Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/26/12
AREA FORECAST DISCUSSION...corrected
NWS TALLAHASSEE FL
1017 AM EST Mon Dec 24 2012
...The Potential for a Significant Severe Weather Outbreak (with
Damaging Winds and Possible Tornadoes) exists across the Region from
later Christmas Day into Wednesday...with a higher end "Slight Risk"
issued from the Storm Prediction Center...
.NEAR TERM [Through Tonight]...
The large scale pattern is highlighted by a longwave trough over Wrn
states and a shortwave trough exiting LWR MS Valley. In Srn stream
weak ridging persists over NE Gulf region. Weak impulses
(shortwaves) embedded in a jet streak seen on satellite moving Ewd
from TX to SE Coast. This generating mid/high clouds and apparently
virga from radar returns but also sct rain moving across mainly
coastal panhandle. At surface,above shortwave impulses have
commenced generating a meso-low across SE LA coast with ample Gulf
moisture spreading NEWD ahead of this low across WRN/Cntrl Gulf
region. Low over WRN TN Valley with cold front SWD across NRN MS to
this meso low over LA then to SE TX. Warm front extends from TN
Valley low SEWD thru Cntrl AL and into Gulf of Mex. High well of NE
FL/SE GA coast. All this reflected in local dew points that continue
to moisten especially west of the Apalachicola River, to 60-63
degrees or 20 to 25 degrees wetter than same time yesterday across
Panhandle.
During rest of today, the shortwave trough will move rapidly ESE
from LWR MS Valley into Gulf region. As a result, at surface, TN
Valley low will ride E then NEWD towards New England into tonight.
This will serve to drag trailing cold front into Wrn/Cntrl gulf
coast becoming stationary tonight and at same time allow meso low to
lift NEWD with warm front also lifting NEWD towards local area. This
combination will help to continue to evacuate much of the very dry
air which had become entrenched across our region over the weekend,
and it will spread scattered showers, and eventually some
thunderstorms across the CWA today. The best chances for rain will
be across the NW third of the region. Although current rain low top,
and the threat for strong storms today is low, peripheral influence
of the approaching shortwave, rising dew points and warming and
destabilization of warm sector especially if higher deck vacates as
implied in SE AL this morning will bring elevated and some surface
based convection and gusty winds mainly to our NW most counties
later today. RUC13 shows 180-200 j/kg here. Based on current radar
trend, will modify POP grids with higher pops for our panhandle
counties and adjacent waters. Will go with sharp 70-20% NW-SE pop
gradient. This clearly demonstrated on local WRF. Within warm
sector, temps will be warmer today with highs approaching 70 degrees
in many locations.
Tonight, strong shortwave begins to move out of SRN Plains and
sharpen SEWD. This briefly resulting in enhanced ridging over local
region allowing cold front to stall with a brief lull in the
weather yielding low pops tonight. Shwrs and tstms will commence
around sunrise as low pivots newd and isentropic lift and elevated
convection commences ahead of lifting warm front to be shortly
replaced by surface based convection (see below). Expect lows in the
low to mid 50s. Will insert fog into GRIDS ern counties after
06z..also expect fog or mist with the light rain across wrn counties
but will exclude for now from grids.
At the area beaches today, increasing onshore flow will create a
High Risk for Rip Currents along the Panhandle Coast, with a
Moderate Risk of Rip Currents at the Big Bend Beaches. A High Risk
is expected at all of our beaches that experience surf on Tuesday,
and a High Surf Advisory will likely be needed on Tuesday night into
Wednesday. A coastal flood advisory remains possible;e, however
latest guidance shows that best chance of flooding would occur at
low tide from Apalachicola to Cedar Key (The area most susceptible
to flooding) so will hold off on issuing this product.
&&
.SHORT TERM [Tuesday Through Wednesday]...After this weak low
pressure system moves through our region, a MUCH more potent Upper
Level Shortwave will begin its rapid approach from the NW. This
shortwave, which has just entered the Pacific Northwest early this
morning, will quickly dive southeastward to a position near northern
TX by Christmas morning. This Upper Low will continue to charge
eastward then northeastward through the short term period, spawning
a rapidly deepening Sfc Low which will head off to our NE later on
Christmas into at least the first half of Wednesday, eventually
sweeping a strong Cold Front through the region. This system will
produce a very highly sheared environment which will be conducive
for Severe Weather (mainly in the form of damaging wind gusts and
possible tornadoes). Although the "primary" threat for severe storms
will occur along the squall line itself on Tuesday Night into
Wednesday (where the "timing" may keep the greatest severe
probabilities just off to our west), we are still a bit concerned
for potential Discrete SuperCell development along the initial Warm
Frontal boundary, which will move through parts of the FL Panhandle
and Southeast AL on Tuesday Afternoon. It is this Warm Front (where
the low level winds will back to the E and SE) which could be the
focus of the greatest Tornadic threat. At this time, however, we
believe that the greatest threat will be just to the West of our CWA
Christmas Afternoon, but all interests are urged to keep abreast of
this rapidly developing situation and be prepared to take action if
needed.
&&
.AVIATION...
[Through 12z Tuesday] Mainly VFR conditions are expected to prevail
with southwest winds around 10 knots developing during the day with
gusts a bit higher. However, an increase in shower activity and
possibly some isolated convection is expected to develop during the
late morning and afternoon hours and spread from from NW-SE as an
upper level disturbance moves through. The greatest chances for rain
and any storms with gusty winds will be around ECP and DHN with rain
starting around 16z and tempo for tstms 18z-22z. at ABY, tstms will
probably hold off. the rain will shut off after sundown thru rest of
period except for possibly chc shra/isold tstm at DHN around 12z.
MVFR CIGs will commence around 08z with possible IFR cigs
developing near sunrise.
&&
.MARINE...Onshore winds and seas will be on the increase to high
end cautionary levels across the western legs of the coastal waters
rest of today, and moderate levels to the east ahead of a weak
approaching frontal system. This front will stall north of the
coastal waters tonight as a much stronger low pressure system begins
to develop off to our west. South to Southwest winds ahead of this
front will quickly ramp up to strong Small Craft Advisory levels, as
a squall line of showers and and thunderstorms (some strong to
severe), pushes eastward across the marine area Tuesday Night and
Wednesday. Also, a period of Gale Force winds cannot be ruled out at
this time, before winds shift to the northwest and slowly subside.
Much lighter winds and lower seas are expected by late this week.
&&
.FIRE WEATHER...
Moist and unsettled conditions are expected through the middle of
the week as a strong storm system moves through the region. Drier
air will move in behind the front, but red flag conditions are not
currently expected for the next several days.
&&
.HYDROLOGY...Much of the region is expected to receive between 1 and
2 inches of rainfall during the next few days (except around 0.5"
over the SE FL Big Bend). This may cause some minor rises along area
rivers, but due to low flows in area basins, no significant rises
are expected at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 70 55 72 59 66 / 20 20 50 60 60
Panama City 70 61 71 61 63 / 40 20 60 70 50
Dothan 69 56 70 55 59 / 50 30 80 80 50
Albany 68 53 70 56 61 / 40 20 70 80 60
Valdosta 69 52 70 57 65 / 20 10 40 60 70
Cross City 70 53 72 58 69 / 10 10 20 40 70
Apalachicola 69 60 70 63 66 / 30 20 40 60 60
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Risk of Rip Currents today along the beaches of Walton,
Bay, and Gulf Counties.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Block/Gould
SHORT TERM...Gould
AVIATION...Block
MARINE...Block
FIRE WEATHER...DVD
HYDROLOGY...Gould
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
737 PM EST TUE DEC 25 2012
..SEVERE STORMS INCLUDING A FEW TORNADOES LIKELY TONIGHT/EARLY WED
MORNING...
.UPDATE...
MAIN CONVECTIVE LINE AHEAD OF COLD FRONT IS PROGRESSING QUICKER
THAN ANTICIPATED ACROSS CENTRAL AL THIS EVENING AND ARE NOW
LOOKING AT POTENTIAL FOR SEVERE THREAT BEGINNING NEAR 03Z IN
WESTERN PORTIONS OF THE FORECAST AREA. SOME DISCRETE CELLS SHOWING
SIGNS OF ROTATION HAVE BEEN TRACKING MOSTLY NORTHWARD ACROSS
SOUTHEASTERN AL NEAR THE NORTHERN EXTENT OF THE WARM SECTOR. BASED
ON PROGGED SHORT RANGE ENSEMBLE MEMBERS... THE SOUTHWESTERN
PORTION OF CENTRAL GA LOOKS TO HAVE THE BETTER INSTABILITY
TONIGHT POTENTIALLY GETTING UP TO 500 J/KG OF MUCAPE...WHILE A
LINGERING HYBRID CAD DOME HAS PRIMARILY SERVED TO LIMIT
INSTABILITY FARTHER NORTHWARD. EARLIER SHOWER DEVELOPMENT DURING
THE DAY MAY HAVE REINFORCED THIS FEATURE AND WILL MONITOR
CONDITIONS CLOSELY. ALL CONSIDERED... BELIEVE BEST CHANCE FOR
ISOLATED TORNADO POTENTIAL WILL BE SOUTHERN/SOUTHWESTERN TIER
MAINLY SOUTH OF COLUMBUS AND MACON. MADE ADJUSTMENTS TO POP/WX
GRIDS BASED ON PROGRESSION OF AFOREMENTIONED CONVECTION.
BAKER
&&
.PREV DISCUSSION... /ISSUED 309 PM EST TUE DEC 25 2012/
SHORT TERM /TONIGHT THROUGH THURSDAY/...
INGREDIENTS STILL COMING TOGETHER FOR NOCTURNAL SEVERE WEATHER EVENT
AFTER MIDNIGHT TONIGHT. 12Z RUNS HAVE CONTINUED TREND OF MORE
FAVORABLE PARAMETERS. 0-1KM BULK SHEAR OF 45-55KT NOW IN BOTH NAM
AND GFS...THOUGH THESE ARE SOMEWHAT EAST OF BEST MOISTURE/CAPE AXIS.
IN SPITE OF THIS...FCST SIG TOR PARAMETER VALUES ARE NOW 1.5-2.5 IN
GFS AND 4-5 WITH THE NAM. TORNADO THREAT IS QUITE HIGH FOR A COOL
SEASON QLCS EVENT.
TIMING ON GFS AND ECMWF HAS SHIFTED SLIGHTLY BACK TO BETTER MATCH
THE SLOWER NAM. LATEST HRRR NOW SIMILAR TO GFS TIMING. DUE TO
UNCERTAINTY IN MODELS AND WHETHER ANY PREFRONTAL STORM ACTIVITY WILL
DEVELOP...HAVE NOT TWEAKED TIMING BACK TOO MUCH. TOTAL RAINFALL
STILL HARD PRESSED TO EXCEED 2 INCHES. NO SIGNIFICANT FLOODING
PROBLEMS EXPECTED.
AFTER FRONT PASSES...PRECIP SHOULD END QUICKLY. WILL BE ISSUING A
WIND ADVISORY FOR THE ENTIRE AREA BUT STARTING A LITTLE SOONER IN
THE MOUNTAINS AS LOW LEVEL FLOW OF 50KTS COULD MIX DOWN TO HIGHER
ELEVATIONS. ALSO HAVE CONTINUED SLT CHC/CHC RAIN/SNOW SHOWER MIX
OVER PARTS OF FAR NE GA WED NIGHT. SHOULD NOT SEE ANY ACCUMULATION.
REST OF FCST LOOKS GOOD. WE WILL CONTINUE TO MONITOR THE SITUATION.
SNELSON
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE LONG TERM PORTION OF THE FORECAST BEGINS WITH WRAP AROUND
MOISTURE FROM THE BACK SIDE OF THE EXITING LOW PRESSURE SYSTEM
ACROSS N GA. COOLER AIR WILL ALSO BE FILTERING INTO THE STATE BUT IT
LOOKS LIKE THE BETTER MOISTURE WILL STAY FAR ENOUGH NORTH THAT IT
SHOULD NOT CAUSE ANY WINTER PRECIP ACROSS THE N GA MOUNTAINS THU
NIGHT/FRIDAY MORNING. HIGH PRESSURE BUILDS IN THURSDAY WITH MOISTURE
BEGINNING TO RETURN TO THE REGION FRIDAY. MOISTURE BEGINS PUSHING IN
AHEAD OF NEXT SYSTEM WHICH WILL BRING ANOTHER ROUND OF PRECIP TO THE
STATE FRIDAY NIGHT/SATURDAY. THIS NEXT SYSTEM DOES NOT LOOK AS
STRONG AS THE ONE THAT WILL MOVE THROUGH TONIGHT...SO WILL CONTINUE
WITH ONLY SHOWERS FOR NOW. THE MODELS SHOW THIS SECOND SYSTEM MOVING
THROUGH THE AREA VERY FAST WITH THE RAIN MOVING INTO W GA AROUND 06Z
SAT AND THE ENTIRE SYSTEM EXITING THE EAST SIDE OF THE STATE BY 18Z
SAT. A STRONG HIGH PRESSURE RIDGE BUILDS IN BEHIND THIS SECOND
SYSTEM AND IT LOOKS TO KEEP NORTH AND CENTRAL GEORGIA DRY SUNDAY AND
MONDAY.
01
&&
.HYDROLOGY...
FLASH FLOOD GUIDANCE REMAINS IN THE 1.5/2.5/3.0 FOR 1H 3H 6H
GUIDANCE RESPECTIVELY. THESE ARE SLIGHTLY REDUCED VALUES WITH RECENT
RAINS BUT LIKELY NOT SUFFICIENT FOR SIGNIFICANT FLOODING CONCERNS
GIVEN INITIAL LIGHT TO MODERATE RAIN AHEAD OF SYSTEM AND THEN
RAPID MOVEMENT OF COLD FRONT ONCE CONVECTIVELY ENHANCED BANDS SET
UP. STILL WILL BE CLOSELY MONITORING THE NEXT 24 HOUR FOR ANY
SHORT FUSE RIVER AND STREAM WARNINGS PRIMARILY.
.AVIATION...
00Z UPDATE...
IFR TO NEAR HIGH END LIFR CIGS HAVE LINGERED MAINLY ACROSS THE
NORTHERN SITES THIS EVENING. HEIGHTS SHOULD IMPROVE TO MVFR LEVELS
NEAR 1500-2500 FT AFTER 03-05Z AND THEN VFR NEAR 4000 FT AFTER
17Z. AREA OF SCATTERED THUNDERSTORMS HAS BEEN PROGRESSING QUICKER
THAN ORIGINALLY ANTICIPATED ACROSS CENTRAL ALABAMA AND NOW LOOKS
TO AFFECT MOST SITES IN THE 03-09Z TIME RANGE TONIGHT. SOME -SHRA
AND POTENTIALLY ISOLATED THUNDER CAN BE EXPECTED OUT AHEAD OF THE
STORMS. THE STORMS HAVE THE POTENTIAL TO PRODUCE STRONG WINDS AND
MAY BECOME SEVERE. WINDS OF 12-18 KTS WITH GUSTS OF 20-30KTS CAN
BE EXPECTED FROM 03Z TONIGHT ONWARD AND SE WINDS SHOULD VEER TO SW
AFTER 11Z WEDNESDAY. VSBYS SHOULD GENERALLY BE 4-6 SM TONIGHT AND
POSSIBLY LOWER IN -TSRA... THEN P6SM AFTER 11Z.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON ENDING TIME FOR PRECIPITATION.
HIGH CONFIDENCE ALL ELSE.
BAKER
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 49 52 31 51 / 100 80 0 5
ATLANTA 49 49 30 49 / 100 20 0 5
BLAIRSVILLE 46 48 28 45 / 100 80 20 5
CARTERSVILLE 49 50 31 46 / 100 20 0 5
COLUMBUS 50 51 33 53 / 100 20 0 5
GAINESVILLE 47 50 31 48 / 100 60 0 5
MACON 55 55 33 54 / 100 60 0 5
ROME 48 49 32 47 / 100 20 5 5
PEACHTREE CITY 49 49 31 50 / 100 20 0 5
VIDALIA 59 60 36 56 / 80 80 0 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 10 AM TO 10 PM EST WEDNESDAY FOR THE
FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...
BLECKLEY...BUTTS...CARROLL...CHATTAHOOCHEE...CHEROKEE...CLARKE...
CLAYTON...COBB...COWETA...CRAWFORD...CRISP...DAWSON...DEKALB...
DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE...FLOYD...FORSYTH...
GLASCOCK...GREENE...GWINNETT...HALL...HANCOCK...HARALSON...
HARRIS...HEARD...HENRY...HOUSTON...JACKSON...JASPER...
JEFFERSON...JOHNSON...JONES...LAMAR...LAURENS...MACON...
MADISON...MARION...MERIWETHER...MONROE...MONTGOMERY...MORGAN...
MUSCOGEE...NEWTON...NORTH FULTON...OCONEE...OGLETHORPE...
PAULDING...PEACH...PICKENS...PIKE...POLK...PULASKI...PUTNAM...
ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART...SUMTER...
TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...
TROUP...TWIGGS...UPSON...WALTON...WARREN...WASHINGTON...
WEBSTER...WHEELER...WILCOX...WILKES...WILKINSON.
WIND ADVISORY FROM 1 AM TO 10 PM EST WEDNESDAY FOR THE FOLLOWING
ZONES: CATOOSA...CHATTOOGA...DADE...FANNIN...GILMER...GORDON...
LUMPKIN...MURRAY...TOWNS...UNION...WALKER...WHITE...WHITFIELD.
&&
$$
SHORT TERM...SNELSON/BAKER
LONG TERM....01
AVIATION...BAKER
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
138 PM EST MON DEC 24 2012
.PREV DISCUSSION... /ISSUED 1020 AM EST MON DEC 24 2012/
UPDATE...
QUICK UPDATE TO ADD TSRA TO FCST GRIDS TODAY...MAINLY OVER AREAS
ALONG AND SOUTH OF I-20. RAP MUCAPE ANALYSIS CONTINUES TO SHOW
VALUES OF 200-400 J/KG OVER THE AREA. RADAR AND NLDN CG DATA ALSO
INDICATE MOSTLY ELEVATED TSRA BUT A LITTLE MORE VIGOROUS THAN
EXPECTED. WHILE NEAR TERM THIS WILL DIMINISH AS THE WEAK SHORT
WAVE AND FRONT MOVE TO THE EAST...WILL HAVE TO INCLUDE CONVECTION
THROUGH MOST OF THE DAY. REST OF FCST LOOKS GOOD. FAVORABLE
PATTERN FOR DENSE FOG AFTER MIDNIGHT TONIGHT. HAVE TWEAKED GRIDS
FURTHER TO SHOW THIS. BETWEEN THE RAIN TODAY...DENSE FOG TONIGHT
..SHRA/TSRA XMAS DAY AND SVR QLCS EVENT TUE NIGHT/WED MORNING...
TRAVEL WILL BE NEGATIVELY IMPACTED FOR A WHILE!
MEDIA...COULD YOU PLEASE ASK RESIDENTS CHECK THE BATTERIES IN THEIR
NOAA WX RADIOS OR INSTALL A SEVERE WEATHER ALERTING APP ON THEIR
SMART PHONES? TUE NIGHT COULD BE A LONG NIGHT. THANKS.
SNELSON
PREV DISCUSSION... /ISSUED 615 AM EST MON DEC 24 2012/
SHORT TERM /TODAY THROUGH TUESDAY/...
SHORT WAVE MOVES ACROSS THE AREA TODAY AS A WEAK COLD FRONT MOVES
INTO N GA AND BECOMES STATIONARY ACROSS THE N-CENTRAL GA AREA
TONIGHT BEFORE MOVING N AS A WARM FRONT ON TUESDAY.
RAIN/SHOWERS CURRENTLY MOVING ACROSS N GA AND INTO W GA...WILL
CONTINUE ACROSS MUCH OF THE AREA TODAY...DIMINISHING DURING THE
AFTERNOON HOURS FROM W TO E. WHILE YOU CAN NOT COMPLETELY RULE OUT A
A BRIEF THUNDERSTORM...MUCAPES ARE RUNNING LESS THAN 400 AND NO
LIGHTNING HAS BEEN OBSERVED SO FAR. PASSAGE OF THE SHORT WAVE LOOKS
TO CREATE A LULL OF PRECIP POTENTIAL TONIGHT WITH ONLY SMALL CHANCES
OF LIGHT RAIN ACROSS CENTRAL GA. HOWEVER WIDESPREAD FOG IS EXPECTED
TO DEVELOP AND WE WILL NEED TO WATCH FOR POSSIBLE DENSE FOG.
AS THE NEXT SURFACE LOW PRESSURE SYSTEM MOVES ACROSS THE LOWER MS
VALLEY ON TUESDAY...RAIN/SHOWERS WILL DEVELOP ACROSS THE AREA
THROUGH THE DAY ON TUESDAY...POSSIBLY STARTING ACROSS PORTIONS OF
CENTRAL GA LATE TONIGHT. INSTABILITY IS LOW FOR TUESDAY SO
THUNDERSTORM POTENTIAL IS LOW.
FORECAST HIGH TEMPERATURES ARE RUNNING SLIGHTLY BELOW NORMAL AT AHN
TO 5 DEGREES ABOVE NORMAL AT CSG. FORECAST HIGH TEMPERATURES ARE
RUNNING 2-8 DEGREES ABOVE ON TUESDAY AND WILL BE HIGHLY DEPENDENT ON
THE RAIN AND WARM FRONT. FORECAST LOW TEMPERATURES RUNNING 7-14
DEGREES ABOVE NORMAL TONIGHT.
OVERALL CONFIDENCE IS MEDIUM TO HIGH.
BDL
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
SEVERE WEATHER LIKELY CHRISTMAS NIGHT...
EXTENDED PERIOD INITIALIZES QUITE ACTIVE FOR CHRISTMAS NIGHT WITH
THE INCREASING LIKELIHOOD OF SEVERE WX ACROSS THE AREA. A MODERATE
RISK OF SEVERE STORMS HAS NOW BEEN POSTED BY SPC WITH SLIGHT RISK
ENCOMPASSING MOST OF WEST GEORGIA FOR DAY 2. MODELS IN EXCELLENT
AGREEMENT IN SHOWING A DEVELOPING 995 LOW OVER THE TENNESSEE
VALLEY PROGRESSING NNE...LEAVING THE LOCAL AREA IN THE WARM SECTOR
BY 06Z WED WITH DEWPOINTS LIKELY IN THE UPPER 50S TO LOWER 60S.
ALTHOUGH RESULTANT CAPE VALUES WILL NOT BE AS HIGH AS LOCATIONS TO
THE WEST...EXPECT DYNAMICS OF SYSTEM ALONE INCLUDING IMPRESSIVE
DIFFLUENT PATTERN ALOFT TO COMPENSATE LACK OF CONVECTIVE FORCING.
SHEAR WILL NOT BE AN ISSUE WITH THIS SYSTEM WITH A 60 KT 850MB JET
TRAVERSING THE AREA AND 0-1KM HELICITY OF 400 M2/S2 TO 600 M2/S2.
AS IS MOST TIMES THE CASE...INSTABILITY WILL BE THE KEY AND MODELS
DO SHOW A DROP OFF AS SYSTEM MOVES THROUGH THE LOCAL AREA. FEEL AT
THIS POINT THIS WILL MEAN A LIMIT TO OVERALL EXTENT OF SEVERE
WEATHER EVENT BUT WILL NOT PRECLUDE SEVERE WEATHER ENTIRELY. IN
FACT ANY TORNADOES ABLE TO FORM WILL BE CAPABLE OF ACHIEVING F2
STATUS OR PERHAPS GREATER AND EXHIBIT LONG LIFE CYCLES GIVEN STP
OVER 2 INDICATED BY MOST MODELS. TOOK A LOOK AT THE CIPS ANALOG
SITE FOR THIS EVENT AND SEEMS MOST SIMILAR EVENTS DID PRODUCE
SEVERE WEATHER OVER THE AREA INCLUDING TORNADOES WITH THE EMPHASIS
ON THE SOUTHERN CWA.
SYSTEM PROGRESSES RAPIDLY EAST AND DISCOUNTING SLOWER NAM12 FOR
NOW AS IT SEEMS AN OUTLIER. WRAPAROUND IS VERY SHALLOW WITH THIS
SYSTEM BUT ENOUGH FORCING TO WARRANT A MIX FOR THE FIRST PART OF
WED NIGHT. NEXT SYSTEM SLATED FOR NEXT SAT WITH THE ECMWF THE MOST
AGGRESSIVE BUT BOTH MODELS TARGETING THE SOUTHERN TIER FOR
HIGHEST POPS AND HAVE CONFIGURED LONG TERM GRIDS AS SUCH.
DEESE
&&
.AVIATION...
18Z UPDATE...
MAIN PROBLEM IS IFR/LIFR CIGS/VSBYS THROUGH TUES. IFR CIGS APPEARS
LIKELY AS ONE SYSTEM MOVES AWAY BUT STRONGER SYSTEM APPROACHING
FROM THE WEST. WILL LIKELY SEE LIFR AROUND 03Z TUES MOST PLACES.
LARGE AREA OF RAIN WILL MOVE IN FROM THE SOUTH AROUND 15Z OVER
CSG/MCN AND 19Z AT ATL METRO AIRPORTS. SOME ELEVATED INSTABILITY
AGAIN DEVELOPS TONIGHT BUT LIKELIHOOD OF TSRA NOT HIGH ENOUGH TO
JUSTIFY MENTION IN TAF. MAY HAVE TO ADD TO CSG/MCN IN LATER
ISSUANCES FOR TUES AFTERNOON. SFC WINDS WILL BECOME LIGHT THEN
EAST AROUND 13-15Z THEN GRADUALLY INCREASE TO 5 TO 10KTS.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE FOR TIMING OF IFR/LIFR CIGS.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 52 41 56 49 / 100 20 100 100
ATLANTA 56 48 60 50 / 100 20 100 100
BLAIRSVILLE 49 42 55 47 / 100 20 100 100
CARTERSVILLE 56 41 58 48 / 100 20 100 100
COLUMBUS 63 52 66 52 / 80 30 100 100
GAINESVILLE 50 42 54 47 / 100 20 100 100
MACON 60 48 63 55 / 90 30 100 90
ROME 56 42 59 51 / 100 20 100 100
PEACHTREE CITY 58 43 61 49 / 100 20 100 100
VIDALIA 63 53 68 56 / 50 30 70 70
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....01
AVIATION...SNELSON
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1020 AM EST MON DEC 24 2012
.UPDATE...
QUICK UPDATE TO ADD TSRA TO FCST GRIDS TODAY...MAINLY OVER AREAS
ALONG AND SOUTH OF I-20. RAP MUCAPE ANALYSIS CONTINUES TO SHOW
VALUES OF 200-400 J/KG OVER THE AREA. RADAR AND NLDN CG DATA ALSO
INDICATE MOSTLY ELEVATED TSRA BUT A LITTLE MORE VIGOROUS THAN
EXPECTED. WHILE NEAR TERM THIS WILL DIMINISH AS THE WEAK SHORT
WAVE AND FRONT MOVE TO THE EAST...WILL HAVE TO INCLUDE CONVECTION
THROUGH MOST OF THE DAY. REST OF FCST LOOKS GOOD. FAVORABLE
PATTERN FOR DENSE FOG AFTER MIDNIGHT TONIGHT. HAVE TWEAKED GRIDS
FURTHER TO SHOW THIS. BETWEEN THE RAIN TODAY...DENSE FOG TONIGHT
...SHRA/TSRA XMAS DAY AND SVR QLCS EVENT TUE NIGHT/WED MORNING...
TRAVEL WILL BE NEGATIVELY IMPACTED FOR A WHILE!
MEDIA...COULD YOU PLEASE ASK RESIDENTS CHECK THE BATTERIES IN THEIR
NOAA WX RADIOS OR INSTALL A SEVERE WEATHER ALERTING APP ON THEIR
SMART PHONES? TUE NIGHT COULD BE A LONG NIGHT. THANKS.
SNELSON
&&
.PREV DISCUSSION... /ISSUED 615 AM EST MON DEC 24 2012/
SHORT TERM /TODAY THROUGH TUESDAY/...
SHORT WAVE MOVES ACROSS THE AREA TODAY AS A WEAK COLD FRONT MOVES
INTO N GA AND BECOMES STATIONARY ACROSS THE N-CENTRAL GA AREA
TONIGHT BEFORE MOVING N AS A WARM FRONT ON TUESDAY.
RAIN/SHOWERS CURRENTLY MOVING ACROSS N GA AND INTO W GA...WILL
CONTINUE ACROSS MUCH OF THE AREA TODAY...DIMINISHING DURING THE
AFTERNOON HOURS FROM W TO E. WHILE YOU CAN NOT COMPLETELY RULE OUT A
A BRIEF THUNDERSTORM...MUCAPES ARE RUNNING LESS THAN 400 AND NO
LIGHTNING HAS BEEN OBSERVED SO FAR. PASSAGE OF THE SHORT WAVE LOOKS
TO CREATE A LULL OF PRECIP POTENTIAL TONIGHT WITH ONLY SMALL CHANCES
OF LIGHT RAIN ACROSS CENTRAL GA. HOWEVER WIDESPREAD FOG IS EXPECTED
TO DEVELOP AND WE WILL NEED TO WATCH FOR POSSIBLE DENSE FOG.
AS THE NEXT SURFACE LOW PRESSURE SYSTEM MOVES ACROSS THE LOWER MS
VALLEY ON TUESDAY...RAIN/SHOWERS WILL DEVELOP ACROSS THE AREA
THROUGH THE DAY ON TUESDAY...POSSIBLY STARTING ACROSS PORTIONS OF
CENTRAL GA LATE TONIGHT. INSTABILITY IS LOW FOR TUESDAY SO
THUNDERSTORM POTENTIAL IS LOW.
FORECAST HIGH TEMPERATURES ARE RUNNING SLIGHTLY BELOW NORMAL AT AHN
TO 5 DEGREES ABOVE NORMAL AT CSG. FORECAST HIGH TEMPERATURES ARE
RUNNING 2-8 DEGREES ABOVE ON TUESDAY AND WILL BE HIGHLY DEPENDENT ON
THE RAIN AND WARM FRONT. FORECAST LOW TEMPERATURES RUNNING 7-14
DEGREES ABOVE NORMAL TONIGHT.
OVERALL CONFIDENCE IS MEDIUM TO HIGH.
BDL
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
.SEVERE WEATHER LIKELY CHRISTMAS NIGHT...
EXTENDED PERIOD INITIALIZES QUITE ACTIVE FOR CHRISTMAS NIGHT WITH
THE INCREASING LIKELIHOOD OF SEVERE WX ACROSS THE AREA. A MODERATE
RISK OF SEVERE STORMS HAS NOW BEEN POSTED BY SPC WITH SLIGHT RISK
ENCOMPASSING MOST OF WEST GEORGIA FOR DAY 2. MODELS IN EXCELLENT
AGREEMENT IN SHOWING A DEVELOPING 995 LOW OVER THE TENNESSEE
VALLEY PROGRESSING NNE...LEAVING THE LOCAL AREA IN THE WARM SECTOR
BY 06Z WED WITH DEWPOINTS LIKELY IN THE UPPER 50S TO LOWER 60S.
ALTHOUGH RESULTANT CAPE VALUES WILL NOT BE AS HIGH AS LOCATIONS TO
THE WEST...EXPECT DYNAMICS OF SYSTEM ALONE INCLUDING IMPRESSIVE
DIFFLUENT PATTERN ALOFT TO COMPENSATE LACK OF CONVECTIVE FORCING.
SHEAR WILL NOT BE AN ISSUE WITH THIS SYSTEM WITH A 60 KT 850MB JET
TRAVERSING THE AREA AND 0-1KM HELICITY OF 400 M2/S2 TO 600 M2/S2.
AS IS MOST TIMES THE CASE...INSTABILITY WILL BE THE KEY AND MODELS
DO SHOW A DROP OFF AS SYSTEM MOVES THROUGH THE LOCAL AREA. FEEL AT
THIS POINT THIS WILL MEAN A LIMIT TO OVERALL EXTENT OF SEVERE
WEATHER EVENT BUT WILL NOT PRECLUDE SEVERE WEATHER ENTIRELY. IN
FACT ANY TORNADOES ABLE TO FORM WILL BE CAPABLE OF ACHIEVING F2
STATUS OR PERHAPS GREATER AND EXHIBIT LONG LIFE CYCLES GIVEN STP
OVER 2 INDICATED BY MOST MODELS. TOOK A LOOK AT THE CIPS ANALOG
SITE FOR THIS EVENT AND SEEMS MOST SIMILAR EVENTS DID PRODUCE
SEVERE WEATHER OVER THE AREA INCLUDING TORNADOES WITH THE EMPHASIS
ON THE SOUTHERN CWA.
SYSTEM PROGRESSES RAPIDLY EAST AND DISCOUNTING SLOWER NAM12 FOR
NOW AS IT SEEMS AN OUTLIER. WRAPAROUND IS VERY SHALLOW WITH THIS
SYSTEM BUT ENOUGH FORCING TO WARRANT A MIX FOR THE FIRST PART OF
WED NIGHT. NEXT SYSTEM SLATED FOR NEXT SAT WITH THE ECMWF THE MOST
AGGRESSIVE BUT BOTH MODELS TARGETING THE SOUTHERN TIER FOR
HIGHEST POPS AND HAVE CONFIGURED LONG TERM GRIDS AS SUCH.
DEESE
AVIATION...
12Z UPDATE...
MAIN CONCERN WILL BE LOWERING OF CEILINGS TO IFR-MVFR LEVELS WITH
PRECIP AS IT MOVES ACROSS THE AREA TODAY. LOW CONFIDENCE FORECAST
FOR WHEN AND HOW LONG BUT POTENTIAL IS THERE. SMALL CHANCES FOR
BRIEF THUNDERSTORMS BUT NO CONFIDENCE FOR WHERE AND WHEN THEY
COULD AFFECT THE TAF SITES. SURFACE WINDS VARYING AROUND SOUTH AT
10 KTS OR LESS AND LIGHT AND VARIABLE TONIGHT. EXCELLENT POTENTIAL
FOR IFR OR LIFR CONDITIONS TONIGHT DUE TO FOG.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM TO HIGH CONFIDENCE FOR WINDS.
LOW TO MEDIUM CONFIDENCE ALL OTHER ELEMENTS.
BDL
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 52 41 56 49 / 100 20 100 100
ATLANTA 56 48 60 50 / 100 20 100 100
BLAIRSVILLE 49 42 55 47 / 100 20 100 100
CARTERSVILLE 56 41 58 48 / 100 20 100 100
COLUMBUS 63 52 66 52 / 80 30 100 100
GAINESVILLE 50 42 54 47 / 100 20 100 100
MACON 60 48 63 55 / 90 30 100 90
ROME 56 42 59 51 / 100 20 100 100
PEACHTREE CITY 58 43 61 49 / 100 20 100 100
VIDALIA 63 53 68 56 / 50 30 70 70
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....01
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
812 AM CST MON DEC 24 2012
.DISCUSSION...
334 AM CST
FORECAST CHALLENGES THIS MORNING INCLUDE PRECIP POTENTIAL
TODAY...PERSISTENT MARGINAL LAKE EFFECT SET-UP TONIGHT THROUGH
TUESDAY NIGHT...THEN THE BOXING DAY STORM PROGGED TO GIVE OUR AREA A
GLANCING BLOW (LITERALLY AND FIGURATIVELY!).
PAIR OF SHORTWAVE TROUGHS MOVING EAST THIS MORNING...ONE LOOKING
FAIRLY VIGOROUS IN SATELLITE IMAGERY OVER SOUTHERN MINNESOTA WITH
THE OTHER IN THE RED RIVER VALLEY. SOUTHERN WAVE IS PROGGED TO LIFT
ENE INTO THE OHIO VALLEY TODAY AS SOUTHERN MN VORT SLIDES ESE INTO
WI. SOME OF THE GUIDANCE SUGGESTS THAT THE NORTHERN STREAM WAVE
COULD PULL THE PRECIP WITH THE SOUTHERN STREAM NORTHWARD ENOUGH TO
CLIP OUR SE COUNTIES THIS MORNING. FARTHER NORTH DEPTH OF THE
MOISTURE IS DEFINITELY LACKING...THOUGH MODELS ARE FAIRLY INSISTENT
ON DEEPENING THE SATURATED/MOIST LAYER LATER THIS MORNING INTO THE
AFTERNOON. NOT OVERLY EXCITED ABOUT PRECIP POTENTIAL AND PLAN TO
JUST CARRY SLIGHT CHANCE OF FLURRIES OR FRDZ FOR NORTHWEST CWA.
AS THIS WAVE APPROACHES TODAY FORECAST SOUNDINGS SUGGEST THAT
INVERSION HEIGHTS WILL RISE A BIT AND SETS THE STAGE FOR A MARGINAL
LAKE EFFECT SET-UP STARTING LATER THIS AFTERNOON AND GENERALLY
CONTINUING WITH PERSISTENT NE WINDS THROUGH TUESDAY NIGHT.
LAKE-850MB DELTA-T VALUES ARE PROGGED TO BE SOMEWHAT FAVORABLE
(15-17C)...BUT INVERSION HEIGHTS ARE NOTHING TO GET TINGLY ABOUT
GENERALLY STAYING BELOW 6KFT. IN ADDITION...TEMPS AT THE TOP OF THE
LAKE INDUCED CONVECTIVE LAYER ARE ONLY PROGGED TO BE -8C TO -10C
WHICH SUGGESTS VERY LOW PROB OF ICE NUCLEI IN THE CLOUDS. SO WHAT
LAKE EFFECT PRECIP DOES FORM SHOULD NOT BE SIGNIFICANT AND PROBABLY
MORE TINY SNOW GRAINS GIVEN THE ANTICIPATED LACK OF ICE IN THE
CLOUDS. SHIP OBS AND SATELLITE DATA SUGGEST THAT LAKE SST ARE
GENERALLY IN THE MID 40S...SO WITH A WIND OFF THE LAKE AIR TEMPS
NEAR THE LAKE WILL PROBABLY HANG OUT JUST ABOVE THE FREEZING MARK
CUTTING DOWN ON CHANCE OF ANY LIGHT ACCUMS. WHILE I EXPECT THERE
WILL LIKELY BE LIGHT LAKE EFFECT PRECIP AROUND THINK THE CHANCES OF
MEASURABLE PRECIP ARE LOW AND HAVE CUT BACK ON POPS.
ATTENTION THEN TURNS TO THE POWERFUL SOUTHERN STREAM SYSTEM PROGGED
TO RESULT IN SURFACE CYCLONE SPINNING UP OVER TEXAS TUESDAY BEFORE
LIFTING NORTHEAST INTO THE UPPER OHIO VALLEY BY MIDDAY
WEDNESDAY...THEN RE-FORMING AS SECONDARY CYCLOGENESIS TAKES PLACE
ALONG THE MID ATLANTIC COAST. SYSTEM SHOULD BE ABLE TO DRAG A
FORMIDABLE SLUG OF MOISTURE NORTHWARD INTO DEVELOPING DEFORMATION
ZONE WHICH IS PROGGED TO REACH THE SE 1/3 TO 1/4 OF OUR CWA. BUFKIT
FORECAST SOUNDINGS FROM KLAF SUGGEST THAT THIS SYSTEM MAY NOT BE THE
MOST EFFICIENT SNOW PRODUCER WITH DEEP ISOTHERMAL LAYER AROUND -5C
FROM THE SURFACE TO OVER 700MB AND A FAIRLY SHALLOW FAVORABLE
DENDRITIC GROWTH LAYER. IN ADDITION...T/H CROSS SECTIONS SHOW STRONG
OMEGA WILL BE ABOVE THE MOST FAVORED SNOW GROWTH REGION.
FINALLY...SURFACE TEMPS ALSO LOOK MARGINAL AND POSSIBLY FLIRTING
WITH 32F OR JUST ABOVE OUTSIDE OF THE HEAVIER PRECIP WHICH WILL ALSO
TEND TO LIMIT ACCUMS AND BLOW-ABILITY OF THE SNOW. BASED ON CURRENT
FORECAST TRACK AND WHAT COULD BE A BIT GENEROUS 10:1 SLR USING A
CONSENSUS QPF VALUE THERE STILL LOOKS TO BE THE POTENTIAL FOR
COUPLE/FEW INCHES OF SNOW OVER FAR SE CWA WITH AMOUNTS QUICKLY
TAPERING OFF TO THE NORTHWEST. STRONG WINDS ARE LIKELY TO RESULT IN
A WIND WHIPPED SNOW AND COULD SEE THE EVENTUAL NEED FOR A FEW OF OUR
SE COUNTIES TO POTENTIAL GET A WINTER WX ADVISORY AS THE EVENT NEARS.
LAKE EFFECT/ENHANCEMENT POTENTIAL DOES EXIST ON WEDNESDAY...HOWEVER
THERMODYNAMICALLY THE SET-UP DOES NOT IMPROVE MUCH WEDNESDAY. BUT
WITH THE LIKELY ADDITION OF ICE INTO THE CLOUDS VIA MOISTURE BEING
FLUNG NORTH AROUND THE PERIPHERY OF THE OHIO VALLEY LOW AS WELL AS
SOME ADDED LARGE SCALE ASCENT FELT COMFORTABLE MAINTAINING LIKELY
POPS WEDNESDAY DOWNWIND OF THE LAKE. HOWLING NORTHEAST WIND OFF THE
UNSEASONABLY MILD LAKE WEDNESDAY COULD MAKE IT HARD FOR TEMPS TO GET
BELOW FREEZING WHICH WOULD AGAIN CUT DOWN ON OUR ACCUMULATION
POTENTIAL IN THE CITY.
SOMEWHAT UNSETTLED PATTERN LIKELY TO CONTINUE INTO THE WEEKEND WITH
ANOTHER SHORTWAVE APPROACHING FRI NIGHT INTO SATURDAY. AT THIS
DISTANCE MEDIUM RANGE MODELS ARE SHOWING THIS SYSTEM TO BE ANYTHING
TO WRITE HOME ABOUT...BUT CONSIDERING CHICAGO`S SEASONAL SNOWFALL
TOTAL IS 0.3" I SUPPOSE EVEN AN INCH MIGHT AT LEAST WORTHY OF AN
EMAIL HOME! ECMWF IS TRYING TO DRAG A SLUG OF ARCTIC AIR DOWN LATE
IN THE WEEKEND...BUT THE ECMWF HAS BEEN DOING THAT A LOT IN THE DAYS
5+ TIME FRAME ONLY TO BACK OFF ON THE INTENSITY OF THE COLD AS
"EVENT" NEARS. DIDNT MAKE ANY REAL CHANGES TO GOING FORECAST FOR THE
WEEKEND WHICH FEATURES NEAR/SLIGHT BELOW AVG TEMPS AND LITTLE PRECIP
AFTER FRI NIGHT/SAT MORNING SYSTEM PASSES BY.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* MVFR CEILINGS THROUGH THE REMAINDER OF THE DAY AND TONIGHT.
* SMALL CHANCE FOR SOME -DZ...BUT TOO SMALL A CHANCE TO INCLUDE IN
TAFS AT THIS TIME.
* NNELY WINDS BECOMING NLY THIS AFTERNOON. SPEEDS REMAINING LESS
THAN 10KT.
//DISCUSSION...UPDATED 12Z...
AN UPPER TROUGH CONTINUES TO MOVE E ACROSS MID AMERICA EARLY THIS
MORNING...LOCATED OVER THE MS VALLEY AT 11Z. WITHING THIS TROUGH
ARE TWO DISTINCT FEATURES. IN THE NORTHERN PORTION MOVING E
ACROSS THE UPPER MIDWEST IS A MID LEVEL LOW WHILE IN THE SOUTHERN
SECTION A SHORT WAVE IS MOVING E OVER THE OZARKS. THE MAIN
SURFACE FEATURE...A WEAK SURFACE LOW IN FAR WESTERN KY...IS
ASSOCIATED WITH THE SOUTHERN SHORT WAVE.
THE STRATUS/STRATOCU HAD CLEARED FROM ORD AND MDW DURING THE
PREDAWN...THOUGH BASED ON RUC13 OUTPUT WHICH HAD THE CLEARING
TREND WELL HANDLED...BRINGS THE LOW LEVEL MOISTURE BACK ACROSS
THE ORD AND MDW AREAS 16Z-17Z SO HAVE MVFR CEILINGS RETURNING
AROUND THAT TIME.
PROSPECTS FOR ANY PRECIPITATION OUTSIDE OF ANYTHING VERY LIGHT
AND INSIGNIFICANT ARE LOW. WITH A LACK OF MOISTURE FOR ABOUT 4KM
ABOVE THE LOW LEVEL MOISTURE TRAPPED UNDER THE INVERSION AND WITH
THE UPPER TROUGH PASSING OVER AND TO THE E OF THE LOCAL AREA BY
18Z HAVE ELIMINATED ALL MENTION OF PRECIPITATION FROM 12Z TAF
ISSUANCE.
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER NORTHERN ALBERTA WILL
CONTINUE TO SLOWLY BUILD S ACROSS THE PLAINS TODAY AND TONIGHT.
THIS SHOULD RESULT IN LOCAL SURFACE WINDS CURRENTLY FROM THE ENE
TO BACK TO A NNE TO N DIRECTION BY EARLY TO MID AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* LOW CONFIDENCE IN DZ CHANCES.
* MEDIUM CONFIDENCE IN CIG AND WIND DIRECTION TRENDS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...SLIGHT CHANCE OF LIGHT LAKE EFFECT SNOW AND
ASSOCIATED MVFR CIGS AND VSBYS.
WEDNESDAY...LAKE EFFECT ENHANCED SNOW LIKELY WITH ASSOCIATED IFR
CONDITIONS.
THURSDAY...VFR.
FRIDAY...VFR.
SATURDAY...CHANCE OF LIGHT SNOW WITH MVFR/OCCASIONAL IFR.
SUNDAY...VFR
TRS
&&
.MARINE...
216 AM CST
A RIDGE OF HIGH PRESSURE CENTERED OVER THE NORTHERN CANADIAN
PRAIRIE WILL CONTINUE TO BUILD S ACROSS THE NORTHERN AND CENTRAL
PLAINS TO THE LOWER MS VALLEY TODAY KEEPING A MODERATE TO FRESH
BREEZE ON THE NORTH PART OF THE LAKE THROUGH TUESDAY NIGHT.
WINDS ON THE SOUTH PORTION OF THE LAKE INCREASE TO FRESH TO
STRONG BREEZES TONIGHT AND UP TO NEAR GALE OR GALE FORCE BY
WEDNESDAY AS LOW PRESSURE DEEPENS AS IT MOVES FROM E TX TO THE
LOWER MS VALLEY TUESDAY. THE LOW THE TURNS NE TOWARD TO THE
TENNESSEE VALLEY TUESDAY NIGHT THEN MOVES EAST TO EASTERN VIRGINA
DURING WEDNESDAY.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
625 AM CST MON DEC 24 2012
.DISCUSSION...
334 AM CST
FORECAST CHALLENGES THIS MORNING INCLUDE PRECIP POTENTIAL
TODAY...PERSISTENT MARGINAL LAKE EFFECT SET-UP TONIGHT THROUGH
TUESDAY NIGHT...THEN THE BOXING DAY STORM PROGGED TO GIVE OUR AREA A
GLANCING BLOW (LITERALLY AND FIGURATIVELY!).
PAIR OF SHORTWAVE TROUGHS MOVING EAST THIS MORNING...ONE LOOKING
FAIRLY VIGOROUS IN SATELLITE IMAGERY OVER SOUTHERN MINNESOTA WITH
THE OTHER IN THE RED RIVER VALLEY. SOUTHERN WAVE IS PROGGED TO LIFT
ENE INTO THE OHIO VALLEY TODAY AS SOUTHERN MN VORT SLIDES ESE INTO
WI. SOME OF THE GUIDANCE SUGGESTS THAT THE NORTHERN STREAM WAVE
COULD PULL THE PRECIP WITH THE SOUTHERN STREAM NORTHWARD ENOUGH TO
CLIP OUR SE COUNTIES THIS MORNING. FARTHER NORTH DEPTH OF THE
MOISTURE IS DEFINITELY LACKING...THOUGH MODELS ARE FAIRLY INSISTENT
ON DEEPENING THE SATURATED/MOIST LAYER LATER THIS MORNING INTO THE
AFTERNOON. NOT OVERLY EXCITED ABOUT PRECIP POTENTIAL AND PLAN TO
JUST CARRY SLIGHT CHANCE OF FLURRIES OR FRDZ FOR NORTHWEST CWA.
AS THIS WAVE APPROACHES TODAY FORECAST SOUNDINGS SUGGEST THAT
INVERSION HEIGHTS WILL RISE A BIT AND SETS THE STAGE FOR A MARGINAL
LAKE EFFECT SET-UP STARTING LATER THIS AFTERNOON AND GENERALLY
CONTINUING WITH PERSISTENT NE WINDS THROUGH TUESDAY NIGHT.
LAKE-850MB DELTA-T VALUES ARE PROGGED TO BE SOMEWHAT FAVORABLE
(15-17C)...BUT INVERSION HEIGHTS ARE NOTHING TO GET TINGLY ABOUT
GENERALLY STAYING BELOW 6KFT. IN ADDITION...TEMPS AT THE TOP OF THE
LAKE INDUCED CONVECTIVE LAYER ARE ONLY PROGGED TO BE -8C TO -10C
WHICH SUGGESTS VERY LOW PROB OF ICE NUCLEI IN THE CLOUDS. SO WHAT
LAKE EFFECT PRECIP DOES FORM SHOULD NOT BE SIGNIFICANT AND PROBABLY
MORE TINY SNOW GRAINS GIVEN THE ANTICIPATED LACK OF ICE IN THE
CLOUDS. SHIP OBS AND SATELLITE DATA SUGGEST THAT LAKE SST ARE
GENERALLY IN THE MID 40S...SO WITH A WIND OFF THE LAKE AIR TEMPS
NEAR THE LAKE WILL PROBABLY HANG OUT JUST ABOVE THE FREEZING MARK
CUTTING DOWN ON CHANCE OF ANY LIGHT ACCUMS. WHILE I EXPECT THERE
WILL LIKELY BE LIGHT LAKE EFFECT PRECIP AROUND THINK THE CHANCES OF
MEASURABLE PRECIP ARE LOW AND HAVE CUT BACK ON POPS.
ATTENTION THEN TURNS TO THE POWERFUL SOUTHERN STREAM SYSTEM PROGGED
TO RESULT IN SURFACE CYCLONE SPINNING UP OVER TEXAS TUESDAY BEFORE
LIFTING NORTHEAST INTO THE UPPER OHIO VALLEY BY MIDDAY
WEDNESDAY...THEN RE-FORMING AS SECONDARY CYCLOGENESIS TAKES PLACE
ALONG THE MID ATLANTIC COAST. SYSTEM SHOULD BE ABLE TO DRAG A
FORMIDABLE SLUG OF MOISTURE NORTHWARD INTO DEVELOPING DEFORMATION
ZONE WHICH IS PROGGED TO REACH THE SE 1/3 TO 1/4 OF OUR CWA. BUFKIT
FORECAST SOUNDINGS FROM KLAF SUGGEST THAT THIS SYSTEM MAY NOT BE THE
MOST EFFICIENT SNOW PRODUCER WITH DEEP ISOTHERMAL LAYER AROUND -5C
FROM THE SURFACE TO OVER 700MB AND A FAIRLY SHALLOW FAVORABLE
DENDRITIC GROWTH LAYER. IN ADDITION...T/H CROSS SECTIONS SHOW STRONG
OMEGA WILL BE ABOVE THE MOST FAVORED SNOW GROWTH REGION.
FINALLY...SURFACE TEMPS ALSO LOOK MARGINAL AND POSSIBLY FLIRTING
WITH 32F OR JUST ABOVE OUTSIDE OF THE HEAVIER PRECIP WHICH WILL ALSO
TEND TO LIMIT ACCUMS AND BLOW-ABILITY OF THE SNOW. BASED ON CURRENT
FORECAST TRACK AND WHAT COULD BE A BIT GENEROUS 10:1 SLR USING A
CONSENSUS QPF VALUE THERE STILL LOOKS TO BE THE POTENTIAL FOR
COUPLE/FEW INCHES OF SNOW OVER FAR SE CWA WITH AMOUNTS QUICKLY
TAPERING OFF TO THE NORTHWEST. STRONG WINDS ARE LIKELY TO RESULT IN
A WIND WHIPPED SNOW AND COULD SEE THE EVENTUAL NEED FOR A FEW OF OUR
SE COUNTIES TO POTENTIAL GET A WINTER WX ADVISORY AS THE EVENT NEARS.
LAKE EFFECT/ENHANCEMENT POTENTIAL DOES EXIST ON WEDNESDAY...HOWEVER
THERMODYNAMICALLY THE SET-UP DOES NOT IMPROVE MUCH WEDNESDAY. BUT
WITH THE LIKELY ADDITION OF ICE INTO THE CLOUDS VIA MOISTURE BEING
FLUNG NORTH AROUND THE PERIPHERY OF THE OHIO VALLEY LOW AS WELL AS
SOME ADDED LARGE SCALE ASCENT FELT COMFORTABLE MAINTAINING LIKELY
POPS WEDNESDAY DOWNWIND OF THE LAKE. HOWLING NORTHEAST WIND OFF THE
UNSEASONABLY MILD LAKE WEDNESDAY COULD MAKE IT HARD FOR TEMPS TO GET
BELOW FREEZING WHICH WOULD AGAIN CUT DOWN ON OUR ACCUMULATION
POTENTIAL IN THE CITY.
SOMEWHAT UNSETTLED PATTERN LIKELY TO CONTINUE INTO THE WEEKEND WITH
ANOTHER SHORTWAVE APPROACHING FRI NIGHT INTO SATURDAY. AT THIS
DISTANCE MEDIUM RANGE MODELS ARE SHOWING THIS SYSTEM TO BE ANYTHING
TO WRITE HOME ABOUT...BUT CONSIDERING CHICAGO`S SEASONAL SNOWFALL
TOTAL IS 0.3" I SUPPOSE EVEN AN INCH MIGHT AT LEAST WORTHY OF AN
EMAIL HOME! ECMWF IS TRYING TO DRAG A SLUG OF ARCTIC AIR DOWN LATE
IN THE WEEKEND...BUT THE ECMWF HAS BEEN DOING THAT A LOT IN THE DAYS
5+ TIME FRAME ONLY TO BACK OFF ON THE INTENSITY OF THE COLD AS
"EVENT" NEARS. DIDNT MAKE ANY REAL CHANGES TO GOING FORECAST FOR THE
WEEKEND WHICH FEATURES NEAR/SLIGHT BELOW AVG TEMPS AND LITTLE PRECIP
AFTER FRI NIGHT/SAT MORNING SYSTEM PASSES BY.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* RETURN OF MVFR CEILINGS
* POTENTIAL FOR LIGHT PRECIPITATION THIS MORNING
TRS
//DISCUSSION...UPDATED 12Z...
AN UPPER TROUGH CONTINUES TO MOVE E ACROSS MID AMERICA EARLY THIS
MORNING...LOCATED OVER THE MS VALLEY AT 11Z. WITHING THIS TROUGH
ARE TWO DISTINCT FEATURES. IN THE NORTHERN PORTION MOVING E
ACROSS THE UPPER MIDWEST IS A MID LEVEL LOW WHILE IN THE SOUTHERN
SECTION A SHORT WAVE IS MOVING E OVER THE OZARKS. THE MAIN
SURFACE FEATURE...A WEAK SURFACE LOW IN FAR WESTERN KY...IS
ASSOCIATED WITH THE SOUTHERN SHORT WAVE.
THE STRATUS/STRATOCU HAD CLEARED FROM ORD AND MDW DURING THE
PREDAWN...THOUGH BASED ON RUC13 OUTPUT WHICH HAD THE CLEARING
TREND WELL HANDLED...BRINGS THE LOW LEVEL MOISTURE BACK ACROSS
THE ORD AND MDW AREAS 16Z-17Z SO HAVE MVFR CEILINGS RETURNING
AROUND THAT TIME.
PROSPECTS FOR ANY PRECIPITATION OUTSIDE OF ANYTHING VERY LIGHT
AND INSIGNIFICANT ARE LOW. WITH A LACK OF MOISTURE FOR ABOUT 4KM
ABOVE THE LOW LEVEL MOISTURE TRAPPED UNDER THE INVERSION AND WITH
THE UPPER TROUGH PASSING OVER AND TO THE E OF THE LOCAL AREA BY
18Z HAVE ELIMINATED ALL MENTION OF PRECIPITATION FROM 12Z TAF
ISSUANCE.
A LARGE RIDGE OF HIGH PRESSURE CENTERED OVER NORTHERN ALBERTA WILL
CONTINUE TO SLOWLY BUILD S ACROSS THE PLAINS TODAY AND TONIGHT.
THIS SHOULD RESULT IN LOCAL SURFACE WINDS CURRENTLY FROM THE ENE
TO BACK TO A NNE TO N DIRECTION BY EARLY TO MID AFTERNOON.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
*MEDIUM CONFIDENCE ALL FORECAST ELEMENTS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...SLIGHT CHANCE OF LIGHT LAKE EFFECT SNOW AND
ASSOCIATED MVFR CIGS AND VSBYS.
WEDNESDAY...LAKE EFFECT ENHANCED SNOW LIKELY WITH ASSOCIATED IFR
CONDITIONS.
THURSDAY...VFR.
FRIDAY...VFR.
SATURDAY...CHANCE OF LIGHT SNOW WITH MVFR/OCCASIONAL IFR.
SUNDAY...VFR
TRS
&&
.MARINE...
216 AM CST
A RIDGE OF HIGH PRESSURE CENTERED OVER THE NORTHERN CANADIAN
PRAIRIE WILL CONTINUE TO BUILD S ACROSS THE NORTHERN AND CENTRAL
PLAINS TO THE LOWER MS VALLEY TODAY KEEPING A MODERATE TO FRESH
BREEZE ON THE NORTH PART OF THE LAKE THROUGH TUESDAY NIGHT.
WINDS ON THE SOUTH PORTION OF THE LAKE INCREASE TO FRESH TO
STRONG BREEZES TONIGHT AND UP TO NEAR GALE OR GALE FORCE BY
WEDNESDAY AS LOW PRESSURE DEEPENS AS IT MOVES FROM E TX TO THE
LOWER MS VALLEY TUESDAY. THE LOW THE TURNS NE TOWARD TO THE
TENNESSEE VALLEY TUESDAY NIGHT THEN MOVES EAST TO EASTERN VIRGINA
DURING WEDNESDAY.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
811 PM EST TUE DEC 25 2012
.UPDATE...
OBSERVATION/MODEL TRENDS CONT TO SUPPORT SNOW AND STRONG WINDS
CAUSING BLOWING AND DRIFTING SNOW MAINLY ACROSS SE 1/2 OF CWA WED
AS STRONG LOW OVER MS THIS EVE LIFTS NE TO VA BY WED EVE. LEADING
EDGE OF PRECIP ASSOCIATED WITH THE LOW WAS LIFTING NORTH INTO SRN
KY/SE MO ATTM... A LITTLE QUICKER THAN INDICATED BY LATEST MODEL
QPFS... BUT STILL PLENTY FAR ENOUGH AWAY FROM OUR CWA TO REMOVE
SLIGHT CHC POPS FOR THIS EVE IN THE GRIDS... WITH SNOW MENTION NOW
CONFINED TO AFT 06Z. OTRWS NO CHANGES TO AFTN FCST PLANNED THIS
EVE.
&&
.PREV DISCUSSION... /ISSUED 618 PM EST TUE DEC 25 2012/
AVIATION.../00Z TAFS/
STRONG LOW OVER WRN MS EXPECTED TO MOVE NE TO WV/VA BY 00Z THU.
SNOW ASSOCIATED WITH THIS SYSTEM SHOULD REACH FWA AROUND 12Z WED
AND CONT THROUGH THE DAY. STRONG NE WINDS WILL CAUSE BLOWING AND
DRIFTING OF THE SNOW. COMBINATION SHOULD RESULT IN AVIATION
CONDITIONS LOWERING TO LIFR AT FWA BY 15Z AND CONTG THROUGH THE
DAY WITH SOME PERIODS OF VLIFR PSBL. SNOW EXPECTED TO MOVE INTO
SBN AROUND 18Z AND CONT THROUGH 00Z THU. SNOW SHOULD BE LIGHTER AT
SBN THAN FWA... BUT PRBLY SUFFICIENTLY HEAVY FOR IFR FLIGHT
CONDITIONS. UNTIL SNOW BEGINS EXPECT SCT-BKN CLOUDS AROUND 3KFT
WITH NO VSBY RESTRICTIONS AND NE WINDS GRDLY INCRSG.
PREV DISCUSSION... /ISSUED 406 PM EST TUE DEC 25 2012/
SHORT TERM...
TONIGHT THROUGH WEDNESDAY NIGHT...
SIGNIFICANT WINTER STORM TO IMPACT MUCH OF THE CWA IN THE SHORT
TERM. WATER VAPOR IMAGERY SHOWING POTENT UPPER LOW DIGGING THROUGH
TEXAS. 12Z RAOB AND LATEST RAP ANALYSIS HAS 100KT+ UPPER JET COMING
INTO THE BASE OF THE TROUGH. ASSOCIATED SFC LOW NEAR TX/LA BORDER AT
18Z AND IS EXPECTED TO LIFT NE INTO THE CENTRAL TN VALLEY BY 12Z
WED. GOOD ISENT ASCENT AHEAD OF THIS SYSTEM ALONG THE 290-295K SFC
IS EXPECTED TO INITIATE PRECIP IN THE FAR SOUTHERN CWA AFTER
MIDNIGHT TONIGHT WITH LARGE SCALE FORCING TO INTENSIFY PRECIP TO
MOD-HVY SNOW AFTER 12Z. DESPITE A TREND TO A MORE SE TRACK...GOOD
DEFORMATION AXIS STILL SETS UP OVER SE CWA ALONG WITH SUBSTANTIAL
HEIGHT FALLS IN A DEEP MOISTURE COLUMN TO SUPPORT A WINDOW OF
OPPORTUNITY FOR WARNING CRITERIA SNOWFALL. STRONG GRADIENT BRINGING
15 TO 25 MPH WINDS WITH GUSTS TO 30 MPH LENDS FURTHER CREDENCE IN
MAINTAINING WINTER STORM WARNING. HAD TRANSITIONED REMAINING
COUNTIES IN THE WATCH OVER TO AN ADVISORY WITH GENERALLY 1-3/2-4
INCH AMOUNTS BUT ALSO ACCOMPANIED BY GUSTY WINDS FOR BLOWING SNOW.
POTENTIAL FOR MOD-HVY SNOW WILL BE SHORT-LIVED HOWEVER AS SYSTEM
WILL QUICKLY EXIT TOWARD THE EAST COAST WEDNESDAY NIGHT.
LONG TERM...
THURSDAY THROUGH TUESDAY...THE CHALLENGES THIS PERIOD INCLUDE
CHANCES FOR SNOW WITH THE PASSAGE OF A WEAK UPPER TROF LATE THIS
WEEK. ALSO...HIGH AND LOW TEMPERATURES WITH AN EXTENDED PERIOD OF
COLD AIR AND SNOW COVER OVER AT LEAST PART OF THE FORECAST AREA WILL
PROVIDE ADDITIONAL CHALLENGES. FOR THIS PACKAGE...FAVORED THE GFS.
THE GFS HAS AT LEAST AS GOOD OF RUN TO RUN CONSISTENCY AS THE ECMWF
AND APPEARS TO BE HANDLING THIS PATTERN REASONABLY WELL. THE GFS
TIMING OF THE SYSTEM LATE THIS WEEK HAS ALSO BEEN CONSISTENT FOR THE
PAST 8 RUNS AND APPEARS ON TRACK. ALSO...THE OPERATION MOS AND
ENSEMBLE MOS HAS BEEN RELATIVELY STABLE IN ITS OUTPUT FOR SEVERAL
DAYS AND APPEARS IN LINE. HAVE MODIFIED HIGH AND LOW TEMPS GIVEN
SNOW FIELD CONSIDERATIONS.
AT THE START OF THE PERIOD...DOWNWARD MOTION WILL HAVE INCREASED
SIGNIFICANTLY AS EVIDENCE OF NET ISENTROPIC ADIABATIC OMEGA WITH A
DRYING OF THE MID LEVELS. AS A RESULT...HAVE REMOVED LINGERING
FLURRIES THURSDAY OVER NW OHIO. FOR THE REST OF THE PERIOD...TRIED
TO PUT SOME DETAIL IN THE TIMING OF THE UPPER LEVEL TROF THIS
WEEKEND AND SUBSEQUENT LAKE EFFECT SNOW SHOWERS. THERE IS LITTLE
MOISTURE TO WORK WITH AND FORCING IS WEAK...SO ANY SNOW AMOUNTS
SHOULD BE LIGHT. LAKE EFFECT PARAMETERS ARE VERY MARGINAL WITH A
LIMITED FETCH. DELTA T VALUES GENERALLY SHOULD BE 10 TO 14 WITH LOW
INVERSION HEIGHTS. REMOVED THE CHANCE FOR SNOW SUNDAY AND SUNDAY
NIGHT. GFS BUFKIT PROFILE SUPPORTS FREEZING DRIZZLE OVER SNOW GIVEN
THE LACK OF ICE INDUCED IN THE CLOUD LAYER. TEMPERATURES IN A DEEP
LAYER WARM ABOVE -10C. NOT OPTIMISTIC ABOUT SNOW CHANCES MONDAY...
BUT FOR THE SAKE OF CONSISTENCY AND LINGERING UNCERTAINTY ABOUT
EARLY NEXT WEEK...LEFT LAKE EFFECT SNOW SHOWERS IN THE FORECAST
MONDAY.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ009.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR INZ018-
025>027-032>034.
WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ005>008.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
INZ015>017-020-022>024.
MI...WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR MIZ079>081.
OH...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR OHZ001-002-004-005.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR OHZ015-
016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THURSDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JAL
LONG TERM...SKIPPER
AVIATION/UPDATE...JT
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
618 PM EST TUE DEC 25 2012
.AVIATION.../00Z TAFS/
STRONG LOW OVER WRN MS EXPECTED TO MOVE NE TO WV/VA BY 00Z THU.
SNOW ASSOCIATED WITH THIS SYSTEM SHOULD REACH FWA AROUND 12Z WED
AND CONT THROUGH THE DAY. STRONG NE WINDS WILL CAUSE BLOWING AND
DRIFTING OF THE SNOW. COMBINATION SHOULD RESULT IN AVIATION
CONDITIONS LOWERING TO LIFR AT FWA BY 15Z AND CONTG THROUGH THE
DAY WITH SOME PERIODS OF VLIFR PSBL. SNOW EXPECTED TO MOVE INTO
SBN AROUND 18Z AND CONT THROUGH 00Z THU. SNOW SHOULD BE LIGHTER AT
SBN THAN FWA... BUT PRBLY SUFFICIENTLY HEAVY FOR IFR FLIGHT
CONDITIONS. UNTIL SNOW BEGINS EXPECT SCT-BKN CLOUDS AROUND 3KFT
WITH NO VSBY RESTRICTIONS AND NE WINDS GRDLY INCRSG.
&&
.PREV DISCUSSION... /ISSUED 406 PM EST TUE DEC 25 2012/
SHORT TERM...
TONIGHT THROUGH WEDNESDAY NIGHT...
SIGNIFICANT WINTER STORM TO IMPACT MUCH OF THE CWA IN THE SHORT
TERM. WATER VAPOR IMAGERY SHOWING POTENT UPPER LOW DIGGING THROUGH
TEXAS. 12Z RAOB AND LATEST RAP ANALYSIS HAS 100KT+ UPPER JET COMING
INTO THE BASE OF THE TROUGH. ASSOCIATED SFC LOW NEAR TX/LA BORDER AT
18Z AND IS EXPECTED TO LIFT NE INTO THE CENTRAL TN VALLEY BY 12Z
WED. GOOD ISENT ASCENT AHEAD OF THIS SYSTEM ALONG THE 290-295K SFC
IS EXPECTED TO INITIATE PRECIP IN THE FAR SOUTHERN CWA AFTER
MIDNIGHT TONIGHT WITH LARGE SCALE FORCING TO INTENSIFY PRECIP TO
MOD-HVY SNOW AFTER 12Z. DESPITE A TREND TO A MORE SE TRACK...GOOD
DEFORMATION AXIS STILL SETS UP OVER SE CWA ALONG WITH SUBSTANTIAL
HEIGHT FALLS IN A DEEP MOISTURE COLUMN TO SUPPORT A WINDOW OF
OPPORTUNITY FOR WARNING CRITERIA SNOWFALL. STRONG GRADIENT BRINGING
15 TO 25 MPH WINDS WITH GUSTS TO 30 MPH LENDS FURTHER CREDENCE IN
MAINTAINING WINTER STORM WARNING. HAD TRANSITIONED REMAINING
COUNTIES IN THE WATCH OVER TO AN ADVISORY WITH GENERALLY 1-3/2-4
INCH AMOUNTS BUT ALSO ACCOMPANIED BY GUSTY WINDS FOR BLOWING SNOW.
POTENTIAL FOR MOD-HVY SNOW WILL BE SHORT-LIVED HOWEVER AS SYSTEM
WILL QUICKLY EXIT TOWARD THE EAST COAST WEDNESDAY NIGHT.
LONG TERM...
THURSDAY THROUGH TUESDAY...THE CHALLENGES THIS PERIOD INCLUDE
CHANCES FOR SNOW WITH THE PASSAGE OF A WEAK UPPER TROF LATE THIS
WEEK. ALSO...HIGH AND LOW TEMPERATURES WITH AN EXTENDED PERIOD OF
COLD AIR AND SNOW COVER OVER AT LEAST PART OF THE FORECAST AREA WILL
PROVIDE ADDITIONAL CHALLENGES. FOR THIS PACKAGE...FAVORED THE GFS.
THE GFS HAS AT LEAST AS GOOD OF RUN TO RUN CONSISTENCY AS THE ECMWF
AND APPEARS TO BE HANDLING THIS PATTERN REASONABLY WELL. THE GFS
TIMING OF THE SYSTEM LATE THIS WEEK HAS ALSO BEEN CONSISTENT FOR THE
PAST 8 RUNS AND APPEARS ON TRACK. ALSO...THE OPERATION MOS AND
ENSEMBLE MOS HAS BEEN RELATIVELY STABLE IN ITS OUTPUT FOR SEVERAL
DAYS AND APPEARS IN LINE. HAVE MODIFIED HIGH AND LOW TEMPS GIVEN
SNOW FIELD CONSIDERATIONS.
AT THE START OF THE PERIOD...DOWNWARD MOTION WILL HAVE INCREASED
SIGNIFICANTLY AS EVIDENCE OF NET ISENTROPIC ADIABATIC OMEGA WITH A
DRYING OF THE MID LEVELS. AS A RESULT...HAVE REMOVED LINGERING
FLURRIES THURSDAY OVER NW OHIO. FOR THE REST OF THE PERIOD...TRIED
TO PUT SOME DETAIL IN THE TIMING OF THE UPPER LEVEL TROF THIS
WEEKEND AND SUBSEQUENT LAKE EFFECT SNOW SHOWERS. THERE IS LITTLE
MOISTURE TO WORK WITH AND FORCING IS WEAK...SO ANY SNOW AMOUNTS
SHOULD BE LIGHT. LAKE EFFECT PARAMETERS ARE VERY MARGINAL WITH A
LIMITED FETCH. DELTA T VALUES GENERALLY SHOULD BE 10 TO 14 WITH LOW
INVERSION HEIGHTS. REMOVED THE CHANCE FOR SNOW SUNDAY AND SUNDAY
NIGHT. GFS BUFKIT PROFILE SUPPORTS FREEZING DRIZZLE OVER SNOW GIVEN
THE LACK OF ICE INDUCED IN THE CLOUD LAYER. TEMPERATURES IN A DEEP
LAYER WARM ABOVE -10C. NOT OPTIMISTIC ABOUT SNOW CHANCES MONDAY...
BUT FOR THE SAKE OF CONSISTENCY AND LINGERING UNCERTAINTY ABOUT
EARLY NEXT WEEK...LEFT LAKE EFFECT SNOW SHOWERS IN THE FORECAST
MONDAY.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ009.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR INZ018-
025>027-032>034.
WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ005>008.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
INZ015>017-020-022>024.
MI...WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR MIZ079>081.
OH...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR OHZ001-002-004-005.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR OHZ015-
016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THURSDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JAL
LONG TERM...SKIPPER
AVIATION...JT
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
100 AM EST MON DEC 24 2012
.AVIATION... /06 UTC TAFS/
WEAK FRONTAL SYSTEM TO EJECT FM CNTL ARKANSAS THROUGH THE OHIO
VALLEY TODAY...AND INTO SERN OHIO BY MON EVENING. WEAK
FORCING/MOISTURE PROFILES TO PRECLUDE SIG PRECIP ACCUM.
HOWEVER...ANTICIPATE CIGS TO LWR TO BLO FUEL ALT BY MID AFTERNOON.
BEST LLVL MOISTURE FOR RAIN...POSSIBLY MIXED WITH SNOW ACRS NERN
IN/KFWA...WITH CIGS LKLY CONTG TO DETERIORATE INTO IFR RANGE AS
COLDER AIR DEEPENS IN WAKE OF SYSTEM THIS EVENING. NEAR
KSBN...AMOUNT OF LIFT MAY PROVE TOO WEAK FOR PRECIP DEVELOPMENT...
THOUGH PROFILES TO SUPPORT LIGHT FROZEN PRECIP SHOULD IT
EXTEND/DEVELOP FARTHER NW.
&&
.PREV DISCUSSION... /ISSUED 338 PM EST SUN DEC 23 2012/
SHORT TERM.../TONIGHT THROUGH MONDAY NIGHT/
LATEST SFC ANALYSIS HAS WEAK FRONTAL BOUNDARY JUST TO THE SOUTH
OF THE CWA EXTENDING BACK TO DEVELOPING FRONTAL WAVE IN EASTERN
OKLAHOMA. WATER VAPOR IMAGERY ALONG WITH LATEST RAP ANALYSIS
DEPICTING SPLIT FLOW PATTERN ACROSS THE EASTERN TWO THIRDS OF THE
CONUS...EACH WITH THEIR OWN WEAK DISTURBANCE THAT WILL MOVE ACROSS
THE REGION ON MONDAY. NORTHERN STREAM SHORT WAVE CURRENTLY MOVING
THROUGH THE DAKOTAS IS EXPECTED TO CONTINUE EASTWARD INTO THE
GREAT LAKES REGION WHILE SOUTHERN STREAM SHORT WAVE WILL MOVE INTO
THE TN VALLEY. MODEL TRENDS HAVE CONTINUED TOWARD A LACK OF
PHASING WITH THESE DISTURBANCES...RESULTING IN CONCERN OVER
FORCING AND AVAILABLE MOISTURE WITH PRECIP CHANCES MONDAY.
CONSENSUS FAVORS A SPLIT OVER OUR CWA IN BOTH MOISTURE AND
DYNAMICS AS WEAKER SOUTHERN STREAM MOVES QUICKLY INTO EAST TN BY
MONDAY AFTERNOON WHILE NORTHERN STREAM WAVE DIGS INTO THE CENTRAL
GREAT LAKES REGION AND WILL PROVIDE SOME DECENT FORCING IN OUR NE
CWA WITH 500MB HT FALLS OF 60-80M POSSIBLE. PROBLEM IS THAT BEST
MOISTURE WILL BE CONFINED TO THE NORTH. HAVE THEREFORE OPTED TO
KEEP POPS IN HIGH CHANCE RANGE IN EASTERN THIRD OF CWA WHERE BEST
CHANCE FOR PRECIP WILL MATERIALIZE. PRECIP TYPE WILL ALSO COME
INTO PLAY FOR THE E/SE CWA AS TEMPS EXPECTED TO REACH THE MID 30S
AND TIMING OF SYSTEM HAS BEST CHANCE FOR PRECIP AT MAX HEATING.
THIS WILL ALL ACT TO HOLD ANY ACCUMULATING SNOW IN CHECK WITH LESS
THAN AN INCH OVER THE NORTHERN CWA. SYSTEM QUICKLY EXITS THE
REGION MONDAY NIGHT...MAY GET CLIPPED WITH BRIEF LAKE EFFECT IN
ITS WAKE IN FAR NW CORNER BEFORE FLOW BECOMES MORE NE AND SHIFTS ANY
BANDS WEST OF THE AREA.
LONG TERM.../TUESDAY THROUGH SATURDAY/
FOCUS OF THE EXTENDED FORECAST WILL BE ON THE POTENTIAL OF SNOWFALL
ACROSS THE AREA WEDNESDAY.
FORECAST PERIOD BEGINS TUESDAY WILL QUASI ZONAL FLOW ACROSS GREAT
LAKES REGION IN ADVANCE OF SHARPENING H5 TROF AND DEEPENING SFC LOW
ACROSS WRN TX. RAISED HI TEMPS ACROSS THE SOUTHERN 3/4THS OF THE
AREA TUESDAY SLIGHTLY...AND RAISED LOWS SLIGHTLY ON TUESDAY
NIGHT...OTHERWISE NO MAJOR CHANGES TO FORECAST. H5 CUT OFF LOW WILL
DEVELOP OVER ARKLATEX REGION LATE TUESDAY AS UPPER TROF BECOMES
NEGATIVELY TILTED AND EJECTS NORTHEASTWARD THROUGH THE MID
MISSISSIPPI VALLEY INTO THE OHIO VALLEY BY WEDNESDAY. THE EXACT
TRACK OF THE SYSTEM WILL HAVE HUGE IMPLICATIONS FOR SNOWFALL AMOUNTS
ACROSS OUR AREA.
DECENT SPREAD BETWEEN DIFFERENT MODEL SYSTEM TRACKS...NOT TO BE
UNEXPECTED 72+ HOURS OUT. 12Z NAM AND 09Z/15Z SREF ARE FURTHEST NW
W/ SFC LOW TRACK INVOF CINCINNATI...WHILE THE 00Z/12Z ECMWF IS
FURTHER SE WITH A JACKSON KY TO CHARLESTON WV SFC LOW TRACK. THE 12Z
GFS/GEFS IS A NICE COMPROMISE AMONG THE SOLUTIONS...WITH A FRANKFORT
KY TO CHILLICOTHE OH TRACK. OVERALL...RECENT MODEL TRENDS HAVE
SUBTLY SHIFTED THE SYSTEM TRACK NW WITH A SLIGHTLY SLOWER
SOLUTION...WHICH IS NOT UNCOMMON WITH NEGATIVELY TILTED PANHANDLE
HOOK TYPE SYSTEMS.
A LEAN TOWARD A 12Z GFS/GEFS LOW TRACK WOULD BRING THE POTENTIAL FOR
SIGNIFICANT SNOWFALL ACROSS A PORTION OF THE AREA...WITH BROAD
SATURATED ASCENT IN THE NW QUADRANT OF THE SYSTEM. THERMAL PROFILES
WOULD BE CONDUCIVE FOR ALL SNOW WITH THE ONSET OF THE SYSTEM FOR THE
DURATION OF THE EVENT. HOWEVER...A FURTHER NW SOLUTION OR STRONGER
SYSTEM COULD WRAP WARMER AIR INTO SE PORTIONS OF THE AREA AND IN
TURN MIXED PRECIPITATION POTENTIAL. THERE IS ALSO SOME EVIDENCE FOR
HEAVIER BANDED PRECIPITATION ACROSS A PORTION OF THE AREA. STRONG
H75-H6 FRONTOGENESIS...WITH NEAR ZERO OR NEGATIVE EPV ALOFT...AND
STRONG OMEGA IMPINGING ON THE DGZ WOULD SUGGEST INGREDIENTS FOR A
POSSIBLE BAND OF HEAVY SNOWFALL...HOWEVER GIVEN UNCERTAINTIES THIS
FAR OUT...CAN NOT RESOLVE THIS IN THE FORECAST AT THIS TIME. INITIAL
THINKING IS THAT A WIDESPREAD 2-4" EVENT...WITH LOWEST AMOUNTS
WEST/NW...WITH THE POTENTIAL FOR A NARROW BAND OF 4-6" WITH LOCALLY
HIGHER AMOUNTS SOMEWHERE ACROSS THE CENTRAL TO EASTERN/SOUTHEASTERN
PORTION OF THE AREA. CONTEMPLATED A WINTER STORM WATCH WITH THIS
FCST ISSUANCE...BUT DECIDED TO DEFER TO THE NEXT SHIFT TO CAPTURE
LATEST MODEL TRENDS AND POTENTIAL INCREASED CONFIDENCE.
FORECAST WISE...INCREASED POPS WEST/NWWARD WITH GIVEN MODEL
SOLUTIONS LATE TUESDAY NIGHT THROUGH WEDNESDAY...WITH A PERIOD OF
CAT POPS FAR SE WEDNESDAY. LEFT EXPECTED PTYPE ALL SNOW AT THIS
JUNCTURE GIVEN PREFERRED MODEL SOLUTION/TRACK/INTENSITY.
SYSTEM WILL EXIT THE REGION WEDNESDAY NIGHT INTO THURSDAY. SOME
POTENTIAL FOR LIGHT LAKE EFFECT SNOW THURSDAY INTO THURSDAY NIGHT
ACROSS FAR NW PORTIONS OF THE AREA WITH NORTHERLY FLOW IN THE WAKE
OF THIS SYSTEM. OTHERWISE CONDITIONS WILL BE DRY WITH COOLER
TEMPS...ESPECIALLY EAST WITH EXPECTED FRESH SNOWPACK. LOWS THURSDAY
NIGHT COULD DROP INTO THE LOWER TEENS EAST.
NEXT SYSTEM OF INTEREST WILL ARRIVE FRIDAY NIGHT INTO SATURDAY.
ECMWF AND GFS DISAGREE WITH THE OVERALL EVOLUTION OF THE
SYSTEM...BUT BOTH HAVE THE GENERAL IDEA AND IMPACT ON OUR AREA.
ECMWF SEPARATES THE NORTHERN AND SOUTHERN STREAM ENERGY...ALLOWING
FOR SHARPENING TROUGH AND LEE CYCLOGENESIS...SIMILAR TO MIDWEEK
PANHANDLE HOOK SYSTEM. GFS HOWEVER COMBINES BOTH NORTHERN AND
SOUTHERN STREAM ENERGY WITH BROAD UPPER TROF OVER ERN CONUS AND MORE
SUBTLE SHORTWAVE. NEVERTHELESS...TEMPERATURE PROFILES SUPPORT AN ALL
SNOW TYPE EVENT.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...JAL
LONG TERM...NG
AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
548 PM CST TUE DEC 25 2012
...UPDATED TO ALLOW THE WINTER WEATHER ADVISORY TO EXPIRE...
.UPDATE...
ISSUED AT 544 PM CST TUE DEC 25 2012
RADAR AND SURFACE OBSERVATIONS STILL INDICATING THAT SOME LIGHT
SNOW/FLURRIES ARE CONTINUING ACROSS PORTIONS OF WESTERN KANSAS AS
OF 2330Z. THIS AREA SEEMS TO RELATE WELL WITH AN AREA ON MOISTURE
AND FRONTOGENESIS AROUND THE 700MB LEVEL BASED ON THE LATEST RAP.
THIS AREA OF MOISTURE AND LIFT WILL SHIFT OUT OF WESTERN KANSAS BY
03Z AS AN UPPER LEVEL TROUGH BEGINS TO CROSS THE CENTRAL HIGH
PLAINS. LITTLE IF ANY ADDITION ACCUMULATION IS EXPECTED FROM THIS
BAND OVER THE NEXT FEW HOURS SO WILL ALLOW THE WINTER WEATHER
ADVISORY EXPIRE.
&&
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 314 PM CST TUE DEC 25 2012
CLOUDS WILL DECREASE THIS EVENING AS THE STORM SYSTEM FROM THIS
MORNING MOVES INTO THE MISSISSIPPI VALLEY. A RIDGE OF HIGH PRESSURE
QUICKLY MOVES INTO WESTERN KANSAS TONIGHT ALLOWING NORTHERLY WINDS
TO BECOME LIGHT AND VARIABLE BY MIDNIGHT. VERY COLD TEMPERATURES ARE
IN STORE TONIGHT WITH LOWS DROPPING INTO THE SINGLE DIGITS WITH A
FEW AREAS ACROSS WEST CENTRAL KANSAS IN THE NEGATIVE SINGLE DIGITS.
WITH LIGHT WINDS, WIND CHILLS SHOULD REMAIN AROUND THE ACTUAL
TEMPERATURE.
MID LEVEL MOISTURE RETURNS TOMORROW AFTERNOON AS AN UPPER LEVEL
SHORTWAVE TROUGH MOVES INTO THE DESERT SOUTHWEST. THIS WILL ALLOW
MID AND HIGH CLOUDS TO INCREASE ACROSS WESTERN KANSAS IN THE
AFTERNOON. OTHERWISE EXPECT PARTLY CLOUDY SKIES AND DRY CONDITIONS.
