🚀 go-pugleaf

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1116 AM CST SAT MAR 2 2013

DISCUSSION...
328 AM CST

FORECAST CHALLENGES THIS MORNING INCLUDE THE LAKE EFFECT SNOW
POTENTIAL THROUGH TONIGHT THEN THE COMPLEX SYSTEM PROGGED TO AFFECT
THE REGION EARLY NEXT WEEK.

RADAR IMAGERY SHOWS TYPICAL NOCTURNAL UPTICK IN LAKE EFFECT SNOW
SHOWERS TAKING PLACE WITH A COUPLE OF LOOSELY ORGANIZED BANDS OF
BANDS SEEMINGLY TRYING TO ORGANIZE...ONE OFF SE WI SHORE SOUTH TO
JUST EAST OF UGN AND THE OTHER MOVING INTO NW LAKE CO IN. BOUNDARY
LAYER FLOW SHOULD SLOWLY BACK MORE NORTHERLY AS THE MORNING GOES ON
AND INTO THE AFTERNOON WITH THE BETTER LAKE EFFECT POTENTIAL
SLOWLY PIVOTING EAST OUT OF NE IL BY MIDDAY...AND FOCUSING MORE INTO
NORTHWEST INDIANA THIS AFTERNOON AND EVENING. GENERALLY SPEAKING NOT
AN OVERLY GREAT LAKE EFFECT SET-UP WITH MARGINAL
THERMODYNAMICS...BUT CERTAINLY LOOKS ON PAR WITH YESTERDAY`S SET UP
WHICH PRODUCED A DUSTING TO LOCALLY AROUND AN INCH OF SNOW. SUPPOSE
ITS POSSIBLE THAT WE COULD SEE ISOLATED AREAS PICK UP AN INCH OR OF
SNOW TODAY NEAR THE LAKE...ESPECIALLY IN NW INDIANA. WRF-NAM DOES
SHOW MORE FAVORABLE THERMODYNAMIC SET-UP TONIGHT WITH RISING
INVERSION HEIGHTS AND INCREASING LAKE-850MB DELTA T VALUES...HOWEVER
BY THE TIME THE BETTER LAKE EFFECT BAND SETS UP TONIGHT THE THREAT
MAY HAVE SHIFTED JUST EAST OF OUR CWA INTO LAPORTE COUNTY.

SYNOPTIC STRATUS DECK IS MOVING SOUTH THIS MORNING BUT PRETTY
EXTENSIVE LAKE EFFECT PLUME SHOULD RESULT IN AREAS DOWN WIND OF THE
LAKE...EVEN FAIRLY FAR INLAND STARTING OUT THE DAY CLOUDY. AS LAKE
EFFECT PLUME SHIFTS EAST INTO INDIANA WOULD ANTICIPATE AT LEAST
PARTIAL SUNSHINE OVER MUCH OF IL PORTIONS OF CWA THIS AFTERNOON.
TEMPS WILL BE TRICKY WITH FAIRLY COLD AIR MASS IN PLACE ALONG WITH
SNOW COVER...HOWEVER LATE MARCH SUN HAS A WAY OF WARMING THINGS UP
NICELY SO WOULDNT BE SHOCKED IF DAY SHIFTS NEEDS TO MASSAGE HIGHS
UPWARD A BIT.

MODELS REALLY HAVE NOT COME AROUND TO A CONSENSUS SOLUTION YET FOR
THE EARLY NEXT WEEK SYSTEM...WITH THE ECMWF/NAM BEING NORTHERLY
OUTLIERS AND THE MAJORITY OF THE REMAINDER OF THE GUIDANCE FARTHER
SOUTH. GENERALLY HAVE OPTED TO FOLLOW THE GFS/GEM MORE CLOSELY
THROUGH TUESDAY WHICH SHOULD KEEP THE MAJORITY OF THE SNOW WEST OF
THE AREA THROUGH MONDAY MORNING WITH JUST A CHANCE OF SOME LIGHT
PRECIPITATION CREEPING INTO MAINLY WESTERN AREAS OF THE CWA MONDAY
AFTERNOON AND MONDAY NIGHT. IF PRECIP ARRIVES MONDAY PM THEN THERE
COULD BE SOME MIXED PRECIP OR EVEN RAIN DOWN SOUTH...BUT IS LOOKING
LIKE THE MORE LIKELY SCENARIO MAY BE DRY CONDITIONS FOR MUCH OF THE
CWA. DOES LOOK LIKE CLOSEST BRUSH WITH THIS SYSTEM AND BEST CHANCES
FOR ACCUMULATING SNOW FOR OUR CWA WILL COME TUESDAY...BUT KEPT POPS
MODEST AS THERE ARE A WIDE ARRAY OF POSSIBILITIES AT THIS POINT. ALL
MODELS WOULD SUGGEST A SWATH OF POTENTIALLY ADVISORY WORTHY
ACCUMULATING SNOWS WITH THE UPPER LOW MOVING ACROSS THE REGION...BUT
THE MODEL SPREAD IN WHERE THAT WILL OCCUR IS HUNDREDS OF MILES
RANGING FROM AS FAR NORTH AS WISCONSIN IN THE ECMWF TO AS FAR SOUTH
AS SOUTHERN IL WITH THE FIM WHICH ACTUALLY KEEPS OUR CWA DRY!
GFS/GEM SEEM TO BE THE MIDDLE GROUND FAVORING MAINLY OUR SOUTHERN
CWA...BUT FAR TOO EARLY TO START PUTTING OUR EGGS IN THAT BASKET
JUST YET AND HAVE OPTED TO JUST MAINTAIN CHANCE POPS UNTIL MODELS
CAN COME TO AROUND TO A MORE UNIFIED MESSAGE.

