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AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TALLAHASSEE FL
842 PM EST Wed Dec 28 2011


Updated most recently for SYNOPSIS and Near Term sections.

.SYNOPSIS...A fairly potent MID-upper level SHORTWAVE TROUGH was
moving quickly east-southeast this evening through east Texas.
Ahead of the approaching wave, higher clouds were streaming into
the eastern Gulf Coast region. The lower levels of the ATMOSPHERE
across the region were very dry, though, AS sampled by the 00z
soundings. A weak surface HIGH PRESSURE was centered almost
directly on the forecast area with very light winds. Some west-
southwesterly return FLOW was beginning across parts of southern
Louisiana and Mississippi on the back side of the high, but deeper
LOW-level MOISTURE had not made any progress inland in those
areas. Therefore, despite relatively strong forcing for vertical
motion ahead of the approaching wave, limited moisture and weak
WIND fields underneath the low-level high pressure are expected to
keep RAIN chances generally under wraps in the short term.

&&

.NEAR TERM (Tonight)...Most of the near-term grid edits this
evening were focused around TEMPERATURE trends tonight, and then
POPS over the Gulf waters over the next 24 hours. As mentioned in
the "Synopsis" section, there is a potent PV ANOMALY moving into
southwest Louisiana at the moment. Objectively analyzed dynamic
TROPOPAUSE maps suggest that the 1.5 PVU surface could be as low
as 550-600mb with that wave. Therefore, it`s not surprising that
there is a decent amount of forcing for ascent (especially in the
middle and upper TROPOSPHERE) ahead of the wave. This is resulting
in some CIRROSTRATUS pushing in from the west, and IR satellite
suggests this could be fairly thick in spots. Therefore, the
radiational cooling process could be limited by the increased
CLOUD cover overnight. Low temperatures were kept fairly close to
the previous forecast, but FROST wording was toned down, and the
mention of freezing temperatures was removed from the HWO.

Changes to PoPs were made into Thursday, as high resolution model
guidance is insistent on SCATTERED showers developing late tonight
and then pivoting into the western sections of our coastal waters
tomorrow. These showers develop near a subtle surface trough from
near Mobile Bay south into the Gulf, and in an area of increasing
low-level moisture. Indeed, there appears to be some low clouds
(4000 FT ceilings) offshore of Mobile Bay stretching south into
the NC Gulf of Mexico. Some of the PoPs derived from high-res
guidance was as high as the upper "CHANCE" RANGE (40-50%), but we
opted to trend things up from a dry forecast to "Slight Chance"
PoPs (20%) for now. With models keeping most of the SHOWER
activity offshore, we kept rain chances over the water as well.

&&

.SHORT TERM (Thursday through Friday NIGHT)...Moving ahead to
Friday, several models hint at some moisture returning and even
some very light showers moving into the western Florida zones from
the Gulf. The 00z NAM was quite bullish and showed 30 to 50 PoPs
over portions of the panhandle. The 12z NAM backed off somewhat
and shows 20 to 30 PoPs. This seems overdone and have instead just
gone with a silent 10 POP for now and will wait for some more
model consistency before adding mentionable PoPs into the forecast
in that area on Friday. The pattern just does not look too
favorable for precip, and there is no real well defined upper
level shortwave forecast for Friday in that area.

Temperatures are expected to commence a slow warming trend through
the short term after tonight with highs near 70 LIKELY by Friday.


.LONG TERM (Saturday through next Wednesday)...The period will
start our dry and mild through the weekend with surface high
pressure to our east and near zonal flow aloft. MIN TEMPS will be
in the mid to upper 40s with highs in the lower 70s across most of
the forecast area. Prior runs of the GFS and ECMWF (Euro) showed
big differences in their handling of the next trough to amplify
into the east. While the GFS remains a bit more progressive, the
Euro has moved sharply toward the GFS and away from its prior
solutions of cutting off a huge upper low in the vicinity of the
southern Appalachians. This leads to similar timing for the cold
frontal passage, which is PROGGED for Sunday night into early
Monday. The GFS still shows a dry frontal passage, while the Euro
shows a band of frontal PRECIPITATION, which incidentally departs
well before it gets cold enough for anything but rain. Since the
Euro is trending toward the GFS, we will maintain our CURRENT
forecast of a dry frontal passage. However, we do plan on going
below the operational guidance for temps by a FEW degrees to
account for the fact that MOS tends toward CLIMATOLOGY that far
out and the Euro is much deeper with the trough. This all
translates into temps taking a tumble behind the cold FRONT. Highs
Monday will be near to a couple of degrees below NORMAL. Monday
night should see temps well down into the 30s with some areas
dipping below freezing. On Tuesday and Wednesday, we are calling
for MAX temps in the lower to mid 50s north and mid to upper 50s
south. Wednesday morning should see temps a couple of degrees
below freezing. Note that if the current Euro solution verifies
(with 850-MB temps some 8 to 12 degrees below zero), temps will be
significantly colder than currently advertised from Monday night
into Wednesday, certainly low enough for the area to see the first
WIDESPREAD hard FREEZE of the season. Stay tuned.