LEE TROUGHING WILL DEVELOP ACROSS EASTERN COLORADO AND SHIFT THE
WINDS TO THE SOUTH. HIGHS TOMORROW ARE ONLY FORECASTED TO REACH TO
THE UPPER TEENS AND LOWER 20S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 345 PM CST TUE DEC 25 2012
WEDNESDAY NIGHT THROUGH FRIDAY:
TEMPERATURES WILL BE THE PRIMARY CHALLENGE IN THE FORECAST FOR THIS
PERIOD. THE NEXT UPPER AIR DISTURBANCE WILL MOVE ACROSS THE
CENTRAL/NORTHERN ROCKIES INTO THE ADJACENT WESTERN PLAINS OF THE
DAKOTAS AND NEBRASKA LATE WEDNESDAY NIGHT INTO THURSDAY. THE
RESULTING LEE TROUGH DEVELOPMENT ACROSS COLORADO AND WYOMING WILL
LEAD TO A WIND SHIFT TO THE SOUTHEAST. MINIMUM TEMPS THURSDAY
MORNING WILL BE A BIT OF A CHALLENGE AND WILL REALLY DEPEND ON HOW
MUCH MID LEVEL CLOUD THERE IS AHEAD OF THE UPPER TROUGH AND HOW
STRONG THE SURFACE WINDS WILL BE. WILL HEDGE ON CLOUDS AND WINDS
AFFECTING NOCTURNAL TEMPS ENOUGH TO KEEP THEM FROM FALLING BELOW THE
LOWER TEENS PRETTY MUCH EVERYWHERE ACROSS THE SOUTHWEST KS REGION.
ALL THE MODELS SHOW AN 850MB LOW TRACKING SLOWLY FROM EAST-CENTRAL
COLORADO TO CENTRAL KANSAS BY THURSDAY EVENING. NORTHEAST OF THE
850MB LOW...THE MODELS CONTINUE TO GENERATE SOME VERY LIGHT QPF
WHERE SATURATION WILL EXIST DUE TO SUSTAINED WEAK LIFTING AND
ALREADY CHILLY LOW LEVEL TEMPERATURES BROUGHT IN FROM THE PREVIOUS
STORM SYSTEM. THE FORECAST SOUNDING SHOW A SHALLOW MOIST LAYER, SO
ANY PRECIPITATION SHOULD BE IN THE FORM OF FLURRIES OR VERY LIGHT
SNOW...AND WILL CONTINUE TO CARRY 15-20 POPS MAINLY NORTH OF HIGHWAY
96 DURING THE DAY THURSDAY UNTIL THE 850MB LOW MOVES EAST OF THE
AREA. THE OVERALL 500MB HEIGHT PATTERN WILL EVOLVE INTO AN
ELONGATED, POSITIVELY-TILTED TROUGH AXIS FROM THE DESERT SOUTHWEST
REGION INTO MINNESOTA, WHICH IS AN UNFAVORABLE ORIENTATION FOR
PRECIPITATION. IT IS, HOWEVER, A FAVORABLE ORIENTATION FOR KEEPING
COLD AIR LOCKED IN PLACE. THE MODELS MAY BE STRUGGLING WITH THE
DEGREE OF COLD AIR AND HAVE LOWERED TEMPERATURES THURSDAY (IN THE
NORTH), THURSDAY NIGHT, AND FRIDAY (FRIDAY FORECAST HIGHS NOW MAINLY
LOWER TO MID 20S FOR MUCH OF SOUTHWEST AND WEST-CENTRAL KANSAS).
SATURDAY THROUGH TUESDAY:
YET ANOTHER FAIRLY SIGNIFICANT TROUGH WILL BE DEVELOPING ACROSS THE
WESTERN CONUS THIS UPCOMING WEEKEND. BETWEEN THIS TROUGH AND THE
EXITING THURSDAY-FRIDAY TROUGH...SHORTWAVE RIDGING WILL PREVAIL
ACROSS THE GREAT PLAINS. A COLD SURFACE HIGH WILL BE IN CONTROL
ACROSS THE PLAINS WITH SOME SLOW MODIFICATION OF THE COLD CANADIAN
AIRMASS SATURDAY (HIGHS REBOUNDING INTO THE 30S). AS THE NEW WESTERN
TROUGH BEGINS TO TAKE SHAPE SATURDAY NIGHT AND SUNDAY...PRESSURES
WILL LOWER ACROSS THE HIGH PLAINS OF COLORADO AND WYOMING WITH WINDS
SHIFTING AROUND TO THE SOUTH ONCE AGAIN. SUNDAY COULD BE FAIRLY WARM
COMPARED TO WHAT WE HAVE BEEN EXPERIENCING OF LATE...WITH HIGHS
EXPECTED TO BE IN THE LOWER TO MID 40S FOR MOST OF SOUTHERN KANSAS.
MONDAY AND TUESDAY OF NEXT WEEK ARE STILL WAY UP IN THE AIR
REGARDING EVENTUAL OUTCOME OF THE DEEP TROUGH ACROSS THE SOUTHWEST
STATES. SOME MODELS AND ENSEMBLE MEMBERS OF THE GEFS AND CANADIAN
WANT TO DEVELOP A ROBUST CLOSED LOW OVER ARIZONA OR NORTHERN
MEXICO/BAJA CALIFORNIA...AND PRETTY MUCH KEEP IT IN PLACE
EFFECTIVELY CUT OFF FROM THE MAIN POLAR WESTERLIES MUCH FARTHER
NORTH. THERE ARE A FEW MODELS (LIKE THE ECMWF AND DETERMINISTIC GFS)
THAT WANT TO KEEP SOME CONNECTION WITH THE POLAR WESTERLIES AND
SLOWLY MIGRATE LOW TOWARD THE SOUTHERN HIGH PLAINS...CREATING LOW
LEVEL RESPONSE ACROSS WEST TEXAS AND A SLUG OF GULF MOISTURE
ADVANCING NORTHWARD THROUGH TEXAS AND OKLAHOMA. THIS SCENARIO WOULD
YIELD FAIRLY SIGNIFICANT PRECIPITATION ACROSS THE SOUTHERN
PLAINS...PERHAPS REACHING FAR SOUTHERN KANSAS. IF THIS LOW DOES NOT
CUT OFF OR TRACKS FARTHER NORTH ACROSS NEW MEXICO IN A MORE NEUTRAL
ORIENTATION (VERSUS POSITIVELY-TILTED), THEN WE WILL HAVE TO THINK
ABOUT A PRECIPITATION EVENT FOR SOUTHWEST KANSAS. AS OF RIGHT NOW,
THOUGH, THIS SEEMS LIKE A LOW PROBABILITY, SO MONDAY-TUESDAY IS DRY
IN THE FORECAST. THIS MAY CHANGE IN FUTURE FORECAST UPDATES OF A
MORE NORTHERN TREND IS SEEN IN SUBSEQUENT MODEL RUNS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 510 PM CST TUE DEC 25 2012
GUSTY NORTH WINDS WILL SUBSIDE AFTER SUNSET. THE WIND WILL BECOME
LIGHT BY MIDNIGHT AS AN AREA OF HIGH PRESSURE AT THE SURFACE
BUILDS INTO WESTERN KANSAS. SUBSIDENCE IS EXPECTED TO DEVELOP
OVERNIGHT AS AN UPPER LEVEL SHORTWAVE RIDGE AXIS BUILDS INTO THE
CENTRAL PLAINS. THE LINGERING FLURRIES ACROSS WESTERN KANSAS WILL
END BY 03Z AND A CLEARING TREND WILL THEN BEGIN. 18Z NAM BUFR
SOUNDINGS DO SUGGEST THAT FOG WILL BE POSSIBLE AT DDC AND GCK
TOWARDS DAYBREAK. GUIDANCE AND HRRR DOES NOT INDICATE MORNING FOG
AT THIS TIME, BUT BASED ON THE LATEST BUFR SOUNDINGS DID GO AHEAD
AND INSERT SOME MVFR VSBYS AFTER 9Z AT DDC AND GCK.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 1 21 11 31 / 10 0 10 10
GCK -1 21 12 28 / 10 0 10 10
EHA 3 26 14 37 / 0 0 10 10
LBL 2 24 14 35 / 10 0 0 0
HYS 0 19 10 27 / 10 0 20 20
P28 7 22 13 32 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BURGERT
SHORT TERM...HOVORKA_42
LONG TERM...UMSCHEID
AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
520 PM CST TUE DEC 25 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 314 PM CST TUE DEC 25 2012
CLOUDS WILL DECREASE THIS EVENING AS THE STORM SYSTEM FROM THIS
MORNING MOVES INTO THE MISSISSIPPI VALLEY. A RIDGE OF HIGH PRESSURE
QUICKLY MOVES INTO WESTERN KANSAS TONIGHT ALLOWING NORTHERLY WINDS
TO BECOME LIGHT AND VARIABLE BY MIDNIGHT. VERY COLD TEMPERATURES ARE
IN STORE TONIGHT WITH LOWS DROPPING INTO THE SINGLE DIGITS WITH A
FEW AREAS ACROSS WEST CENTRAL KANSAS IN THE NEGATIVE SINGLE DIGITS.
WITH LIGHT WINDS, WIND CHILLS SHOULD REMAIN AROUND THE ACTUAL
TEMPERATURE.
MID LEVEL MOISTURE RETURNS TOMORROW AFTERNOON AS AN UPPER LEVEL
SHORTWAVE TROUGH MOVES INTO THE DESERT SOUTHWEST. THIS WILL ALLOW
MID AND HIGH CLOUDS TO INCREASE ACROSS WESTERN KANSAS IN THE
AFTERNOON. OTHERWISE EXPECT PARTLY CLOUDY SKIES AND DRY CONDITIONS.
LEE TROUGHING WILL DEVELOP ACROSS EASTERN COLORADO AND SHIFT THE
WINDS TO THE SOUTH. HIGHS TOMORROW ARE ONLY FORECASTED TO REACH TO
THE UPPER TEENS AND LOWER 20S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 345 PM CST TUE DEC 25 2012
WEDNESDAY NIGHT THROUGH FRIDAY:
TEMPERATURES WILL BE THE PRIMARY CHALLENGE IN THE FORECAST FOR THIS
PERIOD. THE NEXT UPPER AIR DISTURBANCE WILL MOVE ACROSS THE
CENTRAL/NORTHERN ROCKIES INTO THE ADJACENT WESTERN PLAINS OF THE
DAKOTAS AND NEBRASKA LATE WEDNESDAY NIGHT INTO THURSDAY. THE
RESULTING LEE TROUGH DEVELOPMENT ACROSS COLORADO AND WYOMING WILL
LEAD TO A WIND SHIFT TO THE SOUTHEAST. MINIMUM TEMPS THURSDAY
MORNING WILL BE A BIT OF A CHALLENGE AND WILL REALLY DEPEND ON HOW
MUCH MID LEVEL CLOUD THERE IS AHEAD OF THE UPPER TROUGH AND HOW
STRONG THE SURFACE WINDS WILL BE. WILL HEDGE ON CLOUDS AND WINDS
AFFECTING NOCTURNAL TEMPS ENOUGH TO KEEP THEM FROM FALLING BELOW THE
LOWER TEENS PRETTY MUCH EVERYWHERE ACROSS THE SOUTHWEST KS REGION.
ALL THE MODELS SHOW AN 850MB LOW TRACKING SLOWLY FROM EAST-CENTRAL
COLORADO TO CENTRAL KANSAS BY THURSDAY EVENING. NORTHEAST OF THE
850MB LOW...THE MODELS CONTINUE TO GENERATE SOME VERY LIGHT QPF
WHERE SATURATION WILL EXIST DUE TO SUSTAINED WEAK LIFTING AND
ALREADY CHILLY LOW LEVEL TEMPERATURES BROUGHT IN FROM THE PREVIOUS
STORM SYSTEM. THE FORECAST SOUNDING SHOW A SHALLOW MOIST LAYER, SO
ANY PRECIPITATION SHOULD BE IN THE FORM OF FLURRIES OR VERY LIGHT
SNOW...AND WILL CONTINUE TO CARRY 15-20 POPS MAINLY NORTH OF HIGHWAY
96 DURING THE DAY THURSDAY UNTIL THE 850MB LOW MOVES EAST OF THE
AREA. THE OVERALL 500MB HEIGHT PATTERN WILL EVOLVE INTO AN
ELONGATED, POSITIVELY-TILTED TROUGH AXIS FROM THE DESERT SOUTHWEST
REGION INTO MINNESOTA, WHICH IS AN UNFAVORABLE ORIENTATION FOR
PRECIPITATION. IT IS, HOWEVER, A FAVORABLE ORIENTATION FOR KEEPING
COLD AIR LOCKED IN PLACE. THE MODELS MAY BE STRUGGLING WITH THE
DEGREE OF COLD AIR AND HAVE LOWERED TEMPERATURES THURSDAY (IN THE
NORTH), THURSDAY NIGHT, AND FRIDAY (FRIDAY FORECAST HIGHS NOW MAINLY
LOWER TO MID 20S FOR MUCH OF SOUTHWEST AND WEST-CENTRAL KANSAS).
SATURDAY THROUGH TUESDAY:
YET ANOTHER FAIRLY SIGNIFICANT TROUGH WILL BE DEVELOPING ACROSS THE
WESTERN CONUS THIS UPCOMING WEEKEND. BETWEEN THIS TROUGH AND THE
EXITING THURSDAY-FRIDAY TROUGH...SHORTWAVE RIDGING WILL PREVAIL
ACROSS THE GREAT PLAINS. A COLD SURFACE HIGH WILL BE IN CONTROL
ACROSS THE PLAINS WITH SOME SLOW MODIFICATION OF THE COLD CANADIAN
AIRMASS SATURDAY (HIGHS REBOUNDING INTO THE 30S). AS THE NEW WESTERN
TROUGH BEGINS TO TAKE SHAPE SATURDAY NIGHT AND SUNDAY...PRESSURES
WILL LOWER ACROSS THE HIGH PLAINS OF COLORADO AND WYOMING WITH WINDS
SHIFTING AROUND TO THE SOUTH ONCE AGAIN. SUNDAY COULD BE FAIRLY WARM
COMPARED TO WHAT WE HAVE BEEN EXPERIENCING OF LATE...WITH HIGHS
EXPECTED TO BE IN THE LOWER TO MID 40S FOR MOST OF SOUTHERN KANSAS.
MONDAY AND TUESDAY OF NEXT WEEK ARE STILL WAY UP IN THE AIR
REGARDING EVENTUAL OUTCOME OF THE DEEP TROUGH ACROSS THE SOUTHWEST
STATES. SOME MODELS AND ENSEMBLE MEMBERS OF THE GEFS AND CANADIAN
WANT TO DEVELOP A ROBUST CLOSED LOW OVER ARIZONA OR NORTHERN
MEXICO/BAJA CALIFORNIA...AND PRETTY MUCH KEEP IT IN PLACE
EFFECTIVELY CUT OFF FROM THE MAIN POLAR WESTERLIES MUCH FARTHER
NORTH. THERE ARE A FEW MODELS (LIKE THE ECMWF AND DETERMINISTIC GFS)
THAT WANT TO KEEP SOME CONNECTION WITH THE POLAR WESTERLIES AND
SLOWLY MIGRATE LOW TOWARD THE SOUTHERN HIGH PLAINS...CREATING LOW
LEVEL RESPONSE ACROSS WEST TEXAS AND A SLUG OF GULF MOISTURE
ADVANCING NORTHWARD THROUGH TEXAS AND OKLAHOMA. THIS SCENARIO WOULD
YIELD FAIRLY SIGNIFICANT PRECIPITATION ACROSS THE SOUTHERN
PLAINS...PERHAPS REACHING FAR SOUTHERN KANSAS. IF THIS LOW DOES NOT
CUT OFF OR TRACKS FARTHER NORTH ACROSS NEW MEXICO IN A MORE NEUTRAL
ORIENTATION (VERSUS POSITIVELY-TILTED), THEN WE WILL HAVE TO THINK
ABOUT A PRECIPITATION EVENT FOR SOUTHWEST KANSAS. AS OF RIGHT NOW,
THOUGH, THIS SEEMS LIKE A LOW PROBABILITY, SO MONDAY-TUESDAY IS DRY
IN THE FORECAST. THIS MAY CHANGE IN FUTURE FORECAST UPDATES OF A
MORE NORTHERN TREND IS SEEN IN SUBSEQUENT MODEL RUNS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 510 PM CST TUE DEC 25 2012
GUSTY NORTH WINDS WILL SUBSIDE AFTER SUNSET. THE WIND WILL BECOME
LIGHT BY MIDNIGHT AS AN AREA OF HIGH PRESSURE AT THE SURFACE
BUILDS INTO WESTERN KANSAS. SUBSIDENCE IS EXPECTED TO DEVELOP
OVERNIGHT AS AN UPPER LEVEL SHORTWAVE RIDGE AXIS BUILDS INTO THE
CENTRAL PLAINS. THE LINGERING FLURRIES ACROSS WESTERN KANSAS WILL
END BY 03Z AND A CLEARING TREND WILL THEN BEGIN. 18Z NAM BURF
SOUNDINGS DO SUGGEST THAT FOG WILL BE POSSIBLE AT DDC AND GCK
TOWARDS DAYBREAK. GUIDANCE AND HRRR DOES NOT INDICATE MORNING FOG
AT THIS TIME, BUT BASED ON THE LATEST BUFR SOUNDINGS DID GO AHEAD
AND INSERT SOME MVFR VSBYS AFTER 9Z AT DDC AND GCK.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 1 21 11 31 / 10 0 10 10
GCK -1 21 12 28 / 10 0 10 10
EHA 3 26 14 37 / 0 0 10 10
LBL 2 24 14 35 / 10 0 0 0
HYS 0 19 10 27 / 10 0 20 20
P28 7 22 13 32 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING
FOR KSZ043>045-061>064-074>081-084>090.
&&
$$
SHORT TERM...HOVORKA_42
LONG TERM...UMSCHEID
AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS PADUCAH KY
920 PM CST TUE DEC 25 2012
.UPDATE...
ISSUED AT 920 PM CST TUE DEC 25 2012
ONLY A SLIGHT SOUTHEASTWARD ADJUSTMENT WILL BE MADE TO THE
HEAVY SNOW AXIS. IT WILL BE DIFFICULT TO SEE THE ADJUSTMENTS TO
THE GENERAL FORECAST PRODUCTS. AT THIS POINT THERE IS NOT
MUCH REASON TO KEEP HANGING OUT FOR EACH NEW MODEL RUN TO
GET CUTE WITH TOTALS. A SUMMATION OF SOLUTIONS OF THE PAST
SEVERAL DAYS IN ESSENCE YIELDS THE BEST AXIS ALONG AND JUST NORTH
AND WEST OF THE OHIO UP TOWARD THE WABASH RIVER VALLEY REGION
WITH AMOUNTS TAPERING OFF CONSIDERABLY HEADING EAST ACROSS
WEST KENTUCKY. WEST KENTUCKY WILL CONTINUE TO BE THE REAL
CHALLENGE REGION WHERE AMOUNTS...SOMEWHERE WILL TAPER DOWN
CONSIDERABLY. NO CHANGES TO THE BLIZZARD WARNING EITHER.
EARLY ONSET PRECIPITATION HAS BEEN A MIX OF RAIN...SLEET AND
SNOW. AREAS FROM ALONG THE OHIO NORTH AND WEST INTO SEMO AND
SRN IL WILL TRANSITION QUICKLY TO SNOW AS THE UPPER SYSTEM
EJECTS NE...AND THE PRECIP SHIELD SEEN OVER ARKANSAS EXPANDS
NORTH AND EAST INTO THE REGION. NEEDLESS TO SAY...CONDITIONS
WILL DETERIORATE RAPIDLY FROM SW TO NE ACROSS THE REGION
FROM 10 PM ON INTO THE OVERNIGHT...MAKING TRAVEL CONDITIONS
DANGEROUS...LIFE THREATENING. BLOWING SNOW AND DRIFTS AS
WELL WITH THE STRONG AND GUSTY WINDS.
..NOLES..
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE NEAR TERM...AN INTENSIFYING BAND OF MIXED PRECIPITATION IS
LIFTING NORTHWARD FROM NORTHERN ARKANSAS AS OF 20Z. THIS BAND IS
ASSOCIATED WITH STRONG WARM ADVECTION ON EASTERLY FLOW IN THE
850/700 MB LAYER. RUC MODEL BRINGS THE ZONE OF STRONG MID LEVEL
WARM ADVECTION AND ASSOCIATED PRECIP INTO SOUTHEAST MISSOURI BY
00Z. PRECIP TYPE WILL GRADUALLY CHANGE TO SNOW BY MID EVENING IN
SE MISSOURI...ONCE THE WARM ADVECTION DIMINISHES AND FRONTOGENETIC
FORCING TAKES OVER. INTERESTING TO NOTE THAT RUC MODEL THERMAL
PROFILES ARE SOMEWHAT COLDER THAN GFS/NAM PROFILES THIS EVENING.
LATER IN THE EVENING...IN THE 03Z TO 06Z TIME FRAME...RUC
INDICATES THE MAIN FORCING MECHANISM WILL BECOME MID LEVEL
FRONTOGENESIS /850 TO 700 MB LAYER/. THIS WILL RESULT IN LOCALLY
HEAVY PRECIPITATION ACQUIRING MORE OF A BANDED CHARACTER AS IT
OVERSPREADS THE REMAINDER OF THE FORECAST AREA.
LOOKING AT THE 12Z MODEL SUITE...MODELS ARE ALMOST IN LOCKSTEP AS
THE EVENT IS NOW WITHIN THE NEXT 24 HOURS. THE PRIMARY ISSUES ARE
PRECIPITATION TYPE AND LOCATION OF THE DEFORMATION ZONE /HEAVIEST
QPF/.
THE SWATH OF HEAVIEST QPF IS EXPECTED TO OCCUR UNDER THE DEFORMATION
ZONE TO THE NORTHWEST OF THE MID LEVEL LOW. AN INTENSE/COMPACT 500
MB LOW WILL TRACK EAST/NORTHEAST ACROSS TENNESSEE TONIGHT AND
WEDNESDAY. THE ASSOCIATED DEFORMATION ZONE WILL BE ACROSS SE
MISSOURI AND ROUGHLY ALONG AND NORTHWEST OF THE OHIO RIVER. THIS IS
EVIDENT IN THE 12Z GFS...WHICH SHOWS PRONOUNCED MID LEVEL
FRONTOGENETICAL FORCING AND HEAVY QPF COLOCATED WITH EACH OTHER. MOST
OTHER MODEL QPF GUIDANCE INDICATES THE DEFORMATION ZONE LOCATION
IN THE SAME AREA. THEREFORE...EXPECT THE SWATH OF HEAVIEST
SNOWFALL TO OCCUR WITHIN THAT AREA...MAINLY NW OF A KEVV/KPAH LINE.
ONE MAJOR CAVEAT IS PRECIP TYPE. THE MODELS HAVE ACTUALLY WARMED
SOMEWHAT IN THE 800 TO 900 MB LAYER TONIGHT DUE TO PRONOUNCED
EASTERLY FLOW AT 850 MB. ABOVE FREEZING AIR IS FORECAST TO WRAP
WESTWARD AROUND THE TOP OF THE 850 MB LOW...WHICH WILL DELAY THE
CHANGEOVER TO SNOW ALONG AND EAST OF THE KEVV/KPAH CORRIDOR. BASED
ON A BLEND OF SREF/NAM/GFS THERMAL PROFILES...THE CHANGEOVER TO SNOW
FROM KPAH TO KEVV WOULD BE IN THE 07Z TO 11Z TIME FRAME. THIS WOULD
CUT DOWN SIGNIFICANTLY ON FORECAST SNOWFALL AMOUNTS...THOUGH A FEW
HOURS OF HEAVY WET SNOW AND BLIZZARD CONDITIONS ARE STILL EXPECTED.
MODEL BOUNDARY LAYER AND 850 MB TEMPS IN THE FAR SOUTHEAST DO NOT
SUPPORT MUCH SNOW IN THE KHOP AREA...AND THE WINTER STORM WATCH
HAS BEEN DISCONTINUED FOR THAT AREA.
WHERE THE BULK OF THE PRECIPITATION IS ALL SNOW NORTH AND WEST OF
THE KEVV/KPAH CORRIDOR...THERE IS HIGH CONFIDENCE IN A CRIPPLING
BLIZZARD. SNOWFALL AMOUNTS WITHIN THE DEFORMATION ZONE AXIS SHOULD
REACH A FOOT OR SO. LOOKING AT BUFKIT MOMENTUM TRANSFER...BOTH THE
NAM AND GFS INDICATE A HIGH POTENTIAL FOR GUSTS TO AT LEAST 35
KNOTS. THE SREF SHOWS A 50 PERCENT CHANCE OF SUSTAINED WINDS OVER 25
KNOTS IN SE MISSOURI. DESPITE THE HEAVY WET NATURE OF THE
SNOW...DRIFTS WILL BE MEASURED IN FEET IN THE SWATH OF HEAVIEST
SNOW. THE COMBINATION OF HEAVY WET SNOW AND WIND WILL LIKELY CAUSE
SOME POWER OUTAGES.
AS FOR THE TIMING OF THE EVENT...PRECIP WILL SPREAD NORTH ACROSS
THE ENTIRE FORECAST AREA THROUGH 06Z. THE HEAVIEST PRECIP WILL
OCCUR ROUGHLY FROM 03Z TO 12Z. THE DEFORMATION ZONE WILL LIFT OUT
WEDNESDAY MORNING...BUT WINDS WILL NOT BEGIN TO DIMINISH UNTIL AT
LEAST 18Z. THE STRONG WINDS WILL CONTINUE TO RESULT IN EXTENSIVE
BLOWING AND DRIFTING IN THE HEAVY SNOW AREA.
.LONG TERM /THURSDAY THROUGH NEXT TUESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE EXTENDED FORECAST PERIOD...SHORTWAVE RIDGING ALOFT WILL
DOMINATE DURING FROM THURSDAY THROUGH THE EARLY MORNING HOURS ON
FRIDAY. ALTHOUGH THERE WILL BE A LITTLE MORE INSOLATION /SUNSHINE/
AVAILABLE...THERE WILL STILL BE WEAK COLD AIR ADVECTION OVER THE
EXPECTED SNOW FIELD FROM THE TUESDAY NIGHT/WEDNESDAY MORNING WINTER
STORM. WITH THIS IN MIND...LOWERED TEMPERATURES 3 TO 5 DEGREES FROM
LIKELY HIGH TEMPERATURES DUE TO CLOUDS...WINDS AND SNOW COVER. THIS
ADJUSTMENT WAS MAINLY DONE OVER AREAS WHERE TWO OR MORE INCHES WERE
EXPECTED IN THE STORM TOTAL SNOWFALL GRIDDED FORECAST ACROSS THE WFO
PAH FORECAST AREA.
BY FRIDAY AFTERNOON...BOTH 12Z ECMWF AND GFS DETERMINISTIC MODEL
GUIDANCE INDICATE SOME ENHANCEMENT OF THE SHORTWAVE TROUGH MOVING
INTO THE WFO PAH FORECAST AREA IN THE SOUTHWESTERLY FLOW BEHIND THE
AFOREMENTIONED SHORTWAVE RIDGE. THE LIFT ASSOCIATED WITH THIS
FEATURE...COMBINED WITH A RESURGENCE OF CANADIAN POLAR AIR /AS WELL
AS ANY ANTECEDENT SNOW COVER/ SHOULD FORCE THE DEVELOPMENT OF LIGHT
WINTRY MIX LATE FRIDAY NIGHT. WITH THIS IN MIND...ATTEMPTED TO LIMIT
AN MEASURABLE SNOW/SLEET POTENTIAL WHERE THERE WAS NOT A MIX WITH
RAIN. AN INITIAL STAB AT SNOW/SLEET AMOUNTS WOULD LEAD TO AMOUNTS
LESS THAN ONE INCH OVER SOUTHEAST MO...SOUTHERN IL....SOUTHWEST IN
AND WESTERN KY ALONG THE OHIO RIVER. SHOULD THE COLDER AIR FILTER IN
FASTER...MAXIMUM AMOUNTS MAY BE CLOSER TO 1.5 INCHES.
SINCE THIS WEATHER SYSTEM LOOKS FOCUSED WITH MORE ISENTROPIC
LIFT...LEFT THE PRECIPITATION ON THE LIGHTER SIDE IN TERMS OF
INTENSITY AND SHORTER IN OVERALL DURATION OF MEASURABLE
PRECIPITATION.
BEYOND SATURDAY...RIDGING ALOFT WILL BUILD BACK INTO THE AREA WITH
SURFACE HIGH PRESSURE AT THE SURFACE. THIS SCENARIO...WITH ANY
ANTECEDENT SNOW COVER...WILL LEAD TOWARD SLIGHTLY COOLER
TEMPERATURES THAN NORMAL OVER SOUTHERN ILLINOIS AND SOUTHWEST
INDIANA THROUGH NEXT TUESDAY.
THERE IS SOME DIFFERENCE IN TIMING OF THE NEXT SOUTHWEST LOW MOVING
TOWARD THE AREA NEXT TUESDAY/WEDNESDAY...WITH THE ECMWF BEING COOLER
AND FASTER AND THE GFS SLOWER AND WARMER. FOR NOW...WILL KEEP THINGS
DRY THROUGH THE REMAINDER OF THIS FORECAST PACKAGE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 540 PM CST TUE DEC 25 2012
MVFR CIGS WILL DROP TO IFR THROUGH 06Z AND LIFR AFTER 06Z AS
RAIN/WINTRY MIX OF PRECIP SPREADS NORTH ACROSS TAF SITES. PRECIP
WILL BEGIN AS RAIN/SLEET/SNOW CHANGING TO ALL SNOW LATE THIS
EVENING AND OVERNIGHT...WITH IFR/LIFR VSBYS ASSOCIATED WITH PRECIP.
WINDY CONDITIONS EXPECTED WITH NE WINDS AT 10-20 KTS WITH 25-30
KT GUSTS THIS EVENING...BECOMING N AT 15-25 KTS WITH 35 KT GUSTS FROM
AROUND 06Z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR ILZ075>078-080>089-
092-093.
BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR ILZ090-091-094.
MO...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR MOZ076-086-087-100-
107>112-114.
IN...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR INZ081-082-085>088.
KY...WINTER WEATHER ADVISORY FROM 6 AM TO NOON CST WEDNESDAY FOR
KYZ012-017-021-022.
BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR KYZ001>011-013>016-
018>020.
&&
$$
UPDATE...NOLES
SHORT TERM...MY
LONG TERM....SMITH
AVIATION...RST
AREA FORECAST DISCUSSION
NWS PADUCAH KY
540 PM CST TUE DEC 25 2012
.UPDATE...
ISSUED AT 540 PM CST TUE DEC 25 2012
UPDATED AVIATION SECTION FOR 00Z TAF PACKAGE.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE NEAR TERM...AN INTENSIFYING BAND OF MIXED PRECIPITATION IS
LIFTING NORTHWARD FROM NORTHERN ARKANSAS AS OF 20Z. THIS BAND IS
ASSOCIATED WITH STRONG WARM ADVECTION ON EASTERLY FLOW IN THE
850/700 MB LAYER. RUC MODEL BRINGS THE ZONE OF STRONG MID LEVEL
WARM ADVECTION AND ASSOCIATED PRECIP INTO SOUTHEAST MISSOURI BY
00Z. PRECIP TYPE WILL GRADUALLY CHANGE TO SNOW BY MID EVENING IN
SE MISSOURI...ONCE THE WARM ADVECTION DIMINISHES AND FRONTOGENETIC
FORCING TAKES OVER. INTERESTING TO NOTE THAT RUC MODEL THERMAL
PROFILES ARE SOMEWHAT COLDER THAN GFS/NAM PROFILES THIS EVENING.
LATER IN THE EVENING...IN THE 03Z TO 06Z TIME FRAME...RUC
INDICATES THE MAIN FORCING MECHANISM WILL BECOME MID LEVEL
FRONTOGENESIS /850 TO 700 MB LAYER/. THIS WILL RESULT IN LOCALLY
HEAVY PRECIPITATION ACQUIRING MORE OF A BANDED CHARACTER AS IT
OVERSPREADS THE REMAINDER OF THE FORECAST AREA.
LOOKING AT THE 12Z MODEL SUITE...MODELS ARE ALMOST IN LOCKSTEP AS
THE EVENT IS NOW WITHIN THE NEXT 24 HOURS. THE PRIMARY ISSUES ARE
PRECIPITATION TYPE AND LOCATION OF THE DEFORMATION ZONE /HEAVIEST
QPF/.
THE SWATH OF HEAVIEST QPF IS EXPECTED TO OCCUR UNDER THE DEFORMATION
ZONE TO THE NORTHWEST OF THE MID LEVEL LOW. AN INTENSE/COMPACT 500
MB LOW WILL TRACK EAST/NORTHEAST ACROSS TENNESSEE TONIGHT AND
WEDNESDAY. THE ASSOCIATED DEFORMATION ZONE WILL BE ACROSS SE
MISSOURI AND ROUGHLY ALONG AND NORTHWEST OF THE OHIO RIVER. THIS IS
EVIDENT IN THE 12Z GFS...WHICH SHOWS PRONOUNCED MID LEVEL
FRONTOGENETICAL FORCING AND HEAVY QPF COLOCATED WITH EACH OTHER. MOST
OTHER MODEL QPF GUIDANCE INDICATES THE DEFORMATION ZONE LOCATION
IN THE SAME AREA. THEREFORE...EXPECT THE SWATH OF HEAVIEST
SNOWFALL TO OCCUR WITHIN THAT AREA...MAINLY NW OF A KEVV/KPAH LINE.
ONE MAJOR CAVEAT IS PRECIP TYPE. THE MODELS HAVE ACTUALLY WARMED
SOMEWHAT IN THE 800 TO 900 MB LAYER TONIGHT DUE TO PRONOUNCED
EASTERLY FLOW AT 850 MB. ABOVE FREEZING AIR IS FORECAST TO WRAP
WESTWARD AROUND THE TOP OF THE 850 MB LOW...WHICH WILL DELAY THE
CHANGEOVER TO SNOW ALONG AND EAST OF THE KEVV/KPAH CORRIDOR. BASED
ON A BLEND OF SREF/NAM/GFS THERMAL PROFILES...THE CHANGEOVER TO SNOW
FROM KPAH TO KEVV WOULD BE IN THE 07Z TO 11Z TIME FRAME. THIS WOULD
CUT DOWN SIGNIFICANTLY ON FORECAST SNOWFALL AMOUNTS...THOUGH A FEW
HOURS OF HEAVY WET SNOW AND BLIZZARD CONDITIONS ARE STILL EXPECTED.
MODEL BOUNDARY LAYER AND 850 MB TEMPS IN THE FAR SOUTHEAST DO NOT
SUPPORT MUCH SNOW IN THE KHOP AREA...AND THE WINTER STORM WATCH
HAS BEEN DISCONTINUED FOR THAT AREA.
WHERE THE BULK OF THE PRECIPITATION IS ALL SNOW NORTH AND WEST OF
THE KEVV/KPAH CORRIDOR...THERE IS HIGH CONFIDENCE IN A CRIPPLING
BLIZZARD. SNOWFALL AMOUNTS WITHIN THE DEFORMATION ZONE AXIS SHOULD
REACH A FOOT OR SO. LOOKING AT BUFKIT MOMENTUM TRANSFER...BOTH THE
NAM AND GFS INDICATE A HIGH POTENTIAL FOR GUSTS TO AT LEAST 35
KNOTS. THE SREF SHOWS A 50 PERCENT CHANCE OF SUSTAINED WINDS OVER 25
KNOTS IN SE MISSOURI. DESPITE THE HEAVY WET NATURE OF THE
SNOW...DRIFTS WILL BE MEASURED IN FEET IN THE SWATH OF HEAVIEST
SNOW. THE COMBINATION OF HEAVY WET SNOW AND WIND WILL LIKELY CAUSE
SOME POWER OUTAGES.
AS FOR THE TIMING OF THE EVENT...PRECIP WILL SPREAD NORTH ACROSS
THE ENTIRE FORECAST AREA THROUGH 06Z. THE HEAVIEST PRECIP WILL
OCCUR ROUGHLY FROM 03Z TO 12Z. THE DEFORMATION ZONE WILL LIFT OUT
WEDNESDAY MORNING...BUT WINDS WILL NOT BEGIN TO DIMINISH UNTIL AT
LEAST 18Z. THE STRONG WINDS WILL CONTINUE TO RESULT IN EXTENSIVE
BLOWING AND DRIFTING IN THE HEAVY SNOW AREA.
.LONG TERM /THURSDAY THROUGH NEXT TUESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE EXTENDED FORECAST PERIOD...SHORTWAVE RIDGING ALOFT WILL
DOMINATE DURING FROM THURSDAY THROUGH THE EARLY MORNING HOURS ON
FRIDAY. ALTHOUGH THERE WILL BE A LITTLE MORE INSOLATION /SUNSHINE/
AVAILABLE...THERE WILL STILL BE WEAK COLD AIR ADVECTION OVER THE
EXPECTED SNOW FIELD FROM THE TUESDAY NIGHT/WEDNESDAY MORNING WINTER
STORM. WITH THIS IN MIND...LOWERED TEMPERATURES 3 TO 5 DEGREES FROM
LIKELY HIGH TEMPERATURES DUE TO CLOUDS...WINDS AND SNOW COVER. THIS
ADJUSTMENT WAS MAINLY DONE OVER AREAS WHERE TWO OR MORE INCHES WERE
EXPECTED IN THE STORM TOTAL SNOWFALL GRIDDED FORECAST ACROSS THE WFO
PAH FORECAST AREA.
BY FRIDAY AFTERNOON...BOTH 12Z ECMWF AND GFS DETERMINISTIC MODEL
GUIDANCE INDICATE SOME ENHANCEMENT OF THE SHORTWAVE TROUGH MOVING
INTO THE WFO PAH FORECAST AREA IN THE SOUTHWESTERLY FLOW BEHIND THE
AFOREMENTIONED SHORTWAVE RIDGE. THE LIFT ASSOCIATED WITH THIS
FEATURE...COMBINED WITH A RESURGENCE OF CANADIAN POLAR AIR /AS WELL
AS ANY ANTECEDENT SNOW COVER/ SHOULD FORCE THE DEVELOPMENT OF LIGHT
WINTRY MIX LATE FRIDAY NIGHT. WITH THIS IN MIND...ATTEMPTED TO LIMIT
AN MEASURABLE SNOW/SLEET POTENTIAL WHERE THERE WAS NOT A MIX WITH
RAIN. AN INITIAL STAB AT SNOW/SLEET AMOUNTS WOULD LEAD TO AMOUNTS
LESS THAN ONE INCH OVER SOUTHEAST MO...SOUTHERN IL....SOUTHWEST IN
AND WESTERN KY ALONG THE OHIO RIVER. SHOULD THE COLDER AIR FILTER IN
FASTER...MAXIMUM AMOUNTS MAY BE CLOSER TO 1.5 INCHES.
SINCE THIS WEATHER SYSTEM LOOKS FOCUSED WITH MORE ISENTROPIC
LIFT...LEFT THE PRECIPITATION ON THE LIGHTER SIDE IN TERMS OF
INTENSITY AND SHORTER IN OVERALL DURATION OF MEASURABLE
PRECIPITATION.
BEYOND SATURDAY...RIDGING ALOFT WILL BUILD BACK INTO THE AREA WITH
SURFACE HIGH PRESSURE AT THE SURFACE. THIS SCENARIO...WITH ANY
ANTECEDENT SNOW COVER...WILL LEAD TOWARD SLIGHTLY COOLER
TEMPERATURES THAN NORMAL OVER SOUTHERN ILLINOIS AND SOUTHWEST
INDIANA THROUGH NEXT TUESDAY.
THERE IS SOME DIFFERENCE IN TIMING OF THE NEXT SOUTHWEST LOW MOVING
TOWARD THE AREA NEXT TUESDAY/WEDNESDAY...WITH THE ECMWF BEING COOLER
AND FASTER AND THE GFS SLOWER AND WARMER. FOR NOW...WILL KEEP THINGS
DRY THROUGH THE REMAINDER OF THIS FORECAST PACKAGE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 540 PM CST TUE DEC 25 2012
MVFR CIGS WILL DROP TO IFR THROUGH 06Z AND LIFR AFTER 06Z AS
RAIN/WINTRY MIX OF PRECIP SPREADS NORTH ACROSS TAF SITES. PRECIP
WILL BEGIN AS RAIN/SLEET/SNOW CHANGING TO ALL SNOW LATE THIS
EVENING AND OVERNIGHT...WITH IFR/LIFR VSBYS ASSOCIATED WITH PRECIP.
WINDY CONDITIONS EXPECTED WITH NE WINDS AT 10-20 KTS WITH 25-30
KT GUSTS THIS EVENING...BECOMING N AT 15-25 KTS WITH 35 KT GUSTS FROM
AROUND 06Z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR ILZ075>078-080>089-
092-093.
BLIZZARD WARNING FROM MIDNIGHT TONIGHT TO NOON CST WEDNESDAY FOR
ILZ090-091-094.
MO...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR MOZ076-086-087-100-
107>112-114.
IN...BLIZZARD WARNING FROM MIDNIGHT TONIGHT TO NOON CST WEDNESDAY FOR
INZ081-082-085>088.
KY...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR KYZ001.
WINTER WEATHER ADVISORY FROM 6 AM TO NOON CST WEDNESDAY FOR
KYZ012-017-021-022.
BLIZZARD WARNING FROM MIDNIGHT TONIGHT TO NOON CST WEDNESDAY FOR
KYZ002>011-013>016-018>020.
&&
$$
SHORT TERM...MY
LONG TERM....SMITH
AVIATION...RST
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
447 PM EST MON DEC 24 2012
.SYNOPSIS...
LOW PRESSURE AND AN ASSOCIATED FRONTAL BOUNDARY WILL TRACK ACROSS
THE MID ATLANTIC STATES THROUGH TONIGHT. WEAK HIGH PRESSURE WILL
BUILD OVER THE AREA FOR CHRISTMAS DAY. A STRONGER AREA OF LOW
PRESSURE WILL TRACK THROUGH THE TENNESSEE VALLEY CHRISTMAS NIGHT...
THEN CONTINUE ACROSS THE MID ATLANTIC WEDNESDAY INTO WEDNESDAY
EVENING...WITH ITS ASSOCIATED COLD FRONT PUSHING OFF THE COAST BY
EARLY THURSDAY MORNING.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
LATEST MSAS SFC ANALYSIS SHOWS A STATIONARY FRONTAL BOUNDARY DRAPED
ACROSS SOUTHERN VIRGINIA...AND EXTENDING NE TO DEVELOPING LOW
PRESSURE OVER THE OHIO VALLEY. WAA OUT AHEAD OF THE SFC
LOW/MID-LEVEL SHORTWAVE HAS BROUGHT SOME LIGHT RAIN TO THE REGION
TODAY (ESPECIALLY THE NORTHERN/WESTERN FA). AS THE SHORTWAVE DRAWS
CLOSER AND MOVES OVER THE AREA THIS EVENING...AM EXPECTING SPOTTY
LIGHT RAIN TO CONTINUE WITH EMPHASIS ON NORTHERN/WESTERN
LOCATIONS. THIS RAIN MAY NOT HOLD TOGETHER LONG ENOUGH TO REACH
SERN PARTS OF THE FA THROUGH THIS EVENING (DUE TO WEAKENING WAA)...
THEREFORE WILL ONLY CARRY SLIGHT CHC POPS THERE THROUGH 06Z. WILL
HOLD HOLD TO LIKELY/CATEGORICAL POPS (60-90%) FOR NORTHERN
WESTERN/AREAS THROUGH 00Z...THEN TAPER TO CHC POPS (~30%) AFTER
00Z. SHORTWAVE TROUGH AND A WEAK SFC COLD FRONT EXIT THE REGION
AFTER 06Z ALLOWING DRIER ARE TO MOVE INTO THE AREA ALOFT. MODELS
SHOWS ABUNDANT LOW-LEVEL MOISTURE REMAINING IN PLACE OVERNIGHT...
SO LOW OVERCAST (STRATUS) IS EXPECTED TO BE PREVALENT. LOWS TEMPS
TONIGHT WILL NOT BE FAR FROM CURRENT READINGS IN NW PARTS OF THE
FA. LOWS NEAR FREEZING NE TO THE LOW 40S SERN COASTAL AREAS.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
DRY WEATHER IS EXPECTED ON CHRISTMAS DAY WITH THE SKY BECOMING AT
LEAST PARTLY SUNNY...AS WEAK SFC HIGH PRESSURE BUILDS OVER THE
REGION. MAX TEMPS WILL AVERAGE A FEW DEGREES ABOVE NORMAL...
RANGING FROM THE UPR 40S NE TO THE UPR 50S INTERIOR NE NC.
NEXT STRONGER LOW PRESSURE SYSTEM WILL BE DEVELOPING INVOF LOWER MS
VALLEY CHRISTMAS NIGHT...THEN IS FORECAST TO TRACK NE INTO EASTERN
KY BY WED AFTN. AHEAD OF THIS FEATURE...MODELS ARE INDICATED A
NICE WEDGE/CAD SETUP DEVELOPING ACROSS OUR FAR WESTERN/NW COUNTIES
EARLY WED MORNING. OVERRUNNING PRECIP AHEAD OF THE NE ADVANCING
LOW WILL MAKE FOR A TRICKY FORECAST LATE TUES NIGHT/WED MORNING
DUE TO POTENTIAL FOR SOME LIGHT WINTRY PRECIP ACROSS OUR NW
COUNTIES. LATEST BUFKIT DATA SUGGEST POTENTIAL FOR A PERIOD OF
SNOW/SLEET ALONG/NORTH OF A LINE FROM FVX-OFP-XSA LINE. P-TYPE WILL
ALL DEPEND ON EXTENT OF NEAR SFC COLD AIR BY THAT TIME AND JUST
HOW QUICKLY THE CAD ERODES. FOR NOW...HAVE ADDED IN A CHC FOR SOME
SLEET/SNOW ACROSS THE NW COUNTIES WED MORNING BUT WILL NOT SPEAK
OF ANY SNOW/SLEET ACCUMULATIONS ATTM AS IT`S STILL A LOW
CONFIDENCE FORECAST. HOPEFULLY...MODELS WILL HAVE A BETTER HANDLE
ON THIS BY THIS TIME TOMORROW.
OUR ATTENTION THIS TURNS TO A SECONDARY LOW DEVELOPING ESE OF THE
MAIN UPPER LOW THAT WILL TRACK ACROSS CENTRAL VA UP INTO EASTERN
MD LATE WED AFTN INTO WED NIGHT. A WARM FRONT WILL LIFT INTO/THRU
THE FA ON WED AFTN AIDED BY INCREASING SE THEN S WINDS. MAIN AREA
OF MID LEVEL DYNAMICS TO REACH THE FA WED AFTN...AS RIBBON OF
HIGHER SFC DEWPOINTS/LOW LEVEL INSTABILITY WOULD BE SURGING NWD.
THEREFORE...THOUGH IT BEING LATE DECEMBER...CONCERN IS FOR
POSSIBLE CONVECTION AND A PERIOD OF MODERATE/HEAVY RAIN AHEAD
OF/WITH THE COLD FRONT DURING WED AFTN/EVE. QUESTIONS REMAIN WITH
REGARDS TO JUST HOW MUCH TSTM POTENTIAL WILL BE INCREASED LATE WED
DUE TO TRIPLE POINT LOW MOVING NNE THROUGH CENTRAL/EASTERN VA.
THINK GREATEST THREAT FOR STRONG/SEVERE WX WILL REMAIN SOUTH OF
OUR FA IN AREA OF GREATER INSTABILITY...BUT CANNOT RULE OUT AN
ISOLATED STRONG STORM ACROSS OUR SOUTHERN TIER COUNTIES LATE IN
THE DAY. WILL STEADILY INCREASE POPS TUES NIGHT AND BY DAYBREAK
EXPECTED TO HAVE ONGOING PRECIP ACROSS SW AREAS AND SLIGHT CHC
POPS ON THE MD EASTERN SHORE. CATEGORICAL POPS (80-100%) ALL AREAS
ON WED. LOWS TUES NIGHT IN THE LOW 30S NW TO THE MID/UPR 40S SERN
COASTAL AREAS. HIGHS WED NEAR 40 NW TO THE LOW/MID 60S SERN
COASTAL AREAS. BRUNT OF PRECIP WITH THIS SYSTEM WILL COME WED
AFTN/EVENING WHEN HAVE QPF AMOUNTS BETWEEN 0.75"-1.5" WITH LOCALLY
HIGHER AMOUNTS POSSIBLE.
SFC LOW MOVES OFFSHORE WED NIGHT WITH TRAILING UPPER LOW MOVING
ACROSS NORTHERN VA. WILL LINGER POPS ACROSS MOST AREAS THROUGH 06Z
THURS...WITH CHANCE POPS ACROSS JUST THE NORTHERN TIER COUNTIES
AFTER 06Z. LOWS IN THE MID 30S TO MID 40S. CHILLY W/NW WINDS
DEVELOP ON THURSDAY AS THE UPPER LOW DEPARTS AND DRIER AREA
RETURNS. HIGHS THURSDAY IN THE MID 40S NW TO THE LOW 50S SE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MODELS IN RELATIVELY GOOD AGREEMENT WITH A HIGH AMPLITUDE PATTERN
ACROSS THE U.S. UPPER LEVEL ENERGY DIGS INTO THE SW US AND MOVES
NORTHEAST ACROSS THE MID ATLANTIC. THE MAIN PROBLEM FOR THE
EXTENDED IS THE DEVELOPMENT OF LOW PRESSURE FOR SATURDAY INTO
SUNDAY. HPC WAS FOLLOWING A BLEND OF THE GFS AND ECMWF FOR THIS
DEVELOPING LOW. LOOKING AT THE 12Z GFS AND ECMWF THEY NOW BECOME
CLOSER IN AGREEMENT FOR OUR AREA WITH LOW PRESSURE DEVELOPING IN
THE SOUTHEASTERN US AND MOVING OFF THE MID ATLANTIC COAST SATURDAY
INTO SUNDAY. THERE ARE STILL QUESTIONS ABOUT THE TIMING AND
LOCATION OF THIS LOW. SO WENT VERY GENERIC WITH THE PRECIPITATION
TYPE FOR THIS STORM. THE MODELS ALL AGREE ENOUGH COLD AIR IN PLACE
TO START THE NORTHWEST SECTIONS OF THE AREA WITH EITHER SNOW OR A
MIX OF RAIN AND SNOW. MOST OF THE AREA LEANED TOWARD JUST RAIN FOR
NOW. WILL HAVE TO WATCH THIS SYSTEM AS IT DEVELOPS TOWARD THE
WEEKEND. TEMPERATURE FORECAST WENT CLOSE TO BOTH GRIDDED MOS AND
HPC WHICH WERE SIMILAR. OTHER THEN THE WEEKEND STORM MAINLY A DRY
FORECAST WITH TEMPERATURES NEAR TO A LITTLE BELOW NORMAL.
&&
.AVIATION /22Z MONDAY THROUGH SATURDAY/...
CONTINUING TO HAVE LIGHT RAIN MOVING NORTHEAST AHEAD OF A PV MAX
IN THE OHIO VALLEY. THIS PRECIPITATION WILL MOVE OFF THE COAST
AROUND 00Z TONIGHT. HOWEVER THE COLD FRONT ACCOMPANYING THE
PRECIPITATION IS QUITE WEAK AND STILL CONTAINS PLENTY OF LOW LEVEL
MOISTURE. THIS WILL CAUSE CEILINGS TO LOWER AFTER THE RAIN ENDS
AND EXPECT IFR STRATUS OVERNIGHT AT ALL THE TAF SITES. THIS IS ON
THE LOW END OF MOST STATISTICAL GUIDANCE BUT THE RAP NAM AND GFS
BUFKIT SOUNDINGS DO SUPPORT THE LOWER CLOUD DECK. PLENTY OF DRYING
ALOFT TONIGHT. THIS WILL HELP IN THE MORNING AS WINDS SHOULD
INCREASE ENOUGH AND WITH THE SUNSHINE THE LOW CLOUDS WILL BREAK UP
DURING THE MORNING WITH VFR FOR THE REMAINDER OF THE DAY.
NEXT WEATHER SYSTEM WILL BE LOW PRESSURE MOVING THROUGH WEDNESDAY
INTO THURSDAY. THIS WILL LIKELY BRING SOME IFR CONDITIONS FOR A
TIME WEDNESDAY AND WEDNESDAY NIGHT AS RAIN MOVES ACROSS THE AREA.
COULD SEE ISOLATED THUNDERSTORMS OVER SOUTHEAST VIRGINIA WEDNESDAY
AFTERNOON OR EVENING. VFR CONDITIONS RETURN DURING THURSDAY WITH
NEXT CHANCE OF LOWER CIGS AND VSBY OVER THE WEEKEND BUT STILL
PLENTY OF UNCERTAINTY ON THIS.
&&
.MARINE...
NOT MANY CHANGES NECESSARY TO ONGOING MARINE FORECAST AS OF THIS
AFTN.
LOW PRESSURE CONTINUES TO TRACK NE FROM THE OH VALLEY INTO WRN PA
THIS EVENING AND WILL PUSH OFF THE NJ COAST BY CHRISTMAS MORNING.
WEAK ONSHORE FLOW EARLY THIS EVENING WILL BECOME WESTERLY BY LATE
THIS EVENING. A BACKDOOR FRONT THEN DEVELOPS TUE AFTN INTO TUE NIGHT
PRIOR TO A WARM FRONT LIFTING NWD ON WED. THIS BACKDOOR FRONT WILL
REINFORCE A NNW-N WIND DIRECTION OVER THE WATERS DURING THIS
TIME...HOWEVER CAA WILL BE RATHER WEAK AND WIND SPEEDS SHOULD STAY
GENERALLY AOB 15 KT ALL WATERS UNTIL LATE TUE NIGHT/EARLY WED
MORNING WHEN WINDS MAY FLIRT WITH LOW-END SCA FOR BAY/RIVERS/SOUND
(15-20 KT). CONFIDENCE NOT HIGH ENOUGH YET TO HOIST FLAGS ATTM.
EXPECT BAY WAVES AVERAGING 1-2 FT AND SEAS 2-4 FT TONIGHT THROUGH
TUE EVENING.
THE WARM FRONT WILL RAPIDLY WEAKEN THE BACKDOOR FRONT ON WED AS A
STRONG AND POTENT LOW PRESSURE SYSTEM LIFTS ENE INTO THE AREA FROM
THE TN VALLEY. AS STRONG HIGH PRESSURE REMAINS IN PLACE NORTH OF THE
GREAT LAKES IN CANADA...A STRONG PRESSURE GRADIENT WILL FORM BTWN
THE TWO SYSTEMS AND ESSENTIALLY OVER THE MID ATLANTIC REGION. SINCE
FORECAST MODELS TYPICALLY UNDERCUT NE WIND SPEEDS OVER THE MARINE
AREA...HAVE MADE LITTLE TO NO CHANGE TO ONGOING FORECAST. THE MAIN
FORECAST CHALLENGE IS TO DETERMINE HOW RAPIDLY THE LOW INTENSIFIES
AND SUBSEQUENTLY THE WINDS AS THE LOW MOVES TWD THE COAST BY WED
NIGHT. STILL EXPECTING A STRONG SCA EVENT ON WED...WITH POSSIBLE
GALES A FEW HOURS EITHER SIDE OF THE FRONTAL PASSAGE (ESPECIALLY
ALONG THE COAST N OF CAPE CHARLES). SEAS LIKELY BUILD TO 7-10 FT
OVER PORTIONS OF THE COASTAL WATERS AND 4-6 FT IN THE BAY. GALES
WILL CONTINUE TO BE POSSIBLE ON THU AS WINDS SHIFT TO THE W AND THE
LOW SLIDES OFFSHORE. CAA WILL BE RATHER WEAK ON THU AND IS NOT
EXPECTED TO BE THE DRIVING INFLUENCE ON WIND SPEEDS. CONDITIONS
WILL SLOWLY SUBSIDE THROUGH THU NIGHT AS THE LOW MOVES INTO THE
CANADIAN MARITIMES...WITH SEAS SLOWER TO FOLLOW INTO FRI.
&&
.TIDES/COASTAL FLOODING...
TIDAL FLOODING IS POSSIBLE DURING THE WED AFTN THROUGH THU AFTN
HIGH TIDE CYCLES (DEPENDING ON EXACT LOCATION). MDL AND CBOFS
FORECASTS CONTINUE TO SHOW TIDAL ANOMALIES OF 0.5-1.5 FT ABOVE
NORMAL AT VARIOUS LOCATIONS THROUGHOUT THE MD/VA LOWER EASTERN
SHORE DURING THIS TIMEFRAME. AT OCEAN CITY...TIDAL ANOMALIES ARE
FLIRTING WITH MINOR FLOODING THRESHOLDS NOW. CONSIDERING THAT THE
CURRENT DATA MAY BE UNDERDONE...WILL NEED TO CONTINUE TO MONITOR
AS THE FULL MOON PHASE APPROACHES EARLY FRI MORNING.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDM
NEAR TERM...JDM
SHORT TERM...JDM
LONG TERM...JAB
AVIATION...LKB/JAB
MARINE...BMD
TIDES/COASTAL FLOODING...AKQ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
359 PM EST MON DEC 24 2012
.SYNOPSIS...
LOW PRESSURE AND AN ASSOCIATED FRONTAL BOUNDARY WILL TRACK ACROSS
THE MID ATLANTIC STATES THROUGH TONIGHT. WEAK HIGH PRESSURE WILL BUILD
OVER THE AREA FOR CHRISTMAS DAY. A STRONGER AREA OF LOW PRESSURE
WILL TRACK THROUGH THE TENNESSEE VALLEY CHRISTMAS NIGHT...THEN
CONTINUE ACROSS THE MID ATLANTIC WEDNESDAY INTO WEDNESDAY
EVENING...WITH ITS ASSOCIATED COLD FRONT PUSHING OFF THE COAST BY
EARLY THURSDAY MORNING.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST MSAS SFC ANALYSIS SHOWS A STATIONARY FRONTAL BOUNDARY DRAPED
ACROSS SOUTHERN VIRGINIA...AND EXTENDING NE TO DEVELOPING LOW
PRESSURE OVER THE OHIO VALLEY. WAA OUT AHEAD OF THE SFC LOW/MID-
LEVEL SHORTWAVE HAS BROUGHT SOME LIGHT RAIN TO THE REGION TODAY
(ESPECIALLY THE NORTHERN/WESTERN FA). AS THE SHORTWAVE DRAWS
CLOSER AND MOVES OVER THE AREA THIS EVENING...AM EXPECTING SPOTTY
LIGHT RAIN TO CONTINUE WITH EMPHASIS ON NORTHERN/WESTERN
LOCATIONS. THIS RAIN MAY NOT HOLD TOGETHER LONG ENOUGH TO REACH
SERN PARTS OF THE FA THROUGH THIS EVENING (DUE TO WEAKENING WAA)...
THEREFORE WILL ONLY CARRY SLIGHT CHC POPS THERE THROUGH 06Z. WILL
HOLD HOLD TO LIKELY/CATEGORICAL POPS (60-90%) FOR NORTHERN
WESTERN/AREAS THROUGH 00Z...THEN TAPER TO CHC POPS (~30%) AFTER
00Z. SHORTWAVE TROUGH AND A WEAK SFC COLD FRONT EXIT THE REGION
AFTER 06Z ALLOWING DRIER ARE TO MOVE INTO THE AREA ALOFT. MODELS
SHOWS ABUNDANT LOW-LEVEL MOISTURE REMAINING IN PLACE
OVERNIGHT...SO LOW OVERCAST (STRATUS) IS EXPECTED TO BE PREVALENT.
LOWS TEMPS TONIGHT WILL NOT BE FAR FROM CURRENT READINGS IN NW
PARTS OF THE FA. LOWS NEAR FREEZING NE TO THE LOW 40S SERN COASTAL
AREAS.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
DRY WEATHER IS EXPECTED ON CHRISTMAS DAY WITH THE SKY BECOMING AT
LEAST PARTLY SUNNY...AS WEAK SFC HIGH PRESSURE BUILDS OVER THE REGION.
MAX TEMPS WILL AVERAGE A FEW DEGREES ABOVE NORMAL...RANGING FROM THE
UPR 40S NE TO THE UPR 50S INTERIOR NE NC.
NEXT STRONGER LOW PRESSURE SYSTEM WILL BE DEVELOPING INVOF LOWER MS
VALLEY CHRISTMAS NIGHT...THEN IS FORECAST TO TRACK NE INTO EASTERN
KY BY WED AFTN. AHEAD OF THIS FEATURE...MODELS ARE INDICATED A
NICE WEDGE/CAD SETUP DEVELOPING ACROSS OUR FAR WESTERN/NW COUNTIES
EARLY WED MORNING. OVERRUNNING PRECIP AHEAD OF THE NE ADVANCING
LOW WILL MAKE FOR A TRICKY FORECAST LATE TUES NIGHT/WED MORNING
DUE TO POTENTIAL FOR SOME LIGHT WINTRY PRECIP ACROSS OUR NW
COUNTIES. LATEST BUFKIT DATA SUGGEST POTENTIAL FOR A PERIOD OF
SNOW/SLEET ALONG/NORTH OF A LINE FROM FVX-OFP-XSA LINE. P-TYPE WILL
ALL DEPEND ON EXTENT OF NEAR SFC COLD AIR BY THAT TIME AND JUST
HOW QUICKLY THE CAD ERODES. FOR NOW...HAVE ADDED IN A CHC FOR SOME
SLEET/SNOW ACROSS THE NW COUNTIES WED MORNING BUT WILL NOT SPEAK
OF ANY SNOW/SLEET ACCUMULATIONS ATTM AS IT`S STILL A LOW
CONFIDENCE FORECAST. HOPEFULLY...MODELS WILL HAVE A BETTER HANDLE ON
THIS BY THIS TIME TOMORROW.
OUR ATTENTION THIS TURNS TO A SECONDARY LOW DEVELOPING ESE OF THE MAIN
UPPER LOW THAT WILL TRACK ACROSS CENTRAL VA UP INTO EASTERN MD LATE
WED AFTN INTO WED NIGHT. A WARM FRONT WILL LIFT INTO/THRU THE FA ON
WED AFTN AIDED BY INCREASING SE THEN S WINDS. MAIN AREA OF MID LEVEL
DYNAMICS TO REACH THE FA WED AFTN...AS RIBBON OF HIGHER SFC
DEWPOINTS/LOW LEVEL INSTABILITY WOULD BE SURGING NWD. THEREFORE...THOUGH
IT BEING LATE DECEMBER...CONCERN IS FOR POSSIBLE CONVECTION AND A
PERIOD OF MODERATE/HEAVY RAIN AHEAD OF/WITH THE COLD FRONT DURING WED
AFTN/EVE. QUESTIONS REMAIN WITH REGARDS TO JUST HOW MUCH TSTM
POTENTIAL WILL BE INCREASED LATE WED DUE TO TRIPLE POINT LOW
MOVING NNE THROUGH CENTRAL/EASTERN VA. THINK GREATEST THREAT FOR
STRONG/SEVERE WX WILL REMAIN SOUTH OF OUR FA IN AREA OF GREATER
INSTABILITY...BUT CANNOT RULE OUT AN ISOLATED STRONG STORM ACROSS
OUR SOUTHERN TIER COUNTIES LATE IN THE DAY. WILL STEADILY INCREASE
POPS TUES NIGHT AND BY DAYBREAK EXPECTED TO HAVE ONGOING PRECIP
ACROSS SW AREAS AND SLIGHT CHC POPS ON THE MD EASTERN SHORE.
CATEGORICAL POPS (80-100%) ALL AREAS ON WED. LOWS TUES NIGHT IN
THE LOW 30S NW TO THE MID/UPR 40S SERN COASTAL AREAS. HIGHS WED
NEAR 40 NW TO THE LOW/MID 60S SERN COASTAL AREAS. BRUNT OF PRECIP
WITH THIS SYSTEM WILL COME WED AFTN/EVENING WHEN HAVE QPF AMOUNTS
BETWEEN 0.75"-1.5" WITH LOCALLY HIGHER AMOUNTS POSSIBLE.
SFC LOW MOVES OFFSHORE WED NIGHT WITH TRAILING UPPER LOW MOVING
ACROSS NORTHERN VA. WILL LINGER POPS ACROSS MOST AREAS THROUGH 06Z
THURS...WITH CHANCE POPS ACROSS JUST THE NORTHERN TIER COUNTIES
AFTER 06Z. LOWS IN THE MID 30S TO MID 40S. CHILLY W/NW WINDS
DEVELOP ON THURSDAY AS THE UPPER LOW DEPARTS AND DRIER AREA
RETURNS. HIGHS THURSDAY IN THE MID 40S NW TO THE LOW 50S SE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MODELS IN RELATIVELY GOOD AGREEMENT WITH A HIGH AMPLITUDE PATTERN
ACROSS THE U.S. UPPER LEVEL ENERGY DIGS INTO THE SW US AND MOVES
NORTHEAST ACROSS THE MID ATLANTIC. THE MAIN PROBLEM FOR THE EXTENDED
IS THE DEVELOPMENT OF LOW PRESSURE FOR SATURDAY INTO SUNDAY. HPC WAS
FOLLOWING A BLEND OF THE GFS AND ECMWF FOR THIS DEVELOPING LOW.
LOOKING AT THE 12Z GFS AND ECMWF THEY NOW BECOME CLOSER IN AGREEMENT
FOR OUR AREA WITH LOW PRESSURE DEVELOPING IN THE SOUTHEASTERN US AND
MOVING OFF THE MID ATLANTIC COAST SATURDAY INTO SUNDAY. THERE ARE
STILL QUESTIONS ABOUT THE TIMING AND LOCATION OF THIS LOW. SO WENT
VERY GENERIC WITH THE PRECIPITATION TYPE FOR THIS STORM. THE MODELS
ALL AGREE ENOUGH COLD AIR IN PLACE TO START THE NORTHWEST SECTIONS
OF THE AREA WITH EITHER SNOW OR A MIX OF RAIN AND SNOW. MOST OF THE
AREA LEANED TOWARD JUST RAIN FOR NOW. WILL HAVE TO WATCH THIS SYSTEM
AS IT DEVELOPS TOWARD THE WEEKEND. TEMPERATURE FORECAST WENT CLOSE
TO BOTH GRIDDED MOS AND HPC WHICH WERE SIMILAR. OTHER THEN THE
WEEKEND STORM MAINLY A DRY FORECAST WITH TEMPERATURES NEAR TO A
LITTLE BELOW NORMAL.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
CONTINUING TO HAVE LIGHT RAIN MOVING NORTHEAST AHEAD OF A PV MAX
IN THE OHIO VALLEY. THIS PRECIPITATION WILL MOVE OFF THE COAST
AROUND 00Z TONIGHT. HOWEVER THE COLD FRONT ACCOMPANYING THE
PRECIPITATION IS QUITE WEAK AND STILL CONTAINS PLENTY OF LOW LEVEL
MOISTURE. THIS WILL CAUSE CEILINGS TO LOWER AFTER THE RAIN ENDS
AND EXPECT IFR STRATUS OVERNIGHT AT ALL THE TAF SITES. THIS IS ON
THE LOW END OF MOST STATISTICAL GUIDANCE BUT THE RAP NAM AND GFS
BUFKIT SOUNDINGS DO SUPPORT THE LOWER CLOUD DECK. PLENTY OF DRYING
ALOFT TONIGHT. THIS WILL HELP IN THE MORNING AS WINDS SHOULD
INCREASE ENOUGH AND WITH THE SUNSHINE THE LOW CLOUDS WILL BREAK UP
DURING THE MORNING WITH VFR FOR THE REMAINDER OF THE DAY.
NEXT WEATHER SYSTEM WILL BE LOW PRESSURE MOVING THROUGH WEDNESDAY
INTO THURSDAY. THIS WILL LIKELY BRING SOME IFR CONDITIONS FOR A
TIME WEDNESDAY AND WEDNESDAY NIGHT AS RAIN MOVES ACROSS THE AREA.
COULD SEE ISOLATED THUNDERSTORMS OVER SOUTHEAST VIRGINIA WEDNESDAY
AFTERNOON OR EVENING. VFR CONDITIONS RETURN DURING THURSDAY WITH
NEXT CHANCE OF LOWER CIGS AND VSBY OVER THE WEEKEND BUT STILL
PLENTY OF UNCERTAINTY ON THIS.
&&
.MARINE...
WEAK COLD FRONT NOW DROPPING THROUGH NORTHERN PORTIONS OF THE MARINE
AREA...SHIFTING WINDS TO THE N. THUS FAR WIND SPEEDS HAVE BEEN 10 KT
OR LESS...AND EVEN W/ SOME INCREASE EXPECTED...SCA CONDITIONS ARE
NOT ANTICIPATED. BOUNDARY STALLS/DISSIPATES OVER SE VA/NE NC LATER
TODAY AS LOW PRESSURE TRACKS NE FROM THE OHIO VALLEY TO PA BY THIS
EVENING...AND OFF THE NJ COAST CHRISTMAS MORNING. WINDS WILL SHIFT
BACK TO THE SE AND THEN THE SW LATER TONIGHT AND ONCE AGAIN TURN
NORTHERLY DURING THE DAY CHRISTMAS. WIND SPEEDS NOT EXPECTED TO
REACH SCA THRESHOLDS DUE TO THE LACK OF COLD AIR MAKING IT SOUTH
INTO THE REGION (ALTHOUGH A FEW HRS WORTH OF WINDS GUSTING CLOSE TO
20 KT WILL BE POSSIBLE W/ THE FRONT EARLY TUE. BAY WAVES AVG 1-2 FT
AND SEAS 2-4 FT THROUGH TUE EVENING.
ON WED...A MUCH MORE POTENT SYSTEM WILL LIFT ENE FROM THE TENNESSEE
VALLEY...AS STRONG HIGH PRESSURE REMAINS IN PLACE NORTH OF THE GREAT
LAKES IN CANADA. THIS PATTERN YIELDS A STRONG PRESSURE GRADIENT AND
TYPICALLY MODELS ARE UNDERDONE OVER THE MARINE AREA W/ NE
WINDS...PARTICULARLY W/ RAPID INTENSIFICATION OF THE SFC LOW AS IT
MOVES TOWARDS THE COAST BY WED NIGHT. EXPECT AT LEAST A STRONG SCA
EVENT ON WED...WITH GALES A GOOD POSSIBILITY ALONG THE COAST
(ESPECIALLY N OF CAPE CHARLES). SEAS LIKELY BUILD TO 8-10 FT OVER
PORTIONS OF THE COASTAL WATERS AND 3-5 FT IN THE BAY. GALES WILL
CONTINUE TO BE POSSIBLE ON THU AS WINDS SHIFT TO THE W AS THE LOW
SLIDES OFFSHORE. COLD AIR ADVECTION IS NOT ALL THAT STRONG THOUGH SO
IT MAY NOT BE REAL LONG-LIVED.
TIDAL FLOODING IS ALSO POSSIBLE BY WED/WED NIGHT...MDL AND CBOFS
GUIDANCE IS SHOWING ANOMALIES UP TO 1.5 FT AT OCEAN CITY (AND 1 FT
OR LESS ELSEWHERE). ALTHOUGH THIS WOULD NOT YIELD EVEN MINOR
FLOODING...IT IS PROBABLY A BIT UNDERDONE AS THE GUIDANCE TENDS TO
BE BEYOND 36 HRS. WILL CONTINUE TO MONITOR.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TMG/JDM
NEAR TERM...JDM
SHORT TERM...JDM
LONG TERM...JAB
AVIATION...LKB/JAB
MARINE...
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
118 PM EST MON DEC 24 2012
.SYNOPSIS...
LOW PRESSURE AND AN ASSOCIATED FRONTAL BOUNDARY WILL TRACK ACROSS
THE MID ATLANTIC STATES TODAY INTO TONIGHT. WEAK HIGH PRESSURE
WILL BUILD OVER THE AREA FOR CHRISTMAS DAY. A STRONGER AREA OF
LOW PRESSURE WILL TRACK THROUGH THE TENNESSEE VALLEY CHRISTMAS
NIGHT...THEN CONTINUE ACROSS THE MID ATLANTIC WEDNESDAY INTO
WEDNESDAY EVENING...WITH ITS ASSOCIATED COLD FRONT PUSHING OFF
THE COAST BY EARLY THURSDAY MORNING.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WEAK LO PRES CURRENTLY MOVING INTO THE LWR OH VLY AND TN VLY WILL
TRACK ENE TODAY INTO TNGT PUSHING A WARM FRONT THEN A COLD FRONT
ACRS THE REGION. ASSOCIATED MOISTURE AXIS TO SWING (W-E) ACRS THE
FA TODAY INTO THIS EVENG...WITH HIGHEST POPS (70-100%) OVR THE NRN
AND WRN PORTIONS OF THE AREA...DECREASING TO 20-30% EXTRM SE
VA/CSTL NE NC. QUITE A DISCERNIBLE TEMP GRADIENT ACROSS THE FA
TODAY...WITH HI TEMPS FM NR 40 FAR NW...TO THE MID 50S EXTRM SE
VA AND NE NC.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
ALTHO PCPN WILL END BY VRY EARLY TUE MORNG...EXPECT SKY TO REMAIN
GENERALLY MSTLY CLDY IF NOT CLDY TNGT ACRS THE REGION...DUE TO
LIGHT WINDS AND NO REAL DRIER AIR FILTERING IN AT THE LO LVLS.
LOWS TNGT RANGING FM THE LWR 30S TO LWR 40S. DRY WX ON TUE WITH
THE SKY BECMG AT LEAST PRTLY SNY...AS WEAK HI PRES BLDS OVR THE
AREA. MAX TEMPS WILL AVERAGE A FEW DEGREES ABV NORMAL...RANGING FM
THE UPR 40S TO THE UPR 50S.
NEXT STRONGER LO PRES SYSTEM WILL BE DEVELOPING INVOF W/CNTRL
GULF STATES LATE TUE INTO TUE NGT...THEN IS FCST TO TRACK TO THE NE
INTO ERN KY BY WED AFTN. A SECONDARY LO ESE OF THE UPR LO WILL
THEN TRACK ACRS CNTRL VA UP INTO ERN MD LATE WED AFTN INTO WED
NGT. A WARM FRNT WILL LIFT INTO/THRU THE FA ON WED AIDED BY
INCREASING SE THEN S WINDS. MAIN AREA OF MID LVL DYNAMICS TO
REACH THE FA WED AFTN...AS RIBBON OF HIGHER SFC DEWPTS/LO LVL
INSTABILITY WOULD BE SURGING NWD. THEREFORE...THOUGH IT BEING LATE
DEC...CONCERN IS FOR POSSIBLE CONVECTION AND A PERIOD OF MDT/HVY
RAIN AHEAD OF/WITH THE COLD FRONT DURG WED AFTN. WILL (STRNG) TSTM
POTENTIAL BE INCREASED BY TRIPLE POINT LO MOVING NNE OVR THE
PIEDMONT? WILL HAVE 80% POPS...AND MAINTAIN CHC T FOR SRN HALF OF
VA/NE NC (WED AFTN). HI TEMPS WED FM THE UPR 40S/LWR 50S NW TO
THE MID TO UPR 60S IN EXTRM SE VA/CSTL NE NC.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
DECENT MODEL AGREEMENT WED NIGHT WITH A QUICK COLD FRONTAL PASSAGE
AS DEEPENING LOW PRESSURE QUICKLY MOVES NORTHEAST OF THE REGION.
KEPT CHC EVE POPS AHEAD OF FROPA. CAA KICKS IN ALLOWING DRY SLOT TO
PUNCH NE AND CUT PCPN OFF AFTR MIDNITE. LOWS IN THE 30S.
THURSDAY APPEARS TO BE ANOTHER DAY LIKE SATURDAY WAS. STRNG PRS
GRDNT ARND DEPARTING LOW RESULTS IN A BREEZY/WINDY DAY WITH PTNTL
FOR GUSTS OVER 30 MPH INLAND AND GALE FORCE WINDS OVER THE WATERS.
PT SUNNY AS COLD AIR ALOFT RESULTS IN SC DVLPMNT DRNG THE DAY. KEPT
IT DRY WITH HIGHS IN THE 40S TO L50S SERN CNTYS.
HIGH PRS BUILDS INTO THE AREA THURS NITE & FRI. THIS KEEPS IT DRY
WITH DMNSHG WINDS. LOWS THURS NITE M20S-L30S. HIGHS FRI IN THE 40S.
MODELS THEN DIVERGE BY NEXT WEEKEND AS YET ANTHR (WEAKER) SYSTM
EJECTS OUT OF SW THEN MOVES ACROSS THE SRN CONUS. ECMWF QUICKER IN
BRINGING PCPN IN FRI NITE WITH THE GFS GIVING THE REGION THE OLD
SPLIT IN PCPN BATCHES SAT. WILL KEEP LOW CHC (LIQUID) POPS IN FOR
SAT. SOME P-TYPE ISSUES ARE PSBL IF PCPN COMES IN A BIT FASTER FRI
NITE. LOWS FRI NITE U20S-M30S. HIGHS SAT IN THE 40S AND 50S. COLDER
BEHIND SYSTM SUNDAY. LOWS SAT NITE M20S-M30S. HIGHS SUN IN THE
40S.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
CONTINUING TO HAVE LIGHT RAIN MOVING NORTHEAST AHEAD OF A PV MAX
IN THE OHIO VALLEY. THIS PRECIPITATION WILL MOVE OFF THE COAST
AROUND 00Z TONIGHT. HOWEVER THE COLD FRONT ACCOMPANYING THE
PRECIPITATION IS QUITE WEAK AND STILL CONTAINS PLENTY OF LOW LEVEL
MOISTURE. THIS WILL CAUSE CEILINGS TO LOWER AFTER THE RAIN ENDS
AND EXPECT IFR STRATUS OVERNIGHT AT ALL THE TAF SITES. THIS IS ON
THE LOW END OF MOST STATISTICAL GUIDANCE BUT THE RAP NAM AND GFS
BUFKIT SOUNDINGS DO SUPPORT THE LOWER CLOUD DECK. PLENTY OF DRYING
ALOFT TONIGHT. THIS WILL HELP IN THE MORNING AS WINDS SHOULD
INCREASE ENOUGH AND WITH THE SUNSHINE THE LOW CLOUDS WILL BREAK UP
DURING THE MORNING WITH VFR FOR THE REMAINDER OF THE DAY.
NEXT WEATHER SYSTEM WILL BE LOW PRESSURE MOVING THROUGH WEDNESDAY
INTO THURSDAY. THIS WILL LIKELY BRING SOME IFR CONDITIONS FOR A
TIME WEDNESDAY AND WEDNESDAY NIGHT AS RAIN MOVES ACROSS THE AREA.
COULD SEE ISOLATED THUNDERSTORMS OVER SOUTHEAST VIRGINIA WEDNESDAY
AFTERNOON OR EVENING. VFR CONDITIONS RETURN DURING THURSDAY WITH
NEXT CHANCE OF LOWER CIGS AND VSBY OVER THE WEEKEND BUT STILL
PLENTY OF UNCERTAINTY ON THIS.
&&
.MARINE...
WEAK COLD FRONT NOW DROPPING THROUGH NORTHERN PORTIONS OF THE MARINE
AREA...SHIFTING WINDS TO THE N. THUS FAR WIND SPEEDS HAVE BEEN 10 KT
OR LESS...AND EVEN W/ SOME INCREASE EXPECTED...SCA CONDITIONS ARE
NOT ANTICIPATED. BOUNDARY STALLS/DISSIPATES OVER SE VA/NE NC LATER
TODAY AS LOW PRESSURE TRACKS NE FROM THE OHIO VALLEY TO PA BY THIS
EVENING...AND OFF THE NJ COAST CHRISTMAS MORNING. WINDS WILL SHIFT
BACK TO THE SE AND THEN THE SW LATER TONIGHT AND ONCE AGAIN TURN
NORTHERLY DURING THE DAY CHRISTMAS. WIND SPEEDS NOT EXPECTED TO
REACH SCA THRESHOLDS DUE TO THE LACK OF COLD AIR MAKING IT SOUTH
INTO THE REGION (ALTHOUGH A FEW HRS WORTH OF WINDS GUSTING CLOSE TO
20 KT WILL BE POSSIBLE W/ THE FRONT EARLY TUE. BAY WAVES AVG 1-2 FT
AND SEAS 2-4 FT THROUGH TUE EVENING.
ON WED...A MUCH MORE POTENT SYSTEM WILL LIFT ENE FROM THE TENNESSEE
VALLEY...AS STRONG HIGH PRESSURE REMAINS IN PLACE NORTH OF THE GREAT
LAKES IN CANADA. THIS PATTERN YIELDS A STRONG PRESSURE GRADIENT AND
TYPICALLY MODELS ARE UNDERDONE OVER THE MARINE AREA W/ NE
WINDS...PARTICULARLY W/ RAPID INTENSIFICATION OF THE SFC LOW AS IT
MOVES TOWARDS THE COAST BY WED NIGHT. EXPECT AT LEAST A STRONG SCA
EVENT ON WED...WITH GALES A GOOD POSSIBILITY ALONG THE COAST
(ESPECIALLY N OF CAPE CHARLES). SEAS LIKELY BUILD TO 8-10 FT OVER
PORTIONS OF THE COASTAL WATERS AND 3-5 FT IN THE BAY. GALES WILL
CONTINUE TO BE POSSIBLE ON THU AS WINDS SHIFT TO THE W AS THE LOW
SLIDES OFFSHORE. COLD AIR ADVECTION IS NOT ALL THAT STRONG THOUGH SO
IT MAY NOT BE REAL LONG-LIVED.
TIDAL FLOODING IS ALSO POSSIBLE BY WED/WED NIGHT...MDL AND CBOFS
GUIDANCE IS SHOWING ANOMALIES UP TO 1.5 FT AT OCEAN CITY (AND 1 FT
OR LESS ELSEWHERE). ALTHOUGH THIS WOULD NOT YIELD EVEN MINOR
FLOODING...IT IS PROBABLY A BIT UNDERDONE AS THE GUIDANCE TENDS TO
BE BEYOND 36 HRS. WILL CONTINUE TO MONITOR.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TMG
NEAR TERM...JDM/TMG
SHORT TERM...ALB/TMG
LONG TERM...MPR
AVIATION...LKB/JAB
MARINE...LKB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
619 AM EST MON DEC 24 2012
.SYNOPSIS...
A WEAK SURFACE LOW WILL PUSH ACROSS THE AREA TODAY...BRINGING A
LIGHT WINTRY MIX OF PRECIPITATION ACROSS THE RIDGES AND NORTH OF
PITTSBURGH WITH MOSTLY RAIN ELSEWHERE. WEAK HIGH PRESSURE WILL PASS
NORTHWEST OF THE AREA AND ALLOW FOR A MOSTLY DRY CHRISTMAS DAY. THE
NEXT LOW WILL THE BRING A WINTRY MIX ACROSS THE AREA WEDNESDAY INTO
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A PAIR OF SHORT WAVES
UPSTREAM ALONG THE SAME AXIS OF A BROAD UPPER TROUGH. THE NORTHERN
WAVE IS THE STRONGER OF THE TWO AND IS DIVING SOUTHEASTWARD FROM THE
NORTHERN PLAINS INTO THE UPPER MIDWEST. THE SOUTHERN WAVE IS MOVING
ACROSS THE ARKLATEX REGION. IN THE LOWER LEVELS...850MB FLOW IS
SHIFTING TO MORE SOUTHWESTERLY AHEAD OF A TROUGH THAT EXTENDS FROM
LAKE MICHIGAN ACROSS THE TENNESSEE VALLEY. WEAK WAA AHEAD OF THIS
FEATURE HAS INITIATED...WITH 850 TEMPS AT -1C TO 1C ACROSS THE AREA
AND A WARMER TEMPS AT 2-3C SURGING NORTHWARD INTO SOUTHERN WV. AT
THE SURFACE...A 1009MB LOW IS MOVING INTO WESTERN TN WITH A FRONTAL
BOUNDARY EXTENDING NORTHEAST OF THIS FEATURE INTO SOUTHERN OHIO.
TODAY...THE SURFACE LOW WILL LIFT NORTHEASTWARD INTO THE OHIO
VALLEY AND PHASE WITH THE NORTHERN SHORT WAVE TROUGH AS IT REACHES
WESTERN PA AROUND 00Z TUESDAY. WEAK FORCING FROM 285-300K LAYER
ISENTROPIC LIFT...MID-LEVEL SHORT WAVE ENERGY AND THE LOW WILL BE
SUFFICIENT FOR SHOWERS TO BEGIN PUSHING IN FROM THE SOUTHWEST AROUND
15Z AND CONTINUING THROUGH MUCH OF THE DAY. A MODEL CONSENSUS
INDICATES GENERALLY A FEW HUNDREDTHS TO A TENTH OF AN INCH OF PRECIP
SOUTHWEST OF PITTSBURGH BEFORE 18Z AND THEN AN ADDITIONAL TENTH OF
AN INCH ACROSS THE AREA THROUGH 00Z. THUS...ONLY HAVE A TENTH TO A
QUARTER OF AN INCH FORECAST FOR QPF TODAY. FOR TEMPS...HAVE GONE
WITH THE WARMER NAM SOLUTION SOUTH OF PITTSBURGH AND LAMP GUIDANCE
ELSEWHERE.
FOR PRECIP TYPE TODAY...GFS/NAM/ECMWF ARE ALL IN AGREEMENT IN THE
LOW REMAINING RELATIVELY WEAK AS IT TRACKS ALONG THE OHIO RIVER.
DESPITE MODEL SIMILARITIES IN SURFACE LOW TRACK AND INTENSITY WITH
THIS INITIAL LOW...SOUNDINGS INDICATE VARYING THERMAL
PROFILES...MAKING FOR A CHALLENGING PRECIP TYPE FORECAST TODAY.
