🚀 go-pugleaf

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1213 PM CST SAT FEB 9 2013

DISCUSSION...
1058 AM CST

SENT A QUICK UPDATE TO SHAVE A COUPLE DEGREES OFF HIGH TEMPS AND
SLOW THE CLEARING TREND THIS AFTERNOON. LOOKS LIKE NW INDIANA
SHOULD BE ABLE TO CLEAR OUT THIS AFTERNOON WITH SOME HOPE FOR SOME
PARTIAL CLEARING FOR EASTERN MOST TIER OF IL COUNTIES.

IZZI

//PREV DISCUSSION...

314 AM...MAIN FORECAST CONCERN/CHALLENGE THIS MORNING REMAINS THE
NEXT STORM SYSTEM TO AFFECT THE AREA SUNDAY...WITH A CHANCE OF
SOME LIGHT FREEZING RAIN LATE TONIGHT INTO EARLY SUNDAY MORNING...
RAIN SUNDAY...AND A WINDY MONDAY.

LOW CLOUDS REMAINED TRAPPED UNDER A STRONG INVERSION AS A LARGE
RIDGE OF HIGH PRESSURE MOVES EAST THIS MORNING. AS WINDS TURNED
MORE EASTERLY FRIDAY EVENING...CLOUDS BEGAN MOVING BACK WEST AND
NOW ARE MOVING NORTH/NORTHWEST AS WINDS TURN SOUTHEAST. SOME HOLES
HAVE DEVELOPED BUT CLOUDS TEND TO FILL/ADVECT BACK INTO THE HOLES.
GIVEN THE STRENGTH OF THE INVERSION...COULD REMAIN MOSTLY CLOUDY
FOR A GOOD PORTION OF TODAY AND HAVE TRENDED MORE PESSIMISTIC
WITH SKY COVER BUT TRENDS WILL NEED TO BE MONITORED LATER THIS
MORNING. UNDER CLEAR SKIES... DENSE FOG DEVELOPED FRIDAY EVENING
NEAR THE WI BORDER AND FAR NORTHWEST IL. AS THE CLOUDS MOVED BACK
INTO THESE AREAS...FOG LIFTED. FOG DEVELOPMENT REMAINS POSSIBLE
WHERE ANY CLEARING PERSISTS PRIOR TO SUNRISE.

EXTENT OF CLOUD COVER WILL IMPACT HIGH TEMPS TODAY WHICH THEN
COULD IMPACT LOWS/TEMP TRENDS TONIGHT. SOUTH OF THE SNOW PACK...
SOME SUN COULD EASILY PUSH TEMPS INTO THE MID/UPPER 30S AND IF
THAT WERE TO HAPPEN...INCREASING HIGH/MID LEVEL CLOUDS SHOULD PUT
THE BRAKES ON TEMPS DROPPING OFF LATER THIS EVENING THOUGH LOWS IN
THE UPPER 20S NORTH OF I-80 STILL LOOK REASONABLE...LOWER 30S
SOUTHERN CWA...THEN TEMPS SHOULD STEADY AND LIKELY BEGIN RISING A
FEW DEGREES OVERNIGHT/TOWARD MORNING. TEMP TRENDS AND HOW MUCH
ABOVE OR BELOW FREEZING THEY ARE WILL BE IMPORTANT FOR PRECIP
TYPE...SPECIFICALLY FREEZING RAIN POTENTIAL...LATE TONIGHT/SUNDAY
MORNING.