&&

.AVIATION (through 00z Friday)...VFR is expected to prevail through
the period with some high CIRRUS and light winds. Current
satellite analysis and offshore observations are showing a 3500 ft
cloud deck over the northwestern Gulf of Mexico. This cloud deck
is expected to affect KECP and KDHN during the early morning
hours. No significant ceilings are expected however.


&&

.MARINE...As high pressure builds eastward across the Gulf, winds and
SEAS are expected to remain light through the weekend. Winds and
seas may elevate to ADVISORY levels early next week after the
passage of the next cold front.


&&

.FIRE WEATHER...Much cooler and drier AIR is building into the region
behind the cold front that passed through the area Tuesday
morning. The afternoon relative HUMIDITY is forecast to drop near
35 percent across parts of the Florida big bend and panhandle
today, Thursday, and Friday. However, red flag conditions are not
expected to occur as durations of low relative humidity are
expected to be short.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
842 PM EST Tue Dec 27 2011

.DISCUSSION...00 UTC surface analysis shows a cold FRONT moving off
the Florida East Coast in association with a 993 MB surface LOW
PRESSURE system across Central New York. Cooler AIR continues to
arrive behind the front, but it isn`t appreciably cold with
dewpoints back nearer the HIGH pressure area over Texas only in the
low to MID 30s. So while a cool down is expected here locally,
extremely cold temperatures are not.

Upper air data from 00 UTC and vapor imagery shows a high AMPLITUDE
TROUGH moving through the Ohio and Tennessee River Valleys. The last
IMPULSE to affect our region is at the base of the trough swinging
through Middle Georgia. The local KTAE SOUNDING shows the drier and
cooler airmass that has arrived. The precipitable water value is
down to 0.39 inches and the entire depth of the sounding is colder
than 24 hours ago.

Remaining forecast concern will be the TEMPERATURE forecast.
Lingering STRATUS behind the front will slow the temperature drop
across Southern Georgia, but clearing skies are arriving elsewhere
across the region. The pressure GRADIENT is light, but still some
light winds are expected overnight so the CURRENT forecast MIN
temperatures in the upper 30s certainly looks good and could be just
a tad on the low side. However, given UPSTREAM readings already in
the low to mid 40s will assume temperatures locally will respond
similarly once the lingering CLOUD cover gets out of here after 06z.
Thus, plan on making no changes to the current forecast.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
130 PM EST Mon Dec 26 2011

...Slight CHANCE for Severe Weather Late Tonight into Tuesday
Morning Still Expected in areas of the Florida Panhandle and Big
Bend...including parts of Southeast Alabama and Southwest and South
Central Georgia 20 to 30 miles to the North of I-10...

.SYNOPSIS...Thus far, the 2 most dominant synoptic scale features on
the MAP today are the cold 1030mb SFC RIDGE holding in over the
Lower Tennessee Valley, and our next expected weather maker
currently packaged in a small, but potent Upper Level SHORTWAVE over
the Upper Texas Panhandle. Thus far, there is just a large area of
mainly weak isentropic lift between these 2 systems, which is
creating a sizable area of mostly light to moderate RAIN with a FEW
embedded thunderstorms over eastern TX, much of LA, MS, and parts of
western AL. This PRECIPITATION will be gradually heading our way
tonight and possibly with a more formidable line of showers and
thunderstorms (some of which could be strong to severe closer to the
coast), AS Sfc Based CYCLOGENESIS begins to take place out ahead of
the vigorous shortwave.

