🚀 go-pugleaf

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1139 AM CST FRI DEC 14 2012

DISCUSSION...
942 AM CST

NOT TOO MUCH NEW MODEL OUTPUT TO PORE OVER AT THIS POINT BUT
NOTHING STICKS OUT TO CONVINCE TO MAKE ANY CHANGES TO GOING
FORECAST GRIDS AND DERIVED ALPHA-NUMERIC AND GRAPHIC PRODUCTS.
DID ADD A LITTLE MORE RESOLUTION TO THE INCREASING POP VALUES W
TO E ACROSS THE LOCAL FORECAST AREA DURING THE OVERNIGHT HOURS.

TRS

//PREV DISCUSSION...

329 AM...SEVERAL FORECAST CONCERNS/CHALLENGES INTO NEXT WEEK
INCLUDING...ABOVE NORMAL TEMPS THROUGH EARLY NEXT WEEK...PRECIP
ARRIVAL/TIMING LATE TONIGHT INTO SATURDAY MORNING...CHANCE FOR
THUNDER SATURDAY...POTENTIAL FOR FOG/DRIZZLE SATURDAY NIGHT INTO
SUNDAY MORNING...THEN A CHANCE OF RAIN OR PERHAPS SOME SNOW
TUESDAY AND AGAIN THURSDAY.

LOW PRESSURE WILL DEVELOP OVER THE WESTERN HIGH PLAINS LATER TODAY
AND TONIGHT AND TRACK NORTHEAST ACROSS THE WESTERN LAKES SATURDAY
NIGHT INTO SUNDAY KEEPING THE AREA WELL INTO THE WARM SECTOR. WHILE
LESS BREEZY TODAY THAN THURSDAY...SOUTHEASTERLY FLOW WILL LIKELY
KEEP THE IL SHORE COOLER THEN THE REST OF THE AREA WHICH SHOULD
EASILY REACH MID/UPPER 40S AND WITH EXPECTED SUNSHINE...SOME AREAS
WILL PROBABLY TAG 50. EXPECT LOW TEMPS THIS EVENING THEN STEADY OR
PERHAPS SLOWLY RISING OVERNIGHT...AND DEPENDENT ON HOW FAST THICKER
CLOUD COVER...AND EVENTUALLY PRECIP...ARRIVES.

A BAND OF RAIN WILL SPREAD NORTHEAST ACROSS THE AREA OVERNIGHT INTO
SATURDAY MORNING. LOW LEVELS INITIALLY ARE RATHER DRY BUT THIS MAY
NOT HAVE MUCH IMPACT GIVEN RATHER STRONG OMEGA BY 12Z OR SO. ACTUAL
DURATION OF PRECIP AT ANY ONE POINT MIGHT END UP BEING ONLY A FEW
HRS AND THIS COULD LIMIT QPF AMOUNTS TO PERHAPS A HALF INCH...MAYBE
LESS. LOW LEVEL MOISTURE CONTINUES TO SPREAD NORTH MUCH OF SATURDAY
AND SATURDAY NIGHT SO TEMPS RISING INTO THE UPPER 40S/LOWER 50S BY
AFTERNOON LOOK REASONABLE ALONG WITH DEW POINTS RISING INTO THE MID
40S. THE GRADIENT TIGHTENS EARLY SATURDAY MORNING AND SOUTHERLY
WINDS GUSTING AS HIGH AS 30 MPH ARE POSSIBLE. A BIT OF SOUTHEASTERLY
GRADIENT COULD AGAIN KEEP THE IL SHORE COOLER AND FOG POTENTIAL WILL
BEGIN TO INCREASE NEAR THE LAKE THROUGH SATURDAY AFTERNOON. DON/T
HAVE MUCH CONFIDENCE REGARDING FOG POTENTIAL AND IF ANY DENSE FOG
COULD FORM...ESPECIALLY GIVEN THE TRACK OF THE SURFACE LOW WELL
NORTH OF THE AREA AND GIVEN SEVERAL DAYS OF ABOVE NORMAL TEMPS AND
MOSTLY SUNNY SKIES...GROUND WILL NOT BE PARTICULARLY COLD EITHER AND
FOR NOW HAVE NOT INCLUDED ANY FOG DURING THIS PERIOD.