THE BEGINNING OF PRECIP HAS TRENDED SLOWER...WHICH HAS FAVORED
SURFACE TEMPS WARMING ENOUGH THIS MORNING FOR MOSTLY RAIN IN
EASTERN OHIO AND NORTHERN WV. THE EXCEPTION WOULD BE ACROSS THE
EASTERN RIDGES...WHERE COLD AIR DAMMING WILL KEEP TEMPS BELOW
FREEZING AND THUS ALLOW FOR LIGHT FREEZING RAIN AND LIGHT ICE
ACCUMULATION. 00Z THERMAL PROFILES SUPPORT MORE OF A MIX OF SLEET
AND SNOW WITH FREEZING RAIN ACROSS THE RIDGES. ALONG THE I-80
CORRIDOR...PRECIP IS FORECAST TO REMAIN MOSTLY SNOW AS DENDRITIC
GROWTH ZONE BECOMES SATURATED AND MELTING LAYER IS TOO WEAK. ANY
ICE ACCUMULATION ACROSS THE RIDGES WILL BE LIGHT...LESS THAN A
TENTH OF AN INCH. SNOW AND SLEET MAY MIX IN FOR LESS THAN AN INCH
OF ADDITIONAL ACCUMULATION FOR THE RIDGES. PRIMARILY NORTH OF
I-80...1-2 INCHES OF SNOW ACCUMULATION IS FORECAST.
PRESTON COUNTY HAS BEEN ADDED TO THE FREEZING RAIN ADVISORY THIS
MORNING...AS RADIATIONAL COOLING HAS MADE VALLEYS ESPECIALLY
SUSCEPTIBLE TO A LIGHT ICING TODAY. WILL NEED TO CONTINUE TO
MONITOR RADAR TRENDS FOR THE POSSIBLE EXPANSION OF THE ADVISORY TO
OTHER LOCATIONS.
TONIGHT...THE SURFACE LOW WILL PULL EAST OF THE AREA. GFS/NAM
MODEL SOUNDINGS SUPPORT DRIZZLE/FREEZING DRIZZLE BEHIND THE LOW TONIGHT
ACROSS THE AREA WITH A DRY DENDRITIC GROWTH ZONE. FREEZING DRIZZLE
WILL BE CONFINED TO MOSTLY LOCATIONS NORTH AND EAST OF PITTSBURGH
WITH LOWS BELOW FREEZING THERE. WITH THIS IN MIND...THE FREEZING RAIN
ADVISORY HAS BEEN EXTENDED TO MIDNIGHT TONIGHT FOR THE RIDGES OF WV/MD.
LOWS TONIGHT ARE CLOSE TO LAMP GUIDANCE...RANGING FROM THE UPPER
20S TO LOWER 30S ACROSS MOST OF THE AREA.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
MODELS ARE IN AGREEMENT THAT A FEW LINGERING SNOW SHOWERS WILL BE
POSSIBLE ACROSS THE RIDGES EARLY ON CHRISTMAS DAY AS LOW-LEVEL
MOISTURE LINGERS IN THE WAKE OF THE LOW. HOWEVER...WEAK HIGH PRESSURE
PASSING NORTHWEST OF THE AREA WILL ALLOW MOST OF THE AREA A BRIEF
RESPITE FROM PRECIPITATION BEFORE THE NEXT SYSTEM APPROACHES FROM
THE SOUTHWEST.
A MODEL CONSENSUS CURRENTLY INDICATES A DEEP TROUGH ENTERING THE
CENTRAL PLAINS ON TUESDAY AND CLOSING OFF INTO A LOW. THIS CLOSED
LOW IS PROGGED TO TRACK ACROSS THE TN VALLEY TUESDAY NIGHT INTO
WEDNESDAY. THERE ARE STILL A RANGE OF SOLUTIONS WITH THE TRACK OF
THIS SYSTEM...AND PRECIPITATION TYPE WILL BE HIGHLY DEPENDENT ON
THE TRACK AND HOW A WARM WEDGE WRAPS IN FROM THE SOUTHEAST AND AROUND
THE LOW. SOLUTIONS RANGE FROM THE COLDER ECMWF TAKING THE SURFACE LOW
SOUTHEAST OF THE RIDGES TO THE NAM TRACKING THE LOW INTO WESTERN
PA.
FUTURE FORECASTS WILL NEED TO MONITOR HOW WARM AIR WRAPS INTO THE
LOW...AS THIS WILL DRIVE THE PRECIP TYPE. CURRENT FORECAST
REFLECTS THE WARM 850MB WEDGE OF AIR ADVECTING INTO SOUTHWEST PA.
THIS WOULD LEAD TO THE PITTSBURGH METRO BEING RIGHT ON THE EDGE OF
THE HEAVY SNOW ACCUMULATION TO THE NORTH...A WINTRY MIX CHANGING
TO RAIN TO THE SOUTH...AND ICE ACCUMULATIONS BETWEEN THE TWO.
THERE IS THE POTENTIAL FOR AN INITIAL SHOT OF HEAVY ACCUMULATING
SNOW ACROSS A GOOD PORTION OF THE AREA...HOWEVER THE DURATION OF
THIS SNOW IS STILL UNCERTAIN. BEST CHANCE FOR OVER 6 INCHES LOOKS
TO BE NORTH OF PITTSBURGH...BUT WILL HOLD OFF ON A WINTER STORM
WATCH FOR NOW WITH STILL SOME UNCERTAINTY ON THE NORTHWARD
PROGRESSION OF THE WARM WEDGE...DRY SLOT...AND POTENTIAL ICE
ACCUMULATIONS. IT SHOULD HOWEVER BE NOTED THAT THIS SYSTEM HAS THE
POTENTIAL TO BRING SNOW AND ICE ACCUMULATION THAT COULD LEAD TO
SIGNIFICANT IMPACTS TO HOLIDAY TRAVEL THE DAY AFTER CHRISTMAS.
WEDNESDAY NIGHT INTO THURSDAY...THE CLOSED LOW WILL SHIFT INTO THE
MID-ATLANTIC...WITH CAA ENSUING IN ITS WAKE. THIS WILL ALLOW FOR
PRECIP TO TURN OVER TO ALL SNOW WEDNESDAY NIGHT...WITH SOME LAKE
EFFECT AND UPSLOPING SNOW SHOWERS CONTINUING INTO THE DAY ON
THURSDAY.
FOR TEMPS...HIGHS ON CHRISTMAS WILL BE NEAR NORMAL SEASONAL VALUES
WITH LITTLE THERMAL ADVECTION. WAA DEPENDENT ON THE LOW COULD
BRING TEMPS AROUND 10 DEGREES ABOVE NORMAL SOUTH OF
PITTSBURGH...WITH NEAR SEASONAL NORMALS ELSEWHERE. BEHIND THE
LOW...TEMPS WILL BE AROUND 5 DEGREES BELOW NORMAL.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
BLEND OF GEFS/NAEFS/HPC CHARTS DEPICT A HIGH PRESSURE BUILDING
INTO THURSDAY NIGHT INTO FRIDAY. SFC LOW WILL MOVE ACRS THE OH VLY
SAT...WITH AN UL TROF FOR SUN. A CHC OF SNOW SHOWERS RETURNS FOR
THESE SYSTEMS. OVERALL TEMPS EXPD TO AVG BLW NORMAL THRU THE PD.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
THICKENING HIGH CLOUDS WILL QUICKLY BE REPLACED BY LOW MVFR CIGS
ON MONDAY AFTERNOON. A RATHER DISJOINTED AREA OF DISTURBED WEATHER
WILL MOVE ACROSS THE AREA...WITH THE SOUTHERN TERMINALS FALLING
INTO A WARMER REGIME THAN THE NORTHERN TERMINALS. AS SUCH...LIGHT
RAIN WILL TRANSITION TO DRIZZLE TOMORROW NIGHT IN THE
SOUTH...WHILE LIGHT SNOW WILL END AS A PERIOD OF DRIZZLE OR
FREEZING DRIZZLE TO THE NORTH. IFR CONDITIONS ARE HIGHLY LIKELY
WITH THE PASSAGE OF THE SYSTEM AS LOW LEVEL MOISTURE SEEMS LIKELY
TO LINGER WELL BEYOND SIGNIFICANT PRECIPITATION.
.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
LIGHT RAIN AND SNOW TAPERING OFF MONDAY NIGHT INTO TUESDAY MORNING
COULD BRIEFLY CAUSE MVFR CONDITIONS BEFORE VFR RETURNS FOR THE
REST OF CHRISTMAS DAY.
ANOTHER LOW PRESSURE SYSTEM APPROACHING FROM THE SOUTHWEST ON
WEDNESDAY WITH MIXED PRECIPITATION WILL CAUSE IFR CONDITIONS
THROUGH THURSDAY BEFORE VFR CONDITIONS RETURN ON FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FREEZING RAIN ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MDZ001.
OH...NONE.
PA...NONE.
WV...FREEZING RAIN ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR WVZ023-
041.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...WOODRUM
AVIATION...FRIES
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
237 AM EST MON DEC 24 2012
.SYNOPSIS...
A WEAK SURFACE LOW WILL PUSH ACROSS THE AREA TODAY...BRINGING A
LIGHT WINTRY MIX OF PRECIPITATION ACROSS THE RIDGES AND NORTH OF
PITTSBURGH WITH MOSTLY RAIN ELSEWHERE. WEAK HIGH PRESSURE WILL PASS
NORTHWEST OF THE AREA AND ALLOW FOR A MOSTLY DRY CHRISTMAS DAY. THE
NEXT LOW WILL THE BRING A WINTRY MIX ACROSS THE AREA WEDNESDAY INTO
THURSDAY.
&&
.NEAR TERM /THROUGH TODAY/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A PAIR OF SHORT WAVES
UPSTREAM ALONG THE SAME AXIS OF A BROAD UPPER TROUGH. THE NORTHERN
WAVE IS THE STRONGER OF THE TWO AND IS DIVING SOUTHEASTWARD FROM THE
NORTHERN PLAINS INTO THE UPPER MIDWEST. THE SOUTHERN WAVE IS MOVING
ACROSS THE ARKLATEX REGION. IN THE LOWER LEVELS...850MB FLOW IS
SHIFTING TO MORE SOUTHWESTERLY AHEAD OF A TROUGH THAT EXTENDS FROM
LAKE MICHIGAN ACROSS THE TENNESSEE VALLEY. WEAK WAA AHEAD OF THIS
FEATURE HAS INITIATED...WITH 850 TEMPS AT -1C TO 1C ACROSS THE AREA
AND A WARMER TEMPS AT 2-3C SURGING NORTHWARD INTO SOUTHERN WV. AT
THE SURFACE...A 1009MB LOW IS MOVING INTO WESTERN TN WITH A FRONTAL
BOUNDARY EXTENDING NORTHEAST OF THIS FEATURE INTO SOUTHERN OHIO AND
BECOMING MORE WASHED OUT INTO SW PA.
TODAY...THE SURFACE LOW WILL LIFT NORTHEASTWARD INTO THE OHIO
VALLEY AND PHASE WITH THE NORTHERN SHORT WAVE TROUGH AS IT REACHES
WESTERN PA AROUND 00Z TUESDAY. WEAK FORCING FROM 285-300K LAYER
ISENTROPIC LIFT...MID-LEVEL SHORT WAVE ENERGY AND THE LOW WILL BE
SUFFICIENT FOR SHOWERS TO BEGIN PUSHING IN FROM THE SOUTHWEST AROUND
15Z AND CONTINUING THROUGH MUCH OF THE DAY. A MODEL CONSENSUS
INDICATES GENERALLY A FEW HUNDREDTHS TO A TENTH OF AN INCH OF PRECIP
SOUTHWEST OF PITTSBURGH BEFORE 18Z AND THEN AN ADDITIONAL TENTH OF
AN INCH ACROSS THE AREA THROUGH 00Z. THUS...ONLY HAVE A TENTH TO A
QUARTER OF AN INCH FORECAST FOR QPF TODAY. FOR TEMPS...HAVE GONE
WITH THE WARMER NAM SOLUTION SOUTH OF PITTSBURGH AND LAMP GUIDANCE
ELSEWHERE.
FOR PRECIP TYPE TODAY...GFS/NAM/ECMWF ARE ALL IN AGREEMENT IN THE
LOW REMAINING RELATIVELY WEAK AS IT TRACKS ALONG THE OHIO RIVER.
DESPITE MODEL SIMILARITIES IN SURFACE LOW TRACK AND INTENSITY WITH
THIS INITIAL LOW...SOUNDINGS INDICATE VARYING THERMAL
PROFILES...MAKING FOR A CHALLENGING PRECIP TYPE FORECAST TODAY.
THE BEGINNING OF PRECIP HAS TRENDED SLOWER...WHICH HAS FAVORED
SURFACE TEMPS WARMING ENOUGH THIS MORNING FOR MOSTLY RAIN IN
EASTERN OHIO AND NORTHERN WV. THE EXCEPTION WOULD BE ACROSS THE
EASTERN RIDGES...WHERE COLD AIR DAMMING WILL KEEP TEMPS BELOW
FREEZING AND THUS ALLOW FOR LIGHT FREEZING RAIN AND LIGHT ICE
ACCUMULATION. 00Z THERMAL PROFILES SUPPORT MORE OF A MIX OF SLEET
AND SNOW WITH FREEZING RAIN ACROSS THE RIDGES. ALONG THE I-80
CORRIDOR...PRECIP IS FORECAST TO REMAIN MOSTLY SNOW AS DENDRITIC
GROWTH ZONE BECOMES SATURATED AND MELTING LAYER IS TOO WEAK. ANY
ICE ACCUMULATION ACROSS THE RIDGES WILL BE LIGHT...LESS THAN A
TENTH OF AN INCH. SNOW AND SLEET MAY MIX IN FOR LESS THAN AN INCH
OF ADDITIONAL ACCUMULATION FOR THE RIDGES. PRIMARILY NORTH OF
I-80...1-2 INCHES OF SNOW ACCUMULATION IS FORECAST.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
PER RECENT SREF MODEL OUTPUT...CONTINUED MENTION OF PRECIPITATION
TONIGHT...CHRISTMAS EVE...AS PASSING LOW PRESSURE CENTER WILL
NOT EXIT NORTHEAST UNTIL LATE MONDAY NIGHT.
PRECIPITATION TYPE WILL VARY FROM RAIN MOST PLACES TO LIGHT SNOW
ACROSS THE I-80 CORRIDOR AND LINGERING PATCHES OF LIGHT FREEZING
DRIZZLE OR DRIZZLE FOR THE HIGHER WV-MD MOUNTAINS. SREF MODEL PROFILES
SUGGEST DRYING ALOFT CAN LEAD TO THE LIGHT PRECIPITATION BECOMING
LITTLE MORE THAN A LIGHT DRIZZLE BY MIDNIGHT...UNLESS SEEDER
FEEDER MECHANISMS COME INTO PLAY. WHERE SURFACE TEMPERATURES SLIP
BELOW FREEZING...THIS COULD BE LIGHT FREEZING DRIZZLE.
SREF MODEL OUTPUT SHOWS A DRY BREAK FOR CHRISTMAS DAY DUE TO
PASSING HIGH PRESSURE.
LOWS CHRISTMAS MORNING WILL BE NEAR OR SLIGHTLY COLDER THAN
FREEZING. HIGHS CHRISTMAS AFTERNOON CAN BE NEAR OR SLIGHTLY WARMER
THAN NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
DEVELOPING LOW PRES WL MOVE NE FM THE MS VLY RGN TUE NT...BRINGING A MIX
OF PCPN TO THE AREA LATE TUE NT THRU WED. STILL CONSIDERABLE
UNCERTAINTY IN THE DETAILS OF THIS SYSTEM. REGENERATION OF THE LOW
IS EXPECTED OVR NRN VA WED EVE. NAM DELAYS THIS REGENERATION
PROCESS...WHICH RESULTS IN WARMER AIR WRAPPED INTO THE SYSTEM WED.
BELIEVE NAM IS TAKING TOO LONG TO DEPICT THIS TRANSITION GIVEN
VERTICAL STACKING OF SFC AND UL LOWS ERLY WED...SO LEANED CLOSER TO
SREFS AND GFS FOR FCST DETAILS.
THIS RESULTS IN A WINTRY MIX OF FZRA...RAIN...SLEET AND SNOW WED
INTO WED EVE. CRITICAL THICKNESSES AND SOUNDING PROFILES INDICATE
MUCH OF THE PCPN WL CHG TO RAIN FOR AREAS FM PIT SWD. EXPECT MORE
SNOW INITIALLY N OF PIT...EVENTUALLY MIXING WITH SLEET/RAIN/FZRA.
WL MONITOR FOR CHANGING DETAILS NEXT COUPLE OF DAYS.
OTRW...COLDER AIR MOVING IN BEHIND THE LOW WED NT-THU WL RESULT
IN SNOW SHOWERS...WITH SOME ACCUMULATION LIKELY ESP IN LK ENHANCED
AND HIGHER TERRAIN AREAS. BLEND OF GEFS/NAEFS/HPC CHARTS DEPICT A
SFC LOW MOVG ACRS THE OH VLY SAT...WITH AN UL TROF FOR SUN. A CHC
OF SNOW SHOWERS RETURNS FOR THESE SYSTEMS. OVERALL TEMPS EXPD TO
AVG BLW NORMAL THRU THE PD.
&&
.AVIATION /07Z MONDAY THROUGH FRIDAY/...
THICKENING HIGH CLOUDS WILL QUICKLY BE REPLACED BY LOW MVFR CIGS
ON MONDAY AFTERNOON. A RATHER DISJOINTED AREA OF DISTURBED WEATHER
WILL MOVE ACROSS THE AREA...WITH THE SOUTHERN TERMINALS FALLING
INTO A WARMER REGIME THAN THE NORTHERN TERMINALS. AS SUCH...LIGHT
RAIN WILL TRANSITION TO DRIZZLE TOMORROW NIGHT IN THE
SOUTH...WHILE LIGHT SNOW WILL END AS A PERIOD OF DRIZZLE OR
FREEZING DRIZZLE TO THE NORTH. IFR CONDITIONS ARE HIGHLY LIKELY
WITH THE PASSAGE OF THE SYSTEM AS LOW LEVEL MOISTURE SEEMS LIKELY
TO LINGER WELL BEYOND SIGNIFICANT PRECIPITATION.
.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
LIGHT RAIN AND SNOW TAPERING OFF MONDAY NIGHT INTO TUESDAY MORNING
COULD BRIEFLY CAUSE MVFR CONDITIONS BEFORE VFR RETURNS FOR THE
REST OF CHRISTMAS DAY.
ANOTHER LOW PRESSURE SYSTEM APPROACHING FROM THE SOUTHWEST ON
WEDNESDAY WITH MIXED PRECIPITATION WILL CAUSE IFR CONDITIONS
THROUGH THURSDAY BEFORE VFR CONDITIONS RETURN ON FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FREEZING RAIN ADVISORY FROM 8 AM THIS MORNING TO 6 PM EST THIS
EVENING FOR MDZ001.
OH...NONE.
PA...NONE.
WV...FREEZING RAIN ADVISORY FROM 8 AM THIS MORNING TO 6 PM EST THIS
EVENING FOR WVZ041.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
136 AM EST MON DEC 24 2012
.SYNOPSIS...
LOW PRESSURE WILL TRACK NORTHEAST ACROSS THE MID ATLANTIC STATES
CHRISTMAS EVE...WITH HIGH PRESSURE REBUILDING OVER THE AREA FOR
CHRISTMAS DAY. A STRONGER AREA OF LOW PRESSURE TRACKS THROUGH THE
TENNESSEE VALLEY CHRISTMAS NIGHT...THEN CONTINUES ACROSS THE MID
ATLANTIC ON WEDNESDAY...WITH ITS ASSOCIATED COLD FRONT PUSHING
OFF THE COAST EARLY THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LATEST WX ANALYSIS REVEALS BROAD AREA OF SFC HIGH PRESSURE, THE
CENTER OF WHICH WAS ORIENTED ALONG THE ATLANTIC COAST OF FLORIDA
AND OFF THE SOUTHEAST COAST. ALOFT, UA ANALYSIS SHOWS QUASI-ZONAL
FLOW CONTINUES ACROSS THE EASTERN 2/3 OF THE COUNTRY. FAST FLOW
ALOFT HAS ALLOWED FOR QUICK INCREASE OF MID TO HIGH LEVEL
CLOUDINESS AHEAD OF A DISTURBANCE ACROSS GA AND UPSTATE SC THIS
EVE, WITH INCREASING CLOUDS OVER THE SOUTHERN HALF OF THE FORECAST
AREA. FARTHER NORTH, CLEAR/MCLEAR SKY PERSISTS OVER FAR NORTHERN
TIER OF CWA. THIS CLEARING IS ALLOWING FOR BETTER RADIATING
CONDITIONS AND SIGNIFICANTLY COOLER CONDITIONS OVER THE LWR
EASTERN SHORE AND FARTHER NORTH INTO THE NORTH MID-ATLANTIC.
RADAR MOSAIC SHOWING SOME VERY LIGHT RETURNS OVER WESTERN
CAROLINAS IN ASSOCIATION WITH SOME WEAK FORCING AHEAD OF THE
SYSTEM. HOWEVER, ANTECEDENT DRY LLVL AIRMASS, AND DOWNSLOPE (WEST)
FLOW ALOFT, IS NOT ALLOWING MUCH OF THIS ACTIVITY TO REACH THE
GROUND THUS FAR. RUC SEEMS TO BE HANDLING THIS SLOWER ONSET OF
POPS WELL OVER OUR REGION, AND HAVE LEANED ON ITS GUIDANCE
OVERNIGHT. SINCE ACCUMULATING PCPN APPEARS RATHER UNLIKELY
OVERNIGHT, HV REMOVED MENTION OF POPS BEFORE 12Z/7AM MONDAY, BUT
NOT OUT OF THE QUESTION TO SEE A FEW SPRINKLES ACROSS THE PIEDMONT
NEAR DAWN MONDAY MORNING. ALL MINIMA ACROSS THIS AREA WILL BE
ABOVE FREEZING AND MDL THERMAL PROFILES RMN WARM ENOUGH TO
PRECLUDE ANY PRECIP TYPE ISSUES OVER THE LOCAL AREA WITH ANY LGT
PCPN THAT OCCURS. EARLY MORNING LOW TEMPS TO RANGE FROM U20S/NR 30
ACROSS THE EASTERN SHORE TO U30S/NR 40 ACROSS SE VA/NE NC.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
LO PRES CONTS TO MOVE TO THE NE TWD/INTO NEW ENG MON AFTN/NGT.
ASSOCIATED MSTR AXIS TO SWING (W-E) ACRS THE FA DURG MON...W/
HIGHEST POPS (60-70%) NW PORTION OF FA...TAPERING TO TO 25-30%
XTRM SE VA/CSTL NE NC. QUITE THE TEMP GRADIENT XPCD ON MON...W/ HI
TEMPS FM THE L/M40S FAR NW...TO THE M/U50S SE. DRYING OUT QUICKLY
FM SW TO NE MON NGT...LEADING TO DRY WX ON TUE W/ TEMPS AVGG A
FEW DEGS F ABV NRML (TOPPING OUT IN THE L/M50S).
NEXT STRONGER LO PRES SYS WILL BE DVLPG INVOF W/CNTRL GULF STATES
LT TUE INTO TUE NGT...THEN IS FCST TO TRACK TO THE NE INTO THE ERN
OH VLY BY WED AFTN. MDLS CONT TO TREND WARMER AND HAVE PARENT LO W
OF THE MTNS (ON ITS WAY NE). WRMFNT TO LIFT N INTO/THROUGH THE FA ON
WED AIDED BY INCRSG SE THEN S WNDS. MAIN AREA OF MID LVL DYNAMICS
TO REACH THE FA WED AFTN AS RIBBON OF HIGHER SFC DEWPTS/LLVL
INSTABILITY WOULD BE SURGING NWD. THEREFORE...THOUGH IT BEING LT
DEC...CONCERN IS FOR PSBL CNVTN AND PD OF MDT/HVY RA AHD OF/WITH
CDFNT TO THE AREA DURG WED AFTN. WILL (STRNG) T PTNTL BE INCRSD BY
TRIPLE POINT LO MOVING NNE OVR THE PIEDMONT? FOR NOW...WILL HAVE
80% POPS...AND INCLUDE CHC T FOR SRN HALF OF VA/NE NC (WED AFTN).
HI TEMPS WED FM THE U40S/ARND 50F NW (WELL INLAND)...TO THE U60S/ARND
70F IN XTRM SE VA/CSTL NE NC.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
DECENT MODEL AGREEMENT WED NIGHT WITH A QUICK COLD FRONTAL PASSAGE
AS DEEPENING LOW PRESSURE QUICKLY MOVES NORTHEAST OF THE REGION.
KEPT CHC EVE POPS AHEAD OF FROPA. CAA KICKS IN ALLOWING DRY SLOT TO
PUNCH NE AND CUT PCPN OFF AFTR MIDNITE. LOWS IN THE 30S.
THURSDAY APPEARS TO BE ANOTHER DAY LIKE SATURDAY WAS. STRNG PRS
GRDNT ARND DEPARTING LOW RESULTS IN A BREEZY/WINDY DAY WITH PTNTL
FOR GUSTS OVER 30 MPH INLAND AND GALE FORCE WINDS OVER THE WATERS.
PT SUNNY AS COLD AIR ALOFT RESULTS IN SC DVLPMNT DRNG THE DAY. KEPT
IT DRY WITH HIGHS IN THE 40S TO L50S SERN CNTYS.
HIGH PRS BUILDS INTO THE AREA THURS NITE & FRI. THIS KEEPS IT DRY
WITH DMNSHG WINDS. LOWS THURS NITE M20S-L30S. HIGHS FRI IN THE 40S.
MODELS THEN DIVERGE BY NEXT WEEKEND AS YET ANTHR (WEAKER) SYSTM
EJECTS OUT OF SW THEN MOVES ACROSS THE SRN CONUS. ECMWF QUICKER IN
BRINGING PCPN IN FRI NITE WITH THE GFS GIVING THE REGION THE OLD
SPLIT IN PCPN BATCHES SAT. WILL KEEP LOW CHC (LIQUID) POPS IN FOR
SAT. SOME P-TYPE ISSUES ARE PSBL IF PCPN COMES IN A BIT FASTER FRI
NITE. LOWS FRI NITE U20S-M30S. HIGHS SAT IN THE 40S AND 50S. COLDER
BEHIND SYSTM SUNDAY. LOWS SAT NITE M20S-M30S. HIGHS SUN IN THE
40S.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO INCREASE EARLY THIS
MORNING...AS LIGHT WSW WINDS SHIFT TO THE NE BETWEEN 10-12Z. WEAK LOW
PRESSURE MOVES FROM THE TENNESSEE AND OHIO VALLEYS AND TURNS
WINDS TO THE SE OR S LATER THIS AFTN/EVENING. WILL CARRY -RA IN
THE TAFS AT SOME PT TODAY (EARLIEST AT KRIC). THE RAIN IS
EXPECTED TO BE LIGHT AND VSBYS/CIGS LOOK TO DROP TO MVFR RANGE AT
WORST. THERE COULD BE A FEW HRS OF IFR CIGS/ < 1 K FT TONIGHT
BETWEEN 03-09Z/25 IN LIGHT SW FLOW AND LINGERING LOW LEVEL MOISTURE.
OTHERWISE SKIES CLEAR OUT FOR CHRISTMAS MORNING W/ VFR CONDITIONS
PREVAILING UNTIL A MORE SIGNIFICANT WEATHER SYSTEM BEGINS TO AFFECT
THE REGION LATE TUE NIGHT THRU WED WITH A FAIRLY LONG PERIOD OF
RAIN AND LOWS CIGS/VSBYS LIKELY AT KRIC/SBY (MORE VARIABLE
CONDITIONS POSSIBLE FOR KPHF/KORF/KECG WITH PRECIP BECOMING MORE
SHOWERY). BREEZY E/SE FLOW WED AFTN GRADUALLY TURNS SSW LATE WED
NIGHT INTO THURSDAY MORNING.
&&
.MARINE...
SW WINDS 10-15 KNOTS SHOULD SLOWLY TURN TO THE NNE BEFORE 12Z AS A
WEAK COLD FRONT APPROACHES AND THEN MOVES THROUGH DURING THE EARLY
MORNING HOURS. A BRIEF SURGE DOWN THE BAY (FROM THE NORTH) PSBL
FOLLOWING THE FRONTAL PASSAGE DURING THE PREDAWN HOURS...EXPECT
THIS TO REMAIN AOB 15 KTS. VRBL WIND FLOW AOB 15 KTS SETS UP MON
AND TUES AS NEXT SYSTEM MOVES ACROSS THE AREA.
NEXT STRONGER SYSTEM PROGGED TO MOVE ACROSS THE RGN BY MID WEEK.
INCRSG E-SE FLOW AHEAD OF IT WILL LIKELY RESULT IN SCA HEADLINES
BEGINNING WED. STRONG CAA BEHIND A COLD FRONT RESULTS IN A STRONG
SCA WED NITE AND THURS WITH POTENTIAL FOR GALE FORCE GUSTS THURS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...ALB/MAM
NEAR TERM...ALB/MAM
SHORT TERM...ALB
LONG TERM...MPR
AVIATION...LKB
MARINE...MPR
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
436 PM EST MON DEC 24 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 434 PM EST MON DEC 24 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
ONTARIO WITH A TROUGH EXTENDING INTO THE WESTERN GREAT LAKES. A
SHORTWAVE TROUGH WAS LOCATED OVER LOWER MI WHILE UPSTREAM A WEAKER
SHRTWV EXTENDED FROM THE SRN END OF JAMES BAY TO NEAR KINL. ALTHOUGH THE
STRONGEST 700-300 MB QVECTOR CONV REMAINED SOUTHEAST OF UPPER MI
WHILE...SOME WEAK TO MODERATE FORCING LINGERING OVER THE AREA
SUPPORTED AREAS OF LIGHT SNOW WITH VISIBILITIES GENERALLY AT OR
ABOVE 5SM. NW LOW LEVEL WINDS WITH 850 MB TEMPS AROUND -15C ALSO
SUPPORTED SOME LIGHT LES BANDS. A SIGNIFICANT LIMITING FACTOR FOR
LES INTENSITY WAS LOW INVERSION HEIGHTS AROUND 4K FT AND INFLUX OF
DRIER AIR BELOW THE INVERSION.
TONIGHT...INCREASING LOW-LVL CONVERGENCE AIDED BY DEVELOPING LAND
BREEZES SHOULD PROVIDE ADDITIONAL FOCUS FOR LES INTO ERN ALGER/NRN
SCHOOLCRAFT AND PERHAPS OVER THE PORCUPINE MOUNTAINS OVER THE WEST.
THE DRY AIR UPSTREAM AND LOW INVERSION HEIGHTS WILL LIMIT
AMOUNTS...ESPECIALLY OVER THE WEST...TO GENERALLY AN INCH OR LESS.
GREATER POPS WERE INCLUDED OVER THE ERN CWA WHERE THE LONGER FETCH
WILL HELP KEEP INVERSION HEIGHTS IN THE 5K-7K FT RANGE AND CLOUD
SUPPORT SLIGHTLY GREATER SNOWFALL AMOUNTS OF AN INCH OR TWO.
LES WILL CONTINUE INTO CHRISTMAS DAY AS 850 MB TEMPS REMAIN NEAR
-14C BUT SHOULD DIMINISH AS WINDS BACK TO WNW WITH SLOWLY LOWERING
INVERSION HEIGHTS AND MORE ANTICYCLONIC/DIVERGENT LOW LEVEL FLOW.
SNOWFALL INTENSITY/AMOUNTS WILL REMAIN GREATEST OVER THE EAST WHERE
AN ADDITIONAL INCH MAY ACCUMULATE.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 434 PM EST MON DEC 24 2012
NOT A LOT OF EXCITING WEATHER TO GO IN DEPTH ABOUT FOR THE LONG TERM
PERIOD /TUESDAY NIGHT THROUGH NEXT MONDAY/. WE WILL BE DOMINATED BY
NORTHERLY WINDS FOR MUCH OF THE PERIOD WITH SLIGHT TO LOW CHANCE
POPS NEAR LAKE SUPERIOR...AS THE STORM TRACK CONTINUES TO BE WELL TO
OUR S.
TUESDAY NIGHT SHOULD BE ONE OF THE COLDEST IN A WHILE...WITH A FEW
LOCATIONS OVER INTERIOR W PORTIONS OF UPPER MI FALLING BELOW 0
THANKS TO A POCKET OF CLEARING NOTED BY SOME OF THE SMALLER SCALE
MODELS.
DID INCREASE THE FCST MODEL CONSENSUS POPS FOR SATURDAY NIGHT
THROUGH MONDAY...HEDGING THE FCST CLOSER TO THE ECMWF AND SLIGHTLY
HIGHER CONFIDENCE IN COLD AIR ROTATING IN ON MAINLY NW WINDS. THE
OUTLIER WAS THE GFS...PARTICULARLY FROM SUNDAY ON AS IT BROUGHT A
SFC LOW FROM CENTRAL CANADA TO ONTARIO SUNDAY NIGHT. A WEAKENING SFC
TROUGH CONTINUED FOR THE GFS...EXTENDING W FROM THE EXITING LOW OFF
THE COAST OF MAINE. THE ECMWF HAD FAIRLY STEADY 850MB TEMPS OF -15
TO -20C FROM SATURDAY NIGHT THROUGH MONDAY...WITH AT LEAST LIMITED
MOISTURE TO BRING IN A GOOD CHANCE OF SNOW SHOWERS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1247 PM EST MON DEC 24 2012
WITH A STRONG INVERSION OVER THE AREA...THE STRATUS CLOUDS WILL
PERSIST THROUGH TONIGHT. LIGHT SNOW WITH VSBY DOWN TO AROUND 3SM AT
IWD IS EXPECTED TO MOVE OUT EARLY THIS AFTERNOON. OTHWERWISE...A NW
FLOW WILL BRING SOME OCCASIONAL LIGHT LAKE EFFECT SNOW TO THE TAF
SITES BUT VSBYS SHOULD NOT BE RESTRICTED BY IT. SO...EXPECT MVFR
CIGS AT BOTH KCMX AND KSAW THROUGH THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 434 PM EST MON DEC 24 2012
A HIGH PRESSURE RIDGE BUILDING IN FROM THE CANADIAN PRAIRIES TODAY
AND TONIGHT WILL LINGER THROUGH MUCH OF THE WEEK...KEEPING WINDS
AT OR BELOW 25 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
337 PM EST MON DEC 24 2012
.SHORT TERM...THIS EVENING AND TONIGHT
UPSTREAM LIGHT SNOW AND VIRGA HAVE BEEN STEADILY PUSHING INTO THE
AREA AHEAD OF THE COMPACT MID-LEVEL SHORTWAVE ROTATING ACROSS THE
LOWER PENINSULA THIS AFTERNOON. FOR SEVERAL HOURS NOW, A PERIOD OF
VIRGA HAS PRECEDED A RATHER BRIEF PERIOD OF LIGHT TO MODERATE
SNOWFALL.
ANALYSIS OF OBSERVATIONS AND SHORT TERM MODEL DATA INDICATE THAT THE
ONGOING SNOWFALL/VIRGA IS STRONGLY TIED TO TWO SEPARATE FEATURES.
THE FIRST, AND PRIMARY TO AFFECT SOUTHEAST MICHIGAN, IS THE BROAD
CORRIDOR OF ASCENT ASSOCIATED WITH DCVA PRECEDING THE WAVE ITSELF.
THE SECOND, MAINLY AFFECTING LOCATIONS SOUTH OF THE BORDER...PERHAPS
AS FAR NORTH AS THE I-94 CORRIDOR...IS A DEEP FRONTOLYTIC
CIRCULATION LEADING THE NOSE OF THE ASSOCIATED 80-KT JET STREAK.
THIS REGION OF FORCED COLD ASCENT HAS ALSO DRAWN UPON A POCKET OF WEAK
MID-LEVEL INSTABILITY TO PRODUCE A STRONGER CONVECTIVE RESPONSE TO
THE SOUTH AND OCCASIONAL ECHOES OF 40DBZ OVER NORTHERN IN.
THE NORTHWARD MIGRATION OF THE ELEVATED FRONTAL ZONE/THETA-E RIDGE
AS WELL AS SUB-850 EASTERLY MOISTURE ADVECTION WILL HELP TO ERODE
THE H85-H7 DRY LAYER APPARENT ON THIS MORNING`S 12Z DTX SOUNDING AND
ALLOW FOR A SUBSEQUENT EXPANSION OF LIGHT SNOW AND DECREASE IN VIRGA
OVER THE NEXT FEW HOURS. RECENT RADAR TRENDS CONFIRM THESE
EXPECTATIONS (AND YESTERDAY`S NMM CORE SOLUTIONS). RUC ANALYSIS
SUGGESTS THAT WHILE A BRIEF PERIOD OF CONVECTIVE PRECIP WILL BE
POSSIBLE ACROSS THE SOUTHERN CWA, THE BULK OF THE EVENT WILL LIKELY
TAKE PLACE ACROSS THE HEART OF THE FORECAST AREA AND WILL BE
CHARACTERIZED BY A FEW HOURS OF LIGHT SNOW WITH EMBEDDED MODERATE
BANDING OWING TO BOTH A VERY WEAKLY STATICALLY STABLE ATMOSPHERE
ABOVE THE LOW-LEVEL FRONT AND MARGINAL MID-LEVEL INSTABILITY. THE
FORECAST HAS THEREFORE BEEN AMENDED TO REFLECT A HIGHER POP SCENARIO
FROM APPROXIMATELY LIVINGSTON TO TO LAPEER COUNTIES WHERE A
WIDESPREAD HALF INCH OR SO IS STILL POSSIBLE. LOCATIONS AFFECTED BY
SAID BANDING WILL SEE A PORTION OF THE SNOW ACCUMULATE MORE QUICKLY
AS VSBYS FALL TO 1-2 MILES PER UPSTREAM OBS...RESULTING IN THE
POTENTIAL FOR A FEW ISOLATED 1" ACCUMS.
&&
.LONG TERM...
CHRISTMAS DAY WILL BE ON THE TRANQUIL SIDE OVERALL AROUND SE
MICHIGAN LEADING INTO AN ACTIVE PERIOD OF WINTER WEATHER AFTER THE
HOLIDAY. HIGHER END ADVISORY CRITERIA SNOWFALL AMOUNTS AND RATES ARE
ANTICIPATED FOR SE MICHIGAN WEDNESDAY THROUGH WEDNESDAY NIGHT WITH
THE TIMING ON THE DAY AFTER CHRISTMAS AND POTENTIAL TRAVEL IMPACTS
BEING THE NOTABLE ASPECT OF THE EVENT.
THE WEDNESDAY LOW PRESSURE SYSTEM WILL BE PRECEDED BY SOME LAKE
EFFECT SNOW SHOWERS MAKING INLAND PROGRESS OFF LAKE HURON DURING
CHRISTMAS DAY. INLAND PROGRESS COULD BE AS FAR SOUTH AS I-69 AND
WEST TO I-75 ON A SCATTERED BASIS WITH GREATER COVERAGE IN THE THUMB
CLOSER TO THE LAKE. INSTABILITY WILL BE MODEST WITH LAKE TO 850
DELTA-T RUNNING AROUND 15C BUT WITH INVERSION HEIGHT BOOSTED BY SOME
SEEDING FROM MID LEVEL MOISTURE TRAILING TODAY`S WAVE. THE BROAD
INVERTED SURFACE TROUGH WILL PROVIDE A FAVORABLE LOW LEVEL WIND
FIELD FOR FOCUSING NORTHERLY FLOW INTO THE THUMB FOR A FEW HOURS
BEFORE FILLING AND DRYING TOWARD EVENING.
THE MAIN CONCERN IN THE FORECAST REMAINS THE EVOLUTION OF A LARGE
LOW PRESSURE SYSTEM SET TO IMPACT MUCH OF THE COUNTRY EAST OF THE
MISSISSIPPI WEDNESDAY INTO THURSDAY. THIS SYSTEM IS EXPECTED TO
NEGATIVELY IMPACT POST HOLIDAY TRAVEL ACROSS THE REGION WITH
MODERATE SNOW ACCUMULATION REMAINING THE PRIMARY EXPECTATION IN SE
MICHIGAN. SUBJECT UPPER LEVEL ENERGY WAS MORE FULLY INLAND FROM THE
WEST COAST FOR THE MORNING UPPER AIR ANALYSIS, SO IT IS A GOOD SIGN
THAT THE 12Z MODEL CYCLE HAS NOT SHIFTED MUCH OFF OF EARLIER
SOLUTIONS AS THE SYSTEM DEVELOPS OVER THE WESTERN GULF COAST DURING
CHRISTMAS DAY AND DEEPENS INTO THE TENNESSEE VALLEY BY WEDNESDAY
MORNING. AGREEMENT BETWEEN THE NAM, GFS, ECMWF, AND LOCAL WRF GLOBAL
IS EXCELLENT BY THEN ON THE POSITION AND INTENSITY OF THE LARGE
SCALE FEATURES ASSOCIATED WITH THE SYSTEM. THE CANADIAN REMAINS
FASTER/FARTHER EAST IN THE SOLUTION SPACE PERHAPS REPRESENTING THE
STRONG INFLUENCE ON TRACK AND STRENGTH BY THE SOUTHWARD POSITION OF
THE UPPER JET AXIS FROM SOUTHERN CALIFORNIA TO THE CENTRAL GULF
COAST. THERE IS ALSO CONSIDERABLE LOW LEVEL BAROCLINICITY, GULF
MOISTURE, AND WARM SECTOR INSTABILITY IN ADVANCE OF THE WAVE FROM
THE TENNESSEE VALLEY TO THE MID ATLANTIC STATES. ALL OF THIS, ALONG
WITH A NEW ROUND OF UPPER LEVEL HEIGHT FALLS OVER THE WEST COAST,
FAVORS PROGRESSION AND THE TRANSFER OF CYCLOGENESIS TO THE EAST
COAST DURING WEDNESDAY.
CONFIDENCE IN THE MODEL SOLUTIONS ON THE BULK FEATURES DOES NOT GET
US OUT OF THE WOODS ON A WINTER EVENT OR SIMPLIFY THE FORECAST FOR
OUR AREA DURING WEDNESDAY INTO WEDNESDAY NIGHT AS A CONSIDERABLE
AMOUNT OF MOISTURE REMAINS ADVERTISED FOR THE REGION. WITH AN EASY
CALL ON ALL SNOW AS THE PRECIPITATION TYPE, THE QUESTION OF AMOUNT
REMAINS TIED TO THE CHARACTER AND DURATION OF MAX FORCING AND
MICROPHYSICAL ASPECTS OF THE SNOW OVER SE MICHIGAN DURING THE PEAK
OF THE EVENT WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING. THE
TRANSFER OF CYCLOGENESIS TO THE MID ATLANTIC COAST WILL SIPHON AT
LEAST SOME ENERGY AND MOISTURE OUT OF THE GREAT LAKES BUT A WELL
ORGANIZED TROWAL IS SHOWN TO BE IN PLACE OVER OUR AREA WITH A STRONG
HYBRID ATLANTIC/GULF MOISTURE CONVEYOR FEEDING INTO THE NORTH FLANK
OF THE SYSTEM. MODEL FIELDS OF SPECIFIC HUMIDITY INDICATE MORE THAN
ADEQUATE AMOUNTS OF 2-3 G/KG IN THE 850 TO 700 MB LAYER ASSOCIATED
WITH THE TROWAL AXIS. THIS LEAVES DURATION AS THE LIMITING FACTOR AS
FIELDS OF THETA-E INDICATE THE TROWAL SHRINKING EASTWARD QUICKLY BY
MIDNIGHT WEDNESDAY NIGHT. WILDCARDS TO CONSIDER THAT COULD SKEW
AMOUNTS HIGHER INCLUDE THE ACTUAL TIMING OF EAST COAST TRANSFER,
MESOSCALE BANDS WITHIN THE TROWAL, AND LAKE ENHANCEMENT. THE
POTENTIAL FOR LAKE ENHANCEMENT WILL BE THE MOST LIKELY EXTRA
CONTRIBUTOR BUT THAT WILL TEND TO STRETCH THE EVENT WELL INTO
THURSDAY AS SYNOPTIC FORCING WANES. THIS WILL CONTINUE TO BE
EVALUATED BUT THE PREPONDERANCE OF EVIDENCE FOR THIS FORECAST
PACKAGE, ALONG WITH MODEL SOUNDING DERIVED SNOW RATIO AVERAGING
11:1, SUGGESTS STORM TOTALS WILL REMAIN MOSTLY BELOW 6 INCHES DURING
THE 12 TO 18 HOUR EVENT ENDING BY SUNRISE THURSDAY.
AFTER A BREAK DURING THURSDAY AND MOST OF FRIDAY, THE ACTIVE LARGE
SCALE PATTERN WILL CONTINUE WITH THE NEXT PACIFIC SYSTEM REACHING
THE GREAT LAKES TO START THE WEEKEND. EARLY INDICATIONS ARE THIS
SYSTEM WILL BE LESS ORGANIZED AS IT MOVES THROUGH THE GREAT LAKES
BEFORE GAINING STRENGTH ALONG THE EAST COAST TOWARD SUNDAY.
&&
.MARINE...
LIGHT NORTHERLY WINDS TONIGHT OF 15 KNOTS OR LESS WILL TURN EASTERLY
AND BEGIN TO INCREASE ON TUESDAY NIGHT AS A STRONG LOW PRESSURE
SYSTEM LIFTS TOWARD THE REGION FROM THE SOUTH. THE PROLONGED PERIOD
OF ONSHORE FLOW WILL FAVOR ELEVATED WAVE CONDITIONS FOR ALL
NEARSHORE ZONES BETWEEN WEDNESDAY AND THURSDAY MORNING IN ADDITION
TO POTENTIAL FUNNELING INTO SAGINAW BAY. SMALL CRAFT ADVISORIES
APPEAR LIKELY AT THIS TIME. BY WEDNESDAY AFTERNOON INTO WEDNESDAY
NIGHT...GUSTS TO NEAR GALES WILL BE POSSIBLE ACROSS AREA WATERS.
&&
.AVIATION...ISSUED 1227 PM EST MON DEC 24 2012
//DISCUSSION...
STRATUS WILL CONTINUE TO AFFECT ALL THE TAF SITES. CURRENT SATELLITE
IMAGERY IS SHOWING A BRIEF BREAK...HOWEVER THIS BREAK IS SHORT LIVED
AS MORE STATUS MOVES IN FROM THE SOUTH FROM A WEAK LOW PRESSURE
SYSTEM MOVING THROUGH THE OHIO VALLEY. THIS SYSTEM IS EXPECTED TO
BRING LIGHT SNOW TO FROM PTK SOUTHWARD...WITH THE NORTHERN TAF SITES
MOST LIKELY SEEING JUST LOW CLOUDS. THIS IS IN PART DUE TO THE
DRIER MID LEVELS PER THE 12Z SOUNDING. LOOKING AT VISIBILITIES AND
CEILINGS STAYING IN THE MVFR RANGE. INTERMITTENT REDUCTION IN
VISIBILITIES BETWEEN 3-5SM WILL BE POSSIBLE WITH THE SNOW.
FOR DTW...ONLY MINOR ACCUMULATION POTENTIAL 21-03Z WITH THIS SNOW
GIVEN THE EXPECTED LOWER DURATION/INTENSITY.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILING BELOW 5000 FT THROUGH TUESDAY MORNING.
* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...JVC
LONG TERM....BT
MARINE.......JVC
AVIATION.....SS/JVC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
901 PM CST TUE DEC 25 2012
.UPDATE...
ISSUED AT 838 PM CST TUE DEC 25 2012
00Z NAM IS IN AND IT`S NOT LOOKING TOO GOOD FOR ACCUMULATING SNOW
MUCH NORTH OF OUR CURRENT WARNING. THE GRADIENT WE HAVE IN OUR
SNOWFALL FORECAST STILL LOOKS LIKE IT`S IN JUST ABOUT THE RIGHT
PLACE...BUT AMOUNTS ARE LOOKING A BIT TOO HIGH IF YOU TAKE THE QPF
VERBATIM. SINCE THE NAM IS THE ONLY NEW PIECE OF 00Z GUIDANCE
WE`VE GOT AT THIS TIME (ASIDE FROM THE RUC)...I`M NOT FEELING
PARTICULARLY BRAVE ABOUT CUTTING SNOWFALL AMOUNTS. THIS IS
ESPECIALLY TRUE SINCE THE RUC REALLY RAMPS UP VERTICAL MOTION JUST
SOUTH OF THE STL METRO OVER THE NEXT 2-4 HOURS. THIS MAY BE IN
RESPONSE TO A BACK-BUILDING JET STREAK OVER THE GREAT LAKES. THE
NAM SHOWS THIS TOO...BUT TO A LESSER EXTENT AND THE QPF LOOKS TO
BE MORE DRIVEN BY ISENTROPIC LIFT AND FRONTOGENESIS FURTHER SOUTH
ACROSS SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS. FOR NOW...WILL
LET CURRENT HEADLINES/SNOW AMOUNTS RIDE.
CARNEY
&&
.SHORT TERM...
ISSUED AT 335 PM CST TUE DEC 25 2012
(TONIGHT AND WEDNESDAY)
THE LATEST WATER VAPOR IMAGERY AND WIND PROFILERS/VWPS SHOW THE
UPPER LOW IS NOW LOCATED IN NW TX INVOF OF KTYR. THE STRONGEST
WINDS APPEAR TO BE ENTERING THE BASE OF THE TROF. THIS WOULD
SUGGEST THERE WILL BE CONTINUED EASTWARD MOTION INTO THE EVENING.
THE MODELS ARE REASONABLY WELL CLUSTED WITH THE H5 AND H85 LOW
CENTERS AND SEEM TO BE DOING A GOOD JOB. THE UPPER LOW SHOULD
BOTTOM OUT INVOF OF THE AR/LA BORDER BETWEEN 00-03Z AND THEN TAKE
ITS NEWD TURN EJECTING INTO THE WRN TN VALLEY OVERNIGHT AND INTO
THE OH VALLEY ON WEDNESDAY. DESPITE THE GOOD AGREEMENT IN THE MASS
FIELDS...THERE CONTINUE TO BE VARIANCES IN THE MODEL QPFS...ESPECIALLY
THE NRN EXTENT. THE NEW FORECAST IS BASICALLY A MULTI-MODEL BLEND
ON THE NRN FRINGE INCLUDING THE LATEST RUC.
SNOW IS GRADUALLY SPREADING NWD ACROSS AR ATTM AND WILL BE ENCOUNTERING
RELATIVELY DRIER NELY FLOW. THIS MAY INITIALLY SLOW THE PROGRESSES
BUT AS THE LOW MOVES INTO THE LOWER MS VALLEY THIS EVENING AND
THEN MAKES ITS NEWD TURN...THE LARGE SCALE ASCENT WILL OVERSPREAD
SE MO AND SRN IL MID-LATE EVENING AND SPREAD NEWD INTO SW IL
OVERNIGHT. FOLLOWING GOREE/YOUNKIN TECHNIQUES AND A MORE RECENT
HEAVY SNOW SYNOPTIC CLIMO BY GOSSELIN...THE HEAVIEST SNOW BAND
SHOULD BE SOUTH OF THE CWA ACROSS FAR SE MO AND SRN IL. THE
HEAVIEST SNOW WITHIN THE CWA STILL LOOKS LIKE IT WILL BE ON THE SE
FRINGE...WHERE THERE WILL ROUGHLY BE A PERIOD OF 6-8 HOURS OF
SNOW...MODERATE TO HEAVY AT TIMES. THE HIGHEST AMOUNTS WILL BE
SOUTH OF A LINE FROM CENTERVILLE TO FARMINGTON TO SPARTA TO SALEM
IN THE 5-6 INCH RANGE. I HAVE UPGRADED THE ADVISORY TO A WINTER
STORM WARNING GIVEN THESE SNOWFALL AMOUNTS AND THE STRONG AND
GUSTY NORTH/NORTHWEST WINDS OF 25-35 MPH PRODUCING BLOWING AND
DRIFTING SNOW. AN ADVISORY WILL ROUGHLY SPAN THE NRN FRINGE OF THE
WARNING. ST LOUIS WILL BE IN THE GRADIENT OF MEASURABLE SNOWFALL
AND THE WESTERN SUBURBS MAY SEE LITTLE TO NOTHING...WITH AMOUNTS
OF 1-2 INCHES IN THE SE IL SUBURBS. THE EVENT SHOULD WIND DOWN BY
MID-LATE MORNING ACROSS SW/SC IL. HOPEFULLY THERE WILL BE NO
SURPRISES TONIGHT.
GLASS
&&
.LONG TERM...
ISSUED AT 314 PM CST TUE DEC 25 2012
(THURSDAY THROUGH TUESDAY)
THERE STILL LOOKS TO BE A CHANCE OF SNOW MAINLY FRIDAY NIGHT
ALTHOUGH THE PROBABILITY LOOKS LESS THAN ADVERTISED 2 DAYS AGO.
OVERALL THE PATTERN LOOKS SEASONABLY COLD.
GLASS
&&
.AVIATION...
ISSUED AT 555 PM CST TUE DEC 25 2012
THE LATEST GUIDANCE CONTINUES TO INDICATE THAT THE NWRN EDGE OF
THE SNOW WILL EVENTUALLY SETUP OVER THE STL METRO AREA...AND WILL
FAVOR A MORE PESSIMISTIC TAF FOR KCPS WITH IFR CONDS THAN KSTL
AND KSUS AS A RESULT. WILL KEEP A CLOSE EYE ON HOW THINGS DEVELOP
AS THE EVENING UNFOLDS FOR ANY ADJUSTMENTS NEEDED...NOTABLY WITH
THE MANDATORY 03Z UPDATE. ELSEWHERE TO THE NW OF THE STL METRO
AREA...LOOK FOR PERSISTENT MVFR CIGS THRU THE NIGHT WITH
IMPROVEMENT AFTER SUNRISE. ANOTHER ITEM IS STRONG AND GUSTY N SFC
WNDS DEVELOPING LATER THIS EVENING AS THE STORM CENTER APPROACHES
AND TIGHTENS THE PRES GRAD UP.
SPECIFICS FOR KSTL...AS OF NOW...IT STILL LOOKS LIKE THE NWRN EDGE
OF THE SNOW WILL EDGE THE TAF AREA...BUT NOT ENOUGH CONFIDENCE TO
GO WITH ANYTHING OTHER THAN WHAT THE PREV TAF HAD WHICH WAS A
PROB30 BUFFETED BY FLURRIES. BIGGEST DECISION WAS CROSSWIND
CURRENTLY IN PLACE WITH WIND OUT OF 030...AND TRENDS SHOULD ALL
LEAN TOWARDS THE 020-360 RANGE SO FAVORED THAT ROUTE AFTER THE
FIRST FEW HOURS OF THE VALID PERIOD. OTHERWISE...PERSISTENT MVFR
CIGS ARE IN THE OFFING THRU THE PERIOD...ALTHOUGH MAY SEE SOME
BREAKS EARLY THIS EVENING.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 6 AM CST WEDNESDAY FOR MADISON MO-ST.
FRANCOIS MO-STE. GENEVIEVE MO.
WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR IRON MO-
REYNOLDS MO-WASHINGTON MO.
IL...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST
WEDNESDAY FOR BOND IL-CLINTON IL-FAYETTE IL-MONROE IL-ST.
CLAIR IL.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO NOON CST WEDNESDAY
FOR MARION IL-RANDOLPH IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
932 PM EST TUE DEC 25 2012
.SYNOPSIS...
HIGH PRESSURE MOVES INTO THE NORTH COUNTRY WEDNESDAY. A NOREASTER
WILL IMPACT THE REGION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH
THE FIRST SIGNIFICANT SNOW STORM OF THE YEAR. MAINLY SNOW FOR
NORTHERN NEW YORK AND NORTHERN VERMONT WITH A POSSIBLE WINTRY MIX AT
TIMES FOR SOUTHERN AND EASTERN VERMONT. SNOW AND SNOW SHOWERS WILL
CONTINUE THROUGH FRIDAY MORNING IN THE NORTHERN MOUNTAINS.
&&
.NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/...
AS OF 930 PM EST TUESDAY...GOING FORECAST IN GOOD SHAPE. ONLY
MINOR CHANGES MADE TO ACCOUNT FOR SKY COVER AND TEMPERATURE
TRENDS. RAP 1000-950 MB RELATIVE HUMIDITY FIELDS HANDLING CLOUD
COVER BEST SO FAR THIS EVENING.
PREVIOUS DISCUSSION FROM 641 PM EST FOLLOWS...
WEAK RIDGE OF HIGH PRESSURE WILL BE OVER THE AREA FOR TONIGHT AND
INTO WEDNESDAY MORNING. THIS WILL PROVIDE MOSTLY CLEAR SKIES FOR
MUCH OF THE CHAMPLAIN VALLEY AND CENTRAL AND SOUTHERN VERMONT.
HOWEVER LIGHT NORTHWEST FLOW AND SOME TRAPPED LOW LEVEL MOISTURE
WILL AID IN THE MAINTENANCE AND FURTHER DEVELOPMENT OF SOME LOW
CLOUDS AND EVEN SOME ISOLATED FLURRIES IN THE ADIRONDACKS AND
SAINT LAWRENCE VALLEY OF NEW YORK. SOME LOW CLOUDS AND LIGHT
FLURRIES MAY DEVELOP IN THE NORTHERN CHAMPLAIN VALLEY AND NORTHERN
GREEN MOUNTAINS OVERNIGHT FOR A SHORT TIME AS WELL. THERE IS ALSO
THE POSSIBILITY OF SOME PATCHY FREEZING FOG IN A FEW
LOCATIONS...BUT LEFT OUT OF THE FORECAST FOR NOW. TEMPERATURES
HAVE ALREADY RAPIDLY FALLEN INTO THE TEENS AREA- WIDE. LOW CLOUD
DEVELOPMENT WILL LIMIT HOW FAR THE TEMPERATURES ARE ABLE TO FALL
BUT WIDESPREAD SINGLE DIGITS TO NEAR 10 DEGREES LOOK REASONABLE.
&&
.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 323 PM EST TUESDAY... RIDGE OF HIGH PRESSURE ACROSS QUEBEC
AND ONTARIO NOSING INTO THE NORTH COUNTRY WILL RETREAT SLIGHTLY
DURING WEDNESDAY.
A STRONG CUT-OFF SHORTWAVE LIFTS NE ACROSS OHIO RIVER VALLEY WED
NGT AND OVER NEW ENGLAND ON THU IN A NEG TILT ORIENTATION. SFC LOW
PRESSURE MOVES FROM TENNESSEE VALLEY WED TO ALG OR JUST OFFSHORE OF
NEW JERSEY THU MRNG AND THEN NEAR OR OVER CAPE COD THU. H7 LOW IN
FAVORABLE TRACK FOR MAJOR SNOWFALL ACRS FA BUT SOMEWHAT
MARGINAL/MILDER TEMPERATURES JUST S/E ALG WITH FLOW OFF THE
ATLANTIC TRIES TO INTRODUCE SOME LOW-MID LVL WARMING FOR SRN/ERN
VT.
NWP MODELS ALL IN GOOD AGREEMENT WITH NAM12 THE MILDER MODEL BUT
EVEN WENT COOLER ON THE 12Z RUN. PRIMARILY A HEAVY SNOWFALL EVENT
WITH SOME MIX OR BRIEF CHANGE TO SLEET FOR SRN HALF OF VT AND ERN
VT AS WELL.
STRONG H8 JET (70KTS) MOVING ACRS FA WITH ITS CORE ACRS SRN AND ERN
VT WILL ALLOW FOR SOME SHADOWING AND UPSLOPE EFFECTS WHICH MAY
ACCOUNT FOR WIDE RANGES IN SNOWFALL AMTS. H925 JET OF 40-45 KTS
MAINLY ACRS SRN VT WILL RAISE SOME CONCERNS OF SOME DOWNSLOPING
WINDS BUT THE INVERSION APPEARS JUST ABOVE MOUNTAIN RIDGES.
ATTM...SCNDRY THREAT THAT CAN BE FOCUSED IN LATER FCSTS BUT WIND
GUSTS 35-40 MPH FOR A BRIEF PERIOD POSSIBLE.
AGAIN...TRIED TO INCORPORATE UPSLOPE/DOWNSLOPE CONSIDERATIONS AND A
BLEND OF NAM12/SREF/GFS/ECMWF. SOME OF THE MDLS ARE PERSISTENT WITH
MUCH HEAVIER QPF IN ST LWRNC VLY (1.5-2 INCHES) BUT HAVE ADJUSTED
DOWN. IN THE END...GENERALLY AROUND AN INCH OF QPF WITH THE
FOLLOWING EXCEPTIONS...LOWER (0.6-0.8) IN SRN WESTERN SLOPES AND NE
VT ALONG WITH SOME DOWNSLOPING IN WRN ADRNDKS WHILE HIGHER QPF
(1-1.25) ALONG ERN SLOPES OF SRN GREENS AND SE ADRNDKS.
I/M HANGING ONTO PCPN FOR NRN MTNS THU NGT AND GRADUALLY ENDING FRI
MRNG. THE MAIN ACCUM PRIOR TO 00Z FRI BUT ADDTNL UPSLOPE FOR WRN
SLOPES OF GREENS AND NE VT WHERE WILL HAVE EXPERIENCED ERLR
SHADOWING.
IN THE END...GENERAL 10-15 INCHES WITH SLIGHT LOWER FOR NE VT...ST
LWRNC VLY AND SRN GREENS WITH THE HIGHER AMTS AS MENTIONED ERLR IN
FAVORED SE UPSLOPE REGIONS.
OF NOTE...IT HAS BEEN 658 DAYS SINCE THE LAST 6+" SNOWSTORM AT BTV
(3/7/11) AND THIS WILL LIKELY BREAK THAT STREAK.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 350 PM EST TUESDAY...OVERALL ACTIVE WX PATTERN CONTS WITH
ADDITIONAL CHCS FOR SNOW OVER THE WKND INTO EARLY NEXT WK.
HOWEVER...LATEST TRENDS IN GUIDANCE SHOW LIMITED PHASING FOR
WEEKEND SYSTEM...WHICH WL KEEP BEST DEEP LAYER MOISTURE/LIFT TO
OUR SOUTH AND EAST...ASSOCIATED WITH SFC LOW TRACKING SOUTHEAST OF
THE BENCHMARK. STILL PLENTY OF UNCERTAINTY AS S/W ENERGY EJECTS
FROM WESTERN TROF...AS MODELS TEND TO PERFORM POORLY IN THE
WESTERN MTNS IN THE DAY 4 THRU 6 PERIOD. STILL ANTICIPATING SOME
LIGHT SNOW ASSOCIATED WITH MID/UPPER LVL TROF AND LEFTOVER 850 TO
500MB RH IN TROF AXIS FOR LATE SAT INTO SUN. OTHERWISE...DEEP
CYCLONIC FLW DEVELOPS AS LOW PRES INTENSIFIES ACRS THE CANADIAN
MARITIMES. THIS WL PUSH MUCH COLDER TEMPS ACRS OUR CWA FOR EARLY
NEXT WEEK...ALONG WITH A CHC FOR MAINLY MTN SNOW SHOWERS. BASED ON
EXPECTED FRESH SNOW COVER AND COOL NORTHERLY FLW...WL CUT MACHINE
NUMBERS BY SEVERAL DEGREES THRU THE PERIOD. THINKING MAINLY 20S
FOR THE WEEKEND...BUT HIGHS FALLING BACK INTO THE TEENS AND LOWER
20S NEXT WK...WITH LOWS NEAR NORMAL.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 00Z THURSDAY...RELATIVELY QUIET 24 HOUR TAF PERIOD BEFORE
BIG SNOW STORM HITS THE TAF AREA. OVERNIGHT TONIGHT LOW LEVEL
MOISTURE WILL PRODUCE MVFR TO IFR CLOUD COVER. WILL BE VERY HARD
TO FORECAST AS CLOUD LAYERS MOVE IN AND OUT OF TAF SITES. FOR NOW
WENT WITH LOWER CEILINGS KMSS/KMPV AND KSLK. POSSIBILITY OF MVFR
VIS IN HAZE IN ADIRONDACK SITES AS WELL. CONDITIONS IMPROVE TO
VFR TO VFR CLEAR DURING DAY WEDNESDAY. LIGHT NORTHERLY WIND
THROUGH THE PERIOD.
OUTLOOK 00Z THURSDAY THROUGH SUNDAY...
00Z-12Z THURSDAY CONDITIONS TO QUICKLY DETERIORATE TO IFR/LIFR
FROM SOUTH TO NORTH AS APPROACHING STORM SYSTEM SPREADS SNOW
ACROSS REGION.
12Z THURSDAY-12Z FRIDAY - SIGNIFICANT STORM WL HAVE MAJOR IMPACTS
ON THE AVIATION COMMUNITYWITH LONG DURATIONS OF IFR/LIFR IN
PERIODS OF MODERATE TO HEAVY SNOW AND LOW CIGS. SOME SLEET WL BE
POSSIBLE AT RUT/MPV ON THURSDAY...WITH EASTERLY WIND GUSTS TO 45
MPH POSSIBLE AT RUT. THESE GUSTY WINDS WL CREATE AREAS OF BLOWING
SNOW AND TURBULENCE AT ALL SITES...ESPECIALLY ON THURSDAY
ASSOCIATED WITH A LLVL JET OF 40 TO 60 KNTS.
12Z FRIDAYL-12Z SATURDAY...CONDITIONS SLOWLY IMPROVE ON FRIDAY
WITH VFR CONDITIONS LIKELY BY FRIDAY NIGHT AND SATURDAY.
12Z SATURDAY THROUGH SUNDAY...MVFR CIGS/VIS IN SNOW POSSIBLE
MAINLY IN SOUTH. LOW CONFIDENCE FORECAST IN STORM SYSTEM MOVING
MAINLY TO SOUTH OF AREA...BUT IF TRACK SHIFTS NORTH AREAS MVFR/IFR
WILL ENCOMPASS MORE OF FORECAST AREA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR VTZ001>012-016>019.
NY...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR NYZ026>031-034-035-087.
&&
$$
SYNOPSIS...SLW
NEAR TERM...MUCCILLI
SHORT TERM...SLW
LONG TERM...TABER
AVIATION...HANSON
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
651 PM EST TUE DEC 25 2012
.SYNOPSIS...
HIGH PRESSURE MOVES INTO THE NORTH COUNTRY WEDNESDAY. A NOREASTER
WILL IMPACT THE REGION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH
THE FIRST SIGNIFICANT SNOW STORM OF THE YEAR. MAINLY SNOW FOR
NORTHERN NEW YORK AND NORTHERN VERMONT WITH A POSSIBLE WINTRY MIX AT
TIMES FOR SOUTHERN AND EASTERN VERMONT. SNOW AND SNOW SHOWERS WILL
CONTINUE THROUGH FRIDAY MORNING IN THE NORTHERN MOUNTAINS.
&&
.NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/...
AS OF 641 PM EST TUESDAY...WEAK RIDGE OF HIGH PRESSURE WILL BE
OVER THE AREA FOR TONIGHT AND INTO WEDNESDAY MORNING. THIS WILL
PROVIDE MOSTLY CLEAR SKIES FOR MUCH OF THE CHAMPLAIN VALLEY AND
CENTRAL AND SOUTHERN VERMONT. HOWEVER LIGHT NORTHWEST FLOW AND
SOME TRAPPED LOW LEVEL MOISTURE WILL AID IN THE MAINTENANCE AND
FURTHER DEVELOPMENT OF SOME LOW CLOUDS AND EVEN SOME ISOLATED
FLURRIES IN THE ADIRONDACKS AND SAINT LAWRENCE VALLEY OF NEW YORK.
SOME LOW CLOUDS AND LIGHT FLURRIES MAY DEVELOP IN THE NORTHERN CHAMPLAIN
VALLEY AND NORTHERN GREEN MOUNTAINS OVERNIGHT FOR A SHORT TIME AS
WELL. THERE IS ALSO THE POSSIBILITY OF SOME PATCHY FREEZING FOG IN
A FEW LOCATIONS...BUT LEFT OUT OF THE FORECAST FOR NOW.
TEMPERATURES HAVE ALREADY RAPIDLY FALLEN INTO THE TEENS AREA-WIDE.
LOW CLOUD DEVELOPMENT WILL LIMIT HOW FAR THE TEMPERATURES ARE ABLE
TO FALL BUT WIDESPREAD SINGLE DIGITS TO NEAR 10 DEGREES LOOK
REASONABLE.
&&
.SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 323 PM EST TUESDAY... RIDGE OF HIGH PRESSURE ACROSS QUEBEC
AND ONTARIO NOSING INTO THE NORTH COUNTRY WILL RETREAT SLIGHTLY
DURING WEDNESDAY.
A STRONG CUT-OFF SHORTWAVE LIFTS NE ACROSS OHIO RIVER VALLEY WED
NGT AND OVER NEW ENGLAND ON THU IN A NEG TILT ORIENTATION. SFC LOW
PRESSURE MOVES FROM TENNESSEE VALLEY WED TO ALG OR JUST OFFSHORE OF
NEW JERSEY THU MRNG AND THEN NEAR OR OVER CAPE COD THU. H7 LOW IN
FAVORABLE TRACK FOR MAJOR SNOWFALL ACRS FA BUT SOMEWHAT
MARGINAL/MILDER TEMPERATURES JUST S/E ALG WITH FLOW OFF THE
ATLANTIC TRIES TO INTRODUCE SOME LOW-MID LVL WARMING FOR SRN/ERN
VT.
NWP MODELS ALL IN GOOD AGREEMENT WITH NAM12 THE MILDER MODEL BUT
EVEN WENT COOLER ON THE 12Z RUN. PRIMARILY A HEAVY SNOWFALL EVENT
WITH SOME MIX OR BRIEF CHANGE TO SLEET FOR SRN HALF OF VT AND ERN
VT AS WELL.
STRONG H8 JET (70KTS) MOVING ACRS FA WITH ITS CORE ACRS SRN AND ERN
VT WILL ALLOW FOR SOME SHADOWING AND UPSLOPE EFFECTS WHICH MAY
ACCOUNT FOR WIDE RANGES IN SNOWFALL AMTS. H925 JET OF 40-45 KTS
MAINLY ACRS SRN VT WILL RAISE SOME CONCERNS OF SOME DOWNSLOPING
WINDS BUT THE INVERSION APPEARS JUST ABOVE MOUNTAIN RIDGES.
ATTM...SCNDRY THREAT THAT CAN BE FOCUSED IN LATER FCSTS BUT WIND
GUSTS 35-40 MPH FOR A BRIEF PERIOD POSSIBLE.
AGAIN...TRIED TO INCORPORATE UPSLOPE/DOWNSLOPE CONSIDERATIONS AND A
BLEND OF NAM12/SREF/GFS/ECMWF. SOME OF THE MDLS ARE PERSISTENT WITH
MUCH HEAVIER QPF IN ST LWRNC VLY (1.5-2 INCHES) BUT HAVE ADJUSTED
DOWN. IN THE END...GENERALLY AROUND AN INCH OF QPF WITH THE
FOLLOWING EXCEPTIONS...LOWER (0.6-0.8) IN SRN WESTERN SLOPES AND NE
VT ALONG WITH SOME DOWNSLOPING IN WRN ADRNDKS WHILE HIGHER QPF
(1-1.25) ALONG ERN SLOPES OF SRN GREENS AND SE ADRNDKS.
I/M HANGING ONTO PCPN FOR NRN MTNS THU NGT AND GRADUALLY ENDING FRI
MRNG. THE MAIN ACCUM PRIOR TO 00Z FRI BUT ADDTNL UPSLOPE FOR WRN
SLOPES OF GREENS AND NE VT WHERE WILL HAVE EXPERIENCED ERLR
SHADOWING.
IN THE END...GENERAL 10-15 INCHES WITH SLIGHT LOWER FOR NE VT...ST
LWRNC VLY AND SRN GREENS WITH THE HIGHER AMTS AS MENTIONED ERLR IN
FAVORED SE UPSLOPE REGIONS.
OF NOTE...IT HAS BEEN 658 DAYS SINCE THE LAST 6+" SNOWSTORM AT BTV
(3/7/11) AND THIS WILL LIKELY BREAK THAT STREAK.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 350 PM EST TUESDAY...OVERALL ACTIVE WX PATTERN CONTS WITH
ADDITIONAL CHCS FOR SNOW OVER THE WKND INTO EARLY NEXT WK.
HOWEVER...LATEST TRENDS IN GUIDANCE SHOW LIMITED PHASING FOR
WEEKEND SYSTEM...WHICH WL KEEP BEST DEEP LAYER MOISTURE/LIFT TO
OUR SOUTH AND EAST...ASSOCIATED WITH SFC LOW TRACKING SOUTHEAST OF
THE BENCHMARK. STILL PLENTY OF UNCERTAINTY AS S/W ENERGY EJECTS
FROM WESTERN TROF...AS MODELS TEND TO PERFORM POORLY IN THE
WESTERN MTNS IN THE DAY 4 THRU 6 PERIOD. STILL ANTICIPATING SOME
LIGHT SNOW ASSOCIATED WITH MID/UPPER LVL TROF AND LEFTOVER 850 TO
500MB RH IN TROF AXIS FOR LATE SAT INTO SUN. OTHERWISE...DEEP
CYCLONIC FLW DEVELOPS AS LOW PRES INTENSIFIES ACRS THE CANADIAN
MARITIMES. THIS WL PUSH MUCH COLDER TEMPS ACRS OUR CWA FOR EARLY
NEXT WEEK...ALONG WITH A CHC FOR MAINLY MTN SNOW SHOWERS. BASED ON
EXPECTED FRESH SNOW COVER AND COOL NORTHERLY FLW...WL CUT MACHINE
NUMBERS BY SEVERAL DEGREES THRU THE PERIOD. THINKING MAINLY 20S
FOR THE WEEKEND...BUT HIGHS FALLING BACK INTO THE TEENS AND LOWER
20S NEXT WK...WITH LOWS NEAR NORMAL.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
THROUGH 18Z WEDNESDAY...AVIATION CHALLENGE THRU 18Z WEDS WL
POTENTIAL FOR LOW CLOUDS AND IFR CONDITIONS AT BTV/MPV/SLK/RUT.
SFC ANALYSIS SHOWS LIGHT SNOW FROM THIS MORNING...QUICKLY
DISSIPATING WITH SFC HIGH PRES BUILDING INTO OUR NORTHERN TAF
SITES. THIS HAS RESULTED IN CLRING SKIES AND DRIER AIR TO ADVECT
INTO THE REGION WITH SFC DWPTS IN THE SINGLE DIGITS. QUESTION
TONIGHT WL BE AMOUNT OF LLVL MOISTURE IN MODIFIED ARCTIC AIRMASS
AND POTENTIAL FOR CLOUDS. NAM12 AND RAP SOUNDINGS SHOW LLVL RH
DEVELOPING ACRS BTV/SLK/MPV THIS EVENING...WITH POTENTIAL FOR IFR
CIGS. GIVEN SOME CLOUDS UPSTREAM AND SOUNDINGS SHOWING GOOD RH
BTWN SFC AND 800MB...EXPECT SOME LOW CLOUDS WITH A FEW FLURRIES
POSSIBLE AT MPV/SLK/BTV...WL USE TEMPO GROUP TO COVER MVFR TO
POTENTIALLY IFR CONDITIONS OVERNIGHT...ESPECIALLY AT SLK.
OTHERWISE...MSS/RUT/PBG SHOULD STAY VFR THRU 18Z WEDS.
OUTLOOK 18Z WEDNESDAY THROUGH SATURDAY...
SIGNIFICANT STORM WL HAVE MAJOR IMPACTS ON THE AVIATION COMMUNITY
FROM 06Z THURS THRU 12Z FRIDAY WITH LONG DURATIONS OF IFR/LIFR IN
PERIODS OF MODERATE TO HEAVY SNOW AND LOW CIGS. SOME SLEET WL BE
POSSIBLE AT RUT/MPV ON THURSDAY...WITH EASTERLY WIND GUSTS TO 45
MPH POSSIBLE AT RUT. THESE GUSTY WINDS WL CREATE AREAS OF BLOWING
SNOW AND TURBULENCE AT ALL SITES...ESPECIALLY ON THURSDAY ASSOCIATED
WITH A LLVL JET OF 40 TO 60 KNTS. FLYING CONDITIONS WL SLOWLY
IMPROVE ON FRIDAY AFTN...WITH VFR CONDITIONS LIKELY BY FRIDAY
NIGHT AND SATURDAY.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR VTZ001>012-016>019.
NY...WINTER STORM WARNING FROM 7 PM WEDNESDAY TO 7 AM EST FRIDAY
FOR NYZ026>031-034-035-087.
&&
$$
SYNOPSIS...SLW
NEAR TERM...MUCCILLI
SHORT TERM...SLW
LONG TERM...TABER
AVIATION...TABER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
857 PM CST TUE DEC 25 2012
.DISCUSSION...
LIGHT RADAR ECHOES BECOMING MORE WIDESPREAD ACROSS CENTRAL ND AND
OVER THE FAR WESTERN CWA. GOING FORECAST HAD LOW CHANCE POPS IN
THE FAR WESTERN CWA THIS EVENING AND THEN INCREASING TO AROUND 50
PERCENT AFTER MIDNIGHT...AND THIS CONTINUES TO SEEM REASONABLE.
00Z NAM AND RAP HAVE THE PRECIP OVER THE WESTERN CWA FALLING
APART AS IT MOVES EAST...WITH SOME REFORMING OVER THE VALLEY
DURING THE EARLY MORNING. GIVEN THAT QUITE A FEW OF THESE WEAK
SYSTEMS WILL PRODUCES A FEW TENTHS OF SNOW EVEN IF MODEL OUTPUT IS
NOT IMPRESSIVE WILL LEAVE POPS AS THEY ARE FOR THE REST OF THE
NIGHT. INCLUDED A MENTION OF FLURRIES INTO TOMORROW MORNING AS
THE UPPER SHORTWAVE WILL STILL BE MOVING THROUGH THE AREA AND
THINK THERE COULD STILL BE A FEW FLAKES SQUEEZED OUT.
MORE CHANGES WERE MADE TO THE TEMPERATURES...WHERE READINGS IN THE
EASTERN CWA HAVE DROPPED A BIT FASTER THAN EXPECTED THANKS TO
CLEAR SKIES. HOWEVER...CLOUDS WILL BE INCREASING THROUGHOUT THE
NIGHT AND THERE IS SOME WEAK WARM AIR ADVECTION KICKING IN.
ADJUSTED TEMPS SOMEWHAT TO HAVE SOME AREAS RISING OVERNIGHT.
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH THE NEXT FEW HOURS AS MID AND
HIGH LEVEL CLOUDS INCREASE. SOME LOCATIONS COULD GO DOWN TO MVFR
CONDITIONS DURING THE EARLY MORNING HOURS...PARTICULARLY IN THE
WESTERN FORECAST AREA. CEILINGS DOWN TO 1500-2500 FT AND -SN
DROPPING VIS DOWN TO 2-5SM WILL BE THE PRIMARY IMPACT OF A WEAK
UPPER SYSTEM MOVING THROUGH THE AREA. CONDITIONS SHOULD RETURN TO
VFR TOWARDS THE END OF THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 311 PM CST TUE DEC 25 2012/
SHORT TERM...
THE MAIN FORECAST CHALLENGES REVOLVE AROUND TEMPERATURES
TONIGHT...AND LIGHT SNOW CHANCES TONIGHT AND AGAIN THURS/FRI.
MODELS ARE OVERALL IN GOOD AGREEMENT ON THE LARGE-SCALE FEATURES
THROUGHOUT THIS PERIOD.
AT 19Z...SFC HIGH PRESSURE EXTENDED ACROSS THE NORTHERN PLAINS.
WATER VAPORY IMAGERY SHOWED A SHORTWAVE TROUGH ACROSS EASTERN
MONTANA...WITH SEVERAL SFC OBS SHOWING LIGHT SNOW ACROSS WESTERN
ND IN ADVANCE OF THE SYSTEM. TEMPERATURES HAVE BEEN SLOW TO RISE
GIVEN NEUTRAL TEMPERATURE ADVECTION AND WEAK MIXING UNDER SFC HIGH.
TONIGHT AND WEDNESDAY...CLOUDS WILL CONTINUE TO SPREAD EAST THIS
EVENING AHEAD OF THE ADVANCING WAVE. WEAK ISENTROPIC ON THE 285K
SURFACE AND 700-300 MB Q-VECTOR CONVERGENCE WILL HELP PROVIDE THE
LIFT FOR SOME LIGHT SNOW. THE BEST FORCING IS PROGGED ACROSS THE
SOUTHWEST FORECAST AREA...WHERE SNOW CHANCES ARE BEST. GENERALLY
EXPECT ANY ACCUMULATIONS TO REMAIN MOSTLY UNDER ONE INCH. AS THE
SYSTEM ENCOUNTERS THE DRY SFC HIGH TO THE EAST...EXPECT SOME
DECREASE OF THE LIGHT SNOW FARTHER EAST ACROSS MN. TEMPS WILL BE
TRICKY OVERNIGHT AS CLOUDS INCREASE. THINK THE COOLEST TEMPS WILL
BE ACROSS THE NORTH. WITH THE INCREASE IN CLOUDS...TEMPS LIKELY
LEVEL OFF OR EVEN RISE A FEW DEGREES. WHERE SKIES REMAIN CLEAR
LONGER ACROSS THE EAST...TEMPS MAY INITIALLY FALL FASTER WITH MORE
OPTIMAL RADIATIONAL COOLING CONDITIONS. THE WAVE WILL QUICKLY
PROGRESS INTO CENTRAL MINNESOTA BY EARLY WEDNESDAY...WITH ANY
LINGERING LIGHT SNOW ENDING ACROSS THE EAST. WITH SOME WEAK
850-700 MB WARM AIR ADVECTION...TEMPS SHOULD CLIMB INTO THE SINGLE
DIGITS ABOVE ZERO FOR MOST AREAS.
WEDNESDAY NIGHT...TEMPS ARE NOT EXPECTED TO FALL OFF QUITE AS
MUCH...WITH WEAK LOW-LEVEL WARM AIR ADVECTION CONTINUING. AT THE
SFC...DRY HIGH PRESSURE ACROSS EASTERN MANITOBA WILL STILL BE IN
CONTROL...WITH TEMP TRENDS DEPENDENT ON DEGREE OF CLOUD COVER. AT
THIS POINT...EXPECT LOWS TO BE IN THE SINGLE DIGITS BELOW ZERO TO
NEAR ZERO.
THURSDAY THROUGH FRIDAY...A BROAD LONGWAVE TROUGH WILL LIFT FROM
THE DESERT SOUTHWEST INTO THE CENTRAL PLAINS. MODELS GENERALLY
TAKE THE PRIMARY 500 MB CIRCULATION ACROSS SD/NE...WITH ANOTHER
UPPER WAVE DROPPING SOUTH OUT OF CANADA INTO THE NORTHERN PLAINS BY
LATE FRIDAY. DID MAINTAIN L0W POPS THURSDAY AND FRIDAY...WITH THE
BEST CHANCES ACROSS THE FAR SOUTH. HOWEVER...WITH WEAK FORCING
PROGGED ACROSS THE AREA...EXPECT ANY SNOW TO REMAIN LIGHT. 925 MB
TEMPS CONTINUE TO SLOWLY MODIFY TO -10 TO -15C BY FRIDAY. AS A
RESULT...HIGH TEMPS ON THURSDAY AND FRIDAY WILL REACH CLOSER TO
SEASONAL AVERAGES INTO THE TEENS IN MANY LOCATIONS...WITH LOWS
GENERALLY IN THE SINGLE DIGITS ABOVE AND BELOW ZERO.
LONG TERM (SAT THRU TUE)...
LONGWAVE PATTERN SHIFTS TO A SOMEWHAT FLAT...MID CONTINENTAL OMEGA
BLOCK OVER CENTRAL NOAM FOR THE LATE WEEKEND AND END OF THE CALENDAR
YEAR PERIOD. GFS AND ECMWF AGREE ON WARMING MID LEVEL /H5/ RIDGING
INTO THE WRN DKTAS ON SATURDAY WITHE THE ECMWF CONTINUING WITH A
MODERATE RIDGE INTO MN THROUGH SUNDAY. GFS HAS BECOME FICKLE...
COMPARED TO LAST RUN... AND NOW THREATENS WITH A STRONGER BACKDOOR
COLD FRONT INTO THE NRN PLAINS EARLY ON NEW YEARS EVE DAY. BOTH
MODELS INDICATE PATCHY SNOW FLURRY ACTIVITY EARLY IN THE WEEK... BUT
WITH NO STRONG SIGNAL EVIDENT FCST PACKAGE REMAINS DRY. TEMPS WARM
TO NEAR SEASONAL NORMALS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
134 AM EST MON DEC 24 2012
.SYNOPSIS...
WEAK LOW PRESSURE TRAVELING THROUGH KENTUCKY AND SOUTHEAST OHIO
WILL BRING AN AREA OF PRECIPITATION LATE TONIGHT THROUGH MONDAY.