&&

.SHORT TERM (Tonight through Wednesday NIGHT)...As mentioned above,
it appears that the only sensible weather which will occur during
the short term period will be tonight into Tuesday, before much
cooler and drier AIR builds into the region behind the fast moving
cold FRONT from Tuesday night onward. HIGH Temperatures could be
relegated to the upper 50s to lower 60s on Wednesday, with some
indications of a possible light FREEZE over parts of the interior on
Wednesday Night. Back to the potential severe weather event, it
appears that very little has changed in both areal thinking (mainly
in areas just to the north of I-10 into SE AL and extreme SW GA, then
extending to all points to the south and west), and that the overall
potential will remain slight. However, one component that may be
changing slightly is the timing of the threat, which overall appears
to be quickening just a bit with each successive model run.
Therefore, we now believe it is becoming more LIKELY that the window
of opportunity for any severe weather will likely have shifted to
the east of our CWA during the afternoon., as winds shift quickly to
the NW behind the Cold Front.


.LONG TERM (Thursday through next Monday)...A weak short wave will
move across the local region on Thursday. However, the  ATMOSPHERE
will be too dry to support much in the way of clouds let alone
RAINFALL. Another lobe of energy will pass overhead Friday night
into Saturday and again with little or no impact. The next and most
impressive in the series of short waves is forecast to arrive during
the Sunday to Sunday night time frame. Currently this feature shows
enough upper support and available MOISTURE to bring a LOW end
chance of POPS to start the new YEAR. A cold front is also forecast
to push through the Tri-state region and usher in a much drier and
cooler airmass to start next week. TEMPS will be below seasonal
levels Thursday and Friday with freezing or near freezing temps
Thursday morning. MAX temps will moderate from the lower 60s
Thursday to the upper 60s and lower 70s Friday through the weekend
and then dropping back down into the lower to MID 60s on Monday.

&&

.MARINE...Although wave heights will certainly be lower over
Apalachee Bay, as they always are due to it`s shallow BATHYMETRY,
there appears to be little doubt that SCA level winds will at least
exist here for a portion of the time in association with this
developing Low PRESSURE System. Therefore, will upgrade this section
of the Coastal Waters to a Small Craft ADVISORY this afternoon,
which should allow us to trim the CWF back to two segments. This
will also be a small and fast moving Low Pressure system so boating
conditions should improve behind the front Tuesday Night and
especially by Wednesday Morning.

&&

.AVIATION...Cigs ranging from VFR to MVFR are expected to persist
for the remainder of the afternoon hours ahead of an approaching
cold front. Conditions will deteriorate later tonight as the front
moves into the area. Showers and a few thunderstorms are expected to
overspread the region from west to east. Easterly winds around 10
knots are expected for the rest of the afternoon, then VEERING to a
more southerly direction and increasing some tonight ahead of the
front. Low level WIND SHEAR is expected to become a concern later
tonight as a strong southerly low level JET develops ahead of the
cold front.

&&

.FIRE WEATHER...Although a fairly strong cold front will move
through late tonight and into Tuesday, long durations of low
relative HUMIDITY values are currently not expected behind it. We
may briefly approach 35 percent across portions of northwest Florida
on Wednesday afternoon, but the lack of any strong winds, high
dispersions, or high ERCs at that time is expected to prevent red
flag conditions.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
835 PM EST Thu Dec 22 2011


SHORT TERM  (Friday through Saturday NIGHT)...
There is likely to be a band of showers at the beginning of the
period (Friday morning) that will slowly sink south across the area.
This should be the remnants of the showers and thunderstorms that
will be ongoing along and behind the surface cold front this
afternoon and tonight. This front will slowly stall out and lose its
character. The fast-moving shortwave trough associated with the
frontal system today will be moving off to the northeast, with the
overall upper level FLOW pattern rather unchanged (large RIDGE over
the Caribbean, Bahamas and south Florida, and WSW flow aloft).
Therefore, there should be very little upper level support to get
the front much past our forecast area. As NVA sets in aloft and
mid-upper level heights rise slightly into Saturday, the rain
showers should gradually diminish. By Saturday we should have partly
CLOUDY skies with a drier period, before the next shortwave ejects
to the east. To sum it up, tomorrow should be relatively cloudy with
some periodic light showers, followed by drying Friday Night and a
dry and pleasant forecast for Saturday. With no major model
differences of note, a broad consensus was used. No THUNDER was
included in the sensible weather as model forecast instability is
either non-existent or below 100 j/kg.

