Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/10/16
Area Forecast Discussion...Updated
National Weather Service Billings MT
757 PM MST Fri Dec 9 2016
Further adjustments to highlites with this update. Added the
Bighorn mountains and northern/eastern Carbon county to the going
Winter Weather Advisories. Radar has shown a pretty strong snow
band from Cooney reservoir east through Fromberg and Bridger over
the past hour or so. Models fill this area in with snow overnight
so expect poor travel on US212 all the way from Red Lodge into
Laurel tonight. For the Bighorns the westerly flow pattern isn`t
a great snow producer, but this atmospheric river pattern should
have enough moisture to overcome the inherent downslope off the
mountains to the west. In addition expect gusty winds to create
some significant blowing and drifting issues overnight into
tomorrow morning. So issued advisory for 4 to 6 inches of snow
combined with blowing and drifting snow problems along US14 over
Updated precipitation chances to categorical values generally west
of a Hysham to Sheridan line. 00z NAM and HRRR have been
increasing precipitation amounts over this area and radar supports
this trend. Have a bit of a concern about the area right along the
northern Beartooth foothills where radar has been showing a good
downslope shadow so far. Its possible that this feature will
persist tonight and that snow band currently setting up from
Fishtail to Cooney reservoir and Bridger will be the main
precipitation producer leaving Red Lodge and Nye with just a
dusting. Still seeing some decent dynamics aloft to support some
snow though along with some slop over from the upslope into the
Cooke City area so kept high pops but lowered snow amounts right
along this area, and further lowering may be needed if this
downslope signature persists.
Latest NAM and HRRR showing axis of best snow from Livingston to
Billings overnight into tomorrow afternoon. Already snowing
moderately at times in Livingston. Radar has shown snow in the
vicinity of Billings the past hour or so and expect snow to get
going in central areas in the next hour or so. Heaviest
accumulations for western areas is from now through sunrise,
central zones from midnight through late morning.
Temperatures over western zones are near their lows already and
should see a gradual rise overnight. Areas at 6000 feet are
currently in the single digits there but climb to 7500 feet and
temps are in the mid 20s. May see a few degrees of cooling in
central zones thanks mainly to evaporative cooling as snow
develops, then a rise by sunrise into the teens in many areas.
Eastern zones will stay mainly in the single digits above and
below zero with a few teens below around Fallon county. Chambers
.SHORT TERM...valid for Sat and Sun...
The first wave of energy is still lingering across Musselshell,
Treasure, and Rosebud counties. The next impulse of energy is
working into western Montana. As this wave moves into the area,
expect snow to spread across the area overnight. Lower elevations
will see an additional 1 to 2 inches of accumulation through
tomorrow afternoon. The foothills will see 3 to 4 with the high
mountains getting up to 6 to 10. This will result in roads
continuing to be snowpacked, especially the less traveled roads.
Given the accumulations and the snow cover on roads, will continue
the Winter Weathe Advisory through tomorrow afternoon.
Through the day tomorrow, warmer west winds will begin to shift
east towards Billings. As it does, expect the snow to decrease and
temperatures to increase into the 20s. Sunday should be drier and
warmer. Much of the area will see temperatures in the 20s to near
.LONG TERM...valid for Mon...Tue...Wed...Thu...Fri...
Not a lot of changes were made to the extended forecast.
Uncertainty is still very high in the global models after Tuesday
morning. While the details of the forecast (especially snowfall)
are very cloudy right now, it does appear the trend of cold
temperatures will continue through next week.
Extended begins with another arctic cold front pushing south
through the forecast area early Monday. A good feed of pacific
moisture in the westerly flow aloft will setup a good overrunning
situation (moisture forced to rise over the wedge of arctic air) and
give the region another good shot of snowfall around 1-2 inches
(2-4 in the mountains) beginning Monday morning. Snowfall will
taper off overnight Monday into Tuesday morning. After a mostly
quiet Tuesday (expect for some mountain snowfall), big differences
in the models begin to appear.
The source of these differences arise from the handling of a cut-
off upper level low off the Western US, and its interaction with a
large upper level low over northern Canada. The GFS and Canadian
keep the pacific low weaker, and allow a drier northwest flow to
preside over the region through at least Thursday night. The EC
solution has a stronger cut-off low in the Pacific, and a weaker
upper level low in Canada, this setup results in wetter westerly
flow over the region, and allows much better chances for snow late
Wednesday night into Thursday. While the details are sketchy at
this point, it certainly lent at least a mention of snow in the
forecast for Thursday based on these differences.