WEAK HIGH PRESSURE WILL RESULT IN DRY WEATHER ON CHRISTMAS DAY. A
VIGOROUS LOW PRESSURE SYSTEM IS EXPECTED TO DUMP A WINTRY MIX OF
PRECIPITATION OVER THE REGION ON WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LOW PRESSURE OVER NW ARKANSAS WILL MOVE NORTHEAST TO WESTERN
KENTUCKY BY MORNING. LATEST NAM...RAP AND HRRR INDICATE THAT THE
BEST WARM...MOIST ASCENT/ISENTROPIC LIFT WILL OCCUR ALONG AND
SOUTH OF THE OHIO RIVER LATE. THIS MOIST FLOW WILL CAUSE LOW LEVEL
CLOUDS TO INCREASE FROM SOUTH TO NORTH OVERNIGHT WITH CLOUDY SKIES
EXPECTED ALONG AND SOUTH OF THE OHIO RIVER BY MORNING. THERE HAS
BEEN A CONCERN ON HOW FAST PRECIPITATION WILL MOVE INTO OUR AREA
VERSUS SURFACE TEMPERATURES BEING AT OR BELOW FREEZING BY THE TIME
IT ARRIVES. IT NOW APPEARS THAT PRECIPITATION SHOULD PRETTY MUCH
ARRIVE FROM SOUTH TO NORTH AS TEMPERATURES AND DEWPOINTS
RISE...AND NOT MUCH IN THE WAY OF FREEZING RAIN IS EXPECTED. HAVE
SHOWN THIS IN THE LATEST GRIDS AND ZONES WHICH IS TO KEEP A DRY
FORECAST PRETTY MUCH ACRS THE WHITEWATER/MIAMI VALLEYS...WEST
CENTRAL OHIO AND CENTRAL OHIO OVERNIGHT. LOWS WILL OCCUR THIS
EVENING AND EARLY MORNING...THEN THEY SHOULD RISE AS CLOUDS
THICKEN AND THE WIND INCREASES SOME FROM THE EAST AHEAD OF THE
SURFACE LOW.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
WITH THE WEAK LOW MOVING TO EASTERN OHIO...RAIN WILL BE LIKELY
MONDAY IN SOUTHERN AND EASTERN COUNTIES...WITH A GOOD CHANCE OF
RAIN IN THE NORTH AND WEST. THE WINDOW OF OPPORTUNITY FOR FREEZING
PRECIPITATION SEEMS MINIMAL MONDAY MORNING ALONG AND NORTH OF I-70 AS
TEMPERATURES AND DEWPOINTS RISE AS THE PRECIPITATION ARRIVES.
THERE COULD BE A BRIEF PERIOD OF FREEZING RAIN AT THE ONSET BUT IT
SHOULD NOT LAST VERY LONG AND SHOULD HAVE LITTLE IF ANY IMPACT.
A RISE INTO THE 40S IS FORECAST FOR MOST LOCATIONS MONDAY
AFTERNOON.
RAIN WILL BE ENDING MONDAY EVENING WITH THE LOW EXITING TO THE
EAST. A FEW SNOW SHOWERS MAY OCCUR NORTH OF DAYTON BEFORE
PRECIPITATION CHANCES END AROUND MIDNIGHT TUESDAY. AFTER WEAK HIGH
PRESSURE ARRIVES FOR A SHORT STAY...CLOUDS WILL INCREASE AGAIN ON
TUESDAY AHEAD OF THE STRONG LOW. HIGHS AROUND 40 ARE EXPECTED.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
FOCUS IS ON THE WINTER STORM WHICH WILL AFFECT THE REGION AT MID
WEEK. VIGOROUS MID LEVEL S/W TO LIFT FROM THE SRN PLAINS INTO THE
LOWER OH VLY TUESDAY NIGHT AND ACRS THE REGION WEDNESDAY. NUMERICAL
MODEL SOLNS CONTINUE TO SHOW SPREAD REGARDING THE EXACT TRACK OF THE
ASSOCIATED SFC WAVE WHICH LIFTS NE THRU THE REGION ON WEDNESDAY. IN
GENERAL THE GFS DETERMINISTIC SOLNS HAVE BEEN THE FURTHEST WEST AND
THEREFORE BRING MORE WARM AIR INTO ILN/S FA. THE ECMWF SOLN HAS BEEN
MORE CONSISTENT WITH THE LATEST 12Z DETERMINISTIC RUN TRENDING A
LITTLE WEST AND THEREFORE ALLOWING A LTL MORE INTRUSION OF WARM AIR.
GFS ENSEMBLE MEAN SOLN IS PLACED A LTL EAST OF ITS DETERMINISTIC
RUN.
HAVE TRENDED THE LATEST FCST TOWARD THE A SLIGHTLY MODIFIED (WARMER)
SOLN THAN 12Z ECMWF RUN GIVEN TRENDS AND CONSISTENCY.
HAVE SPREAD LKLY POPS IN FROM THE SOUTH TUESDAY NIGHT AND THEN
BUMPED UP POPS TO CATEGORICAL EARLY WEDNESDAY.
USING AT TOP DOWN TECHNIQUE APPLIED TO MODIFIED ECMWF SOLN HAVE FAR
WEST CENTRAL OHIO (NORTHWEST OF DAYTON) STAYING ALL SNOW BUT HAVE A
MIX SPREADING INTO THE REMAINDER OF ILN/S FA AND RAIN SE OF I-71
DURING THE DAY ON WED. AS COLDER AIR WRAPS INTO THE SYSTEM...HAVE
ALL PRECIP CHANGE BACK TO SNOW WEDNESDAY NIGHT. THIS SYSTEM HAS THE
POTENTIAL TO PRODUCE 6 INCHES OR MORE OF SNOW AND SIGNIFICANT ICE.
AT THIS TIME IT LOOKS LIKE A STORM TOTAL 4 TO 6 INCH SNOW BAND IS
PSBL FROM EAST CENTRAL INDIANA THRU FAR W CNTRL OHIO. THERE WILL
LKLY BE A SHARP CUT OFF TO THE SE WITH 1 TO 2 INCHES ALONG AND JUST
WEST OF I-71 AND LESS THAN AN INCH SE OF I-71.
GIVEN THE HIGH DEGREE OF UNCERTAINTY REGARDING THE EXACT TRACK...
WILL CONTINUE TO HIGHLIGHT THIS THREAT IN THE HWO PRODUCT.
AS THIS WINTER STORM LIFTS NE WILL TAPER OFF SNOW EARLY ON THURSDAY.
UPPER LEVEL RIDGING AND SFC RIDGING TO BUILD IN PROVIDING DRY WX
CONDITIONS LATER THURSDAY AND FRIDAY.
MODEL SOLN DIFFERENCES REGARDING THE WEATHER SYSTEM NEXT WEEKEND.
PREV GFS WAS KEEPING PCPN TO OUR SOUTH BUT LATEST RUN BRINGS IN
PRECIP BUT IS WEAKER AND ALLOWS FOR LESS WARM AIR. ECMWF SOLNS HAVE
BEEN STRONGER AND ALLOW FOR MORE INITIAL WARM AIR INTRUSION. HAVE
SPREAD CHC POPS IN FRIDAY NIGHT AND THEN CONT HIGH CHC POPS ON
SATURDAY. HAVE ALLOWED FOR A MIX OF RAIN AND SNOW OVER THE SE HALF
AND KEPT ALL SNOW NW. SOME LINGERING SNOW SHOWERS WILL BE PSBL ON
SUNDAY WITH THE BEST CHC ACRS THE NORTH.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
ANY RAIN THAT BEGINS TOWARDS DAYBREAK TODAY WILL FALL WHERE
TEMPERATURES ARE ABOVE FREEZING AND ICY CONDITIONS ARE NOT
EXPECTED TO OCCUR AT THIS MOMENT IN TIME. LOW CIGS WILL SLIDE INTO
THE CINCY METRO AREA JUST BEFORE DAYBREAK AND RAIN WILL FOLLOW
SHORTLY AFTER. SLIGHTLY LATER TIMING IS EXPECTED AT KDAY/KILN AND
BY LATE MORNING IN COLUMBUS METRO AREA.
SHOWERS SHOULD TAPER OFF IN THE EARLY AFTERNOON...LATE MORNING
FURTHER SOUTHWEST...BUT CLOUD COVER WILL REMAIN IN THE 1-2KFT
RANGE. NORTHWEST WINDS AND LOW CLOUD COVER WILL PERSIST OVERNIGHT.
OUTLOOK...IFR CEILINGS AND VISIBILITIES ARE POSSIBLE
WEDNESDAY...LIFTING TO MVFR THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...CONIGLIO/HICKMAN
NEAR TERM...CONIGLIO/HICKMAN
SHORT TERM...CONIGLIO
LONG TERM...AR
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
649 AM EST MON DEC 24 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL TRACK NORTHEAST UP THE OHIO RIVER VALLEY
TODAY...CROSSING THE REGION LATE TONIGHT. THIS WEATHER FEATURE WILL
BRING MOST AREAS OF CENTRAL PENNSYLVANIA JUST ENOUGH SNOW FOR A
WHITE CHRISTMAS. A RIDGE OF HIGH PRESSURE WILL FOLLOW FOR CHRISTMAS
DAY...WITH PLENTY OF CLOUDS AND LIGHT NORTHERLY WINDS. A MORE
SIGNIFICANT AND WIDESPREAD WINTER STORM WILL TAKE AIM ON THE ENTIRE
NORTHEAST U.S. FOR WEDNESDAY AND THURSDAY. THE POTENTIAL EXISTS FOR
HEAVY SNOWFALL ACROSS THE NORTHWEST HALF OF PENNSYLVANIA...WITH A
GRADUAL INCREASE IN MIXED PRECIPITATION HEADING SOUTHEAST TOWARD THE
LOWER SUSQUEHANNA VALLEY. BLUSTERY AND COLD CONDITIONS WITH
FLURRIES...AND MOUNTAIN SNOW SHOWERS WILL FOLLOW FOR THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
A SHALLOW WEDGE OF COLDER AIR HAS ADVECTED SOUTH TO COVER MUCH OF
THE REGION EARLY TODAY. SLIGHTLY MILDER/ABOVE FREEZING AIR AT 850 MB
WAS ADVANCING EAST ACROSS THE GREATER PITTSBURGH AREA ATTM...JUST
ABOVE THE NEARLY STALLED OUT...EAST TO WEST 925 MB FRONT. HIGH RES
NAM AND RUC MODELS SHOW THAT A BKN-OVC STRATO CU LAYER AROUND 2-3KFT
AGL WILL PERSIST THE NEXT FEW HOURS ACROSS THE NRN TIER COUNTIES...
BEFORE ERODING AROUND SUNRISE. HIGH CLOUDS WILL STREAM IN FROM THE
WSW AND THICKEN UP LATER THIS MORNING.
TEMPS AT DAYBREAK WILL BE COLDEST ACROSS THE SOUTHERN HALF OF THE
STATE /MAINLY IN THE LOWER 20S/...WHILE THE CLOUD BLANKET ACROSS THE
NORTH RESULTS IN SLIGHTLY WARMER MINS IN THE MID 20S.
00Z MODEL SUITE AND LATEST ENSEMBLE GUIDANCE SHOWS A HIGH
PROBABILITY FOR A LIGHT SNOWFALL OF AN INCH OR TWO ACROSS THE REGION
THIS AFTERNOON INTO TONIGHT AS A WEAK AREA OF LOW PRESSURE MOVES ENE
UP THE OHIO RIVER VALLEY. HIGH RES MODEL THERMAL/WET BULB THERMAL
PROFILES WITHIN 2 KFT AGL INDICATE THAT MUCH OF THE LIGHT PRECIP
WILL FALL IN THE FORM OF SNOW. THE LOWEST 1 KFT AGL MAY WARM BRIEFLY
INTO THE MID AND UPPER 30S ACROSS THE SOUTHEAST VALLEYS TO CAUSE THE
LIGHT SNOW TO MIX WITH LIGHT RAIN.
OTHERWISE...925-850 MB WET-BULB TEMPS WILL BE A FEW TO SVRL DEG C
BELOW ZERO FOR THE DURATION OF THIS EVENT...SUPPORT PRIMARILY SNOW.
THE ONLY LOCATION AT THIS POINT THAT WILL SEE A LAYER OF SLIGHTLY
ABOVE FREEZING AIR ALOFT WILL BE PORTIONS OF THE LAUREL HIGHLANDS.
THERE...SOME LIGHT FREEZING RAIN AND SLEET SHOULD MIX IN AT
TIMES...PERHAPS LEADING TO TREACHEROUS HOLIDAY TRAVEL. A WINTER
WEATHER ADVISORY WAS POSTED FOR SOMERSET COUNTY FROM 17Z TODAY
THROUGH 06Z CHRISTMAS.
SFC TEMPS THIS AFTERNOON IN THE LOWER TO MID 30S ACROSS MUCH OF THE
REMAINDER OF CENTRAL PENN SHOULD ALLOW TREATED/PRIMARY ROADS TO STAY
MAINLY WET AS SNOWFALL RATES SHOULD BE QUITE LIGHT...PERHAPS AROUND
0.25 INCH PER HOUR.
AFTER THE MAIN WAVE OF PRECIP COMES THROUGH EARLY THIS EVENING...
VERY WEAK FORCING AND SPOTTY LIGHT PRECIP WILL CONTINUE
OVERNIGHT...AND LLVL WINDS GO WESTERLY. THIS WILL PROLONG THE
NEAR-FREEZING TEMPS AND POSSIBILITY FOR -FZDZ ACROSS THE AREA...ESP
THE WRN MTS. ALL OF THE HIGH/COLD CLOUDS GO AWAY IMMEDIATELY AFTER
THE MAIN PUSH...SO GOOD SEEDING OF ICE CRYSTALS IS GONE AND MUCH OF
THE AREA COULD SEE PATCHY FZDZ. AGAIN...ALL TOO FAR AWAY AND MINOR
PRECIP AMOUNTS TO MAKE A CALL ON THIS YET.
TEMPS GREETING SANTA AND HIS REINDEER TEAM EARLY CHRISTMAS MORNING
WILL VARY FROM THE L20S UP NORTH...TO THE MID AND UPPER 20S ACROSS
CENTRAL AND SOUTHERN PENN.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
A WEAK RIDGE OF HIGH PRESSURE DRIFTING EAST ACROSS THE STATE WILL
PROVIDE A RATHER SHORT WINDOW OF ONLY 24-30 HOURS WITH IMPROVED
TRAVEL CONDITIONS FROM LATER CHRISTMAS MORNING INTO EARLY WEDNESDAY.
MAX TEMPS CHRISTMAS AFTERNOON WILL BE AROUND 30F ACROSS THE NW
MTNS...AND MID 30S TO LOWER 40S ELSEWHERE.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A SIGNIFICANT WINTER STORM WILL BEGIN TO STRENGTHEN ACROSS THE LOWER
MISS AND TENN VALLEYS CHRISTMAS NIGHT AND HEAD NORTHEAST...SPREADING
THE LEADING EDGE OF A LARGE SHIELD OF PRECIPITATION OVER THE SWRN
PART OF REGION DURING THE MIDDAY HOURS WEDNESDAY...AND BEGINNING
DURING THE LATE AFTERNOON AND EARLY EVENING HOURS ELSEWHERE.
PRECIP TYPE SHOULD BE SNOW FOR AT LEAST A FEW TO SVRL HOURS IN ALL
LOCATIONS /AS 925-850 MB WET BULB TEMPS EVEN IN THE SE WILL BE -2 TO
-4C AND NOTABLY COLDER FURTHER TO THE NORTH/ THANKS TO INCREASINGLY
STRONG LLVL NORTHERLY AGEOS FLOW.
23/21Z THROUGH 24/06Z OPERATIONAL U.S. AND EURO MODEL RUNS /AND
THEIR RESPECTIVE ENSEMBLES/ ARE COMING INTO PRETTY GOOD AGREEMENT
TRACKING A DYING PRIMARY LOW NE ACROSS THE OHIO VALLEY WITH A
SECONDARY LOW RAPIDLY INTENSIFYING JUST INLAND FROM THE DELMARVA
PENINSULA LATE WEDNESDAY NIGHT.
WILL MAKE JUST SOME MINOR MODIFICATIONS TO THE PRECIP TYPE AND
AMOUNT ACROSS THE CWA FOR WEDNESDAY INTO THURSDAY.
THIS APPARENT/POTENT MILLER-B TYPE EVENT WILL EVOLVE AS THE TRANSFER
OF ENERGY TO THE DELMARVA COAST OCCURS WEDNESDAY NIGHT AT THE NOSE
OF A STRONG UPPER LEVEL JET /THAT WILL BE ROUNDING THE BASE OF THE
AMPLIFYING AND SLIGHTLY NEGATIVE TILT UPPER TROUGH/ AIMED AT THE
VA/MID ATLANTIC COAST.
WILL KEEP LAYER-CAKE PRECIP TYPES PAINTED FROM NW TO SE FOR THE
WEDNESDAY AFTERNOON/NIGHT PERIOD AS THE LATEST 06Z NAM STILL
INDICATES THAT A RATHER SHALLOW LAYER OF NEAR TO SLIGHTLY ABOVE
FREEZING AIR SURGE NWD INTO AT LEAST CENTRAL AND SRN PENN IN THE
800-750 MB LAYER AS THE ENERGY BEGINS TO TRANSFER ACROSS THE CENTRAL
APPALACHIANS.
HOWEVER...STRONG UVVEL AND DYNAMIC COOLING IN THE INCREASINGLY
DIVERGENT UPPER FLOW COULD KEEP THE PRECIP MAINLY MDT TO HVY SNOW
ACROSS THE REGION NORTH OF KAOO...KUNV AND KBGM FOR THE BULK OF THE
STORM.
QUITE A BIT OF UNCERTAINTY CONTINUES TO EXIST ON THIS KEY FEATURE
WHICH IS THE EXTENT AND DEPTH OF THE WARMER AIR INTRUSION AND ITS
ULTIMATE EFFECTS ON CENTRAL/EASTERN PORTIONS OF CWA.
THE BEST FORECAST REMAINS A LIKELY MODERATE TO HEAVY SNOWFALL ACROSS
THE NRN AND WESTERN MTNS...WITH MODERATE AMOUNTS OF SNOW/SLEET
IMPACT THE SUSQ VALLEY AND PORTIONS OF THE SCENT MTNS.
AS A RESULT OF THE HIGHLY ANOMALOUS...APPROX PLUS 4 SIGMA SERLY 850
MB JET AND 1-2 SIGMA PWATS ACCOMPANYING THIS STORM...LIQUID
EQUIVALENT QPF FOR THIS EVENT LOOKS TO BE 1-1.25 INCHES ACROSS MUCH
OF THE FCST AREA...WITH AROUND 1.5 INCHES OVER THE SOUTH AND EAST.
24/03Z SREF SHOWS A 30-50 PROBABILITY FOR STORM TOTAL PRECIP OF 2
INCHES IN OUR FAR SERN ZONES.
STORM TOTAL SNOWFALL HAS THE POTENTIAL TO BE IN THE 6-10 INCH RANGE
ACROSS THE NW/NCENT MTNS AND LAURELS...SEVERAL INCHES OF SNOW AND
SIGNIFICANT SLEET THROUGHOUT THE CENTRAL ZONES...AND A GENERAL MIXED
BAG MESS ACROSS THE LOWER SUSQ REGION...AFTER AN INITIAL PERIOD OF
SNOW. THIS CONCURS WITH HPC/S LATEST WINTER WEATHER GRAPHICS.
COLD AND BLUSTERY NORTHWEST FLOW REGIME DEVELOPS BEHIND THE
DEPARTING STORM THU AND FRI WITH CENTRAL AND SERN PENN FLURRIES AND
SCTD SNOW SHOWERS...WITH UPSLOPE SNOW AND LES IMPACTING THE LAURELS
AND NW MTNS.
ANOTHER WEAKER STORM PROGGED FOR NEXT WEEKEND LOOKS COLD ENOUGH
FOR A GENERALLY LIGHT SNOW EVENT SAT INTO SUN.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
LOW LVL MOISTURE TRAPPED BENEATH INVERSION IS CREATING MVFR STRATOCU
ACROSS THE N MTNS EARLY THIS MORNING. HOWEVER...MDLS INDICATE THIS
INVERSION AND RESULTING STRATOCU WILL BREAK UP BY LATE AM.
A LOW PRES SYSTEM RIDING UP THE OHIO VALLEY WILL SPREAD LOWERING
CLOUDS AND LGT SNOW ACROSS THE REGION THIS AFTN AND EVENING.
LATEST MDL DATA SUGGESTS A RAPID DETERIORATION IN VSBYS AS SNOW
ARRIVES ACROSS THE SOUTHERN PA AIRFIELDS BTWN 19Z-22Z...THEN
SPREADS NORTHEAST ACROSS THE REST OF CENTRAL PA BY 00Z. A 4-6 HOUR
PERIOD OF SNOW WITH VSBYS BTWN 1-3SM APPEARS LIKELY AT MOST
LOCATIONS. EVEN AFTER PRECIP WINDS DOWN LATE THIS EVENING...RESIDUAL
MOISTURE AND LGT WINDS SHOULD RESULT IN LINGERING FOG/LOW CIGS
ACROSS THE REGION.
AS LOW DEPARTS THE AREA LATE TONIGHT...EXPECT A WESTERLY BREEZE TO
DEVELOP...RESULTING IN IMPROVING CIGS/VSBYS EAST OF THE MTNS...BUT
CONTINUED LOW CIGS WHERE THE FLOW ASCENDS THE ALLEGHENIES AT BFD
AND JST.
OUTLOOK...
TUE...AM LOW CIGS POSS W MTNS.
WED...WINTRY MIX WITH LOW CIGS/VSBYS POSSIBLE.
THU...WINDY WITH WINTRY MIX/LOW CIGS POSS EARLY. PM SHSN POSS W MTNS.
FRI...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM NOON TODAY TO 1 AM EST TUESDAY
FOR PAZ033.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/RXR
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
440 AM EST MON DEC 24 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL TRACK NORTHEAST UP THE OHIO RIVER VALLEY
TODAY...CROSSING THE REGION LATE TONIGHT. THIS WEATHER FEATURE WILL
BRING MOST AREAS OF CENTRAL PENNSYLVANIA JUST ENOUGH SNOW FOR A
WHITE CHRISTMAS. A RIDGE OF HIGH PRESSURE WILL FOLLOW FOR CHRISTMAS
DAY...WITH PLENTY OF CLOUDS AND LIGHT NORTHERLY WINDS. A MORE
SIGNIFICANT AND WIDESPREAD WINTER STORM WILL TAKE AIM ON THE ENTIRE
NORTHEAST U.S. FOR WEDNESDAY AND THURSDAY. THE POTENTIAL EXISTS FOR
HEAVY SNOWFALL ACROSS THE NORTHWEST HALF OF PENNSYLVANIA...WITH A
GRADUAL INCREASE IN MIXED PRECIPITATION HEADING SOUTHEAST TOWARD THE
LOWER SUSQUEHANNA VALLEY. BLUSTERY AND COLD CONDITIONS WITH
FLURRIES...AND MOUNTAIN SNOW SHOWERS WILL FOLLOW FOR THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
A SHALLOW WEDGE OF COLDER AIR HAS ADVECTED SOUTH TO COVER MUCH OF
THE REGION EARLY TODAY. SLIGHTLY MILDER/ABOVE FREEZING AIR AT 850 MB
WAS ADVANCING EAST ACROSS THE GREATER PITTSBURGH AREA ATTM...JUST
ABOVE THE NEARLY STALLED OUT...EAST TO WEST 925 MB FRONT. HIGH RES
NAM AND RUC MODELS SHOW THAT A BKN-OVC STRATO CU LAYER AROUND 2-3KFT
AGL WILL PERSIST THE NEXT FEW HOURS ACROSS THE NRN TIER COUNTIES...
BEFORE ERODING AROUND SUNRISE. HIGH CLOUDS WILL STREAM IN FROM THE
WSW AND THICKEN UP LATER THIS MORNING.
TEMPS AT DAYBREAK WILL BE COLDEST ACROSS THE SOUTHERN HALF OF THE
STATE /MAINLY IN THE LOWER 20S/...WHILE THE CLOUD BLANKET ACROSS THE
NORTH RESULTS IN SLIGHTLY WARMER MINS IN THE MID 20S.
00Z MODEL SUITE AND LATEST ENSEMBLE GUIDANCE SHOWS A HIGH
PROBABILITY FOR A LIGHT SNOWFALL OF AN INCH OR TWO ACROSS THE REGION
THIS AFTERNOON INTO TONIGHT AS A WEAK AREA OF LOW PRESSURE MOVES ENE
UP THE OHIO RIVER VALLEY. HIGH RES MODEL THERMAL/WET BULB THERMAL
PROFILES WITHIN 2 KFT AGL INDICATE THAT MUCH OF THE LIGHT PRECIP
WILL FALL IN THE FORM OF SNOW. THE LOWEST 1 KFT AGL MAY WARM BRIEFLY
INTO THE MID AND UPPER 30S ACROSS THE SOUTHEAST VALLEYS TO CAUSE THE
LIGHT SNOW TO MIX WITH LIGHT RAIN.
OTHERWISE...925-850 MB WET-BULB TEMPS WILL BE A FEW TO SVRL DEG C
BELOW ZERO FOR THE DURATION OF THIS EVENT...SUPPORT PRIMARILY SNOW.
THE ONLY LOCATION AT THIS POINT THAT WILL SEE A LAYER OF SLIGHTLY
ABOVE FREEZING AIR ALOFT WILL BE PORTIONS OF THE LAUREL HIGHLANDS.
THERE...SOME LIGHT FREEZING RAIN AND SLEET SHOULD MIX IN AT
TIMES...PERHAPS LEADING TO TREACHEROUS HOLIDAY TRAVEL. A WINTER
WEATHER ADVISORY WAS POSTED FOR SOMERSET COUNTY FROM 17Z TODAY
THROUGH 06Z CHRISTMAS.
SFC TEMPS THIS AFTERNOON IN THE LOWER TO MID 30S ACROSS MUCH OF THE
REMAINDER OF CENTRAL PENN SHOULD ALLOW TREATED/PRIMARY ROADS TO STAY
MAINLY WET AS SNOWFALL RATES SHOULD BE QUITE LIGHT...PERHAPS AROUND
0.25 INCH PER HOUR.
AFTER THE MAIN WAVE OF PRECIP COMES THROUGH EARLY THIS EVENING...
VERY WEAK FORCING AND SPOTTY LIGHT PRECIP WILL CONTINUE
OVERNIGHT...AND LLVL WINDS GO WESTERLY. THIS WILL PROLONG THE
NEAR-FREEZING TEMPS AND POSSIBILITY FOR -FZDZ ACROSS THE AREA...ESP
THE WRN MTS. ALL OF THE HIGH/COLD CLOUDS GO AWAY IMMEDIATELY AFTER
THE MAIN PUSH...SO GOOD SEEDING OF ICE CRYSTALS IS GONE AND MUCH OF
THE AREA COULD SEE PATCHY FZDZ. AGAIN...ALL TOO FAR AWAY AND MINOR
PRECIP AMOUNTS TO MAKE A CALL ON THIS YET.
TEMPS GREETING SANTA AND HIS REINDEER TEAM EARLY CHRISTMAS MORNING
WILL VARY FROM THE L20S UP NORTH...TO THE MID AND UPPER 20S ACROSS
CENTRAL AND SOUTHERN PENN.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
A WEAK RIDGE OF HIGH PRESSURE DRIFTING EAST ACROSS THE STATE WILL
PROVIDE A RATHER SHORT WINDOW OF ONLY 24-30 HOURS WITH IMPROVED
TRAVEL CONDITIONS FROM LATER CHRISTMAS MORNING INTO EARLY WEDNESDAY.
MAX TEMPS CHRISTMAS AFTERNOON WILL BE AROUND 30F ACROSS THE NW
MTNS...AND MID 30S TO LOWER 40S ELSEWHERE.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A SIGNIFICANT WINTER STORM WILL BEGIN TO STRENGTHEN ACROSS THE LOWER
MISS AND TENN VALLEYS CHRISTMAS NIGHT AND HEAD NORTHEAST...SPREADING
THE LEADING EDGE OF A LARGE SHIELD OF PRECIPITATION OVER THE SWRN
PART OF REGION DURING THE MIDDAY HOURS WEDNESDAY...AND BEGINNING
DURING THE LATE AFTERNOON AND EARLY EVENING HOURS ELSEWHERE.
PRECIP TYPE SHOULD BE SNOW FOR AT LEAST A FEW TO SVRL HOURS IN ALL
LOCATIONS /AS 925-850 MB WET BULB TEMPS EVEN IN THE SE WILL BE -2 TO
-4C AND NOTABLY COLDER FURTHER TO THE NORTH/ THANKS TO INCREASINGLY
STRONG LLVL NORTHERLY AGEOS FLOW.
23/21Z THROUGH 24/06Z OPERATIONAL U.S. AND EURO MODEL RUNS /AND
THEIR RESPECTIVE ENSEMBLES/ ARE COMING INTO PRETTY GOOD AGREEMENT
TRACKING A DYING PRIMARY LOW NE ACROSS THE OHIO VALLEY WITH A
SECONDARY LOW RAPIDLY INTENSIFYING JUST INLAND FROM THE DELMARVA
PENINSULA LATE WEDNESDAY NIGHT.
WILL MAKE JUST SOME MINOR MODIFICATIONS TO THE PRECIP TYPE AND
AMOUNT ACROSS THE CWA FOR WEDNESDAY INTO THURSDAY.
THIS APPARENT/POTENT MILLER-B TYPE EVENT WILL EVOLVE AS THE TRANSFER
OF ENERGY TO THE DELMARVA COAST OCCURS WEDNESDAY NIGHT AT THE NOSE
OF A STRONG UPPER LEVEL JET /THAT WILL BE ROUNDING THE BASE OF THE
AMPLIFYING AND SLIGHTLY NEGATIVE TILT UPPER TROUGH/ AIMED AT THE
VA/MID ATLANTIC COAST.
WILL KEEP LAYER-CAKE PRECIP TYPES PAINTED FROM NW TO SE FOR THE
WEDNESDAY AFTERNOON/NIGHT PERIOD AS THE LATEST 06Z NAM STILL
INDICATES THAT A RATHER SHALLOW LAYER OF NEAR TO SLIGHTLY ABOVE
FREEZING AIR SURGE NWD INTO AT LEAST CENTRAL AND SRN PENN IN THE
800-750 MB LAYER AS THE ENERGY BEGINS TO TRANSFER ACROSS THE CENTRAL
APPALACHIANS.
HOWEVER...STRONG UVVEL AND DYNAMIC COOLING IN THE INCREASINGLY
DIVERGENT UPPER FLOW COULD KEEP THE PRECIP MAINLY MDT TO HVY SNOW
ACROSS THE REGION NORTH OF KAOO...KUNV AND KBGM FOR THE BULK OF THE
STORM.
QUITE A BIT OF UNCERTAINTY CONTINUES TO EXIST ON THIS KEY FEATURE
WHICH IS THE EXTENT AND DEPTH OF THE WARMER AIR INTRUSION AND ITS
ULTIMATE EFFECTS ON CENTRAL/EASTERN PORTIONS OF CWA.
THE BEST FORECAST REMAINS A LIKELY MODERATE TO HEAVY SNOWFALL ACROSS
THE NRN AND WESTERN MTNS...WITH MODERATE AMOUNTS OF SNOW/SLEET
IMPACT THE SUSQ VALLEY AND PORTIONS OF THE SCENT MTNS.
AS A RESULT OF THE HIGHLY ANOMALOUS...APPROX PLUS 4 SIGMA SERLY 850
MB JET AND 1-2 SIGMA PWATS ACCOMPANYING THIS STORM...LIQUID
EQUIVALENT QPF FOR THIS EVENT LOOKS TO BE 1-1.25 INCHES ACROSS MUCH
OF THE FCST AREA...WITH AROUND 1.5 INCHES OVER THE SOUTH AND EAST.
24/03Z SREF SHOWS A 30-50 PROBABILITY FOR STORM TOTAL PRECIP OF 2
INCHES IN OUR FAR SERN ZONES.
STORM TOTAL SNOWFALL HAS THE POTENTIAL TO BE IN THE 6-10 INCH RANGE
ACROSS THE NW/NCENT MTNS AND LAURELS...SEVERAL INCHES OF SNOW AND
SIGNIFICANT SLEET THROUGHOUT THE CENTRAL ZONES...AND A GENERAL MIXED
BAG MESS ACROSS THE LOWER SUSQ REGION...AFTER AN INITIAL PERIOD OF
SNOW. THIS CONCURS WITH HPC/S LATEST WINTER WEATHER GRAPHICS.
COLD AND BLUSTERY NORTHWEST FLOW REGIME DEVELOPS BEHIND THE
DEPARTING STORM THU AND FRI WITH CENTRAL AND SERN PENN FLURRIES AND
SCTD SNOW SHOWERS...WITH UPSLOPE SNOW AND LES IMPACTING THE LAURELS
AND NW MTNS.
ANOTHER WEAKER STORM PROGGED FOR NEXT WEEKEND LOOKS COLD ENOUGH
FOR A GENERALLY LIGHT SNOW EVENT SAT INTO SUN.
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
LOW LVL MOISTURE TRAPPED BENEATH INVERSION WILL CREATE MVFR STRATOCU
ACROSS THE N MTNS EARLY THIS MORNING. ACROSS SOUTHERN PA...MCLEAR
SKIES AND A NEARLY CALM WIND COULD CREATE SOME VALLEY FOG ACROSS THE
LAUREL HIGHLANDS. HOWEVER...JST/S RIDGETOP LOCATION SHOULD PRECLUDE
FOG AT THE AIRPORT.
A LOW PRES SYSTEM RIDING UP THE OHIO VALLEY WILL SPREAD LOWERING
CLOUDS AND LGT SNOW ACROSS THE REGION THIS AFTN AND EVENING.
LATEST MDL DATA SUGGESTS A RAPID DETERIORATION IN VSBYS AS SNOW
ARRIVES ARND 18Z AT JST...THEN SPREADS NORTHEAST ACROSS THE REST
OF CENTRAL PA BY 00Z. A 4 TO 6 HR PERIOD OF SNOW WITH VSBYS BTWN
1-2SM APPEARS LIKELY AT MOST LOCATIONS. EVEN AFTER PRECIP WINDS
DOWN LATE THIS EVENING...RESIDUAL MOISTURE AND LGT WINDS SHOULD
RESULT IN LINGERING FOG/LOW CIGS ACROSS THE REGION.
OUTLOOK...
TUE...AM LOW CIGS POSS W MTNS.
WED...WINTRY MIX WITH LOW CIGS/VSBYS POSSIBLE.
THU...WINDY WITH WINTRY MIX/LOW CIGS POSS EARLY. PM SHSN POSS W MTNS.
FRI...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM NOON TODAY TO 1 AM EST TUESDAY
FOR PAZ033.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT/RXR
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1208 PM CST MON DEC 24 2012
.UPDATE...FOR 18Z AVIATION FORECAST
&&
.AVIATION...
SURFACE LOW HAS MOVED NORTHEAST INTO SOUTHWEST OHIO WITH COLD
FRONT DOWN ALONG THE PLATEAU INTO NORTH ALABAMA AT 18Z. MID LEVEL
TROUGH HAS SHIFTED EAST WITH AXIS ALONG THE PLATEAU. NORMALLY WE
WOULD EXPECT CLEARING TO FOLLOW BUT NOT TODAY AS WINDS NEAR THE
SURFACE AND LOWER LEVELS OF THE TROPOSPHERE ARE VERY LIGHT ALONG
WITH A SURFACE INVESION KEEPING LOW CLOUDS LOCKED IN ACROSS
MIDDLE TENNESSEE AND ADJACENT AREAS. HOWEVER...WE ARE BEGINNING TO SEE
MORE BREAKS IN THE OVERCAST IN WESTERN MIDDLE TENNESSEE. LOW
CEILINGS WILL LIKELY REMAIN ACROSS THE AREA FOR MOST OF THE
DAYLIGHT HOURS WITH SOME IMPROVEMENT POSSIBLE AT LEAST TEMPORARILY
DURING THE EVENING. GENERALLY FOGGY CONDITIONS WILL REMAIN ALONG
THE PLATEAU PRETTY MUCH FOR THE NEXT 24 HOURS WITH IFR AND LIFR
CONDITIONS AT CROSSVILLE ALTHOUGH THERE COULD BE BRIEF TEMPORARILY
IMPROVEMENTS.
BOYD
&&
.PREV DISCUSSION... /ISSUED 929 AM CST MON DEC 24 2012/
UPDATE...FOR AVIATION FORECAST AT 15Z
EVEN THOUGH SURFACE LOW AND MID LEVEL SHORT WAVE ARE MOVING
THROUGH MIDDLE TENNESSEE AT 15Z SOME DRYING WILL TAKE PLACE IN THE
MID LEVELS WHILE MOISTURE IS EXPECTED TO REMAIN IN THE LOWER LEVELS.
FORECAST SOUNDINGS OFF THE LATEST RUC RUN KEEP LOW LEVEL MOISTURE
ACROSS THE MID STATE WHILE DRYING OUT MID LEVELS THROUGH A GOOD
PART OF THE DAY KEEPING MVFR AND OCCASIONAL IFR CONDTIONS AT BOTH
CLARKSVILLE AND NASHVILLE AND BASICALLY IFR CONDITIONS AT
CROSSVILLE LIKELY THROUGH THE DAYLIGHT HOURS. SATELLITE DOES SHOW
OCCASIONAL BREAKS IN THE OVERCAST (BINOVC) BUT THEY FILL IN RATHER
QUICKLY. LOW CLOUDS EXTEND ALL THE WAY BACK TO THE MISSISSIPPI
RIVER AT THIS TIME.
BOYD
AVIATION...
PREV DISCUSSION... /ISSUED 525 AM CST MON DEC 24 2012/
UPDATE...ADDED AVIATION SECTION FOR 12Z TAF`S.
AVIATION...BNA/CKV/CSV...COLD FRONT MOVING ACROSS MIDDLE
TENNESSEE THIS MORNING, BRINGING LIGHT TO MODERATE RAINFALL,
FOG, AND LOW CIGS. EXPECT IFR CONDITIONS FOR MUCH OF THE MORNING,
WITH CIGS IMPROVING DURING THE AFTERNOON AND EVENING AT BNA AND
CKV, AND REMAINING VFR OVERNIGHT. CSV WILL LIKELY EXPERIENCE LOW
CIGS THROUGHOUT THE DAY, WITH POSSIBLE LIFR CONDITIONS DEVELOPING
OVERNIGHT AS VV`S DROP TO NEAR ZERO AND VSBY AS LOW AS 1/2 MILE.
PREV DISCUSSION... /ISSUED 401 AM CST MON DEC 24 2012/
DISCUSSION...LOW PRESSURE SYSTEM CENTERED OVER THE MID MS VALLEY WILL
CONTINUE NEWD TODAY WITH RAIN CHANCES DIMINISHING DURING THE DAY.
COOLER TONIGHT WITH LOWS IN THE 30S BUT NO PRECIP EXPECTED.
NEXT SYSTEM DEVELOPS OVER TX ON TUE IN RESPONSE TO A VIGOROUS
UPPER WAVE THAT DIVES SEWD THROUGH THE ROCKIES EARLY TUE. THE SFC
LOW THEN MOVES NEWD THROUGH THE LOWER MS VALLEY TO A POSITION NEAR
MACON COUNTY EARLY WED MORNING. THIS IS A STRONG SFC LOW AND IS
PUSHING CONSIDERABLE MOISTURE AHEAD OF IT. THUS HPC IS SPITTING
OUT 1.25 TO 2.00 INCHES OF RAINFALL OVER THE AREA FOR THE DAY 1-3
TIME PERIOD. HAVE ALSO INCLUDED A MENTION OF TSTMS FOR SRN/SERN
COUNTIES ON TUE PM.
SO...HOW MUCH OF THAT RAINFALL WILL BE SNOW...APPARENTLY VERY
LITTLE. THE TRACK OF THE SFC LOW SEEMS TO BE A BIT FURTHER TO THE
WEST COMPARED WITH LAST NIGHTS RUN. THUS ANY SNOW AMOUNTS HAVE
BEEN REDUCED. IT APPEARS NOW THAT THE FAR NERN COUNTIES COULD GET
25 TO .50 INCHES OF SNOW LATE TUE NIGHT AND WED AM WITH THE NRN
CUMBERLAND PLATEAU GETTING LESS THAN A HALF INCH LATE WED AND WED
EVENING. ELSEWHERE A DUSTING IS POSSIBLE WED PM/EVE.
OF COURSE IT WILL BE TURNING COLDER FOR WED NGT AND THU WITH HIGHS
ON THU IN THE UPPER 30S TO NEAR 40 AND LOWS THU NGT IN THE MID 20S.
NO SIGNIFICANT WEATHER EXPECTED FOR THU THROUGH FRI AM.
SELY FLOW RETURNS THU NGT AS THE NEXT SYSTEM DEVELOPS OVER THE
LOWER PLAINS. MOISTURE PUSHES BACK INTO THE AREA ON FRI WITH A
CHANCE OF RAIN FOR FRI PM AND BEYOND. ONE CAUTION HERE...WITH THE
COLD AIR MASS STILL IN PLACE...IF THE PRECIP COMES IN EARLIER THAN
EXPECTED IT WOULD LIKELY HAVE A FREEZING RAIN COMPONENT.
RAIN CHANCES CONTINUE THROUGH FRI AND WILL LIKELY BE A MIXED BAG
OF RAIN AND SNOW. COLD AIR MOVES IN ON SAT WITH A CHANCE OF SNOW
IN THE MIDDLE AND EAST SECTION ON SAT NGT. HIGH PRESSURE OVER THE
AREA THROUGH SUN.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
929 AM CST MON DEC 24 2012
.UPDATE...FOR AVIATION FORECAST AT 15Z
EVEN THOUGH SURFACE LOW AND MID LEVEL SHORT WAVE ARE MOVING
THROUGH MIDDLE TENNESSEE AT 15Z SOME DRYING WILL TAKE PLACE IN THE
MID LEVELS WHILE MOISTURE IS EXPECTED TO REMAIN IN THE LOWER LEVELS.
FORECAST SOUNDINGS OFF THE LATEST RUC RUN KEEP LOW LEVEL MOISTURE
ACROSS THE MID STATE WHILE DRYING OUT MID LEVELS THROUGH A GOOD
PART OF THE DAY KEEPING MVFR AND OCCASIONAL IFR CONDTIONS AT BOTH
CLARKSVILLE AND NASHVILLE AND BASICALLY IFR CONDITIONS AT
CROSSVILLE LIKELY THROUGH THE DAYLIGHT HOURS. SATELLITE DOES SHOW
OCCASIONAL BREAKS IN THE OVERCAST (BINOVC) BUT THEY FILL IN RATHER
QUICKLY. LOW CLOUDS EXTEND ALL THE WAY BACK TO THE MISSISSIPPI
RIVER AT THIS TIME.
BOYD
&&
.AVIATION...
&&
.PREV DISCUSSION... /ISSUED 525 AM CST MON DEC 24 2012/
UPDATE...ADDED AVIATION SECTION FOR 12Z TAF`S.
AVIATION...BNA/CKV/CSV...COLD FRONT MOVING ACROSS MIDDLE
TENNESSEE THIS MORNING, BRINGING LIGHT TO MODERATE RAINFALL,
FOG, AND LOW CIGS. EXPECT IFR CONDITIONS FOR MUCH OF THE MORNING,
WITH CIGS IMPROVING DURING THE AFTERNOON AND EVENING AT BNA AND
CKV, AND REMAINING VFR OVERNIGHT. CSV WILL LIKELY EXPERIENCE LOW
CIGS THROUGHOUT THE DAY, WITH POSSIBLE LIFR CONDITIONS DEVELOPING
OVERNIGHT AS VV`S DROP TO NEAR ZERO AND VSBY AS LOW AS 1/2 MILE.
PREV DISCUSSION... /ISSUED 401 AM CST MON DEC 24 2012/
DISCUSSION...LOW PRESSURE SYSTEM CENTERED OVER THE MID MS VALLEY WILL
CONTINUE NEWD TODAY WITH RAIN CHANCES DIMINISHING DURING THE DAY.
COOLER TONIGHT WITH LOWS IN THE 30S BUT NO PRECIP EXPECTED.
NEXT SYSTEM DEVELOPS OVER TX ON TUE IN RESPONSE TO A VIGOROUS
UPPER WAVE THAT DIVES SEWD THROUGH THE ROCKIES EARLY TUE. THE SFC
LOW THEN MOVES NEWD THROUGH THE LOWER MS VALLEY TO A POSITION NEAR
MACON COUNTY EARLY WED MORNING. THIS IS A STRONG SFC LOW AND IS
PUSHING CONSIDERABLE MOISTURE AHEAD OF IT. THUS HPC IS SPITTING
OUT 1.25 TO 2.00 INCHES OF RAINFALL OVER THE AREA FOR THE DAY 1-3
TIME PERIOD. HAVE ALSO INCLUDED A MENTION OF TSTMS FOR SRN/SERN
COUNTIES ON TUE PM.
SO...HOW MUCH OF THAT RAINFALL WILL BE SNOW...APPARENTLY VERY
LITTLE. THE TRACK OF THE SFC LOW SEEMS TO BE A BIT FURTHER TO THE
WEST COMPARED WITH LAST NIGHTS RUN. THUS ANY SNOW AMOUNTS HAVE
BEEN REDUCED. IT APPEARS NOW THAT THE FAR NERN COUNTIES COULD GET
25 TO .50 INCHES OF SNOW LATE TUE NIGHT AND WED AM WITH THE NRN
CUMBERLAND PLATEAU GETTING LESS THAN A HALF INCH LATE WED AND WED
EVENING. ELSEWHERE A DUSTING IS POSSIBLE WED PM/EVE.
OF COURSE IT WILL BE TURNING COLDER FOR WED NGT AND THU WITH HIGHS
ON THU IN THE UPPER 30S TO NEAR 40 AND LOWS THU NGT IN THE MID 20S.
NO SIGNIFICANT WEATHER EXPECTED FOR THU THROUGH FRI AM.
SELY FLOW RETURNS THU NGT AS THE NEXT SYSTEM DEVELOPS OVER THE
LOWER PLAINS. MOISTURE PUSHES BACK INTO THE AREA ON FRI WITH A
CHANCE OF RAIN FOR FRI PM AND BEYOND. ONE CAUTION HERE...WITH THE
COLD AIR MASS STILL IN PLACE...IF THE PRECIP COMES IN EARLIER THAN
EXPECTED IT WOULD LIKELY HAVE A FREEZING RAIN COMPONENT.
RAIN CHANCES CONTINUE THROUGH FRI AND WILL LIKELY BE A MIXED BAG
OF RAIN AND SNOW. COLD AIR MOVES IN ON SAT WITH A CHANCE OF SNOW
IN THE MIDDLE AND EAST SECTION ON SAT NGT. HIGH PRESSURE OVER THE
AREA THROUGH SUN.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1200 AM EST MON DEC 24 2012
.SYNOPSIS...
A FAST MOVING AREA OF LOW PRESSURE WILL TRACK ACROSS THE AREA
LATE TONIGHT AND MONDAY. A STRONGER...MORE ROBUST STORM SYSTEM IS
LIKELY TO IMPACT THE REGION FOR THE MIDDLE PORTION OF THE WEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 1140 PM EST SUNDAY...
LIGHT RAIN MAY SCRAPE THE SE CWA BUT OVERALL SHOULD STAY MAINLY
DRY OVERNIGHT OUTSIDE OF THE SWRN CWA. RAIN SHOULD OVERSPREAD THE
MTNS AND FOOTHILLS BY MID MORNING MONDAY. STILL LOOKS LIKE MAINLY
A FREEZING RAIN OR RAIN SCENARIO NORTH OF I-64...WITH POCKETS OF
SNOW OR SLEET FURTHER NORTH. NO CHANGES TO THE WINTER WX ADVISORY.
PREVIOUS DISCUSSION...
GETTING A FEW SPRINKLES OR LIGHT RAIN INTO
THE NC MTNS. REGIONAL RADAR CONTINUES TO SHOW MAIN AXIS OF RAIN
FROM NORTHEAST TN SOUTHWEST TO NRN AL. AGAIN THE 12Z ECMWF AND THE
19Z WRF AND 21Z RUC SHOW THE BEST MATCH FOR THE CURRENT SCENARIO.
WITH THIS IN MIND THINK THE GFS/NAM OVERDONE ON QPF AND SPEED...SO
TIMED THE ONSET OF PRECIP A COUPLE TO 4 HOURS LATER. THIS IN HAS
ALLOWED TEMPS TO DROP LOWER THAN FORECAST INTO THE ALLEGHANY
HIGHLANDS AND GREENBRIER COUNTY WV AREA...AS HIGH CLOUDS UP THERE
HAVE BEEN THIN.
OVERNIGHT...THE CLOUD COVER THICKENS. ONE PIECE OF ENERGY WILL
MOVE EAST ALONG THE NC/VA BORDER WITH A SLIGHT CHANCE OF RAIN
HERE...BEFORE BETTER OMEGA ARRIVES INTO THE MTNS BY 12Z. MODEL
SOUNDINGS AND THERMAL PROFILES INDICATE A MAINLY RAIN/FREEZING
RAIN SCENARIO IN THE WINTER WX ADVISORY AREA...SOME SLEET OR SNOW
POSSIBLE MAINLY NRN BATH COUNTY/NRN GREENBRIER COUNTY. DESPITE THE
SLOW DOWN OF ONSET WILL LEAVE BEGINNING TIME OF ADVISORY AS IS.
MAY NEED TO EXTEND THE ADVISORY IN TIME TIL NOON BUT
OVERALL...WINTERY WX APPEARS TO BE ALL BUT GONE BY 10 AM...OUTSIDE
THE GREENBRIER/POCOHONTAS BORDER. WILL TAKE A LOOK AT NEWER DATA
TO SEE IF THE ADVISORY NEEDS TO BE EXTENDED IN TIME. MAIN CONCERN
IS THE COOLER TEMPS NOW AND THE FACT THAT THE SFC WIND BECOMES
MORE NE ACROSS THE HIGHLANDS AND ADJACENT VALLEYS BY MORNING.
COLD RAIN CONTINUES THROUGH THE DAY. MODEL QPF...WHICH MAY BE ON
THE HIGH SIDE...DURING THE RAIN IS ON THE ORDER OF A QUARTER TO A
THIRD OF AN INCH. WITH CLOUDS AND PRECIPITATION PLAYED HIGH
TEMPERATURES MONDAY ON THE COOLER SIDE OF MOS WITH READINGS FROM
THE MID 30S IN THE NORTH TO THE MID 40S IN THE SOUTHEAST.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 310 PM EST SUNDAY...
THE INFLUENCE OF A WEAK AREA OF LOW PRESSURE WILL BE WANING
CHRISTMAS EVE AS THE SYSTEM DEPARTS THE UPPER OHIO VALLEY AND FILLS
AS IT HEADS INTO NEW ENGLAND. A TRAILING COLD FRONT WILL PUSH ACROSS
THE CWA OVERNIGHT WITH LITTLE OR NO COLD AIR ADVECTION BEHIND
IT..H85 TEMPS REMAIN IN THE +2 TO +4 RANGE...SO DO NOT EXPECT POST-
FRONTAL UPSLOPE PRECIPITATION ISSUES. SKIES WILL CLEAR AT LEAST
PARTIALLY TOWARDS CHRISTMAS MORNING WITH TEMPS ONLY FALLING OFF INTO
LOW 30S IN COOLER MOUNTAIN VALLEYS TO UPPER 30S PIEDMONT...GENERALLY
5 TO 10F ABOVE CLIMO. WITH WEAK AND TRANSITORY SHORT-WAVE RIDGING
OVER THE AREA SHOULD START CHRISTMAS DAY UNDER CLEAR TO PARTLY
CLOUDY SKIES AND REMAINING FAIRLY MILD AS WELL WITH HIGHS INTO THE
40S MOUNTAINS AND LOW 50S PIEDMONT...AGAIN POSITIVE DEPARTURES OF
5F TO 10F. RAPID CHANGES LOOK TO BE IN THE OFFING HOWEVER AS ALL
MODELS ARE CONSISTENT IN DEVELOPING SURFACE LOW PRESSURE WHICH
STRENGTHENS IN THE GULF COAST AREA IN RESPONSE TO A VIGOROUS UPPER
JET DIGGING INTO THE SOUTHERN HIGH PLAINS LATE ON CHRISTMAS DAY.
MAY PRODUCE A WHITE CHRISTMAS NIGHT ACROSS PORTIONS OF
OKLAHOMA/ARKANSAS AREA. LOW IS FORECAST BY ALL DETERMINISTIC
MODELS (INCLUDING CMC WHICH HELD TO EASTERN TRACK YESTERDAY) AND
MAJORITY OF GFS ENSEMBLES TO TRACK WEST OF APPALACHIANS AND INTO
THE OHIO VALLEY WITH A BROAD AREA OF OVERRUNNING PRECIP LIFTING
NORTHWARD INTO THE REGION. PWATS SURGE FROM AROUND 0.5 INCHES TO
NEAR 1 INCH BY EARLY WEDNESDAY (APPROX +2 SD ABOVE NORMAL) SO
SHOULD BE PLENTY OF MOISTURE AVAILABLE. STORM TOTAL QPF 1 TO 1.5
INCHES NOT OUT OF THE QUESTION BY WEDNESDAY EVENING. WHILE THIS IS
EXPECTED TO BE PRIMARILY A RAIN EVENT...P- TYPE ISSUES MAY EXIST
AT THE OUTSET MAINLY IN THE FAR NW AS TRAPPED COLD AIR AT THE
SURFACE BRINGS A PERIOD OF SLEET OR MIXED PRECIP AND AGAIN IN THE
WAKE OF THE LOW AS UPSLOPE PRECIP DEVELOPS IN THE COLD AIR
ADVECTION. REGARDING THE INITIAL PERIOD...CLOUDS SPREADING IN
QUICKLY ON TUESDAY NIGHT MAY PRECLUDE MUCH OPPORTUNITY FOR TEMPS
TO RADIATE OFF FROM DAYTIME HIGHS WHICH SHOULD BE WELL ABOVE
FREEZING HENCE LIMITING FROZEN PCPN CHANCES. USING MODEL BLEND MIN
TEMPS FOR TUES NIGHT YIELDS SUB-32 LOWS IN ONLY FAR NW
GREENBRIER..BATH AND ROCKBRIDGE COUNTIES. MUCH COLDER WRAPS IN
BEHIND THE LOW WEDNESDAY NIGHT AS H85 TEMPS FALL TO -4C TO -8C
DEPENDING ON MODEL OF CHOICE AND NORTHWEST FLOW INCREASES..VERY
LIKELY TO SEE MOUNTAIN SNOWS IN FAVORED AREAS WITH ONLY FLURRIES
TOWARD THE BLUE RIDGE AND NEW RIVER VALLEYS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 255 PM EST SUNDAY...
DURING THE THURSDAY AND THURSDAY NIGHT PORTION OF THE FORECAST...THE
REGION WILL BE UNDER THE INFLUENCE OF STRONG NORTHWEST FLOW ON THE
BACKSIDE OF THE EXITING SYSTEM. THIS PATTERN WILL PROVIDE FOR VERY
GUSTY WINDS...ESPECIALLY AT THE RIDGE TOPS. WINDS AT 850 MB ARE
PROGGED TO BE IN THE 40 TO 50 KT RANGE. THIS MAY TRANSLATE TO
SURFACE GUSTS ONCE AGAIN IN THE ADVISORY TO NEAR WARNING LEVEL
RANGE. THE UPSLOPE SNOW MACHINE WILL AGAIN BE SWITCHED ON WITH THE
PREFERRED WEST FACING SLOPES OF WESTERN GREENBRIER COUNTY WEST
VIRGINIA...SOUTH INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA
EXPERIENCING MEASURABLE SNOWFALL. SOME AREAS MAY SEE ENHANCED SNOW
BANDS AS 850 MB TRAJECTORIES MAY TAP LAKE MICHIGAN.
THIS SYSTEM WINDS DOWN ON FRIDAY AS AN UPPER SHORTWAVE RIDGE PASSES
ACROSS THE REGION. THE BREAK IN THE PRECIPITATION WILL BE SHORT
LIVED. BY FRIDAY NIGHT...OVERRUNNING PRECIPITATION IN ADVANCE OF THE
NEXT SYSTEM MOVING THROUGH THE MID MISSISSIPPI VALLEY WILL REACH OUR
REGION. THE 12Z...7AM GFS IS ABOUT SIX HOURS SLOWER AS COMPARED TO
THE 12Z...7AM ECMWF SOLUTION BUT NOT ENOUGH TO FEEL RELATIVELY
CONFIDENT TO HAVE A LATE FRIDAY NIGHT START TIME FOR MOST OF THE
FORECAST REGION. WILL HAVE A SLIGHT CHANCE IN THE FAR WEST AND
SOUTHWEST BEFORE MIDNIGHT.
THE GFS/ECMWF BOTH HAVE THE FOCUS FOR GREATEST POTENTIAL OF
PRECIPITATION ACROSS THE AREA ON SATURDAY...WITH THE ECWMF JUST
SLIGHTLY QUICKER ON THE DEPARTURE OF THE MAIN AREA OF PRECIPITATION.
THE BIGGEST QUESTION DURING THE THURSDAY NIGHT AND FRIDAY TIME FRAME
IS PRECIPITATION TYPE. BOTH THE GFS AND ECMWF HAVE ENOUGH SUBTLE
DIFFERENCES WITH THE LOW LEVEL TEMPERATURE PROFILE THAT A MIXED BAG
OF PRECIPITATION IS POSSIBLE ACROSS THE AREA. THE MODEL GUIDANCE
FROM YESTERDAY FAVORED MORE OF A RAIN VERSUS FREEZING RAIN SCENARIO.
GUIDANCE FROM TODAY OFFERS A TREND TOWARD SLIGHTLY MILDER SURFACE
TEMPERATURES WITH THE 0C 850 MB ISOTHERM IN THE VICINITY OF THE
MIDDLE OF THE FORECAST AREA...THUS OPENING THE FULL GAMBIT OF
WEATHER OPTIONS. WITH A TREND TOWARD WARMER SURFACE
TEMPERATURES...WILL OFFER A RAIN VERSUS SNOW SOLUTION ACROSS THE
AREA BASED UPON SURFACE TEMPERATURES.
SATURDAY NIGHT INTO SUNDAY...WE SWITCH ON THE UPSLOPE SNOW MACHINE
AGAIN IN THE WAKE OF THE FRI/SAT SYSTEM. 850 MB WINDS ARE NOT
PROGGED TO BE AS ROBUST AS COMPARED TO THOSE ANTICIPATED THURSDAY
AND THURSDAY NIGHT. AS SUCH...BOTH SURFACE WIND GUSTS AND SNOW
AMOUNTS MAY NOT BE AS GREAT COMPARATIVELY.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 1150 PM EST SUNDAY...
LOWER CLOUDS ARRIVED QUICKER OVER BLF MAINLY DUE TO BREAK IN THE
HIGHER CLOUDS AND INCREASE DEWPOINTS FROM THE SOUTHWEST. STILL
LOOKING AT POOR FLYING CONDITIONS AT ALL TAF SITES BETWEEN 12Z AND
15Z LASTING THROUGH THIS TAF PERIOD. SOME LIGHT FREEZING RAIN IS
POSSIBLE AROUND 12Z AT LWB OTHERWISE RAIN AND FOG...TAPERING TO
DRIZZLE BY MONDAY EVENING.
CONDITIONS SHOULD IMPROVE SLOWLY LATE MONDAY NIGHT WITH VFR
EXPECTED BY CHRISTMAS DAY. HOWEVER THIS IS SHORT LIVED AS A
ANOTHER STORM SYSTEM MOVES INTO THE TN VALLEY FROM THE SOUTHWEST.
THIS MID WEEK STORM LOOKS TO BE MUCH STRONGER...WITH MODELS
DEEPENING THIS SYSTEM RAPIDLY AS IT MOVES ALONG THE SPINE OF THE
APPALACHIANS. THIS STORM WILL LIKELY HAVE A MUCH WIDER AREAL
IMPACT COMPARED TO MONDAYS WEAKER SYSTEM...WITH IMPLICATIONS THAT
IT WILL BECOME A MAJOR WINTER STORM FOR PARTS OF THE APPALACHIAN
SPINE INTO NEW ENGLAND...IMPACTING AIR TRAVEL FOR THE POST
HOLIDAY. ANOTHER LOW CENTER ARRIVE AROUND THE END OF THE WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY FROM 4 AM TO 10 AM EST MONDAY FOR
VAZ019-020.
NC...NONE.
WV...WINTER WEATHER ADVISORY FROM 4 AM TO 10 AM EST MONDAY FOR
WVZ045.
&&
$$
SYNOPSIS...PM
NEAR TERM...KK/WP
SHORT TERM...PC
LONG TERM...DS
AVIATION...KK/PM/WP
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1154 AM PST Mon Dec 24 2012
.SYNOPSIS...
Snow will end over the region today. Another storm system
will spread light snow into the Cascades Christmas morning,
reaching the Panhandle Christmas night. Drier but colder
conditions will arrive for the end of the work week and into the
weekend.
&&
.DISCUSSION...
Update to let the advisories for the Palouse and Blue Mtns expire.
Moderate to heavy snow still falling south of St Maries so will
continue the warning for the Central Panhandle Mtns. Web cams on
the Camas Prairie indicate that snow has stopped there for the
time being but HRRR runs still show a threat of more snow there so
will continue that Advisory until this afternoon`s forecast package.
Still struggling with low temperature forecast for tonight.
Guidance is all over the place. Clear skies and fresh snow certainly
bode well for a very cold night. But surface dew points are rather
high (lower 30s in many locations) which will cause fog to form
quickly, keeping us warmer. More on this topic with the afternoon
discussion. RJ
&&
.AVIATION...
18Z TAFS: Surface low over the central Panhandle continues to
produce snow over the southern Panhandle and southeast Washington.
This will gradually taper off this afternoon for improving
conditions at KPUW and KLWS. KGEG/KSFF/KCOE should continue to
improve as well with VFR weather this afternoon. Tough call is
tonight for fog and low clouds. Most TAF sites should see a few
hours of IFR conditions overnight, but conditions will likely be
quite variable between IFR and VFR hour to hour, so confidence is
low on the exact hours. By Tuesday morning the easterly winds
should cause improving conditions at KPUW/KCOE/KSFF/KGEG while
causing IFR weather at KEAT. RJ
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 30 17 30 25 29 22 / 0 10 30 60 50 30
Coeur d`Alene 32 18 31 26 30 24 / 20 10 20 60 60 40
Pullman 33 24 32 29 33 27 / 50 20 30 70 60 40
Lewiston 38 28 39 33 39 29 / 30 20 30 60 50 30
Colville 37 18 31 25 30 24 / 0 10 20 80 50 30
Sandpoint 32 15 29 26 28 25 / 0 10 10 60 60 30
Kellogg 33 20 28 25 31 25 / 60 40 10 80 70 40
Moses Lake 38 23 33 27 32 25 / 0 10 80 70 40 20
Wenatchee 36 21 29 24 29 24 / 0 10 90 80 40 20
Omak 34 18 28 21 28 21 / 0 10 90 80 40 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 4 PM PST this afternoon for Central
Panhandle Mountains.
Winter Weather Advisory until 4 PM PST this afternoon for Lewis
and Southern Nez Perce Counties.
WA...None.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS GREEN BAY WI
915 PM CST TUE DEC 25 2012
.UPDATE...TEMPS FALLING OFF THE CLIFF THIS EVENING SO LOWERED MINS
TONIGHT BEFORE HIGH LEVEL CLOUDS FILTER NORTHWARD. RADAR SHOWS A
BAND OF LAKE EFFECT SNOW SHOWERS WORKING INTO MANITOWOC COUNTY.
CLOUD TOPS ONLY AROUND 5 K TO MID LAKE WITH THIS BAND SO LIKELY
ONLY FLURRIES OR LIGHT SNOW SHOWERS AT THIS TIME.
TDH
&&
.PREV DISCUSSION...ISSUED AT 524 PM CST TUE DEC 25 2012...
SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED OVER THE NORTHERN GREAT PLAINS AND NOSING ACROSS
THE WESTERN GREAT LAKES. CLOUDS AND FLURRIES HAVE RETREATED NORTH
OF THE UPPER PENINSULA BORDER EARLY THIS AFTERNOON AND ARE NO LONGER
IMPACTING N-C WISCONSIN. MEANWHILE...LIGHT NE LOW LEVEL FLOW HAS
ALREADY STARTED TO DEVELOP OVER NORTHEAST WISCONSIN AND LAKE CLOUDS
ARE ALREADY PUSHING ACROSS THE FOX VALLEY. SNOW FLURRIES ARE
SHOWING UP ON RADAR JUST OFFSHORE THE KEWAUNEE COAST...AND EVEN WHAT
LOOKS LIKE A MID-LAKE BAND HAS BEEN MOVING EAST OVER CENTRAL LAKE
MICHIGAN. AS DEEPER AND STRONGER NE FLOW DEVELOPS LATER TONIGHT AND
WEDNESDAY...LAKE EFFECT SNOW CHANCES AND AMOUNTS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE RIDGE AXIS WILL BE EXTENDING ACROSS
NORTHERN WISCONSIN AND LAKE MICHIGAN AT THE START OF THE
EVENING...BUT WILL SHIFT NORTHWARD THROUGH THE NIGHT. AS STRONG LOW
PRESSURE MOVES OVER THE SOUTHERN OHIO VALLEY...WIND DIRECTION WILL
BECOME NORTHEASTERLY FROM THE SURFACE UP TO 700MB. 12Z GRB SOUNDING WAS
PRETTY DRY ABOVE 900MB THIS MORNING...BUT ONCE THE NE FLOW BECOMES
ESTABLISHED...OUR AIR WILL BE COMING FROM NORTHERN LAKE MICHIGAN
WHERE THE 12Z APX SOUNDING WAS CONSIDERABLY MORE SATURATED...UP TO
825MB. SINCE AMPLE CLOUD COVER ALREADY EXISTS OVER NORTHERN LAKE
MICHIGAN...AND SHOWING NO SIGNS OF DISSIPATING...SEE NO REASON WHY
THE LAKE CLOUDS COULD NOT CONTINUE TO PUSH ACROSS THE WESTERN FOX
VALLEY AND POSSIBLY EXPAND INTO CENTRAL WISCONSIN. LAKE EFFECT SNOW
POTENTIAL WILL IMPROVE THROUGH THE NIGHT WHEN 1000-850MB FLOW
STRENGTHENS TO 15 KTS. COMBINED WITH LENGTHENING FETCHES AND DELTA
T/S AROUND 16C...LAKE EFFECT SNOW SHOWERS LOOK LIKELY LATE TONIGHT
OVER E-C AND NE WISCONSIN. THINK IT WILL TAKE AWHILE FOR THE
MULTIPLE BANDS TO DEVELOP WITH WINDS LIGHT THIS EVENING. SO WILL
SHOW ACCUMS UP TO AN INCH OVER E-C WISCONSIN...MAINLY AFTER
MIDNIGHT. ELSEWHERE...CIRRUS WILL INCREASE FROM THE SW AFTER
MIDNIGHT AHEAD OF A NORTHERN STREAM SHORTWAVE. LOWS SLIGHTLY BELOW
ZERO OVER N-C WISCONSIN...TO THE UPPER TEENS NEAR LAKE MICHIGAN.
WEDNESDAY...NORTHEAST FLOW WILL CONTINUE UNABATED FOR THE ENTIRE
DAY. WITH A CIRRUS SHIELD OVERHEAD...DELTA T/S WILL REMAIN AROUND
15C WITH GREAT FETCH LENGTHS AND 1000-850MB WINDS BETWEEN 15-20KTS.
IN ADDITION...AN INCOMING SHORTWAVE TROUGH WILL LIFT INVERSION
HEIGHTS TO NEAR 800MB (PROBABLY UNDERESTIMATED DUE TO LAKE MICHIGAN
MODIFICATIONS) AND CREATE LARGE-SCALE ASCENT...WHICH WILL SUBTLY IMPROVE
LES POTENTIAL. WENT A LITTLE MORE BULLISH WILL SNOWFALL POTENTIAL
DUE TO THESE FACTORS...AND WILL SHOW 1-2 INCHES IN THE FORECAST. AM
CONCERNED THAT THE LONG FETCH LENGTHS AND A PERSISTENT WIND
DIRECTION WILL LEAD TO HIGHER AMOUNTS SINCE THIS COULD LEAD TO
ORGANIZED BANDING. ELSEWHERE...PLENTY OF CIRRUS OVERHEAD WILL CREATE
TO PARTLY SUNNY TO MOSTLY CLOUDY CONDITIONS. HIGHS MAINLY IN THE LOW
TO MID 20S.
LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
LAKE EFFECT SNOW SHOWERS WILL BE DIMINISHING EARLY IN THE PERIOD
AS LOW-LEVEL WINDS BACK AND SURFACE HIGH PRESSURE MOVES IN.
PACIFIC ENERGY MOVES ON SHORE WED AND QUICKLY MOVES INTO MIDWEST
BY LATE IN WEEK. ASSOCIATED SHORTWAVE TROF AND SURFACE WAVE MOVE
ACROSS REGION ON FRIDAY. ENOUGH MOISTURE ASSOCIATED WITH SYSTEM
TO PRODUCE LIGHT COATING OF SNOW ACROSS AT LEAST THE SOUTHERN
THIRD OR SO OF FORECAST AREA.
SEASONAL TEMPS DURING PERIOD AS ARCTIC AIR...FOR THE MOST PART...
REMAINS BOTTLE UP IN CANADA...NORTH AND NORTHEAST OF WI.
&&
.AVIATION...VFR CONDITIONS EXPECTED TONIGHT INTO WEDNESDAY OVER
NORTH CENTRAL AND MUCH OF CENTRAL WISCONSIN. MVFR CIGS DUE TO FLOW
OFF LAKE MICHIGAN WILL PREVAIL OVER EAST CENTRAL WISCONSIN THROUGH
WEDNESDAY. A FEW OF THESE MVFR CLOUDS MAY WORK INTO PARTS OF
CENTRAL WISCONSIN AT TIMES. LATER WEDNESDAY...SCATTERED MVFR VSBYS
DUE TO SNOW SHOWERS WILL BE POSSIBLE OVER EAST CENTRAL WISCONSIN
AND ESPECIALLY ALONG THE LAKE MICHIGAN SHORELINE.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
524 PM CST TUE DEC 25 2012
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED OVER THE NORTHERN GREAT PLAINS AND NOSING ACROSS
THE WESTERN GREAT LAKES. CLOUDS AND FLURRIES HAVE RETREATED NORTH
OF THE UPPER PENINSULA BORDER EARLY THIS AFTERNOON AND ARE NO LONGER
IMPACTING N-C WISCONSIN. MEANWHILE...LIGHT NE LOW LEVEL FLOW HAS
ALREADY STARTED TO DEVELOP OVER NORTHEAST WISCONSIN AND LAKE CLOUDS
ARE ALREADY PUSHING ACROSS THE FOX VALLEY. SNOW FLURRIES ARE
SHOWING UP ON RADAR JUST OFFSHORE THE KEWAUNEE COAST...AND EVEN WHAT
LOOKS LIKE A MID-LAKE BAND HAS BEEN MOVING EAST OVER CENTRAL LAKE
MICHIGAN. AS DEEPER AND STRONGER NE FLOW DEVELOPS LATER TONIGHT AND
WEDNESDAY...LAKE EFFECT SNOW CHANCES AND AMOUNTS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE RIDGE AXIS WILL BE EXTENDING ACROSS
NORTHERN WISCONSIN AND LAKE MICHIGAN AT THE START OF THE
EVENING...BUT WILL SHIFT NORTHWARD THROUGH THE NIGHT. AS STRONG LOW
PRESSURE MOVES OVER THE SOUTHERN OHIO VALLEY...WIND DIRECTION WILL
BECOME NORTHEASTERLY FROM THE SURFACE UP TO 700MB. 12Z GRB SOUNDING WAS
PRETTY DRY ABOVE 900MB THIS MORNING...BUT ONCE THE NE FLOW BECOMES
ESTABLISHED...OUR AIR WILL BE COMING FROM NORTHERN LAKE MICHIGAN
WHERE THE 12Z APX SOUNDING WAS CONSIDERABLY MORE SATURATED...UP TO
825MB. SINCE AMPLE CLOUD COVER ALREADY EXISTS OVER NORTHERN LAKE
MICHIGAN...AND SHOWING NO SIGNS OF DISSIPATING...SEE NO REASON WHY
THE LAKE CLOUDS COULD NOT CONTINUE TO PUSH ACROSS THE WESTERN FOX
VALLEY AND POSSIBLY EXPAND INTO CENTRAL WISCONSIN. LAKE EFFECT SNOW
POTENTIAL WILL IMPROVE THROUGH THE NIGHT WHEN 1000-850MB FLOW
STRENGTHENS TO 15 KTS. COMBINED WITH LENGTHENING FETCHES AND DELTA
T/S AROUND 16C...LAKE EFFECT SNOW SHOWERS LOOK LIKELY LATE TONIGHT
OVER E-C AND NE WISCONSIN. THINK IT WILL TAKE AWHILE FOR THE
MULTIPLE BANDS TO DEVELOP WITH WINDS LIGHT THIS EVENING. SO WILL
SHOW ACCUMS UP TO AN INCH OVER E-C WISCONSIN...MAINLY AFTER
MIDNIGHT. ELSEWHERE...CIRRUS WILL INCREASE FROM THE SW AFTER
MIDNIGHT AHEAD OF A NORTHERN STREAM SHORTWAVE. LOWS SLIGHTLY BELOW
ZERO OVER N-C WISCONSIN...TO THE UPPER TEENS NEAR LAKE MICHIGAN.
WEDNESDAY...NORTHEAST FLOW WILL CONTINUE UNABATED FOR THE ENTIRE
DAY. WITH A CIRRUS SHIELD OVERHEAD...DELTA T/S WILL REMAIN AROUND
15C WITH GREAT FETCH LENGTHS AND 1000-850MB WINDS BETWEEN 15-20KTS.
IN ADDITION...AN INCOMING SHORTWAVE TROUGH WILL LIFT INVERSION
HEIGHTS TO NEAR 800MB (PROBABLY UNDERESTIMATED DUE TO LAKE MICHIGAN
MODIFICATIONS) AND CREATE LARGE-SCALE ASCENT...WHICH WILL SUBTLY IMPROVE
LES POTENTIAL. WENT A LITTLE MORE BULLISH WILL SNOWFALL POTENTIAL
DUE TO THESE FACTORS...AND WILL SHOW 1-2 INCHES IN THE FORECAST. AM
CONCERNED THAT THE LONG FETCH LENGTHS AND A PERSISTENT WIND
DIRECTION WILL LEAD TO HIGHER AMOUNTS SINCE THIS COULD LEAD TO
ORGANIZED BANDING. ELSEWHERE...PLENTY OF CIRRUS OVERHEAD WILL CREATE
TO PARTLY SUNNY TO MOSTLY CLOUDY CONDITIONS. HIGHS MAINLY IN THE LOW
TO MID 20S.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
LAKE EFFECT SNOW SHOWERS WILL BE DIMINISHING EARLY IN THE PERIOD
AS LOW-LEVEL WINDS BACK AND SURFACE HIGH PRESSURE MOVES IN.
PACIFIC ENERGY MOVES ON SHORE WED AND QUICKLY MOVES INTO MIDWEST
BY LATE IN WEEK. ASSOCIATED SHORTWAVE TROF AND SURFACE WAVE MOVE
ACROSS REGION ON FRIDAY. ENOUGH MOISTURE ASSOCIATED WITH SYSTEM
TO PRODUCE LIGHT COATING OF SNOW ACROSS AT LEAST THE SOUTHERN
THIRD OR SO OF FORECAST AREA.
SEASONAL TEMPS DURING PERIOD AS ARCTIC AIR...FOR THE MOST PART...
REMAINS BOTTLE UP IN CANADA...NORTH AND NORTHEAST OF WI.
&&
.AVIATION...VFR CONDITIONS EXPECTED TONIGHT INTO WEDNESDAY OVER
NORTH CENTRAL AND MUCH OF CENTRAL WISCONSIN. MVFR CIGS DUE TO FLOW
OFF LAKE MICHIGAN WILL PREVAIL OVER EAST CENTRAL WISCONSIN THROUGH
WEDNESDAY. A FEW OF THESE MVFR CLOUDS MAY WORK INTO PARTS OF
CENTRAL WISCONSIN AT TIMES. LATER WEDNESDAY...SCATTERED MVFR VSBYS
DUE TO SNOW SHOWERS WILL BE POSSIBLE OVER EAST CENTRAL WISCONSIN
AND ESPECIALLY ALONG THE LAKE MICHIGAN SHORELINE.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
304 PM CST MON DEC 24 2012
.SHORT TERM...TONIGHT AND TUESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SHORTWAVE
TROUGH EXTENDING FROM NE WISCONSIN TO SOUTHERN LOWER MICHIGAN EARLY
THIS AFTERNOON. COMMA HEAD PRECIP WITH A LITTLE HELP FROM A LIGHT
LAKE EFFECT COMPONENT PRODUCED AREAS OF LIGHT SNOW THAT LINGERED
ACROSS NORTHEAST AND EAST-CENTRAL WISCONSIN THROUGH MID-AFTERNOON
BUT IS CURRENTLY EXITING TO THE EAST. WILL SHOW MOST OF THE PRECIP
ENDING BY 00Z THIS EVENING. IMPROVING CONDITIONS ARE OCCURRING OVER
CENTRAL AND NORTH-CENTRAL WISCONSIN WHERE BREAKS IN THE OVERCAST ARE
GROWING LARGER. HIGH PRESSURE IS BUILDING SOUTHWARD ACROSS THE
NORTHERN PLAINS WHERE SKIES ARE MOSTLY CLEAR AND COLD. THE MAIN
FORECAST CONCERNS INCLUDE THE TIMING OF THE END OF THE PRECIP AND
CLEARING TRENDS TONIGHT.
TONIGHT...THE SHORTWAVE TROUGH WILL BE WELL EAST OF THE REGION OVER
LOWER MICHIGAN AT THE START OF THE PERIOD. RESIDUAL MOISTURE WILL
TAKE AWHILE TO PUSH OUT OF THE REGION...SO WILL START THE EVENING
WITH MOSTLY CLOUDY CONDITIONS WITH A CHANCE OF FLURRIES OVER NE
WISCONSIN. BUT STRONG DRY AIR ADVECTION OVER NORTHWEST WISCONSIN
WILL SLOWLY MOVE SOUTHEAST THROUGH THE NIGHT AND GRADUALLY CLEAR OUT
THE SKIES ACROSS THE MAJORITY OF THE REGION. THE LONE EXCEPTION
WILL BE OVER N-C WISCONSIN WHERE LIGHT NW FLOW WILL CONTINUE TO
GENERATE LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS. TEMPS WILL FALL
TO NEAR ZERO OVER THE COLD SPOTS OF LINCOLN COUNTY WHERE SKIES WILL
CLEAR FIRST TO THE MIDDLE TEENS NEAR LAKE MICHIGAN WHERE CLOUDS WILL
CLEAR LAST.
TUESDAY...CANADIAN HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE
NORTHERN PLAINS AND NOSE ITS WAY ACROSS THE WESTERN GREAT LAKES.
LIGHT NORTHWEST FLOW WILL CONTINUE OFF LAKE SUPERIOR INTO N-C
WISCONSIN THROUGH THE MORNING...WHICH WILL KEEP SCT FLURRIES...AND
PARTLY TO MOSTLY CLOUDY CONDITIONS THERE. ELSEWHERE...MOSTLY SUNNY
CONDITIONS SHOULD PREVAIL. HIGHS RANGING FROM THE MID TEENS WEST TO
THE MID 20S EAST.
.LONG TERM...TUESDAY NIGHT THRU NEXT SUNDAY.
OVERALL...NO SIGNIFICANT CHANGES TO THE LONG TERM FORECAST. MAIN
FOCUS WAS TO TRY ADD A BIT MORE DETAIL REGARDING LES POTENTIAL
FOR LAKE MICHIGAN COUNTIES FOR WEDNESDAY.
MODELS CONTINUE TO BE IN FAIRLY GOOD AGREEMENT ON OVERALL TRACK OF
SOUTHERN STORM SYSTEM FORECAST TO TRACK TO THE OHIO VALLEY ON
WEDNESDAY. AS PREVIOUSLY FORECAST...THE NORTHERN FRINGE OF STRATIFORM
PRECIPITATION SHIELD WILL JUST CLIP EXTREME SOUTHEAST WISCONSIN
AND THE SOUTHERN PORTION OF LAKE MICHIGAN LATE WEDNESDAY. OTHER
THAN MIDDLE TO HIGH-LEVEL CLOUDS...THE MAIN IMPACT OF THIS SYSTEM
WILL BE TO CREATE A DEEP NORTHEASTERLY WIND FLOW EXTENDING FROM
THE SURFACE UP TO NEAR 700 MB. MAXIMUM OVERWATER BOUNDARY LAYER
FETCH ALSO IN PLACE BY 12Z WEDNESDAY. EXAMINATION OF MODIFIED
FORECAST GFS/NAM SOUNDINGS OVER LAKESHORE COUNTIES INDICATE A
FAIRLY DEEP MOIST AND UNSTABLE LAYER...WITH INVERSION HEIGHTS
APPROACHING 7000 FT AGL OVER WESTERN LAKE MICHIGAN. NAM/GFS ALSO
SUGGEST THAT MOIST LAYER MAY GROW DEEP ENOUGH TO PENETRATE INTO
FAVORABLE DENDRITIC GROWTH ZONE. WATER SURFACE TO 850 DELTA T
VALUES ON THE ORDER OF -16C TO -18C BY 12Z WEDNESDAY OVER THE
NORTHERN HALF OF LAKE MICHIGAN. GFS HAS BEEN FAIRLY CONSISTENT
LAST FEW RUNS...SPITTING OUT AREA OF QPF OVER NORTHERN LAKE
MICHIGAN AFTER 06Z WEDNESDAY AND BRINGING IT ONSHORE BY 12Z
WEDNESDAY. GIVEN OVERALL SYNOPTIC SETUP...NO REASON TO DISCOUNT
SIGNAL FROM GFS. BOTTOM LINE IS FAIRLY DECENT SET-UP FOR LAKE
EFFECT OVER MANITOWOC AND KEWAUNEE COUNTIES STARTING AROUND
DAYBREAK WEDNESDAY AND PERHAPS CONTINUING FOR MUCH OF THE DAY.
GIVEN BOUNDARY LAYER WINDS SPEEDS...WOULD EXPECT MULTIPLE AND SOMEWHAT
LES ORGANIZED LES BANDS RATHER THAN A SINGLE BAND. GIVEN THE
MESOSCALE NATURE OF LES PRECIPITATION WILL LET LATER SHIFTS TRY TO
REFINE THE DETAILS. FELT CONFIDENT ENOUGH AT THIS POINT TO AT
LEAST ADJUST POPS UPWARD INTO THE CHANCE CATEGORY ON WEDNESDAY.
FINALLY...GIVEN DEEP AND PERSISTENT NORHEASTERLY FLOW...ANY LES
BANDS THAT DEVELOP MAY BE ABLE TO PENETRATE AS FAR WEST AS THE FOX
RIVER VALLEY BEFORE WEAKNING. AS OHIO VALLEY STORM SYSTEM
CONTINUES TO MOVE NORTHEAST TO THE EASTERN SEABOARD...BOUNDARY
LAYER WINDS WILL BACK TO OFFSHORE WEDNESDAY NIGHT PUSHING ANY LES
BAND SOUTHWARD. FAIRLY TRANQUIL DAY ON THURSDAY AS WEAK HIGH
PRESSURE RIDGE MOVES ACROSS THE FORTECAST AREA.
THEN BY FRIDAY...SOUTHERN AND NORTHERN STREAM ENERGY BEGIN TO
APPROACH THE CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY.
UNCERTAINTY REMAINS AS TO HOW THESE FEATURES WILL INTERACT...WITH
CONCENSUS OF GUIDANCE SUGGESTING PERHAPS SOME PHASING OVER THE
OHIO VALLEY FRIDAY NIGHT. REGARDLESS...COMBINATION OF THESE
FEATURES SHOULD BE ABLE TO CREATE WAA ADVECTION REGIME AND DRAW
ADEQUATE MOISTURE NORTHWARD TOWARD THE FORECAST AREA TO GENERATE
BROAD AND GENERALLY LIGHT AREA OF QPF LIKELY TO SPREAD INTO THE
FORECAST AREA LATE ON FRIDAY INTO SATURDAY. LEANING MORE TOWARD
SOMEWHAT LESS ORGANIZED INVERTED TROUGH LOOK OF THE ECMWF AND
OPERATIONAL GFS FOR FRIDAY SYSTEM. INVERTED TROUGH AND CYCLONIC
FLOW MAY HANG BACK ACROSS THE WESTERN GREAT LAKES INTO
SATURDAY...THUS CONTINUE CHANCE POPS UNTIL THEN AS PER PREVIOUS
FORECAST.
DAYTIME TEMPERATURES SHOULD GRADUALLY MODERATE BY THE END OF THE
WEEK TO NEAR OF PERHAPS SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS THE STATE
THIS AFTERNOON AND EXIT BY EARLY THIS EVENING. SNOWFALL HAS BEEN
THE MOST VIGOROUS OVER NORTHEAST WISCONSIN WHERE VSBYS HAVE
OCCASIONALLY FALLEN BELOW A MILE. THINK THIS WILL CONTINUE THROUGH
MID-AFTERNOON BEFORE DIMINISHING. BUT WHATEVER SNOW FALLS SHOULD BE
LIGHT AND FLUFFY AND SHOULD BLOW OFF AIRCRAFT AND RUNWAYS EASILY.