.LONG TERM (Sunday through next Thursday)...
The large scale longwave pattern commences rather amplified
highlighted by ridging over WRN states...large positively tilted
trough across much of rest of country with axis from Great Lakes
SWWD into Old MEX with nearly CUTOFF low over SW most TX/Old Mex
border, and a strong H5 ridge over S FL with an ANTICYCLONE
centered over the Bahamas. Impulses assocd with low will lift and
move rapidly into NRN stream trough across Great Lakes and combine
with shortwave diving from Canada into East Coast to begin to
deepen NE trough and suppress FL ridge SEWD. At surface, low over
Nrn GA with warm front EWD into Atlc and trailing cold front
across Wrn CWA. Local forecast area remains under an ACTIVE SWLY
flow aloft, as well as a broad warm sector with SLY low level flow
ahead of front with OVERRUNNING rain behind locally yielding a
continuation of ample MOISTURE return and beneficial mainly
STRATUS precip and embedded showers to begin the period. Also with
DEW points into the mid 60s and a slow moving front, the strong
possibly of FOG exists especially at night. With DEEPENING ERN
trough, Front will finally move THRU in fits and starts during
Sunday but will have no upper support and so no threat for strong
to severe storms.

However, forecast remains tricky as models continue to diverge on
timing of impulses and how fast to bring front across so which model
wins out will noticeably impact POPS/TEMPS. Beginning Monday, the
GFS much more bullish on drying us. ECMWF much slower with frontal
passage and keeping post frontal moisture around so overall
confidence past Sunday remains not HIGH until I see better model
agreement. Best forecast is that the TX upper cutoff low will
continue to lift NEWD, fill and open into a wave with flow across SE
region becoming more zonal. However, the above Canadian shortwave
with phase with one moving across Gulf to further carve out a trough
along the NE Coast especially if ECMWF verifies. Either way, in WAKE
of front, brief drying commencing on Monday from NW-SE. However, yet
another albeit weak shortwave tracks ewd across mainly FL zones and
coastal waters on Tuesday and brings a small CHANCE of rain. Then, a
large area of CP high PRESSURE builds SWD thru the Plains and into
SE states promoting STABLE conditions, a drier airmass and cooler
temperatures for remainder of period.

Will go mid SCT pops SAT night thru Sun. low sct FL zones on Tues,
otherwise WDLY sct or below rest of period. In warm sector...MIN
temps remain around 5 to 10 degrees above CLIMO thru at least Sat
night dropping to slightly above climo rest of period. MAX temps
will hover around climo Sun-Tues than increase to up to 5 degrees
above climo Wed and Thurs. AVG inland min/max temps around 40/63
degrees).

For a morning, the sky looked like a surfer’s dream: A series of huge breaking waves lined the horizon in Birmingham, Ala., last Friday, Dec. 16, their crests surging forward in slow motion. Amazed Alabamians took photos of the clouds and sent them to their local weather station, wondering, “What are these… Tsunami clouds?”

Experts say the clouds were pristine examples of “Kelvin-Helmholtz waves.” Whether seen in the sky or in the ocean, this type of turbulence always forms when a fast-moving layer of fluid slides on top of a slower, thicker layer, dragging its surface.

Water waves, for example, form when the layer of fluid above them (i.e., the air) is moving faster than the layer of fluid below (i.e., the water). When the difference between the wind and water speed increases to a certain point, the waves “break” — their crests lurch forward — and they take on the telltale Kelvin-Helmholtz shape.

According to Chris Walcek , a meteorologist at the Atmospheric Sciences Research Center at the State University of New York, Albany, fast-moving air, high in the sky, can drag the top of slow-moving, thick clouds, underneath it in much the same way.

“In the pictures of the Birmingham sky, there is probably a cold layer of air near the ground where the wind speed is probably low. That is why there is a cloud or fog in that layer,” Walcek told Life’s Little Mysteries, a sister site to LiveScience. “Over this cloudy, cold, slow-moving layer, is probably a warmer and faster-moving layer of air.”

Most of the time, the difference in wind speed and temperature between two layers of the atmosphere is small, and so the fast-moving air on top “simply slides smoothly over the slower-moving air… like a hockey puck sliding along an ice surface,” Walcek said. At the other extreme, if the wind-speed difference is too large, the interface between the two layers breaks down into random turbulence.

