🚀 go-pugleaf

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1215 PM CST SUN FEB 10 2013

DISCUSSION...

325 AM...ISSUED A FREEZING RAIN ADVISORY EARLIER THIS MORNING FOR
PARTS OF NORTHERN IL. TEMPS HAD DROPPED INTO THE 20S ACROSS THE
ADVISORY AREA UNDER CLEAR SKIES SATURDAY EVENING. AS CLOUDS MOVED
BACK NORTH...TEMPS HAVE RISEN INTO THE UPPER 20S AND LOWER 30S.
BUT WITH A DECENT BAND OF LIGHT RAIN MOVING NORTH...IT WAS JUST
TOO CLOSE TO CALL REGARDING HOW FAST TEMPS WOULD WARM ABOVE
FREEZING AND WHEN THIS LIGHT RAIN OR LIGHT FREEZING RAIN WOULD
ARRIVE. WHILE TEMPERATURES WILL LIKELY WARM ABOVE FREEZING IN THE
SOUTHERN PARTS OF LEE/DE KALB/KANE COUNTIES AS PRECIP BEGINS...
PLAN TO LET THE ADVISORY RIDE FOR NOW AND CAN ALWAYS UPDATE LATER
PRIOR TO EXPIRATION AS NEEDED. PRECIP AMOUNTS WITH THIS FIRST BAND
WILL BE RATHER LIGHT...WELL UNDER A TENTH OF AN INCH AND EVEN
THOUGH OBSERVATIONAL TEMPS MAY BE AT OR ABOVE FREEZING...SOME
SURFACES THAT WERE EXPOSED TO TEMPS IN THE 20S SATURDAY EVENING
COULD DEVELOP SOME GLAZING. FURTHER NORTH TOWARD THE WI BORDER
WHERE A DEEPER SNOW PACK EXISTS...MIGHT TAKE SEVERAL MORE HOURS TO
GET TEMPS ABOVE FREEZING. OTHER AREAS OUTSIDE THE ADVISORY
INCLUDING PARTS OF NORTHERN COOK/NORTHERN DUPAGE AND NORTHWEST
INDIANA ALSO MAY BE CLOSE TO FREEZING AS PRECIP BEGINS AND MAY SEE
POCKETS OF LIGHT FREEZING RAIN.

LOW PRESSURE OVER NEBRASKA WILL MOVE NORTHEAST TODAY AND TONIGHT
REACHING THE NORTHERN GREAT LAKES MONDAY. A RATHER STRONG UPPER
WAVE WILL MOVE ACROSS THE REGION LATER THIS MORNING INTO THIS
AFTERNOON. A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS ALREADY
MOVING NORTHEAST INTO MISSOURI/ARKANSAS. THIS ACTIVITY WILL
SPREAD/DEVELOP NORTHEAST WITH THIS WAVE THIS MORNING. COULD BE A
SHORT BREAK BETWEEN CURRENT LIGHT PRECIP AND MORE MODERATE/
HEAVIER PRECIP BUT EXPECT THE GAP TO BE TOO SHORT TO TRY TO TIME
IN THE GRIDS. A FEW RUMBLES OF THUNDER WILL REMAIN POSSIBLE WITH
THE STRONGER CELLS. DRY SLOT ROTATES ACROSS THE AREA THIS EVENING
ENDING ANY SIGNIFICANT PRECIP WITH PERHAPS SOME SHOWERS STILL
POSSIBLE NEAR THE WI BORDER AND LINGERING SHOWERS EXITING
NORTHWEST INDIANA. COULD ALSO BE SOME PATCHY DRIZZLE.

TEMPS WILL SLOWLY RISE THROUGH THE 30S THIS MORNING AND INTO THE
40S THIS AFTERNOON. EXPECT HIGH TEMPS TO BE SOMEWHERE IN THE LATE
AFTERNOON OR EARLY EVENING TIME FRAME BEFORE COLDER AIR SPREADS
ACROSS THE AREA LATER THIS EVENING AND OVERNIGHT. WITH SUCH A DEEP
SNOW PACK ACROSS THE FAR NORTHERN COUNTIES...WOULD EXPECT SOME FOG
POTENTIAL THIS AFTERNOON INTO THIS EVENING. CONFIDENCE FAIRLY LOW
REGARDING HOW LOW VISIBILITIES MAY DEVELOP BUT WORTHY OF SOME FOG
MENTION.