WHILE THERE IS A HUGE SPREAD IN THE DETAILS WITH RESPECT TO THE
HANDLING OF THIS VIGOROUS SHORTWAVE/CLOSED LOW EARLY IN THE
WEEK...THE MEDIUM RANGE MODELS/ENSEMBLES ARE IN PRETTY GOOD
AGREEMENT ON THE GENERAL SYNOPTIC PATTERN BY LATE NEXT WEEK WITH
DEVELOPING LONG WAVE TROUGH OVER THE WESTERN CONUS AND BUILDING
UPPER RIDGE OVER THE CENTRAL CONUS. CERTAINLY LINGERING SNOW COVER
COULD TEMPER THE WARM UP SOME...ESPECIALLY NORTHERN CWA...BUT 850MB
TEMP CORRELATIONS WITH ALL MODEL PROGGED 850MB TEMPS FOR NEXT FRIDAY
WOULD FAVOR HIGHS IN THE 50S WITH EVEN 60 POSSIBLE OVER SOUTHERN CWA
WHERE SNOW COVER IS NOT AN ISSUE. IMPACTS OF SNOW COVER...POTENTIAL
FOR UPPER LOW TO SLOW DOWN/MODEL UNCERTAINTIES...AND COLLABORATION
THRESHOLDS REQUIRE FORECAST TO REMAIN CONSERVATIVE FOR NOW...BUT FOR
ANYONE WAITING FOR A TASTE OF SPRING IT DOES LOOK LIKE THERE IS A
GLIMMER OF HOPE BY THE END OF NEXT WEEK!

IZZI

&&

AVIATION...

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

* NONE.

KJB

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

A SURFACE RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE AREA TONIGHT
INTO SUNDAY. THIS WILL CONTINUE TO RESULT IN NORTH-NORTHWEST WINDS
ACROSS THE AREA THROUGH THE AFTERNOON. LIGHTER WINDS ARE EXPECTED ON
MONDAY...WITH A GRADUAL SHIFT OUT THE EAST NORTHEAST BY EARLY SUNDAY
EVENING AS THE SURFACE RIDGE PUSHES TO THE EAST OF THE AREA LATE IN
THE PERIOD.

VFR CONDITIONS ARE EXPECTED AT ALL SITES...WITH THE EXCEPTION OF
KGYY...WHERE SOME LOWER CLOUDS AND LAKE EFFECT SNOW SHOWERS ARE
EXPECTED TO CONTINUE FOR THE NEXT FEW HOURS. HOWEVER...CONDITIONS
SHOULD IMPROVE AT GYY LATER THIS AFTERNOON AS CURRENT OBSERVATIONAL
ANALYSIS INDICATES THAT THE BETTER LOWER LEVEL CONVERGENCE
ZONE...SUPPORTIVE OF THE BETTER LAKE EFFECT SNOW...HAS SHIFTED TO
THE EAST OF KGYY.

KJB


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

* HIGH FOR ALL ELEMENTS.

KJB

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

SUNDAY NIGHT...VFR.

MONDAY...CHC SN AND MVFR...ESPECIALLY AT NIGHT.

TUESDAY...CHC SN AND IFR.

WEDNESDAY THROUGH FRIDAY...VFR.

RC

&&

MARINE...
329 AM CST

STEADY NORTH WINDS WILL DIMINISH TONIGHT AND BECOME LIGHT LATE
SUNDAY THROUGH SUNDAY NIGHT AS HIGH PRESSURE GRADUALLY BUILDS TOWARD
AND ACROSS THE LAKE. WINDS WILL THEN TURN NORTHEAST AND FRESHEN LATE
MONDAY THROUGH WEDNESDAY AFTERNOON AS LOW PRESSURE TRACKS TOWARD THE
OHIO VALLEY AND ANOTHER LARGE HIGH PRESSURE RIDGE GRADUALLY BUILDS
IN FROM THE WEST. COULD SEE A PERIOD OF 30 KT WINDS TUESDAY NIGHT
INTO WEDNESDAY MORNING.

IN THE NEARSHORE...GIVEN FULL NORTH FETCH BECOMING NORTHWEST...WAVES
WILL BE SLOW TO SUBSIDE...ESPECIALLY FOR GARY TO MI CITY ZONES. MAY
NEED TO EXTEND SMALL CRAFT HEADLINES...BUT FOR NOW WILL LEAVE
CURRENT EXPIRATION TIME AND LET DAYSHIFT ASSESS.

RC

&&

LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 AM
     SUNDAY.

     SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 9 AM SUNDAY