AREA FORECAST DISCUSSION
NWS CHICAGO IL
AFDCHI 1200 PM CST FRI JAN 3 2002
AVIATION DISCUSSION FOR 18Z TAF CYCLE
SC NOW EAST OF ALL BUT GYY TERMINAL SITES...AND JUST A FEW CU
POPPING ON STLT IMAGERY. WILL CONTINUE WITH GOING FORECAST OF
VERY GRADUALLY LOWERING CLOUDS OUT AHEAD OF THE IMPENDING
CLIPPER...WITH NO AVIATION RESTRICTIONS. LIGHT NW WIND WILL TURN
SW ON THE BACK SIDE OF THIN SURFACE RIDGE...WITH NO AVIATION
IMPACT HERE EITHER.
JHV
205 AM CST FRI JAN 3 2003
PUBLIC DISCUSSION FOR 400 AM ZONES FORECAST...
850 LOW WRN LAKE ERIE GRADUALLY PULLING OFF TO NE AND FILLING TO
OPEN TROF THIS AM. WRAPAROUND CYCLONIC FLOW KEEPING SKIES MOSTLY
CLDY ALTHO SOME BREAKS APPEARING NR RFD. ACARS DATA INDICATING
NWLY
FLOW BLO 2300 FT BUT N TO NE ABV. SO CONCERN ABT CONTD CLDS AND
FLURRIES THIS MRNG IN NWRN IN. ALL MODELS TAKING FLO TO NWLY BY
18Z
AS RIDGE IN ERN PLAINS BUILDS INTO MS VLY. PRETTY GOOD CYCLONIC
FLOW
FOR MRNG HRS TOO AND CANNOT SEE GOING SUNNY THIS AM BUT PTCLDY
AT
BEST. DEWPTS IN UPR TEENS ALREADY POURING INTO NRN IL AND
PROGGED
DOWN IN THE MID TEENS TNGT...SO DRYING IN LOW LVLS EVIDENT AS
WELL.
WUD THINK OF GOING SUNNY FOR AFTN, HOWEVER S/W DIVING DOWN 5H
FLOW
ARRIVING THIS EVE WITH CI OUTFLOW LIKELY HERE BEFORE AFTN. THIS
CLIPPER FIZZLING IN DRY AIR OVER IL IN LOWER LEVELS SO LITTLE
MORE
THAN SOME HI AC OR CI MOVING THRU TNGT.
A BRIEF RESPITE UNDER UPR RIDGE SAT MRNG AND THEN NEXT CLIPPER
ARRIVES IN THE AFTN AND EVE. THIS ONE APPEARS MORE VIGOROUS WITH
CLOSED UPR LOW DIVING ACROSS THE UPR MS VLY SAT AFTN AND RIGHT
ACROSS CWA SAT NGT. THIS MAY DEPOSIT AN INCH OR TWO ACROSS THE
CWA.
MODELS ALL AGREE WITH ENERGY AVAILABLE WITH THIS SYSTEM AND WUD
LIKE
TO WORD SNOW LIKELY FOR LT SAT AND SAT NGT BUT PLACEMENT OF
HEAVIER
SNOWFALL STILL A LITTLE NEBULOUS AND WILL LEAVE CHC POPS FOR NOW.
CYCLONIC FLOW CONTS SUNDAY AND THREAT OF LIGHT SNOW OR FLURRIES
LINGERING INTO SUN NGT WITH PASSAGE OF SEVERAL UPR TROFS AROUND
FIXED POLAR VORTEX OVER HUDSON BAY AREA. UPR RIDGE BLDG IN ON
MONDAY
AND SHUD BE DRY IF NOT FOR LAKE EFFECT SNOW SHOWERS IN NWRN IN
INTO
MON NIGHT. BUT 850 TEMPS WARMING BY TUESDAY MRNG WHILE FLOW
SWITCHING MORE NWLY. SO APPEARS DRY FOR TUESDAY BUT THREAT OF
RAIN
OR SNOW ON WED WITH FROPA...CHANGING TO SNOW WED NGT FALLING 850
TEMPS.
.CHI...NONE
RLB
AVIATION DISCUSSION FOR 00Z TAFS...
RADAR MOSAIC SHOWS MOTH-EATEN DEFORMATION ZONE SNOW STRETCHING
FROM
NORTHERN IL INTO LOWER MICHIGAN AT THIS HOUR...WITH MAIN
SYNOPTIC
SNOW ALONG AND SOUTH OF APPROXIMATELY KBMI-KIKK-KVPZ LINE.
PROBLEM
FOR TERMINAL AREAS HOWEVER REMAINS LIGHT LAKE EFFECT SNOW
SHOWERS
MOVING INLAND WITH LOW LEVEL NORTHEASTERLY FLOW. 23Z ACARS
SOUNDING
OUT OF ORD SHOWS -12 DEG C AT BASE OF INVERSION AT 840 MB...WITH
LAKE WATER TEMPS AROUND +1 DEG MAKING FOR MAGINAL 13 DEG DELTA
T.
HOWEVER...CYCLONIC AND CONVERGENT LOW LEVEL FLOW ENOUGH TO
GENERATE
LIGHT SNOW SHOWERS.