LOW PRESSURE OVER COLORADO WILL MOVE NORTHEAST ACROSS THE PLAINS
TONIGHT AND SUNDAY AS IT DEEPENS...THEN MOVE ACROSS THE NORTHERN
LAKES REGION ON MONDAY. A FAIRLY STRONG UPPER WAVE WILL MOVE
ACROSS THE AREA ON SUNDAY AND APPEARS THE BULK OF THE PRECIP WILL
FALL FROM MID MORNING THROUGH MID/LATE AFTERNOON. PRECIP DURATION
MIGHT ONLY BE A FEW HOURS AT ANY ONE LOCATION. THE POTENTIAL
PROBLEM BECOMES ANY LIGHTER PRECIP THAT DEVELOPS AHEAD OF THIS
WAVE AS STRONGER WARM AIR ADVECTION DEVELOPS DURING THE PREDAWN
HOURS SUNDAY AND PERSISTS FOR A FEW HRS AFTER SUNRISE. FORECAST
SOUNDINGS SHOW A LARGE WARM LAYER ALOFT. AS IT SATURATES...SOME
COOLING COULD PRODUCE A FEW ICE PELLETS BUT STILL APPEARS WARM
ENOUGH THAT PRECIP SHOULD BE ALL RAIN. IN ADDITION...THE LOWER
LEVELS ARE RATHER DRY. SO MUCH OF THIS LIGHTER PRECIP COULD END UP
BEING VIRGA AS THE THE COLUMN SATURATES. WITH THE UNKNOWN OF JUST
HOW WARM SURFACE TEMPS WILL BE AROUND SUNRISE...MAINLY ACROSS THE
NORTHERN HALF/THIRD OF THE CWA...AND ESPECIALLY OVER THE DEEPER
SNOW PACK ACROSS THE FAR NORTHERN CWA...THINK IT IS STILL
REASONABLE TO HAVE SOME MENTION OF CHANCE/SLIGHT CHANCE OF LIGHT
FREEZING RAIN. DURATION OF ANY FREEZING RAIN WOULD LIKELY BE SHORT
AND HAVE IT MIXED WITH RAIN IN THE GRIDS TO TRY TO CONVEY THE
UNCERTAINTY WITH TEMPS. TEMPS SHOULD QUICKLY WARM ABOVE FREEZING
BY MID MORNING...EVEN ACROSS THE FAR NORTH...ENDING THE THREAT OF
ANY FREEZING RAIN.

AS THE UPPER WAVE MOVES ACROSS THE AREA...PRECIPITABLE WATER
VALUES APPROACH 1 INCH WITH SOME IMPRESSIVE OMEGA. THIS WILL
LIKELY LEAD TO A FEW PERIODS OF MODERATE TO PERHAPS HEAVY RAIN...
A FEW RUMBLES OF THUNDER AND RAINFALL AMOUNTS APPROACHING A HALF
INCH...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. AS DEWPOINTS
INCREASE BOTH FROM THE RAIN AND ADVECTING MOISTURE NORTH...EXPECT
SOME FOG TO FORM BUT BEST CHANCE FOR ANY SIGNIFICANTLY LOWER VIS
OR DENSE FOG WOULD BE OVER THE DEEPER SNOW PACK ACROSS THE FAR
NORTHERN CWA. ONCE THIS WAVE SHIFTS EAST...APPEARS THE DRY SLOT
WILL WRAP IN ACROSS THE AREA SUNDAY EVENING. WHILE TEMPS WILL WARM
INTO THE 40S MOST AREAS BY AFTERNOON...ACTUAL DAILY HIGH TEMPS...
AND STILL IN THE 40S...PERHAPS 50ISH SOUTH...MAY BE SET IN THE
EARLY EVENING AHEAD OF THE COLDER AIR WHICH SPREADS ACROSS THE
AREA LATE SUNDAY EVENING INTO EARLY MONDAY MORNING. NOT ALL THAT
CONFIDENT HOW MUCH CLEARING THERE WILL BE...BUT ANY PRECIP AT THAT
TIME WOULD ONLY BE SOME DRIZZLE WITH PERHAPS A FEW SHOWERS STILL
LINGERING IN NORTHWEST INDIANA AND ALONG THE WI/IL BORDER. AS THE
COLDER AIR SPREADS IN...SOME DEEPER MOISTURE WITH IT WILL LIKELY
LEAD TO A FEW SNOW SHOWERS ACROSS NORTHWEST IL OVERNIGHT. THESE
SNOW SHOWERS WILL PROBABLY PERSIST INTO MONDAY WITH PERHAPS A
DUSTING OF SNOW POSSIBLE.