Looking to the end of next week and into next weekend, the global
models indicated another disturbance crossing the region, and another
shot of snow. Timing differences are quite large with this system however.
EC gets the snow going again on Friday while the GFS and Canadian
are much slower. Either way, the extended period continues to look
unsettled and cold. This is supported well by the model
Snow will continue to overspread the region this evening and
overnight into Saturday bringing generally MVFR to IFR conditions
with LIFR possible under the heaviest snow. Mountain obscurations
will be prevalent through the TAF period and MVFR/IFR conditions
wont improve to VFR until after 12z, and from west to east. KMLS
and KSHR should stay VFR through this system, though isolated MVFR
in a quick snow shower is certainly possible Saturday morning. Dobbs/STP
.PRELIMINARY POINT TEMP/POPS...
Sat Sun Mon Tue Wed Thu Fri
BIL 004/022 012/030 006/010 901/011 902/014 901/013 902/006
+8/S 31/B 25/J 41/B 10/U 12/J 33/J
LVM 006/033 017/031 014/020 003/014 902/014 002/015 901/003
+8/S 42/S 35/J 42/J 11/U 12/J 33/J
HDN 003/023 009/030 007/012 903/013 907/014 905/014 904/007
88/S 41/B 24/J 21/B 10/U 01/B 33/J
MLS 902/013 001/022 002/004 905/011 904/012 904/012 905/006
45/S 31/B 34/J 21/B 10/U 01/B 33/J
4BQ 901/020 006/027 005/010 904/012 903/013 902/014 902/007
33/S 41/B 13/J 21/B 10/U 01/B 33/J
BHK 909/008 902/017 902/001 907/007 904/006 906/006 906/001
24/S 41/B 24/J 11/B 11/B 01/B 23/J
SHR 008/028 014/030 011/015 903/009 905/012 902/014 904/005
33/S 52/S 24/J 32/J 10/U 01/B 33/J
MT...Winter Weather Advisory in effect until noon MST Saturday FOR
Winter Storm Warning in effect until 6 PM MST Saturday FOR
WY...Winter Weather Advisory in effect until 6 PM MST Saturday FOR
Area Forecast Discussion
National Weather Service State College PA
1012 PM EST Fri Dec 9 2016
In the mean the next 8 days will be dominated by an upper level
trough. The initial trough will move to our east this weekend as
will the massive cold surface high. A wave to our west will bring
snow and a wintry mix to the region Sunday into Monday ahead of a
weak cold front. By midweek another surge of arctic air will
approach the region. This system will likely bring some snow and
potentially one of the coldest air masses to invade our region
since the winter of 2015. The 850 mb temperatures could be in the
-20C range by Thursday and Friday. Next week could end on a frigid
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
Another update for all elements. Most areas will remain cloudy to
Radar shows snow bands over central areas weakening. Band that
came through our office gave us a dusting. Most of the
accumulating snow will be in the northwest. The HRRR keeps snow in
Warren County overnight with the potential in the extreme
northwestern part of the county for another 4-8 inches of snow
before all is said and done. Grids were nudged with HRRR QPF to
get numbers close to this. The blends were much lower than the
Overall a cold night. Snow showers mainly in northwestern areas
and some lighter snow in central and southwestern mountains. Most
accumulating snows in northwestern areas closer to the lake.
Overnight lows mainly teens and 20s.
.SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
The HRRR was used to show the snow lingering into the day and the
total snow is likely 4-8 as stated above. Most of this should
fall before 7 AM Saturday morning. Perhaps 1-3 will fall in this
period as things wind down.
To the south and east a quieter and sunnier day. Still quite cold.
Most areas will be several degrees warmer than Friday was and
there will be less wind. Always a plus when the wind is light.
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
We modified the Sunday into Sunday night forecast with the new
guidance. This produced faster onset of the warm advection induced
snow. Some models are very fast with light snow in western areas
before sunrise Sunday. We blended the superblend and some slower
guidance to compromise. But snow will spread west to east Sunday.
It gets really complicated as nearly all forecast systems show
some accumulating snow potential but, all show the surge of the
850 hPa 0C line into southwestern PA Sunday afternoon/evening and
into north-central areas overnight Sunday around midnight or so.