CIGS ARE VARIABLE UPSTREAM OVER WESTERN WISCONSIN...BUT ONCE THE
SNOW EXITS...IMPROVEMENT IN CIGS SHOULD OCCUR TO MAINLY VFR EXCEPT
OVER N-C WISCONSIN WHERE FLOW WILL REMAIN OFF LAKE SUPERIOR. LIGHT
SNOW SHOWERS AND FLURRIES WILL CONTINUE THERE FOR MUCH OF THE NIGHT
WHILE THE REST OF THE AREA WILL SEE CLEARING FROM NW TO SE. MAINLY
VFR CONDITIONS ON TUESDAY WITH GOOD FLYING CONDITIONS.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/ESB
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1117 AM CST MON DEC 24 2012
.AVIATION/18Z TADS/...WIDESPREAD MFR CEILINGS WILL CONTINUE INTO
THE OVERNIGHT HOURS. ONE SHORTWAVE LIFTING OUT AND A SECONDARY
WAVE SWINGING THROUGH THIS AFTERNOON/EARLY EVENING MAINTAINING AT
LEAST A CHANCE OF LIGHT SNOW. APPEARS FZDZ POTENTIAL HAS WANED
WITH MODEL SOUNDINGS NOW SHOWING SATURATION TO THE -10C LEVEL.
HOWEVER HRRR MODEL WIPES OUT THE PRECIP WIPES THIS OUT AND
REDEVELOPS SECONDARY MAX IN SW WI. SOME FLURRIES COMING IN OFF THE
LAKE. TRAJECTORIES REMAIN FAVORABLE INTO TUESDAY MORNING THOUGH
DELTA T QUITE BORDERLINE. LOW LEVEL RH PROGS SHOW SOME CLEARING
TUESDAY MORNING.
PC
&&
.PREV DISCUSSION... /ISSUED 952 AM CST MON DEC 24 2012/
UPDATE...FREEZING DRIZZLE WEST AND SW OF MADISON IS VERY ISOLATED
AND WILL CONTINUE TO KEEP IT OUT OF THE FORECAST FOR THE AFTERNOON
WHEN TOP OF STRATUS LAYER EXTENDS UPWARD TO THE -10C LEVEL
RESULTING IN SNOW FLAKES VERSUS DRIZZLE. FOR THIS AFTERNOON...THE
NAM12 AND HRRR MODELS DEVELOP A BAND OF LIGHT SNOW NEAR AND WITHIN
THE SFC-925 MB TROUGH OVER SW WI INCLUDING
IOWA...LAFAYETTE...GREEN COUNTIES AND PORTIONS OF THE ADJACENT
COUNTIES. MAYBE A HALF AN INCH OF SNOW ACCUMULATION IN THESE
AREAS. OTHERWISE SMALL CHANCES OF SNOW OVER THE REMAINDER OF THE
AREA INCLUDING NEAR LAKE MI VIA VERY LIGHT LES.
GEHRING
PREV DISCUSSION... /ISSUED 405 AM CST MON DEC 24 2012/
TODAY...FORECAST CONFIDENCE IS MEDIUM.
MODELS HAVE BACKED OFF FREEZING DRIZZLE POTENTIAL AS COLUMN
MOISTENS FROM BELOW INTO THE -10C RANGE TO PROVIDE ENOUGH ICE
CRYSTALS FOR LIGHT SNOW. DRY MID LAYERS WILL LIMIT AMOUNTS...AS
BEST DEEP LAYER OMEGA WITH SHORT WAVE MOVES THROUGH THE REGION
PRIOR TO 18Z...BEFORE THE DRY LAYER SATURATES. COULD SEE SOME
SEEDER-FEEDER...BUT BEST CHANCE FOR ANY MEASURABLE QPF IS IN THE
WESTERN CWA IN REGION OF LOW-LEVEL CONVERGENCE ALONG AXIS OF
INVERTED SURFACE TROUGH.
LAKE-EFFECT SNOW SHOWER POTENTIAL ALSO HAS LESSENED AS DRY
DENDRITE GROWTH ZONE AND REDUCED FETCH LENGTH REDUCES PROBABILITY.
LOW-LEVEL LAPSE RATES ARE DECENT BUT DELTA T/S ARE CONDITIONAL SO
WILL LEAVE CHANCE PROBABILITY GOING. CLOUDS HAVE HELD OVERNIGHT
TEMPS UP AND EASTERLY FLOW SUPPORT BLENDED HIGH TEMPERATURES IN
THE MID 20S NW TO LOW TO MID 30S SOUTHEAST.
TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
LAKE-EFFECT SNOW POTENTIAL FADES DUE TO WINDS BACKING TO THE
NORTH...KEEPING ANY LAKE BANDS OFFSHORE. WILL KEEP A SLIGHT CHANCE
RIGHT ALONG THE SHORE IN THE EVENING. COLD AIR ADVECTION DROPS
OVERNIGHT LOWS TO AROUND 10 ABOVE NORTHWEST...TOT HE LOW MID 20S
RIGHT ALONG THE LAKE MICHIGAN SHORE.
CHRISTMAS DAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE IS
MEDIUM.
WEST SOUTHWEST FLOW AT 500MB ON SHORT TERM MODELS CHRISTMAS DAY
GIVES WAY TO A SHORTWAVE TROUGH PASSING THROUGH LATER ON
WEDNESDAY. THIS IS IN RESPONSE TO A CLOSED UPPER LOW MOVING
NORTHEASTWARD...BUT WELL SOUTHEAST OF THE AREA. RIDGING THEN
MOVES INTO THE REGION WEDNESDAY NIGHT.
AT THE SURFACE...CANADIAN HIGH PRESSURE LINGERS ACROSS THE
NORTHERN PLAINS INTO MINNESOTA CHRISTMAS DAY AND TUESDAY
NIGHT...BEFORE A HIGH PRESSURE RIDGE AXIS LINGERS IN MINNESOTA AND
IOWA WEDNESDAY AND WEDNESDAY NIGHT. STRONG LOW PRESSURE MOVES
NORTHEAST...BUT WELL SOUTHEAST OF THE AREA WEDNESDAY. NAM/GFS HAVE
OUTER EDGE OF PRECIPITATION SHIELD JUST MISSING FAR SOUTHEAST
WISCONSIN AT 00Z THURSDAY.
MAIN ISSUE CONTINUES TO BE LAKE EFFECT SNOW IN FAR SOUTHEAST
WISCONSIN FOR CHRISTMAS DAY THROUGH WEDNESDAY NIGHT.
MILWAUKEE/KENOSHA FORECAST SOUNDINGS FROM NAM/GFS CONTINUE TO SHOW
NORTHEAST LOW LEVEL FLOW...WITH MOISTURE AND PERSISTENT LOW LEVEL
CONVERGENCE PER GFS SURFACE TO 850MB FRONTOGENESIS RESPONSE.
FAVORABLE DELTA T VALUES OF 13 TO 16 DEGREES CELSIUS ARE
EXPECTED.
CHANCES FOR THESE LAKE EFFECT SNOW SHOWERS CHRISTMAS DAY/TUESDAY
NIGHT AND WEDNESDAY NIGHT HAVE LOWERED...AS THE LOW LEVEL MOISTURE
IS QUESTIONABLE WITH THE -10 DEGREE CELSIUS LEVEL NOT BEING
TAPPED. THIS WOULD RESULT IN CLOUDS WITH A FEW LIGHT SNOW
SHOWERS...WHICH WOULD NOT DROP ACCUMULATING SNOW PER LAKE EFFECT
SNOW FLOW CHART.
BEST SHOT IS WEDNESDAY...WITH THE BEST LOW LEVEL MOISTURE TAPPING
THE -10 DEGREE CELSIUS ICE CRYSTAL LAYER...AND MORE MID LEVEL
MOISTURE TO USE WITH PASSING SYSTEM TO THE SOUTHEAST. THIS SHOULD
RESULT IN ON AND OFF LIGHT LAKE EFFECT SNOW SHOWERS...ESPECIALLY
AROUND AND SOUTH OF MILWAUKEE. THESE LAKE EFFECT BANDS CAN BE
TRICKY TO FORECAST THIS FAR OUT...SO SOME MODIFICATION OF THE
FORECAST MAY OCCUR.
LAKE EFFECT SNOW FLOW CHART/SNOW TO LIQUID RATIOS SUGGESTS LIGHT
ACCUMULATIONS OF UP TO AN INCH WEDNESDAY SOUTH OF MILWAUKEE...WITH
LOWER AMOUNTS ELSEWHERE NEAR THE LAKE. THESE AMOUNTS COULD BE
HIGHER IF BAND PERSISTS ACROSS A LOCALIZED AREA...SO STAY TUNED TO
THE FORECAST.
THE REST OF THE AREA SHOULD SEE QUIET WEATHER...UNDER MOSTLY
CLOUDY SKIES. TEMPERATURES WILL CONTINUE TO BE AROUND OR JUST
BELOW SEASONAL NORMALS DURING THIS PERIOD.
THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM.
ECMWF/GFS BOTH SHOW A WEAK HIGH MOVING THROUGH THE REGION
THURSDAY...BRINGING QUIET WEATHER. THEY THEN GENERALLY SHOW A
SHORTWAVE TROUGH MOVING THROUGH THE REGION FRIDAY AND FRIDAY
NIGHT...WITH ANOTHER FOR SATURDAY INTO EARLY SATURDAY NIGHT.
A WEAK SURFACE LOW DEVELOPS IN THE CENTRAL PLAINS THURSDAY...AND
MOVES NORTHEAST ACROSS NORTHERN ILLINOIS FRIDAY NIGHT. THE ECMWF
IS MORE AGGRESSIVE WITH QPF THURSDAY NIGHT...WITH THE GFS/ECMWF
THEN IN GENERAL AGREEMENT WITH QPF FRIDAY INTO SATURDAY NIGHT.
USED CONSENSUS APPROACH WITH POPS AND TEMPERATURES IN THIS
PERIOD...WITH CHANCES FOR LIGHT SNOW AND COOL TEMPERATURES. HIGH
PRESSURE SLIDING INTO THE NORTHERN PLAINS SHOULD THEN BRING DRY
AIR INTO THE REGION SUNDAY.
AVIATION/12Z TAFS/...
WILL KEEP MVFR/IFR CONDITIONS GOING RIGHT THROUGH THE FORECAST
PERIOD AS STUBBORN LOW-LEVEL MOISTURE HANGS OVER REGION. FREEZING
DRIZZLE POTENTIAL TODAY HAS BEEN REDUCED WITH FORECAST SOUNDINGS
SHOWING MOISTENING UP FROM BELOW INTO THE -10C LEVEL...WHICH WOULD
PRODUCE SMALL ICE CRYSTALS VERSUS SUPER-COOLED DROPLETS. STILL A
CHANCE THIS MORNING WITH DEEP SYNOPTIC LIFT CROSSING THE REGION THIS
MORNING BUT NOT HIGH ENOUGH TO GO CATEGORICAL SO WILL LEAVE AS A
TEMPO ALONG WITH LIGHT SNOW.
DRY MID-LAYERS WILL LIMIT ANY SNOW AMOUNTS...WITH THE BEST CHANCE OF
MEASURABLE MAINLY IN THE SOUTHWEST FORECAST AREA CLOSE TO THE AXIS
OF INVERTED SURFACE TROUGH. WILL AGAIN LEAVE AS TEMPO VERSUS
CATEGORICAL. CONDITIONAL 850MB-WATER SURFACE TEMPERATURE
DIFFERENTIAL AND LITTLE TO NO MOISTENING ABOVE THE -10C LEVEL ON
FORECAST SOUNDINGS WILL LIMIT LAKE-EFFECT SNOW POTENTIAL AT KMKE AND
KENW.
MARINE...
WINDS AND WAVES WILL APPROACH SMALL CRAFT ADVISORY LEVELS
TUESDAY...AND WILL LIKELY REACH CRITERIA TUESDAY NIGHT WITH
INCREASING NORTHEAST WINDS AS PRESSURE GRADIENT TIGHTENS OVER REGION
AS LOW PRESSURE MOVES THROUGH TO THE SOUTH OF THE WESTERN GREAT
LAKES. THERE IS A CHANCE FOR LAKE-EFFECT SNOW SHOWERS TODAY IN THE
NEARSHORE WATERS...WITH THE CHANCE MOVING OUT TOWARD MID-LAKE BY
THIS EVENING AS WINDS TURN TO THE NORTH.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
952 AM CST MON DEC 24 2012
.UPDATE...FREEZING DRIZZLE WEST AND SW OF MADISON IS VERY ISOLATED
AND WILL CONTINUE TO KEEP IT OUT OF THE FORECAST FOR THE AFTERNOON
WHEN TOP OF STRATUS LAYER EXTENDS UPWARD TO THE -10C LEVEL
RESULTING IN SNOW FLAKES VERSUS DRIZZLE. FOR THIS AFTERNOON...THE
NAM12 AND HRRR MODELS DEVELOP A BAND OF LIGHT SNOW NEAR AND WITHIN
THE SFC-925 MB TROUGH OVER SW WI INCLUDING
IOWA...LAFAYETTE...GREEN COUNTIES AND PORTIONS OF THE ADJACENT
COUNTIES. MAYBE A HALF AN INCH OF SNOW ACCUMULATION IN THESE
AREAS. OTHERWISE SMALL CHANCES OF SNOW OVER THE REMAINDER OF THE
AREA INCLUDING NEAR LAKE MI VIA VERY LIGHT LES.
&&
.PREV DISCUSSION... /ISSUED 405 AM CST MON DEC 24 2012/
TODAY...FORECAST CONFIDENCE IS MEDIUM.
MODELS HAVE BACKED OFF FREEZING DRIZZLE POTENTIAL AS COLUMN
MOISTENS FROM BELOW INTO THE -10C RANGE TO PROVIDE ENOUGH ICE
CRYSTALS FOR LIGHT SNOW. DRY MID LAYERS WILL LIMIT AMOUNTS...AS
BEST DEEP LAYER OMEGA WITH SHORT WAVE MOVES THROUGH THE REGION
PRIOR TO 18Z...BEFORE THE DRY LAYER SATURATES. COULD SEE SOME
SEEDER-FEEDER...BUT BEST CHANCE FOR ANY MEASURABLE QPF IS IN THE
WESTERN CWA IN REGION OF LOW-LEVEL CONVERGENCE ALONG AXIS OF
INVERTED SURFACE TROUGH.
LAKE-EFFECT SNOW SHOWER POTENTIAL ALSO HAS LESSENED AS DRY
DENDRITE GROWTH ZONE AND REDUCED FETCH LENGTH REDUCES PROBABILITY.
LOW-LEVEL LAPSE RATES ARE DECENT BUT DELTA T/S ARE CONDITIONAL SO
WILL LEAVE CHANCE PROBABILITY GOING. CLOUDS HAVE HELD OVERNIGHT
TEMPS UP AND EASTERLY FLOW SUPPORT BLENDED HIGH TEMPERATURES IN
THE MID 20S NW TO LOW TO MID 30S SOUTHEAST.
TONIGHT...FORECAST CONFIDENCE IS MEDIUM.
LAKE-EFFECT SNOW POTENTIAL FADES DUE TO WINDS BACKING TO THE
NORTH...KEEPING ANY LAKE BANDS OFFSHORE. WILL KEEP A SLIGHT CHANCE
RIGHT ALONG THE SHORE IN THE EVENING. COLD AIR ADVECTION DROPS
OVERNIGHT LOWS TO AROUND 10 ABOVE NORTHWEST...TOT HE LOW MID 20S
RIGHT ALONG THE LAKE MICHIGAN SHORE.
CHRISTMAS DAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE IS
MEDIUM.
WEST SOUTHWEST FLOW AT 500MB ON SHORT TERM MODELS CHRISTMAS DAY
GIVES WAY TO A SHORTWAVE TROUGH PASSING THROUGH LATER ON
WEDNESDAY. THIS IS IN RESPONSE TO A CLOSED UPPER LOW MOVING
NORTHEASTWARD...BUT WELL SOUTHEAST OF THE AREA. RIDGING THEN
MOVES INTO THE REGION WEDNESDAY NIGHT.
AT THE SURFACE...CANADIAN HIGH PRESSURE LINGERS ACROSS THE
NORTHERN PLAINS INTO MINNESOTA CHRISTMAS DAY AND TUESDAY
NIGHT...BEFORE A HIGH PRESSURE RIDGE AXIS LINGERS IN MINNESOTA AND
IOWA WEDNESDAY AND WEDNESDAY NIGHT. STRONG LOW PRESSURE MOVES
NORTHEAST...BUT WELL SOUTHEAST OF THE AREA WEDNESDAY. NAM/GFS HAVE
OUTER EDGE OF PRECIPITATION SHIELD JUST MISSING FAR SOUTHEAST
WISCONSIN AT 00Z THURSDAY.
MAIN ISSUE CONTINUES TO BE LAKE EFFECT SNOW IN FAR SOUTHEAST
WISCONSIN FOR CHRISTMAS DAY THROUGH WEDNESDAY NIGHT.
MILWAUKEE/KENOSHA FORECAST SOUNDINGS FROM NAM/GFS CONTINUE TO SHOW
NORTHEAST LOW LEVEL FLOW...WITH MOISTURE AND PERSISTENT LOW LEVEL
CONVERGENCE PER GFS SURFACE TO 850MB FRONTOGENESIS RESPONSE.
FAVORABLE DELTA T VALUES OF 13 TO 16 DEGREES CELSIUS ARE
EXPECTED.
CHANCES FOR THESE LAKE EFFECT SNOW SHOWERS CHRISTMAS DAY/TUESDAY
NIGHT AND WEDNESDAY NIGHT HAVE LOWERED...AS THE LOW LEVEL MOISTURE
IS QUESTIONABLE WITH THE -10 DEGREE CELSIUS LEVEL NOT BEING
TAPPED. THIS WOULD RESULT IN CLOUDS WITH A FEW LIGHT SNOW
SHOWERS...WHICH WOULD NOT DROP ACCUMULATING SNOW PER LAKE EFFECT
SNOW FLOW CHART.
BEST SHOT IS WEDNESDAY...WITH THE BEST LOW LEVEL MOISTURE TAPPING
THE -10 DEGREE CELSIUS ICE CRYSTAL LAYER...AND MORE MID LEVEL
MOISTURE TO USE WITH PASSING SYSTEM TO THE SOUTHEAST. THIS SHOULD
RESULT IN ON AND OFF LIGHT LAKE EFFECT SNOW SHOWERS...ESPECIALLY
AROUND AND SOUTH OF MILWAUKEE. THESE LAKE EFFECT BANDS CAN BE
TRICKY TO FORECAST THIS FAR OUT...SO SOME MODIFICATION OF THE
FORECAST MAY OCCUR.
LAKE EFFECT SNOW FLOW CHART/SNOW TO LIQUID RATIOS SUGGESTS LIGHT
ACCUMULATIONS OF UP TO AN INCH WEDNESDAY SOUTH OF MILWAUKEE...WITH
LOWER AMOUNTS ELSEWHERE NEAR THE LAKE. THESE AMOUNTS COULD BE
HIGHER IF BAND PERSISTS ACROSS A LOCALIZED AREA...SO STAY TUNED TO
THE FORECAST.
THE REST OF THE AREA SHOULD SEE QUIET WEATHER...UNDER MOSTLY
CLOUDY SKIES. TEMPERATURES WILL CONTINUE TO BE AROUND OR JUST
BELOW SEASONAL NORMALS DURING THIS PERIOD.
THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM.
ECMWF/GFS BOTH SHOW A WEAK HIGH MOVING THROUGH THE REGION
THURSDAY...BRINGING QUIET WEATHER. THEY THEN GENERALLY SHOW A
SHORTWAVE TROUGH MOVING THROUGH THE REGION FRIDAY AND FRIDAY
NIGHT...WITH ANOTHER FOR SATURDAY INTO EARLY SATURDAY NIGHT.
A WEAK SURFACE LOW DEVELOPS IN THE CENTRAL PLAINS THURSDAY...AND
MOVES NORTHEAST ACROSS NORTHERN ILLINOIS FRIDAY NIGHT. THE ECMWF
IS MORE AGGRESSIVE WITH QPF THURSDAY NIGHT...WITH THE GFS/ECMWF
THEN IN GENERAL AGREEMENT WITH QPF FRIDAY INTO SATURDAY NIGHT.
USED CONSENSUS APPROACH WITH POPS AND TEMPERATURES IN THIS
PERIOD...WITH CHANCES FOR LIGHT SNOW AND COOL TEMPERATURES. HIGH
PRESSURE SLIDING INTO THE NORTHERN PLAINS SHOULD THEN BRING DRY
AIR INTO THE REGION SUNDAY.
AVIATION/12Z TAFS/...
WILL KEEP MVFR/IFR CONDITIONS GOING RIGHT THROUGH THE FORECAST
PERIOD AS STUBBORN LOW-LEVEL MOISTURE HANGS OVER REGION. FREEZING
DRIZZLE POTENTIAL TODAY HAS BEEN REDUCED WITH FORECAST SOUNDINGS
SHOWING MOISTENING UP FROM BELOW INTO THE -10C LEVEL...WHICH WOULD
PRODUCE SMALL ICE CRYSTALS VERSUS SUPER-COOLED DROPLETS. STILL A
CHANCE THIS MORNING WITH DEEP SYNOPTIC LIFT CROSSING THE REGION THIS
MORNING BUT NOT HIGH ENOUGH TO GO CATEGORICAL SO WILL LEAVE AS A
TEMPO ALONG WITH LIGHT SNOW.
DRY MID-LAYERS WILL LIMIT ANY SNOW AMOUNTS...WITH THE BEST CHANCE OF
MEASURABLE MAINLY IN THE SOUTHWEST FORECAST AREA CLOSE TO THE AXIS
OF INVERTED SURFACE TROUGH. WILL AGAIN LEAVE AS TEMPO VERSUS
CATEGORICAL. CONDITIONAL 850MB-WATER SURFACE TEMPERATURE
DIFFERENTIAL AND LITTLE TO NO MOISTENING ABOVE THE -10C LEVEL ON
FORECAST SOUNDINGS WILL LIMIT LAKE-EFFECT SNOW POTENTIAL AT KMKE AND
KENW.
MARINE...
WINDS AND WAVES WILL APPROACH SMALL CRAFT ADVISORY LEVELS
TUESDAY...AND WILL LIKELY REACH CRITERIA TUESDAY NIGHT WITH
INCREASING NORTHEAST WINDS AS PRESSURE GRADIENT TIGHTENS OVER REGION
AS LOW PRESSURE MOVES THROUGH TO THE SOUTH OF THE WESTERN GREAT
LAKES. THERE IS A CHANCE FOR LAKE-EFFECT SNOW SHOWERS TODAY IN THE
NEARSHORE WATERS...WITH THE CHANCE MOVING OUT TOWARD MID-LAKE BY
THIS EVENING AS WINDS TURN TO THE NORTH.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...GEHRING
TODAY/TONIGHT AND AVIATION/MARINE...REM
TUESDAY THROUGH SUNDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
255 AM CST MON DEC 24 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY
255 AM CST MON DEC 24 2012
IMMEDIATE FORECAST CONCERN IS FOCUSED ON LIGHT SNOW CHANCES TODAY
WITH THE POSSIBILITY OF SOME FREEZING DRIZZLE OVER A PORTION OF
NORTHEAST IA INTO FAR SOUTHWEST WI.
WATER VAPOR/IR IMAGERY SHOW A MID-LEVEL SHORTWAVE CIRCULATION
CENTERED NEAR THE ND/SD/MN BORDER. OUR FORECAST WAS AREA UNDER A
MIXTURE OF LOW/MID/HIGH CLOUDS AHEAD OF THE WAVE WHILE RADAR MOSAIC
SHOWED SOME LIGHT SNOW IMMEDIATELY TIED TO THE WAVE ACROSS CENTRAL
MN INTO EASTERN ND/SD.
THIS MID-LEVEL WAVE WILL MOVE EAST ACROSS THE AREA TODAY. MODELS
CONTINUE TO BE IN AGREEMENT IN PRODUCING VERY LIGHT QPF WITH THIS
FEATURE...WITH THE GFS MOST WIDESPREAD IN NATURE. MEANWHILE...HIRES
ARW/NMM MODELS SHOW A GENERAL BLOSSOMING DURING THE LATE MORNING
INTO THE AFTERNOON HOURS ACROSS THE SOUTHEAST HALF OF WI. THIS SEEMS
TO BE TIED WITH INCREASING LOW-LEVEL FETCH OF MOISTURE OFF LAKE
MICHIGAN COMBINED WITH CONVERGENCE ALONG AN INVERTED SURFACE TROUGH
WHICH IS A SURFACE REFLECTION OF THE MID-LEVEL WAVE. DIMINISHED
FREEZING DRIZZLE TO A SLIGHT CHANCE MENTION OVER PORTIONS OF
NORTHEAST IA INTO FAR SOUTHWEST WI DUE TO MODEL SOUNDINGS SHOWING
MORE ICE NOW FOR SNOW PRODUCTION. GENERALLY EXPECTING A COUPLE
TENTHS TO PERHAPS A HALF INCH OF SNOW ACCUMULATION ACROSS THE AREA
THROUGH TODAY.
HIGH PRESSURE WILL MOVE INTO THE AREA TONIGHT BEHIND THE DEPARTING
MID-LEVEL WAVE FOE DECREASING CLOUDS WITH TEMPERATURES DROPPING INTO
THE -1 TO +10F RANGE.
HIGH PRESSURE WILL REMAIN IN CONTROL ACROSS THE FORECAST AREA
THROUGH WEDNESDAY WHILE A STRONG LOW PRESSURE SYSTEM MAKES ITS WAY
THROUGH THE SOUTHERN PLAINS INTO THE APPALACHIANS. CLOUDS COULD BE
KIND OF TRICKY DUE TO A NORTHEAST AIRFLOW ACROSS LAKE SUPERIOR. THIS
MAY DRAG STRATUS/STRATOCUMULUS SOUTHWARD INTO THE AREA FROM TIME TO
TIME. KEPT SKIES PARTLY CLOUDY THROUGH THIS PERIOD FOR NOW.
OTHERWISE...TEMPERATURES CHRISTMAS DAY WILL BE ON THE CHILLY SIDE
WITH HIGHS ONLY TOPPING OFF IN THE SINGLE DIGITS TO THE TEENS.
WEDNESDAY LOOKS TO BE A FEW DEGREES WARMER BUT REMAINING BELOW
NORMAL WITH HIGHS IN THE TEENS TO THE MIDDLE 20S.
.LONG TERM...THURSDAY THROUGH SUNDAY
255 AM CST MON DEC 24 2012
24.00Z ECMWF/GFS REMAIN IN GOOD AGREEMENT THROUGH SUNDAY. BOTH
MODELS SHOW A RIDGE OF HIGH PRESSURE OVER THE AREA THROUGH
THURSDAY...THEN BRING A FAIRLY VIGOROUS MID-LEVEL TROUGH EJECTING
NORTHEAST OUT OF THE CENTRAL ROCKIES INTO THE AREA FRIDAY THROUGH
FRIDAY NIGHT FOR A CHANCE OF LIGHT SNOW. ANOTHER TROUGH OF LOW
PRESSURE DROPS SOUTHEAST OUT OF CANADA INTO THE AREA DURING THE DAY
SATURDAY FOR ANOTHER SHOT AT SOME LIGHT SNOW. A WEAK RIDGE OF HIGH
PRESSURE MOVES INTO THE AREA SATURDAY NIGHT/SUNDAY...PUSHING SNOW
CHANCES EASTWARD INTO THE GREAT LAKES REGION. OTHERWISE...APPEARS
TEMPERATURES WILL BE RIGHT AROUND NORMAL WITH LOWS IN THE TEENS AND
HIGHS IN THE 20S FOR THURSDAY THROUGH SATURDAY...THEN SLIPPING TO
BELOW NORMAL ON SUNDAY WITH HIGHS STRUGGLING INTO THE TEENS AND
LOWER 20S.
&&
.AVIATION...
1105 PM CST SUN DEC 23 2012
CLOUDS WILL BE ON THE INCREASE AND LOWER OVERNIGHT AS AN
UPPER LEVEL SHORTWAVE APPROACHES FROM THE PLAINS. LATEST FOG/STRATUS
SATELLITE IMAGERY AND SFC OBS POINT TO AN AREA OF SUB 3 KFT CLOUDS
OVER SD...HEADING SOUTHEAST. ANOTHER BAND OF LOW CLOUDS HUNG
WEST-EAST ACROSS IOWA...BUT WILL LIKELY STAY THERE. RAP13 DOING A
PRETTY DECENT JOB WITH THE LOW SATURATION...COMPARING RH TO
SATELLITE AND SOUNDINGS TO LAPS. RAP WOULD BRING THE LOW CLOUDS DUE
EAST THOUGH. SOME SAG SOUTH WITH THE UPPER LEVEL SHORTWAVE - PER
LATEST WATERVAPOR IMAGERY - BUT MORE EAST. WILL LEAN TOWARD A MORE
ESE MOVEMENT FOR THE LOW CLOUDS FOR NOW. PCPN WILL COME WITH THE
SHORTWAVE...AND IT LOOKS LIKE S-- FOR KRST/KLSE. BUFKIT SOUNDINGS
VIA THE RAP13/NAM12 SUGGESTIVE OF SOME POTENTIAL FOR -FZDZ TO THE
SOUTH EARLY MONDAY MORNING...BUT SOUTH OF THE TAF SITES. WILL STICK
WITH LIGHT SNOW FOR NOW. ANY SNOW ACCUMS WOULD BE MINIMAL.
THE SNOW SHOULD CLEAR TO THE EAST BY 18-21Z...BUT SOUNDINGS
CONTINUE TO FAVOR KEEPING LOW SATURATION UNDER AN INVERSION FOR THE
NIGHTTIME HOURS. THINK THERE SHOULD BE SOME IMPROVEMENT IN
CIGS...BUT COULD STAY AT LEAST MVFR THROUGH MUCH OF THE NIGHT...WITH
CLEARING THEN FOR CHRISTMAS DAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
255 AM CST MON DEC 24 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1105 PM CST SUN DEC 23 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
237 PM CST SUN DEC 23 2012
MAIN FORECAST CONCERNS REMAIN ON LIGHT PRECIPITATION CHANCES TONIGHT
THROUGH MONDAY...WITH THE POTENTIAL FOR SOME LIGHT FREEZING DRIZZLE
SOUTH OF INTERSTATE 90.
LATEST WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH MOVING INTO THE
WESTERN DAKOTAS MOVING EAST. A BROAD UPPER LOW WAS CENTERED OVER
JAMES BAY WITH NORTHWEST FLOW ALOFT NOTED ACROSS MUCH OF THE
WESTERN GREAT LAKES. SURFACE OBSERVATIONS SHOWED PERSISTENT
STRATUS STRETCHING ACROSS PORTIONS OF NORTHEAST IOWA THROUGH MUCH
OF SOUTHERN WISCONSIN. A FEW LAKE EFFECT CLOUDS WERE STREAMING
INTO FAR NORTHERN WISCONSIN ON NORTHERLY FLOW NEAR THE SURFACE.
SCATTED HIGH CIRRUS WILL CONTINUE FLOWING IN FROM THE WEST AHEAD
OF THE APPROACHING SHORTWAVE.
THE SHORTWAVE WILL MOVE EAST AND INTO THE UPPER MISSISSIPPI RIVER
VALLEY LATE TONIGHT. FORECAST MODELS CONTINUE TO BRING LIGHT
PRECIPITATION INTO THE AREA AND THIS HAS BEEN A CONSISTENT SIGNAL.
THERE IS A CONCERN TONIGHT REGARDING WEATHER OR NOT THERE WILL BE
ICE PRESENT ALOFT FOR THE PRODUCTION OF SNOW. FORECAST SOUNDINGS
SUGGEST THERE MAY NOT BE ICE DURING THE ONSET OF PRECIPITATION
SOUTH OF INTERSTATE 90. THIS APPEARS TO BE MORE OF AN ISSUE ALONG
AND EAST OF THE MISSISSIPPI RIVER DURING THE DAY ON MONDAY. 12Z KBLR
NAM SOUNDING SHOWS THE TOP OF THE CLOUD LAYER AROUND -8C BY 11Z
MONDAY MORNING...THEN COOLS AND DEEPENS RATHER QUICKLY DURING THE
MORNING HOURS WITH -10C AT THE TOP OF THE CLOUD BY 15Z. CANNOT RULE
OUT A PERIOD OF LIGHT FREEZING DRIZZLE ON MONDAY...WITH THE HIGHEST
CHANCES SOUTH OF INTERSTATE 90 AND MAINLY EAST OF THE MISSISSIPPI
RIVER. LOCATIONS NORTH OF INTERSTATE 90 WILL SEE LIGHT SNOW LATE
TONIGHT THROUGH MONDAY MORNING WITH ACCUMULATIONS OF UP TO 1 INCH
POSSIBLE. THE SHORTWAVE QUICKLY PUSHES INTO EASTERN WISCONSIN MONDAY
AFTERNOON BUT AN INVERTED SURFACE TROUGH LINGERS ACROSS SOUTHWEST
INTO CENTRAL WISCONSIN. THERE IS EXCELLENT AGREEMENT IN THE FORECAST
MODELS WITH THIS FEATURE REGARDING PLACEMENT...TIMING...AND
PRECIPITATION AMOUNT. DECIDED TO INCLUDE A STRIP OF LIKELY
PRECIPITATION CHANCES EXTENDING FROM CENTRAL WISCONSIN INTO FAR
SOUTHWEST WISCONSIN. WITH THE TOP OF THE CLOUD LAYER NOT REALLY
TAPPING INTO ICE WILL MAINTAIN PATCHY FREEZING DRIZZLE IN THE
FORECAST. PLAN ON MOSTLY CLOUDY SKIES ON MONDAY WITH HIGH
TEMPERATURES RANGING FROM THE LOWER 20S ACROSS NORTHERN WISCONSIN TO
THE UPPER TEENS ACROSS WESTERN SECTIONS OF NORTHEAST IOWA.
WEAK SURFACE HIGH PRESSURE WILL BUILD INTO THE UPPER MISSISSIPPI
RIVER VALLEY LATE CHRISTMAS EVE AND WILL REMAIN OVER THE REGION
THROUGH CHRISTMAS DAY. COLDER AIR IS EXPECTED TO MOVE INTO THE
REGION CHRISTMAS EVE WITH OVERNIGHT LOWS RANGING FROM THE UPPER
SINGLE DIGITS ACROSS FAR SOUTHWEST WISCONSIN TO THE THE SINGLE
DIGITS BLOW ZERO ACROSS PORTIONS OF SOUTHEAST MINNESOTA THROUGH
NORTH CENTRAL WISCONSIN. PLAN ON PARTLY SUNNY SKIES ACROSS THE AREA
ON CHRISTMAS DAY WITH HIGHS MAINLY IN THE TEENS. A FEW LOCATIONS
ACROSS CENTRAL INTO FAR SOUTHWEST WISCONSIN MAY APPROACH 20. A
POTENT UPPER TROUGH WILL MOVE ACROSS THE SOUTHERN PLAINS ON TUESDAY
AND LIFT INTO THE OHIO RIVER VALLEY REGION ON WEDNESDAY AND
EVENTUALLY INTO NEW ENGLAND WEDNESDAY NIGHT. THIS SYSTEM STILL LOOKS
TO STAY WELL EAST OF THE REGION. HIGH PRESSURE WILL REMAIN IN
CONTROL THROUGH WEDNESDAY NIGHT WITH DRY AND COOL CONDITIONS
EXPECTED. PLAN ON HIGHS ON WEDNESDAY RANGING FROM THE LOWER TEENS
ACROSS PORTIONS OF SOUTHEAST MINNESOTA TO THE LOWER 20S OVER CENTRAL
WISCONSIN
.LONG TERM...THURSDAY THROUGH SUNDAY
237 PM CST SUN DEC 23 2012
23.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT THROUGH
THURSDAY. THE ECMWF AND GFS ARE LEANING TOWARD SIMILAR SOLUTIONS
FRIDAY INTO SATURDAY WITH THE EVOLUTION OF A NORTHERN AND SOUTHERN
STREAM TROUGH. THE ECMWF WAS PREVIOUSLY TRYING TO MERGE THESE TWO
FEATURES OVER THE UPPER MISSISSIPPI RIVER VALLEY...POTENTIALLY
BRINGING SIGNIFICANT SNOW ACCUMULATIONS TO THE AREA ON SATURDAY.
THE ECMWF NOW SHOWS THE SOUTHERN WAVE DRIVING MUCH FURTHER EAST.
THE LATEST ECMWF SHOWS A VIGOROUS UPPER LOW TAKING SHAPE OVER THE
OHIO RIVER VALLEY ON SATURDAY. THE GFS CONTINUES TO KEEP A SERIES
OF OPEN WAVES AS THEY PROGRESS OVER THE FORECAST AREA. THE
NORTHERN WAVE LOOKS TO MOVE ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY FRIDAY INTO SATURDAY BRINGING CHANCES FOR LIGHT SNOW TO THE
AREA. MAJOR DIFFERENCES NOTED SUNDAY WITH THE ECMWF BUILDING A
RIDGE OVER THE CENTRAL CONUS AND THE GFS SHOWING COOL NORTHWEST
FLOW ALOFT OVER THE AREA. WILL LEAN TOWARD A MODEL CONSENSUS BLEND
THROUGH NEXT WEEKEND.
&&
.AVIATION...
1105 PM CST SUN DEC 23 2012
CLOUDS WILL BE ON THE INCREASE AND LOWER OVERNIGHT AS AN UPPER LEVEL
SHORTWAVE APPROACHES FROM THE PLAINS. LATEST FOG/STRATUS SATELLITE
IMAGERY AND SFC OBS POINT TO AN AREA OF SUB 3 KFT CLOUDS OVER
SD...HEADING SOUTHEAST. ANOTHER BAND OF LOW CLOUDS HUNG WEST-EAST
ACROSS IOWA...BUT WILL LIKELY STAY THERE. RAP13 DOING A PRETTY
DECENT JOB WITH THE LOW SATURATION...COMPARING RH TO SATELLITE AND
SOUNDINGS TO LAPS. RAP WOULD BRING THE LOW CLOUDS DUE EAST THOUGH.
SOME SAG SOUTH WITH THE UPPER LEVEL SHORTWAVE - PER LATEST
WATERVAPOR IMAGERY - BUT MORE EAST. WILL LEAN TOWARD A MORE ESE
MOVEMENT FOR THE LOW CLOUDS FOR NOW. PCPN WILL COME WITH THE
SHORTWAVE...AND IT LOOKS LIKE S-- FOR KRST/KLSE. BUFKIT SOUNDINGS
VIA THE RAP13/NAM12 SUGGESTIVE OF SOME POTENTIAL FOR -FZDZ TO THE
SOUTH EARLY MONDAY MORNING...BUT SOUTH OF THE TAF SITES. WILL STICK
WITH LIGHT SNOW FOR NOW. ANY SNOW ACCUMS WOULD BE MINIMAL.
THE SNOW SHOULD CLEAR TO THE EAST BY 18-21Z...BUT SOUNDINGS
CONTINUE TO FAVOR KEEPING LOW SATURATION UNDER AN INVERSION FOR THE
NIGHTTIME HOURS. THINK THERE SHOULD BE SOME IMPROVEMENT IN
CIGS...BUT COULD STAY AT LEAST MVFR THROUGH MUCH OF THE NIGHT...WITH
CLEARING THEN FOR CHRISTMAS DAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
237 PM CST SUN DEC 23 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1055 PM CST SUN DEC 23 2012
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND MONDAY
THE LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE STRETCHING FROM NORTHERN ALBERTA TO THE WESTERN GREAT LAKES
EARLY THIS AFTERNOON. LOW LEVEL STRATO-CU RAPIDLY DISSIPATED LATE
THIS MORNING ACROSS ALL BUT FAR NORTH-CENTRAL WISCONSIN. MEANWHILE
UPSTREAM...A SHORTWAVE TROUGH IS MOVING EAST OVER NORTH-DAKOTA WHERE
IT IS PRODUCING 1-3SM IN LIGHT SNOW. MID AND HIGH CLOUDS ARE
ALREADY ENTERING WESTERN WISCONSIN AHEAD OF THIS SYSTEM. AS THE
SHORTWAVE CONTINUES TO MOVE EAST THROUGH THE REGION LATE TONIGHT AND
TOMORROW...PRECIP CHANCES ARE THE MAIN FORECAST CONCERN.
TONIGHT...HIGH PRESSURE WILL BE IN PLACE FOR THE FIRST PART OF THE
EVENING WITH ONLY LIGHT NORTHWEST FLOW CREATING LOW STRATO-CU OVER
FAR N-C WISCONSIN. HOWEVER...MID AND HIGH CLOUDS WILL BE ON THE
INCREASE AND LOWERING THROUGH THE NIGHT AHEAD OF A SHORTWAVE TROUGH
MOVING EAST OVER THE NORTHERN PLAINS. THIS WAVE WILL BE APPROACHING
THE NORTHERN MISSISSIPPI VALLEY LATE TONIGHT...AND WILL PUSH DECENT
MID AND UPPER FORCING INTO THE REGION. 850MB LOW AND SURFACE
INVERTED TROUGH WILL HANG BACK OVER NE IOWA AND SOUTHEAST MINNESOTA
WHERE LOW LEVEL MOISTURE ARRIVES BY 12Z MONDAY. AS A
RESULT...PROGGED SOUNDINGS INDICATE A PROMINENT DRY WEDGE BETWEEN
925 AND 700MB THAT WILL HAVE TO SATURATE BEFORE PRECIP ARRIVES.
KEPT A SMALL CHANCE OF LIGHT SNOW OVER N-C WISCONSIN WHERE LOW
STRATO-CU COULD BECOME SEEDED BY THE LOWERING MID-DECK LATE. BUT THINK
THE REMAINING PART OF THE CWA WILL HAVE TO WAIT UNTIL MONDAY MORNING
FOR PRECIP CHANCES. LOWS IN THE MIDDLE SINGLE DIGITS NORTH TO THE
MID TEENS SOUTH.
MONDAY...THE SHORTWAVE TROUGH WILL MOVE ACROSS THE STATE THROUGH
ABOUT MID-AFTERNOON BEFORE DEPARTING TO THE EAST. WILL SEE
INCREASING AMOUNTS OF LOW AND MID-LEVEL MOISTURE...AND THE DRY WEDGE
IN THE SOUNDINGS ERODES OVER THE COURSE OF THE MORNING. DESPITE THE
850MB LOW AND INVERTED SURFACE TROUGH PASSING BY TO OUR
SOUTH...THINK WILL HAVE ENOUGH LIFT ABOVE 700MB FOR AT LEAST A
CHANCE OF LIGHT SNOW EVERYWHERE. THE BEST CHANCES WILL REMAIN OVER
N-C WISCONSIN AND THE LAKE MICHIGAN SHORELINE DUE TO THE AID OF A
SMALL LAKE EFFECT COMPONENT. THOUGH THE FORCING WILL EXIT THE STATE
DURING THE AFTERNOON...IT SEEMS THAT ENOUGH LOW LEVEL MOISTURE WILL
LINGER TO KEEP SKIES CLOUDY WITH SCATTERED FLURRY ACTIVITY. WILL
SHOW A HALF INCH TO AN INCH OF ACCUMULATION OVER N-C AND FAR NE
WISCONSIN. HIGHS MAINLY IN THE LOW TO MID 20S.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY.
WESTERN GREAT LAKES REGION LOOKS TO REMAIN ON THE NORTHERN
PERIPHERY OF RATHER ACTIVE SOUTHERN STREAM. OTHER THAN SOME
LINGERING LIGHT SNOW OR FLURRIES ACROSS THE FAR EASTERN SECTION OF
THE FORECAST AREA MONDAY EVENING WITH DEPARTING DISTURBANCE...GENERALLY
BENIGN WEATHER EXPECTED OVER THE FORECAST AREA THROUGH MOST OF THE
WORK WEEK. EXCEPTION WILL BE SOME MARGINAL LAKE EFFECT SNOW
CHANCES ALONG THE LAKE MICHIGAN SHORELINE AND THE TRADITIONAL LAKE
SUPERIOR SNOW BELT REGION. DAYTIME TEMPERATURES WILL START OUT A
FEW DEGREES BELOW NORMAL EARLY IN THE WEEK THEN GRADUALLY REBOUND
TO NEAR OR SLIGHTLY ABOVE NORMAL BY THE END OF THE WEEK.
MODELS CONTINUE TO MAINTAIN THAT AN IMPRESSIVE STORM SYSTEM WILL
TAKE SHAPE OVER THE SOUTHERN MISSISSIPPI VALLEY TUESDAY NIGHT THEN
HEAD NORTHEAST ACROSS THE OHIO VALLEY. SYSTEM WILL LIKELY GET
CLOSE ENOUGH TO BRING MID-HIGH CLOUDS INTO THE AREA LATE TUESDAY
NIGHT INTO WEDNESDAY. LIGHT STRATIFORM PRECIPITATION MAY CLIP
SOUTHEAST CORNER OF WISCONSIN...BUT SHOULD STAY SOUTH OF THE
FORECAST AREA. HOWEVER...WILL NEED TO KEEP AN EYE ON THIS SYSTEM
AS A SLIGHT JOG TO THE WEST COULD BRING A LITTLE LIGHT SNOW INTO
FAR SOUTHEAST PORTION OF THE FORECAST AREA. IN ADDITION...WEAK
NORTHERN STREAM DISTURBANCE IS ALSO FORECAST TO APPROACH THE
FORECAST AREA LATE WEDNESDAY AND POSSIBLY PHASE WITH MAIN SYSTEM
OVER LOWER MICHIGAN. THIS WEAK DISTURBANCE COULD ALSO BRING A
LITTLE LIGHT SNOW OR FLURRIES OVER EASTERN WISCONSIN LATE ON
WEDNESDAY. FINALLY...A PERIPHERAL EFFECT OF SYSTEM MOVING ACROSS
THE OHIO VALLEY WILL BE THAT A DEEP LAYER OF NORTHEAST WINDS WILL
DEVELOP AFTER 06Z WEDNESDAY AND PERSIST UNTIL ABOUT 06Z THURSDAY.
DESPITE A SOMEWHAT FAVORABLE OVERWATER FETCH...LOW-LEVEL
INSTABLITY NOT IMPRESSIVE. LOOKS LIKE THE MOST FAVORABLE WINDOW
FOR MARGINAL LES WOULD BE FROM 06Z TO 18Z WEDNESDAY. MAINTAINED
LOW CHANCE POPS ALONG THE LAKESHORE ESPECIALLY FROM KEWAUNEE
SOUTHWARD.
MEDIUM RANGE MODELS STILL HINTING AT ANOTHER SOUTHERN STREAM SYSTEM
TO EVOLVE OVER THE SOUTHERN MISSISSIPPI VALLEY FRIDAY...IN ADDITION
TO ANOTHER WEAKER PEICE OF NORTHERN STREAM ENERGY FORECAST TO
WORK ACROSS THE NORTHERN PLAINS. ALTHOUGH CONFIDENCE STILL LOW
WITH RESPECT ANY INTERACTION WITH THESE FEATURES...IT APPEARS THAT
A BROAD WAA REGIME DOWNSTREAM MAY GENERATE SOME LIGHT SNOW OVER
THE CENTRAL MISSISSIPPI VALLEY THAT COULD SPREAD INTO WISCONSIN
SOMETIME ON FRIDAY. FOR NOW...MAINTAINED CHANCE POPS FRIDAY INTO
SATURDAY.
&&
.AVIATION...THICKENING MID TO HIGH LEVEL CLOUDS VFR CONDITIONS
WILL CONTINUE OVERNIGHT. A WEAK DISTURBANCE DROPPING OVER THE
NORTHERN GREAT LAKES REGION ON MONDAY WILL BRING LIGHT SNOW TO
MUCH OF WISCONSIN. CIGS WILL LOWER TO MVFR LEVELS AS THE LIGHT
SNOW SPREADS FROM WEST TO EAST ACROSS THE STATE. VSBYS MAY LOWER
TO MVFR LEVELS FOR A FEW HOURS IN THE MORNING OVER NORTHERN
WISCONSIN.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
102 AM EST WED DEC 26 2012
.PREV DISCUSSION... /ISSUED 737 PM EST TUE DEC 25 2012/
.SEVERE STORMS INCLUDING A FEW TORNADOES LIKELY TONIGHT/EARLY WED
MORNING...
.UPDATE...
MAIN CONVECTIVE LINE AHEAD OF COLD FRONT IS PROGRESSING QUICKER
THAN ANTICIPATED ACROSS CENTRAL AL THIS EVENING AND ARE NOW
LOOKING AT POTENTIAL FOR SEVERE THREAT BEGINNING NEAR 03Z IN
WESTERN PORTIONS OF THE FORECAST AREA. SOME DISCRETE CELLS SHOWING
SIGNS OF ROTATION HAVE BEEN TRACKING MOSTLY NORTHWARD ACROSS
SOUTHEASTERN AL NEAR THE NORTHERN EXTENT OF THE WARM SECTOR. BASED
ON PROGGED SHORT RANGE ENSEMBLE MEMBERS... THE SOUTHWESTERN
PORTION OF CENTRAL GA LOOKS TO HAVE THE BETTER INSTABILITY
TONIGHT POTENTIALLY GETTING UP TO 500 J/KG OF MUCAPE...WHILE A
LINGERING HYBRID CAD DOME HAS PRIMARILY SERVED TO LIMIT
INSTABILITY FARTHER NORTHWARD. EARLIER SHOWER DEVELOPMENT DURING
THE DAY MAY HAVE REINFORCED THIS FEATURE AND WILL MONITOR
CONDITIONS CLOSELY. ALL CONSIDERED... BELIEVE BEST CHANCE FOR
ISOLATED TORNADO POTENTIAL WILL BE SOUTHERN/SOUTHWESTERN TIER
MAINLY SOUTH OF COLUMBUS AND MACON. MADE ADJUSTMENTS TO POP/WX
GRIDS BASED ON PROGRESSION OF AFOREMENTIONED CONVECTION.
BAKER
&&
PREV DISCUSSION... /ISSUED 309 PM EST TUE DEC 25 2012/
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
INGREDIENTS STILL COMING TOGETHER FOR NOCTURNAL SEVERE WEATHER EVENT
AFTER MIDNIGHT TONIGHT. 12Z RUNS HAVE CONTINUED TREND OF MORE
FAVORABLE PARAMETERS. 0-1KM BULK SHEAR OF 45-55KT NOW IN BOTH NAM
AND GFS...THOUGH THESE ARE SOMEWHAT EAST OF BEST MOISTURE/CAPE AXIS.
IN SPITE OF THIS...FCST SIG TOR PARAMETER VALUES ARE NOW 1.5-2.5 IN
GFS AND 4-5 WITH THE NAM. TORNADO THREAT IS QUITE HIGH FOR A COOL
SEASON QLCS EVENT.
TIMING ON GFS AND ECMWF HAS SHIFTED SLIGHTLY BACK TO BETTER MATCH
THE SLOWER NAM. LATEST HRRR NOW SIMILAR TO GFS TIMING. DUE TO
UNCERTAINTY IN MODELS AND WHETHER ANY PREFRONTAL STORM ACTIVITY WILL
DEVELOP...HAVE NOT TWEAKED TIMING BACK TOO MUCH. TOTAL RAINFALL
STILL HARD PRESSED TO EXCEED 2 INCHES. NO SIGNIFICANT FLOODING
PROBLEMS EXPECTED.
AFTER FRONT PASSES...PRECIP SHOULD END QUICKLY. WILL BE ISSUING A
WIND ADVISORY FOR THE ENTIRE AREA BUT STARTING A LITTLE SOONER IN
THE MOUNTAINS AS LOW LEVEL FLOW OF 50KTS COULD MIX DOWN TO HIGHER
ELEVATIONS. ALSO HAVE CONTINUED SLT CHC/CHC RAIN/SNOW SHOWER MIX
OVER PARTS OF FAR NE GA WED NIGHT. SHOULD NOT SEE ANY ACCUMULATION.
REST OF FCST LOOKS GOOD. WE WILL CONTINUE TO MONITOR THE SITUATION.
SNELSON
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE LONG TERM PORTION OF THE FORECAST BEGINS WITH WRAP AROUND
MOISTURE FROM THE BACK SIDE OF THE EXITING LOW PRESSURE SYSTEM
ACROSS N GA. COOLER AIR WILL ALSO BE FILTERING INTO THE STATE BUT IT
LOOKS LIKE THE BETTER MOISTURE WILL STAY FAR ENOUGH NORTH THAT IT
SHOULD NOT CAUSE ANY WINTER PRECIP ACROSS THE N GA MOUNTAINS THU
NIGHT/FRIDAY MORNING. HIGH PRESSURE BUILDS IN THURSDAY WITH MOISTURE
BEGINNING TO RETURN TO THE REGION FRIDAY. MOISTURE BEGINS PUSHING IN
AHEAD OF NEXT SYSTEM WHICH WILL BRING ANOTHER ROUND OF PRECIP TO THE
STATE FRIDAY NIGHT/SATURDAY. THIS NEXT SYSTEM DOES NOT LOOK AS
STRONG AS THE ONE THAT WILL MOVE THROUGH TONIGHT...SO WILL CONTINUE
WITH ONLY SHOWERS FOR NOW. THE MODELS SHOW THIS SECOND SYSTEM MOVING
THROUGH THE AREA VERY FAST WITH THE RAIN MOVING INTO W GA AROUND 06Z
SAT AND THE ENTIRE SYSTEM EXITING THE EAST SIDE OF THE STATE BY 18Z
SAT. A STRONG HIGH PRESSURE RIDGE BUILDS IN BEHIND THIS SECOND
SYSTEM AND IT LOOKS TO KEEP NORTH AND CENTRAL GEORGIA DRY SUNDAY AND
MONDAY.
01
&&
.HYDROLOGY...
FLASH FLOOD GUIDANCE REMAINS IN THE 1.5/2.5/3.0 FOR 1H 3H 6H
GUIDANCE RESPECTIVELY. THESE ARE SLIGHTLY REDUCED VALUES WITH RECENT
RAINS BUT LIKELY NOT SUFFICIENT FOR SIGNIFICANT FLOODING CONCERNS
GIVEN INITIAL LIGHT TO MODERATE RAIN AHEAD OF SYSTEM AND THEN
RAPID MOVEMENT OF COLD FRONT ONCE CONVECTIVELY ENHANCED BANDS SET
UP. STILL WILL BE CLOSELY MONITORING THE NEXT 24 HOUR FOR ANY
SHORT FUSE RIVER AND STREAM WARNINGS PRIMARILY.
&&
.AVIATION...
06Z UPDATE...
IFR TO NEAR HIGH END LIFR CIGS CONTINUE TO LINGER ACROSS MOST SITES
TONIGHT. HEIGHTS SHOULD IMPROVE TO MVFR LEVELS NEAR 1500-2500 FT
AFTER 08Z FROM THE WEST...AND ARE LIKELY TO LINGER ON INTO WEDNESDAY
NIGHT. AREA OF WIDESPREAD SHOWERS AND THUNDERSTORMS CONTINUES TO
PUSH EAST TONIGHT...WHILE BEST CHANCE FOR TSRA LOOKS TO BE SOUTH
NEAR KCSG AND KMCN...AND RA TO -SHRA LIKELY FARTHER NORTH THOUGH
CANNOT RULE OUT ISOLATED THUNDER. OVERNIGHT WINDS SE NEAR 12 KTS
GUSTING TO 20 KTS WITH POSSIBLE HIGHER VALUES FROM ANY STORM
DEVELOPMENT. MOST PRECIP SHOULD PUSH EAST OF THE SITES FROM ABOUT
10-12Z. WESTERLY WINDS OF NEAR 20 KTS WITH STRONG GUSTS OF 30-35
KTS ARE POSSIBLE FOR MOST SITES FROM ABOUT 17-01Z. VSBYS OF 4-6 SM
OVERNIGHT WITH POSSIBLY LOWER IN PRECIP AREAS... THEN P6SM AFTER
ABOUT 11Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ENDING TIME FOR PRECIPITATION.
HIGH CONFIDENCE ALL ELSE.
BAKER
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 52 31 51 30 / 80 0 0 0
ATLANTA 49 30 49 32 / 20 0 0 0
BLAIRSVILLE 48 28 45 28 / 80 20 0 0
CARTERSVILLE 50 31 46 27 / 20 0 0 0
COLUMBUS 51 33 53 31 / 20 0 0 0
GAINESVILLE 50 31 48 32 / 60 0 0 0
MACON 55 33 54 29 / 60 0 0 0
ROME 49 32 47 26 / 20 5 0 0
PEACHTREE CITY 49 31 50 25 / 20 0 0 0
VIDALIA 60 36 56 36 / 80 0 0 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS EVENING
FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BIBB...
BLECKLEY...BUTTS...CARROLL...CHATTAHOOCHEE...CLARKE...CLAYTON...
COBB...COWETA...CRAWFORD...CRISP...DEKALB...DODGE...DOOLY...
DOUGLAS...EMANUEL...FAYETTE...FORSYTH...GLASCOCK...GREENE...
GWINNETT...HALL...HANCOCK...HARALSON...HARRIS...HEARD...HENRY...
HOUSTON...JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...
LAMAR...LAURENS...MACON...MADISON...MARION...MERIWETHER...
MONROE...MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH
FULTON...OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE...
PULASKI...PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...
STEWART...SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR...
TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON...WALTON...WARREN...
WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES...WILKINSON.
TORNADO WATCH UNTIL 5 AM EST EARLY THIS MORNING FOR THE
FOLLOWING ZONES: CHATTAHOOCHEE...HARRIS...MACON...MARION...
MERIWETHER...MUSCOGEE...PIKE...SCHLEY...STEWART...SUMTER...
TALBOT...TAYLOR...TROUP...UPSON...WEBSTER.
WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR THE FOLLOWING
ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON...
FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS...
POLK...TOWNS...UNION...WALKER...WHITE...WHITFIELD.
&&
$$
SHORT TERM...SNELSON/BAKER
LONG TERM....01
AVIATION...BAKER
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1248 AM EST WED DEC 26 2012
.AVIATION... /06 UTC TAFS/
DETERIORATING MET CONDS ACRS NRN IN LATER THIS AM AS INTENSE STORM
SYSTEM ACRS WRN TN TO MOVE INTO THE SOUTHERN OHIO VALLEY
TODAY...THEN SHIFT ABRUPTLY EWD THIS EVENING AS FORCING FOCUS SHIFTS
TO MID ATL REGN. STILL CONDS LKLY INTO IFR/TEMPO LIFR ESP ACRS NERN
IN/WRN OH IN VCNTY OF BEST MSTR SOURCE. MINIMIZED FUEL ALT/LIFR AT
KSBN TIL AFTN HOURS...WELL ON WRN FRINGE OF SYSTEM. GRTR CONFIDENCE
WRT LIFR/EXTENDED FUEL ALT CONDS AT KFWA WITH HEAVIER SNOW BURST
TIMED TO BEST OVERLAP OF MESOSCALE FEATURES. RAPID IMPROVEMENT NOTED
AT END OF FCST PD...HIGHLIGHTING BRIEF/THOUGH SUBSTANTIVE IMPACT.
&&
.PREV DISCUSSION... /ISSUED 811 PM EST TUE DEC 25 2012/
UPDATE...
OBSERVATION/MODEL TRENDS CONT TO SUPPORT SNOW AND STRONG WINDS
CAUSING BLOWING AND DRIFTING SNOW MAINLY ACROSS SE 1/2 OF CWA WED
AS STRONG LOW OVER MS THIS EVE LIFTS NE TO VA BY WED EVE. LEADING
EDGE OF PRECIP ASSOCIATED WITH THE LOW WAS LIFTING NORTH INTO SRN
KY/SE MO ATTM... A LITTLE QUICKER THAN INDICATED BY LATEST MODEL
QPFS... BUT STILL PLENTY FAR ENOUGH AWAY FROM OUR CWA TO REMOVE
SLIGHT CHC POPS FOR THIS EVE IN THE GRIDS... WITH SNOW MENTION NOW
CONFINED TO AFT 06Z. OTRWS NO CHANGES TO AFTN FCST PLANNED THIS
EVE.
PREV DISCUSSION... /ISSUED 406 PM EST TUE DEC 25 2012/
SHORT TERM...
TONIGHT THROUGH WEDNESDAY NIGHT...
SIGNIFICANT WINTER STORM TO IMPACT MUCH OF THE CWA IN THE SHORT
TERM. WATER VAPOR IMAGERY SHOWING POTENT UPPER LOW DIGGING THROUGH
TEXAS. 12Z RAOB AND LATEST RAP ANALYSIS HAS 100KT+ UPPER JET COMING
INTO THE BASE OF THE TROUGH. ASSOCIATED SFC LOW NEAR TX/LA BORDER AT
18Z AND IS EXPECTED TO LIFT NE INTO THE CENTRAL TN VALLEY BY 12Z
WED. GOOD ISENT ASCENT AHEAD OF THIS SYSTEM ALONG THE 290-295K SFC
IS EXPECTED TO INITIATE PRECIP IN THE FAR SOUTHERN CWA AFTER
MIDNIGHT TONIGHT WITH LARGE SCALE FORCING TO INTENSIFY PRECIP TO
MOD-HVY SNOW AFTER 12Z. DESPITE A TREND TO A MORE SE TRACK...GOOD
DEFORMATION AXIS STILL SETS UP OVER SE CWA ALONG WITH SUBSTANTIAL
HEIGHT FALLS IN A DEEP MOISTURE COLUMN TO SUPPORT A WINDOW OF
OPPORTUNITY FOR WARNING CRITERIA SNOWFALL. STRONG GRADIENT BRINGING
15 TO 25 MPH WINDS WITH GUSTS TO 30 MPH LENDS FURTHER CREDENCE IN
MAINTAINING WINTER STORM WARNING. HAD TRANSITIONED REMAINING
COUNTIES IN THE WATCH OVER TO AN ADVISORY WITH GENERALLY 1-3/2-4
INCH AMOUNTS BUT ALSO ACCOMPANIED BY GUSTY WINDS FOR BLOWING SNOW.
POTENTIAL FOR MOD-HVY SNOW WILL BE SHORT-LIVED HOWEVER AS SYSTEM
WILL QUICKLY EXIT TOWARD THE EAST COAST WEDNESDAY NIGHT.
LONG TERM...
THURSDAY THROUGH TUESDAY...THE CHALLENGES THIS PERIOD INCLUDE
CHANCES FOR SNOW WITH THE PASSAGE OF A WEAK UPPER TROF LATE THIS
WEEK. ALSO...HIGH AND LOW TEMPERATURES WITH AN EXTENDED PERIOD OF
COLD AIR AND SNOW COVER OVER AT LEAST PART OF THE FORECAST AREA WILL
PROVIDE ADDITIONAL CHALLENGES. FOR THIS PACKAGE...FAVORED THE GFS.
THE GFS HAS AT LEAST AS GOOD OF RUN TO RUN CONSISTENCY AS THE ECMWF
AND APPEARS TO BE HANDLING THIS PATTERN REASONABLY WELL. THE GFS
TIMING OF THE SYSTEM LATE THIS WEEK HAS ALSO BEEN CONSISTENT FOR THE
PAST 8 RUNS AND APPEARS ON TRACK. ALSO...THE OPERATION MOS AND
ENSEMBLE MOS HAS BEEN RELATIVELY STABLE IN ITS OUTPUT FOR SEVERAL
DAYS AND APPEARS IN LINE. HAVE MODIFIED HIGH AND LOW TEMPS GIVEN
SNOW FIELD CONSIDERATIONS.
AT THE START OF THE PERIOD...DOWNWARD MOTION WILL HAVE INCREASED
SIGNIFICANTLY AS EVIDENCE OF NET ISENTROPIC ADIABATIC OMEGA WITH A
DRYING OF THE MID LEVELS. AS A RESULT...HAVE REMOVED LINGERING
FLURRIES THURSDAY OVER NW OHIO. FOR THE REST OF THE PERIOD...TRIED
TO PUT SOME DETAIL IN THE TIMING OF THE UPPER LEVEL TROF THIS
WEEKEND AND SUBSEQUENT LAKE EFFECT SNOW SHOWERS. THERE IS LITTLE
MOISTURE TO WORK WITH AND FORCING IS WEAK...SO ANY SNOW AMOUNTS
SHOULD BE LIGHT. LAKE EFFECT PARAMETERS ARE VERY MARGINAL WITH A
LIMITED FETCH. DELTA T VALUES GENERALLY SHOULD BE 10 TO 14 WITH LOW
INVERSION HEIGHTS. REMOVED THE CHANCE FOR SNOW SUNDAY AND SUNDAY
NIGHT. GFS BUFKIT PROFILE SUPPORTS FREEZING DRIZZLE OVER SNOW GIVEN
THE LACK OF ICE INDUCED IN THE CLOUD LAYER. TEMPERATURES IN A DEEP
LAYER WARM ABOVE -10C. NOT OPTIMISTIC ABOUT SNOW CHANCES MONDAY...
BUT FOR THE SAKE OF CONSISTENCY AND LINGERING UNCERTAINTY ABOUT
EARLY NEXT WEEK...LEFT LAKE EFFECT SNOW SHOWERS IN THE FORECAST
MONDAY.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR INZ009.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR
INZ018-025>027-032>034.
WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST
THURSDAY FOR INZ005>008.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM EST WEDNESDAY FOR
INZ015>017-020-022>024.
MI...WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST
THURSDAY FOR MIZ079>081.
OH...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY
FOR OHZ001-002-004-005.
WINTER STORM WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR
OHZ015-016-024-025.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THURSDAY FOR LMZ043-046.
&&
$$
SHORT TERM...JAL
LONG TERM...SKIPPER
UPDATE...JT
AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1153 PM CST TUE DEC 25 2012
.UPDATE...
ISSUED AT 1153 PM CST TUE DEC 25 2012
UPDATED AVIATION SECTION FOR 06Z TAF PACKAGE.
UPDATE ISSUED AT 920 PM CST TUE DEC 25 2012
ONLY A SLIGHT SOUTHEASTWARD ADJUSTMENT WILL BE MADE TO THE
HEAVY SNOW AXIS. IT WILL BE DIFFICULT TO SEE THE ADJUSTMENTS TO
THE GENERAL FORECAST PRODUCTS. AT THIS POINT THERE IS NOT
MUCH REASON TO KEEP HANGING OUT FOR EACH NEW MODEL RUN TO
GET CUTE WITH TOTALS. A SUMMATION OF SOLUTIONS OF THE PAST
SEVERAL DAYS IN ESSENCE YIELDS THE BEST AXIS ALONG AND JUST NORTH
AND WEST OF THE OHIO UP TOWARD THE WABASH RIVER VALLEY REGION
WITH AMOUNTS TAPERING OFF CONSIDERABLY HEADING EAST ACROSS
WEST KENTUCKY. WEST KENTUCKY WILL CONTINUE TO BE THE REAL
CHALLENGE REGION WHERE AMOUNTS...SOMEWHERE WILL TAPER DOWN
CONSIDERABLY. NO CHANGES TO THE BLIZZARD WARNING EITHER.
EARLY ONSET PRECIPITATION HAS BEEN A MIX OF RAIN...SLEET AND
SNOW. AREAS FROM ALONG THE OHIO NORTH AND WEST INTO SEMO AND
SRN IL WILL TRANSITION QUICKLY TO SNOW AS THE UPPER SYSTEM
EJECTS NE...AND THE PRECIP SHIELD SEEN OVER ARKANSAS EXPANDS
NORTH AND EAST INTO THE REGION. NEEDLESS TO SAY...CONDITIONS
WILL DETERIORATE RAPIDLY FROM SW TO NE ACROSS THE REGION
FROM 10 PM ON INTO THE OVERNIGHT...MAKING TRAVEL CONDITIONS
DANGEROUS...LIFE THREATENING. BLOWING SNOW AND DRIFTS AS
WELL WITH THE STRONG AND GUSTY WINDS.
..NOLES..
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE NEAR TERM...AN INTENSIFYING BAND OF MIXED PRECIPITATION IS
LIFTING NORTHWARD FROM NORTHERN ARKANSAS AS OF 20Z. THIS BAND IS
ASSOCIATED WITH STRONG WARM ADVECTION ON EASTERLY FLOW IN THE
850/700 MB LAYER. RUC MODEL BRINGS THE ZONE OF STRONG MID LEVEL
WARM ADVECTION AND ASSOCIATED PRECIP INTO SOUTHEAST MISSOURI BY
00Z. PRECIP TYPE WILL GRADUALLY CHANGE TO SNOW BY MID EVENING IN
SE MISSOURI...ONCE THE WARM ADVECTION DIMINISHES AND FRONTOGENETIC
FORCING TAKES OVER. INTERESTING TO NOTE THAT RUC MODEL THERMAL
PROFILES ARE SOMEWHAT COLDER THAN GFS/NAM PROFILES THIS EVENING.
LATER IN THE EVENING...IN THE 03Z TO 06Z TIME FRAME...RUC
INDICATES THE MAIN FORCING MECHANISM WILL BECOME MID LEVEL
FRONTOGENESIS /850 TO 700 MB LAYER/. THIS WILL RESULT IN LOCALLY
HEAVY PRECIPITATION ACQUIRING MORE OF A BANDED CHARACTER AS IT
OVERSPREADS THE REMAINDER OF THE FORECAST AREA.
LOOKING AT THE 12Z MODEL SUITE...MODELS ARE ALMOST IN LOCKSTEP AS
THE EVENT IS NOW WITHIN THE NEXT 24 HOURS. THE PRIMARY ISSUES ARE
PRECIPITATION TYPE AND LOCATION OF THE DEFORMATION ZONE /HEAVIEST
QPF/.
THE SWATH OF HEAVIEST QPF IS EXPECTED TO OCCUR UNDER THE DEFORMATION
ZONE TO THE NORTHWEST OF THE MID LEVEL LOW. AN INTENSE/COMPACT 500
MB LOW WILL TRACK EAST/NORTHEAST ACROSS TENNESSEE TONIGHT AND
WEDNESDAY. THE ASSOCIATED DEFORMATION ZONE WILL BE ACROSS SE
MISSOURI AND ROUGHLY ALONG AND NORTHWEST OF THE OHIO RIVER. THIS IS
EVIDENT IN THE 12Z GFS...WHICH SHOWS PRONOUNCED MID LEVEL
FRONTOGENETICAL FORCING AND HEAVY QPF COLOCATED WITH EACH OTHER. MOST
OTHER MODEL QPF GUIDANCE INDICATES THE DEFORMATION ZONE LOCATION
IN THE SAME AREA. THEREFORE...EXPECT THE SWATH OF HEAVIEST
SNOWFALL TO OCCUR WITHIN THAT AREA...MAINLY NW OF A KEVV/KPAH LINE.
ONE MAJOR CAVEAT IS PRECIP TYPE. THE MODELS HAVE ACTUALLY WARMED
SOMEWHAT IN THE 800 TO 900 MB LAYER TONIGHT DUE TO PRONOUNCED
EASTERLY FLOW AT 850 MB. ABOVE FREEZING AIR IS FORECAST TO WRAP
WESTWARD AROUND THE TOP OF THE 850 MB LOW...WHICH WILL DELAY THE
CHANGEOVER TO SNOW ALONG AND EAST OF THE KEVV/KPAH CORRIDOR. BASED
ON A BLEND OF SREF/NAM/GFS THERMAL PROFILES...THE CHANGEOVER TO SNOW
FROM KPAH TO KEVV WOULD BE IN THE 07Z TO 11Z TIME FRAME. THIS WOULD
CUT DOWN SIGNIFICANTLY ON FORECAST SNOWFALL AMOUNTS...THOUGH A FEW
HOURS OF HEAVY WET SNOW AND BLIZZARD CONDITIONS ARE STILL EXPECTED.
MODEL BOUNDARY LAYER AND 850 MB TEMPS IN THE FAR SOUTHEAST DO NOT
SUPPORT MUCH SNOW IN THE KHOP AREA...AND THE WINTER STORM WATCH
HAS BEEN DISCONTINUED FOR THAT AREA.
WHERE THE BULK OF THE PRECIPITATION IS ALL SNOW NORTH AND WEST OF
THE KEVV/KPAH CORRIDOR...THERE IS HIGH CONFIDENCE IN A CRIPPLING
BLIZZARD. SNOWFALL AMOUNTS WITHIN THE DEFORMATION ZONE AXIS SHOULD
REACH A FOOT OR SO. LOOKING AT BUFKIT MOMENTUM TRANSFER...BOTH THE
NAM AND GFS INDICATE A HIGH POTENTIAL FOR GUSTS TO AT LEAST 35
KNOTS. THE SREF SHOWS A 50 PERCENT CHANCE OF SUSTAINED WINDS OVER 25
KNOTS IN SE MISSOURI. DESPITE THE HEAVY WET NATURE OF THE
SNOW...DRIFTS WILL BE MEASURED IN FEET IN THE SWATH OF HEAVIEST
SNOW. THE COMBINATION OF HEAVY WET SNOW AND WIND WILL LIKELY CAUSE
SOME POWER OUTAGES.
AS FOR THE TIMING OF THE EVENT...PRECIP WILL SPREAD NORTH ACROSS
THE ENTIRE FORECAST AREA THROUGH 06Z. THE HEAVIEST PRECIP WILL
OCCUR ROUGHLY FROM 03Z TO 12Z. THE DEFORMATION ZONE WILL LIFT OUT
WEDNESDAY MORNING...BUT WINDS WILL NOT BEGIN TO DIMINISH UNTIL AT
LEAST 18Z. THE STRONG WINDS WILL CONTINUE TO RESULT IN EXTENSIVE
BLOWING AND DRIFTING IN THE HEAVY SNOW AREA.
.LONG TERM /THURSDAY THROUGH NEXT TUESDAY NIGHT/...
ISSUED AT 318 PM CST TUE DEC 25 2012
IN THE EXTENDED FORECAST PERIOD...SHORTWAVE RIDGING ALOFT WILL
DOMINATE DURING FROM THURSDAY THROUGH THE EARLY MORNING HOURS ON
FRIDAY. ALTHOUGH THERE WILL BE A LITTLE MORE INSOLATION /SUNSHINE/
AVAILABLE...THERE WILL STILL BE WEAK COLD AIR ADVECTION OVER THE
EXPECTED SNOW FIELD FROM THE TUESDAY NIGHT/WEDNESDAY MORNING WINTER
STORM. WITH THIS IN MIND...LOWERED TEMPERATURES 3 TO 5 DEGREES FROM
LIKELY HIGH TEMPERATURES DUE TO CLOUDS...WINDS AND SNOW COVER. THIS
ADJUSTMENT WAS MAINLY DONE OVER AREAS WHERE TWO OR MORE INCHES WERE
EXPECTED IN THE STORM TOTAL SNOWFALL GRIDDED FORECAST ACROSS THE WFO
PAH FORECAST AREA.
BY FRIDAY AFTERNOON...BOTH 12Z ECMWF AND GFS DETERMINISTIC MODEL
GUIDANCE INDICATE SOME ENHANCEMENT OF THE SHORTWAVE TROUGH MOVING
INTO THE WFO PAH FORECAST AREA IN THE SOUTHWESTERLY FLOW BEHIND THE
AFOREMENTIONED SHORTWAVE RIDGE. THE LIFT ASSOCIATED WITH THIS
FEATURE...COMBINED WITH A RESURGENCE OF CANADIAN POLAR AIR /AS WELL
AS ANY ANTECEDENT SNOW COVER/ SHOULD FORCE THE DEVELOPMENT OF LIGHT
WINTRY MIX LATE FRIDAY NIGHT. WITH THIS IN MIND...ATTEMPTED TO LIMIT
AN MEASURABLE SNOW/SLEET POTENTIAL WHERE THERE WAS NOT A MIX WITH
RAIN. AN INITIAL STAB AT SNOW/SLEET AMOUNTS WOULD LEAD TO AMOUNTS
LESS THAN ONE INCH OVER SOUTHEAST MO...SOUTHERN IL....SOUTHWEST IN
AND WESTERN KY ALONG THE OHIO RIVER. SHOULD THE COLDER AIR FILTER IN
FASTER...MAXIMUM AMOUNTS MAY BE CLOSER TO 1.5 INCHES.
SINCE THIS WEATHER SYSTEM LOOKS FOCUSED WITH MORE ISENTROPIC
LIFT...LEFT THE PRECIPITATION ON THE LIGHTER SIDE IN TERMS OF
INTENSITY AND SHORTER IN OVERALL DURATION OF MEASURABLE
PRECIPITATION.
BEYOND SATURDAY...RIDGING ALOFT WILL BUILD BACK INTO THE AREA WITH
SURFACE HIGH PRESSURE AT THE SURFACE. THIS SCENARIO...WITH ANY
ANTECEDENT SNOW COVER...WILL LEAD TOWARD SLIGHTLY COOLER
TEMPERATURES THAN NORMAL OVER SOUTHERN ILLINOIS AND SOUTHWEST
INDIANA THROUGH NEXT TUESDAY.
THERE IS SOME DIFFERENCE IN TIMING OF THE NEXT SOUTHWEST LOW MOVING
TOWARD THE AREA NEXT TUESDAY/WEDNESDAY...WITH THE ECMWF BEING COOLER
AND FASTER AND THE GFS SLOWER AND WARMER. FOR NOW...WILL KEEP THINGS
DRY THROUGH THE REMAINDER OF THIS FORECAST PACKAGE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1153 PM CST TUE DEC 25 2012
MVFR CIGS WILL DROP TO IFR AND OCCASIONALLY LIFR AS A WINTRY MIX
OF PRECIP CONTINUES ACROSS THE TAF SITES. PRECIP WILL BE A
SLEET/SNOW MIX CHANGING TO ALL SNOW OVERNIGHT...WITH IFR/LIFR
VSBYS ASSOCIATED WITH PRECIP. WINDY CONDITIONS EXPECTED WITH NE
WINDS AT 15-25 KTS WITH 35-45 KT GUSTS. CONDITIONS WILL GRADUALLY
IMPROVE TO MVFR FROM WEST TO EAST AFTER 14Z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR ILZ075>078-080>089-
092-093.
BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR ILZ090-091-094.
MO...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR MOZ076-086-087-100-
107>112-114.
IN...BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR INZ081-082-085>088.
KY...WINTER WEATHER ADVISORY FROM 6 AM TO NOON CST WEDNESDAY FOR
KYZ012-017-021-022.
BLIZZARD WARNING UNTIL NOON CST WEDNESDAY FOR KYZ001>011-013>016-
018>020.
&&
$$
SHORT TERM...MY
LONG TERM....SMITH
AVIATION...RST
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1213 AM CST WED DEC 26 2012
.UPDATE...
ISSUED AT 838 PM CST TUE DEC 25 2012
00Z NAM IS IN AND IT`S NOT LOOKING TOO GOOD FOR ACCUMULATING SNOW
MUCH NORTH OF OUR CURRENT WARNING. THE GRADIENT WE HAVE IN OUR
SNOWFALL FORECAST STILL LOOKS LIKE IT`S IN JUST ABOUT THE RIGHT
PLACE...BUT AMOUNTS ARE LOOKING A BIT TOO HIGH IF YOU TAKE THE QPF
VERBATIM. SINCE THE NAM IS THE ONLY NEW PIECE OF 00Z GUIDANCE
WE`VE GOT AT THIS TIME (ASIDE FROM THE RUC)...I`M NOT FEELING
PARTICULARLY BRAVE ABOUT CUTTING SNOWFALL AMOUNTS. THIS IS
ESPECIALLY TRUE SINCE THE RUC REALLY RAMPS UP VERTICAL MOTION JUST
SOUTH OF THE STL METRO OVER THE NEXT 2-4 HOURS. THIS MAY BE IN
RESPONSE TO A BACK-BUILDING JET STREAK OVER THE GREAT LAKES. THE
NAM SHOWS THIS TOO...BUT TO A LESSER EXTENT AND THE QPF LOOKS TO
BE MORE DRIVEN BY ISENTROPIC LIFT AND FRONTOGENESIS FURTHER SOUTH
ACROSS SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS. FOR NOW...WILL
LET CURRENT HEADLINES/SNOW AMOUNTS RIDE.
CARNEY
&&
.SHORT TERM...
ISSUED AT 335 PM CST TUE DEC 25 2012
(TONIGHT AND WEDNESDAY)
THE LATEST WATER VAPOR IMAGERY AND WIND PROFILERS/VWPS SHOW THE
UPPER LOW IS NOW LOCATED IN NW TX INVOF OF KTYR. THE STRONGEST
WINDS APPEAR TO BE ENTERING THE BASE OF THE TROF. THIS WOULD
SUGGEST THERE WILL BE CONTINUED EASTWARD MOTION INTO THE EVENING.
THE MODELS ARE REASONABLY WELL CLUSTED WITH THE H5 AND H85 LOW
CENTERS AND SEEM TO BE DOING A GOOD JOB. THE UPPER LOW SHOULD
BOTTOM OUT INVOF OF THE AR/LA BORDER BETWEEN 00-03Z AND THEN TAKE
ITS NEWD TURN EJECTING INTO THE WRN TN VALLEY OVERNIGHT AND INTO
THE OH VALLEY ON WEDNESDAY. DESPITE THE GOOD AGREEMENT IN THE MASS
FIELDS...THERE CONTINUE TO BE VARIANCES IN THE MODEL QPFS...ESPECIALLY
THE NRN EXTENT. THE NEW FORECAST IS BASICALLY A MULTI-MODEL BLEND
ON THE NRN FRINGE INCLUDING THE LATEST RUC.
SNOW IS GRADUALLY SPREADING NWD ACROSS AR ATTM AND WILL BE ENCOUNTERING
RELATIVELY DRIER NELY FLOW. THIS MAY INITIALLY SLOW THE PROGRESSES
BUT AS THE LOW MOVES INTO THE LOWER MS VALLEY THIS EVENING AND
THEN MAKES ITS NEWD TURN...THE LARGE SCALE ASCENT WILL OVERSPREAD
SE MO AND SRN IL MID-LATE EVENING AND SPREAD NEWD INTO SW IL
OVERNIGHT. FOLLOWING GOREE/YOUNKIN TECHNIQUES AND A MORE RECENT
HEAVY SNOW SYNOPTIC CLIMO BY GOSSELIN...THE HEAVIEST SNOW BAND
SHOULD BE SOUTH OF THE CWA ACROSS FAR SE MO AND SRN IL. THE
HEAVIEST SNOW WITHIN THE CWA STILL LOOKS LIKE IT WILL BE ON THE SE
FRINGE...WHERE THERE WILL ROUGHLY BE A PERIOD OF 6-8 HOURS OF
SNOW...MODERATE TO HEAVY AT TIMES. THE HIGHEST AMOUNTS WILL BE
SOUTH OF A LINE FROM CENTERVILLE TO FARMINGTON TO SPARTA TO SALEM
IN THE 5-6 INCH RANGE. I HAVE UPGRADED THE ADVISORY TO A WINTER
STORM WARNING GIVEN THESE SNOWFALL AMOUNTS AND THE STRONG AND
GUSTY NORTH/NORTHWEST WINDS OF 25-35 MPH PRODUCING BLOWING AND
DRIFTING SNOW. AN ADVISORY WILL ROUGHLY SPAN THE NRN FRINGE OF THE
WARNING. ST LOUIS WILL BE IN THE GRADIENT OF MEASURABLE SNOWFALL
AND THE WESTERN SUBURBS MAY SEE LITTLE TO NOTHING...WITH AMOUNTS
OF 1-2 INCHES IN THE SE IL SUBURBS. THE EVENT SHOULD WIND DOWN BY
MID-LATE MORNING ACROSS SW/SC IL. HOPEFULLY THERE WILL BE NO
SURPRISES TONIGHT.
GLASS
&&
.LONG TERM...
ISSUED AT 314 PM CST TUE DEC 25 2012
(THURSDAY THROUGH TUESDAY)
THERE STILL LOOKS TO BE A CHANCE OF SNOW MAINLY FRIDAY NIGHT
ALTHOUGH THE PROBABILITY LOOKS LESS THAN ADVERTISED 2 DAYS AGO.
OVERALL THE PATTERN LOOKS SEASONABLY COLD.
GLASS
&&
.AVIATION...
ISSUED AT 1210 AM CST WED DEC 26 2012
NO CHANGE WITH THE LATEST GUIDANCE WITH NWRN EDGE OF ACCUMULATING
SNOWFALL SETTING UP JUST TO THE SW OF STL METRO AREA...WITH WHAT
IS EXPECTED TO BE A FAIRLY WIDESPREAD AREA OF LIGHT FLURRIES OVER
THE STL METRO AREA FOR OVERNIGHT. STILL FAVOR A MORE PESSIMISTIC
TAF FOR KCPS WITH IFR VSBYS...BUT BELIEVE NOW THAT PERSISTENT LIFT
OVER THE STL METRO AREA SHOULD RESULT IN 2-3HRS OF IFR CIGS AS
WELL. ELSEWHERE TO THE NW OF THE STL METRO AREA...LOOK FOR VFR
CIGS LOWERING TO MVFR OVERNIGHT THANKS TO AFOREMENTIONED LIFT.
STRONG AND GUSTY N SFC WNDS WILL PERSIST THRU OVERNIGHT.