MODEL FORECASTS GRADUALLY BACK LOW LEVEL WINDS AROUND TO NORTH
AND
NORTH-NORTHWEST THROUGH TONIGHT. THEREFORE HAVE KEPT TEMPO -SHSN
WITH IFR VSBY...WITH OTHERWISE GENERALLY PREVAILING MVFR CIGS
PAST
MIDNIGHT TONIGHT. WITH SURFACE WINDS BECOMING MORE NORTHWESTERLY
BY
FRIDAY MORNING HAVE THEN ENDED -SHSN...THOUGH HAVE KEPT
GENERALLY
MVFR CIGS THROUGH THE DAY DUE TO LINGERING TRAPPED MOISTURE AND
DIURNAL STEEPENING OF LOW LEVEL LAPSE RATES SEEN IN MODEL
SOUNDINGS
BELOW SHARP INVERSION.
RATZER
...THIS IS THE 250 PM AREA FORECAST DISCUSSION...
AFDOKX WEATHER ANALYSIS...A WEAK SURFACE LOW WAS OFF THE MARYLAND/VIRGINIA
COAST. THE 6 HR MODEL FORECASTS OF THE LOW'S POSITION AND STRENGTH
ARE QUITE GOOD.
SHORT RANGE FORECAST...AS THE LOW TRACKS FURTHER WEST AND NORTH THAN
PREVIOUSLY FORECAST...EAST WINDS WILL CONTINUE TO ADVECT WARMER AIR
WEST ACROSS THE REGION.
HERE ARE MY THOUGHTS ON WARNINGS AND ADVISORIES AT THIS TIME...
BECAUSE PRECIPITATION WILL REMAIN MOSTLY AS SNOW ACROSS
ORANGE...PUTNAM...AND NORTHERN FAIRFIELD COUNTIES...I'LL CONTINUE
WITH THE WINTER STORM WARNING OVERNIGHT. 4 TO 6 INCHES OF SNOW HAS
FALLEN ACROSS ORANGE AND 3 TO 5 INCHES ACROSS PUTNAM COUNTIES
THROUGH 2 PM.
BECAUSE PRECIPITATION WILL REMAIN A MIX OF FREEZING RAIN...SLEET AND
SNOW UNTIL 00Z ACROSS PASSAIC...BERGEN...ROCKLAND AND WESTCHESTER
COUNTIES...I'LL CONTINUE THE WINTER STORM WARNING...MAINLY FOR
ICING. BUFKIT HOURLY FORECAST SOUNDINGS SUPPORT A CHANGEOVER TO
PLAIN FM 00Z TO 06Z...THEN BACK TO SNOW AFTER 06Z.
ACROSS NORTHERN NEW HAVEN AND NORTHER MIDDLESEX COUNTIES...UP TO 3
TO 4 INCHES OF SNOW HAVE ACCUMULATED. THIS TREND SHOULD CONT FOR THE
NEXT FEW HOURS...BEFORE TRANSITIONING TO A MIX OF SLEET AND RAIN. I
WILL ALSO CONT THE WINTER STORM WARNINGS HERE.
WINTER WEATHER ADVISORIES WILL BE CONTINUED ACROSS NORTHERN NEW
LONDON...SOUTHERN FAIRFIELD EAST TO SOUTHERN MIDDLESEX
COUNTIES...WHERE MIXED PRECIP WILL OCCUR INTO EARLY TONIGHT. BASED
ON WARM AIR ADVECTION...ADVISORIES WILL BE DROPPED ELSEWHERE.
COASTAL FLOODING...BASED ON THE LOW TRACKING FURTHER WEST AND NORTH
THAN PREVIOUSLY FORECAST...NE GALES WILL BECOME E GALES AND CONTINUE
TIDAL PILING. WE'LL CONTINUE THE COASTAL FLOOD WARNINGS FOR
TONIGHT'S HIGH TIDE CYCLE...AND ADD SW SUFFOLK AND THE SOUTH SHORE
OF NASSAU COUNTY TO ACCOUNT FOR EXPECTED WIDESPREAD INLAND BAY
FLOODING. TIDAL DEPARTURES UP TO 4 FT ABOVE NORMAL ARE PROJECTED
ACROSS THE WESTERN SHORES OF LI SOUND THIS EVE.
GALE WARNINGS WILL BE CONTINUED FOR ALL COASTAL WATERS.
.OKX...
CT...WINTER STORM WARNING TONIGHT...CTZ005>007.
COASTAL FLOOD WARNING TONIGHT...CTZ009.
WINTER WEATHER ADVISORY TONIGHT...CTZ008>011.
NJ...WINTER STORM WARNING TONIGHT...NJZ002>004.
WINTER WEATHER ADVISORY...NJZ005-006-011.
NY...WINTER STORM WARNING TONIGHT...NYZ067>070.
COASTAL FLOOD WARNING TONIGHT...NYZ071-073-076-077-080.
WINTER WEATHER ADVISORY TONIGHT...NYZ071>077.
MARINE...GALE WARNING TONIGHT ALL WATERS...
ANZ355-353-350-338-335-330.
$$
GC