SOUTHEASTERLY WINDS WILL INCREASE TODAY WITH GUSTS INTO THE 30-35
MPH RANGE POSSIBLE. WINDS MAY DIMINISH A BIT THIS EVENING AS THEY
SWING AROUND SOUTHWESTERLY BUT WILL STEADILY INCREASE OVERNIGHT
INTO MONDAY MORNING WITH GUSTS AS HIGH AS 40 MPH FOR MOST OF
MONDAY. WILL NEED TO MONITOR FUTURE GUIDANCE AS GUSTS WILL BE
APPROACHING WIND ADVISORY LEVELS. SNOW SHOWERS/FLURRIES WILL
SPREAD ACROSS THE AREA MONDAY WITH THE COLDER AIR WITH PERHAPS A
DUSTING OF SNOW POSSIBLE...MAINLY OVER NORTHERN PARTS OF THE AREA.
CLOUD COVER COULD PERSIST THROUGH MONDAY NIGHT AND INTO TUESDAY
AND CONTINUED WITH MORE PESSIMISTIC TREND IN THE GRIDS...THOUGH
SKY CONDITIONS LIKELY TO BE EITHER CLOUDY...IF CLOUDS HANG ON...OR
CLEAR IF CLOUDS BREAK.

MODELS STILL DIFFER REGARDING THE NEXT CLIPPER LIKE LOW TO AFFECT
THE REGION THURSDAY INTO FRIDAY. TEMPS AHEAD OF THIS SYSTEM LIKELY
TO BE RATHER MILD...DEPENDING ON THE TRACK. THUS COULD BE A MIX OF
RAIN/SNOW TO START THEN SNOW THURSDAY NIGHT INTO FRIDAY GIVEN THE
EXPECTED ARRIVAL OF COLDER AIR. DETAILS STILL SOMEWHAT UNCERTAIN
FROM THIS DISTANCE AND CONTINUED CHANCE POPS. CMS

&&

AVIATION...

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

* MVFR CIGS TRENDING TO IFR BY EARLY THIS AFTN. THEN IFR CIGS
  REMAIN THRU 03Z...THEN SHUD BEGIN TO TREND BACK TO MVFR.

* SE WINDS SLOWLY INCREASING WITH SUSTAINED TO 19KT AND GUSTS TO
  25KT.

* LGT RA CONTINUES AND AT TIMES WILL REDUCE VSBYS TO ARND 3SM THRU
  20Z. THEN RA SHUD COME TO AN END ARND 23Z.

BEACHLER

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

COMPLEX WEATHER SYSTEM CONTINUES TO PRODUCE LIGHT RA ACROSS
NORTHERN IL/NORTHWEST IN AIRFIELDS THIS AFTN. A NARROW CHANNEL OF
IFR CIGS STRETCHES FROM WEST OF RFD TO SOUTHEAST IL...AND
CONTINUES TO LIFT NORTH APPROACHING THE TAF SITES. EXPECT CIGS TO
STEADILY LOWER TOWARDS IFR CONDS BY 20Z WITH CIGS GENERALLY ARND
800FT. IN ADDITION THE WIND GRADIENT HAS BEGUN TO
TIGHTEN...RESULTING IN OCCASIONAL GUSTS TO 20-25KT. THIS WILL THEN
PERSIST THROUGH THE LATE EVENING HOURS. THEN A DRY WEDGE SHUD
ARRIVE OVERHEAD AND BRING AN END TO THE PRECIP ARND 23Z AND WIND
GUSTS SHUD BEGIN TO INCREASE AGAIN TO ARND 28KT BY DAYBREAK MON.
IN ADDITION IT APPEARS CIGS SHUD BEGIN TO LIFT CIGS BACK TO MVFR
PSBLY FOR A SHORT PERIOD AT DAYBREAK TO VFR...BEFORE DROPPING BACK
TO MVFR CIGS BY MID-MORNING MON. GUIDANCE WAS INDICATING SOME
LIGHT SNOW WITH THE COLDER AIR ARRIVING MON...HOWEVER IT REMAINS A
LOW CONFIDENCE. SO AT THIS POINT HAVE HELD OFF ON MENTIONING ANY
PRECIP FOR MON MORNING. FLURRIES LOOK PROBABLE FOR MON.

BEACHLER


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

* MEDIUM CONFIDENCE IN CIGS FORECAST OF IFR.