SPECIFICS FOR KSTL...EXPECT JUST FLURRIES OVERNIGHT BUT MAY GET
SOMETHING A BIT HEAVIER FOR AN HOUR OR TWO OVERNIGHT BEFORE
EVERYTHING WINDS DOWN AROUND SUNRISE. SHOULD EVEN SEE A BRIEF
PERIOD OF IFR CIGS THANKS TO PERSISTENT AND DEEPENING LIFT
OVERHEAD WHICH HAS CAUSED CIGS TO LOWER THRU THE EVENING. ONCE THE
SYSTEM PULLS AWAY LATER ON WEDNESDAY MORNING...LOOK FOR PERSISTENT
MVFR CIGS FOR MUCH OF THE REST OF THE PERIOD WITH SFC WNDS GUSTING
TO 25KTS OR SO...DIMINISHING TO LESS THAN 10KTS WEDNESDAY NIGHT.
SOME QUESTION ON HOW WELL CIGS WILL BE ABLE TO HANG IN THERE
WEDNESDAY NIGHT BUT FOR NOW...IN THE ABSENCE OF STRONG EVIDENCE...
WENT WITH A PERSISTENCE FCST FOR NOW.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 6 AM CST WEDNESDAY FOR MADISON MO-ST.
FRANCOIS MO-STE. GENEVIEVE MO.
WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR IRON MO-
REYNOLDS MO-WASHINGTON MO.
IL...WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR BOND IL-
CLINTON IL-FAYETTE IL-MONROE IL-ST. CLAIR IL.
WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR MARION IL-
RANDOLPH IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
305 AM CST WED DEC 26 2012
.DISCUSSION...
SNOW AMOUNTS THURSDAY/THURSDAY NIGHT ARE THE MAIN FORECAST FOCUS
AS WEST COAST SYSTEM PROVIDES A PROLONGED PERIOD OF WEAK TO
MODERATE LIFT ACROSS THE AREA. HOW FAR SOUTH WILL THESE MODEST
SNOW AMOUNTS POTENTIALLY EXTEND IS ALSO AN ISSUE. AFTER THIS
SYSTEM DEPARTS...REMAINDER OF FORECAST WILL BE DRY WITH MINOR
TEMPERATURE FLUCTUATIONS.
EARLY MORNING SATELLITE IMAGERY SHOWED FORECAST AREA IN BETWEEN
NRN PLAINS TROUGH/MS VALLEY CLOSED LOW AND APPROACHING BROAD WEST
COAST TROUGH. THUS AFTER A MAINLY EARLY DAY PERIOD OF MID
CLOUDINESS NRN ZONES ALONG WITH PSBL FLURRIES...PTLY/MOSTLY SUNNY
START TO DAY SHOULD BE FOLLOWED BY INCREASING CLOUDS LATER AS
WEST COAST TROUGH SPREADS SOME HIGH CLOUDS AND THEN THICKENING
WARM ADVECTION MID LEVEL CLOUDS TOWARD AND ACROSS THE FORECAST
AREA. BOOSTED SOME TEMPERATURES THIS AFTN...ESPECIALLY NWRN ZONES
WHERE WARM ADVECTION...LATE MORNING/EARLY AFTN SUN AND LESSER
SNOW COVER SUPPORT RAP SFC TEMP FORECAST OF NEAR OR ABOVE 20 F.
WEST COAST SYSTEM HAD DECENT 100+ M HGT FALLS AT H5 FM CNTRL CA
INTO WA LAST EVENING...AND AS IT MOVES ACROSS THE ROCKIES...00Z
NAM/GFS/ECMWF WERE SIMILAR IN CLOSING OFF H7 LOW AND PLACING INTO
CNTRL NEBR JUST WEST OF WCNTRL ZONES AT 00Z FRIDAY. LOW THEN
FORECAST TO SLOWLY LIFT ENE ACROSS NERN NEBR THU NGT ALTHOUGH
MODELS BEGIN DIVERGING ON AMOUNT OF ENERGY/LIFT LAGS BACK. BROAD
WARM ADVECTION...DEPICTED NICELY ON 285K ISENTROPIC SURFACES...SHOULD
BEGIN THICKENING CLOUDS OVER AREA LATE TONIGHT INTO MIDDAY
THURSDAY FOLLOWED BY INCREASING SNOW AREA. APPEARS A GENERAL
0.10-0.20 QPF TOTAL GENERATED BY SREF/NAM/GFS/ECMWF IS
ACCEPTABLE...ALTHOUGH IT WAS NOTED CANADIAN WAS ABOUT DOUBLE THAT
WHICH WOULD POSE MORE PROBLEMS SINCE WITH DEEP COLD AIRMASS IN
PLACE...SNOW TO LIQUID RATIOS COULD BE IN UPPER TEENS TO AROUND 20-1.
QUESTION BECOMES HOW FAR SOUTH WILL THE HIGHER QPF TOTALS EXTEND.
WOULD THINK THEY WOULD BE MOSTLY ALONG AND NORTH OF H7 TRACK WHICH
WOULD PLACE THEM MOSTLY NORTH OF HIGHWAY 30. HOWEVER...STEEP H7-H5
LAPSE RATES WERE NOTED SWRN ZONES THU AFTN AND ALONG KS/MO BORDERS
THU NGT WHICH COULD AID IN SOME SORT OF CONVECTIVE PCPN BANDS
SOUTHERN ZONES. THIS FORECAST WILL INCLUDE AMOUNTS AROUND 2
INCHES NEAR HIGHWAY 30 WITH 3-4 INCHES NORTH OF THERE AND AMOUNTS
LOWERING TO LESS THAN AN INCH SOUTH OF LINCOLN-SWRN IA. NO
HEADLINES YET AS WINDS EXPECTED TO BE MODEST AND THESE TOTALS
EXTEND AT LEAST OVER AN 18 HR PD. INCREASING CLOUDS SHOULD HOLD
TEMPS UP TONIGHT WITH LATE EVENING LOW PROBABLE MOST AREAS...BUT
CLOUDS AND SNOW COULD LIMIT WARMING NRN ZONES SOME DEGREE
THURSDAY.
WITH POTENTIALLY SLOWER DEPARTURE OF UPPER TROUGH...INCREASED SNOW
CHANCES NERN ZONES THU NGT AND EVEN FRIDAY MORNING FAR EAST.
TEMPERATURE PROFILE IN ANY LINGERING MOISTURE+PERSISTENT WEAK
LIFT PER NAM COULD KEEP LIGHT SNOW OR FLURRIES GOING WELL INTO
FRIDAY AND THUS FLURRIES WERE EXTENDED OVER NERN 1/3RD
EVEN FRI AFTN. DELAYED CLEARING SHOULD KEEP DIURNAL TEMPERATURE
RANGE SMALLER AND READINGS WERE ADJUSTED FOR SUCH.
AFTER THAT...AS MENTIONED ABOVE...FORECAST WAS KEPT DRY.
MODERATING TEMPERATURES EXPECTED SATURDAY INTO SUNDAY AS UPPER
RIDGING OCCURS BEFORE FLOW FLATTENS AS NRN STREAM TROUGH
APPROACHES. COULD CONCEIVABLY WARM NICELY SOME AREAS ON SUNDAY
AHEAD OF TROUGH...BUT HELD BACK BY SNOW COVER. NONETHELESS...DID
BOOST READINGS A LITTLE...THE MOST ON SUNDAY ACROSS THE SW. HIGHS
WERE KEPT IN CONSERVATIVE 20S MON/NEW YEARS DAY...BUT PER
ECMWF...ARCTIC AIR MAY REMAIN BOTTLED UP FARTHER NORTH THAN
THE FORECAST AREA.
CHERMOK
&&
.AVIATION...
06Z TAFS FOR KOFK...KOMA AND KLNK.
VFR CONDITIONS WILL PREVAIL THRU THE 24HR FCST PD.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS SPOKANE WA
949 PM PST Tue Dec 25 2012
.SYNOPSIS...
Another storm system will spread steady light snow across the
region tonight, before dissipating into snow showers through
Wednesday night. Drier, colder conditions arrive for the end of
the work week. While minor amounts of snow can be expected from
time to time...there are no major storm systems expected for the
next week.
&&
.DISCUSSION...
Update: The winter weather advisories for the Wenatchee area and
Waterville Plateau, and the East Slopes of the North Washington
Cascades have been cancelled. Water vapor satellite imagery shows
a stretching frontal band over Eastern Washington as an upper
trough along the Washington and Oregon coast continues to dive
south. Latest 00z models as well as the HRRR shows just occasional
rounds of very light snow over North Central Washington tonight
and thus the threat for additional snow accumulations of over an
inch has ended. As the stretching frontal band continued to move
east into North Idaho tonight light snow will develop in places
like Sandpoint, Coeur D`Alene, and Kellogg but accumulations will be very
light. For the Lewiston area southwest downslope winds off the
Blues will limit precipitation chances so pops were lowered in
this area. With abundant low level moisture and high dew points in
the upper 20s and lower 30s tonight stratus will be widespread
which will limit temperature falls. Lows were increased slightly
for most of the area. JW
&&
.AVIATION...
06Z TAFS: An area of light snow associated with a weak front over
Northeast Washington and North Idaho will continue to move east and
weaken through 09. Meanwhile another wave over Central Oregon
will move northeast towards KPUW/KLWS overnight and Wednesday
morning. This weak feature in combination with a wind reversal to
more favorable low level upslope west-northwest direction will
likely bring lowering CIGS at KPUW and KLWS with an increasing
chance for -SN especially KPUW. Elsewhere a deep and saturated
boundary layer will promote a mix of IFR and MVFR stratus across the
entire region through 6z Thursday. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 26 31 25 33 24 33 / 80 60 40 20 10 10
Coeur d`Alene 26 32 27 34 25 35 / 60 60 40 20 10 10
Pullman 29 33 29 34 27 34 / 80 60 60 40 20 10
Lewiston 33 39 31 41 30 41 / 50 50 50 30 20 10
Colville 26 31 25 33 25 34 / 50 50 30 20 10 10
Sandpoint 25 30 27 33 26 32 / 60 50 30 30 10 10
Kellogg 24 32 26 30 24 31 / 70 70 50 40 20 10
Moses Lake 26 32 25 35 25 37 / 80 40 20 10 0 10
Wenatchee 25 31 24 34 25 35 / 60 40 20 10 0 10
Omak 23 29 20 29 22 31 / 60 40 20 10 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
808 PM PST Tue Dec 25 2012
.SYNOPSIS...
Another storm system will spread steady light snow across the
region tonight, before dissipating into snow showers through
Wednesday night. Drier, colder conditions arrive for the end of
the work week. While minor amounts of snow can be expected from
time to time...there are no major storm systems expected for the
next week.
&&
.DISCUSSION...
Update: The winter weather advisories for the Wenatchee area and
Waterville Plateau, and the East Slopes of the North Washington
Cascades have been cancelled. Water vapor satellite imagery shows
a stretching frontal band over Eastern Washington as an upper
trough along the Washington and Oregon coast continues to dive
south. Latest 00z models as well as the HRRR shows just occasional
rounds of very light snow over North Central Washington tonight
and thus the threat for additional snow accumulations of over an
inch has ended. As the stretching frontal band continued to move
east into North Idaho tonight light snow will develop in places
like Sandpoint, Coeur D`Alene, and Kellogg but accumulations will be very
light. For the Lewiston area southwest downslope winds off the
Blues will limit precipitation chances so pops were lowered in
this area. With abundant low level moisture and high dew points in
the upper 20s and lower 30s tonight stratus will be widespread
which will limit temperature falls. Lows were increased slightly
for most of the area. JW
&&
.AVIATION...
00Z TAFS: An occluded front over the Cascades at 00Z Wednesday
will track through eastern Washington tonight. A 4 to 6 hour
period of SN with likely IFR ceilings and Vis will occur at most
TAF sites as this front approaches and passes. With a light
surface pressure gradient...post frontal FG and IFR Stratus
ceilings will be probable at the KEAT...KMWH and KGEG area TAF
sites through 18Z Wednesday. KLWS and KPUW will experience periods
of snow tonight...but should display significantly improving
conditions after FROPA. After 18Z Wednesday and through 00Z
Thursday...moist boundary layer air mass will promote continued
widespread MVFR ceilings at most TAF sites./MJF
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 26 31 25 33 24 33 / 80 60 40 20 10 10
Coeur d`Alene 26 32 27 34 25 35 / 60 60 40 20 10 10
Pullman 29 33 29 34 27 34 / 80 60 60 40 20 10
Lewiston 33 39 31 41 30 41 / 50 50 50 30 20 10
Colville 26 31 25 33 25 34 / 50 50 30 20 10 10
Sandpoint 25 30 27 33 26 32 / 60 50 30 30 10 10
Kellogg 24 32 26 30 24 31 / 70 70 50 40 20 10
Moses Lake 26 32 25 35 25 37 / 80 40 20 10 0 10
Wenatchee 25 31 24 34 25 35 / 60 40 20 10 0 10
Omak 23 29 20 29 22 31 / 60 40 20 10 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
501 AM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM BRINGS MIXED PRECIPITATION TODAY INTO
THURSDAY. ANOTHER LOW PRESSURE SATURDAY...WITH MORE MIXED
PRECIPITATION...CHANGING TO SNOW FOR THE END OF THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
ADJUSTED HOURLY TEMPERATURES AND DEWPOINTS TO MATCH LATEST SFC OBS
AND THEN USED THE RUC13 THROUGH 8 AM.
UPDATED WIND AND WINDS GUSTS PER LATEST SFC OBS AND RADAR
SIGNATURE SHOWING GUST UP TO 20 KNOTS AT HTS AND BKW. WINDS COULD
INCREASE OVERNIGHT EXCEPT AT PROTECTED VALLEYS...BUT MORE SO ON
WEDNESDAY GUSTING AROUND 30 KNOTS ESPECIALLY HIGHER ELEVATIONS.
PREVIOUS DISCUSSION BELOW...
900 PM UPDATE... MODEL SOUNDINGS SEEM TO HAMMER THE EASTERN SLOPES
OF THE CENTRAL APPALACHIANS WITH ICE...SO HAVE EXPANDED ADVISORIES
DOWN THROUGH NICHOLAS...FAYETTE AND RALEIGH COUNTIES...MAINLY FOR
THE EASTERN SLOPES THEREOF. FROZEN QPF COULD ACTUALLY EXCEED 0.25
INCH BUT WITH UPDATED TEMPERATURES /WRFARW AND NAM12/ RIGHT AT
FREEZING IN THAT AREA...THINKING ADVISORIES OUGHT TO SUFFICE. HAVE
ADVISORIES GOING TO 18Z LIKE THOSE FURTHER N BUT HAVE DELAYED
ONSET OF ALL WARNINGS AND ADVISORIES UNTIL 06Z OVERNIGHT. ALSO
EXTENDED THE PERRY COUNTY WINTER STORM WARNING UNTIL 00Z AS
TEMPERATURES THERE MAY NEVER GET ABOVE FREEZING.
ALSO DELAYED ONSET OF POPS A BIT PER CURRENT TRENDS AND ALL ASPECTS
OF THIS WINTER FORECAST APPEAR TO BE IN GOOD COORD.
700 PM UPDATE...
NO SIGNIFICANT CHANGES NEEDED AT THIS TIME.
PREV DISCN...
GFS STILL THE PREFERRED MODEL OVER THE NAM AT THIS POINT...WHICH IS
ALSO THE WARMER OF THE TWO MODELS...ESPECIALLY OFF THE SURFACE. THE
KEY TO THE FORECAST THIS AFTERNOON IS THE OVERRUNNING AHEAD OF THE
SYSTEM...AND THE WARM LAYER ALOFT OVER SUB FREEZING SURFACE
TEMPERATURES WHICH WILL CREATE ICY CONDITIONS. GFS IS AGGRESSIVE
WITH THIS...AND WILL SEE AN EXTENDED PERIOD OF FREEZING RAIN WITH
SOME ICE PELLETS FOR THE NORTHERN TIER OF COUNTIES IN THE CWA...AND
TO MORE OF AN EXTENT WITH THE COLD AIR DAMMING FOR RANDOLPH AND
POCAHONTAS COUNTIES ON THE EASTERN SLOPES. THIS WINTRY MIX OF
PRECIPITATION WILL BEGIN TONIGHT...TURNING TO MOSTLY RAIN BY
WEDNESDAY EVENING...ESPECIALLY FOR THE LOWLAND AREAS. THIS MAY NOT
HOLD TRUE FOR THE AFOREMENTIONED NORTHEAST MOUNTAINS AND PERRY AND
MORGAN COUNTIES IN SOUTHEAST OHIO WHERE THE COLD AIR AT THE SURFACE
HAS A BETTER CHANCE OF HOLDING IN PLACE AS THE FLOW BECOMES MORE
NORTHERLY. COLD AIR TO COLLAPSE AS THE COASTAL SURFACE LOW BECOMES
THE DOMINANT PLAYER...WHICH WILL ALSO AID IN THE PROCESS OVER
SOUTHEAST OHIO.
SNOW IS POSSIBLE ON THE NORTHEAST AND NORTHWEST FRINGES OF THE CWA
WITH SOME ACCUMULATIONS POSSIBLE AND SHOULD NOT BE OVERLOOKED IN
THIS FORECAST. MAY SEE A COATING TO A COUPLE OF INCHES PRIOR TO
ONSET OF THE FREEZING RAIN ACROSS THE NORTH...AND NEAR THE END OF
THE NEAR TERM LATE WEDNESDAY IN SOUTHEAST OHIO.
STRONG LOW LEVEL JET LIKELY TO PRODUCE VERY STRONG SOUTHEAST WINDS
OVER THE MOUNTAINS LATE TONIGHT AND WEDNESDAY. RIDGES AND MOUNTAIN
TOPS WILL BE MOST LIKELY TO EXPERIENCE THE STRONG WINDS IN THE
UPGLIDING NATURE OF THE FLOW AS SEEN ON ISENTROPIC SURFACES.
INTERSTATE 77 LIKELY TO BE EXPOSED TO THESE EFFECTS JUST NORTH OF
FLAT TOP IN RALEIGH COUNTY.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AT THE OUTSET OF THE PERIOD NWP GUIDANCE IN GOOD AGREEMENT WITH
STRONG LOW PRESSURE SYSTEM NEARLY STACKED AND LOCATED ROUGHLY OFF
THE DELMARVA/NJ COASTLINE AND MOVING NORTHEASTWARD UP THE COAST
AND AWAY FROM THE FORECAST AREA...TAKING MUCH OF THE DEEP LAYER
MOISTURE WITH IT AND LARGE SCALE FORCING FOR SUBSIDENCE
OVERSPREADING THE AREA. OVERALL NOT MUCH CHANGE WITH REGARD TO
EXPECTED POPS IN A GENERAL SENSE FOR THURSDAY BUT DID ELECT TO
KEEP SLIGHT CHANCE POPS GOING JUST A BIT LONGER THURSDAY MORNING
ACROSS NW ZONES WITH POINT SOUNDINGS AT LOCATIONS SUCH AS PKB
STILL INDICATING ROUGHLY 2KFT OF LLVL MOISTURE IN PLACE AT 18Z
WITH SOME WEAK WARM ADVECTION NOTED AT 850MB AND BELOW...CAN/T
COMPLETELY RULE OUT A LOCATION SQUEEZING OUT A HUNDREDTH THOUGH A
TRACE OR HEAVY MIST IS CERTAINLY MORE LIKELY. ALSO ELECTED TO
KEEP LIKELY POPS GOING ACROSS THE EASTERN HIGH TERRAIN THROUGH 00Z
FRI WITH TRAPPED LLVL MOISTURE IN PLACE WITH AN INCREASING
TRAJECTORY OF LLVL FLOW OFF OF LAKE ERIE AS THE DAY PROGRESSES.
SOME CONCERN EXISTS WITH PRECIP TYPE...ESPECIALLY DURING THE
MORNING HOURS. AS PREV FCST MENTIONED...THERE IS THE POTENTIAL FOR
SOME FREEZING DRIZZLE ACROSS THE AREA AS THE COLUMN DRIES FROM
ABOVE. BOTH THE LATEST NAM AND GFS DRAG A STOUT DRY LAYER AT -10C
ACROSS THE AREA FROM SW TO NE ROUGHLY BTWN 09Z-15Z. MEANWHILE...AGAIN
BOTH MODELS AT CRW SHOW ROUGHLY 4KFT OF LLVL MOISTURE DEPTH IN
PLACE AT 12Z THU BELOW -10C WITH SFC TEMPS PROGGED TO BE AROUND
30F GIVE OR TAKE. WITH THIS IN MIND...WILL ALLOW SNOW TO STILL BE
PRIMARY PRECIP TYPE BUT ALSO INCLUDE A PATCHY FREEZING DRIZZLE
MENTION AND LET THE DAYSHIFT REEVALUATE. AND FINALLY...ITS
POSSIBLE A WIND ADV MAY BE NEEDED FOR THE EASTERN MOUNTAIN
COUNTIES OF RANDOLPH AND POCAHONTAS THURSDAY WITH WINDS SPEEDS
RUNNING AROUND THE 25-30KT RANGE. WILL DEFER ANY WIND HIGHLIGHT AT
THIS TIME TO THE DAY SHIFT OR TONIGHT/S NIGHT SHIFT WITH THE
MULTITUDE OF ONGOING WINTER WX HIGHLIGHTS CURRENTLY IN PLACE.
OVERNIGHT THU NIGHT/FRI MORNING THE SYSTEM CONTINUES TO PULL AWAY
FROM AREA WITH S/W RIDGING BUILDING OVERHEAD ALONG WITH SFC HIGH
PRESSURE. LLVL WIND TRAJECTORY INTO THE NE HIGH TERRAIN GRADUALLY
BACKS TOWARD THE WEST AND THUS THE FLOW OFF THE GREAT LAKES
WANES...AT WHICH TIME PRECIP IN THE NORTHEAST MOUNTAINS BEGINS TO
WIND DOWN. WINDS GO NEAR CALM THOUGH THERE IS SOME WARM ADVECTION
FROM THE SOUTHWEST AFTER 06Z. NONETHELESS...A CHILLY NIGHT IS IN
STORE PARTICULARLY IN SHELTERED VALLEY LOCATIONS AS WELL AS FAR NW
ZONES WHERE FRESH SNOW COVER IS EXPECTED.
FRIDAY...GENERALLY PARTLY CLOUDY SKIES CAN BE EXPECTED AS SFC HIGH
PRESSURE MOVES OFF TO THE EAST AND FLOW ALOFT TURNS SOUTHWESTERLY.
INHERITED MAX TEMPS GENERALLY LOOK GOOD WITH JUST A FEW MINOR
TWEAKS. FRIDAY NIGHT AND SATURDAY MORNING THE NEXT SYSTEM QUICKLY
MOVES NORTHEASTWARD INTO THE AREA SPREADING RAIN AND SNOW FROM
SOUTHWEST TO NORTHEAST MAINLY AFTER 06Z SAT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
USED A BLEND OF THE ECMWF AND ECMWF ENSEMBLE MEAN FOR THE WEEKEND
SYSTEM. THIS WOULD HAVE A LOW PASS SOUTH OF THE REGION...PROVIDING A
LIGHT SNOW EVENT FOR SATURDAY WITH SOME MIXED PRECIPITATION POSSIBLE
IN THE LOW LANDS. BY SUNDAY...COLDER AIR WOULD MOVE IN FOR AN
UPSLOPE EVENT.
FOR EARLY NEXT WEEK...RELIED ON A GEFS AND ECMWF ENSEMBLE
MEAN...BUT NOT HIGH CONFIDENCE. THIS WOULD BRING A WEAK WINTRY
SYSTEM THROUGH MONDAY NIGHT/TUESDAY.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
STARTING WITH VFR CONDITIONS AT THE BEGINNING OF THE PERIOD ALL
SITES.
RADAR IMAGES SHOW THE LEADING EDGE OF PCPN REACHING THE
EXTREME SOUTHERN WV BY 05Z. EXPECT GUSTY WINDS INCREASING OVER
HIGHER ELEVATIONS AND EXPOSED SITES OVERNIGHT. EKN MAY REMAIN CALM
OR LIGHT AND VARIABLE FLOW THROUGH AT LEAST 13Z.
TRICKY FORECAST IN TERMS OF PCPN TYPE. DUAL POL MELTING SIGNATURE
IS EVIDENT IN THE LEADING EDGE OF PCPN SOUTH OF CRW AND HTS ABOUT
3K FEET AGL. ATTM...A RELATIVELY WARMER AIR MASS WILL ADVECT FROM
THE SOUTH INTO A MUCH COLDER AIR NORTH ALONG AND NORTH OF A LINE
FROM HTS...CRW...AND BKW. THEREFORE...EXPECT MOST PCPN TO BE
LIQUID REACHING HTS...CRW AROUND 08Z. RAIN MIXED WITH ICE PELLETS
AT BKW AROUND 08Z...TRANSITIONING TO FREEZING RAIN AROUND 10Z
UNDER MVFR CONDITIONS.
EXTENDED PERIOD OF FREEZING RAIN AND ICE AT BKW FROM 10-18Z...AND
EKN FROM 10-20Z. A FEW HOURS ALSO AT CKB ARE EXPECTED STARTING
AROUND 13-19Z. PKB MAY SEE BRIEF ICE AS WELL...BUT MORE LIKELY TO
BE RAIN MIXED WITH ICE PELLETS AROUND 22Z BEFORE TRANSITIONING TO
ALL SNOW BY 04Z THURSDAY.
WIDESPREAD MVFR...AND IFR POSSIBLE AT TIMES LATE OVERNIGHT AND
WEDNESDAY. HOWEVER...LOWLANDS ADJACENT TO THE WESTERN SLOPES SHOULD
EXPERIENCE VFR CEILINGS IN DOWNSLOPING SOUTHEAST FLOW WEDNESDAY.
LOWER VISIBILITIES TO IFR/LIFR AT THE END OF THE PERIOD WITH AREAS
OF SNOW.
FLOW BECOMES STRONG SOUTHEAST LATE OVERNIGHT AND REMAIN SO WEDNESDAY EAST
OF THE OHIO RIVER...AND MODERATE NORTHEAST...ALONG AND WEST OF
THE OHIO RIVER DURING THESE TIMES.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF PRECIPITATION TYPE TRANSITION COULD
VARY. DURATION AND EXTENT OF ICE COULD VARY. DURATION AND EXTENT
OF LOWER CIGS AND VSBYS IN PRECIPITATION COULD ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE WED 12/26/12
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY H H M H M M M L M H H H
HTS CONSISTENCY H H H L L L L L L H M M
BKW CONSISTENCY L L L L L L L L L L L L
EKN CONSISTENCY L L L L L L L L L L L L
PKB CONSISTENCY H L L L L L L M M M M M
CKB CONSISTENCY H H L L L L L L L L L L
AFTER 12Z THURSDAY...
IFR POSSIBLE IN MIXED PRECIPITATION AND RAIN IN SE OHIO AND THE WV
MOUNTAINS WED NIGHT...AND IN SNOW SHOWERS THROUGHOUT THE AREA BUT
MORE SO IN THE MOUNTAINS LATE WEDNESDAY NIGHT INTO THURSDAY. IFR
POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE
MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
WVZ011-020-031-032-035>040.
ICE STORM WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ046-047.
OH...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
OHZ067-075-076.
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR OHZ066.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...ARJ/50
NEAR TERM...ARJ
SHORT TERM...50
LONG TERM...RPY
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1247 AM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM BRINGS MIXED PRECIPITATION FROM LATE
TONIGHT INTO THURSDAY. ANOTHER LOW PRESSURE SATURDAY...WITH MORE
MIXED PRECIPITATION...CHANGING TO SNOW FOR THE END OF THE WEEKEND.
&&
.NEAR TERM /UNTIL 10 AM THIS MORNING/...
ADJUSTED HOURLY TEMPERATURES AND DEWPOINTS TO MATCH LATEST SFC OBS
AND THEN USED THE RUC13 THROUGH 8 AM.
UPDATED WIND AND WINDS GUSTS PER LATEST SFC OBS AND RADAR
SIGNATURE SHOWING GUST UP TO 20 KNOTS AT HTS AND BKW. WINDS COULD
INCREASE OVERNIGHT EXCEPT AT PROTECTED VALLEYS...BUT MORE SO ON
WEDNESDAY GUSTING AROUND 30 KNOTS ESPECIALLY HIGHER ELEVATIONS.
PREVIOUS DISCUSSION BELOW...
900 PM UPDATE... MODEL SOUNDINGS SEEM TO HAMMER THE EASTERN SLOPES
OF THE CENTRAL APPALACHIANS WITH ICE...SO HAVE EXPANDED ADVISORIES
DOWN THROUGH NICHOLAS...FAYETTE AND RALEIGH COUNTIES...MAINLY FOR
THE EASTERN SLOPES THEREOF. FROZEN QPF COULD ACTUALLY EXCEED 0.25
INCH BUT WITH UPDATED TEMPERATURES /WRFARW AND NAM12/ RIGHT AT
FREEZING IN THAT AREA...THINKING ADVISORIES OUGHT TO SUFFICE. HAVE
ADVISORIES GOING TO 18Z LIKE THOSE FURTHER N BUT HAVE DELAYED
ONSET OF ALL WARNINGS AND ADVISORIES UNTIL 06Z OVERNIGHT. ALSO
EXTENDED THE PERRY COUNTY WINTER STORM WARNING UNTIL 00Z AS
TEMPERATURES THERE MAY NEVER GET ABOVE FREEZING.
ALSO DELAYED ONSET OF POPS A BIT PER CURRENT TRENDS AND ALL ASPECTS
OF THIS WINTER FORECAST APPEAR TO BE IN GOOD COORD.
700 PM UPDATE...
NO SIGNIFICANT CHANGES NEEDED AT THIS TIME.
PREV DISCN...
GFS STILL THE PREFERRED MODEL OVER THE NAM AT THIS POINT...WHICH IS
ALSO THE WARMER OF THE TWO MODELS...ESPECIALLY OFF THE SURFACE. THE
KEY TO THE FORECAST THIS AFTERNOON IS THE OVERRUNNING AHEAD OF THE
SYSTEM...AND THE WARM LAYER ALOFT OVER SUB FREEZING SURFACE
TEMPERATURES WHICH WILL CREATE ICY CONDITIONS. GFS IS AGGRESSIVE
WITH THIS...AND WILL SEE AN EXTENDED PERIOD OF FREEZING RAIN WITH
SOME ICE PELLETS FOR THE NORTHERN TIER OF COUNTIES IN THE CWA...AND
TO MORE OF AN EXTENT WITH THE COLD AIR DAMMING FOR RANDOLPH AND
POCAHONTAS COUNTIES ON THE EASTERN SLOPES. THIS WINTRY MIX OF
PRECIPITATION WILL BEGIN TONIGHT...TURNING TO MOSTLY RAIN BY
WEDNESDAY EVENING...ESPECIALLY FOR THE LOWLAND AREAS. THIS MAY NOT
HOLD TRUE FOR THE AFOREMENTIONED NORTHEAST MOUNTAINS AND PERRY AND
MORGAN COUNTIES IN SOUTHEAST OHIO WHERE THE COLD AIR AT THE SURFACE
HAS A BETTER CHANCE OF HOLDING IN PLACE AS THE FLOW BECOMES MORE
NORTHERLY. COLD AIR TO COLLAPSE AS THE COASTAL SURFACE LOW BECOMES
THE DOMINANT PLAYER...WHICH WILL ALSO AID IN THE PROCESS OVER
SOUTHEAST OHIO.
SNOW IS POSSIBLE ON THE NORTHEAST AND NORTHWEST FRINGES OF THE CWA
WITH SOME ACCUMULATIONS POSSIBLE AND SHOULD NOT BE OVERLOOKED IN
THIS FORECAST. MAY SEE A COATING TO A COUPLE OF INCHES PRIOR TO
ONSET OF THE FREEZING RAIN ACROSS THE NORTH...AND NEAR THE END OF
THE NEAR TERM LATE WEDNESDAY IN SOUTHEAST OHIO.
STRONG LOW LEVEL JET LIKELY TO PRODUCE VERY STRONG SOUTHEAST WINDS
OVER THE MOUNTAINS LATE TONIGHT AND WEDNESDAY. RIDGES AND MOUNTAIN
TOPS WILL BE MOST LIKELY TO EXPERIENCE THE STRONG WINDS IN THE
UPGLIDING NATURE OF THE FLOW AS SEEN ON ISENTROPIC SURFACES.
INTERSTATE 77 LIKELY TO BE EXPOSED TO THESE EFFECTS JUST NORTH OF
FLAT TOP IN RALEIGH COUNTY.
&&
.SHORT TERM /10 AM THIS MORNING THROUGH FRIDAY/...
SHORT TERM COMMENCES WITH LOW PRESSURE SYSTEM PULLING OFF TO THE
EAST...WITH COLDER AIR FILTERING IN BEHIND IT. THIS WILL RESULT IN A
GRADUAL CHANGE OVER OF ANY MIXED PRECIPITATION TO SNOW WEDNESDAY
NIGHT. HOWEVER...AS THE LOW PULLS AWAY FROM THE AREA...IT TAKES MUCH
OF THE MOISTURE WITH IT...THEREBY LIMITING THE POTENTIAL FOR ANY
SIGNIFICANT SNOWFALL ACCUMULATIONS ACROSS THE AREA. BEST LOCATION
FOR ANY LIGHT SNOWFALL ACCUMULATIONS WILL BE IN THE NORTHERN
MOUNTAIN ZONES...IN THE UPSLOPE WNW FLOW ALOFT. COULD EVEN BE A
TRANSITION OVER TO DRIZZLE OR FREEZING DRIZZLE TOWARDS THE END OF
THE EVENT AS MUCH OF THE MOISTURE IN THE DENDRITE GROWTH ZONE IS
LOST WITH TIME. IN ADDITION TO ANY LINGERING WINTRY
PRECIPITATION...GUSTY WINDS WILL STILL CONTINUE TO LINGER ACROSS THE
HIGHER TERRAIN WEDNESDAY NIGHT FROM STRONG WINDS ALOFT.
HIGH PRESSURE WITH GRADUAL CLEARING CONDITIONS WILL THEN BEGIN TO
BUILD IN FOR FRIDAY NIGHT. DEPENDING ON THE AMOUNT OF CLEARING...AND
SNOW COVER...COULD BE A RATHER CHILLY NIGHT ON TAP...PARTICULARLY
ACROSS SOME OF THE SHELTERED MOUNTAIN VALLEYS.
THE HIGH PRESSURE WILL REMAIN IN CONTROL FOR
FRIDAY...HOWEVER...CLOUDS WILL BE ON THE INCREASE AGAIN FROM THE
WEST AS YET ANOTHER STORM SYSTEM APPROACHES.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
USED A BLEND OF THE ECMWF AND ECMWF ENSEMBLE MEAN FOR THE WEEKEND
SYSTEM. THIS WOULD HAVE A LOW PASS SOUTH OF THE REGION...PROVIDING A
LIGHT SNOW EVENT FOR SATURDAY WITH SOME MIXED PRECIPITATION POSSIBLE
IN THE LOW LANDS. BY SUNDAY...COLDER AIR WOULD MOVE IN FOR AN
UPSLOPE EVENT.
FOR EARLY NEXT WEEK...RELIED ON A GEFS AND ECMWF ENSEMBLE
MEAN...BUT NOT HIGH CONFIDENCE. THIS WOULD BRING A WEAK WINTRY
SYSTEM THROUGH MONDAY NIGHT/TUESDAY.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
STARTING WITH VFR CONDITIONS AT THE BEGINNING OF THE PERIOD ALL
SITES.
RADAR IMAGES SHOW THE LEADING EDGE OF PCPN REACHING THE
EXTREME SOUTHERN WV BY 05Z. EXPECT GUSTY WINDS INCREASING OVER
HIGHER ELEVATIONS AND EXPOSED SITES OVERNIGHT. EKN MAY REMAIN CALM
OR LIGHT AND VARIABLE FLOW THROUGH AT LEAST 13Z.
TRICKY FORECAST IN TERMS OF PCPN TYPE. DUAL POL MELTING SIGNATURE
IS EVIDENT IN THE LEADING EDGE OF PCPN SOUTH OF CRW AND HTS ABOUT
3K FEET AGL. ATTM...A RELATIVELY WARMER AIR MASS WILL ADVECT FROM
THE SOUTH INTO A MUCH COLDER AIR NORTH ALONG AND NORTH OF A LINE
FROM HTS...CRW...AND BKW. THEREFORE...EXPECT MOST PCPN TO BE
LIQUID REACHING HTS...CRW AROUND 08Z. RAIN MIXED WITH ICE PELLETS
AT BKW AROUND 08Z...TRANSITIONING TO FREEZING RAIN AROUND 10Z
UNDER MVFR CONDITIONS.
EXTENDED PERIOD OF FREEZING RAIN AND ICE AT BKW FROM 10-18Z...AND
EKN FROM 10-20Z. A FEW HOURS ALSO AT CKB ARE EXPECTED STARTING
AROUND 13-19Z. PKB MAY SEE BRIEF ICE AS WELL...BUT MORE LIKELY TO
BE RAIN MIXED WITH ICE PELLETS AROUND 22Z BEFORE TRANSITIONING TO
ALL SNOW BY 04Z THURSDAY.
WIDESPREAD MVFR...AND IFR POSSIBLE AT TIMES LATE OVERNIGHT AND
WEDNESDAY. HOWEVER...LOWLANDS ADJACENT TO THE WESTERN SLOPES SHOULD
EXPERIENCE VFR CEILINGS IN DOWNSLOPING SOUTHEAST FLOW WEDNESDAY.
LOWER VISIBILITIES TO IFR/LIFR AT THE END OF THE PERIOD WITH AREAS
OF SNOW.
FLOW BECOMES STRONG SOUTHEAST LATE OVERNIGHT AND REMAIN SO WEDNESDAY EAST
OF THE OHIO RIVER...AND MODERATE NORTHEAST...ALONG AND WEST OF
THE OHIO RIVER DURING THESE TIMES.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF PRECIPITATION TYPE TRANSITION COULD
VARY. DURATION AND EXTENT OF ICE COULD VARY. DURATION AND EXTENT
OF LOWER CIGS AND VSBYS IN PRECIPITATION COULD ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE WED 12/26/12
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12
CRW CONSISTENCY H H H H M H H M M L M H
HTS CONSISTENCY H H H H H L L L L L L H
BKW CONSISTENCY H L L L L L L L L L L L
EKN CONSISTENCY H H L L L L L L L L L L
PKB CONSISTENCY H H H L L L L L L M M M
CKB CONSISTENCY H H H H L L L L L L L L
AFTER 06Z THURSDAY...
IFR POSSIBLE IN MIXED PRECIPITATION AND RAIN IN SE OHIO AND THE WV
MOUNTAINS WED NIGHT...AND IN SNOW SHOWERS THROUGHOUT THE AREA BUT
MORE SO IN THE MOUNTAINS LATE WEDNESDAY NIGHT INTO THURSDAY. IFR
POSSIBLE IN SNOW SATURDAY INTO SUNDAY...ESPECIALLY IN THE
MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
WVZ011-020-031-032-035>040.
ICE STORM WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ046-047.
OH...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
OHZ067-075-076.
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR OHZ066.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/RPY/SL/26
NEAR TERM...ARJ/TRM/26
SHORT TERM...SL
LONG TERM...RPY
AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1037 PM CST TUE DEC 25 2012
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATE...TEMPS FALLING OFF THE CLIFF THIS EVENING SO LOWERED MINS
TONIGHT BEFORE HIGH LEVEL CLOUDS FILTER NORTHWARD. RADAR SHOWS A
BAND OF LAKE EFFECT SNOW SHOWERS WORKING INTO MANITOWOC COUNTY.
CLOUD TOPS ONLY AROUND 5 K TO MID LAKE WITH THIS BAND SO LIKELY
ONLY FLURRIES OR LIGHT SNOW SHOWERS AT THIS TIME.
TDH
&&
.PREV DISCUSSION...ISSUED AT 524 PM CST TUE DEC 25 2012...
SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW ARCTIC HIGH
PRESSURE CENTERED OVER THE NORTHERN GREAT PLAINS AND NOSING ACROSS
THE WESTERN GREAT LAKES. CLOUDS AND FLURRIES HAVE RETREATED NORTH
OF THE UPPER PENINSULA BORDER EARLY THIS AFTERNOON AND ARE NO LONGER
IMPACTING N-C WISCONSIN. MEANWHILE...LIGHT NE LOW LEVEL FLOW HAS
ALREADY STARTED TO DEVELOP OVER NORTHEAST WISCONSIN AND LAKE CLOUDS
ARE ALREADY PUSHING ACROSS THE FOX VALLEY. SNOW FLURRIES ARE
SHOWING UP ON RADAR JUST OFFSHORE THE KEWAUNEE COAST...AND EVEN WHAT
LOOKS LIKE A MID-LAKE BAND HAS BEEN MOVING EAST OVER CENTRAL LAKE
MICHIGAN. AS DEEPER AND STRONGER NE FLOW DEVELOPS LATER TONIGHT AND
WEDNESDAY...LAKE EFFECT SNOW CHANCES AND AMOUNTS ARE THE MAIN
FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE RIDGE AXIS WILL BE EXTENDING ACROSS
NORTHERN WISCONSIN AND LAKE MICHIGAN AT THE START OF THE
EVENING...BUT WILL SHIFT NORTHWARD THROUGH THE NIGHT. AS STRONG LOW
PRESSURE MOVES OVER THE SOUTHERN OHIO VALLEY...WIND DIRECTION WILL
BECOME NORTHEASTERLY FROM THE SURFACE UP TO 700MB. 12Z GRB SOUNDING WAS
PRETTY DRY ABOVE 900MB THIS MORNING...BUT ONCE THE NE FLOW BECOMES
ESTABLISHED...OUR AIR WILL BE COMING FROM NORTHERN LAKE MICHIGAN
WHERE THE 12Z APX SOUNDING WAS CONSIDERABLY MORE SATURATED...UP TO
825MB. SINCE AMPLE CLOUD COVER ALREADY EXISTS OVER NORTHERN LAKE
MICHIGAN...AND SHOWING NO SIGNS OF DISSIPATING...SEE NO REASON WHY
THE LAKE CLOUDS COULD NOT CONTINUE TO PUSH ACROSS THE WESTERN FOX
VALLEY AND POSSIBLY EXPAND INTO CENTRAL WISCONSIN. LAKE EFFECT SNOW
POTENTIAL WILL IMPROVE THROUGH THE NIGHT WHEN 1000-850MB FLOW
STRENGTHENS TO 15 KTS. COMBINED WITH LENGTHENING FETCHES AND DELTA
T/S AROUND 16C...LAKE EFFECT SNOW SHOWERS LOOK LIKELY LATE TONIGHT
OVER E-C AND NE WISCONSIN. THINK IT WILL TAKE AWHILE FOR THE
MULTIPLE BANDS TO DEVELOP WITH WINDS LIGHT THIS EVENING. SO WILL
SHOW ACCUMS UP TO AN INCH OVER E-C WISCONSIN...MAINLY AFTER
MIDNIGHT. ELSEWHERE...CIRRUS WILL INCREASE FROM THE SW AFTER
MIDNIGHT AHEAD OF A NORTHERN STREAM SHORTWAVE. LOWS SLIGHTLY BELOW
ZERO OVER N-C WISCONSIN...TO THE UPPER TEENS NEAR LAKE MICHIGAN.
WEDNESDAY...NORTHEAST FLOW WILL CONTINUE UNABATED FOR THE ENTIRE
DAY. WITH A CIRRUS SHIELD OVERHEAD...DELTA T/S WILL REMAIN AROUND
15C WITH GREAT FETCH LENGTHS AND 1000-850MB WINDS BETWEEN 15-20KTS.
IN ADDITION...AN INCOMING SHORTWAVE TROUGH WILL LIFT INVERSION
HEIGHTS TO NEAR 800MB (PROBABLY UNDERESTIMATED DUE TO LAKE MICHIGAN
MODIFICATIONS) AND CREATE LARGE-SCALE ASCENT...WHICH WILL SUBTLY IMPROVE
LES POTENTIAL. WENT A LITTLE MORE BULLISH WILL SNOWFALL POTENTIAL
DUE TO THESE FACTORS...AND WILL SHOW 1-2 INCHES IN THE FORECAST. AM
CONCERNED THAT THE LONG FETCH LENGTHS AND A PERSISTENT WIND
DIRECTION WILL LEAD TO HIGHER AMOUNTS SINCE THIS COULD LEAD TO
ORGANIZED BANDING. ELSEWHERE...PLENTY OF CIRRUS OVERHEAD WILL CREATE
TO PARTLY SUNNY TO MOSTLY CLOUDY CONDITIONS. HIGHS MAINLY IN THE LOW
TO MID 20S.
LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
LAKE EFFECT SNOW SHOWERS WILL BE DIMINISHING EARLY IN THE PERIOD
AS LOW-LEVEL WINDS BACK AND SURFACE HIGH PRESSURE MOVES IN.
PACIFIC ENERGY MOVES ON SHORE WED AND QUICKLY MOVES INTO MIDWEST
BY LATE IN WEEK. ASSOCIATED SHORTWAVE TROF AND SURFACE WAVE MOVE
ACROSS REGION ON FRIDAY. ENOUGH MOISTURE ASSOCIATED WITH SYSTEM
TO PRODUCE LIGHT COATING OF SNOW ACROSS AT LEAST THE SOUTHERN
THIRD OR SO OF FORECAST AREA.
SEASONAL TEMPS DURING PERIOD AS ARCTIC AIR...FOR THE MOST PART...
REMAINS BOTTLE UP IN CANADA...NORTH AND NORTHEAST OF WI.
&&
.AVIATION...VFR CONDITIONS EXPECTED TONIGHT INTO WEDNESDAY OVER
NORTH CENTRAL AND MUCH OF CENTRAL WISCONSIN. PATCHY MVFR CIGS DUE
TO A FLOW OFF LAKE MICHIGAN WILL BECOMING MORE WIDESPREAD BY
WEDNESDAY AS COLD AIR ON NORTHEAST WINDS INCREASE. PATCHY MVFR
CIGS FROM LAKE SUPERIOR ORIGIN MAY ALSO WORK INTO PARTS OF NORTH
CENTRAL WISCONSIN LATER TONIGHT INTO WEDNESDAY. SCATTERED MVFR
VSBYS DUE TO SNOW SHOWERS LIKELY OVER EAST CENTRAL WISCONSIN AND
ESPECIALLY ALONG THE LAKE MICHIGAN SHORELINE.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
548 AM CST WED DEC 26 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
THE FORECAST AREA WILL REMAIN IN THE WEAK CAA
TODAY AS THE STRONG WINTER STORM TO THE SOUTHEAST CONTINUES TO PRESS
FURTHER EAST...WHILE THE SURFACE HIGH CENTERED OVER THE
DAKOTAS/NORTHERN MINNESOTA WILL SLOWLY NUDGE INTO NORTHERN IOWA.
WILL SEE HIGH CIRRUS SHIELD CURRENTLY OVER MUCH OF THE FORECAST AREA
DRIFT EAST WITH THE STRONG SURFACE LOW. THIS CLOUD DECK WILL HINDER
MAX TEMPS SLIGHTLY TODAY...ESPECIALLY ACROSS THE EAST. SO WENT
CLOSER TO THE COOLER MAV MOS ACROSS THE EAST...AND MORE TOWARDS THE
WARMER SREF/NAM BLEND TO THE WEST.
.LONG TERM /TONIGHT THROUGH TUESDAY/...
STRONG UPPER LEVEL PV ANOMALY AND ASSOCIATED SHORT WAVE CURRENTLY
MOVING INTO CNTRL CALIFORNIA THIS MORNING...IS THE PRIMARY SYSTEM
EXPECTED TO IMPACT IOWA THROUGH THE PERIOD. ANOTHER STRONG SYSTEM IS
MOVING THROUGH THE SOUTHEASTERN CONUS WILL LIFT THROUGH THE UPPER
OHIO VALLEY AND INTO THE NEW ENGLAND REGION TODAY THROUGH THURSDAY.
THIS SYSTEM IS DELAYING THE ARRIVAL OF THE WESTERN ENERGY A BIT AND
MORE INTO THURSDAY NIGHT AND FRIDAY. BEFORE THEN...RIDGE OF HIGH
PRESSURE WILL SLIDE EAST THROUGH CNTRL IA TONIGHT. OVERNIGHT LOW
TEMPERATURES TONIGHT ARE DIFFICULT WITH A FAIR AMOUNT OF CLOUD
DEBRIS UNDER THE HIGH. TEMPERATURES UNDER THE RIDGE CURRENTLY ARE
ZERO TO 5 ABOVE AND READINGS SHOULD BE SIMILAR TONIGHT THOUGH CLOUD
COVER SHOULD BEGIN INCREASING LATE AHEAD OF THE NEXT SYSTEM.
GOOD THETA-E ADVECTION COMMENCES OVER SOUTHWEST IA THURSDAY MORNING
AND LIFTING INTO CNTRL IA BY THE AFTERNOON. THE ARRIVAL WILL
COINCIDE WITH THE ARRIVAL OF QG FORCING ASSOCIATED WITH THE
APPROACHING SHORT WAVE. THE INITIAL FORCING WILL BE BURNT SATURATING
THE DRY AIR BELOW 750 MB. ONCE SATURATION OCCURS...EXPECT A
PROLONGED PERIOD OF GENERALLY LIGHT SNOW THAT COULD BECOME MODERATE
AT TIMES CENTRAL AND NORTH. ONCE AGAIN A STRONGER SYSTEM WILL
DEVELOP TO THE SOUTH DURING THIS PERIOD. THE SOUTHERN SYSTEM WILL
STREAM ADDITIONAL MOISTURE NORTHWARD ALONG THE INVERTED TROUGH AXIS.
FORCING PIVOTING THROUGH THE STATE INTO FRIDAY ALONG WITH SOME
MOISTURE FLOW FROM THE WARM CONVEYOR OF THE SYSTEM TO THE SOUTH WILL
KEEP SNOW CONTINUING INTO FRIDAY. STILL EXPECT SNOWFALL AMOUNTS OF 1
TO 3 INCHES TO BE COMMON WITH SNOW TO LIQUID RATIOS OF 15-20 TO 1
LIKELY. A DEEP DENDRITIC GROWTH ZONE DESPITE RELATIVE WEAK OVERALL
FORCING COULD PUSH A FEW AREAS ABOVE 3 INCHES...ESPECIALLY OVER THE
NORTH. FORTUNATELY...THERE WILL BE LITTLE TO NO WIND TO BLOW THIS
FLUFFY NEW SNOW AROUND.
THE REMAINDER OF THE FORECAST WILL BE QUIET THROUGH THE WEEKEND INTO
EARLY NEXT WEEK. THE END OF THE WEEK SYSTEM WILL SHIFT EAST WITH
WEAK RIDGING INTO IOWA FOR THE WEEKEND. A GOOD REMAINING SNOW PACK
WILL LIMIT HIGH TEMPERATURES THROUGH THE PERIOD BUT MOSTLY DRY
CONDITIONS WILL PREVAIL. THE STATE WILL BE STUCK BETWEEN AN EASTERN
CANADA/NORTHEAST CONUS TROUGH AND AN UPPER LEVEL LOW DROPPING INTO
THE DESERT SOUTHWEST BY EARLY NEXT WEEK.
&&
.AVIATION...26/12Z
MVFR STRATUS WILL PERSIST ACROSS SOUTHEAST IOWA THROUGH THE MORNING
HOURS. RAP40/NAM12 HAVE THE STRATUS DECK SHIFTING FURTHER WEST BUT
SOMEWHAT DISSIPATING PAST 15Z. MAY SEE A BRIEF PERIOD OF MVFR CIGS
AT DSM/ALO...BUT LOW CONFIDENCE WITH STRATUS MOVING THAT FAR WEST.
THE LATEST HRRR KEEPS THE STRATUS IN ITS CURRENT LOCATION BEFORE
MOVING IT EASTWARD LATER THIS MORNING. LARGE SURFACE HIGH BUILDS
INTO THE STATE TONIGHT WITH A FAIRLY STRONG INVERSION DEVELOPING
OVERNIGHT. THIS LEADS TO A POTENTIAL FOR SOME LOW LEVEL MOISTURE
TRAPPED RESULTING IN FOG/STRATUS. LEFT VFR FOR NOW DUE TO LOW
CONFIDENCE WITH AMOUNT OF LOW LEVEL MOISTURE PRESENT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
702 AM EST WED DEC 26 2012
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL TRACK FROM THE TENNESSEE
VALLEY ACROSS THE MID ATLANTIC TODAY...WITH THE ASSOCIATED COLD
FRONT PUSHING OFF THE COAST BY EARLY THURSDAY MORNING. HIGH
PRESSURE RETURNS THURSDAY AFTERNOON THROUGH FRIDAY. ANOTHER LOW
PRESSURE SYSTEM WILL AFFECT THE REGION ON SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WX ANALYSIS DEPICTS A ~995 MB SFC LOW CENTERED ACRS ERN
TENNESSEE...AND A ~1032 MB SFC HIGH PRESSURE NORTH OF THE CENTRAL
GREAT LAKES. TEMPS ARE STILL ABOVE FREEZING OVER ALL OF THE
CWA...EVEN IN THE PIEDMONT...BUT OBS HAVE REPORTED LIGHT SNOW
AND/OR SLEET AT LKU/CHO AND NHK. INITIAL BATCH OF STEADIER
MODERATE PRECIP IS NOW LIFTING OFF TO THE NE OF RICHMOND...WITH
LIGHTER MORE SPOTTY PRECIP ALLOWING FOR RAIN TO MIX BACK IN AT
LKU/CHO. HAVE ADJUSTED FCST FOR CURRENT CONDITIONS...BUT LITTLE
CHANGE IN OVERALL THINKING FOR TODAY...AS PRECIP RATES INCREASE
THERE IS STILL THE POTENTIAL FOR MIXED SNOW/SLEET OVER FAR NORTHERN
TIER OF CWA THROUGH 15Z...BECOMING CONFINED TO WRN LOUISA/FLUVANNA
15Z-17Z AND THEN SHOULD BE ALL RAIN THEREAFTER. LITTLE TO NO
ACCUMULATION (IF THERE IS ANY ACCUMULATION IT SHOULD BE LIGHT AND
LIMITED TO GRASSY SURFACES OVER WRN LOUISA/FLUVANNA...NOT CLOSE TO ENOUGH
FOR AN ADSY).
THE OTHER CONCERN TODAY IS POTENTIAL FOR SEVERE WX. SPC HAS MUCH
OF THE CWA OUTLINED IN SLIGHT RISK FOR SEVERE THIS AFTN/EARLY
EVENING. BASED ON WHAT OCCURRED YESTERDAY IN THE DEEP SOUTH (LIGHTNING
STRIKES OCCURRING WHERE LI`S HAVE BEEN +5 OR GREATER...BUT WITH
NEGATIVE SHOWALTER INDICES (ELEVATED INSTABILITY)...HAVE EXTENDED
CHC FOR TSTMS LATER THIS AFTN/EARLY EVENING A BIT FARTHER NORTH TO
INCLUDE MUCH OF CENTRAL VA/METRO RICHMOND. STRONG 0-6 KM BULK
SHEAR (60-80 KT) WILL BE CROSSING THE AREA AFTER 18Z...AND THIS
SHOULD BE ENOUGH TO GENERATE AT LEAST SOME EMBEDDED TSTMS EVEN
WITH NO SFC BASED CAPES. HAVE FOCUSED CHC TSTMS FROM 2 PM-6 PM
WELL NORTH OF WHERE THE LOW LEVEL INSTABILITY IS FORECAST TO
OCCUR..FOLLOWING CLOSE TO RAP NEGATIVE SHOWALTER INDICES. WITH
THAT SAID...THINK THE CHC FOR SEVERE TSTMS WILL BE MUCH FARTHER
SOUTH...CONFINED TO AREAS WHERE DEW PTS GET INTO THE MID 50S OR
HIGHER AND TEMPS REACH 60 F OR HIGHER. LOOKING AT SPC STORM
REPORTS...THIS IS WHAT HAS HAPPENED THUS FAR. THIS TRANSLATES TO
BEST POTENTIAL FOR SEVERE WX OVER FAR SE/SRN VA AND NE NC. HAVE
MENTIONED THIS IN THE HWO AND HAVE ENHANCED WORDING IN THE GRIDDED
FCST FOR FAR SE VA/NE NC.
OVERALL...RAINFALL RATES ACROSS THE AREA WILL BECOME MODERATE TO
OCCASIONALLY HEAVY AHEAD OF/WITH THE COLD FRONTAL PASSAGE THIS AFTN/EVENING.
PRECIP TOTALS THROUGH TONIGHT/THU RANGE FROM 1.25 TO 1.75 INCHES
(WHERE HIGHER AMTS WILL BE LOCATED ALONG THE IMMEDIATE COAST).
SOME AREAS COULD SEE LOCALLY HIGHER AMTS.
HIGHS AROUND 40 EXTREME NW TO THE LWR-MID 60S FAR SE VA AND POSSIBLY
INTO THE UPPER 60S IN NE NC.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
STRONG SFC LOW WILL LIFT NE OF THE AREA LATE TONIGHT INTO EARLY THU
MORNING...WITH THE TRAILING UPPER LOW MOVING ACROSS NRN VA/SE MD
AND DE. WILL LINGER POPS ACROSS MOST NE AREAS (INCLUDING PORTIONS
OF THE TIDEWATER AREA) INTO EARLY THU MORNING. LOWS WED NIGHT
RANGING FM THE MID 30S TO MID 40S. CHILLY W/NW WINDS AND DRIER AIR
EXPECTED ON THU...AS THE STRONG LO MOVES NE OFF THE NEW ENGLAND
CST. PARTLY TO MOSTLY SUNNY (EXCEPT MOSTLY CLOUDY ERN SHORE) WITH
HIGHS IN THE MID 40S NE TO LOWER 50S S/SW. FRI WILL BE MOSTLY CLEAR
WITH COLDER LOW TEMPS IN THE MID 20S TO MID 30S AND HIGHS INTO
THE UPPER 40S TO AROUND 50.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AMPLIFIED FLOW PATTERN CONTINUES DURING THE FIRST PART OF THE
EXTENDED PERIOD 12Z GFS AND ECMWF REMAIN SOMEWHAT APART WITH
REGARD TO SFC LOW AND ASSOCIATED FRONT MOVING THROUGH THE AREA IN
THE SAT/SUN TIME FRAME. LAST 2 RUNS OF THE GFS HAVE BEEN FURTHER
NORTH...SUGGESTING ONLY A BRIEF PERIOD OF WINTRY PRECIP ACROSS OUR
NWRN COUNTIES SAT MORNING. ECMWF IS A BIT FURTHER NORTH THAN
PREVIOUS RUN...BUT IS WARMER...AND DELAYS DEEPENING OF SFC CYCLONE
UNTIL IT PASSES EAST OF AREA. UPSTART OF THIS IS HAVE MAINTAINED
MUCH OF THE PREVIOUS EXTENDED FORECAST WITH REGARD TO PRECIP...
ALTHOUGH AM A BIT FASTER IN PRECIP EXITING...PER LATEST GUIDANCE.
STILL EXPECT A POTENTIAL MIX OF RAIN/SNOW ACROSS THE NWRN COUNTIES...
BUT HAVE KEPT ALL RAIN ALL AREAS FROM 18Z SAT ON. PRECIP ENDS ON
ALL MODELS BEFORE 06Z SUNDAY...AND HAVE KEPT SUNDAY/MONDAY DRY
ATTM. AS FOR TEMPS SAT...COULD BE A SIGNIFICANT GRADIENT FROM NW
TO SE...ESPECIALLY IF GFS IS CORRECT. IN SITU WEDGE ON BOTH MODELS
IMPLIES NWRN AREAS POSSIBLY NOT GETTING ABOVE 40 DEG. SE VA/NE NC
SHOULD REACH 50 OR HIGHER...WITH UPR 50S A GOOD BET SHOULD GFS
VERIFY.
TEMPS SUNDAY/MONDAY CLOSE TO NORMAL...WITH MAX TEMPS 40S TO LOW 50S
AND MIN TEMPS 20S TO LOW 30S. NEXT BOUNDARY CROSSES REGION IN THE
MONDAY NIGHT/TUESDAY TIME FRAME. RIGHT NOW...NOT A LOT OF PRECIP
EXPECTED WITH FRONT...ALTHO SCTD SHOWERS POSSIBLE.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
STRONG SFC LOW PRESSURE WILL CONTINUE TO LIFT OUT OF THE DEEP
SOUTH EARLY THIS MORNING AS HIGH PRESSURE REMAINS WEDGED OVER THE MID
ATLANTIC. CURRENTLY...BKN/OVC SKIES WITH DECKS GENERALLY 3 TO 6K
FT AGL WILL CONTINUE TO LOWER THROUGH 12Z UNDER NELY FLOW ALOFT.
THE EXCEPTION WILL BE IN SE VA/NE NC WHERE NELY FLOW WILL RESULT
IN LOCALIZED IFR CIGS THROUGH EARLY MORNING. OVERRUNNING WILL
SPREAD LIGHT/MODERATE RAIN NEWD THIS MORNING ACROSS THE REGION. IN
ADDITION...AN INCREASING LOW LEVEL JET MAY ENHANCE SOME WIND SHEER
THIS MORNING AT KRIC AND KSBY. WILL LEAVE OUT OF TAFS AS TIMING
WILL BE DIFFICULT AND CONFIDENCE IS LOW...SO WILL MONITOR AND
AMEND IF NEEDED. WINDS THROUGH 12Z WILL BE NELY AT 5 TO 15 KT WITH
GUSTS NEAR THE COAST UP TO 20 KT. EXPECT TO SEE THE CLOUDS
GRADUALLY LOWER WITH THE LOW LEVELS BECOMING SATURATED BETWEEN 12Z
AND 15Z. THIS WILL YIELD WIDESPREAD MVFR CONDITIONS DEVELOPING
AND AS THE ISENTROPIC LIFT INCREASES. CIGS AND VSBYS DROP TO IFR
LEVELS WITH THE INCREASING RAIN THREAT. THE CHALLENGE COMES DOWN
TO THE STRENGTH OF THE WEDGE...WHICH THE MODELS TRY TO ERODE
QUICKLY WITH THE SFC LOW FORMING OVER THE PIEDMONT AND LIFTING NE.
BUT EXPECT THAT THE WEDGE WILL BE STRONG WITH THE LOW FORMING JUST
EAST OF I-95. THIS WILL ALLOW THE WINDS TO SWITCH TO SE OR E FOR
ORF/ECG/SBY AND MAYBE AT PHF...BUT ANTICIPATE THAT RIC WILL REMAIN
CLOSER TO THE WEDGE SO DO NOT SHOW A GREAT DEAL OF IMPROVEMENT
LATE IN THE PERIOD...KEEPING THE IFR CONDITIONS THROUGH THE TAF.
THE OTHER SITES SHOULD BREAK INTO THE WARM SECTOR WHICH SHOULD
BRING THE CEILINGS AND VSBY BACK TO MVFR OR EVEN VFR CONDITIONS
AHEAD OF THE COLD FRONT...WHICH SHOULD CROSS BETWEEN 00Z AND 3Z.
WINDS WILL BE STRONGEST NEAR THE COAST WITH GUSTS UP TO 25-30 KT
THIS AFTERNOON.
THERE COULD STILL BE A CHANCE FOR A TSTM AS THE COLD FRONT PUSHES
THROUGH ON WEDNESDAY EVENING WITH BEST CHC AT ORF AND ECG.
CONDITIONS WILL IMPROVE BACK TO VFR BY THURSDAY AND CONTINUE VFR
ON FRIDAY. NEXT LOW APPROACHES FOR THE WEEKEND AND THIS COULD
AGAIN GENERATE MORE MVFR AND IFR CEILINGS.
&&
.MARINE...
EXTENDED GALE WARNING FOR NORTHERN COASTAL ZONES THROUGH THURSDAY
AFTERNOON WITH EARLY MORNING UPDATE. PER PREV DISCUSSION
BELOW...THERE MAY BE A LULL IN GALE FORCE WINDS WEDS NIGHT/THURS
MORNING...BUT ANY LULL WILL BE SHORT LIVED. STRONG CAA WILL INCREASE
EARLY THURSDAY MORNING AS WINDS BECOME MORE W/NW ALLOWING FOR STRONG
MIXING OVER THE WATER AGAIN THROUGH THURSDAY AFTERNOON.
.PREV DISCUSSION...
STRONG SFC LOW PRESSURE SYSTEM LOCATED OVER THE TN VALLEY WILL
CONTINUE TO LIFT TO THE NE THIS MORNING AND CROSS THE REGION THIS
AFTERNOON. THE LOW WILL THEN INTENSIFY NE OF THE REGION. THIS WILL
BRING AN EXTENDED PERIOD OF STRONG WINDS/GALES AND HIGH SEAS/WAVES
TO THE MARINE AREA. NE WINDS HAVE INCREASED OVER THE WATERS EARLY THIS
MORNING WITH WINDS OVER THE BAY ALREADY REACHING SCA CONDITIONS.
WAVES BUILDING TO 3 TO 4 FT IN THE BAY WITH SEAS BUILDING TO
NEAR 5 FT IN THE SOUTHERN COASTAL WATERS. THUS HAVE OPTED TO BEGIN
SCA HEADLINES WITH THIS UPDATE. WILL ALSO BEGIN SCA HEADLINES FOR
THE ERN VA RIVERS AND THE CURRITUCK SOUND AS SCA CONDITIONS ARE
OBSERVED. WILL MAINTAIN GALE WARNING TIMING FOR THE NORTHERN COASTAL
ZONES AS WINDS/SEAS WILL BE QUICK TO RISE LATER THIS MORNING. SEAS
EXPECTED TO BUILD TO 10 FT 20 NM OUT BY MID AFTERNOON. AS THE LOW
LIFTS OVER THE WATERS THIS EVENING INTO THE OVERNIGHT...STILL
ANTICIPATE LOW LEVEL INVERSION OVER THE WATER TO SUPPRESS 30-40 KT
WINDS A FEW HUNDRED FEET AGL. GRADIENT INCREASES BEHIND FRONT AS SFC
LOW INTENSIFIES AND CAA INCREASES. HAVE OPTED TO EXTEND ALL SCA
HEADLINES AN ADDITIONAL 12 HOURS THROUGH THURS AFTERNOON.
BASED ON THE AFOREMENTIONED INVERSION...THERE COULD BE A LULL IN
GALES THURSDAY MORNING (ALTHOUGH STRONG SCA CONDITIONS STILL
EXPECTED) BEFORE CAA KICKS IN RESULTING IN BETTER MIXING. WINDS WILL
BECOME MORE W/NW THURSDAY AFTERNOON WITH GALES LIKELY FOR THE NRN
COASTAL WATERS AGAIN THURSDAY.
A SIMILAR EVENT EXPECTED SATURDAY NIGHT INTO EARLY MONDAY AS NEXT
FRONT AND DEEPENING SFC LOW CROSS REGION.
&&
.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES CONTINUE TO RUN 1.5 TO 2 FT ABOVE NORMAL AT OCEAN
CITY...BISHOPS HEAD AND CAMBRIDGE THIS AFTERNOON TO THURS MORNING
TIMEFRAME. THIS AFTERNOON/EVENINGS CYCLE IS THE LOWER OF THE 2
HIGH TIDES...SO TIDES WILL FALL BELOW ADVISORY CRITERIA TODAY.
TIDES ALSO EXPECTED TO FALL BELOW ADVISORY CRITERIA AGAIN TONIGHT.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ630>638-
656-658.
GALE WARNING FROM 10 AM THIS MORNING TO 9 PM EST THIS EVENING
FOR ANZ650-652-654.
&&
$$
SYNOPSIS...MAM
NEAR TERM...LKB
SHORT TERM...BMD/LKB
LONG TERM...JAB
AVIATION...SAM
MARINE...SAM
TIDES/COASTAL FLOODING...AKQ
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
810 AM CST WED DEC 26 2012
.UPDATE...
ISSUED AT 809 AM CST WED DEC 26 2012
HAVE CANCELLED REMAINING ADVISORIES AND WARNINGS. BACK EDGE OF THE
ACCUMULATING SNOW IS CURRENTLY EXITING THE AREA.
ISSUED AT 553 AM CST WED DEC 26 2012
UPDATING FORECAST TO EXPIRE WARNINGS/ADVISORIES IN MISSOURI AND
CANCEL ST. CLAIR AND MONROE COUNTIES FROM THE WINTER WEATHER
ADVISORY IN ILLINOIS. SHARP BACK EDGE TO THE SNOW IS PROGRESSING
EASTWARD ANY ADDITIONAL ACCUMULATIONS IN METRO EAST WILL BE LITTLE
IF ANY.
BRITT
&&
.SHORT TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TODAY)
MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH
WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY
CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL
AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER
FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND
SPEEDS CONTINUE TO INCREASE.
LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS
1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR
SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED
IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY.
IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS
COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN
FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS
QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE
THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH
CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO
ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS
THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS
TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND
650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE
WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS
WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST
MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA
AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS
WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES
TO THE EAST.
BRITT
&&
.LONG TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TONIGHT THROUGH TUESDAY)
TONIGHT AND THURSDAY...CONFIDENCE HIGH
RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND
SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER
OVER AREAS OF FRESH SNOW COVER.
THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW
NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS
ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS.
GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD
TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW
ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD
SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN
THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION.
WEEKEND...CONFIDENCE MEDIUM
SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE
REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE.
NEXT WEEK...CONFIDENCE LOW
MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY
NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH
ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN
CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF
CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO
THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE
CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT
CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT
TEMPERATURES NEAR NORMAL VALUES.
CVKING
&&
.AVIATION...
ISSUED AT 514 AM CST WED DEC 26 2012
BACK EDGE OF A BAND OF SNOWFALL EXTENDS FROM NEAR KBLV TO KFAM AND
WILL CONTINUE TO MOVE EAST THIS MORNING. HAVE REMOVED ALL SNOW AND
IFR CONDITIONS FROM THE TAFS. KUIN IS CURRENTLY VFR...WITH MVFR
CIGS AT KCOU AND THE ST. LOUIS METRO TAF SITES. DO EXPECT CIGS TO
IMPROVE TO VFR AT THESE SITES LATER THIS MORNING. N-NWLY WINDS
SUSTAINED AROUND 15KTS WILL CAUSE SOME CROSSWIND PROBLEMS ON EAST-
WEST ORIENTED RUNWAYS UNTIL MID-AFTERNOON.
SPECIFICS FOR KSTL...EXPECT NO MORE THAN FLURRIES AS THE STORM
SYSTEM BEGINS TO MOVE AWAY FROM THE AREA. EXPECT CIGS TO CLIMB
BACK ABOVE 2000FT IN THE NEXT FEW HOURS BASED ON OBSERVATIONS FROM
UPWIND AIRPORTS. EXPECT CURRENT NORTHERLY WINDS TO SLIGHTLY BACK
TO THE NORTHWEST THIS MORNING.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
556 AM CST WED DEC 26 2012
.UPDATE...
ISSUED AT 553 AM CST WED DEC 26 2012
UPDATING FORECAST TO EXPIRE WARNINGS/ADVISORIES IN MISSOURI AND
CANCEL ST. CLAIR AND MONROE COUNTIES FROM THE WINTER WEATHER
ADVISORY IN ILLINOIS. SHARP BACK EDGE TO THE SNOW IS PROGRESSING
EASTWARD ANY ADDITIONAL ACCUMULATIONS IN METRO EAST WILL BE LITTLE
IF ANY.
BRITT
&&
.SHORT TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TODAY)
MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH
WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY
CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL
AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER
FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND
SPEEDS CONTINUE TO INCREASE.
LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS
1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR
SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED
IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY.
IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS
COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN
FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS
QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE
THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH
CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO
ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS
THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS
TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND
650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE
WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS
WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST
MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA
AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS
WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES
TO THE EAST.
BRITT
&&
.LONG TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TONIGHT THROUGH TUESDAY)
TONIGHT AND THURSDAY...CONFIDENCE HIGH
RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND
SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER
OVER AREAS OF FRESH SNOW COVER.
THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW
NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS
ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS.
GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD
TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW
ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD
SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN
THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION.
WEEKEND...CONFIDENCE MEDIUM
SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE
REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE.
NEXT WEEK...CONFIDENCE LOW
MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY
NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH
ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN
CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF
CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO
THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE
CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT
CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT
TEMPERATURES NEAR NORMAL VALUES.
CVKING
&&
.AVIATION...
ISSUED AT 514 AM CST WED DEC 26 2012
BACK EDGE OF A BAND OF SNOWFALL EXTENDS FROM NEAR KBLV TO KFAM AND
WILL CONTINUE TO MOVE EAST THIS MORNING. HAVE REMOVED ALL SNOW AND
IFR CONDITIONS FROM THE TAFS. KUIN IS CURRENTLY VFR...WITH MVFR
CIGS AT KCOU AND THE ST. LOUIS METRO TAF SITES. DO EXPECT CIGS TO
IMPROVE TO VFR AT THESE SITES LATER THIS MORNING. N-NWLY WINDS
SUSTAINED AROUND 15KTS WILL CAUSE SOME CROSSWIND PROBLEMS ON EAST-
WEST ORIENTED RUNWAYS UNTIL MID-AFTERNOON.
SPECIFICS FOR KSTL...EXPECT NO MORE THAN FLURRIES AS THE STORM
SYSTEM BEGINS TO MOVE AWAY FROM THE AREA. EXPECT CIGS TO CLIMB
BACK ABOVE 2000FT IN THE NEXT FEW HOURS BASED ON OBSERVATIONS FROM
UPWIND AIRPORTS. EXPECT CURRENT NORTHERLY WINDS TO SLIGHTLY BACK
TO THE NORTHWEST THIS MORNING.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 6 AM CST EARLY THIS MORNING FOR
MADISON MO-ST. FRANCOIS MO-STE. GENEVIEVE MO.
WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
IRON MO-REYNOLDS MO-WASHINGTON MO.
IL...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR BOND IL-CLINTON
IL-FAYETTE IL.
WINTER STORM WARNING UNTIL NOON CST TODAY FOR MARION IL-RANDOLPH
IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
514 AM CST WED DEC 26 2012
.SHORT TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TODAY)
MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH
WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY
CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL
AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER
FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND
SPEEDS CONTINUE TO INCREASE.
LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS
1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR
SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED
IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY.
IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS
COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN
FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS
QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE
THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH
CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO
ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS
THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS
TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND
650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE
WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS
WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST
MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA
AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS
WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES
TO THE EAST.
BRITT
&&
.LONG TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TONIGHT THROUGH TUESDAY)
TONIGHT AND THURSDAY...CONFIDENCE HIGH
RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND
SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER
OVER AREAS OF FRESH SNOW COVER.
THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW
NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS
ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS.
GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD
TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW
ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD
SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN
THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION.
WEEKEND...CONFIDENCE MEDIUM
SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE
REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE.
NEXT WEEK...CONFIDENCE LOW
MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY
NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH
ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN
CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF
CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO
THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE
CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT
CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT
TEMPERATURES NEAR NORMAL VALUES.
CVKING
&&
.AVIATION...
ISSUED AT 514 AM CST WED DEC 26 2012
BACK EDGE OF A BAND OF SNOWFALL EXTENDS FROM NEAR KBLV TO KFAM AND
WILL CONTINUE TO MOVE EAST THIS MORNING. HAVE REMOVED ALL SNOW AND
IFR CONDITIONS FROM THE TAFS. KUIN IS CURRENTLY VFR...WITH MVFR
CIGS AT KCOU AND THE ST. LOUIS METRO TAF SITES. DO EXPECT CIGS TO
IMPROVE TO VFR AT THESE SITES LATER THIS MORNING. N-NWLY WINDS
SUSTAINED AROUND 15KTS WILL CAUSE SOME CROSSWIND PROBLEMS ON EAST-
WEST ORIENTED RUNWAYS UNTIL MID-AFTERNOON.
SPECIFICS FOR KSTL...EXPECT NO MORE THAN FLURRIES AS THE STORM
SYSTEM BEGINS TO MOVE AWAY FROM THE AREA. EXPECT CIGS TO CLIMB
BACK ABOVE 2000FT IN THE NEXT FEW HOURS BASED ON OBSERVATIONS FROM
UPWIND AIRPORTS. EXPECT CURRENT NORTHERLY WINDS TO SLIGHTLY BACK
TO THE NORTHWEST THIS MORNING.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER STORM WARNING UNTIL 6 AM CST EARLY THIS MORNING FOR
MADISON MO-ST. FRANCOIS MO-STE. GENEVIEVE MO.
WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
IRON MO-REYNOLDS MO-WASHINGTON MO.
IL...WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR BOND IL-CLINTON
IL-FAYETTE IL-MONROE IL-ST. CLAIR IL.
WINTER STORM WARNING UNTIL NOON CST TODAY FOR MARION IL-RANDOLPH
IL-WASHINGTON IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
638 AM MST WED DEC 26 2012
.SHORT TERM...VALID FOR TDY AND THU...
UPDATED FORECAST TO EXTEND MORNING POPS FURTHER EAST AND INCREASE
TO LIKELY OVER HIGHER ELEVATIONS WEST THIS MORNING. SHORTWAVE AND
SOME MID LEVEL WARM ADVECTION MOVING ACROSS WESTERN AND CENTRAL
MONTANA THIS MORNING ARE PRODUCING MORE PRECIPITATION THAN
EXPECTED. SNOW HAS DEVELOPED AS FAR NORTH AND EAST AS GREAT FALLS
THIS MORNING...AN AREA MODELS HAVE NOT BEEN ADVERTISING ANY
PRECIPITATION. 06Z NAM AND LATES RAP HAVE SHOWN INCREASED LIFT AND
MOISTURE ADVECTION FROM BIG HORN AND TREASURE COUNTY WEST. ALSO
NOTING MORE COOLING CLOUD TOPS OVER NORTHERN WYOMING SHIFTING INTO
SOUTH CENTRAL MONTANA THAN WAS EXPECTING HINTING THAT UPSTREAM
SYSTEM MAY BE MOVING FASTER AND MAY BE STRONGER THAN 00Z MODELS
WERE FORECASTING. AS A RESULT INCREASED AND SPREAD POPS FURTHER
EAST THIS MORNING...AND INCREASED AFTERNOON POPS 10 TO 20 PERCENT
OVER CENTRAL AND EASTERN ZONES ANTICIPATING A FASTER ARRIVAL OF
SYSTEM INTO WYOMING THAT IS CURRENTLY IN UTAH. ANY SNOW THIS
MORNING INTO EARLY AFTERNOON WILL BE VERY LIGHT. CHAMBERS
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
CONFIDENCE IN THE EXTENDED FORECAST REMAINS AVERAGE THROUGH THE
WEEKEND...WITH CONFIDENCE DECREASING FOR EARLY NEXT WEEK.
FRIDAY WILL BRING UPPER-LEVEL NORTHWESTERLY FLOW ACROSS THE
FORECAST AREA IN THE WAKE OF A PACIFIC TROUGH. THIS PATTERN WILL
ALLOW A SURFACE HIGH PRESSURE TO BUILD SOUTH AND WEST OF THE AREA
WITH SURFACE PRESSURE FALLS ALONG THE FRONT RANGE. THIS WILL ALLOW
FOR WESTERLY DOWNSLOPE FLOW TO INCREASE DURING THE DAY ON FRIDAY. THE
MAGNITUDE OF WARMING DUE TO THE DOWNSLOPE FLOW WILL BE INHIBITED
ON FRIDAY DUE TO LINGERING SNOW COVER ACROSS THE AREA AND A COLD
AIR MASS IN PLACE WEST OF THE ROCKIES. EXPECT DRY CONDITIONS
ACROSS THE FORECAST AREA ON FRIDAY THANKS TO RIDGING TO THE WEST
AND THE DOWNSLOPE FLOW.
THE WEST TO EAST ORIENTED SURFACE PRESSURE GRADIENT WILL INCREASE
ACROSS WESTERN ZONES OF THE FORECAST AREA FRIDAY NIGHT INTO
SATURDAY. THIS WILL BRING GUSTY WINDS FROM BILLINGS WEST AND
ENHANCED DOWNSLOPE FLOW. EXPECT TEMPERATURES TO CONTINUE TO
RECOVER ON SATURDAY THANKS TO THIS FLOW...BUT THE KLONDIKE NATURE
OF THE CHINOOK AND THE EXPECTED CONTINUED SNOW COVER WILL KEEP
HIGH TEMPERATURES REACHING ONLY AROUND FREEZING ACROSS THE
WESTERN ZONES.
A SHORTWAVE TROUGH IN THE NORTHWESTERLY FLOW WILL APPROACH THE
FORECAST AREA SATURDAY NIGHT INTO SUNDAY. THIS WILL PUSH A SURFACE
LOW OFF THE FRONT RANGE AND BRING A COLD FRONT IN FROM THE NORTH
AS A CANADIAN HIGH PRESSURE SYSTEM BUILD INTO THE AREA. THIS WILL
RETURN TEMPERATURES ON SUNDAY BACK TO BELOW NORMAL VALUES...BUT
WITH 850 MB TEMPERATURES AROUND -5C...SURFACE TEMPERATURES WILL
REMAIN IN THE MID 20S FOR MOST PLACES. THIS SHORTWAVE WILL ALSO
BRING SOME WEAK QG FORCING ACROSS THE AREA DURING THE DAY SUNDAY.
HOWEVER...WITH THE STRENGTHENING DOWNSLOPE NORTHWESTERLY FLOW
BEHIND THE SURFACE LOW...SNOW SHOWERS WILL MAINLY BE CONFINED TO
MOUNTAIN LOCATIONS. DECIDED TO SHOW ONLY SLIGHT CHANCE POPS ACROSS
THE PLAINS AS SNOW SHOWERS ACROSS THE PLAINS SHOULD REMAIN WIDELY
SCATTERED.
FOR MONDAY THROUGH WEDNESDAY...GLOBAL MODEL SOLUTIONS ARE
CONSISTENT WITH BUILDING A HIGH AMPLITUDE RIDGE WEST OF THE
FORECAST AREA WITH NORTHWESTERLY OVERHEAD. HOWEVER...THE MODELS
ARE STRUGGLING WITH THE EXACT PLACEMENT OF THE RIDGE AND THUS ARE
SHOWING WIDE VARIATIONS IN THE HIGH TEMPERATURE FORECASTS FROM RUN
TO RUN. OVERALL THIS WILL BE A DRY PATTERN FOR THE FORECAST AREA
WITH DOWNSLOPE FLOW PREVAILING. BACKDOOR COLD FRONTS WILL BE
POSSIBLE IN THIS PATTERN DEPENDING ON HOW THE DETAILS DEVELOP. FOR
NOW HAVE ELECTED TO RIDE CLOSE TO THE MIDDLE OF THE GUIDANCE
ENVELOPE FOR TEMPERATURES DURING THIS PERIOD UNTIL THE MODELS
BECOME MORE CONSISTENT WITH THE DETAILS. CHURCH
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL THIS MORNING ACROSS ALL TAF SITES. A
WEATHER SYSTEM WILL BRING LOWERING CLOUD DECKS AND SNOW SPREADING
FROM WEST TO EAST DURING THE DAY. EXPECT SNOW TO IMPACT KLVM WITH
MVFR TO IFR CONDITIONS BY LATE WEDNESDAY MORNING. SNOW WILL SPREAD
EAST...BRINGING MVFR TO IFR CONDITIONS TO KBIL AND KSHR BY LATE
AFTERNOON OR EARLY EVENING. KMLS WILL SEE A LOWERING CLOUD DECK
THIS AFTERNOON...BUT LIGHT SNOW BRINGING MVFR/IFR CONDITIONS WILL
NOT BEGIN UNTIL AFTER MIDNIGHT TONIGHT. CHURCH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 014 008/017 006/026 014/033 015/025 011/031 014/034
5/S 87/S 01/E 01/N 22/S 11/B 10/N
LVM 017 009/023 007/025 014/033 015/024 007/027 012/034
6/S 86/S 11/E 11/N 23/S 11/B 11/N
HDN 014 007/016 002/026 011/031 011/025 011/030 014/033
5/S 87/S 11/E 01/B 12/S 11/B 10/B
MLS 009 003/011 903/018 007/026 008/021 011/027 012/029
1/B 66/S 11/E 11/B 12/S 11/B 11/B
4BQ 012 005/013 903/022 007/030 009/023 007/030 011/034
2/S 88/S 31/E 11/B 12/S 11/B 10/B
BHK 008 001/012 904/016 006/024 007/019 009/025 011/027
1/B 67/S 21/E 11/B 12/S 11/B 11/B
SHR 018 008/018 006/028 007/031 007/026 008/030 012/031
4/S 88/S 31/E 01/U 12/S 11/B 10/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
607 AM CST WED DEC 26 2012
.AVIATION...
12Z TAFS FOR KOFK...KOMA AND KLNK.
VFR CONDITIONS ARE EXPECTED THROUGH 27/12Z. AN AREA OF MID LEVEL
CLOUDS WITH BASES OF 7000-10000 FT WILL DRIFT THROUGH EASTERN
NEBRASKA THIS MORNING THEN CLEARING EXPECTED. LIGHT NORTHEAST
WINDS SHOULD SLOWLY TURN TO THE EAST BUT MAY BE VARIABLE DUE TO
THE HIGH PRESSURE AREA IN THE REGION.