It is possible northwestern areas will never get that warm.
Thus had to show mixing snow to ice pellets in southwest and then
southeast. Could be some freezing rain. It is too early to get to
specific as there is considerable uncertainty. But at this time it
is sufficient to acknowledge the potential of snow likely changing
to a wintry mix and probably all rain in the southeast early
Monday. The cold air comes in during the day Monday into Monday
evening to change lingering rain and wintry mix to snow as it
Temperatures behind the front Monday into Tuesday are close to
A bit cooler than normal temps indicated early next week, but
longer range models indicate a significant cold front passage
Wed with noticeably below normal temps filtering in for the rest
of next week. Ahead of the arctic surge expected later in the week
there could be another QPF event. Potentially mostly snow in
central and western areas. But the GEFS shows some -18 to -20C air
at 850 hPa with the cold front. About 3-5C colder than the airmass
we had come through today.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Bands of lake effect snow showers will continue overnight into
Saturday morning. Conditions will improve during the afternoon, as
warming aloft occurs and winds shift more to the west and
As of 6 PM, still an band of heavier snow showers from near
BFD to just southwest of IPT. Expect a wide range of conditions
overnight at BFD and JST. UNV and AOO should be VFR for much of
the period. VFR conditions expected at IPT, MDT, and LNS.
Earlier discussion below.
Low pressure tracking from the lee of the Rockies to the Ohio
Valley will bring a broad area of snow/rain to the area Sunday
into early Monday.
Sun-Mon...Widespread MVFR/IFR in snow/rain. Becoming breezy Monday
night with snow showers over the wrn 1/3.
Wed...More snow showers possible.
Lake Effect Snow Advisory until noon EST Saturday for PAZ005.
Lake Effect Snow Warning until noon EST Saturday for PAZ004.
Area Forecast Discussion
National Weather Service Wichita KS
834 PM CST Fri Dec 9 2016
Issued at 831 PM CST Fri Dec 9 2016
Updated to increase cloud cover tonight and especially Sat and to
increase mins over se KS.
Short term models have been fairly consistent in lifting another
swath of low clouds north across the area Sat morning and leaving
them in place through at least mid afternoon. So went ahead and
increased cloud cover for mainly the 12-21z Sat time frame. With
low clouds sticking around se KS most of the night, lows may not
fall off as much as previously expected. So raised them a few
.SHORT TERM...(This Evening through Monday Night)
Issued at 340 PM CST Fri Dec 9 2016
The thermostat will get turned up considerably for as the inverted
surface ridge continues to be pushed east forming a secondary high
pressure center over the Ohio Valley, the Front Range surface
cyclone will strengthen further to produce stronger southerly flow
across central third of the CONUS. The afore-mentioned surface
cyclone is still scheduled to move east into KS and Western OK on
Sunday. Such behavior would produce a sharp moisture axis that`ll
be aligned from TX, thru Eastern OK, to along the KS/MO state line.
A relatively weak mid-level shortwave moving quite rapidly east
across the Northern and Central Plains will then push a cold front
SE that should extend from near the Mid-Mississippi Valley to the
Central Red River by Sun Evening. Areas of light rain and drizzle
will develop across Eastern KS and most of MO on Sun but will end
by Sun Evening as weak surface high pushes SE into KS Sun Night &
early Mon Morning.
Mon & Mon Night:
With a progressive pattern in place the surface high will scoot
east, crossing the Mississippi Valley around noon. This allow
southerly winds to quickly return to KS to produce one more day of
somewhat balmy weather.
.LONG TERM...(Tuesday through Friday)
Issued at 340 PM CST Fri Dec 9 2016
Highlight: Another blast Arctic air set to invade the neighborhood.
A vicious polar vortex will push eastsoutheast across Central
Canada on Tue and intensify further as it crosses Ontario Wed and
Wed Night. This would enable another shot of Arctic air to invade
the region. We will "chill out" the most Wed and Wed Night with
highs struggling to reach the mid 20s and lows from 10 to 15,
respectively. Wed may be especially nasty as Northerly 15 to 25
mph winds would certainly put a bite into us. Some post-frontal
light snow will spread across KS late Tue Night and Wed but little
accumulation should result.