* HIGH CONFIDENCE IN WIND DIR/SPEED/GUSTS.

* LOW CONFIDENCE IN END TIMING OF PRECIP...AND VSBY IMPROVEMENT.

* MEDIUM CONFIDENCE CIGS WILL LIFT TO MVFR ARND DAYBREAK MON.

BEACHLER

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

MONDAY NIGHT...MVFR POSSIBLE.

TUESDAY...VFR.

WEDNESDAY...VFR.

THURSDAY...CHANCE -RASN...MVFR POSSIBLE.

FRIDAY...CHANCE OF SNOW AND MVFR.

SATURDAY...VFR.

MDB

&&

MARINE...
303 AM CST

HIGH PRESSURE IS DEPARTING TO THE EAST WHILE LOW PRESSURE MOVES
NORTHEASTWARD FROM WESTERN KANSAS/NEBRASKA. WARM ADVECTION IS
UNDERWAY ACROSS MUCH OF LAKE MICHIGAN EARLY THIS MORNING AS THE LOW
LIFTS NORTHEASTWARD WITH WINDS STEADILY PICKING UP AS THE PRESSURE
GRADIENT TIGHTENS. LOW AND MID LEVEL WINDS WILL RAMP UP
SUBSTANTIALLY INTO THE AFTERNOON BUT A TEMPERATURE INVERSION OVER
THE COLD LAKE WATERS WILL KEEP SPEEDS LIMITED TO AROUND 30 KT ACROSS
THE LAKE THROUGH THE AFTERNOON BUT OCCASIONAL GUSTS TO NEAR 35 KT
GALES ARE A GOOD POSSIBILITY FOR A FEW HOURS FROM MID TO LATE
AFTERNOON. WILL HOLD OFF ON GALE HEADLINES FOR THIS AFTERNOON WITH
THE WINDOW RATHER SHORT AND SPEEDS MARGINAL. SPEEDS WILL EASE JUST A
BIT THIS EVENING AS THE LOW REACHES SOUTHEAST MINNESOTA BUT WILL
AGAIN INCREASE LATE TONIGHT WITH THE LOW REACHING NORTHERN LAKE
MICHIGAN TOWARD DAYBREAK. COLDER AIR WILL WRAP IN BEHIND THE LOW
WHICH WILL ALLOW UNSTABLE CONDITIONS TO DEVELOP ONCE AGAIN AS WINDS
TURN MORE WESTERLY THEN NORTHWESTERLY LATE IN THE DAY. STRONGEST
SPEEDS WILL BE ACROSS CENTRAL AND SOUTHERN LAKE MICHIGAN WITH 40 KT
GALES LIKELY AND A SHORT PERIOD OF 45 KT GALES VERY POSSIBLE DURING
THE LATE AFTERNOON HOURS. THERE WILL BE A BIT OF A WEAKNESS IN THE
GRADIENT ACROSS NORTHERN LAKE MICHIGAN THANKS TO THE LOW PASSING
JUST ABOUT OVERHEAD OF THAT AREA BUT THERE MAY BE A SHORT PERIOD
WHERE SOME GALE FORCE GUSTS COULD OCCUR LATE IN THE DAY. WILL GO
AHEAD AND UPGRADE THE GALE WATCH TO A GALE WARNING AND MOVE THE
START TIME UP TO 09Z. WINDS WILL DROP BELOW GALE FORCE LATER MONDAY
EVENING AS HIGH PRESSURE RIDGING APPROACHES INTO TUESDAY MORNING.
ANOTHER LOW LOOKS TO PASS WELL NORTH OF THE LAKE WEDNESDAY WITH A
WEAK FRONTAL BOUNDARY PASSING BY. THE NEXT LOW TO DIRECTLY AFFECT
THE LAKE LOOKS TO DO SO THURSDAY WHICH WILL BRING AN INCREASE IN
WIND SPEEDS BEHIND IT. A PERIOD OF WEST TO NORTHWEST GALES ARE A
POSSIBILITY IF THE LOW STAYS ON ITS CURRENTLY EXPECTED TRACK BUT
THIS MAY CHANGE OVER THE NEXT FEW DAYS.

MDB

&&

LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
     UNTIL 3 AM MONDAY.

     GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-
     LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-
     LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 AM MONDAY TO 9 PM
     MONDAY.

&&

$$