Kelvin-Helmholtz waves form when the difference in the temperature and wind speed of the two layers hits a sweet spot. “What these pictures show is air between these two atmospheric layers that is just very close to that threshold for turbulence, and mixing the two layers together,” he said.

This story was provided by Life’s Little Mysteries, a sister site to LiveScience. Photos from Birmingham’s ABC 33/40 viewers.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
205 PM EST Mon Dec 12 2011

.NEAR TERM (through tonight)...
We may see some breaks from time to time but for he most part we are
expecting the persistent LOW level cloudiness to remain with us at
least through daybreak Tuesday. POPS have been reduced to silent 10%
overnight AS the upper level disturbance and deep layer MOISTURE has
now moved east of local region. The moisture that remains in place
in the from of STRATUS is shallow and only a FEW light sprinkles or
DRIZZLE will be possible. Patchy FOG is also possible overnight due
to all the residual moisture from the WIDESPREAD rains of the past
24 hours. Winds will be from the east to northeast 5 to 10 mph so
widespread dense fog is not expected. MIN TEMPS will be similar to
this morning ranging from MID 40s northern zones to lower 50s along
the coast and southeast Big Bend.

.SHORT TERM (Tuesday through Wednesday NIGHT)...
The upper low off the CA coast will swing inland over the northern
Baja just south of San Diego Tuesday morning and then move eastward
across the Desert SW through Wednesday before beginning to SHEAR out
into the Southern Plains. in response, the DOWNSTREAM RIDGE will
build eastward over the southeastern states. The surface HIGH over
the Mid Atlantic states will move little through Wednesday morning
and then begin to slip southward in response to an approaching cold
FRONT. The rising heights will bring a warming trend to the area,
especially once the clouds vacate tomorrow afternoon. Highs will be
4-5 degrees above NORMAL on Tuesday and 8-9 degrees above normal on
Wednesday. Morning lows will be mild in the mid to upper 40s north
and upper 40s to lower 50s south.

.LONG TERM (Thursday through next Monday)...
No major changes were made to the long term forecast tonight as
compared to the forecast that was prepared last night. A ridge that
will be expanding over the east coast at the beginning of the period
should place us squarely in an area of above normal temperatures.
The positive low-level TEMPERATURE and upper-level HEIGHT
anomalies associated with this expanding ridge are expected to
persist, more or less, through the period. Therefore, we
maintained the above normal temperatures through next weekend.
RAIN chances were once again kept very low, below 15% except in
the far north on Friday and into early Saturday when a weakening
cold front will be stalling out somewhere nearby. The associated
upper level low will be located well northeast of the area, and
thus there is not expected to be much support and deep layer
forcing for widespread PRECIPITATION over our forecast area.

&&

.MARINE (Tonight through Saturday)...
High PRESSURE north of the area will maintain a tight enough
pressure GRADIENT across the waters that the exercise caution winds
observed today and will continue for the most part through Wednesday
night. By Thursday, the high will have settled southward to a
position off the Carolina coast and winds will subside to 10 knots
or less and veer to the southeast. These conditions will then
persist into the weekend.

&&

.AVIATION (through 18Z Tuesday)...
Low level moisture continues to be trapped under a strong INVERSION
currently around 1500 feet. This may elevate somewhat this afternoon
but we still believe that cigs will remain at MVFR levels for the
remainder of the day and lower once again to IFR levels later this
evening and overnight. There may also be periods of LIFR cigs/vsbys
in the pre-DAWN hours, especially at VLD. A return to VFR conditions
at all TAF sites is expected shortly after SUNRISE Tuesday.

&&

.FIRE WEATHER...Minimum relative HUMIDITY values are forecast to be
above critical levels throughout the remainder of the week. There
are no fire weather concerns at this time.

&&

.HYDROLOGY...A few corridors of heavy rain overnight prompted the
issuance of several FLOOD Advisories. The Tallahassee area was
directly impacted by one area of heavy rain, with widespread 3 to 5
inch totals across various parts of the Big Bend (heaviest totals
generally south and west of Tallahassee). The airport ASOS (KTLH)
picked up 3.57 inches, and this is the highest 2-day RAINFALL total
measured at Tallahassee since January 20-21, 2010. Flooding issues
around the city were mainly related to some minor urban flooding and
some shallow water over a few roads. Another corridor of heavy rain
developed from north central Taylor County into central Madison
County, FL. A 5.25 measurement in Madison County was the highest
received for the event. The KTLH RADAR estimated 4 to 7.5 inches of
rain in a narrow band in this area, and radar rainfall estimates
were pretty reliable overnight based on observed rainfall. A quick
survey of area river gages shows that much of this rainfall was
absorbed by the ground with minimal rises observed on area rivers.