All will be quiet as strong high pressure dominates. If the ECMWF
verifies with a more dynamic pattern, i.e. a MUCH STRONGER Arctic
High centered over the Upper Mississippi Valley with a VERY INTENSE
cyclone over the Southern Rockies, Southern KS may see a thaw on
Fri where a more southerly lower-deck flow would reside.
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 533 PM CST Fri Dec 9 2016
Main aviation concern will be the behavior of stratus through most
of this taf period.
3,500-6,000ft stratus deck that has lingered across the area most
of the day is starting to move out of the western fringes of the
forecast area. Should continue to see clearing on the western
fringes this evening, clearing out of KICT by 02z. After this
evening, confidence in stratus drops significantly. HRRR, RAP and
NAM bring another surge of stratus up by late Sat morning,
encompassing the entire forecast area by the afternoon hours. With
a few models agreeing on this solution, will go with at least a
broken deck most of the day Sat but will keep at VFR levels until
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 20 45 34 48 / 0 0 0 10
Hutchinson 19 44 32 45 / 0 0 0 10
Newton 20 42 33 44 / 0 0 0 10
ElDorado 21 43 34 48 / 0 0 10 10
Winfield-KWLD 22 45 37 51 / 0 0 10 10
Russell 17 40 27 41 / 0 0 0 10
Great Bend 18 42 28 42 / 0 0 0 10
Salina 17 42 30 42 / 0 0 0 10
McPherson 18 43 31 44 / 0 0 0 10
Coffeyville 23 44 37 54 / 0 0 20 30
Chanute 23 43 34 50 / 0 0 10 30
Iola 22 42 32 49 / 0 0 10 30
Parsons-KPPF 23 43 36 53 / 0 0 10 30
Area Forecast Discussion
National Weather Service Indianapolis IN
958 PM EST Fri Dec 9 2016
The Near Term section has been updated below.
Issued at 241 PM EST Fri Dec 9 2016
High pressure over the Missouri Valley will build in across central
Indiana tonight and Saturday and result in dry and cold weather.
However, that will be short lived as a southern Plains system is
expected to bring a variety of winter weather to central Indiana
Saturday night through Monday.
Two more quick moving systems next week will bring light snow to the
area and reinforce the cold air.
.NEAR TERM /Today and Saturday/...
Issued at 958 PM EST Fri Dec 9 2016
Aside from minor downward adjustments to min temps per latest LAMP
guidance, forecast in excellent shape. Previous discussion follows.
Issued at 602 PM EST Fri Dec 9 2016
Will add a flurries mention for the first few hours of the evening.
HRRR shows a shallow saturated dendritic growth zone...similar to
but much shallower and shorter lived than last night. Remainder of
forecast in good shape. Previous discussion follows.
Issued at 241 PM EST Fri Dec 9 2016
Models in good agreement that strong high pressure over the Missouri
Valley will build in across central Indiana tonight. Model rh time
sections, soundings, low level rh progs and satellite trends all
favor keeping plenty of stratocu around tonight. In addition, winds
will become light. This suggests temperatures will not drop too much
tonight, so will go a few degrees above MOS with lows in the upper
teens and lower 20s.
With high pressure starting off over top of central Indiana,
Saturday should be dry. As the high moves off to Appalachia Saturday
afternoon, should see the low clouds depart but AC increase as
isentropic lift commences. Could see a few breaks in the cloud
cover. Plus, low level flow will become southwest. This should allow
temperatures to warm back up to the upper 20s and lower 30s or near
a MOS blend.
.SHORT TERM /Saturday night through Monday/...
Issued at 241 PM EST Fri Dec 9 2016
Main challenge for the short term will be precipitation type,
amounts and timing as a low pressure system lifts northeast over the
region Sunday night.
Models in much agreement that a Rockies system will strengthen over
the Texas and Oklahoma panhandles by 12z Sunday and then lift
northeast to Lake Huron by 12z Monday. As it does it will drag a
cold front across central Indiana overnight Sunday night. This
system is expected to bring a variety of winter weather to central
Indiana starting Saturday night with far northern sections expecting
to see a few inches of snow and the south to see mainly rain. Warm
advection will start gearing up Saturday night ahead of the
aforementioned system and in the wake of departing high pressure.
