000
FXUS63 KLOT 062025
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
225 PM CST THU MAR 6 2014

.DISCUSSION...
301 AM CST

TEMPERATURES WILL BE THE MAIN FOCUS OF THE FORECAST THIS PERIOD WITH
SEVERAL OPPORTUNITIES FOR MILDER AND EVEN ABOVE NORMAL AIR TO BUILD
INTO THE AREA. SATELLITE IMAGERY SHOWS A MORE AMPLIFIED PATTERN THAN
THIS TIME YESTERDAY THANKS TO AN UPPER LOW SPINNING EASTWARD ACROSS
THE ARKLATEX...WITH A LARGER SCALE TROUGH STRETCHING NORTHWARD TO
THE LOCAL AREA. ANOTHER UPPER LOW IS SPINNING ACROSS WESTERN ONTARIO
WITH A TROUGH AXIS STRETCHING BACK TO BRITISH COLUMBIA. LOW
AMPLITUDE RIDGING IS FOUND ACROSS THE WESTERN U.S. WITH A SHARPENING
RIDGE AXIS OVER THE PACIFIC NORTHWEST AHEAD OF AND APPROACHING UPPER
LOW. AT THE SURFACE...A LARGE HIGH IS OVER SOUTHERN QUEBEC WITH A
RIDGE AXIS EXTENDING BACK ACROSS THE MID MISSISSIPPI RIVER VALLEY
AND ON INTO NORTH TEXAS. LOW PRESSURE IS FOUND ACROSS EASTERN
MONTANA WITH A STRONG SOUTHWESTERLY FLOW TO ITS EAST IN THE GRADIENT
BETWEEN IT AND THE RIDGE TO THE EAST.

TODAY THROUGH SATURDAY...TRANQUIL WEATHER WILL BE IN PLACE TODAY
WITH THE AFOREMENTIONED RIDGE AXIS CROSSING THE AREA. WITH THE UPPER
TROUGH AXIS SHIFTING EAST OF THE AREA THROUGH THE DAY WEAK RIDGING
SPREADING IN BEHIND IT WILL ALLOW MID LEVEL TEMPS WILL WARM THROUGH
THE DAY. SURFACE WINDS WILL BE LIGHT FROM THE SOUTH AND SOUTHEAST
THANKS TO THE SURFACE HIGH SO MIXING WILL BE WEAK AND SHALLOW. MID
AND HIGH CLOUD COVER OVER THE AREA NOW WILL EXIT TO THE EAST THROUGH
THE MORNING BUT RESIDUAL LOWER LEVEL MOISTURE WILL LINGER RESULTING
IN SCATTERED CLOUDS THROUGH THE DAY...WITH SOME CHANCE FOR BROKEN
SKIES NORTHWEST CLOSER TO AN AXIS OF BETTER LOW LEVEL MOISTURE
CURRENTLY IN PLACE. WITH A FAIR AMOUNT OF SUNSHINE FOR MOST AREAS WE
WILL SEE WHAT IT WILL BE CAPABLE OF IN TERMS OF AIDING HIGH TEMPS.
WILL CONTINUE WITH HIGHS IN THE LOWER 30S FOR MOST AREAS...WITH A
FEW MID 30S POSSIBLE IN THE SOUTH...BUT UPPER 20S LIKELY IN THE
NORTHWEST THANKS TO A BIT GREATER COVERAGE OF CLOUDS. THE SURFACE
LOW ACROSS MONTANA THIS MORNING WILL TRACK EAST TO LAKE SUPERIOR BY
FRIDAY AFTERNOON AS AN UPPER TROUGH TRAILS IT. FURTHER MID LEVEL
WARMING WILL BE IN PLACE WITH H85 TEMPS WARMING TO +4 TO 6C. WITH A
BREEZY SOUTHWEST WIND IN PLACE AND A FAIR AMOUNT OF SUNSHINE TEMPS
SHOULD BE PROPELLED INTO THE LOW TO MID 40S WITH LOCAL 925 AND 850MB
TEMP CLIMATOLOGY EVEN SUGGESTING THAT THIS MAY BE CONSERVATIVE.
CLOUDS WILL INCREASE NORTHWEST LATE IN THE DAY AS THE COLD FRONT
ASSOCIATED WITH THE SURFACE LOW REACHES THE AREA. THERE IS STILL
SOME DISAGREEMENT ON HOW QUICKLY THE FRONT ARRIVES...WITH BETTER
SUPPORT FOR A SLOWER ARRIVAL GIVEN THAT THE SURFACE LOW IS PULLING
AWAY FROM THE AREA AND THE INITIAL UPPER TROUGH ASSOCIATED WITH THE
SYSTEM IS TRACKING MORE TO THE EAST THAN SOUTHEAST...WITH A SHARPER
SUBSEQUENT TROUGH PUSHING THE FRONT OUT OF THE AREA SOME TIME
SATURDAY. IF THE FRONT IS FASTER AND ARRIVES LATE IN THE AFTERNOON
AS OPPOSED TO EARLY EVENING THEN HIGH TEMPS MAY BE TEMPERED. WILL
STICK WITH THE SLOWER IDEA AND WARMER TEMPS FOR NOW. SOME PRECIP
DOES LOOK TO ACCOMPANY THE FRONT SO WILL CONTINUE WITH HIGH CHANCE
POPS FRIDAY EVENING/NIGHT. COLDER AIR WILL BE BUILDING IN BUT AM
WONDERING IF THE INITIAL PUSH OF COLD AIR WILL STILL BE MILD ENOUGH
TO KEEP A LONGER PERIOD OF RAIN POTENTIAL FRIDAY EVENING. THE BETTER
PUSH OF COLDER AIR DOES NOT LOOK TO ARRIVE UNTIL THE SECOND MORE
AMPLIFIED TROUGH AXIS ARRIVES SATURDAY MORNING. THUS PRECIP TYPE
FRIDAY EVENING/NIGHT WILL NEED TO BE CLOSELY WATCHED. EITHER WAY
AMOUNTS LOOK TO BE LIGHT BUT SOME LIGHT SNOW ACCUMULATIONS UNDER AN
INCH COULD RESULT ONCE THE TRANSITION TO SNOW OCCURS BEFORE PRECIP
TRANSITIONS OUT OF THE AREA INTO SATURDAY AFTERNOON. HIGH PRESSURE
WILL BE SPREADING INTO THE AREA INTO SATURDAY EVENING. H85 TEMPS
WILL HAVE COOLED TO AROUND -6C WHICH IS STILL WARMER THAN WE SAW
YESTERDAY SUGGESTING THAT HIGHS WILL BE AROUND 30 IN THE NORTH AND
IN THE LOW TO EVEN MID 30S SOUTH SATURDAY.