THE GRADIENT WILL TIGHTEN ON SUNDAY AS THE LOW DEEPENS AND HIGH
PRESSURE SLOWLY MOVES OFF THE ATLANTIC COAST. SOUTHERLY WINDS
GUSTING 30 MPH TO PERHAPS 35 MPH LOOK REASONABLE FOR SUNDAY.
SPEEDS WILL LIKELY DIMINISH SUNDAY EVENING AND SHIFT SOUTHWESTERLY
BUT AS THE COLDER AIR SPREADS OVERNIGHT BUT ESPECIALLY ON
MONDAY...STILL LOOKS QUITE WINDY WITH WESTERLY WINDS GUSTING
PERHAPS AS HIGH AS 40 MPH.

WEAK HIGH PRESSURE/RIDGING IS EXPECTED ACROSS THE SOUTHERN LAKES
TUESDAY/WEDNESDAY WHICH WILL ALLOW FOR DRY CONDITIONS. IF SUNSHINE
MATERIALIZES DURING THIS PERIOD...HIGHS LIKELY TO BE ABOVE NORMAL
WITH LOWER 40S POSSIBLE WEDNESDAY ACROSS PARTS OF THE AREA AND
PERHAPS ACROSS THE ENTIRE AREA BY THURSDAY. BUT BY THIS TIME
PERIOD...CONFIDENCE IS FAIRLY LOW. ECMWF HAS BEEN SOMEWHAT
CONSISTENT WITH A CLIPPER LIKE LOW MOVING ACROSS THE LAKES AND NOW
SLOWS AND DEEPENS THIS LOW OVER THE EASTERN LAKES INTO EARLY NEXT
WEEKEND. DOES SEEM TO BE SOME CONTINUITY ON A COLDER PATTERN INTO
NEXT WEEKEND. CMS

&&

AVIATION...

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

* MVFR CEILINGS LINGERING THIS AFTERNOON...BEFORE SCATTERING OUT
  BY LATE AFTERNOON.

* RAIN OVERSPREADING THE TERMINALS EARLY SUNDAY MORNING...WITH A
  BRIEF WINDOW OF FREEZING RAIN DURING THE MORNING...THEN ALL RAIN
  WITH TS POSSIBLE IN THE AFTERNOON.

* MVFR CONDITIONS ARRIVING BY MID MORNING SUNDAY...THEN CONTINUING
  A DOWNWARD TREND WITH IFR CONDITIONS EXPECTED BY MID DAY.

RODRIGUEZ

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

PERSISTENT STRATUS SHOULD LINGER AROUND INTO THE AFTERNOON HOURS
BEFORE FINALLY SCATTERING OUT LATER THIS AFTERNOON. THEN EXPECT A
PERIOD OF QUIETER WEATHER THIS EVENING BEFORE VFR CEILINGS SPREAD
BACK OVER THE TERMINALS TONIGHT. A SYSTEM MOVING THROUGH THE
CENTRAL PLAINS WILL SHIFT EAST/NORTHEAST TONIGHT...BRINGING RAIN
CHANCES AND LOWERING CEILINGS EARLY SUNDAY MORNING. DID MOVE UP
TIMING A BIT OF ONSET OF PRECIP EARLY SUNDAY MORNING...BUT
MAINTAINED MENTION OF A BRIEF PERIOD OF FREEZING RAIN SUNDAY
MORNING. DONT THINK THIS WILL BE ANYMORE THAN A THREE HOUR WINDOW
BEFORE TEMPS RISE ABOVE FREEZING. THEN RAIN WILL CONTINUE TO
SPREAD ACROSS THE TERMINALS BY MID MORNING INCREASING IN INTENSITY
WITH CEILINGS LOWERING. MVFR CEILINGS/VIS IN LIGHT RAIN WILL
CONTINUE THROUGH MID DAY...WITH CONDITIONS FURTHER DETERIORATING
AND IFR CEILINGS EXPECTED. EXPECT THESE CONDITIONS/RAIN TO
CONTINUE THROUGH THE REMAINDER OF THE FORECAST PERIOD. HAVE LEFT
OUT ANY MENTION OF THUNDER AT THIS TIME...BUT DOES STILL APPEAR TO
BE A POSSIBILITY GOING INTO THE AFTERNOON TIME FRAME.