The GFS was the one model that may be too quick to saturate the
column as seen in low condensation pressure deficits Saturday
evening. Prefer blend of the other short term models that are slower
to moisten things up. At any rate, can not rule out some light snow
north of Interstate 70 Saturday night. Small chance pops look good
By Sunday, isentropic lifts really gets going, and the atmosphere
quickly saturates down. 140 plus upper jet will move across southern
lower Michigan, enhancing the lift. Precipitation will become
widespread Sunday afternoon and night before the precipitation ends
Monday morning in the wake of the cold front.
Precipitation should start off as snow Saturday night and Sunday
morning and gradually transition to a mix of freezing rain, sleet
and rain from south to north. By 00z Monday, it should be rain over
all but extreme northern parts of the forecast area, where some snow
and sleet could mix in. Finally, the precipitation will exit
Randolph county Monday morning before ending.
Snow totals could reach 3 plus inches in the Kokomo and Delphi areas
by Monday morning and quickly drop off to an inch or less from
Indianapolis to the south. Total ice accumulation is expected to be
less than a tenth of an inch.
With models continuing their warming trends, not confident we will
see enough snow or ice to warrant a Winter Storm Watch at this
point. Watches from adjacent offices are also north of our border
.LONG TERM /Monday night through Friday/...
Issued at 214 PM EST Fri Dec 9 2016
The long term pattern looks somewhat active with mostly zonal flow
across the area. For Tuesday into Wednesday central Indiana is
pinched between building high pressure from the northwest and a
surface low moving northeast out of the Gulf. Latest ECMWF and GFS
keep an qpf out of the area until Wednesday and removed some pops
in the southwest from midday Tuesday through some of the overnight
considering that and collaboration. See some potential for a rain
snow mix in the south at onset, if any precip occurs Tuesday
evening. On Wednesday an upper wave will move through as well, and
see some chances for snow with this. Fairly dry as far as moisture
is concerned so pops are midrange at best. Temperatures will drop
pretty rapidly with northwesterly winds and cold Canadian air
spilling down of the back side of the large upper low moving east
across Ontario. Wind chills in the single digits Wednesday morning
and below zero Wednesday night, Thursday morning and possibly
.AVIATION /Discussion for the 10/00Z TAFs/...
Issued at 602 PM EST Fri Dec 9 2016
Mainly VFR through the period, although some brief MVFR ceilings
will be possible at times early in the period as ceilings are within
a few hundred feet of the borderline.
Winds will generally be less than 10kt through the period, remaining
northwesterly overnight, and then backing to southeasterly by the
end of the period.
No significant obstructions to visiblity are expected through the
Area Forecast Discussion
National Weather Service Louisville KY
925 PM EST Fri Dec 9 2016
Issued at 926 PM EST Fri Dec 9 2016
Made a few adjustments to sky cover given recent satellite trends.
Also, dropped MinT 1 degree north of I-64 and 1-3 degrees south of I-
64 given current T/Td and the fact that the center of the incoming
Arctic high will be directly overhead at 12Z.
Issued at 548 PM EST Fri Dec 9 2016
Reflectivities, while still weak, have increased quite a bit north
of I-64 so have gone ahead and thrown isolated flurries into the
forecast for southern Indiana east of Patoka Lake and central
Kentucky north of 64. Also increased cloud cover to 100% where it is
.Short Term (Now through Saturday Night)...
Issued at 239 PM EST Fri Dec 9 2016
As of mid afternoon, high pressure over Arkansas and low pressure
over the Great Lakes was continuing northwesterly flow over the
lower Ohio Valley. Upstream moisture and cold temperatures aloft in
the cyclonic flow resulted in an extensive strato-cu deck across
southern Indiana and north-central Kentucky. A recent RAP sounding
showed these clouds remained in the snow growth region around -12C,
and regional radar and surface observations confirm light snow
flurries across parts of the area. It`s been a cold day with
readings in the mid/upper 20s under the clouds while closer to the
TN border temperatures have risen to around the freezing mark.
The main focus in the short term is cloud trends and temperatures.
Latest visible satellite shows the strato-cu deck extending upstream
through Illinois and Indiana. Plan on a mostly cloudy to cloudy
night for far northern Kentucky and southern Indiana, and this is
where there might be a few flurries around through the night as
well. Otherwise, lows tonight will fall into the teens to low 20s.
The aforementioned high pressure moves nearly overhead during the
day tomorrow and should provide the area with more sunshine and
slightly warmer, but still below normal, high temperatures. Readings
are expected to top out in the low 30s across southern Indiana to
mid/upper 30s across central Kentucky. The high quickly moves east
and southerly return flow sets up Sunday night. The tighter pressure
gradient should keep the boundary layer mixed enough to hold lows in
the mid/upper 20s.