NIETFELD
&&
.PREV DISCUSSION... /ISSUED 305 AM CST WED DEC 26 2012/
DISCUSSION...
SNOW AMOUNTS THURSDAY/THURSDAY NIGHT ARE THE MAIN FORECAST FOCUS
AS WEST COAST SYSTEM PROVIDES A PROLONGED PERIOD OF WEAK TO
MODERATE LIFT ACROSS THE AREA. HOW FAR SOUTH WILL THESE MODEST
SNOW AMOUNTS POTENTIALLY EXTEND IS ALSO AN ISSUE. AFTER THIS
SYSTEM DEPARTS...REMAINDER OF FORECAST WILL BE DRY WITH MINOR
TEMPERATURE FLUCTUATIONS.
EARLY MORNING SATELLITE IMAGERY SHOWED FORECAST AREA IN BETWEEN
NRN PLAINS TROUGH/MS VALLEY CLOSED LOW AND APPROACHING BROAD WEST
COAST TROUGH. THUS AFTER A MAINLY EARLY DAY PERIOD OF MID
CLOUDINESS NRN ZONES ALONG WITH PSBL FLURRIES...PTLY/MOSTLY SUNNY
START TO DAY SHOULD BE FOLLOWED BY INCREASING CLOUDS LATER AS
WEST COAST TROUGH SPREADS SOME HIGH CLOUDS AND THEN THICKENING
WARM ADVECTION MID LEVEL CLOUDS TOWARD AND ACROSS THE FORECAST
AREA. BOOSTED SOME TEMPERATURES THIS AFTN...ESPECIALLY NWRN ZONES
WHERE WARM ADVECTION...LATE MORNING/EARLY AFTN SUN AND LESSER
SNOW COVER SUPPORT RAP SFC TEMP FORECAST OF NEAR OR ABOVE 20 F.
WEST COAST SYSTEM HAD DECENT 100+ M HGT FALLS AT H5 FM CNTRL CA
INTO WA LAST EVENING...AND AS IT MOVES ACROSS THE ROCKIES...00Z
NAM/GFS/ECMWF WERE SIMILAR IN CLOSING OFF H7 LOW AND PLACING INTO
CNTRL NEBR JUST WEST OF WCNTRL ZONES AT 00Z FRIDAY. LOW THEN
FORECAST TO SLOWLY LIFT ENE ACROSS NERN NEBR THU NGT ALTHOUGH
MODELS BEGIN DIVERGING ON AMOUNT OF ENERGY/LIFT LAGS BACK. BROAD
WARM ADVECTION...DEPICTED NICELY ON 285K ISENTROPIC SURFACES...SHOULD
BEGIN THICKENING CLOUDS OVER AREA LATE TONIGHT INTO MIDDAY
THURSDAY FOLLOWED BY INCREASING SNOW AREA. APPEARS A GENERAL
0.10-0.20 QPF TOTAL GENERATED BY SREF/NAM/GFS/ECMWF IS
ACCEPTABLE...ALTHOUGH IT WAS NOTED CANADIAN WAS ABOUT DOUBLE THAT
WHICH WOULD POSE MORE PROBLEMS SINCE WITH DEEP COLD AIRMASS IN
PLACE...SNOW TO LIQUID RATIOS COULD BE IN UPPER TEENS TO AROUND 20-1.
QUESTION BECOMES HOW FAR SOUTH WILL THE HIGHER QPF TOTALS EXTEND.
WOULD THINK THEY WOULD BE MOSTLY ALONG AND NORTH OF H7 TRACK WHICH
WOULD PLACE THEM MOSTLY NORTH OF HIGHWAY 30. HOWEVER...STEEP H7-H5
LAPSE RATES WERE NOTED SWRN ZONES THU AFTN AND ALONG KS/MO BORDERS
THU NGT WHICH COULD AID IN SOME SORT OF CONVECTIVE PCPN BANDS
SOUTHERN ZONES. THIS FORECAST WILL INCLUDE AMOUNTS AROUND 2
INCHES NEAR HIGHWAY 30 WITH 3-4 INCHES NORTH OF THERE AND AMOUNTS
LOWERING TO LESS THAN AN INCH SOUTH OF LINCOLN-SWRN IA. NO
HEADLINES YET AS WINDS EXPECTED TO BE MODEST AND THESE TOTALS
EXTEND AT LEAST OVER AN 18 HR PD. INCREASING CLOUDS SHOULD HOLD
TEMPS UP TONIGHT WITH LATE EVENING LOW PROBABLE MOST AREAS...BUT
CLOUDS AND SNOW COULD LIMIT WARMING NRN ZONES SOME DEGREE
THURSDAY.
WITH POTENTIALLY SLOWER DEPARTURE OF UPPER TROUGH...INCREASED SNOW
CHANCES NERN ZONES THU NGT AND EVEN FRIDAY MORNING FAR EAST.
TEMPERATURE PROFILE IN ANY LINGERING MOISTURE+PERSISTENT WEAK
LIFT PER NAM COULD KEEP LIGHT SNOW OR FLURRIES GOING WELL INTO
FRIDAY AND THUS FLURRIES WERE EXTENDED OVER NERN 1/3RD
EVEN FRI AFTN. DELAYED CLEARING SHOULD KEEP DIURNAL TEMPERATURE
RANGE SMALLER AND READINGS WERE ADJUSTED FOR SUCH.
AFTER THAT...AS MENTIONED ABOVE...FORECAST WAS KEPT DRY.
MODERATING TEMPERATURES EXPECTED SATURDAY INTO SUNDAY AS UPPER
RIDGING OCCURS BEFORE FLOW FLATTENS AS NRN STREAM TROUGH
APPROACHES. COULD CONCEIVABLY WARM NICELY SOME AREAS ON SUNDAY
AHEAD OF TROUGH...BUT HELD BACK BY SNOW COVER. NONETHELESS...DID
BOOST READINGS A LITTLE...THE MOST ON SUNDAY ACROSS THE SW. HIGHS
WERE KEPT IN CONSERVATIVE 20S MON/NEW YEARS DAY...BUT PER
ECMWF...ARCTIC AIR MAY REMAIN BOTTLED UP FARTHER NORTH THAN
THE FORECAST AREA.
CHERMOK
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1056 AM EST WED DEC 26 2012
.SYNOPSIS...
LOW PRESSURE MOVING ACROSS TO THE NORTHWEST WILL PUSH A WARM FRONT
ACROSS THE AREA FROM THE SOUTH THIS MORNING...AND THEN A COLD FRONT
FROM THE WEST THIS EVENING. HIGH PRESSURE WILL BUILD ACROSS FROM THE
WEST THURSDAY AND FRIDAY. ANOTHER COMPLEX FRONTAL SYSTEM WILL AFFECT
THE AREA SATURDAY AND SATURDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 10 AM WED...A POTENT STORM SYSTEM WILL CONTINUE TO IMPACT
ERN NC THIS AFTERNOON AND A TORNADO WATCH HAS BEEN ISSUED THROUGH
5 PM THIS EVENING. A WARM FRONT IS JUST BEGINNING TO PUSH INLAND
FROM CAPE HATTERAS THROUGH JACKSONVILLE AND HRRR PROGS IT TO PUSH
TO AROUND THE I-95 CORRIDOR BY AROUND NOON TO 1 PM. THIS WILL
PLACE ERN NC IN THE WARM SECTOR OF THE SYSTEM BRINGING INCREASED
INSTABILITY AND SEVERE WEATHER THREAT. TREMENDOUS HELICITY IS IN
PLACE ACROSS THE REGION WITH MODIFIED KMHX 12Z SOUNDING INDICATING
OVER 700 M2/S2 0-3KM SRH AS WELL AS MODERATE INSTABILITY AROUND
600 J/KG ONCE WE MOVE INTO THE WARM SECTOR AND TEMPS CLIMB INTO
THE M/U60S. SEVERAL CELLS ALREADY HAVE BEEN SHOWING SIGNS OF
ROTATION AND THROUGH THE LATE MORNING INTO THE AFTERNOON WILL BE
WATCHING FOR DISCRETE SUPERCELL POSSIBLE BRINGING TORNADOES AND
DAMAGING WINDS...WHICH WILL POTENTIALLY BE FOLLOWED BY A
STRENGTHENING QLCS AHEAD OF THE COLD FRONT WITH BOWING SEGMENTS
POTENTIALLY BRINGING SEVERE WIND GUSTS AND TORNADOES. HRRR PROGS
THIS LINE TO PUSH INTO WESTERN SECTIONS OF THE CWA AROUND 1-2
PM...THEN PUSH OFF THE COAST AROUND 6-7PM.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
AS OF 400 AM WED...COLD FRONT AND BACK EDGE OF SHRA/TSTMS EXPECTED
TO BE NEAR COAST AT BEGINNING OF PERIOD AND OFFSHORE BY LATE
EVENING...AND CONTINUED PREVIOUS FCST POPS. SOME DECREASE IN CLOUDS
WILL FOLLOW FRONTAL PASSAGE BUT WHOLESALE CLEARING WILL BE DELAYED
UNTIL PASSAGE OF UPR TROF TOWARD THU MORNING. GUSTY WINDS WILL
CONTINUE OVERNIGHT WITH DEEPENING LOW PRES MOVING OFF MID ATLC
COAST...AND CONTINUED WIND ADVSY FOR COASTAL SECTIONS.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
COOLER/DRIER WEATHER FOLLOWS COLD FRONTAL PASSAGE FOR THURSDAY
AND CONTINUING INTO FRIDAY. CIRCULATION AROUND DEPARTING LOW
PRESSURE WILL KEEP BREEZY/WINDY CONDITIONS GOING INTO THURSDAY
THEN DECREASING WINDS AS HIGH PRESSURE BUILDS INTO THE AREA THU
NIGHT AND FRIDAY. HIGH TEMPS BOTH THU AND FRI UNIFORMLY WITHIN A
FEW DEGS OF 50F. WITH LOWS THU NIGHT DIPPING INTO THE UPPER 20S
(30S COAST) UNDER GOOD RADIATIONAL COOLING.
THE PATTERN BECOMES MORE ACTIVE AND COMPLEX EARLY IN THE WEEKEND
AS THE NEXT PROGRESSIVE AND POTENT SHORTWAVE MOVES ACROSS THE
AREA. AT THE SURFACE A COASTAL WARM FRONT WILL NEGATIVE TILT UPPER
TROF WILL MOVE RAPIDLY NE FROM THE TN VALLEY MOVE INTO COASTAL
SECTIONS WHILE LOW PRESSURE DEVELOPS ALONG IT JUST OFF OF THE
COAST. THIS LOW WILL DEEPEN RAPIDLY AS IT MOVES NE ALONG OR JUST OFF
THE COAST SATURDAY AFTERNOON AND EVENING BEFORE MOVING OFF TO THE
NE SATURDAY NIGHT. SHOWERS ARE EXPECTED TO DEVELOP LATE FRIDAY
NIGHT AND CONTINUE FOR MUCH OF SATURDAY BEFORE ENDING SATURDAY
EVENING. IT WILL AGAIN BE TURNING SHARPLY COLDER AND WINDY
SATURDAY NIGHT AND SUNDAY. POSSIBLE WIDE RANGE IN HIGH TEMPERATURES
SATURDAY WITH LOWER 60S COAST AND UPPER 40S DEEP INLAND. ON
SUNDAY HIGHS ARE FORECAST TO ONLY BE IN THE MIDDLE TO UPPER 40S
AREA WIDE. FAIR CONDITIONS WILL BE FORECAST MONDAY WITH HIGH
PRESSURE OVER THE AREA THEN MOISTURE ROUNDING A BUILDING UPPER
RIDGE OVER THE SOUTHEAST COULD BRING SOME RAIN TO THE AREA
TUESDAY. TEMPERATURES REMAIN BLO NORMAL EARLY NEXT WEEK.
&&
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /THROUGH 12Z THURSDAY/...
AS OF 1030 AM WED...IFR CIGS ACROSS RTES THIS MORNING WITH PERIODS
OF HEAVY RAIN. A WARM FRONT WILL BE LIFTING ACROSS THE REGION OVER
THE NEXT COUPLE HOURS WITH WINDS SHIFTING TO SLY GUSTING AROUND 25
KT AND COULD SEE CIGS LIFT TO MVFR OUTSIDE OF HEAVIER SHOWERS.
DISCRETE SUPERCELLS WILL CONTINUE TO IMPACT THE REGION THIS
AFTERNOON AND COULD SEE DAMAGING WIND GUSTS AND ISOLATED
TORNADOES. A STRONG SQUALL LINE IS THEN EXPECTED TO PUSH THROUGH
AROUND 18-22Z THIS AFTERNOON AHEAD OF A COLD FRONT WHICH WILL
BRING A CONTINUED THREAT OF DAMAGING WIND GUSTS AND TORNADOES.
LONG TERM /THURSDAY THROUGH SUNDAY/...
VFR EXPECTED THROUGH FRIDAY AS HIGH PRESSURE MOVES OVER THE AREA
HOWEVER GUSTY WEST WINDS WILL PREVAIL OVER THE TERMINALS ON THU.
RAIN AND SUB VFR CONDITIONS WILL DEVELOP LATE FRI NIGHT OR EARLY
SATURDAY AND PERSIST THROUGH SATURDAY EVENING. ALTHOUGH VFR
CONDITIONS SHOULD DEVELOP SATURDAY NIGHT AND SUNDAY STRONG NW
WINDS ARE EXPECTED BEHIND A DEPARTING STRONG COASTAL LOW.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 700 AM WED...WARM FRONT CONTINUING TO APPROACH FROM S WITH
WINDS AROUND TO SE AT BUOY 41036 THIS HOUR. FCST ON TRACK WITH GALE
FORCE SRLY WINDS EXPECTED TO DEVELOPE THIS AFTN.
/PREVIOUS DISCUSSION/
AS OF 400 AM WED...NO SIGNIFICANT CHANGES TO PREVIOUS FCST. E-NE
WINDS HAVE INCREASED TO 15-25 KT OVERNIGHT WITH TIGHTENING PRES GRAD
IN ADVANCE OF WARM FRONT APPROACHING FROM S AND LOW PRES MOVING INTO
ERN TN. AS LOW CONTINUES MOVING NE...WARM FRONT WILL LIFT N OVER
AREA THIS MORNING WITH WINDS BECOMING SRLY AND INCREASING TO GALE
FORCE IN FREQUENT GUSTS BY EVENING. COLD FRONT WILL MOVE ACROSS AREA
THIS EVENING. WINDS WILL BECOME SW-W FOLLOWING FRONTAL PASSAGE BUT
REMAIN STRONG AND GUSTY AS LOW PRES MOVES OFF MID ATLC COAST
OVERNIGHT.
WW3 UNDERDONE WITH SEAS EARLY THIS MORNING DUE TO STRONGER
WINDS...AND HAVE ADJUSTED SEAS ACCORDINGLY FOR THIS MORNING. REST OF
PERIOD MORE REASONABLE WITH SEAS EXPECTED TO BUILD TO 8-13 FT WITH
GALE FORCE WINDS.
STRONG WINDS MAY ALSO BRING MINOR COASTAL FLOODING UP TO 2 FT TO THE
SOUND SIDE OBX AND LOW WATER ACROSS THE LOWER PORTIONS OF THE NEUSE
AND PAMLICO RIVERS BEGINNING LATE TODAY INTO THURSDAY...BUT NOT
ENOUGH CONFIDENCE FOR ANY ADVISORIES AS THIS TIME.
LONG TERM /THURSDAY THROUGH SUNDAY/...
GALE WARNINGS WILL CONTINUE FOR MUCH OF THE MARINE AREA INTO
THURSDAY BEHIND THE STRONG COLD FRONT WITH DIMINISHING WINDS LATE
THURSDAY AND THURSDAY NIGHT. SEAS WILL BE SUBSIDING DUE TO
OFFSHORE WIND TRAJECTORY WITH SEAS FALLING BELOW 6 FT ALL AREAS BY
LATE THU NIGHT OR EARLY FRIDAY AS HIGH PRESSURE BRIEFLY BUILDS
OVER THE WATERS. THE BENIGN CONDITIONS WILL BE SHORT LIVED THOUGH
AS THE NEXT POTENT SHORTWAVE LEADS TO STRONG CYCLOGENESIS OFF THE
NC COAST SATURDAY AND SATURDAY EVENING. FOR NOW WILL FORECAST
SMALL CRAFT ADVISORY CONDITIONS REDEVELOPING BUT COULD SEE ANOTHER
PERIOD OF GALES WITH DOUBLE DIGIT SEA HEIGHTS ESPECIALLY SATURDAY
NIGHT INTO SUNDAY.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...WIND ADVISORY UNTIL 4 PM EST THURSDAY FOR NCZ046-047-081-095-
103-104.
MARINE...GALE WARNING FROM 4 PM THIS AFTERNOON TO 11 AM EST THURSDAY
FOR AMZ135-150.
SMALL CRAFT ADVISORY UNTIL 4 PM EST THURSDAY FOR AMZ130.
GALE WARNING UNTIL 4 PM EST THURSDAY FOR AMZ152-154.
GALE WARNING UNTIL 11 AM EST THURSDAY FOR AMZ156-158.
&&
$$
SYNOPSIS...JBM
NEAR TERM...SK
SHORT TERM...JBM
LONG TERM...BTC/JME
AVIATION...JBM/BTC
MARINE...JBM/BTC
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1004 AM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO
TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE
OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID-ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
930AM UPDATE TO ADD FREEZING RAIN MENTION SOUTHERN BORDER ZONES PER
RECENT REPORTS.
A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN
VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A
NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL
APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY
THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT
WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM
SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE
APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY
LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT
AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS.
RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH
THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF
10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM.
THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT
AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS
PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE
SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE
XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A
MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO
REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND
NRN TIER ZONES BY LATE MORNING/EARLY AFTN.
THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS
FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS
LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED
TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE
SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY
WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL.
COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU
END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND
N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE
PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE
CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE
HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN
SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA
MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST
SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD
BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO
SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL
BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS.
HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS
STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE
ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF
THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS.
DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM
WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE
REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR
POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY
MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR
DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES
COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT
NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT
WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO
EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA
MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF
FZDZ.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT
MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE
NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD
ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN
MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF
LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS
MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL
FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI
AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL
WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM
EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION.
CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF
PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND
COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW
00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW
LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS
ON DAY 4/SAT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD
OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV.
CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE
PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST.
WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND
BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA
EXPECTED THIS AFTERNOON AND EVENING.
TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH
FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST.
18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA
MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT.
POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST
CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING.
ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER
LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS
IN THE 1-4KFT LEVELS.
SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST
OVERNIGHT INTO EARLY THURDAY. ELSEWHERE CONDITIONS SHOULD RISE TO
MVFR AT TIMES BEFORE 12Z THURSDAY.
IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND
BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST
MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH
MOUNTAIN AND LAKE ENHANCED SNOWSHOWERS.
IMPROVING CONDTIONS EXPECTED THURSDAY NIGTH INTO FRIDAY.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF
THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ004>006-010>012-037-041-042.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019-
026>028-045-046-049>053-058.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025-
033>035.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...ROSS/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...GRUMM/CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
933 AM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO
TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE
OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID-ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
930AM UPDATE TO ADD FREEZING RAIN MENTION SOUTHERN BORDER ZONES PER
RECENT REPORTS.
A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN
VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A
NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL
APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY
THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT
WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM
SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE
APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY
LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT
AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS.
RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH
THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF
10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM.
THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT
AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS
PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE
SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE
XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A
MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO
REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND
NRN TIER ZONES BY LATE MORNING/EARLY AFTN.
THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS
FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS
LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED
TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE
SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY
WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL.
COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU
END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND
N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE
PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE
CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE
HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN
SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA
MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST
SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD
BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO
SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL
BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS.
HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS
STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE
ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF
THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS.
DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM
WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE
REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR
POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY
MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR
DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES
COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT
NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT
WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO
EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA
MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF
FZDZ.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT
MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE
NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD
ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN
MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF
LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS
MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL
FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI
AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL
WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM
EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION.
CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF
PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND
COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW
00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW
LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS
ON DAY 4/SAT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
ONLY IFR CIGS ARE AT BFD AND JST AS THE LOW STRATOCU HANGS AROUND
THIS MORNING. A LARGE UPPER LEVEL LOW CONTINUES TO MAKE IT/S WAY
NORTHEAST TODAY WHICH WILL BRING A SIGNIFICANT WINTER STORM. CIGS
MAY SLIP TO VFR FOR A COUPLE OF HOURS LATE THIS MORNING...THOUGH
EXPECT THAT JST AND BFD REMAIN IFR OR LOWER THROUGH THIS
TIMEFRAME. CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS SNOW
ARRIVES IN KJST AROUND 13Z.
SNOW SHOULD ARRIVE AT AOO AROUND 14Z...KBFD-KUNV-KMDT AROUND
16Z...AND KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF
SITES TO IFR WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A
FACTOR AS SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB.
STILL LOOKS LIKE A LAYER OF WARMER AIR TRIES TO WORK IN FROM THE
SOUTH THIS AFTERNOON AND EVENING...ICING WILL BECOME A CONCERN. A WINTRY
MIX AND/OR FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED
EVE.
MDT AND LNS SHOULD SEE RAIN AFTER 00Z THIS EVENING AS THOSE
LOCATIONS WILL REMAIN IN THE WARM SECTOR. HEAVY PRECIP BEGINS TO
END FROM W TO E FROM 04-10Z THU...BUT LOWER CLOUDS WILL LINGER
THROUGH 12Z TOMORROW MORNING.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF
THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ004>006-010>012-037-041-042.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019-
026>028-045-046-049>053-058.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025-
033>035.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...ROSS/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
910 AM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO
TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE
OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID-ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
QUICK UPDATE TO BRING LANCASTER AND YORK INTO THE ADVISORY. PRECIP
STARTING AS SNOW THERE AND EXPECT SOME ACCUMULATIONS BEFORE
CHANGEOVER OCCURS.
A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN
VALLEY EARLY THIS MORNING PER LATEST WV SATL LOOP WILL TAKE ON A
NEGATIVE TILT AS IT ACCELERATES NEWD AND CROSSES THE CENTRAL
APPALACHIANS THIS EVENING BEFORE REACHING THE DELMARVA REGION BY
THE END OF THE PERIOD. THE LATEST GUIDANCE IS IN GOOD AGREEMENT
WITH THE EVOLUTION OF THIS SIGNIFICANT WINTER STORM
SYSTEM...SHOWING THE PRIMARY SFC LOW TRACKING ALONG/WEST OF THE
APPLCHNS SPINE FM CNTRL TN/KY INTO SRN WV. MEANWHILE...A SECONDARY
LOW WILL FORM BY LATE THIS AFTN OR EARLY EVE IN THE NC/VA PIEDMONT
AND SHIFT NEWD ACRS CHESAPEAKE BAY TO NJ BY 12Z THURS.
RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH
THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF
10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM.
THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT
AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS
PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE
SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE
XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A
MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO
REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND
NRN TIER ZONES BY LATE MORNING/EARLY AFTN.
THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS
FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS
LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED
TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE
SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY
WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL.
COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU
END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND
N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE
PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE
CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE
HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN
SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA
MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST
SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD
BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO
SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL
BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS.
HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS
STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE
ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF
THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS.
DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM
WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE
REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR
POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY
MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR
DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES
COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT
NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT
WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO
EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA
MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF
FZDZ.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT
MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE
NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD
ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN
MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF
LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS
MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL
FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI
AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL
WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM
EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION.
CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF
PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND
COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW
00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW
LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS
ON DAY 4/SAT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
ONLY IFR CIGS ARE AT BFD AND JST AS THE LOW STRATOCU HANGS AROUND
THIS MORNING. A LARGE UPPER LEVEL LOW CONTINUES TO MAKE IT/S WAY
NORTHEAST TODAY WHICH WILL BRING A SIGNIFICANT WINTER STORM. CIGS
MAY SLIP TO VFR FOR A COUPLE OF HOURS LATE THIS MORNING...THOUGH
EXPECT THAT JST AND BFD REMAIN IFR OR LOWER THROUGH THIS
TIMEFRAME. CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS SNOW
ARRIVES IN KJST AROUND 13Z.
SNOW SHOULD ARRIVE AT AOO AROUND 14Z...KBFD-KUNV-KMDT AROUND
16Z...AND KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF
SITES TO IFR WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A
FACTOR AS SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB.
STILL LOOKS LIKE A LAYER OF WARMER AIR TRIES TO WORK IN FROM THE
SOUTH THIS AFTERNOON AND EVENING...ICING WILL BECOME A CONCERN. A WINTRY
MIX AND/OR FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED
EVE.
MDT AND LNS SHOULD SEE RAIN AFTER 00Z THIS EVENING AS THOSE
LOCATIONS WILL REMAIN IN THE WARM SECTOR. HEAVY PRECIP BEGINS TO
END FROM W TO E FROM 04-10Z THU...BUT LOWER CLOUDS WILL LINGER
THROUGH 12Z TOMORROW MORNING.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF
THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ004>006-010>012-037-041-042.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019-
026>028-045-046-049>053-058.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025-
033>035.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...ROSS/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
758 AM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO
TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE
OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID-ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN VALLEY EARLY THIS
MORNING PER LATEST WV SATL LOOP WILL TAKE ON A NEGATIVE TILT AS IT
ACCELERATES NEWD AND CROSSES THE CENTRAL APPALACHIANS THIS EVENING
BEFORE REACHING THE DELMARVA REGION BY THE END OF THE PERIOD. THE
LATEST GUIDANCE IS IN GOOD AGREEMENT WITH THE EVOLUTION OF THIS
SIGNIFICANT WINTER STORM SYSTEM...SHOWING THE PRIMARY SFC LOW
TRACKING ALONG/WEST OF THE APPLCHNS SPINE FM CNTRL TN/KY INTO SRN
WV. MEANWHILE...A SECONDARY LOW WILL FORM BY LATE THIS AFTN OR
EARLY EVE IN THE NC/VA PIEDMONT AND SHIFT NEWD ACRS CHESAPEAKE BAY
TO NJ BY 12Z THURS.
RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH
THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF
10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM.
THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT
AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS
PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE
SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE
XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A
MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO
REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND
NRN TIER ZONES BY LATE MORNING/EARLY AFTN.
THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS
FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS
LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED
TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE
SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY
WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL.
COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU
END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND
N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE
PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE
CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE
HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN
SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA
MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST
SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD
BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO
SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL
BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS.
HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS
STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE
ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF
THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS.
DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM
WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE
REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR
POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY
MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR
DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES
COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT
NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT
WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO
EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA
MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF
FZDZ.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT
MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE
NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD
ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN
MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF
LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS
MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL
FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI
AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL
WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM
EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION.
CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF
PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND
COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW
00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW
LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS
ON DAY 4/SAT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
ONLY IFR CIGS ARE AT BFD AND JST AS THE LOW STRATOCU HANGS AROUND
THIS MORNING. A LARGE UPPER LEVEL LOW CONTINUES TO MAKE IT/S WAY
NORTHEAST TODAY WHICH WILL BRING A SIGNIFICANT WINTER STORM. CIGS
MAY SLIP TO VFR FOR A COUPLE OF HOURS LATE THIS MORNING...THOUGH
EXPECT THAT JST AND BFD REMAIN IFR OR LOWER THROUGH THIS
TIMEFRAME. CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS SNOW
ARRIVES IN KJST AROUND 13Z.
SNOW SHOULD ARRIVE AT AOO AROUND 14Z...KBFD-KUNV-KMDT AROUND
16Z...AND KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF
SITES TO IFR WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A
FACTOR AS SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB.
STILL LOOKS LIKE A LAYER OF WARMER AIR TRIES TO WORK IN FROM THE
SOUTH THIS AFTERNOON AND EVENING...ICING WILL BECOME A CONCERN. A WINTRY
MIX AND/OR FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED
EVE.
MDT AND LNS SHOULD SEE RAIN AFTER 00Z THIS EVENING AS THOSE
LOCATIONS WILL REMAIN IN THE WARM SECTOR. HEAVY PRECIP BEGINS TO
END FROM W TO E FROM 04-10Z THU...BUT LOWER CLOUDS WILL LINGER
THROUGH 12Z TOMORROW MORNING.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF
THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ004>006-010>012-037-041-042.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ017>019-
026>028-045-046-049>053-058.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025-
033>035.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
648 AM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO
TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE
OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID-ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
A POWERFUL CLOSED LOW MOVING INTO THE LWR OH/TN VALLEY EARLY THIS
MORNING PER LATEST WV SATL LOOP WILL TAKE ON A NEGATIVE TILT AS IT
ACCELERATES NEWD AND CROSSES THE CENTRAL APPALACHIANS THIS EVENING
BEFORE REACHING THE DELMARVA REGION BY THE END OF THE PERIOD. THE
LATEST GUIDANCE IS IN GOOD AGREEMENT WITH THE EVOLUTION OF THIS
SIGNIFICANT WINTER STORM SYSTEM...SHOWING THE PRIMARY SFC LOW
TRACKING ALONG/WEST OF THE APPLCHNS SPINE FM CNTRL TN/KY INTO SRN
WV. MEANWHILE...A SECONDARY LOW WILL FORM BY LATE THIS AFTN OR
EARLY EVE IN THE NC/VA PIEDMONT AND SHIFT NEWD ACRS CHESAPEAKE BAY
TO NJ BY 12Z THURS.
RADAR IMAGERY SHOWS THE LEADING EDGE OF THE PCPN SHIELD ASSOC WITH
THE EVOLVING WINTER STORM HAS MOVED INTO SOMERSET COUNTY AS OF
10Z...AND SHOULD REACH THE JOHNSTOWN-ALTOONA AREA AROUND 6 AM.
THE FASTER GFS APPEARS TO BE VERIFYING BETTER WITH THE CURRENT
AREA OF WAA PCPN MOVG QUICKLY NEWD TWD THE MASON-DIXON LINE. AS
PCPN OVERSPREADS LAUREL HIGHLANDS AND S-CNTRL MTNS FROM THE
SW...EXPECT THE DOMINANT PTYPE TO BE SNOW WITH FZRA PSBL OVER THE
XTRME SW RIDGES IN SOMERSET CO WHERE RUC LLVL TEMP DATA SHOWS A
MODEST WARM LYR AT 850MB EXTENDING NEWD FM NRN WV. EXPECT SNOWS TO
REACH THE CENTRAL COUNTIES DURING THE MID-LATE MORNING HOURS AND
NRN TIER ZONES BY LATE MORNING/EARLY AFTN.
THE TRACK OF THE H85-H7 LOW /FM CNTRL KY-TN OVR THE DELMARVA/ IS
FAVORABLE SIGNIFICANT SNOWS OVER MOST OF THE AREA. HEAVY SNOW IS
LKLY IN THE WELL-DEFINED DEFORMATION/COMMA-HEAD PCPN BAND EXPECTED
TO PIVOT OVER N-CNTRL PA LATE THIS AFTN INTO THE EVE. BOTH THE
SREF AND GEFS MEAN SHOW A 5 TO 6 SIGMA 850MB EASTERLY U-WIND ANOMALY
WHICH IS A CLASSIC SYNOPTIC FRONTAL-TYPE HEAVY PCPN SIGNAL.
COMBINE THE PATTERN WITH SOME PTYPE/THERMAL PROBABILITIES AND YOU
END UP WITH A HIGH CONFIDENCE FCST FOR HEAVY SNOW OVER THE NW AND
N-CNTRL MTNS. THE TRICKY PART OF THE FCST CONTINUES TO INVOLVE
PTYPES OVR THE CENTRAL ZONES FROM THE LAUREL HIGHLANDS INTO THE
CENTRAL MTNS AND RIDGE-VALLEY REGION. ALTHOUGH THE LATEST GUIDANCE
HAS TRENDED SLIGHTLY WARMER ALONG THE SRN EDGES OF THE PCPN
SHIELD /AS NOTED BY HPC WWD DISCUSSION/...STILL FEEL THAT FZRA
MAY BE OVERDONE ESP OVER THE INTERIOR SXNS OF THE CWA AS FCST
SOUNDINGS ONLY SHOW A WEAK WARM INTRUSION AROUND H8 WHICH SHOULD
BE OVERCOME BY WET-BULB EFFECTS. THIS FAVORS A BRIEF TRANSITION TO
SNOW/SLEET AS OPPOSED TO FZRA. THE EXPECTED WINTRY MIX WILL STILL
BE SOMEWHAT PROBLEMATIC REGARDING FINAL SNOW ACCUMULATIONS.
HOWEVER STILL FELT COMFORTABLE ADDING AN INCH OR SO TO PREVIOUS
STORM TOTALS ESPECIALLY NORTH OF I-80. MINOR TO MODERATE ICE
ACCUMS ARE EXPECTED FROM THE LAURELS ENEWD ACRS THE PORTIONS OF
THE S-CNTRL MTNS INTO THE NE MTNS/SRN POCONOS.
DID NOT CHANGE THE CONFIGURATION OR TIMING OF THE WINTER STORM
WARNING/ADVY. FOR ADDITIONAL DETAILS ON THE WINTER STORM PLEASE
REFER TO PHLWSWCTP. WILL NEED TO WATCH LANCASTER-YORK COUNTIES FOR
POSSIBLE SHORT-DURATION ADVY AS CONDITIONS TRANSITION FROM WINTRY
MIX TO RAIN BY MAINLY RAIN BY TONIGHT. FOLLOWED HPC CLOSELY FOR
DAY 1 QPF AMTS. 24-HR STORM TOTALS ENDING 12Z THURS OF 1.5 INCHES
COULD CREATE MINOR FLOODING ON THE LOWER MAINSTEM SUSQ TRIBS...BUT
NOT ENOUGH CONFIDENCE AT THIS POINT TO POST A FLOOD WATCH. EXPECT
WINTRY PRECIP TO TAPER OFF FROM SOUTH TO NORTH LATE TONIGHT INTO
EARLY THURS MORNING. AS THE STORM SYSTEM MOVES AWAY FROM THE AREA
...MID-LVL DRYING AND MODEL SOUNDING CONSENSUS SUPPORTS AREAS OF
FZDZ.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT
MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE
NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD
ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN
MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF
LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS
MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL
FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI
AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL
WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM
EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION.
CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF
PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND
COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW
00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW
LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS
ON DAY 4/SAT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
GENERALLY MVFR CIGS ACROSS CENTRAL PA OVERNIGHT AS FLOW TURNS
EASTERLY...KEEPING STRATOCU TRAPPED IN INVERSION AROUND EDGES OF
RETREATING HIGH PRESSURE AREA.
AS SIGNIFICANT WINTER STORM APPROACHES FROM THE SW FOR WED...CIGS
MAY SLIP TO VFR FOR A COUPLE OF HOURS BEFORE ONSET OF PRECIP
/10Z-16Z/. BUT CONDITIONS WILL QUICKLY DEGRADE FROM SW TO NE AS
SNOW ARRIVES IN KJST AROUND 11Z...KBFD-KUNV-KMDT AROUND 14-16Z...AND
KIPT BY 17Z...REDUCING FLIGHT CATEGORIES AT ALL TAF SITES TO IFR
WITHIN AN HOUR OR TWO. WIND SHEAR WILL BECOME A FACTOR AS
SOUTHEASTERLY WINDS INCREASE TO 40-55KTS AT 850MB.
AS LAYER OF WARMER AIR TRIES TO WORK IN FROM THE SOUTH WED
AFT/EVE...ICING WILL BECOME A CONCERN. A WINTRY MIX AND/OR
FREEZING RAIN WILL IMPACT SOUTHERN/EASTERN SECTIONS WED EVE.
HEAVY PRECIP BEGINS TO END FROM W TO E FROM 04-10Z THU...BUT
LOWER CLOUDS WILL LINGER.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
MINOR FLOODING MAY RESULT ON THE LOWER SUSQ TRIBS...SINCE MOST OF
THE 1.5 INCH QPF SHOULD BE RAIN SOUTH/EAST OF HARRISBURG.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ004>006-010>012-037-041-042.
WINTER STORM WARNING FROM 10 AM THIS MORNING TO 7 AM EST
THURSDAY FOR PAZ017>019-026>028-045-046-049>053-058.
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ024-025-
033>035.
WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 7 AM EST
THURSDAY FOR PAZ036-056-057-059-063-064.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...CERU
HYDROLOGY...STEINBUGL
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
112 PM EST WED DEC 26 2012
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL TRACK FROM THE TENNESSEE
VALLEY ACROSS THE MID ATLANTIC TODAY...WITH THE ASSOCIATED COLD
FRONT PUSHING OFF THE COAST BY EARLY THURSDAY MORNING. HIGH
PRESSURE RETURNS THURSDAY AFTERNOON THROUGH FRIDAY. ANOTHER LOW
PRESSURE SYSTEM WILL AFFECT THE REGION ON SATURDAY.
&&
.NEAR TERM /UNTIL 10 PM THIS EVENING/...
UPDATE...WARM FRONT IS CURRENTLY DRAPED OVER CAPE HATTERAS DOWN
INTO NW SC EARLY THIS AFTN AND IS SLOW TO LIFT NWD. OVERALL...
THE LOCATION OF THE WARM FRONT IS MORE IN-LINE WITH RUC13 MODEL
SOLUTIONS. BEST CONVECTION/LIGHTNING HAS BEEN OBSERVED RIGHT ALONG
THIS BOUNDARY AND IS EXPECTED TO MOVE UP INTO NE NC AND FAR SE VA
BY LATE AFTN/EARLY EVENING. PLACEMENT OF THE WARM FRONT WILL BE
CRUCIAL IN DETERMINING GREATEST THUNDERSTORM THREAT THROUGH THE
REMAINDER OF THIS AFTN/EARLY EVENING.
MODEL SOUNDINGS FOR KECG HINTED AT BRIEF LLVL DRYING DEVELOPING
DURING THIS AFTN BEFORE THE ATMOSPHERIC PROFILE BECOMES FULLY
SATURATED AGAIN. IF THIS DRYING IS REALIZED...THEN THIS WOULD
SUPPORT STRONG AND POTENTIALLY DAMAGING THUNDERSTORM WIND GUSTS IN
THE NE NC AND FAR SE VA VICINITIES. THIS PARTICULAR REGION ALSO
SITS WITHIN FAVORABLE VEERING WIND SHEAR PROFILES (20-25 KT SE SFC
WINDS VEERING TO SW 45-70 KT ALOFT)...WHICH ALSO SUPPORTS ISOLATED
TORNADO/WATERSPOUT POTENTIAL AS WELL AS . LATEST RADAR
RETURNS/OBSERVATIONS DO SHOW A SMALL AREA OF LITTLE TO NO PRECIP
AHEAD OF A MORE ORGANIZED CONVECTIVE LINE OF SHOWERS ASSOCIATED
WITH THE SFC COLD FRONT...THUS SUPPORTING THE AFOREMENTIONED
ASSESSMENT. WILL THEREFORE CONTINUE ENHANCED WORDING FOR STRONG TO
SEVERE THUNDERSTORMS IN FAR SE CWA COUNTIES INTO EARLY THIS
EVENING WHERE SPC CONTINUES ITS SLIGHT RISK AREA.
PREVIOUS DISCUSSION (702 AM EST)...LATEST WX ANALYSIS DEPICTS A
~995 MB SFC LOW CENTERED ACRS ERN TENNESSEE...AND A ~1032 MB SFC
HIGH PRESSURE NORTH OF THE CENTRAL GREAT LAKES. TEMPS ARE STILL
ABOVE FREEZING OVER ALL OF THE CWA...EVEN IN THE PIEDMONT...BUT
OBS HAVE REPORTED LIGHT SNOW AND/OR SLEET AT LKU/CHO AND NHK.
INITIAL BATCH OF STEADIER MODERATE PRECIP IS NOW LIFTING OFF TO
THE NE OF RICHMOND...WITH LIGHTER MORE SPOTTY PRECIP ALLOWING FOR
RAIN TO MIX BACK IN AT LKU/CHO. HAVE ADJUSTED FCST FOR CURRENT
CONDITIONS...BUT LITTLE CHANGE IN OVERALL THINKING FOR TODAY...AS
PRECIP RATES INCREASE THERE IS STILL THE POTENTIAL FOR MIXED
SNOW/SLEET OVER FAR NORTHERN TIER OF CWA THROUGH 15Z...BECOMING
CONFINED TO WRN LOUISA/FLUVANNA 15Z-17Z AND THEN SHOULD BE ALL
RAIN THEREAFTER. LITTLE TO NO ACCUMULATION (IF THERE IS ANY
ACCUMULATION IT SHOULD BE LIGHT AND LIMITED TO GRASSY SURFACES
OVER WRN LOUISA/FLUVANNA...NOT CLOSE TO ENOUGH FOR AN ADSY).
THE OTHER CONCERN TODAY IS POTENTIAL FOR SEVERE WX. SPC HAS MUCH
OF THE CWA OUTLINED IN SLIGHT RISK FOR SEVERE THIS AFTN/EARLY
EVENING. BASED ON WHAT OCCURRED YESTERDAY IN THE DEEP SOUTH
(LIGHTNING STRIKES OCCURRING WHERE LI`S HAVE BEEN +5 OR GREATER...
BUT WITH NEGATIVE SHOWALTER INDICES (ELEVATED INSTABILITY)...HAVE
EXTENDED CHC FOR TSTMS LATER THIS AFTN/EARLY EVENING A BIT FARTHER
NORTH TO INCLUDE MUCH OF CENTRAL VA/METRO RICHMOND. STRONG 0-6 KM
BULK SHEAR (60-80 KT) WILL BE CROSSING THE AREA AFTER 18Z...AND
THIS SHOULD BE ENOUGH TO GENERATE AT LEAST SOME EMBEDDED TSTMS
EVEN WITH NO SFC BASED CAPES. HAVE FOCUSED CHC TSTMS FROM 2 PM-6
PM WELL NORTH OF WHERE THE LOW LEVEL INSTABILITY IS FORECAST TO
OCCUR..FOLLOWING CLOSE TO RAP NEGATIVE SHOWALTER INDICES. WITH
THAT SAID...THINK THE CHC FOR SEVERE TSTMS WILL BE MUCH FARTHER
SOUTH...CONFINED TO AREAS WHERE DEW PTS GET INTO THE MID 50S OR
HIGHER AND TEMPS REACH 60 F OR HIGHER. LOOKING AT SPC STORM
REPORTS...THIS IS WHAT HAS HAPPENED THUS FAR. THIS TRANSLATES TO
BEST POTENTIAL FOR SEVERE WX OVER FAR SE/SRN VA AND NE NC. HAVE
MENTIONED THIS IN THE HWO AND HAVE ENHANCED WORDING IN THE GRIDDED
FCST FOR FAR SE VA/NE NC.
OVERALL...RAINFALL RATES ACROSS THE AREA WILL BECOME MODERATE TO
OCCASIONALLY HEAVY AHEAD OF/WITH THE COLD FRONTAL PASSAGE THIS
AFTN/EVENING. PRECIP TOTALS THROUGH TONIGHT/THU RANGE FROM 1.25
TO 1.75 INCHES (WHERE HIGHER AMTS WILL BE LOCATED ALONG THE
IMMEDIATE COAST). SOME AREAS COULD SEE LOCALLY HIGHER AMTS.
HIGHS AROUND 40 EXTREME NW TO THE LWR-MID 60S FAR SE VA AND
POSSIBLY INTO THE UPPER 60S IN NE NC.
&&
.SHORT TERM /10 PM THIS EVENING THROUGH FRIDAY/...
STRONG SFC LOW WILL LIFT NE OF THE AREA LATE TONIGHT INTO EARLY THU
MORNING...WITH THE TRAILING UPPER LOW MOVING ACROSS NRN VA/SE MD
AND DE. WILL LINGER POPS ACROSS MOST NE AREAS (INCLUDING PORTIONS
OF THE TIDEWATER AREA) INTO EARLY THU MORNING. LOWS WED NIGHT
RANGING FM THE MID 30S TO MID 40S. CHILLY W/NW WINDS AND DRIER AIR
EXPECTED ON THU...AS THE STRONG LO MOVES NE OFF THE NEW ENGLAND
CST. PARTLY TO MOSTLY SUNNY (EXCEPT MOSTLY CLOUDY ERN SHORE) WITH
HIGHS IN THE MID 40S NE TO LOWER 50S S/SW. FRI WILL BE MOSTLY CLEAR
WITH COLDER LOW TEMPS IN THE MID 20S TO MID 30S AND HIGHS INTO
THE UPPER 40S TO AROUND 50.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AMPLIFIED FLOW PATTERN CONTINUES DURING THE FIRST PART OF THE
EXTENDED PERIOD 12Z GFS AND ECMWF REMAIN SOMEWHAT APART WITH
REGARD TO SFC LOW AND ASSOCIATED FRONT MOVING THROUGH THE AREA IN
THE SAT/SUN TIME FRAME. LAST 2 RUNS OF THE GFS HAVE BEEN FURTHER
NORTH...SUGGESTING ONLY A BRIEF PERIOD OF WINTRY PRECIP ACROSS OUR
NWRN COUNTIES SAT MORNING. ECMWF IS A BIT FURTHER NORTH THAN
PREVIOUS RUN...BUT IS WARMER...AND DELAYS DEEPENING OF SFC CYCLONE
UNTIL IT PASSES EAST OF AREA. UPSTART OF THIS IS HAVE MAINTAINED
MUCH OF THE PREVIOUS EXTENDED FORECAST WITH REGARD TO PRECIP...
ALTHOUGH AM A BIT FASTER IN PRECIP EXITING...PER LATEST GUIDANCE.
STILL EXPECT A POTENTIAL MIX OF RAIN/SNOW ACROSS THE NWRN COUNTIES...
BUT HAVE KEPT ALL RAIN ALL AREAS FROM 18Z SAT ON. PRECIP ENDS ON
ALL MODELS BEFORE 06Z SUNDAY...AND HAVE KEPT SUNDAY/MONDAY DRY
ATTM. AS FOR TEMPS SAT...COULD BE A SIGNIFICANT GRADIENT FROM NW
TO SE...ESPECIALLY IF GFS IS CORRECT. IN SITU WEDGE ON BOTH MODELS
IMPLIES NWRN AREAS POSSIBLY NOT GETTING ABOVE 40 DEG. SE VA/NE NC
SHOULD REACH 50 OR HIGHER...WITH UPR 50S A GOOD BET SHOULD GFS
VERIFY.
TEMPS SUNDAY/MONDAY CLOSE TO NORMAL...WITH MAX TEMPS 40S TO LOW 50S
AND MIN TEMPS 20S TO LOW 30S. NEXT BOUNDARY CROSSES REGION IN THE
MONDAY NIGHT/TUESDAY TIME FRAME. RIGHT NOW...NOT A LOT OF PRECIP
EXPECTED WITH FRONT...ALTHO SCTD SHOWERS POSSIBLE.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
IFR AND OCCASIONAL LIFR CONDITIONS PREVAIL ALL TERMINALS AT 18Z.
IFR WILL DOMINATE THROUGH 21Z-22Z AT KRIC...WITH CONDITIONS
GRADUALLY IMPROVING FROM WEST TO EAST ACROSS THE REGION AS INTENSE DRY
SLOT MOVES THROUGH. THIS WILL ALLOW PRECIP TO SIGNIFICANTLY
DIMINISH OR END COMPLETELY. AND...AS WINDS GRADUALLY SHIFT TO THE
SW...DRIER AIR WILL MOVE IN AND CONDITIONS SHOULD IMPROVE TO MVFR
BY 00Z AT KRIC...02Z-03Z AT KPHF/KECG/KORF AND BEFORE 06Z AT KSBY.
STILL THE POSSIBILITY OF AN ISOLATED TSTM AT KORF/ECG...BUT
POTENTIAL APPEARS TO HAVE DIMINISHED SOME OVER THE LAST FEW HOURS.
HAVE MAINTAINED VCTS BOTH TERMINALS.
CONDITIONS WILL CONTINUE TO IMPROVE OVERNIGHT...WITH VFR
PREVAILING THURSDAY AND FRIDAY. HOWEVER...WINDS WILL REMAIN GUSTY
THURSDAY OUT OF THE W/NW...WITH A FEW GUSTS APPROACHING 30
KT...ESPECIALLY AT KSBY. WINDS WILL SUBSIDE ON FRIDAY...WITH NEXT
POTENTIAL FOR MVFR/IFR CONDITIONS ON SATURDAY WITH AN APPROACHING
COLD FRONT.
&&
.MARINE...
...AS OF 1 PM...GLW ISSUED FOR CHESAPEAKE BAY...AS OBSERVATIONS
AND HI RES MODELS SUGGEST A 4-6 HOUR PERIOD OF GALES IN
ASSOCIATION WITH LARGEST PRESSURE FALLS AHEAD OF SFC LOW. WINDS
SHOULD DROP BACK TO SCA LEVELS BEFORE 00Z...WITH GUSTS AROUND 30
KT STILL A GOOD BET ON THE BAY. REMAINDER OF FORECAST IN GOOD SHAPE.
.PREV DISCUSSION...
EXTENDED GALE WARNING FOR NORTHERN COASTAL ZONES THROUGH THURSDAY
AFTERNOON WITH EARLY MORNING UPDATE. PER PREV DISCUSSION
BELOW...THERE MAY BE A LULL IN GALE FORCE WINDS WEDS NIGHT/THURS
MORNING...BUT ANY LULL WILL BE SHORT LIVED. STRONG CAA WILL INCREASE
EARLY THURSDAY MORNING AS WINDS BECOME MORE W/NW ALLOWING FOR STRONG
MIXING OVER THE WATER AGAIN THROUGH THURSDAY AFTERNOON.
STRONG SFC LOW PRESSURE SYSTEM LOCATED OVER THE TN VALLEY WILL
CONTINUE TO LIFT TO THE NE THIS MORNING AND CROSS THE REGION THIS
AFTERNOON. THE LOW WILL THEN INTENSIFY NE OF THE REGION. THIS WILL
BRING AN EXTENDED PERIOD OF STRONG WINDS/GALES AND HIGH SEAS/WAVES
TO THE MARINE AREA. NE WINDS HAVE INCREASED OVER THE WATERS EARLY THIS
MORNING WITH WINDS OVER THE BAY ALREADY REACHING SCA CONDITIONS.
WAVES BUILDING TO 3 TO 4 FT IN THE BAY WITH SEAS BUILDING TO
NEAR 5 FT IN THE SOUTHERN COASTAL WATERS. THUS HAVE OPTED TO BEGIN
SCA HEADLINES WITH THIS UPDATE. WILL ALSO BEGIN SCA HEADLINES FOR
THE ERN VA RIVERS AND THE CURRITUCK SOUND AS SCA CONDITIONS ARE
OBSERVED. WILL MAINTAIN GALE WARNING TIMING FOR THE NORTHERN COASTAL
ZONES AS WINDS/SEAS WILL BE QUICK TO RISE LATER THIS MORNING. SEAS
EXPECTED TO BUILD TO 10 FT 20 NM OUT BY MID AFTERNOON. AS THE LOW
LIFTS OVER THE WATERS THIS EVENING INTO THE OVERNIGHT...STILL
ANTICIPATE LOW LEVEL INVERSION OVER THE WATER TO SUPPRESS 30-40 KT
WINDS A FEW HUNDRED FEET AGL. GRADIENT INCREASES BEHIND FRONT AS SFC
LOW INTENSIFIES AND CAA INCREASES. HAVE OPTED TO EXTEND ALL SCA
HEADLINES AN ADDITIONAL 12 HOURS THROUGH THURS AFTERNOON.
BASED ON THE AFOREMENTIONED INVERSION...THERE COULD BE A LULL IN
GALES THURSDAY MORNING (ALTHOUGH STRONG SCA CONDITIONS STILL
EXPECTED) BEFORE CAA KICKS IN RESULTING IN BETTER MIXING. WINDS WILL
BECOME MORE W/NW THURSDAY AFTERNOON WITH GALES LIKELY FOR THE NRN
COASTAL WATERS AGAIN THURSDAY.
A SIMILAR EVENT EXPECTED SATURDAY NIGHT INTO EARLY MONDAY AS NEXT
FRONT AND DEEPENING SFC LOW CROSS REGION.
&&
.TIDES/COASTAL FLOODING...
FORECAST TIDAL ANOMALIES CONTINUE TO RUN 1.5 TO 2 FT ABOVE NORMAL
AT OCEAN CITY...BISHOPS HEAD AND CAMBRIDGE TONIGHT INTO THURS
MORNING TIMEFRAME. STILL THE POSSIBILITY OF LOW END MINOR TIDAL
FLOODING ON THE LOWER MD ESATERN SHORE AREAS ADJACENT TO THE BAY
WITH THE HIGH TIDE TONIGHT. HOWEVER...CONFIDENCE STILL NOT
HIGH...SO NO ADVY ISSUED ATTM. WILL CONTINUE TO EVALUATE FOR LATE
AFTERNOON FORECAST ISSUANCE. IT APPEARS THAT OCEAN CITY WILL
REMAIN BELOW MINOR FLOOD LEVELS SO NO ADVY ANTICIPATED THERE.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ633-
635>638.
SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 PM EST
THURSDAY FOR ANZ630>632-634-656-658.
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ630>632-634-
656-658.
GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ650-652-654.
&&
$$
SYNOPSIS...BMD/MAM
NEAR TERM...BMD/LKB
SHORT TERM...BMD/LKB
LONG TERM...JAB
AVIATION...WRS
MARINE...JDM/SAM/WRS
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1205 PM EST WED DEC 26 2012
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL TRACK FROM THE TENNESSEE
VALLEY ACROSS THE MID ATLANTIC TODAY...WITH THE ASSOCIATED COLD
FRONT PUSHING OFF THE COAST BY EARLY THURSDAY MORNING. HIGH
PRESSURE RETURNS THURSDAY AFTERNOON THROUGH FRIDAY. ANOTHER LOW
PRESSURE SYSTEM WILL AFFECT THE REGION ON SATURDAY.
&&
.NEAR TERM /UNTIL 10 PM THIS EVENING/...
UPDATE...WARM FRONT IS CURRENTLY DRAPED OVER CAPE HATTERAS DOWN
INTO NW SC EARLY THIS AFTN AND IS SLOW TO LIFT NWD. OVERALL...
THE LOCATION OF THE WARM FRONT IS MORE IN-LINE WITH RUC13 MODEL
SOLUTIONS. BEST CONVECTION/LIGHTNING HAS BEEN OBSERVED RIGHT ALONG
THIS BOUNDARY AND IS EXPECTED TO MOVE UP INTO NE NC AND FAR SE VA
BY LATE AFTN/EARLY EVENING. PLACEMENT OF THE WARM FRONT WILL BE
CRUCIAL IN DETERMINING GREATEST THUNDERSTORM THREAT THROUGH THE
REMAINDER OF THIS AFTN/EARLY EVENING.
MODEL SOUNDINGS FOR KECG HINTED AT BRIEF LLVL DRYING DEVELOPING
DURING THIS AFTN BEFORE THE ATMOSPHERIC PROFILE BECOMES FULLY
SATURATED AGAIN. IF THIS DRYING IS REALIZED...THEN THIS WOULD
SUPPORT STRONG AND POTENTIALLY DAMAGING THUNDERSTORM WIND GUSTS IN
THE NE NC AND FAR SE VA VICINITIES. THIS PARTICULAR REGION ALSO
SITS WITHIN FAVORABLE VEERING WIND SHEAR PROFILES (20-25 KT SE SFC
WINDS VEERING TO SW 45-70 KT ALOFT)...WHICH ALSO SUPPORTS ISOLATED
TORNADO/WATERSPOUT POTENTIAL AS WELL AS . LATEST RADAR
RETURNS/OBSERVATIONS DO SHOW A SMALL AREA OF LITTLE TO NO PRECIP
AHEAD OF A MORE ORGANIZED CONVECTIVE LINE OF SHOWERS ASSOCIATED
WITH THE SFC COLD FRONT...THUS SUPPORTING THE AFOREMENTIONED
ASSESSMENT. WILL THEREFORE CONTINUE ENHANCED WORDING FOR STRONG TO
SEVERE THUNDERSTORMS IN FAR SE CWA COUNTIES INTO EARLY THIS
EVENING WHERE SPC CONTINUES ITS SLIGHT RISK AREA.
PREVIOUS DISCUSSION (702 AM EST)...LATEST WX ANALYSIS DEPICTS A
~995 MB SFC LOW CENTERED ACRS ERN TENNESSEE...AND A ~1032 MB SFC
HIGH PRESSURE NORTH OF THE CENTRAL GREAT LAKES. TEMPS ARE STILL
ABOVE FREEZING OVER ALL OF THE CWA...EVEN IN THE PIEDMONT...BUT
OBS HAVE REPORTED LIGHT SNOW AND/OR SLEET AT LKU/CHO AND NHK.
INITIAL BATCH OF STEADIER MODERATE PRECIP IS NOW LIFTING OFF TO
THE NE OF RICHMOND...WITH LIGHTER MORE SPOTTY PRECIP ALLOWING FOR
RAIN TO MIX BACK IN AT LKU/CHO. HAVE ADJUSTED FCST FOR CURRENT
CONDITIONS...BUT LITTLE CHANGE IN OVERALL THINKING FOR TODAY...AS
PRECIP RATES INCREASE THERE IS STILL THE POTENTIAL FOR MIXED
SNOW/SLEET OVER FAR NORTHERN TIER OF CWA THROUGH 15Z...BECOMING
CONFINED TO WRN LOUISA/FLUVANNA 15Z-17Z AND THEN SHOULD BE ALL
RAIN THEREAFTER. LITTLE TO NO ACCUMULATION (IF THERE IS ANY
ACCUMULATION IT SHOULD BE LIGHT AND LIMITED TO GRASSY SURFACES
OVER WRN LOUISA/FLUVANNA...NOT CLOSE TO ENOUGH FOR AN ADSY).
THE OTHER CONCERN TODAY IS POTENTIAL FOR SEVERE WX. SPC HAS MUCH
OF THE CWA OUTLINED IN SLIGHT RISK FOR SEVERE THIS AFTN/EARLY
EVENING. BASED ON WHAT OCCURRED YESTERDAY IN THE DEEP SOUTH
(LIGHTNING STRIKES OCCURRING WHERE LI`S HAVE BEEN +5 OR GREATER...
BUT WITH NEGATIVE SHOWALTER INDICES (ELEVATED INSTABILITY)...HAVE
EXTENDED CHC FOR TSTMS LATER THIS AFTN/EARLY EVENING A BIT FARTHER
NORTH TO INCLUDE MUCH OF CENTRAL VA/METRO RICHMOND. STRONG 0-6 KM
BULK SHEAR (60-80 KT) WILL BE CROSSING THE AREA AFTER 18Z...AND
THIS SHOULD BE ENOUGH TO GENERATE AT LEAST SOME EMBEDDED TSTMS
EVEN WITH NO SFC BASED CAPES. HAVE FOCUSED CHC TSTMS FROM 2 PM-6
PM WELL NORTH OF WHERE THE LOW LEVEL INSTABILITY IS FORECAST TO
OCCUR..FOLLOWING CLOSE TO RAP NEGATIVE SHOWALTER INDICES. WITH
THAT SAID...THINK THE CHC FOR SEVERE TSTMS WILL BE MUCH FARTHER
SOUTH...CONFINED TO AREAS WHERE DEW PTS GET INTO THE MID 50S OR
HIGHER AND TEMPS REACH 60 F OR HIGHER. LOOKING AT SPC STORM
REPORTS...THIS IS WHAT HAS HAPPENED THUS FAR. THIS TRANSLATES TO
BEST POTENTIAL FOR SEVERE WX OVER FAR SE/SRN VA AND NE NC. HAVE
MENTIONED THIS IN THE HWO AND HAVE ENHANCED WORDING IN THE GRIDDED
FCST FOR FAR SE VA/NE NC.
OVERALL...RAINFALL RATES ACROSS THE AREA WILL BECOME MODERATE TO
OCCASIONALLY HEAVY AHEAD OF/WITH THE COLD FRONTAL PASSAGE THIS
AFTN/EVENING. PRECIP TOTALS THROUGH TONIGHT/THU RANGE FROM 1.25
TO 1.75 INCHES (WHERE HIGHER AMTS WILL BE LOCATED ALONG THE
IMMEDIATE COAST). SOME AREAS COULD SEE LOCALLY HIGHER AMTS.
HIGHS AROUND 40 EXTREME NW TO THE LWR-MID 60S FAR SE VA AND
POSSIBLY INTO THE UPPER 60S IN NE NC.
&&
.SHORT TERM /10 PM THIS EVENING THROUGH FRIDAY/...
STRONG SFC LOW WILL LIFT NE OF THE AREA LATE TONIGHT INTO EARLY THU
MORNING...WITH THE TRAILING UPPER LOW MOVING ACROSS NRN VA/SE MD
AND DE. WILL LINGER POPS ACROSS MOST NE AREAS (INCLUDING PORTIONS
OF THE TIDEWATER AREA) INTO EARLY THU MORNING. LOWS WED NIGHT
RANGING FM THE MID 30S TO MID 40S. CHILLY W/NW WINDS AND DRIER AIR
EXPECTED ON THU...AS THE STRONG LO MOVES NE OFF THE NEW ENGLAND
CST. PARTLY TO MOSTLY SUNNY (EXCEPT MOSTLY CLOUDY ERN SHORE) WITH
HIGHS IN THE MID 40S NE TO LOWER 50S S/SW. FRI WILL BE MOSTLY CLEAR
WITH COLDER LOW TEMPS IN THE MID 20S TO MID 30S AND HIGHS INTO
THE UPPER 40S TO AROUND 50.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AMPLIFIED FLOW PATTERN CONTINUES DURING THE FIRST PART OF THE
EXTENDED PERIOD 12Z GFS AND ECMWF REMAIN SOMEWHAT APART WITH
REGARD TO SFC LOW AND ASSOCIATED FRONT MOVING THROUGH THE AREA IN
THE SAT/SUN TIME FRAME. LAST 2 RUNS OF THE GFS HAVE BEEN FURTHER
NORTH...SUGGESTING ONLY A BRIEF PERIOD OF WINTRY PRECIP ACROSS OUR
NWRN COUNTIES SAT MORNING. ECMWF IS A BIT FURTHER NORTH THAN
PREVIOUS RUN...BUT IS WARMER...AND DELAYS DEEPENING OF SFC CYCLONE
UNTIL IT PASSES EAST OF AREA. UPSTART OF THIS IS HAVE MAINTAINED
MUCH OF THE PREVIOUS EXTENDED FORECAST WITH REGARD TO PRECIP...
ALTHOUGH AM A BIT FASTER IN PRECIP EXITING...PER LATEST GUIDANCE.
STILL EXPECT A POTENTIAL MIX OF RAIN/SNOW ACROSS THE NWRN COUNTIES...
BUT HAVE KEPT ALL RAIN ALL AREAS FROM 18Z SAT ON. PRECIP ENDS ON
ALL MODELS BEFORE 06Z SUNDAY...AND HAVE KEPT SUNDAY/MONDAY DRY
ATTM. AS FOR TEMPS SAT...COULD BE A SIGNIFICANT GRADIENT FROM NW
TO SE...ESPECIALLY IF GFS IS CORRECT. IN SITU WEDGE ON BOTH MODELS
IMPLIES NWRN AREAS POSSIBLY NOT GETTING ABOVE 40 DEG. SE VA/NE NC
SHOULD REACH 50 OR HIGHER...WITH UPR 50S A GOOD BET SHOULD GFS
VERIFY.
TEMPS SUNDAY/MONDAY CLOSE TO NORMAL...WITH MAX TEMPS 40S TO LOW 50S
AND MIN TEMPS 20S TO LOW 30S. NEXT BOUNDARY CROSSES REGION IN THE
MONDAY NIGHT/TUESDAY TIME FRAME. RIGHT NOW...NOT A LOT OF PRECIP
EXPECTED WITH FRONT...ALTHO SCTD SHOWERS POSSIBLE.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
STRONG SFC LOW PRESSURE WILL CONTINUE TO LIFT OUT OF THE DEEP
SOUTH EARLY THIS MORNING AS HIGH PRESSURE REMAINS WEDGED OVER THE MID
ATLANTIC. CURRENTLY...BKN/OVC SKIES WITH DECKS GENERALLY 3 TO 6K
FT AGL WILL CONTINUE TO LOWER THROUGH 12Z UNDER NELY FLOW ALOFT.
THE EXCEPTION WILL BE IN SE VA/NE NC WHERE NELY FLOW WILL RESULT
IN LOCALIZED IFR CIGS THROUGH EARLY MORNING. OVERRUNNING WILL
SPREAD LIGHT/MODERATE RAIN NEWD THIS MORNING ACROSS THE REGION. IN
ADDITION...AN INCREASING LOW LEVEL JET MAY ENHANCE SOME WIND SHEER
THIS MORNING AT KRIC AND KSBY. WILL LEAVE OUT OF TAFS AS TIMING
WILL BE DIFFICULT AND CONFIDENCE IS LOW...SO WILL MONITOR AND
AMEND IF NEEDED. WINDS THROUGH 12Z WILL BE NELY AT 5 TO 15 KT WITH
GUSTS NEAR THE COAST UP TO 20 KT. EXPECT TO SEE THE CLOUDS
GRADUALLY LOWER WITH THE LOW LEVELS BECOMING SATURATED BETWEEN 12Z
AND 15Z. THIS WILL YIELD WIDESPREAD MVFR CONDITIONS DEVELOPING
AND AS THE ISENTROPIC LIFT INCREASES. CIGS AND VSBYS DROP TO IFR
LEVELS WITH THE INCREASING RAIN THREAT. THE CHALLENGE COMES DOWN
TO THE STRENGTH OF THE WEDGE...WHICH THE MODELS TRY TO ERODE
QUICKLY WITH THE SFC LOW FORMING OVER THE PIEDMONT AND LIFTING NE.
BUT EXPECT THAT THE WEDGE WILL BE STRONG WITH THE LOW FORMING JUST
EAST OF I-95. THIS WILL ALLOW THE WINDS TO SWITCH TO SE OR E FOR
ORF/ECG/SBY AND MAYBE AT PHF...BUT ANTICIPATE THAT RIC WILL REMAIN
CLOSER TO THE WEDGE SO DO NOT SHOW A GREAT DEAL OF IMPROVEMENT
LATE IN THE PERIOD...KEEPING THE IFR CONDITIONS THROUGH THE TAF.
THE OTHER SITES SHOULD BREAK INTO THE WARM SECTOR WHICH SHOULD
BRING THE CEILINGS AND VSBY BACK TO MVFR OR EVEN VFR CONDITIONS
AHEAD OF THE COLD FRONT...WHICH SHOULD CROSS BETWEEN 00Z AND 3Z.
WINDS WILL BE STRONGEST NEAR THE COAST WITH GUSTS UP TO 25-30 KT
THIS AFTERNOON.
THERE COULD STILL BE A CHANCE FOR A TSTM AS THE COLD FRONT PUSHES
THROUGH ON WEDNESDAY EVENING WITH BEST CHC AT ORF AND ECG.
CONDITIONS WILL IMPROVE BACK TO VFR BY THURSDAY AND CONTINUE VFR
ON FRIDAY. NEXT LOW APPROACHES FOR THE WEEKEND AND THIS COULD
AGAIN GENERATE MORE MVFR AND IFR CEILINGS.
&&
.MARINE...
EXTENDED GALE WARNING FOR NORTHERN COASTAL ZONES THROUGH THURSDAY
AFTERNOON WITH EARLY MORNING UPDATE. PER PREV DISCUSSION
BELOW...THERE MAY BE A LULL IN GALE FORCE WINDS WEDS NIGHT/THURS
MORNING...BUT ANY LULL WILL BE SHORT LIVED. STRONG CAA WILL INCREASE
EARLY THURSDAY MORNING AS WINDS BECOME MORE W/NW ALLOWING FOR STRONG
MIXING OVER THE WATER AGAIN THROUGH THURSDAY AFTERNOON.
.PREV DISCUSSION...
STRONG SFC LOW PRESSURE SYSTEM LOCATED OVER THE TN VALLEY WILL
CONTINUE TO LIFT TO THE NE THIS MORNING AND CROSS THE REGION THIS
AFTERNOON. THE LOW WILL THEN INTENSIFY NE OF THE REGION. THIS WILL
BRING AN EXTENDED PERIOD OF STRONG WINDS/GALES AND HIGH SEAS/WAVES
TO THE MARINE AREA. NE WINDS HAVE INCREASED OVER THE WATERS EARLY THIS
MORNING WITH WINDS OVER THE BAY ALREADY REACHING SCA CONDITIONS.
WAVES BUILDING TO 3 TO 4 FT IN THE BAY WITH SEAS BUILDING TO
NEAR 5 FT IN THE SOUTHERN COASTAL WATERS. THUS HAVE OPTED TO BEGIN
SCA HEADLINES WITH THIS UPDATE. WILL ALSO BEGIN SCA HEADLINES FOR
THE ERN VA RIVERS AND THE CURRITUCK SOUND AS SCA CONDITIONS ARE
OBSERVED. WILL MAINTAIN GALE WARNING TIMING FOR THE NORTHERN COASTAL
ZONES AS WINDS/SEAS WILL BE QUICK TO RISE LATER THIS MORNING. SEAS
EXPECTED TO BUILD TO 10 FT 20 NM OUT BY MID AFTERNOON. AS THE LOW
LIFTS OVER THE WATERS THIS EVENING INTO THE OVERNIGHT...STILL
ANTICIPATE LOW LEVEL INVERSION OVER THE WATER TO SUPPRESS 30-40 KT
WINDS A FEW HUNDRED FEET AGL. GRADIENT INCREASES BEHIND FRONT AS SFC
LOW INTENSIFIES AND CAA INCREASES. HAVE OPTED TO EXTEND ALL SCA
HEADLINES AN ADDITIONAL 12 HOURS THROUGH THURS AFTERNOON.
BASED ON THE AFOREMENTIONED INVERSION...THERE COULD BE A LULL IN
GALES THURSDAY MORNING (ALTHOUGH STRONG SCA CONDITIONS STILL
EXPECTED) BEFORE CAA KICKS IN RESULTING IN BETTER MIXING. WINDS WILL
BECOME MORE W/NW THURSDAY AFTERNOON WITH GALES LIKELY FOR THE NRN
COASTAL WATERS AGAIN THURSDAY.
A SIMILAR EVENT EXPECTED SATURDAY NIGHT INTO EARLY MONDAY AS NEXT
FRONT AND DEEPENING SFC LOW CROSS REGION.
&&
.TIDES/COASTAL FLOODING...
TIDAL ANOMALIES CONTINUE TO RUN 1.5 TO 2 FT ABOVE NORMAL AT OCEAN
CITY...BISHOPS HEAD AND CAMBRIDGE THIS AFTERNOON TO THURS MORNING
TIMEFRAME. THIS AFTERNOON/EVENINGS CYCLE IS THE LOWER OF THE 2
HIGH TIDES...SO TIDES WILL FALL BELOW ADVISORY CRITERIA TODAY.
TIDES ALSO EXPECTED TO FALL BELOW ADVISORY CRITERIA AGAIN TONIGHT.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ630>638-
656-658.
GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ650-652-654.
&&
$$
SYNOPSIS...BMD/MAM
NEAR TERM...BMD/LKB
SHORT TERM...BMD/LKB
LONG TERM...JAB
AVIATION...SAM
MARINE...SAM
TIDES/COASTAL FLOODING...AKQ
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1140 AM CST WED DEC 26 2012
.UPDATE...
ISSUED AT 809 AM CST WED DEC 26 2012
HAVE CANCELLED REMAINING ADVISORIES AND WARNINGS. BACK EDGE OF THE
ACCUMULATING SNOW IS CURRENTLY EXITING THE AREA.
ISSUED AT 553 AM CST WED DEC 26 2012
UPDATING FORECAST TO EXPIRE WARNINGS/ADVISORIES IN MISSOURI AND
CANCEL ST. CLAIR AND MONROE COUNTIES FROM THE WINTER WEATHER
ADVISORY IN ILLINOIS. SHARP BACK EDGE TO THE SNOW IS PROGRESSING
EASTWARD ANY ADDITIONAL ACCUMULATIONS IN METRO EAST WILL BE LITTLE
IF ANY.
BRITT
&&
.SHORT TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TODAY)
MAIN FOCUS WILL BE SNOWFALL AMOUNTS AND IMPACTS ASSOCIATED WITH
WINTER STORM. GOING FORECAST STILL LOOKS GOOD AND DO NOT PLAN ANY
CHANGE TO GOING HEADLINES WITH ONLY MINOR TWEAKS TO SNOWFALL
AMOUNTS. STILL EXPECT SOME BLOWING SNOW OVER THE DEEPEST SNOW COVER
FROM SOUTH OF THE METRO AREA INTO SOUTH CENTRAL ILLINOIS AS THE WIND
SPEEDS CONTINUE TO INCREASE.
LIGHT TO OCCASIONALLY MODERATE SNOW WITH ACCUMULATIONS AS HIGH AS
1.5 INCHES HAS BEEN REPORTED SO FAR OVER THE EASTERN OZARKS INTO FAR
SOUTHWEST ILLINOIS. JUST FLURRIES OR LIGHT SNOW HAS BEEN REPORTED
IN THE METRO AREA WITH JUST A DUSTING OVER SOUTH ST. LOUIS CITY.
IMPRESSIVE RADAR RETURNS ARE MOVING NORTHWARD INTO THE ILLINOIS
COUNTIES...THOUGH SURFACE OBS ARE NOT SHOWING MUCH MORE THAN
FLURRIES OR LIGHT SNOW. SATELLITE IS SHOWING THAT THE SYSTEM IS
QUICKLY MOVING TO THE NORTHEAST. THE RADAR MOSAIC DEPICTS THAT THE
THE BACK EDGE OF THE SNOW IS NOW BEGINNING TO MOVE EAST OVER SOUTH
CENTRAL MO/NORTH CENTRAL AR...SO THIS BACK EDGE WILL BEGIN TO
ACCELERATE EASTWARD THE NEXT FEW HOURS. BAND OF HIGHER RETURNS
THAT EXTENDS FROM THE METRO EAST SWWD TO NEAR FARMINGTON APPEARS
TO BE ASSOCIATED WITH A FRONTOGENETICAL BAND CENTERED AROUND
650MB. THE RAP SHOWS THIS BAND INTENSIFYING THROUGH 12Z BEFORE
WEAKENING AS IT MOVES EAST OF THE CWA BY MID-MORNING...SO THIS
WILL BE THE MAIN SNOW PRODUCER FOR US DURING THE EVENT. MOST
MODELS ARE SHOWING SUBSIDENCE SETTING IN OVER THE EASTERN CWA
AROUND NOON ENDING THE THREAT OF MEASURABLE PRECIPITATION. WINDS
WILL ALSO DECREASE BY LATE AFTERNOON AS LOW PRESSURE QUICKLY MOVES
TO THE EAST.
BRITT
&&
.LONG TERM...
ISSUED AT 300 AM CST WED DEC 26 2012
(TONIGHT THROUGH TUESDAY)
TONIGHT AND THURSDAY...CONFIDENCE HIGH
RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION. DRY WEATHER AND
SEASONAL TEMPERATURES EXPECTED. TRENDED FORECAST SLIGHTLY COLDER
OVER AREAS OF FRESH SNOW COVER.
THURSDAY NIGHT AND FRIDAY...CONFIDENCE LOW
NEXT STORM SYSTEM CURRENTLY CRASHING ONSHORE ALONG THE WEST COAST IS
ALREADY DIGGING FURTHER SOUTH THAN THE 00Z GFS AND ECWMF PORTRAYS.
GIVEN RECENT PERFORMANCE ISSUES WITH ALL MODEL GUIDANCE HAVE A HARD
TIME IMPROVING ON THE CURRENT FORECAST WHICH HAS A CHANCE OF SNOW
ACROSS THE CWA ON FRIDAY NIGHT WHEN THE LONGWAVE TROF AXIS SHOULD
SWING THRU. THIS WAVE SHOULD BE FULLY SAMPLED AT 12Z WHICH IN
THEORY SHOULD HELP THE MODELS CONVERGE ON A COMMON SOLUTION.
WEEKEND...CONFIDENCE MEDIUM
SHOULD BE DRY AND SEASONAL AS HIGH PRESSURE RIDGE MOVES ACROSS THE
REGION AND 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE.
NEXT WEEK...CONFIDENCE LOW
MODEL GUIDANCE AT ODDS WITH NEXT SHORTWAVE THAT SLAMS ONSHORE FRIDAY
NIGHT. THE GFS MAINTAINS THE PROGRESSIVE WEATHER PATTERN WITH
ANOTHER SOUTHERN LOW PRESSURE SYSTEM THAT COULD GIVE OUR SOUTHERN
CWA A SHOT AT ACCUMULATING SNOW. MEANWHILE...THE GEM AND ECWMF
CLOSE OFF THE DISTURBANCE INTO A DEEP LOW AND PUSH IT DUE SOUTH TO
THE BAJA OF MEXICO WITH DRY NORTHWEST FLOW FORECAST ACROSS THE
CENTER OF THE COUNTRY. FOR NOW HAVE MAINTAINED SLIGHT
CHANCE/NON-MENTIONABLE POPS FOR MONDAY THROUGH TUESDAY AND KEPT
TEMPERATURES NEAR NORMAL VALUES.
CVKING
&&
.AVIATION...
ISSUED AT 1125 AM CST WED DEC 26 2012
SURFACE LOW NOW OVER EASTERN KENTUCKY WILL CONTINUE MOVING
AWAY...ALLOWING SURFACE HIGH PRESSURE TO BUILD IN FROM THE WEST.
CIGS NEAR AOA 3K FT SHOULD PERSIST OVER EASTERN MO INTO IL THROUGH
AROUND 06Z...THEN BEGIN TO CLEAR. WHILE A LARGE AREA OF CLEAR
SKIES EXISTS OVER CENTRAL MO AS EVIDENT IN THE SATELLITE
LOOP...CLOUDS BUILDING SOUTHWARD AGAIN SHOULD BRING CIGS AOA 3K FT
BY EARLY AFTERNOON THERE. WINDS BECOME LIGHT AND VARIABE AREAWIDE
BY LATE EVENING...SO THERE MAY BE SOME PATCHY FOG.
SPECIFICS FOR KSTL...CIGS AOA 3K FT SOULD PERSIST UNTIL AT LEAST
06Z...THEN GRADUALLY CLEAR. GUSTY NW WINDS WILL ALSO DIMINISH BY
AROUND 06Z...THEN BECOME SOUTHEAST BY AROUND 20Z THURSDAY AS
SURFACE HIGH PRESSURE MOVES TO THE EAST.
BROWNING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1212 PM CST WED DEC 26 2012
.AVIATION...
18Z TAFS FOR KOFK...KOMA AND KLNK.
VFR CONDITIONS EXPECTED TO CONTINUE THROUGH 27/12Z WITH
CONDITIONS BECOMING MVFR TO IFR AFTER 12Z AS UPPER SYSTEM
SPREADS SNOW INTO THE AREA AS IT MOVES INTO THE NORTHERN
PLAINS.
&&
.PREV DISCUSSION... /ISSUED 305 AM CST WED DEC 26 2012/
DISCUSSION...
SNOW AMOUNTS THURSDAY/THURSDAY NIGHT ARE THE MAIN FORECAST FOCUS
AS WEST COAST SYSTEM PROVIDES A PROLONGED PERIOD OF WEAK TO
MODERATE LIFT ACROSS THE AREA. HOW FAR SOUTH WILL THESE MODEST
SNOW AMOUNTS POTENTIALLY EXTEND IS ALSO AN ISSUE. AFTER THIS
SYSTEM DEPARTS...REMAINDER OF FORECAST WILL BE DRY WITH MINOR
TEMPERATURE FLUCTUATIONS.
EARLY MORNING SATELLITE IMAGERY SHOWED FORECAST AREA IN BETWEEN
NRN PLAINS TROUGH/MS VALLEY CLOSED LOW AND APPROACHING BROAD WEST
COAST TROUGH. THUS AFTER A MAINLY EARLY DAY PERIOD OF MID
CLOUDINESS NRN ZONES ALONG WITH PSBL FLURRIES...PTLY/MOSTLY SUNNY
START TO DAY SHOULD BE FOLLOWED BY INCREASING CLOUDS LATER AS
WEST COAST TROUGH SPREADS SOME HIGH CLOUDS AND THEN THICKENING
WARM ADVECTION MID LEVEL CLOUDS TOWARD AND ACROSS THE FORECAST
AREA. BOOSTED SOME TEMPERATURES THIS AFTN...ESPECIALLY NWRN ZONES
WHERE WARM ADVECTION...LATE MORNING/EARLY AFTN SUN AND LESSER
SNOW COVER SUPPORT RAP SFC TEMP FORECAST OF NEAR OR ABOVE 20 F.
WEST COAST SYSTEM HAD DECENT 100+ M HGT FALLS AT H5 FM CNTRL CA
INTO WA LAST EVENING...AND AS IT MOVES ACROSS THE ROCKIES...00Z
NAM/GFS/ECMWF WERE SIMILAR IN CLOSING OFF H7 LOW AND PLACING INTO
CNTRL NEBR JUST WEST OF WCNTRL ZONES AT 00Z FRIDAY. LOW THEN
FORECAST TO SLOWLY LIFT ENE ACROSS NERN NEBR THU NGT ALTHOUGH
MODELS BEGIN DIVERGING ON AMOUNT OF ENERGY/LIFT LAGS BACK. BROAD
WARM ADVECTION...DEPICTED NICELY ON 285K ISENTROPIC SURFACES...SHOULD
BEGIN THICKENING CLOUDS OVER AREA LATE TONIGHT INTO MIDDAY
THURSDAY FOLLOWED BY INCREASING SNOW AREA. APPEARS A GENERAL
0.10-0.20 QPF TOTAL GENERATED BY SREF/NAM/GFS/ECMWF IS
ACCEPTABLE...ALTHOUGH IT WAS NOTED CANADIAN WAS ABOUT DOUBLE THAT
WHICH WOULD POSE MORE PROBLEMS SINCE WITH DEEP COLD AIRMASS IN
PLACE...SNOW TO LIQUID RATIOS COULD BE IN UPPER TEENS TO AROUND 20-1.
QUESTION BECOMES HOW FAR SOUTH WILL THE HIGHER QPF TOTALS EXTEND.
WOULD THINK THEY WOULD BE MOSTLY ALONG AND NORTH OF H7 TRACK WHICH
WOULD PLACE THEM MOSTLY NORTH OF HIGHWAY 30. HOWEVER...STEEP H7-H5
LAPSE RATES WERE NOTED SWRN ZONES THU AFTN AND ALONG KS/MO BORDERS
THU NGT WHICH COULD AID IN SOME SORT OF CONVECTIVE PCPN BANDS
SOUTHERN ZONES. THIS FORECAST WILL INCLUDE AMOUNTS AROUND 2
INCHES NEAR HIGHWAY 30 WITH 3-4 INCHES NORTH OF THERE AND AMOUNTS
LOWERING TO LESS THAN AN INCH SOUTH OF LINCOLN-SWRN IA. NO
HEADLINES YET AS WINDS EXPECTED TO BE MODEST AND THESE TOTALS
EXTEND AT LEAST OVER AN 18 HR PD. INCREASING CLOUDS SHOULD HOLD
TEMPS UP TONIGHT WITH LATE EVENING LOW PROBABLE MOST AREAS...BUT
CLOUDS AND SNOW COULD LIMIT WARMING NRN ZONES SOME DEGREE
THURSDAY.
WITH POTENTIALLY SLOWER DEPARTURE OF UPPER TROUGH...INCREASED SNOW
CHANCES NERN ZONES THU NGT AND EVEN FRIDAY MORNING FAR EAST.
TEMPERATURE PROFILE IN ANY LINGERING MOISTURE+PERSISTENT WEAK
LIFT PER NAM COULD KEEP LIGHT SNOW OR FLURRIES GOING WELL INTO
FRIDAY AND THUS FLURRIES WERE EXTENDED OVER NERN 1/3RD
EVEN FRI AFTN. DELAYED CLEARING SHOULD KEEP DIURNAL TEMPERATURE
RANGE SMALLER AND READINGS WERE ADJUSTED FOR SUCH.
AFTER THAT...AS MENTIONED ABOVE...FORECAST WAS KEPT DRY.
MODERATING TEMPERATURES EXPECTED SATURDAY INTO SUNDAY AS UPPER
RIDGING OCCURS BEFORE FLOW FLATTENS AS NRN STREAM TROUGH
APPROACHES. COULD CONCEIVABLY WARM NICELY SOME AREAS ON SUNDAY
AHEAD OF TROUGH...BUT HELD BACK BY SNOW COVER. NONETHELESS...DID
BOOST READINGS A LITTLE...THE MOST ON SUNDAY ACROSS THE SW. HIGHS
WERE KEPT IN CONSERVATIVE 20S MON/NEW YEARS DAY...BUT PER
ECMWF...ARCTIC AIR MAY REMAIN BOTTLED UP FARTHER NORTH THAN
THE FORECAST AREA.
