN LAKE MICHIGAN TOMORROW...IT IS
LIKELY THAT IMPROVEMENT IN CEILINGS AND EVEN POSSIBLY VISIBILITY
MAY BE VERY SLOW EVEN ONCE RAINFALL BECOMES MORE SHOWERY. WHAT
THE FRONT PLACEMENT ALSO INFERS IS THAT EXACT TIMING OF THE WIND
SHIFT 12 TO 18 HOURS IN ADVANCE IS TRICKY AND THUS THE TIMING OF
THE SHIFT TO SOUTHERLY IN THE TAFS ARE WITH LOW CONFIDENCE.
ELEVATED PARAMETERS FOR THUNDER DO GRADUALLY COME TO
FRUITION...HOWEVER THE BETTER CHANCES ARE TO THE SOUTHWEST TOWARDS
STL/UIN/PIA THROUGH THE TAF PERIOD.
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* HIGH CONFIDENCE THAT ANY SHOWERS BEFORE 05Z WOULD BE BRIEF AND
MEDIUM CONFIDENCE THAT THEY WOULD NOT DROP CIGS/VSBYS BELOW VFR.
* HIGH CONFIDENCE IN RAIN OCCURRING AT THE AIRPORTS OVERNIGHT AND
TOMORROW. MEDIUM CONFIDENCE IN FLUCTUATING VISIBILITY DURING
THE RAIN.
* HIGH CONFIDENCE IN IFR CEILINGS BY LATE TONIGHT TOWARDS DAYBREAK
AND LASTING THROUGH THE MORNING TOMORROW...BUT MEDIUM CONFIDENCE
IN JUST HOW LOW THEY WILL DROP. LIFR IS POSSIBLE.
* MEDIUM CONFIDENCE IN WIND TRENDS TONIGHT AND LOW CONFIDENCE IN
THE TIMING OF THE WIND SHIFT TO SOUTH SOUTHEAST TOMORROW. IT MAY
END UP BEING LATE IN THE DAY
//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
&&
.MARINE...
404 PM CST
AS SEVERAL SYSTEMS WILL BE EXITING AND DEVELOPING OVER THE NEXT
COUPLE OF DAYS...CONDITIONS ACROSS THE LAKE WILL VARY FROM ONE
SIDE TO THE OTHER BEFORE CONDITIONS OVER THE ENTIRE LAKE REALLY
DETERIORATE BY MID WEEK. HIGHER WINDS AND WAVES CURRENTLY BEING
REPORTED OVER THE NORTHERN HALF OF THE LAKE TODAY AS AN AREA OF
LOW PRESSURE EXITS OFF TO THE NORTHEAST INTO QUEBEC...WITH
SIGNIFICANTLY LOWER WINDS AND WAVES OVER THE SOUTHERN HALF AS A
RIDGE OF HIGH PRESSURE IS SITUATED IN THIS AREA. ALTHOUGH WITH
THIS HIGH LIFTING NORTH AND A DEVELOPING AREA OF LOW PRESSURE
MOVING NORTH...CONDITIONS OVER THE NORTH WILL SUBSIDE WITH WINDS
AND WAVES ACROSS THE SOUTHERN HALF INCREASING/BUILDING LATE
TONIGHT INTO EARLY TUESDAY MORNING. THIS WILL BE ONGOING AS AN
APPROACHING TROUGH OF LOW PRESSURE HELPS INCREASE THE PRESSURE
GRADIENT. THIS LOW WILL CONTINUE TO LIFT NORTH ACROSS THE LAKE
LATE IN THE DAY TUESDAY INTO TUESDAY NIGHT WITH WINDS AND WAVES
INCREASING ACROSS THE REMAINDER OF THE LAKE. AS THE LOW MOVES
NORTH OVER THE LAKE TUESDAY NIGHT INTO WEDNESDAY WIND DIRECTIONS
AND SPEEDS WILL BE VARYING BEFORE MUCH COLDER AIR MOVES OVER THE
LAKE ON WEDNESDAY. THIS WILL RESULT IN STRONG SOUTHWEST TO WEST
GALES TO POSSIBLY OCCUR. THESE STRONGER WINDS COULD OCCUR INTO
WEDNESDAY NIGHT BEFORE WINDS SLOWLY COME DOWN. ALTHOUGH WINDS WILL
BE DIMINISHING...WAVES COULD REMAIN ELEVATED INTO THE REMAINDER OF
THE WORK WEEK.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...6 AM TUESDAY TO 10 PM
WEDNESDAY.
&&
$$