.Long Term (Sunday through Friday)...
Issued at 241 PM EST Fri Dec 9 2016
A few items of interest in the long term with the focus on the storm
system for Sunday and Monday, then another surge of Arctic air for
Low pressure is forecast to move from the central Plains toward the
Upper Midwest Sunday and Sunday night. Overall, the 09.12z models
continued the trend of slowing down the frontal passage Sunday. As a
result, collaborated with PAH/OHX/IND to reduce chances early Sunday
morning, but still bring in higher chances during the afternoon and
evening, west to east. This further reduces the threat of a wintry
mix locally. Ahead of it, a push of Gulf moisture will bring higher
PWATs between 0.75 and 1.0 inches and combined with stronger forcing
for ascent, rain showers should break out across the area,
especially Sunday evening and night. Rain will taper off and move
east of the area Monday morning. Overall, total rainfall amounts
between 0.5 and 0.75 inches are forecast.
Temps will be warmer for the first part of the week. Highs look to
range through the 40s Sunday and 40s/lower 50s Monday. Temps
shouldn`t drop off much Sunday night with lows in the mid 30s to
Forecast confidence drops off mid-week as the global deterministic
and ensemble models aren`t exactly painting the same picture
regarding the synoptic pattern. It does look like a stronger upper
level trough will dive toward the region mid-week which will bring
another round of colder temperatures (perhaps colder than the
current cold snap) but whether any shortwave troughs or surface
systems interact with this cold air remains in question. Sided with
a model consensus with just slight chances of rain/snow mix Tuesday
through Wednesday night. This is a compromise between the dry, cold
ECMWF solution versus the wetter, still cold, GFS and GEM.
Temperatures will trend downward mid-week onward with highs Thursday
and Friday potentially staying in the 20s or low 30s, and morning
lows in the teens.
.Aviation (00Z TAF Update)...
Issued at 626 PM EST Fri Dec 9 2016
Relatively quiet weather, but still not an easy forecast as we deal
with a stubborn stratocu deck over SDF and LEX. Looking at satellite
and model data, will give a best stab at when those airports will
lose their ceilings this evening. Base heights will be right around
3,000 feet, so the airports will be either VFR or MVFR by just a
couple hundred feet at any given time. Interestingly, the RAP, which
did an admirable job forecasting this stratus at this time
yesterday, shows possible rebuilding of the low clouds late tonight.
Again, these would be right around the VFR/MVFR boundary. Will go
ahead and include a TEMPO for possible ceilings during the pre-dawn
hours, but this will need to be re-evaluated as the evening
progresses to see if the signal remains.
A weak upper wave crossing the Wabash Valley at this writing is
helping to spark a few flurries from the clouds, but those will be
of no consequence to aviation.
Saturday looks nice with just some mid/high clouds and very light
winds as high pressure moves right through Kentucky.
For frequently asked questions about the Area Forecast Discussion
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
752 PM EST Fri Dec 9 2016
01Z water vapor and H4 RAP analysis continue to show an
unamplified upper level pattern over the CONUS this evening.
Northern stream flow runs in a mostly zonal configuration across
the mid-section of the country...while the subtropical jet cuts
across the Gulf of Mexico and over the southeastern States/FL
peninsula before exiting into the Atlantic. High level clouds
over our heads this evening are being forced by RRQ dynamics/lift
within the exit region of the the subtropical jet core. As this
core/jetstreak moves away later tonight/Saturday morning...so
should the upper level moisture/lift for the clouds. Other than
perhaps are far southern zones down toward Fort Myers...this
should allow for quite a bit of sunshine to develop Saturday
morning. This will be nice...since it will be rather chilly to
start the day. Later in the day...winds shift more to the east in
the lower levels will begin to deliver some added moisture below
850mb...and this will lead to a sct-bkn fair weather cumulus/stratocu
fields in the afternoon. Most fair weather cu will be south of the
I-4 corridor where the influx of Atlantic moisture will be
Otherwise...the forecast is dry for the remainder of tonight and
Saturday for all zones. Low temperatures by dawn range from the
lower 30s over inland Levy county to the middle 40s along the I-4
corridor...and then lower 50s down toward Fort Myers. While a few
locations in Levy county may approach freezing for an hour or
2...it is unlikely any spots will fall below 32. Also...a steady
4-6mph wind from the north should generally prevent the formation
of frost for all but the most sheltered locations. Anywhere from
Crystal River south should have no frost/freeze concerns tonight.