CHERMOK
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
FOBERT
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
341 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG WINTER STORM WILL IMPACT THE AREA TONIGHT LEADING TO
HEAVY SNOW ACCUMULATIONS ACROSS THE ENTIRE FORECAST AREA. WRAP
AROUND MOISTURE WILL THEN RESULT IN CONTINUED SNOWS FOR MUCH OF
CENTRAL NEW YORK ON THURSDAY BEFORE HIGH PRESSURE SLOWLY BUILDS
INTO THE AREA TOWARDS THE CONCLUSION OF THE WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
CONDITIONS RAPIDLY DETERIORATING ACROSS THE AREA THIS AFTERNOON AS
LONG ADVERTISED WINTER STORM GETS UNDERWAY. REGIONAL WATER VAPOR
IMAGERY SHOWING MAIN MID-LEVEL CIRCULATION SLIDING ACROSS THE
EASTERN TN/KY BORDER THIS AFTERNOON...WITH NOTABLE DRY SLOT
BEGINNING TO WORK NORTH TOWARDS PIT AS SYSTEM CONTINUES THE
OCCLUSION PROCESS. LATEST RUC TROP PRESSURE FIELD SHOWS MAIN WAVE
NOW TAKING ON A NEGATIVE TILT WHICH SUGGEST UPPER FEATURE IS
REACHING MATURITY. MEANWHILE ALONG THE SURFACE...SECONDARY LOW
PRESSURE DEVELOPMENT NOW TAKING SHAPE ACROSS THE NORTH CAROLINA
PIEDMONT REGION...WITH SFC PRESSURE FIELDS REVEALING A NOTABLE
COLD AIR DAMMING SIGNATURE ALONG THE EASTERN SPIN OF THE
APPALACHIANS. IF NOTHING LESS...THE PRESENCE OF THIS SIGNATURE
WILL HELP ENSURE CONDITIONS ARE PRE-CONDITIONED FOR A ROUND OF
HEAVY SNOWFALL ACROSS THE FCST AREA TONIGHT AS WARM AIR ADVECTION
FORCING INCREASES IN ADVANCE OF THE SECONDARY LOW PRESSURE
SYSTEM/S MOVEMENT UP THE EAST COAST.
THE ABOVE SAID...LATEST RADAR TRENDS SHOWING SNOW MAKING STEADY
PROGRESS NORTHWARD THIS AFTERNOON WITH SNOW ALREADY BEING
REPORTED AT BOTH ELM AND AVP. QUICK INSPECTION OF RUC LAYERED
THETA-E LAPSE RATES SUGGEST A FAIR AMOUNT OF CONDITIONAL
INSTABILITY EXISTS ALOFT WHICH WILL LEAD TO SNOWFALL RATES ON THE
ORDER OF 2-3`/HR UNDER THE HEAVIEST ACTIVITY. DESPITE THE FACT THE
STORM IS ALREADY ONGOING ACROSS THE AREA...A FAIR AMOUNT OF MODEL
UNCERTAINTY STILL EXISTS WITH EXPECTED CONDITIONS OVERNIGHT AS THE
SECONDARY LOW PASSES TO OUR SOUTH AND EAST. WHAT DOES APPEAR FOR
CERTAIN IS THAT THE HEAVIEST SNOWFALL WILL OCCUR BETWEEN NOW AND
06Z AS THE MAIN AREA OF FRONTOGENESIS AND WARM AIR ADVECTION
FORCING LIFTS THROUGH THE FCST AREA. UNFORTUNATELY THIS WILL OCCUR
DURING THE AFTERNOON COMMUTE WHICH WILL UNDOUBTEDLY MAKE THINGS
DICEY FOR THOSE HEADING HOME THIS EVENING. MODELS CONTINUE TO
INSIST ON THE PREVIOUSLY MENTIONED DRY SLOT MOVING NORTH INTO OUR
AREA AFTER 06Z WHICH WILL LEAD TO A FAIR AMOUNT OF DRYING WITHIN
THE DENDRITIC SNOW GROWTH REGION. AS A RESULT...WE EXPECT TO SEE
THE HEAVY SNOW ZONE GRADUALLY ROTATE TO THE WEST WITH TIME AS A
POORLY DEFINED DEFORMATION AXIS ATTEMPTS TO FORM AFTER 06Z.
FURTHER TO THE EAST...PRONOUNCED DRY AIR ALOFT WILL LIKELY LEAD TO
A GRADUAL DECREASE IN SNOWFALL INTENSITY FOR THE SUSQUEHANNA
VALLEY REGION OF CENTRAL NY AND POINTS SOUTH TO INCLUDE THE TWIN
TIERS...POCONOS...AND LOWER WYOMING VALLEY. DESPITE THE PRESENCE
OF THE DRY SLOT...FORECAST MODELS CONTINUE TO PRODUCE LIGHT QPF
ACROSS THESE REGIONS WHICH LEADS US TO BELIEVE THAT FREEZING RAIN
AND PERHAPS SOME SLEET WILL BEGIN FOR THESE AREAS TOWARDS THE
EARLY MORNING HRS. IF THIS WERE TO OCCUR AS ADVERTISED...A FAIRLY
HEALTHY ICING EVENT MAY HAPPEN FOR THOSE LOCATIONS. FOR NOW WE
EXPECT THE HEAVIEST ICING TO OCCUR ACROSS THE WYOMING VALLEY AND
SOUTHERN POCONOS WHERE A QUARTER INCH OR MORE OF ICE WILL BE POSSIBLE.
ANOTHER INTRIGUING ASPECT OF THIS STORM IS THAT ALL MODELS TO
INCLUDE THE LOWER RESOLUTION ECMWF SHOW A SHADOWING EFFECT JUST
WEST OF THE CATSKILLS AFTER 06Z THIS EVENING. THIS SEEMS PLAUSIBLE
TO SOME DEGREE AS A STRONG EASTERLY LOW-LEVEL JET OF 70+KTS
IMPINGES ON THE MOUNTAIN RANGE. FOR NOREASTER TYPE EVENTS THIS
SEEMS VERY UNUSUAL HOWEVER WITH ALL SHORT TERM MODEL PROGS
CONTINUING TO INSIST THIS WILL OCCUR...HAVE ELECTED TO LOWER
SNOWFALL TOTALS ACROSS THE WESTERN CATSKILLS JUST A TAD.
SO TO SUM THINGS UP...THE HEAVIEST SNOWS ARE EXPECTED FROM THE
CHEMUNG RVR VLY NORTHEAST TROUGH THE FINGER LAKES AND WESTERN
MOHAWK VALLEY. ACROSS THESE LOCATIONS...ANYWHERE BETWEEN 10-14"
WILL BE POSSIBLE. FURTHER SOUTH AND EAST...8-10" ARE FORECAST
ACROSS THE TWIN TIERS AND WESTERN CATSKILLS...WITH 4-6" EXPECTED
FOR THE SOUTHERN CATSKILLS...POCONOS AND LOWER WYOMING VLY. NO
CHANGES MADE TO INHERITED HAZARDS WITH THE EXCEPTION OF BEEFING UP
THE WORDING FOR POTENTIAL ICE ACCUMULATIONS ACROSS THE SOUTH.
FOR THURSDAY...EXPECT SOME LINGERING WRAP AROUND MOISTURE TO LEAD
TO CONTINUED SNOW ACROSS PORTIONS OF UPSTATE NY. H85 TEMPS LOOK A
TAD TOO WARM TO RESULT IN ANY SIGNIFICANT LAKE ENHANCEMENT. WILL
CONTINUE TO CARRY LIKELY POPS ACROSS THE NORTH WITH SLGT CHC-CHC
TO THE SOUTH.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY...
STORM MOVES AWAY FROM THE AREA THURSDAY NIGHT. EXPECT SOME LIGHT
LAKE EFFECT SNOW SOUTH-SOUTHEAST OF LAKE ONTARIO WITH A 320 TO 325
DEGREE FLOW AND SOME LINGERING MOISTURE. HOWEVER WITH MARGINAL
TEMPERATURES AROUND -8 TO -10 DEGREES C AT 850 MB AND INVERSION HGTS
GENERALLY BELOW 5000 FEET EXPECT ONLY LIGHT ACCUMULATIONS... MAYBE
AROUND 2 INCHES ACROSS CENTRAL NY DOWN THROUGH AREAS SOUTHEAST OF
THE FINGER LAKES. DRYING MOVES IN WITH A WEAK RIDGE OF HIGH PRESSURE
ON FRIDAY PUTTING AN END TO ANY LINGERING LIGHT SNOW SHOWERS OR
FLURRIES DURING THE DAY.
NEXT SYSTEM APPROACHES THE AREA LATER FRIDAY NIGHT INTO SATURDAY.
MODEL CONSENSUS WITH THIS NEXT SYSTEM INDICATES A WEAK INVERTED
SURFACE TROUGH TRACKING ACROSS THE AREA WITH SOME LIGHT SNOW... BUT
SIGNIFICANT DEVELOPMENT OF THE SURFACE LOW DOES NOT OCCUR UNTIL THE
STORM IS WELL EAST OF THE MID-ATLANTIC COAST. THEREFORE HEAVY SNOW
DOES NOT APPEAR LIKELY AT THIS TIME.
.LONG TERM /SUNDAY THROUGH TUESDAY...
GFS AND ECMWF ARE IN REASONABLY GOOD AGREEMENT WITH THE OVERALL
PATTERN DURING THIS PERIOD INDICATING NORTHWEST FLOW WITH A SERIES
OF WEAKLY ORGANIZED CLIPPER SYSTEMS LIKELY ALONG WITH SOME LAKE EFFECT
SNOW. HOWEVER AT THIS POINT THERE IS NO INDICATION FOR ANY MAJOR
SYNOPTIC SCALE SYSTEMS THAT WOULD TAP GULF MOISTURE. TIMING OF THESE
INDIVIDUAL SYSTEMS WILL BE DIFFICULT BEYOND SUNDAY... BUT RIGHT NOW
THE BEST CHC FOR A WEAKLY ORGANIZED CLIPPER-LIKE SYSTEM COULD BE NEW
YEAR`S EVE INTO NEW YEAR`S DAY... WHICH WOULD BE FOLLOWED BY AN
ENHANCED PERIOD OF LAKE EFFECT SNOW. TEMPERATURES THROUGH THE PERIOD
WILL AVERAGE NEAR TO BELOW NORMAL... WITH HIGHS MAINLY IN THE MID
20S TO LOWER 30S AND LOWS IN THE TEENS. HAVE GONE WITH HPC GUIDANCE
THROUGH THE PERIOD INDICATING BEST CHANCES FOR SNOW WILL BE OVER
CENTRAL NY WITH SMALLER CHANCES TOWARD NORTHEAST PA.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
MODERATE TO HEAVY SNOW WILL OVERSPREAD THE TAF SITES FROM SOUTH TO
NORTH THROUGH 22Z. VSBYS WILL FALL TO AROUND HALF A MILE AND
OCCASIONALLY LOWER WITH CIGS BELOW 1000 FEET QUICKLY ONCE THE SNOW
STARTS. SNOW WILL BECOME LIGHTER THEN CHANGE TO LIGHT MIXED
PRECIPITATION AT AVP AFTER 01Z. FARTHER NORTH SNOW WILL BECOME
LIGHTER AFTER 03Z.
SNOW WILL BECOME SHOWERY ON THURSDAY WITH MVFR TO OCNL IFR
CONDITIONS PERSISTING THROUGH THE DAY IN CENTRAL NY. MVFR TO OCNL
VFR CONDITIONS CAN BE EXPECTED AT AVP WITH LIGHT MIXED
PRECIPITATION CHANGING TO LIGHT SNOW SHOWERS DURING THE AFTERNOON.
WINDS WILL BE E-NE AT 5 TO 15 KT TODAY INCREASING TO 10 TO 20 KT
TONIGHT THEN SHIFTING TO NW AT 10 TO 20 KTS ON THURSDAY.
OUTLOOK...
THUR NGT...MVFR/IFR IN SNOW SHOWERS ESPECIALLY OVER CENTRAL NY.
FRI...MAINLY VFR...MVFR/IFR POSSIBLE NORTHERN TERMINALS IN LAKE
EFFECT SNOW.
SAT...ANOTHER POSSIBLE WINTER SYSTEM AND THUS POSSIBLE IFR/MVFR.
SUN...MVFR/IFR POSSIBLE AT FOR CNY TERMINALS IN DEVELOPING LAKE
EFFECT SN.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR PAZ038>040-
043-044-047-048-072.
NY...WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR NYZ009-
015>018-022>025-036-037-044>046-055>057-062.
&&
$$
SYNOPSIS...CMG
NEAR TERM...CMG
SHORT TERM...MSE
LONG TERM...MSE
AVIATION...MSE
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1255 PM EST WED DEC 26 2012
.SYNOPSIS...
LOW PRESSURE SYSTEM WILL MOVE NORTH FROM TENNESSEE AND DEEPEN AS
IT TRACKS TOWARD THE MID ATLANTIC COAST THROUGH THIS EVENING. SEVERE
THUNDERSTORMS WILL BE POSSIBLE IN THE WARM MOIST AIRMASS THIS
AFTERNOON. A COLD FRONT WILL CROSS THE REGION THIS EVENING.
COOL AND DRY HIGH PRESSURE WILL BUILD IN THROUGH FRIDAY. ANOTHER
COLD FRONT WILL MOVE THROUGH LATE SATURDAY FOLLOWED BY HIGH
PRESSURE EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 12 PM WEDNESDAY...TORNADO WATCH CONTINUES WITH SEVERE
WEATHER STILL POSSIBLE EARLY THIS AFTERNOON. SLIGHT RISK FROM SPC
AS DYNAMIC FRONTAL SYSTEM MOVING UP FROM TENNESSEE TOWARD THE MID
ATLANTIC COAST THROUGH TODAY. SOUTHERLY LLJ UP TO 65 KTS COMBINING
WITH STRONG FORCING ASSOCIATED WITH A FAST MOVING COLD FRONT...AN
INCREASINGLY CLOSED AND NEGATIVELY TILTED UPPER TROUGH AND
FAVORABLE PLACEMENT RELATIVE TO AN UPPER JET EXIT REGION.
WARM FRONT MOVING NORTH HAS CLEARED LOCAL CWA WITH AREA RICH IN
DEWPOINTS IN THE LOWER 60S FOR THE MOST PART IN GUSTY SOUTHERLY
WINDS. SOME REPORTS OF GUSTS TO 35 MPH REPORTED INTO EARLY THIS
AFTERNOON. THIS WILL INCREASE SFC BASED CAPE BUT LATEST RUC NOT
VERY IMPRESSIVE WITH HIGHER CAPES REMAINING OFF SHORE. NAM STILL
SHOWING VALUES INCREASING UP TO 800 TO 1000 J/KG IN A SMALL AREA
LEADING UP FROM WINYAH BAY UP THROUGH HORRY AND ROBISON COUNTIES
EARLY THIS AFTERNOON. THIS AREA SHIFTS EAST NORTHEAST AND WEAKENS
AS COLD FRONT APPROACHES FROM THE WEST. LATEST OBS SHOWING DRY AIR
MAKING ITS WAY EAST INTO WESTERN PORTION OF CWA. DEWPOINTS
DROPPING WEST OF I95 THROUGH SOUTH CAROLINA INTO NORTH CAROLINA
WITH READINGS DOWN CLOSER TO 50 OR BELOW AS WINDS VEERING TO THE
SOUTHWEST.
WINDOW OF OPPORTUNITY FOR SEVERE WEATHER WILL BE SHRINKING THROUGH
THIS AFTERNOON AS WINDS SHIFT TO SOUTHWEST AND DRY AIR MAKES ITS
WAY IN. LOOKS LIKE SYSTEM HAS SPED UP IN TERMS OF BEST CHC OF
SEVERE WEATHER WITH GREATEST PROBABILITY IN WARM SECTOR AHEAD OF
APPROACHING COLD FRONT THROUGH MID AFTERNOON. MODELS IN FAIRLY
GOOD AGREEMENT WITH PEAK IN SVR WEATHER THREAT BETWEEN NOON AND 2
PM WITH DRY AIR MAKING ITS WAY IN AS WINDS SHIFT TO SOUTHWEST TO
WEST THROUGH LATE AFTERNOON. CONDITIONS RAPIDLY IMPROVE AFTER
THIS...ALTHOUGH IT WILL REMAIN BREEZY OVERNIGHT WITH TEMPERATURES
DROPPING INTO THE 30S MOST LOCATIONS AWAY FROM THE BEACHES.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...DEEP WEST TO NORTHWEST FLOW AND DRY AIR IN
THE WAKE OF EXITING STORM SYSTEM WILL KEEP THE REGION DRY FOR MUCH
OF THE PERIOD. COLD ADVECTION WILL BE LIMITED AS MID LEVEL TROUGH
LIFTING NORTHEAST LEAVES PROGRESSIVE FLOW IN PLACE THU/THU NIGHT. AS
ELONGATED SURFACE RIDGE AXIS SHIFTS EAST LOW LEVEL WINDS VEER FROM
NORTHWEST THU TO NORTHEAST ON FRI. AT THE SAME TIME SHORTWAVE
DROPPING INTO THE SOUTHWEST CONUS INDUCES WEAK MID LEVEL RIDGING
OVER THE SOUTHEAST. DEEP SOUTHWEST FLOW ALOFT STARTS ADVECTING
MOISTURE INTO THE REGION. FIRST HINT WILL BE CIRRUS DEVELOPMENT
LATER FRI FOLLOWED BY MID AND LOW LEVEL CLOUDS FRI NIGHT.
THE AFOREMENTIONED SOUTHWEST SHORTWAVE CONTRIBUTES TO DEVELOPMENT OF
GULF COAST LOW PRESSURE AT THE START OF THE WEEKEND. THIS LOW AND
ASSOCIATED MID LEVEL TROUGH MOVE INTO THE SOUTHEAST AS THE PERIOD
ENDS. STILL SOME UNCERTAINTY ON THE TRACK OF THE LOW AND WHETHER OR
NOT IT PASSES OVER OR OFF THE COAST BUT IT APPEARS THAT WILL BE AN
ISSUE FOR THE LONG TERM. ALTHOUGH GUIDANCE IS QUICK TO SHOW
SOUTHERLY FLOW DEVELOPING IT IS LIKELY THAT LOW LEVEL WEDGE HOLDS
STRONG INTO FIRST PART OF SAT...KEEPING ANY PRECIP LIGHT AND
STRATIFORM LATE FRI NIGHT. PLAN TO CARRY LOW CHANCE POP AS PERIOD
ENDS BUT WITH LITTLE TO NO QPF GIVEN THE AMOUNT OF LOW LEVEL DRY AIR
SHOWN IN FORECAST SOUNDINGS...SOMETHING WHICH FURTHER SUGGESTS THE
WEDGE WILL HOLD.
DESPITE LIMITED STRENGTH AND DURATION OF COLD ADVECTION TEMPERATURES
WILL RUN BELOW CLIMO THU/THU NIGHT. LOW LEVEL COLD POOL WILL KEEP
HIGHS IN THE UPPER 40S TO LOWER 50S WITH STRONG RADIATIONAL COOLING
THU NIGHT DROPPING TEMPS BELOW FREEZING IN MANY AREAS. NORTHEAST
FLOW FRI COMBINED WITH LOW SUN ANGLE LIMITS AIR MASS MODIFICATION
DURING THE DAY. HIGHS END UP WARMER THAN THU BUT STILL BELOW CLIMO.
CLOUD COVER AND WEAK BOUNDARY LAYER WINDS KEEP TEMPERATURES NEAR
CLIMO FRI NIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...MOST SIGNIFICANT WEATHER FEATURE WILL ALREADY
BE UNDERWAY AS THE PERIOD BEGINS. GULF COAST LOW TRACKING ACROSS THE
SOUTHEAST WILL BRING RAIN...SHOWERS AND POSSIBLE THUNDERSTORMS TO
THE SOUTHEAST SAT. UNCERTAINTY WITH RESPECT TO THE TRACK OF THE LOW
LIMITS THE SPECIFICITY OF THE FORECAST AT THIS POINT...BUT DO HAVE
FAIRLY HIGH CONFIDENCE IN PRECIP OCCURRING...HENCE LIKELY POP.
MEDIUM RANGE GUIDANCE IS SPLIT ON TAKING LOW OVER OR OFF THE COAST
SAT...THOUGH GFS ENSEMBLES HAVE BEEN TRENDING IN THE DIRECTION OF
PASSING THE MAIN SURFACE LOW JUST SOUTHEAST OF THE REGION...IN LINE
WITH 12Z ECMWF SOLUTION AND HPC SOLUTION. THIS SOLUTION WOULD
SUGGEST RAIN OPPOSED TO SHOWERS AND ISOLATED THUNDERSTORMS.
POSITIVE TO NEUTRAL TILT OF MID LEVEL TROUGH AND LIMITED
INTERACTION WITH NORTHERN STREAM QUICKLY MOVE THE SYSTEM ACROSS THE
SOUTHEAST AND INTO THE MID ATLANTIC REGION BY SAT NIGHT. AT THIS
POINT THE MID LEVEL TROUGH ATTAINS SOME NEGATIVE TILT AND THE STORM
STARTS TO DEEPEN. WHILE PRECIP WILL NOT BE AN ISSUE IN THE CAROLINAS
STRONG COLD ADVECTION ON THE BACKSIDE OF THE STORM PUSHES COLD AIR
OVER THE REGION FOR THE START OF NEXT WEEK. PARTIAL THICKNESS VALUES
SUGGEST HIGHS IN THE UPPER 40S TO LOWER 50S WITH LOWS IN THE UPPER
20S TO LOWER 30S SUN AND MON.
CONFIDENCE REMAINS LOW FOR THE END OF THE PERIOD WITH COLD FRONT
DROPPING IN FROM THE NORTH THEN STALLING ACROSS OR JUST SOUTH OF THE
AREA. MEANWHILE MEDIUM RANGE GUIDANCE IS SHOWING ANOTHER SOUTHWEST
SHORTWAVE AND WEAK GULF COAST CYCLOGENESIS LATE MON INTO TUE...WHICH
MAY OR MAY NOT QUICKLY MOVE ACROSS THE SOUTHEAST. GIVEN THAT THE
WAVE IS WELL OUTSIDE THE UPPER AIR SENSING NETWORK AND ALMOST A WEEK
AWAY WILL KEEP POP CAPPED AT SLIGHT CHANCE WITH TEMPERATURES NEAR
CLIMO.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 18Z...CONVECTION MARCHING TO THE COAST. FLO SHOULD BE OUT OF
THE WOODS EARLY ON...BECOMING VFR. LBT WILL FOLLOW SUIT AN HOUR OR
SO LATER. THE COAST WILL EXPERIENCE INTERMITTENT IFR CONDITIONS
THROUGH AROUND 21Z...WITH RAPIDLY IMPROVING CONDITIONS SHORTLY
AFTER. TONIGHT...VFR WITH GUSTY WEST SOUTHWEST WINDS BEHIND THE
FRONT. THINGS WILL SLOWLY SETTLE DOWN SOMEWHAT AFTER MIDNIGHT.
THURSDAY...VFR WITH A PREDOMINATELY WEST WIND...STRONGEST GUSTS
AROUND MID MORNING.
EXTENDED OUTLOOK...VFR WILL CONDITIONS WILL PERSISTING THROUGH
FRIDAY. MVFR/IFR CONDITIONS ARE POSSIBLE AGAIN SATURDAY AS ANOTHER
LOW PRESSURE SYSTEM AFFECTS THE AREA. VFR CONDITIONS EXPECTED SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12 PM WEDNESDAY...GALE WARNING CONTINUES WITH WINDS AND
SEAS UP ACROSS THE LOCAL WATERS WITH WINDS UP BETWEEN 25 AND 35
MOST WATERS AND SEAS UP TO 6 TO 9 FT.
EXTREMELY DANGEROUS BOATING CONDITIONS OVER ALL WATERS THROUGH
TONIGHT...WITH A GALE WARNING IN EFFECT INTO THE EARLY MORNING
HOURS OF THURSDAY. A POWERFUL STORM SYSTEM EMERGING FROM THE DEEP
SOUTH WILL BRING THE POSSIBILITY OF HEAVY RAIN...THUNDERSTORMS
AND WATER SPOUTS TO THE WATERS THROUGH THIS AFTERNOON.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM WEDNESDAY...WESTERLY FLOW AT THE START OF THE PERIOD MAY
REQUIRE SCA FOR THE FIRST FEW HOURS OF THU MORNING BEFORE SPEEDS
DROP UNDER 20 KT AS GRADIENT WEAKENS. SURFACE RIDGE AXIS SHIFTING
EAST LEADS TO FURTHER REDUCTION IN GRADIENT. THIS RESULTS IN WINDS
DECREASING AND VEERING FROM NORTHWEST LATE THU TO NORTHERLY THU
NIGHT. WINDS DROP UNDER 10 KT EARLY FRI AS RIDGE AXIS SHIFTS EAST
AND FLOW BECOMES NORTHEASTERLY. WEAK ONSHORE FLOW MAY DEVELOP LATE
IN THE PERIOD...BUT THIS WILL DEPEND ON THE LOCATION AND TRACK OF
SURFACE LOWS MOVING INTO THE SOUTHEAST AS THE PERIOD ENDS. STRONG
WESTERLY FLOW WILL RESULT IN A WIDE RANGE OF SEAS AT THE START OF
THE PERIOD...2 FT TO 7 FT NEAR 20 NM IN THE VICINITY OF FRYING PAN
SHOALS. CONTINUED REDUCTION IN WINDS COMBINED WITH GRADUAL VEERING
ALLOWS SEAS TO SUBSIDE TO 2 FT FOR FRI AND FRI NIGHT.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY...BRIEF PERIOD OF SOUTHERLY FLOW POSSIBLE
SAT...THOUGH EXACT TRACK OF MAIN SURFACE LOW REMAINS SOMEWHAT IN
QUESTION AND FLOW COULD END UP OFFSHORE THROUGH THE DURATION OF THE
PERIOD. CLOSE PROXIMITY OF WATERS TO SURFACE LOW WILL KEEP WINDS
UNDER 15 KT THROUGH SAT AFTERNOON. WEST TO NORTHWEST FLOW INCREASES
LATE SAT AS LOW EXITS AND STARTS TO DEEPEN OFF THE MID-ATLANTIC
COAST. STRENGTHENING LOW AND HIGH PRESSURE BUILDING IN FROM THE WEST
CONTRIBUTE TO AN INCREASE IN WINDS AND SEAS...POSSIBLY REQUIRING A
HEADLINE LATE SAT NIGHT THROUGH MIDDAY SUN. SURFACE HIGH CONTINUES
TO BUILD IN WITH GRADIENT STARTING TO RELAX IN THE AFTERNOON AND
NORTHWEST FLOW DECREASING TO 10 TO 15 LATE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...GALE WARNING UNTIL 3 AM EST THURSDAY FOR AMZ250-252-254-256.
&&
$$
NEAR TERM...RGZ
SHORT TERM...III
LONG TERM...III
AVIATION...DL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1245 PM EST WED DEC 26 2012
.SYNOPSIS...
LOW PRESSURE SYSTEM WILL MOVE NORTH FROM TENNESSEE AND DEEPEN AS
IT TRACKS TOWARD THE MID ATLANTIC COAST THROUGH THIS EVENING. SEVERE
THUNDERSTORMS WILL BE POSSIBLE IN THE WARM MOIST AIRMASS THIS
AFTERNOON. A COLD FRONT WILL CROSS THE REGION THIS EVENING.
COOL AND DRY HIGH PRESSURE WILL BUILD IN THROUGH FRIDAY. ANOTHER
COLD FRONT WILL MOVE THROUGH LATE SATURDAY FOLLOWED BY HIGH
PRESSURE EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 12 PM WEDNESDAY... SEVERE WEATHER STILL POSSIBLE EARLY THIS
AFTERNOON. SLIGHT RISK FROM SPC AS DYNAMIC FRONTAL SYSTEM MOVING
UP FROM TENNESSEE TOWARD THE MID ATLANTIC COAST THROUGH TODAY.
SOUTHERLY LLJ UP TO 65 KTS COMBINING WITH STRONG FORCING
ASSOCIATED WITH A FAST MOVING COLD FRONT...AN INCREASINGLY CLOSED
AND NEGATIVELY TILTED UPPER TROUGH AND FAVORABLE PLACEMENT
RELATIVE TO AN UPPER JET EXIT REGION.
WARM FRONT MOVING NORTH HAS CLEARED LOCAL CWA WITH AREA RICH IN
DEWPOINTS IN THE LOWER 60S FOR THE MOST PART IN GUSTY SOUTHERLY
WINDS. SOME REPORTS OF GUSTS TO 35 MPH REPORTED INTO EARLY THIS
AFTERNOON. THIS WILL INCREASE SFC BASED CAPE BUT LATEST RUC NOT
VERY IMPRESSIVE WITH HIGHER CAPES REMAINING OFF SHORE. NAM STILL
SHOWING VALUES INCREASING UP TO 800 TO 1000 J/KG IN A SMALL AREA
LEADING UP FROM WINYAH BAY UP THROUGH HORRY AND ROBISON COUNTIES
EARLY THIS AFTERNOON. THIS AREA SHIFTS EAST NORTHEAST AND WEAKENS
AS COLD FRONT APPROACHES FROM THE WEST. LATEST OBS SHOWING DRY AIR
MAKING ITS WAY EAST INTO WESTERN PORTION OF CWA. DEWPOINTS
DROPPING WEST OF I95 THROUGH SOUTH CAROLINA INTO NORTH CAROLINA
WITH READINGS DOWN CLOSER TO 50 OR BELOW AS WINDS VEERING TO THE
SOUTHWEST.
WINDOW OF OPPORTUNITY FOR SEVERE WEATHER WILL BE SHRINKING THROUGH
THIS AFTERNOON AS WINDS SHIFT TO SOUTHWEST AND DRY AIR MAKES ITS
WAY IN. LOOKS LIKE SYSTEM HAS SPED UP IN TERMS OF BEST CHC OF
SEVERE WEATHER WITH GREATEST PROBABILITY IN WARM SECTOR AHEAD OF
APPROACHING COLD FRONT THROUGH MID AFTERNOON. MODELS IN FAIRLY
GOOD AGREEMENT WITH PEAK IN SVR WEATHER THREAT BETWEEN NOON AND 2
PM WITH DRY AIR MAKING ITS WAY IN AS WINDS SHIFT TO SOUTHWEST TO
WEST THROUGH LATE AFTERNOON. CONDITIONS RAPIDLY IMPROVE AFTER
THIS...ALTHOUGH IT WILL REMAIN BREEZY OVERNIGHT WITH TEMPERATURES
DROPPING INTO THE 30S MOST LOCATIONS AWAY FROM THE BEACHES.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...DEEP WEST TO NORTHWEST FLOW AND DRY AIR IN
THE WAKE OF EXITING STORM SYSTEM WILL KEEP THE REGION DRY FOR MUCH
OF THE PERIOD. COLD ADVECTION WILL BE LIMITED AS MID LEVEL TROUGH
LIFTING NORTHEAST LEAVES PROGRESSIVE FLOW IN PLACE THU/THU NIGHT. AS
ELONGATED SURFACE RIDGE AXIS SHIFTS EAST LOW LEVEL WINDS VEER FROM
NORTHWEST THU TO NORTHEAST ON FRI. AT THE SAME TIME SHORTWAVE
DROPPING INTO THE SOUTHWEST CONUS INDUCES WEAK MID LEVEL RIDGING
OVER THE SOUTHEAST. DEEP SOUTHWEST FLOW ALOFT STARTS ADVECTING
MOISTURE INTO THE REGION. FIRST HINT WILL BE CIRRUS DEVELOPMENT
LATER FRI FOLLOWED BY MID AND LOW LEVEL CLOUDS FRI NIGHT.
THE AFOREMENTIONED SOUTHWEST SHORTWAVE CONTRIBUTES TO DEVELOPMENT OF
GULF COAST LOW PRESSURE AT THE START OF THE WEEKEND. THIS LOW AND
ASSOCIATED MID LEVEL TROUGH MOVE INTO THE SOUTHEAST AS THE PERIOD
ENDS. STILL SOME UNCERTAINTY ON THE TRACK OF THE LOW AND WHETHER OR
NOT IT PASSES OVER OR OFF THE COAST BUT IT APPEARS THAT WILL BE AN
ISSUE FOR THE LONG TERM. ALTHOUGH GUIDANCE IS QUICK TO SHOW
SOUTHERLY FLOW DEVELOPING IT IS LIKELY THAT LOW LEVEL WEDGE HOLDS
STRONG INTO FIRST PART OF SAT...KEEPING ANY PRECIP LIGHT AND
STRATIFORM LATE FRI NIGHT. PLAN TO CARRY LOW CHANCE POP AS PERIOD
ENDS BUT WITH LITTLE TO NO QPF GIVEN THE AMOUNT OF LOW LEVEL DRY AIR
SHOWN IN FORECAST SOUNDINGS...SOMETHING WHICH FURTHER SUGGESTS THE
WEDGE WILL HOLD.
DESPITE LIMITED STRENGTH AND DURATION OF COLD ADVECTION TEMPERATURES
WILL RUN BELOW CLIMO THU/THU NIGHT. LOW LEVEL COLD POOL WILL KEEP
HIGHS IN THE UPPER 40S TO LOWER 50S WITH STRONG RADIATIONAL COOLING
THU NIGHT DROPPING TEMPS BELOW FREEZING IN MANY AREAS. NORTHEAST
FLOW FRI COMBINED WITH LOW SUN ANGLE LIMITS AIR MASS MODIFICATION
DURING THE DAY. HIGHS END UP WARMER THAN THU BUT STILL BELOW CLIMO.
CLOUD COVER AND WEAK BOUNDARY LAYER WINDS KEEP TEMPERATURES NEAR
CLIMO FRI NIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...MOST SIGNIFICANT WEATHER FEATURE WILL ALREADY
BE UNDERWAY AS THE PERIOD BEGINS. GULF COAST LOW TRACKING ACROSS THE
SOUTHEAST WILL BRING RAIN...SHOWERS AND POSSIBLE THUNDERSTORMS TO
THE SOUTHEAST SAT. UNCERTAINTY WITH RESPECT TO THE TRACK OF THE LOW
LIMITS THE SPECIFICITY OF THE FORECAST AT THIS POINT...BUT DO HAVE
FAIRLY HIGH CONFIDENCE IN PRECIP OCCURRING...HENCE LIKELY POP.
MEDIUM RANGE GUIDANCE IS SPLIT ON TAKING LOW OVER OR OFF THE COAST
SAT...THOUGH GFS ENSEMBLES HAVE BEEN TRENDING IN THE DIRECTION OF
PASSING THE MAIN SURFACE LOW JUST SOUTHEAST OF THE REGION...IN LINE
WITH 12Z ECMWF SOLUTION AND HPC SOLUTION. THIS SOLUTION WOULD
SUGGEST RAIN OPPOSED TO SHOWERS AND ISOLATED THUNDERSTORMS.
POSITIVE TO NEUTRAL TILT OF MID LEVEL TROUGH AND LIMITED
INTERACTION WITH NORTHERN STREAM QUICKLY MOVE THE SYSTEM ACROSS THE
SOUTHEAST AND INTO THE MID ATLANTIC REGION BY SAT NIGHT. AT THIS
POINT THE MID LEVEL TROUGH ATTAINS SOME NEGATIVE TILT AND THE STORM
STARTS TO DEEPEN. WHILE PRECIP WILL NOT BE AN ISSUE IN THE CAROLINAS
STRONG COLD ADVECTION ON THE BACKSIDE OF THE STORM PUSHES COLD AIR
OVER THE REGION FOR THE START OF NEXT WEEK. PARTIAL THICKNESS VALUES
SUGGEST HIGHS IN THE UPPER 40S TO LOWER 50S WITH LOWS IN THE UPPER
20S TO LOWER 30S SUN AND MON.
CONFIDENCE REMAINS LOW FOR THE END OF THE PERIOD WITH COLD FRONT
DROPPING IN FROM THE NORTH THEN STALLING ACROSS OR JUST SOUTH OF THE
AREA. MEANWHILE MEDIUM RANGE GUIDANCE IS SHOWING ANOTHER SOUTHWEST
SHORTWAVE AND WEAK GULF COAST CYCLOGENESIS LATE MON INTO TUE...WHICH
MAY OR MAY NOT QUICKLY MOVE ACROSS THE SOUTHEAST. GIVEN THAT THE
WAVE IS WELL OUTSIDE THE UPPER AIR SENSING NETWORK AND ALMOST A WEEK
AWAY WILL KEEP POP CAPPED AT SLIGHT CHANCE WITH TEMPERATURES NEAR
CLIMO.
&&
.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
AS OF 18Z...CONVECTION MARCHING TO THE COAST. FLO SHOULD BE OUT OF
THE WOODS EARLY ON...BECOMING VFR. LBT WILL FOLLOW SUIT AN HOUR OR
SO LATER. THE COAST WILL EXPERIENCE INTERMITTENT IFR CONDITIONS
THROUGH AROUND 21Z...WITH RAPIDLY IMPROVING CONDITIONS SHORTLY
AFTER. TONIGHT...VFR WITH GUSTY WEST SOUTHWEST WINDS BEHIND THE
FRONT. THINGS WILL SLOWLY SETTLE DOWN SOMEWHAT AFTER MIDNIGHT.
THURSDAY...VFR WITH A PREDOMINATELY WEST WIND...STRONGEST GUSTS
AROUND MID MORNING.
EXTENDED OUTLOOK...VFR WILL CONDITIONS WILL PERSISTING THROUGH
FRIDAY. MVFR/IFR CONDITIONS ARE POSSIBLE AGAIN SATURDAY AS ANOTHER
LOW PRESSURE SYSTEM AFFECTS THE AREA. VFR CONDITIONS EXPECTED SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12 PM WEDNESDAY...GALE WARNING CONTINUES WITH WINDS AND
SEAS UP ACROSS THE LOCAL WATERS WITH WINDS UP BETWEEN 25 AND 35
MOST WATERS AND SEAS UP TO 6 TO 9 FT.
EXTREMELY DANGEROUS BOATING CONDITIONS OVER ALL WATERS THROUGH
TONIGHT...WITH A GALE WARNING IN EFFECT INTO THE EARLY MORNING
HOURS OF THURSDAY. A POWERFUL STORM SYSTEM EMERGING FROM THE DEEP
SOUTH WILL BRING THE POSSIBILITY OF HEAVY RAIN...THUNDERSTORMS
AND WATER SPOUTS TO THE WATERS THROUGH THIS AFTERNOON.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM WEDNESDAY...WESTERLY FLOW AT THE START OF THE PERIOD MAY
REQUIRE SCA FOR THE FIRST FEW HOURS OF THU MORNING BEFORE SPEEDS
DROP UNDER 20 KT AS GRADIENT WEAKENS. SURFACE RIDGE AXIS SHIFTING
EAST LEADS TO FURTHER REDUCTION IN GRADIENT. THIS RESULTS IN WINDS
DECREASING AND VEERING FROM NORTHWEST LATE THU TO NORTHERLY THU
NIGHT. WINDS DROP UNDER 10 KT EARLY FRI AS RIDGE AXIS SHIFTS EAST
AND FLOW BECOMES NORTHEASTERLY. WEAK ONSHORE FLOW MAY DEVELOP LATE
IN THE PERIOD...BUT THIS WILL DEPEND ON THE LOCATION AND TRACK OF
SURFACE LOWS MOVING INTO THE SOUTHEAST AS THE PERIOD ENDS. STRONG
WESTERLY FLOW WILL RESULT IN A WIDE RANGE OF SEAS AT THE START OF
THE PERIOD...2 FT TO 7 FT NEAR 20 NM IN THE VICINITY OF FRYING PAN
SHOALS. CONTINUED REDUCTION IN WINDS COMBINED WITH GRADUAL VEERING
ALLOWS SEAS TO SUBSIDE TO 2 FT FOR FRI AND FRI NIGHT.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY...BRIEF PERIOD OF SOUTHERLY FLOW POSSIBLE
SAT...THOUGH EXACT TRACK OF MAIN SURFACE LOW REMAINS SOMEWHAT IN
QUESTION AND FLOW COULD END UP OFFSHORE THROUGH THE DURATION OF THE
PERIOD. CLOSE PROXIMITY OF WATERS TO SURFACE LOW WILL KEEP WINDS
UNDER 15 KT THROUGH SAT AFTERNOON. WEST TO NORTHWEST FLOW INCREASES
LATE SAT AS LOW EXITS AND STARTS TO DEEPEN OFF THE MID-ATLANTIC
COAST. STRENGTHENING LOW AND HIGH PRESSURE BUILDING IN FROM THE WEST
CONTRIBUTE TO AN INCREASE IN WINDS AND SEAS...POSSIBLY REQUIRING A
HEADLINE LATE SAT NIGHT THROUGH MIDDAY SUN. SURFACE HIGH CONTINUES
TO BUILD IN WITH GRADIENT STARTING TO RELAX IN THE AFTERNOON AND
NORTHWEST FLOW DECREASING TO 10 TO 15 LATE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...GALE WARNING UNTIL 3 AM EST THURSDAY FOR AMZ250-252-254-256.
&&
$$
SYNOPSIS...
NEAR TERM...RGZ
SHORT TERM...III
LONG TERM...III
AVIATION...DL
MARINE...
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
413 PM EST WED DEC 26 2012
.SYNOPSIS...
POTENT WINTER STORM WILL RELAX ITS INFLUENCE ON THE OHIO VALLEY
THROUGH TONIGHT AND BE REPLACED BY WEAK HIGH PRESSURE ON THURSDAY.
NEXT WEAK TROUGH OF LOW PRESSURE WILL MOVE INTO THE AREA FRIDAY
NIGHT WITH THE NEXT CHANCE OF SNOW...ALBEIT LIGHT...AND FOCUSED ON
AREAS NEAR THE OHIO RIVER. TEMPERATURES OVER THE NEXT FEW DAYS
WILL REMAIN SEASONABLY COLD. IN THE LONGER TERM...NO MAJOR WEATHER
SYSTEMS ARE ON TAP FOR THE AREA.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
HAVE DOWNGRADED ALL WARNINGS TO ADVISORIES FOR MUCH OF THE AREA AS
IMPACTS OF WINTER STORM ARE BEGINNING TO RELAX. HAVE SEEN A
SLOW/STEADY DECREASE IN WINDS THROUGH THE AFTERNOON /THOUGH STILL
20-25KTS ACROSS WRN OH/ERN IND/...AND PRIMARY SNOW BAND THAT HAD
DEPOSITED 6-9 INCHES OF SNOW FROM SERN IND INTO WCNTL OH HAS
LARGELY BROKEN DOWN AND DECREASED IN INTENSITY. LARGER SYNOPTIC
BAND OF SNOW ACROSS MICHIGAN INTO NRN IND MAY WRAP E-NE INTO FAR
NRN FORECAST AREA THIS EVENING BUT LATEST RAP FORCING /FGEN/
DIAGNOSTICS INDICATE THIS WILL BEGIN TO BREAK DOWN AS WELL.
SO OVERALL...EXPECT BROKEN BANDS OF SNOW /MIXED WITH OR JUST PLAIN
RAIN ALONG AND SOUTH OF OHIO RIVER/ TO CONTINUE TO PROGRESS E-NE
ACROSS THE FORECAST AREA AS TRANSFER OF ENERGY TO DEEPER SFC LOW
ALONG THE ERN SEABOARD CONTINUES. STILL SEEING AN OCCASIONAL
REPORT OF FZDZ/FZRA/FZRAPL FROM TIME TO TIME...AND GIVEN CRITICAL
THERMAL STRUCTURE ON RAP FORECAST SOUNDINGS...SEE NO REASON WHY
THIS WON/T CONTINUE NEXT 1-2 HOURS...BEFORE COOLING ALOFT WILL
YIELD MORE OF A WIDESPREAD -SN SCENARIO FOR MOST OF THE ADVISORY
AREA. DON/T EXPECT MUCH MORE THAN AN ADDITIONAL INCH OF SNOW FOR
ANYONE...THOUGH AREAS NORTH/EAST OF COLUMBUS METRO STAND THE
BETTER CHANCES FOR PERHAPS A LITTLE MORE THAN AN INCH. ANY BLOWING
SNOW SHOULD DIMINISH EARLY TO MID EVENING...AND EXPECT TEMPS TO
ONLY FALL BACK INTO THE MID 20S...WHICH SHOULD AID IN ROAD
TREATMENTS/IMPROVEMENTS AS THE NIGHT WEARS ON.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
THURSDAY THROUGH FRIDAY ARE LARGELY A QUIET FORECAST...THOUGH
RESIDUAL/STUBBORN LOW LEVEL MOISTURE MAY CONTINUE TO YIELD
FLURRIES ESPECIALLY IN CNTL OHIO. TEMPERATURES THURSDAY NIGHT A
TRICKY POINT...GIVEN FRESH/DEEP SNOW COVER IN WRN/NRN PARTS OF
FORECAST AREA. APPRECIABLE CLEARING WILL SEND THOSE TEMPS INTO A
NOSEDIVE...AND COULD YIELD A SINGLE DIGIT OR TWO IF CLEARING IS
SUBSTANTIAL. NOT GOING THAT CLEAR ON SKY RIGHT NOW - SO HAVE KEPT
TEMPS NEAR/JUST BELOW STATISTICAL MOS GUIDANCE.
FRIDAY NIGHT A WEAK/POSITIVELY TILTED TROUGH /DISCUSSED BELOW IN
.LONG TERM SECTION/ WILL RACE NORTHEAST FROM THE SRN PLAINS...AND
INDUCE WEAK SFC LOW DEVELOPMENT IN THE SOUTHEAST. INVERTED TROUGH
AND ATTENDANT WEAK FORCING WILL SPREAD NORTHEAST ALONG WITH A
RATHER SUBSTANTIAL PLUME OF MOISTURE TO BRING RAIN/SNOW CHANCE
BACK INTO THE AREA...ESP NEAR/SOUTH OF THE OHIO RIVER. SIDED WITH
26.12Z ECMWF FORCING AND THERMAL CHARACTERISTICS FOR THIS FORECAST
THOUGH ADMITTEDLY 26.12Z GFS NOT TOO FAR OFF. SEE BELOW FOR MORE DETAILS.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A BROAD TROUGH OVER THE CENTRAL CONUS WILL SLIDE ACROSS THE OHIO
VALLEY ON SATURDAY. THE 26.12Z GFS/EUROPEAN/CANADIAN RUNS HAVE COME
INTO PRETTY GOOD AGREEMENT WITH REGARD TO THE TIMING OF THIS FEATURE
AND ITS ASSOCIATED MID LEVEL ENERGY AS IT PROGRESSES EASTWARD ACROSS
THE AREA. SOME LIGHT SNOW WILL BE POSSIBLE...ESPECIALLY ACROSS THE
SOUTHEASTERN CWA. COOLER AIR WILL SETTLE INTO THE REGION FOR THE
WEEKEND WITH HIGHS SATURDAY IN THE LOWER TO MIDDLE 30S...HIGHS
SUNDAY IN THE MID 20S TO LOWER 30S...AND LOWS BOTH NIGHTS IN THE
TEENS TO LOWER 20S.
CLOUDS WILL BEGIN TO DECREASE A BIT ON SUNDAY AS HIGH PRESSURE OVER
THE LOWER MS VALLEY MOVES NORTHEAST INTO THE REGION. THIS SYSTEM
WILL PROVIDE QUIET WEATHER THROUGH MONDAY MORNING. THE GFS AND ECMWF
THEN BEGIN TO DIVERGE SIGNIFICANTLY FOR THE REMAINDER OF THE
EXTENDED PERIOD...AND GEFS ENSEMBLE CLUSTERS SHOW CONSIDERABLE
SPREAD. A COLD FRONT IS PROGGED TO PUSH THROUGH THE AREA LATE MONDAY
NIGHT INTO TUESDAY...BRINGING THE NEXT CHANCE FOR SOME PRECIP.
FORECAST SOUNDINGS INDICATE THE ONSLAUGHT OF PRECIPITATION MONDAY
EVENING MAY BEGIN AS RAIN...SNOW...OR A MIX SOUTH OF THE OHIO RIVER
BEFORE COLDER TEMPERATURES CHANGE IT TO LIGHT SNOW. ELSEWHERE...
EXPECT JUST CHANCE/SLIGHT CHANCE FOR LIGHT SNOW AT TIMES THROUGH
WEDNESDAY.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
CENTER OF LOW IS CURRENTLY SPINNING EASTWARD ACROSS SOUTHERN
KENTUCKY. ACROSS OUR AREA AIR ALOFT HAS COOLED SUFFICIENTLY TO
ALLOW PRECIPITATION TO FALL PRIMARILY AS ALL SNOW NOW. THE ONLY
EXCEPTION APPEARS TO BE LOW LYING AREAS INCLUDING KLUK. THIS
LOCATION WILL ALSO SEE A CHANGEOVER TO SNOW BY 20Z. PRECIPITATION
WILL BEGIN TO TAPER OFF IN INTENSITY LATER THIS AFTERNOON AND BECOME
MORE SHOWERY IN NATURE...ENDING BY AROUND MIDNIGHT. CIGS HAVE
FALLEN TO IFR FOR THE MOST PART AND ARE EXPECTED TO REMAIN THAT
WAY THROUGHOUT THE NIGHT. AFTER SUNRISE THURSDAY...CIGS WILL
STRUGGLE TO RISE ABOVE IFR...ESPECIALLY NORTH TOWARD INTERSTATE
70. HOWEVER THERE MAY BE A WINDOW DURING THE LATE MORNING AND
AFTERNOON WHEN MVFR CIGS DO OCCUR. CIGS ARE EXPECTED TO THEN
LOWER BACK TO IFR BY THURSDAY EVENING.
OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES POSSIBLE SATURDAY
INTO SATURDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ026-
034-035-042>046-051>056-060>065-070>074-077>080.
KY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
KYZ089>099.
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ050-
058-059-066-073>075-080.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU
SHORT TERM...BINAU
LONG TERM...KURZ
AVIATION...LATTO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
441 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TONIGHT. STRONG
GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF
PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF
WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS
NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID- ATLANTIC
COAST.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS
LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT
SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES
TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH
SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES
BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA
INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS
TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING
RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL
AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON
BLENDED QPF AND PTYPE.
WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL
CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT
IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS
EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN
NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A
PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER
THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN
CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION.
THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH
SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS
AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS
REMAINED SNOW AT THE SURFACE.
STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE
SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED
PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND
NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE
COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE
COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES.
RAP HAS SHOWN FREEZING RAIN AT TIMES.
IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND
LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD
GET IN THE LOWER 40S IN EASTERN AREAS.
WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE
THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW
POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM.
MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST
MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO
THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY
ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT
SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY.
MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS.
MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS
SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA.
LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL
DIMINISH THURSDAY EVENING.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE MAIN STORY FOR THE LONG TERM IS COLD...NOT TERRIBLE/ANOMALOUS
COLD...BUT SEASONABLY COLD. THE PERIOD WILL START WITH THE EXIT OF
THE FIRST REAL STORM OF THE YEAR. GUSTY WEST WINDS SHOULD DECREASE
FROM ADVY LEVELS OVER THE SOUTH QUICKLY THURS EVENING/NIGHT. BUT
THE WESTERLY FLOW WILL KEEP UPSLOPE SNOW SHOWERS GOING UNTIL THE
SFC RIDGE GETS INTO WRN PA. THUS...WILL KEEP SCT/NMRS SHSN THURS
NIGHT AND VERY EARLY FRI AM OVER THE WESTERN MTNS. AFTER A BREAK
UNDER THE WEAK RIDGE...THE FAST FLOW BUCKLES A LITTLE AND DRAWS A
SYSTEM THROUGH ON SAT FROM THE SW. PROGRESSIVE PATTERN WILL KEEP
IT MOVING...BUT THERE IS A SMALL CHC THAT IT COULD PHASE WITH A
CLIPPER-TYPE SHORT WAVE MOVING ACROSS THE UPPER GREAT LAKES ABOUT
THAT SAME TIME. NONE OF THE MODELS REALLY FULLY PHASE THESE
SYSTEMS. WHILE THE OUTLIER NAM ZIPS THE SRN SYSTEM BY TO OUR SOUTH
AND MAKE LIGHT SNOW ONLY OVER THE LOWER SUSQ...THE GFS/EC/SREF
MEANS DO SPREAD PRECIP OVER ALL OF OUR AREA. THIS MEANS THAT IT
SHOULD BE A QUICK HITTER AND A 1-2 INCH SNOW FALL IS LIKELY AT
THIS POINT IN THE GAME.
BRIEF UPPER RIDGE MOVES IN FOR MONDAY...BUT THE FAST FLOW KEEPS
IT MOVING. THE MIDDLE OF THE WEEK WILL BE LESS CERTAIN WITH GFS
AND ECMWF DIFFERING ON THE UPPER HEIGHT PATTERN OVER THE WHOLE
CONUS. THE GFS ALSO OUT OF LINE WITH THE GEFS MEAN...WHICH ALONG
WITH THE ECMWF PORTRAY A MEAN TROUGH JUST EAST OF OUR LONGITUDE.
THIS SHOULD CREATE A NWRLY FLOW AND GENERALLY COLD AND SNOW
SHOWERY TIME FOR THE REST OF THE EXTENDED. A FEW CLIPPERS ARE
PROGGED TO RUN THROUGH THE GREAT LAKES FROM UPPER ONTARIO DURING
THE MID WEEK. SO WE KEPT POPS HIGH CHC IN THE NW AND LOWER/SLIGHT
CHCS IN THE SE. THE COLD AIR WILL KEEP IT ALL SNOW. NO MORE BIG
STORMS ON THE HORIZON OF DAY 7.
&&
.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
WIDESPREAD IFR/LIFR WILL CONTINUE INTO THE EVENING WITH LOCALLY
HEAVY SNOW IN CENTRAL AND NORTHERN AREAS...TRANSITIONING TO
RAIN/SLEET/FREEZING RAIN OVER SERN AREAS.
SOUTHEASTERN PA HAS GONE MAINLY TO FREEZING RAIN...A DEICING
ISSUE. MOST OF SOUTHEASTERN PA SHOULD GO TO ALL RAIN THIS EVENING.
KMDT AND KLNS SHOULD BE MAINLY RAIN THIS EVENING AND OVERNIGHT.
MIXED PRECIPITATION IS AN ISSUE FOR KJST-KAOO-KUNV-KIPT AND KSEG
LATER TONIGHT. FARTHER EAST MORE POTENTIAL FOR FREEZING RAIN AND
SLEET. CURRENT CONDITIONS AND FORECASTS BEFORE TAKE-OFF.
POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST
CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING.
ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER
LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS
IN THE 1-4KFT LEVELS THROUGH AT LEAST 0600 UTC.
SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST
OVERNIGHT INTO THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR
AT TIMES BEFORE 12Z THURSDAY. WINDS WILL BE AN ISSUE BEHIND THE
FRONT OVER MOST OF SOUTHERN PA THURSDAY. STRONG GUSTY NW WINDS ARE FORECAST.
IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND
BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST
MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH
MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS.
IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. MORE
SNOW AND MVFR IFR POSSIBLE SATURDAY.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS THROUGH MIDNIGHT WITH LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING BEFORE 12Z. SHSN CONTINUE
IN N AND W MTNS. LOW CIGS LIKELY IN N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING
AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE
MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD
LEAD TO MINOR FLOODING IN THE SOUTHEAST.
AT THIS TIME WE ARE OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING
SHOULD IT GET WARMER AND MORE RAIN THAN OTHER PRECIP WOULD BE
OBSERVED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006-
010>012-017>019-024>028-033>035-037-041-042-045-046-049>053-
058.
WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026-
033>036-064-065.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...GRUMM/ROSS
SHORT TERM...GRUMM/ROSS
LONG TERM...DANGELO
AVIATION...GRUMM/ROSS/LA CORTE
HYDROLOGY...LA CORTE
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
432 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TONIGHT. STRONG
GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL BRING A BRIEF
PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY. ANOTHER ROUND OF
WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW PRESSURE TRACKS
NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN MID- ATLANTIC
COAST.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS
LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT
SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES
TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH
SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES
BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA
INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS
TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING
RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL
AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON
BLENDED QPF AND PTYPE.
WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL
CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT
IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS
EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN
NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A
PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER
THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN
CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION.
THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH
SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS
AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS
REMAINED SNOW AT THE SURFACE.
STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE
SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED
PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND
NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE
COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE
COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES.
RAP HAS SHOWN FREEZING RAIN AT TIMES.
IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND
LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD
GET IN THE LOWER 40S IN EASTERN AREAS.
WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE
THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW
POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM.
MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST
MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO
THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY
ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT
SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY.
MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS.
MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS
SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA.
LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL
DIMINISH THURSDAY EVENING.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE MAIN STORY FOR THE LONG TERM IS COLD...NOT TERRIBLE/ANOMALOUS
COLD...BUT SEASONABLY COLD. THE PERIOD WILL START WITH THE EXIT OF
THE FIRST REAL STORM OF THE YEAR. GUSTY WEST WINDS SHOULD DECREASE
FROM ADVY LEVELS OVER THE SOUTH QUICKLY THURS EVENING/NIGHT. BUT
THE WESTERLY FLOW WILL KEEP UPSLOPE SNOW SHOWERS GOING UNTIL THE
SFC RIDGE GETS INTO WRN PA. THUS...WILL KEEP SCT/NMRS SHSN THURS
NIGHT AND VERY EARLY FRI AM OVER THE WESTERN MTNS. AFTER A BREAK
UNDER THE WEAK RIDGE...THE FAST FLOW BUCKLES A LITTLE AND DRAWS A
SYSTEM THROUGH ON SAT FROM THE SW. PROGRESSIVE PATTERN WILL KEEP
IT MOVING...BUT THERE IS A SMALL CHC THAT IT COULD PHASE WITH A
CLIPPER-TYPE SHORT WAVE MOVING ACROSS THE UPPER GREAT LAKES ABOUT
THAT SAME TIME. NONE OF THE MODELS REALLY FULLY PHASE THESE
SYSTEMS. WHILE THE OUTLIER NAM ZIPS THE SRN SYSTEM BY TO OUR SOUTH
AND MAKE LIGHT SNOW ONLY OVER THE LOWER SUSQ...THE GFS/EC/SREF
MEANS DO SPREAD PRECIP OVER ALL OF OUR AREA. THIS MEANS THAT IT
SHOULD BE A QUICK HITTER AND A 1-2 INCH SNOW FALL IS LIKELY AT
THIS POINT IN THE GAME.
BRIEF UPPER RIDGE MOVES IN FOR MONDAY...BUT THE FAST FLOW KEEPS
IT MOVING. THE MIDDLE OF THE WEEK WILL BE LESS CERTAIN WITH GFS
AND ECMWF DIFFERING ON THE UPPER HEIGHT PATTERN OVER THE WHOLE
CONUS. THE GFS ALSO OUT OF LINE WITH THE GEFS MEAN...WHICH ALONG
WITH THE ECMWF PORTRAY A MEAN TROUGH JUST EAST OF OUR LONGITUDE.
THIS SHOULD CREATE A NWRLY FLOW AND GENERALLY COLD AND SNOW
SHOWERY TIME FOR THE REST OF THE EXTENDED. A FEW CLIPPERS ARE
PROGGED TO RUN THROUGH THE GREAT LAKES FROM UPPER ONTARIO DURING
THE MID WEEK. SO WE KEPT POPS HIGH CHC IN THE NW AND LOWER/SLIGHT
CHCS IN THE SE. THE COLD AIR WILL KEEP IT ALL SNOW. NO MORE BIG
STORMS ON THE HORIZON OF DAY 7.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
SNOW IN NORTHERN AND CENTRAL AREAS WILL CONTINUE TO PRODUCE IFR TO
LIFR CONDITIONS INTO THIS EVENING. SOME MORE INTENSE SNOW BANDS
ARE POSSIBLE.
SOUTHEASTERN PA HAS GONE MAINLY TO FREEZING RAIN...A DEICING
ISSUE. MOST OF SOUTHEASTERN PA SHOULD GO TO ALL RAIN THIS EVENING.
KMDT AND KLNS SHOULD BE MAINLY RAIN THIS EVENING AND OVERNIGHT.
MIXED PRECIPITATION IS AN ISSUE FOR KJST-KAOO-KUNV-KIPT AND KSEG
LATER TONIGHT. FARTHER EAST MORE POTENTIAL FOR FREEZING RAIN AND
SLEET. CURRENT CONDITIONS AND FORECASTS BEFORE TAKE-OFF.
POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST
CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING.
ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER
LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS
IN THE 1-4KFT LEVELS THROUGH AT LEAST 0600 UTC.
SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST
OVERNIGHT INTO THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR
AT TIMES BEFORE 12Z THURSDAY. WINDS WILL BE AN ISSUE BEHIND THE
FRONT OVER MOST OF SOUTHERN PA THURSDAY. STRONG GUSTY NW WINDS ARE FORECAST.
IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND
BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST
MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH
MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS.
IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. MORE
SNOW AND MVFR IFR POSSIBLE SATURDAY.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS THROUGH MIDNIGHT WITH LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING BEFORE 12Z. SHSN CONTINUE
IN N AND W MTNS. LOW CIGS LIKELY IN N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING
AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE
MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD
LEAD TO MINOR FLOODING IN THE SOUTHEAST.
AT THIS TIME WE ARE OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING
SHOULD IT GET WARMER AND MORE RAIN THAN OTHER PRECIP WOULD BE
OBSERVED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006-
010>012-017>019-024>028-033>035-037-041-042-045-046-049>053-
058.
WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026-
033>036-064-065.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...GRUMM/ROSS
SHORT TERM...GRUMM/ROSS
LONG TERM...DANGELO
AVIATION...GRUMM/ROSS
HYDROLOGY...GRUMM/ROSS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
343 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA THIS AFTERNOON
AND TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF
THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID- ATLANTIC COAST.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS
LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT
SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES
TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH
SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES
BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA
INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS
TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING
RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL
AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON
BLENDED QPF AND PTYPE.
WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL
CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT
IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS
EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN
NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A
PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER
THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN
CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION.
THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH
SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS
AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS
REMAINED SNOW AT THE SURFACE.
STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE
SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED
PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND
NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE
COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE
COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES.
RAP HAS SHOWN FREEZING RAIN AT TIMES.
IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND
LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD
GET IN THE LOWER 40S IN EASTERN AREAS.
WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE
THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW
POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM.
MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST
MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO
THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY
ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT
SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY.
MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS.
MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS
SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA.
LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL
DIMINISH THURSDAY EVENING.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF
HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI
NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO
DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER
MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN
MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST.
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
SNOW IN NORTHERN AND CENTRAL AREAS WILL CONTINUE TO PRODUCE IFR TO
LIFR CONDITIONS INTO THIS EVENING. SOME MORE INTENSE SNOW BANDS
ARE POSSIBLE.
SOUTHEASTERN PA HAS GONE MAINLY TO FREEZING RAIN...A DEICING
ISSUE. MOST OF SOUTHEASTERN PA SHOULD GO TO ALL RAIN THIS EVENING.
KMDT AND KLNS SHOULD BE MAINLY RAIN THIS EVENING AND OVERNIGHT.
MIXED PRECIPITATION IS AN ISSUE FOR KJST-KAOO-KUNV-KIPT AND KSEG
LATER TONIGHT. FARTHER EAST MORE POTENTIAL FOR FREEZING RAIN AND
SLEET. CURRENT CONDITIONS AND FORECASTS BEFORE TAKE-OFF.
POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST
CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING.
ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER
LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS
IN THE 1-4KFT LEVELS THROUGH AT LEAST 0600 UTC.
SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST
OVERNIGHT INTO THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO MVFR
AT TIMES BEFORE 12Z THURSDAY. WINDS WILL BE AN ISSUE BEHIND THE
FRONT OVER MOST OF SOUTHERN PA THURSDAY. STRONG GUSTY NW WINDS ARE FORECAST.
IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND
BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST
MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH
MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS.
IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY. MORE
SNOW AND MVFR IFR POSSIBLE SATURDAY.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS THROUGH MIDNIGHT WITH LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING BEFORE 12Z. SHSN CONTINUE
IN N AND W MTNS. LOW CIGS LIKELY IN N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING
AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE
MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD
LEAD TO MINOR FLOODING IN THE SOUTHEAST.
AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD
IT GET WARMER AND MORE RAIN IS OBSERVED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006-
010>012-017>019-024>028-033>035-037-041-042-045-046-049>053-
058.
WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026-
033>036-064-065.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...GRUMM/ROSS
SHORT TERM...GRUMM/ROSS
LONG TERM...STEINBUGL
AVIATION...GRUMM/ROSS
HYDROLOGY...GRUMM/ROSS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
337 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA THIS AFTERNOON
AND TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF
THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID- ATLANTIC COAST.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THE SECONDARY CYCLONE IS OVER SOUTHERN VA AND NORTHERN NC. THIS
LOW SHOULD SLOWLY EVOLVE AS THE PRIMARY CYCLONE OVER THE NEXT
SEVERAL HOURS. THERE STILL INITIAL CYCLONE WEAKENS AND CONTINUES
TO MOVE NORTHWARD THROUGH WV AND SW PA THIS EVENING IT WILL PUSH
SOME O TO 1C AIR ALOFT INTO WESTERN PA. MOST MODELS AND ENSEMBLES
BRING THE LARGE SCALE 0C AT 850 ISOTHERM INTO CENTRAL PA
INDICATING A MIXTURE OVER MOST OF CENTRAL PA FOR SEVERAL HOURS
TONIGHT. SOUTHEASTER AREAS HAVE ALREADY GONE MOSTLY TO FREEZING
RAIN AND SHOULD CHANGE TO RAIN EARLY THIS EVENING. EXACT SNOWFALL
AMOUNTS AND LOCATIONS ARE STILL A BIT IFFY. BASED MAINLY ON
BLENDED QPF AND PTYPE.
WATER VAPOR SHOWS NICE DRY SLOT AND CLEAR SLOT NEAR INITIAL
CYCLONE OVER WV AT 1845 UTC. TO THE NORTH AND EAST OF THE DRY SLOT
IS A FAVORABLE LOCATION FOR PRECIPITATION BANDS TO FORM THIS
EVENING. THIS WOULD FAVOR POTENTIAL PERIOD OF HEAVY SNOW IN
NORTHERN AND NORTH-CENTRAL PA. THE 13KM RAP HAS TRIED TO SHOW A
PIVOTING AREA OF SNOW THIS AFTERNOON INTO THURSDAY MORNING OVER
THIS REGION. THE HEAVIER SNOW FROM CLEARFIELD COUNTY AND NORTHERN
CENTRE COUNTY LOOKS GOOD BASED ON RAP FORECASTS AND THE SATELLITE EVOLUTION.
THE SMALLER WARM POCKET WITH THE INITIAL LOW IS ASSOCIATED WITH
SOME OF THE BRIGHT BAND WE HAVE SEEN OVER W-CENTRAL PA THIS
AFTERNOON. THOUGH DESPITE 2 SURGES OF 50DBZ BB OVER JOHNSTOWN HAS
REMAINED SNOW AT THE SURFACE.
STILL IFFY IN CENTRAL AREAS AS 0C AT 850 HPA IN MOST NCEP GUIDANCE
SHOULD PUSH BACK TO NEAR STATE COLLEGE. HAD TO PUT MIXED
PRECIPITATION OVER MOST OF CENTRAL AND EASTERN AREAS. THE RAP AND
NAM 4KM BOTH SHOW MIXED PRECIPITATION THIS EVENING FROM NEAR STATE
COLLEGE SOUTH AND EAST. GOING TO BE VERY CLOSE IN SOUTHERN CENTRE
COUNTY AND SNOW TOTALS WILL HINGE ON WHEN AND HOW LING IT MIXES.
RAP HAS SHOWN FREEZING RAIN AT TIMES.
IN THE SOUTHEAST RAIN SHOULD DOMINATE MOST YORK...DAUPHIN AND
LANCASTER COUNTIES THIS EVENING AND OVERNIGHT. TEMPERATURES SHOULD
GET IN THE LOWER 40S IN EASTERN AREAS.
WINDS WILL BE MORE A PROBLEM DURING THE DAY THURSDAY WHEN WE LOSE
THE LOW LEVEL STABILITY. THOUGH SOME BLOWING AND DRIFTING SNOW
POSSIBLE AT TIMES OVER NORTHERN AND CENTRAL PA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM.
MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST
MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO
THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY
ISSUED FOR SOUTHERN ZONES. OUTSIDE OROGRAPHIC SNOW AND LAKE EFFECT
SNOW (LES) SNOW AREAS LITTLE SNOW IS FORECAST THURSDAY.
MIXING HEIGHTS AT 4-5K FT AGL WILL BRING DOWN 40-50 KT GUSTS.
MAINLY IN SW MOUNTAINS AND S-CENTRAL PENNSYLVANIA WHERE MODELS
SHOW A FEW HOURS OF 45 TO 60KTS AT 850 HPA.
LAKE EFFECT SNOW SHOWERS WILL ALSO OCCUR IN W MTNS. WINDS WILL
DIMINISH THURSDAY EVENING.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI AS AREA OF
HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL WX INTO FRI
NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM EXPECTED TO
DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION. CONSENSUS OF OPER
MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF PA THRU THE SRN
MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND COAST.
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD
OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV.
CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE
PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST.
WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND
BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA
EXPECTED THIS AFTERNOON AND EVENING.
TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH
FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST.
18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA
MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT.
POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST
CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING.
ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER
LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS
IN THE 1-4KFT LEVELS.
SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST
OVERNIGHT INTO EARLY THURSDAY. ELSEWHERE CONDITIONS SHOULD RISE TO
MVFR AT TIMES BEFORE 12Z THURSDAY.
IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND
BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST
MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH
MOUNTAIN AND LAKE ENHANCED SNOW SHOWERS.
IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING
AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE
MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD
LEAD TO MINOR FLOODING IN THE SOUTHEAST.
AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD
IT GET WARMER AND MORE RAIN IS OBSERVED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006-
010>012-017>019-024>028-033>035-037-041-042-045-046-049>053-
058.
WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026-
033>036-064-065.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...GRUMM/ROSS
SHORT TERM...GRUMM/ROSS
LONG TERM...STEINBUGL
AVIATION...GRUMM/CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
258 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA THIS AFTERNOON
AND TONIGHT. STRONG GUSTY WINDS ARE EXPECTED THURSDAY ON THE BACKSIDE OF
THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID- ATLANTIC COAST.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SNOW RAPIDLY MOVED FROM SOUTH TO NORTH OVER CENTRAL PA THIS
MORNING. STILL HAD NOT REACHED THE NORTHERN TIER COUNTIES AS OF 1
PM BUT SHOULD REACH THE NY BORDER BETWEEN 1 AND 130 PM THIS AFTERNOON.
HEAVIEST PRECIPITATION OVER MOST OF THE REGION EXPECTED FROM ABOUT
NOW UNTIL 6-8 PM.
LOW-LEVEL COLD AIR...IN PART DUE TO EVAPORATIVE COOLING...HAS
SNOW. THE MODELS ALL SUGGEST THE SOUTHERN TIER AND THE SOUTHEAST
SHOULD MIX WITH ICE PELLETS THIS AFTERNOON AND THEN WITH SOME
FREEZING RAIN. WHERE THE 850 HPA WET-BULB ZERO GETS TO THIS
EVENING WILL DICTATED SNOWFALL AMOUNTS OVER CENTRAL AREAS. LOTS OF
UNCERTAINTY. BUT SOUTHEAST SHOULD MIX WITH FREEZING RAIN AND THEN
LANCASTER COUNTY SHOULD GO TO ALL RAIN...MOST OF DAUPHIN AND YORK
COUNTIES TOO SHOULD CHANGE TO ALL RAIN.
THE ICE PELLETS SHOULD MAKE IT AS FAR NORTH AS ALTOONA-STATE
COLLEGE AND WILLIAMSPORT. MUCH NORTH AND WEST OF THERE SHOULD STAY
ALL SNOW. FREEZING RAIN SHOULD GET AS FAR WEST AS LEWISTOWN.
THE RAP CONTINUES TO SHOW A DRY SLOT COMING IN FROM THE SOUTHWEST
THIS EVENING AND AN IMPLIED COMMA HEAD TO BRING MORE SNOW FROM
SOUTHWESTERN AREAS...NEAR JOHNSTOWN AROUND 10 PM WHICH MOVES UP
THROUGH CLINTON AND NORTHERN LYCOMING COUNTIES BY 5 AM. AHEAD OF
THIS FEATURE THE PRECIPITATION COULD TAPER OFF THIS EVENING WITH THE
DRY SLOT MOVING INTO SOUTHERN PA AROUND 7-8 PM AND INTO CENTRAL PA
AFTER MIDNIGHT. THIS COULD PRODUCE SOME FREEZING DRIZZLE IN
SOUTHERN AND EASTERN AREAS WHEN THE SEEDER-FEEDER EFFECT IS LOST.
THE COMMA HEAD IN THE 4KM NAM AND 13KM RAP WILL BRING THE SECOND
SURGE OF SNOW WHICH WILL NEED TO BE MONITORED OVERNIGHT. TEMPS
MAINLY 20S NORTH AND 30S SOUTH AND PERHAPS SOME MID-40S SNEAK
INTO LANCASTER COUNTY.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM.
MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST
MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO
THE EAST. STRONG WINDS WILL BECOME THE BIGGEST ISSUE AND ADVISORY
ISSUED FOR SOUTHERN ZONES. MIXING HEIGHTS AT 4-5K FT AGL WILL
BRING DOWN 40-50 KT GUSTS. LAKE EFFECT SNOW SHOWERS WILL ALSO
OCCUR IN W MTNS. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON
FRI AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY
TRANQUIL WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO
SYSTEM EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION.
CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF
PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND
COAST. IN ANY CASE...THIS LOOK LIKE A LIGHT SNOW FOR MOST OF THE
CWA.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD
OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV.
CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE
PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST.
WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND
BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA
EXPECTED THIS AFTERNOON AND EVENING.
TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH
FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST.
18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA
MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT.
POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST
CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING.
ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER
LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS
IN THE 1-4KFT LEVELS.
SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST
OVERNIGHT INTO EARLY THURDAY. ELSEWHERE CONDITIONS SHOULD RISE TO
MVFR AT TIMES BEFORE 12Z THURSDAY.
IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND
BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST
MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH
MOUNTAIN AND LAKE ENHANCED SNOWSHOWERS.
IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING
AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE
MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD
LEAD TO MINOR FLOODING IN THE SOUTHEAST.
AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD
IT GET WARMER AND MORE RAIN IS OBSERVED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR PAZ004>006-
010>012-017>019-024>028-033>035-037-041-042-045-046-049>053-
058.
WIND ADVISORY FROM 7 AM TO 5 PM EST THURSDAY FOR PAZ024>026-
033>036-064-065.
WINTER WEATHER ADVISORY UNTIL 7 AM EST THURSDAY FOR PAZ036-056-
057-059-063-064.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065-
066.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...GRUMM/ROSS
SHORT TERM...GRUMM
LONG TERM...STEINBUGL
AVIATION...GRUMM/CERU
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1243 PM EST WED DEC 26 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM LIFTING NORTHEAST ACROSS THE CENTRAL
APPALACHIANS AND MID-ATLANTIC STATES WILL BRING SIGNIFICANT WINTRY
PRECIPITATION TO THE MUCH OF CENTRAL PENNSYLVANIA TODAY INTO
TONIGHT. STRONG GUSTY WINDS ARE EXPECTED TOMORROW ON THE BACKSIDE
OF THE DEPARTING STORM SYSTEM. A WEAK AREA OF HIGH PRESSURE WILL
BRING A BRIEF PERIOD OF RELATIVELY TRANQUIL WEATHER ON FRIDAY.
ANOTHER ROUND OF WINTRY WEATHER IS POSSIBLE ON SATURDAY AS LOW
PRESSURE TRACKS NORTHEAST FROM THE DEEP SOUTH TOWARD THE SOUTHERN
MID-ATLANTIC COAST.
&&
.NEAR TERM /THROUGH TONIGHT/...
SNOW RAPIDLY MOVED FROM SOUTH TO NORTH OVER CENTRAL PA THIS
MORNING. STILL HAD NOT REACHED THE NORTHERN TIER COUNTIES AS OF 1
PM BUT SHOULD REACH THE NY BORDER BETWEEN 1 AND 130 PM THIS AFTERNOON.
HEAVIEST PRECIPITATION OVER MOST OF THE REGION EXPECTED FROM ABOUT
NOW UNTIL 6-8 PM.
LOW-LEVEL COLD AIR...IN PART DUE TO EVAPORATIVE COOLING...HAS
SNOW. THE MODELS ALL SUGGEST THE SOUTHERN TIER AND THE SOUTHEAST
SHOULD MIX WITH ICE PELLETS THIS AFTERNOON AND THEN WITH SOME
FREEZING RAIN. WHERE THE 850 HPA WET-BULB ZERO GETS TO THIS
EVENING WILL DICTATED SNOWFALL AMOUNTS OVER CENTRAL AREAS. LOTS OF
UNCERTAINTY. BUT SOUTHEAST SHOULD MIX WITH FREEZING RAIN AND THEN
LANCASTER COUNTY SHOULD GO TO ALL RAIN...MOST OF DAUPHIN AND YORK
COUNTIES TOO SHOULD CHANGE TO ALL RAIN.
THE ICE PELLETS SHOULD MAKE IT AS FAR NORTH AS ALTOONA-STATE
COLLEGE AND WILLIAMSPORT. MUCH NORTH AND WEST OF THERE SHOULD STAY
ALL SNOW. FREEZING RAIN SHOULD GET AS FAR WEST AS LEWISTOWN.
THE RAP CONTINUES TO SHOW A DRY SLOT COMING IN FROM THE SOUTHWEST
THIS EVENING AND AN IMPLIED COMMA HEAD TO BRING MORE SNOW FROM
SOUTHWESTERN AREAS...NEAR JOHNSTOWN AROUND 10 PM WHICH MOVES UP
THROUGH CLINTON AND NORTHERN LYCOMING COUNTIES BY 5 AM. AHEAD OF
THIS FEATURE THE PRECIPITATION COULD TAPER OFF THIS EVENING WITH THE
DRY SLOT MOVING INTO SOUTHERN PA AROUND 7-8 PM AND INTO CENTRAL PA
AFTER MIDNIGHT. THIS COULD PRODUCE SOME FREEZING DRIZZLE IN
SOUTHERN AND EASTERN AREAS WHEN THE SEEDER-FEEDER EFFECT IS LOST.
THE COMMA HEAD IN THE 4KM NAM AND 13KM RAP WILL BRING THE SECOND
SURGE OF SNOW WHICH WILL NEED TO BE MONITORED OVERNIGHT. TEMPS
MAINLY 20S NORTH AND 30S SOUTH AND PERHAPS SOME MID-40S SNEAK
INTO LANCASTER COUNTY.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
CONSIDERING WIND ADVISORY THURSDAY BEHIND THE STORM.
MOST OF THE SNOW AND ACCUMULATING WILL BE IN THE SOUTHWEST
MOUNTAINS AND NW PA THURSDAY. MAINLY SNOW SHOWERS AND FLURRIES TO
THE EAST.
...OLD DISCUSSION...
STRONG GUSTY WINDS ARE EXPECTED ON THE BACKSIDE OF THE DEPARTING
STORM SYSTEM ON THURS. PEAK GUSTS MAY WARRANT AN ADVY AS BUFKIT
MIXING HEIGHTS REACH 4-5KFT AGL AND TAP 40-50KT WINDS FROM THE
NW. THE COLDER AND RELATIVELY MOIST MID-LVL CYCLONIC FLOW SHOULD
ALSO SUPPORT SCT LAKE EFFECT AND UPSLOPE SNOW SHOWERS ACRS THE WRN
MTNS. ADDNL 1-3" ACCUMS ARE LKLY IN THE FAVORED AREAS DOWNWIND OF
LAKE ERIE AND OVER THE RIDGES OF SOMERSET CNTY. THE GUSTY WINDS
MAY ALSO PRODUCE SIGNIFICANT BLOWING AND DRIFTING OF THE SNOWFALL
FROM DAY 1. WINDS AND LES WILL SUBSIDE/GRADUALLY DIMINISH ON FRI
AS AREA OF HIGH PRES PROVIDE BRIEF PERIOD OF RELATIVELY TRANQUIL
WX INTO FRI NIGHT/EARLY SAT. FOCUS WILL THEN SHIFT TO SYSTEM
EXPECTED TO DEVELOP OVER THE DEEP SOUTH/GULF COAST REGION.
CONSENSUS OF OPER MODEL AND ENSEMBLE DATA TAKE THIS STORM SOUTH OF
PA THRU THE SRN MID-ATLC STATES AND EVENTUALLY OFF THE NEW ENGLAND
COAST. DESPITE SOME LINGERING UNCERTAINTIES...A BLEND OF THE NEW
00Z HPC GUID AND EXPERIMENTAL ECMWF MOS SUPPORTS HIGH CHC TO LOW
LKLY POPS ACRS THE SRN TIER ZONES...WITH POTNL FOR LIGHT SNFL AMTS
ON DAY 4/SAT.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE PATTERN LOOKS TO REMAIN AT LEAST SEASONABLY COLD INTO THE NEW
YEAR...ALTHOUGH THE 26/00Z ECMWF MOS NUMBERS ARE MUCH COLDER THAN
THE GFSMEX MOS...SHOWING HIGHS IN THE MID-UPPER TEENS AND LOWS IN
THE SINGLE DIGITS FOR NEXT TUES/WED. DUE TO NEAR/SHORT TERM WX DID
NOT SPEND TO MUCH TIME ON THIS PERIOD AND SIMPLY TOOK A BLEND OF
AVAILABLE GUID.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
THE FIRST BAND OF SNOW AND ICE PELLTS IS WORKING ITS WAY NORTHWARD
OVER SOUTHERN PA. SOME REPORTS OF SNOW FROM KJST EASTWARD TO KTHV.
CIELINGS AND VISIBILTY WILL CONTINUE LOWER AS MORE SNOW AND ICE
PELLETS MOVE IN FROM THE SOUTH AND SOUTHWEST.
WIDESPREAD SNOW EXPECTED IN THE AFTERNOON AND EVENING. WINDS AND
BLOWING SNOW ACROSS MUCH OF NORTHERN AND WESTERN AREAS AREA
EXPECTED THIS AFTERNOON AND EVENING.
TO THE SOUTH AND EAST EXPECT SNOW AND ICE PELLETS TO MIX WITH
FREEZING RAIN BEFORE CHANGING OVER TO RAIN IN THE SOUTHEAST.
18Z TODAY THROUGH AT LEAST 06Z OVERNIGHT EXPECT MAINLY IFR AREA
MVFR. CONDITIONS SHOULD BEGIN TO IMPROVE OVERNIGHT.
POTENTIAL FOR ICING AND THE NEED TO DEICE WILL BE AN ISSUE AT MOST
CENTRAL PA AIRPORTS UNTIL ABOUT 00Z THIS EVENING.
ENTIRE AREA WILL HAVE STRONG LLWS AS NORTH-NORTHEAST AT LOWER
LEVELS WITH MORE SOUTHERLY WINDS ALOFT AND A CORE OF STRONG WINDS
IN THE 1-4KFT LEVELS.
SNOW AND BLOWING SNOW WILL BECOME AN ISSUE AT KBFD AND KJST
OVERNIGHT INTO EARLY THURDAY. ELSEWHERE CONDITIONS SHOULD RISE TO
MVFR AT TIMES BEFORE 12Z THURSDAY.
IMPROVING CONDITIONS EAST OF MOUNTAINS THURSDAY. THOUGH SNOW AND
BLOWING SNOW WILL BE AN ISSUE FROM IN SOUTHWEST
MOUNTAINS...KJST...AND IN THE NORTHWEST...KBFD AREA...WITH
MOUNTAIN AND LAKE ENHANCED SNOWSHOWERS.
IMPROVING CONDITIONS EXPECTED THURSDAY NIGHT INTO FRIDAY.
OUTLOOK...
WED...SIG WINTER STORM WITH LOW CIGS/VSBYS DEVELOPING EARLY. LLWS.
THU...WINDY WITH WINTRY WX DIMINISHING EARLY. SHSN CONTINUE IN N
AND W MTNS. LOW CIGS LIKELY...ESPECIALLY N AND W.
FRI...NO SIG WX EXPECTED.
SAT-SUN...LIGHT SNOW AND REDUCED FLIGHT CATEGORIES POSSIBLE
STATEWIDE.
&&
.HYDROLOGY...
WE SHOULD AVOID FLOODING DUE TO SOME OF THE PRECIPITATION FALLING
AS SNOW AND ICE PELLETS. BUT IF THE WARM AIR GETS FARTHER WEST THE
MELTING SNOW AND APPROXIMATELY 1.5 INCHES OF PRECIPITATION COULD
LEAD TO MINOR FLOODING IN THE SOUTHEAST.
AT THIS TIME OPTIMISTIC THERE WOULD BE ONLY MINOR FLOODING SHOULD
IT GET WARMER AND MORE RAIN IS OBSERVED.
&&
.CTP
WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 AM EST
THURSDAY FOR PAZ004>006- 010>012-037-041-042. WINTER STORM WARNING
UNTIL 7 AM EST THURSDAY FOR PAZ017>019-
024>028-033>035-045-046-049>053-058. WINTER WEATHER ADVISORY UNTIL
7 AM EST THURSDAY FOR PAZ036-056- 057-059-063-064. WINTER WEATHER
ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065- 066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...GRUMM/ROSS
SHORT TERM...GRUMM
LONG TERM...STEINBUGL
AVIATION...GRUMM/CERU
HYDROLOGY...GRUMM