Thanks to June Sims in Mossy Head, Florida, for this great rainbow from around 4pm Tuesday.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
230 PM EST Mon Dec 5 2011

.SHORT TERM (Tuesday through Wednesday night)...
A long wave trough with a strongly positive TILT will extend from
northern Quebec SWWD to the American Desert SW at the start of the
period. A DOWNSTREAM RIDGE will remain parked over the FL peninsula.
Surface high pressure will be centered SE of New England and
continue to ridge swwd to FL. A slow moving cold FRONT will extend
the LENGTH of the Appalachians and then swwd across AL to the N.
Central Gulf of Mexico. We continue to see differences among the
various models on the speed with which energy in the southern
portion of the long wave trough will progress eastward across the
southern U.S. This also maintains differences in the timing of the
cold frontal passage. The 00Z Euro is on the fast side of the models
with the 12Z NAM on the slower side. The GFS will be used as a
compromise. Regardless of which model verifies best, the progress of
the front should be pretty slow. We also anticipate some
post-frontal precip with this system. Deep layer WSW winds aloft
over the warm sector will warm the mid levels and limit instability.
Therefore, little to no thunder is expected and none is included in
the forecast.

Looking at specific TEMP/POP trends, substantial differences can be
expected at times across the forecast area. TEMPS should remain
uniformly mild mild to warm across the region on Tuesday with highs
in the mid 70s for most areas and upper 70s to around 80 over VLD
and the eastern FL Big Bend. POPS will range from LIKELY NW to
slight CHANCE SE. The front will begin to work its way slowly
eastward across the CWA Tuesday night. Temps will remain mild ahead
of it with lows in the 50s and 60s. Another round of fog is possible
ahead of the front across the eastern zones. On Wednesday, the front
will continue its trek across the area, but it will take until
evening to clear the Suwannee River. PoPs will range from likely N
to chance S. There will be quite a range in temps with S. Central GA
and the eastern Big Bend counties getting into the mid to upper 70s
once again and those stuck behind the cold front over SE AL and the
central FL Panhandle seeing little rise in temps during the day.
Depending on frontal timing, areas of light RAIN will come to an end
Wednesday night, although the CURRENT forecast allows a slight PoP
to linger into Thursday morning. MIN temps will get as low as the
mid 30s by around 12Z Thursday over the NW zones with lower to mid
40s to the SE.

.LONG TERM (Thursday through next Monday)...
The models are now in much better agreement on the timing of the
next low pressure system to impact the local region. The 12z ECMWF,
12z Canadian and 00z GFS show the cold front passing through all but
our easternmost zones at the beginning of the extended period. By
daybreak Thursday the front is forecast to be over or just south of
Cross City. Will hold on to a slight PoP across the Big Bend and
Valdosta regions Thursday morning to account for the system
possibly lingering a bit longer. After the SHORTWAVE and associated
cold front pass, additional shortwave energy will rapidly drop to
the southeast from the northern plains allowing a trough to dig
across the eastern U.S. This will send a dry cold front through the
Tri-state area over the weekend bringing with it a re-enforcement of
cold dry AIR. Temperatures will be below seasonal levels throughout
the extended period with freezing or near freezing min temps
possible for Sunday morning.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
820 PM EST Fri Dec 2 2011

.SYNOPSIS...
AT UPPER LEVELS...
The large scale longwave pattern is highlighted by a deep positively
tilted TROUGH over WRN states with 550dm closed LOW over AZ...a deep
layer RIDGE over CNTRL states...SE region and adjacent Wrn Atlc, and
a trough over NE states. RUC shows a deep water vapor return from
the Gulf of MEX along wrn periphery of ridge along Wrn Gulf but
clouds should remain west of local area. All this translates to
continued FAIR, dry and cool weather over NE Gulf region. This
reflected in area 00Z RAOBS. i.e. TAE with 0.17 inch PWAT with light
ENE FLOW below and WNW winds above H6.