RODRIGUEZ


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

* HIGH CONFIDENCE WITH CEILING TRENDS THIS AFTERNOON...MEDIUM
  CONFIDENCE OF SCATTERING BY LATE AFTERNOON.

* MEDIUM HIGH CONFIDENCE WITH TIMING OF PRECIP START SUNDAY.

* MEDIUM HIGH CONFIDENCE WITH MVFR/IFR CONDITIONS SUNDAY.

* HIGH CONFIDENCE WITH WIND SPEED/DIRECTION.

RODRIGUEZ

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

SUNDAY NIGHT...PRECIP ENDING...MVFR/IFR POSSIBLE.

MONDAY...MVFR WITH SLIGHT CHANCE LIGHT SNOW.

TUESDAY THROUGH THURSDAY...VFR.

FRIDAY...CHANCE OF SNOW...MVFR POSSIBLE.

MDB

&&

MARINE...
242 AM CST

THE BIG EAST COAST LOW OFFSHORE OF CAPE COD WILL CONTINUE TO MOVE
NORTHEASTWARD WHILE AN EXPANSIVE AREA OF HIGH PRESSURE MOVES FROM
LAKE MICHIGAN EASTWARD. THIS WILL KEEP LIGHT WINDS ACROSS THE LAKE
THIS MORNING BEFORE THEY INTENSIFY FROM THE SOUTH LATER TODAY. LOW
PRESSURE WILL DEVELOP OVER EASTERN COLORADO AND MOVE NORTHEASTWARD
INTO THE UPPER MISSISSIPPI RIVER VALLEY SUNDAY AND THEN ACROSS
NORTHERN LAKE MICHIGAN MONDAY. WARMER AIR WILL SURGE NORTHWARD
ACROSS MUCH OF THE AREA SUNDAY AHEAD OF THE LOW WHICH WILL SET UP AN
INVERSION OVER THE COLD LAKE WATERS. THIS WILL KEEP MAXIMUM GUST
POTENTIAL LIMITED AS LOW LEVEL WINDS RAMP UP BUT IT STILL APPEARS
THAT WINDS OF 30 KT WILL BE PRESENT JUST BELOW THE INVERSION BUT 35
KT GALES ARE STILL A POSSIBILITY BUT CONFIDENCE IS LIMITED IN HOW
FREQUENT GALES MIGHT BE. COLDER AIR WILL WRAP IN BEHIND THE LOW
FROM THE SOUTHWEST ON MONDAY AS LOW LEVEL WINDS INCREASE FURTHER.
THE STRONGEST WINDS ARE EXPECTED AFTER THE COLD AIR ARRIVES MONDAY
WHILE THE LOW IS CROSSING NORTHERN LAKE HURON. THIS WILL SUPPORT
40-45 KT GALES ACROSS CENTRAL AND SOUTHERN PARTS OF THE LAKE ON
MONDAY AND MONDAY EVENING. WILL HOLD OFF ON A GALE WATCH FOR NOW
GIVEN THE UNCERTAINTY FOR SUNDAY BUT HAVE HIGH CONFIDENCE IN GALES
MONDAY/MONDAY EVENING. IT DOES APPEAR THAT THERE WOULD BE A BREAK
BETWEEN ANY GALES SUNDAY AND THOSE EXPECTED MONDAY SO TWO SEPARATE
HEADLINES MAY BE NEEDED. WINDS WILL THEN GRADUALLY DIMINISH AS THE
SYSTEM EXITS LATER TUESDAY WITH QUIETER WEATHER EXPECTED THROUGH
MID WEEK. BEYOND THAT...A SERIES OF LOWS MAY CROSS THE GREAT LAKES
LATE NEXT WEEK BRINGING MODEST PERIODS OF INCREASED WIND SPEEDS
AND MORE PERSISTENT PERIODS OF NORTH TO NORTHWEST WINDS FOLLOWING
THE PASSAGE OF THESE LOWS.

MDB

&&

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

$$