BEST THUNDER POTENTIAL APPEARS TO BE IN ASSOCIATION WITH THE STRONGER
OMEGA AND MODEST WARM AIR ADVECTION SATURDAY MORNING...PERHAPS INTO
EARLY SATURDAY AFTERNOON DEPENDING ON TIMING. BUT STILL ONLY WORTH A
SLIGHT CHANCE MENTION AT THIS POINT AS BETTER OR MORE ORGANIZED
CONVECTION SHOULD REMAIN SOUTH OF THE AREA.

SUNDAY LOOKING WARM TO START BUT CONFIDENCE ON SPECIFICS DECREASES
WITH TIME AS A WEAK COLD FRONT WILL BE MOVING ACROSS THE AREA...
MOST LIKELY BY EARLY/MID AFTERNOON. MILD/WARM TEMPS TO START WILL
PROBABLY BE SLOWLY FALLING WITH THIS FRONT AND IT ALSO APPEARS
THERE IS THE POTENTIAL OF POST FRONTAL PRECIP SUNDAY AFTERNOON
WITH THERMAL PROFILES SUGGESTING IT WILL BE WARM ENOUGH TO BE ALL
LIQUID...PERHAPS A COMBINATION OF SHOWERS/DRIZZLE. COLDER AIR
FILTERS INTO THE AREA SUNDAY NIGHT BUT STILL ABOVE NORMAL INTO
MONDAY.

BEYOND MONDAY...CONFIDENCE IS LOW. MODEL DIFFERENCES WITH A POSSIBLE
LOW PASSAGE AND ITS TRACK TUESDAY TIME FRAME WARRANT CHANCE POPS AND
WITH HIGHS PERHAPS ONLY IN THE 30S...PRECIP TYPE WILL NEED TO BE
MONITORED BUT A POTENTIALLY STRONGER STORM MAY AFFECT THE REGION IN
THE THURSDAY TIME-FRAME AND AGAIN WITH AN UNCERTAIN TRACK FROM THIS
DISTANCE...PRECIP TYPE WILL NEED TO BE MONITORED. CMS

&&

AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* SHOWERS MOVE IN SATURDAY MORNING WITH CIGS RAPIDLY FALLING INTO
  THE MVFR/IFR RANGE.

* STRONGER SHOWERS WILL BE ASSOCIATED WITH MVFR VSBY.

* GUSTY SE WINDS BECOME S THROUGH THE MORNING.

JEE

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

HIGH PRESSURE REMAINS OVER THE GREAT LAKES WITH MARGINAL WINDS
VARYING FROM SOUTHEAST TO SOUTHWEST ACROSS THE REGION. WINDS AT OR
BELOW 10 KT ARE EXPECTED THROUGH TONIGHT WITH CIGS INCREASING AND
SLOWLY LOWERING.

LOW PRESSURE EXITING THE GREAT PLAINS WILL AFFECT THE REGION
TOMORROW WITH RAIN MOVING INTO NORTH CENTRAL IL IN THE EARLY
MORNING HOURS. GUIDANCE INDICATES THE COLUMN WILL MOISTEN QUICKLY
WITH IFR CIGS MOVING IN SHORTLY AFTER THE RAIN BEGINS. THE
STRONGER SHOWERS WILL RESULT IN MVFR VSBYS. GUIDANCE INDICATES
THE MAIN BAND OF SHOWERS MAY MOVE NORTH OF THE EASTERN TERMINALS
BY SATURDAY AFTERNOON AS THE LOWS WARM FRONT LIFTS NORTH INTO
WISCONSIN. AS SUCH PUT A VCSH IN FOR THE EASTERN TERMINALS.
HOWEVER COULD SEE SHOWERS HANGING AROUND ORD ESPECIALLY IF THE
WARM FRONT DOES NOT LIFT AS FAR AS GUIDANCE INDICATES. SHOWERS ARE
EXPECTED THROUGH THE FORECAST PERIOD AT RFD. LOW CIGS ARE EXPECTED
TO REMAIN OVER ALL OF THE TERMINALS THROUGH SATURDAY
AFTERNOON...WITH NO IMPROVEMENT EXPECTED UNTIL SUNDAY
MORNING/AFTERNOON.