During the next 24 HRS, AZ low will deamplify AS it accelerates NEWD
THRU NM...CNTRL Plains reaching Upper MS Valley/Upper Great Lakes
early Sunday. Parent trough will deepen EWD. This allows for the
building of DOWNSTREAM ridge from Yucatan NEWD thru Gulf of Mex and
into N FL and SE region with rising heights and warming TEMPS.

AT LOWER LEVELS...
HIGH PRESSURE centered over SRN Great Lakes dominates SE region
maintaining a NE flow. Looking UPSTREAM, main feature is low over
Cntrl Canada with trailing FRONT SWWD over Plains to low over NEB.
By early SAT...low shifts newd shift front ewd now extending from
Upper Great Lakes swwd thru MO and W TX by early sat.

A warming trend is forecast for the rest of the weekend as the high
moves into New England overnight and drifts off coast during Sat and
Sun before ridging SSW down ERN seaboard and into SE coastal area
tightening local gradients and VEERING winds to produce BREEZY
northeast to east flow. This will also bring some low level MOISTURE
WWD from the Atlc.

&&

.NEAR TERM...(Rest of Tonight into early Saturday)
High pressure remains the dominant feature in the local weather
pattern. The ridge is forecast to shift more NE of the area
overnight, which may allow just enough of a light breeze at times to
keep temperatures from falling as much as last NIGHT. As a result,
we are not expecting a WIDESPREAD FREEZE, although with inland DEW
points in the low to MID 30s and LIKELY light winds and clear skies,
areas of FROST are still likely in the typically colder locations
away from urban areas.
.SHORT TERM...
(Saturday through Monday) A deep layer ridge will remain situated
along the U.S. east coast through Monday, resulting in a
continuation of the FAIR weather of the past few days. After one
more potentially frosty morning Saturday, a warming trend will
begin in earnest. Lows will be in the 40s Sunday, and around 50 on
Monday. Highs will be near average levels (upper 60s north and
at the beaches, lower 70s south) Saturday, lower to MID 70s
Sunday, and mid to upper 70s Monday (with the SAME TEMPERATURE
distribution mentioned for Saturday).

.LONG TERM...
(Monday night through next Friday) The extended period begins with
a broad, positively tilted, upper level TROUGH covering the
entire country (with the exception of the extreme southeastern
U.S.). At the surface, a southwest to northeast extending surface
ridge covers the eastern part of the country with a surface LOW
across the northern Great Lakes and Ontario. A frontal boundary
extends southwest from the aforementioned surface low, into a
surface trough over the Deep South.

As the upper level trough holds its position, deep layer meridional
FLOW will prevent the surface FRONT from moving too quickly east.
It won`t be until sometime around Tuesday afternoon, when a
SHORTWAVE diving out of the northern Plains helps advance the
entire system eastward, pushing the front through our area and
drying us out by Wednesday afternoon.

No severe weather is expected with this system, in fact we may not
even see any THUNDERSTORM development over land as INSTABILITY is
severely lacking. Additionally, with the best DYNAMICS not quite
aligned with the surface front, expect the front to weaken as it
approaches, and passes over our area. This means very limited
RAINFALL for us as well. At this time, guidance suggests around a
half of an inch for our western counties, and less than a quarter
of an inch likely for counties east of a line from Albany south
to Tallahassee.

Temperatures will be moderated by easterly, followed by southerly,
flow before the frontal passage. Expect above average temperatures
with highs in the 70s and lows in the 50s. Behind the front,
temperatures will FALL into the 30s once again.
&&

.AVIATION...VFR conditions will prevail. Winds will shift to
easterly tomorrow as the high pressure area nears the Mid Atlantic
Coast.

&&

.MARINE...The PERSISTENCE of the high pressure ridge situated along
the U.S. eastern seaboard will maintain a rather tight pressure
GRADIENT over the coastal waters through Monday. At 8 PM EST
offshore buoys already around 15 knots and should increase to SCEC
levels before midnight. So exercise caution has been headlined for
rest of tonight for all but the Apalachee Bay. Winds will peak
perhaps late Saturday night or early Sunday with marginal ADVISORY
winds (around 20 KT) over portions of our coastal waters. Otherwise,
winds will continue to straddle the exercise caution threshold
through Saturday evening.