After the cool start to the morning...temperatures should rebound
nicely by the afternoon Saturday. Will see temps into the
lower/mid 60s over Levy County...to the upper 60s/lower 70s along
I-4...and lower to middle 70s headed southward to Fort Myers.
A steady warming trend continues in both overnight lows and
daytime highs during the second half of the weekend and early
portion of next week.
Have a great Friday night and a safe/fun weekend everyone! Stay
.AVIATION (10/00Z through 11/00Z)...
VFR conditions will prevail at all terminals through the TAF
period. High level clouds will be thinning out and retreating
later tonight into Saturday morning...followed by a sct-bkn
cumulus field developing during Saturday afternoon. Moderate winds
from the northeast through the period.
Elevated winds and seas over the eastern Gulf waters have led to a
small craft advisory into Saturday morning. Winds and seas will
subside below advisory levels during Saturday and through the
remainder of the weekend as high pressure shifts east of the
region into the Atlantic. However...periods of near cautionary
level easterly winds will remain in the forecast through much of
.Prev Discussion... /issued 228 PM EST Fri Dec 9 2016/
SHORT TERM (Tonight through Saturday)...
High pressure to continue to build into area with overnight lows
near normal in Fort Myers and 5 to 10 degrees colder than normal
elsewhere. Temperatures around Williston in Levy County could
reach 32 degrees by morning but it is not expected to be
widespread. Wind chills in this area could reach 29 degrees but
this is still above the wind chill criteria of 25 degrees.
The moisture returns quickly this weekend with dew point
temperatures warming into the 50s Saturday and 58 to 65 Sunday.
High temperatures Saturday to be only 1 to 2 degrees below normal.
LONG TERM (Saturday Night through Friday)...
Fast zonal flow will over spread the CONUS to kick off the medium
range period, setting up a highly progressive weather pattern for
several days into next week. Surface high pressure will reside over
the eastern half of the CONUS with strong surface cyclogenesis over
the Central and Southern Plains regions. This will favor moist
southeasterly flow across the Gulf Coast for the first half of the
From Saturday Night through early next week, we will experience a
rather fast warmup as moisture-rich southerly flow persists across
the region. Highs will reach the mid to upper 70s and 80s each day
with lows only falling into the lower 60s most areas. A weak front
will approach the region Monday, but looks to stall to the north as
much of the upper level energy driving it southward departs to the
north. These scenarios often favor fog and low clouds, and
especially marine fog, assuming the shelf waters have cooled
substantially. Thus, have opted to add a mention of patchy marine
fog beginning Monday night and continuing through at least Tuesday
Much uncertainty exists as we head into the middle of next
week. Several shortwave impulses look to move through the fast zonal
flow pattern, producing a highly unpredictable setup. At this time,
it does appear a stronger front will near the Florida peninsula
during the latter half of next week, but longer range solutions
differ wildly on the strength of the front, any associated rainfall,
and the depth and intensity of trailing cold air. For now, will lean
toward a slow frontal progression late Wednesday into Thursday with
only slightly cooler air moving in. However, the ultimate result
will likely be vastly different from the existing forecast.
No fire weather and no fog concerns in the forecast through the
.Preliminary Point Temps/PoPs...
TPA 48 71 58 78 / 0 0 0 10
FMY 54 74 61 81 / 10 0 10 20
GIF 48 70 56 78 / 0 0 0 10
SRQ 51 72 59 80 / 0 0 0 10
BKV 42 69 52 78 / 0 0 0 10
SPG 51 70 60 76 / 0 0 0 10
Gulf waters...Small Craft Advisory until 7 AM EST Saturday
for Coastal waters from Bonita Beach to Englewood FL
out 20 NM-Coastal waters from Englewood to Tarpon
Springs FL out 20 NM-Coastal waters from Tarpon Springs
to Suwannee River FL out 20 NM-Waters from Tarpon
Springs to Suwannee River FL out 20 to 60 NM.
Small Craft Advisory until 1 PM EST Saturday for Waters
from Bonita Beach to Englewood FL out 20 to 60 NM-
Waters from Englewood to Tarpon Springs FL out 20 to