SUNDAY THROUGH WEDNESDAY...AS THE FRIDAY NIGHT/SATURDAY SYSTEM IS
ONGOING AN UPPER TROUGH WILL BE SPLITTING FROM THE MAIN FLOW AND
CUTOFF OVER THE DESERT SOUTHWEST. THIS WILL LEAVE AN ACTIVE NORTHERN
STREAM FLOW IN PLACE FROM THE PACIFIC NORTHWEST/BRITISH COLUMBIA TO
THE GREAT LAKES AND THE MID ATLANTIC THROUGH THE REST OF THE WEEKEND
AND INTO NEXT WEEK. INITIALLY...THERE WILL BE FAIRLY SUBSTANTIAL
RIDGING ACROSS THE WESTERN U.S. WHICH WILL BREAK DOWN INTO EARLY
NEXT WEEK BUT ALLOW THE BUILT UP WARMER AIR TO SLIDE EASTWARD AS THE
NORTHERN STREAM BECOMES BETTER ESTABLISHED. THE SURFACE HIGH FROM
SATURDAY WILL QUICKLY SHIFT TO THE SOUTHEAST OF THE AREA WITH A
STRONG SOUTHWESTERLY LOW LEVEL FLOW SETTING UP. THIS WILL COMBINE
WITH THE WARM ADVECTION ALOFT TO START A NICE WARM UP SUNDAY AND
MONDAY. EXPECT HIGHS TO RANGE FROM THE MID 30S TO AROUND 40 SUNDAY
WHICH COULD BE CONSERVATIVE WITH STRONG ENOUGH SOUTHWEST WINDS. THE
WARMER DAY LOOKS TO BE MONDAY...WITH H85 TEMPS PUSHING +10C
SUPPORTING HIGHS AROUND 40 NORTH THE NEAR 50 SOUTH IF THINGS WORK
OUT. THE ISSUE MAY BE THAT STRONGER ENERGY WILL BE WORKING THROUGH
THE FLOW LEADING TO AN AMPLIFICATION OF A TROUGH WHICH WOULD PUSH
THE COOLER AIR SOUTHWARD. THIS LOOKS TO OCCUR MORE INTO TUESDAY SO
WILL KEEP WITH THE WARM MONDAY FORECAST. THE SPREAD OF THE COLDER
AIR SOUTHWARD WOULD LIKELY BE SLOW GIVEN THE LOW AMPLITUDE/BROADNESS
OF THE TROUGH SO TUESDAY SHOULD STILL BE A RELATIVELY MILD DAY.
CONFIDENCE FALLS OFF INTO WEDNESDAY AS THE UPPER FLOW STARTS TO
BECOME MORE COMPLEX WITH A TROUGH POTENTIALLY WORKING SOUTHEAST INTO
THE WESTERN U.S. AND POTENTIALLY PHASING WITH THE CUTOFF UPPER
TROUGH WHICH WILL THEN BE OVER NORTHERN MEXICO. AN OVERALL
AMPLIFICATION OF THE PATTERN DOES LOOK TO OCCUR SO PRECIP CHANCES
MAY RETURN MIDWEEK.