SOUTHEAST WINDS BECOME SOUTH BEHIND THE WARM FRONT AND GUSTS BTWN
15 AND 20 KT ARE EXPECTED THROUGH THE AFTERNOON.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH CONFIDENCE IN ALL FORECAST TRENDS.

* MEDIUM-HIGH CONFIDENCE IN TIMING OF RAIN MOVING IN.

* MEDIUM CONFIDENCE IN TIMING AND VALUES OF LOW CIGS...CIGS WILL
  FALL SHORTLY AFTER RAIN ONSET AND COULD BE LOWER THAN INDICATED.

* MEDIUM-LOW CONFIDENCE IN RAIN-FREE PERIOD SATURDAY AFTERNOON.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...

SATURDAY NIGHT AND SUNDAY...CHANCE OF SHOWERS. MVFR/IFR POSSIBLE.

MONDAY...SLGT CHC LGT SN MAINLY AT NGT.

TUESDAY...SLGT CHC LGT RA/SN.

WEDNESDAY...VFR. CHC RA/SN WED NGT.

THURSDAY...CHC RA/SN. MVFR CIGS POSSIBLE

RATZER

&&

MARINE...
232 AM CST

MAIN MARINE FORECAST CONCERNS ARE STRONG SOUTHEAST WINDS 25-30 KTS
DEVELOPING LATE TONIGHT AND SATURDAY. WHILE GALE HEADLINES NOT
ANTICIPATED AT THIS TIME...SMALL CRAFT ADVISORY CONDITIONS ARE
LIKELY FOR THE ILLINOIS/INDIANA SHORES SATURDAY/SATURDAY NIGHT.

LOW PRESSURE OVER SOUTHERN QUEBEC WILL CONTINUE TO MOVE AWAY TO THE
EAST TODAY...WITH A COLD FRONT TRAILING ACROSS SOUTHERN LAKE
MICHIGAN AND THE ILLINOIS AND WISCONSIN BORDER REGION BECOMING
STATIONARY DURING THE MORNING. BY THIS AFTERNOON...LOW PRESSURE WILL
DEVELOP ACROSS THE HIGH PLAINS OF COLORADO. THIS LOW WILL THEN LIFT
NORTHEAST ACROSS KANSAS TONIGHT...AND ACROSS IOWA ON SATURDAY. IN
RESPONSE...WINDS WILL SHIFT TO THE SOUTHEAST AND INCREASE ACROSS
LAKE MICHIGAN LATE TONIGHT AND SATURDAY...AS PRESSURE GRADIENT
TIGHTENS AHEAD OF THE APPROACHING LOW. FORECAST SOUNDINGS INDICATE
WINDS WILL PICK UP TO 20-25 KTS TONIGHT...AND TO 30 KTS ON SATURDAY
BEFORE THE GRADIENT BEGINS TO WEAKEN SATURDAY NIGHT IN THE VICINITY
OF THE LOW CENTER ITSELF. MODEL GUIDANCE DOES SHOW SOME SPREAD IN
THE VARIOUS SOLUTIONS WITH RESPECT TO THE TRACK OF THE ACTUAL LOW
CENTER ACROSS THE AREA EARLY SUNDAY...BUT GENERALLY A TRACK ACROSS
THE NORTHERN PART OF THE LAKE DURING THE EARLY AFTERNOON IS FAVORED.
THIS WILL ALLOW WINDS TO VEER INITIALLY TO THE SOUTH BY SUNDAY
AFTERNOON AND THEN WEST BY SUNDAY EVENING. AGAIN...MODEL DIFFERENCES
EXIST IN WIND SPEED BY LATE SUNDAY...THOUGH HAVE MAINTAINED A
FORECAST OF 15-20 KTS INTO MONDAY WHICH IS STRONGER THAN THE WEAKER
MODEL SOLUTIONS. THE LOW WILL THEN WEAKEN AND PULL AWAY
TUESDAY...WITH WEAK HIGH PRESSURE RIDGING MOVING IN TUESDAY NIGHT.

RATZER

&&

LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
     LMZ745...6 AM SATURDAY TO 4 AM SUNDAY.

&&

$$