MDB

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* NONE.

JEE

//DISCUSSION...UPDATED 18Z...

QUIET WEATHER IS EXPECTED THROUGH THE PERIOD. HIGH PRESSURE IS
CENTERED OVER NEW ENGLAND WITH ITS RIDGE EXTENDING THROUGH TEXAS.
THE RIDGE WILL SHIFT EAST THROUGH TONIGHT WITH WINDS SLOWLY
VEERING TO THE SSW BY FRIDAY AFTERNOON. WIND SPEEDS WILL DIMINISH
THIS EVENING TO ARND 5 KT BEFORE PICKING BACK UP LATE TONIGHT AND
REMAIN ARND 7-8 KT. CIGS AND VSBY WILL BE VFR.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...CHANCE OF RAIN OR SNOW. MVFR CIGS/VIS POSSIBLE.

SATURDAY...CHANCE SNOW EARLY...MVFR CIGS/VIS POSSIBLE. VFR/WX NIL
OVERNIGHT.

SUNDAY...VFR/WX NIL.

MONDAY...VFR/WX NIL.

TUESDAY...CHANCE OF RAIN DAYTIME. CHANCE OF SNOW OVERNIGHT. MVFR
CIGS/VIS POSSIBLE.

WEDNESDAY...SLIGHT CHANCE OF SNOW WITH MVFR CIGS/VIS POSSIBLE
EARLY. BECMG VFR/WX NIL.

KREIN

&&

.MARINE...
225 PM CST

HIGH PRESSURE CENTERED OVER NEW ENGLAND THIS AFTERNOON WILL CONTINUE
TO DRIFT OFF TO THE EAST-SOUTHEAST OFF THE COAST TONIGHT. FARTHER
WEST...AN AREA OF LOW PRESSURE WAS DEVELOPING OVER THE NORTHERN HIGH
PLAINS. THIS LOW WILL MOVE SLOWLY EAST ACROSS THE NORTHERN GREAT
LAKES AND NORTHEASTERN ONTARIO FRIDAY AND INTO QUEBEC FRIDAY NIGHT.
WINDS WILL BACK TO THE SOUTH AND SOUTHWEST AHEAD OF THIS FRONT...
INCREASING IN SPEED INTO THE 20-30 KT RANGE (HIGHEST NORTH) LATER
TONIGHT INTO FRIDAY AS THE GRADIENT INCREASES BETWEEN THE DEPARTING
HIGH AND THE APPROACHING LOW AND COLD FRONTAL TROUGH. THE FRONT WILL
PUSH SOUTHEAST ACROSS THE LAKE LATE FRIDAY INTO FRIDAY NIGHT...WITH
WINDS VEERING TO THE NORTH AND INCREASING INTO THE 20-25 KT RANGE
BEHIND THE COLD FRONT BY EARLY SATURDAY MORNING. HIGH PRESSURE WILL
THEN BUILD SOUTHEAST FROM THE NORTHERN PLAINS BEHIND THE
FRONT...BECOMING ELONGATED ACROSS THE OHIO VALLEY SATURDAY NIGHT.
THIS WILL ALLOW WINDS TO DIMINISH AND BACK TO THE WEST
WEST-SOUTHWEST BY SUNDAY...WHILE ANOTHER LOW BEGINS TO DEVELOP
ACROSS THE CANADIAN PRAIRIES AND TRACKS ACROSS THE NORTHERN LAKES
INTO MONDAY.

AFTERNOON POLAR SATELLITE IMAGERY INDICATES CONSIDERABLE ICE COVER
OVER MUCH OF THE LAKE PARTICULARLY THE WESTERN 1/3 AND THE NORTHERN
QUARTER OF SO. ICE COVERAGE OR SHORT FETCH DUE TO NARROW CHANNELS OF
OPEN WATER SHOULD LIMIT WAVE DEVELOPMENT FOR MUCH OF THE EARLY PART
OF THE FORECAST PERIOD. IN FACT...HAVE OMITTED WAVE FORECASTS FOR
NORTHERN LM OPEN WATERS...AND LOCAL IL/IND NEARSHORE WATERS WHICH
APPEAR TO BE MOSTLY ICED-OVER.

RATZER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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