Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/17/19
Area Forecast Discussion
National Weather Service Binghamton NY
1058 PM EST Mon Dec 16 2019
.SYNOPSIS...
A low pressure system will bring snow and a wintry mix to the
area overnight into Tuesday as it slides through the Mid-
Atlantic region. Temperatures turn much colder with numerous
snow showers and possible snow squalls on Wednesday as an arctic
cold front moves through.
&&
.NEAR TERM /THROUGH TUESDAY/...
This late evening update includes the 00z NAM, HRRR and RAP
model into the forecast along with any trends late this
evening. A snow and sleet mixture is spreading northward into
northeastern PA as we head into the early morning hours. Some
sleet has been reported in Luzerne county within the last hour.
Modeling has trended away from a burst of moderate/ heavy
snowfall driven by FGEN forcing in NE PA overnight, With only
lighter precipitation, the warm-up is occurring faster in the
mid- levels. So trends are toward a few hours of light snow
changing to freezing rain and sleet for most of NE PA. Areas in
the Wyoming valley should rise above freezing Tuesday and
change to rain. The net result here is a decrease in expected
to just a couple of inches in NE PA. Still the light snow along
with an interval of freezing rain and sleet will lead to
difficult travel.
A changeover to sleet and freezing rain occurs Tuesday morning
with icing amounts around a tenth of an inch in the higher
elevations of the Poconos region and lesser amounts elsewhere.
How far north the mixing line will make it is still uncertain,
but thinking we will see some sleet and freezing rain to at
least the Southern Tier of NY. the late evening update nudged
this a bit further north based on the latest HRRR/NAM model
runs. Also, the latest model data shows a secondary burst of
moderate to perhaps heavy precipitation trending stronger
Tuesday afternoon due to FGEN forcing. Where this is snow, snow
totals have been increased a bit given the trends.
Temperatures should be in the 20`s into the the low 30`s
throughout the event with some mid 30`s in the Wyoming Valley.
Summary...
NE PA: Period of snow changing to sleet and freezing rain by
sunrise. Lowered snowfall totals based on observations and model
trends. Warming enough for rain Tuesday in the Wyoming valley.
Southern Tier NY: Snow developing overnight. Mixing with sleet
and freezing rain Tuesday. Increased forcing leading to narrow
band of heavier snow with local 6 inch totals by Tuesday
morning. Less snow where mixing occurs across the northern Tier
of PA.
Finger lakes/ NY Thruway: Few changes. Several inches of snow
mainly Tuesday.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
With the plenty of instability Wednesday, some thunder is
possible with the afternoon snow showers.
Light snow showers in the area Tuesday night in the wake of the
storm with the northwest flow. Main event in the period begins
on Wednesday as an arctic cold front plunges into the area.
Considerable, deep instability, for winter, accompanies the
front with a sharp surface convergence and adiabatic lapse rate
will lead to snow squalls along the front. Current timing pushes
the front through around midday with strong cold advection
firing additional lake enhanced squalls behind the front. With a
quick inch of snow and very low visibility and strong wind
gusts, snow squall warnings on Wednesday a definite possibility.
Lake effect continues into Thursday with a NW flow event and
near Advisory snow amounts likely over the northern zones into
the Finger Lakes. Despite the extreme instability, limiting
factors are evident including extremely dry air and a good amount
of shear that may limit the intensity of the band(s). Also,
subsidence inversion drops down to near 900mb by Thursday
morning.
With the cold, temperatures will drop into the single numbers
across the area, with some lows below zero in Oneida county.
Adding in the winds, wind chills will be approaching Advisory
criteria Thursday morning.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Westerly flow across the Great Lakes will cause light lake
effect snow showers over northern and western sections of the
forecast area Thursday before high pressure builds in Thursday
night. Temperatures will drop into the single digits Thursday
night with below zero readings to the far north.
Chilly but quiet weather is forecast for Friday as temperatures
rise into the 20s.
A weak wave could produce isolated snow showers on Saturday and
Sunday. Temperatures will rebound into the middle 30s on
Saturday and the upper 30s on Sunday.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Conditions remain VFR at all terminals this evening. This will
be short-lived, as lower ceilings and precipitation begin to
move in from south to north, with KAVP the first terminal to
likely see restrictions (likely after 02Z). Expecting all
terminals to quickly lower to IFR later tonight as precipitation
overspreads the area. While the majority of the precipitation
across the area will be in the form of snow, snow is expected to
transition to a wintry mix, especially at KAVP, but also
briefly for KELM and possibly KBGM. Conditions gradually improve
somewhat by the end of the TAF period as the storm system
departs.
Winds will be light and variable this evening, before becoming
easterly, and eventually northerly by Tuesday afternoon at less
than 10 knots. Winds shift to a more northwesterly direction as
the storm departs late in the period.
Outlook...
Tuesday night...occasional MVFR in snow showers.
Wednesday and Wednesday night...MVFR/IFR restrictions with snow
showers and squalls in CNY. MVFR AVP.
Thursday...VFR. Possible restrictions in CNY due to lingering
lake effect snow showers.
Thursday night through Saturday...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 4 PM EST Tuesday for PAZ038>040-
043-044-047-048-072.
NY...Winter Weather Advisory until 4 PM EST Tuesday for NYZ022-024-
055>057-062.
Winter Weather Advisory until 6 PM EST Tuesday for NYZ015>018-
023-025-036-037-044>046.
&&
$$
SYNOPSIS...MPK
NEAR TERM...MPK/MWG
SHORT TERM...DGM/MWG
LONG TERM...DGM/DJP
AVIATION...BJG/DGM
Area Forecast Discussion
National Weather Service Buffalo NY
1030 PM EST Mon Dec 16 2019
.SYNOPSIS...
Thickening high clouds will give way to light snow later tonight as
area of low pressure moves by just to the south of New York. Snow
will continue into Tuesday, with the greatest amounts across the
Southern Tier and Finger Lakes region, though even some minor
accumulations are expected over the Niagara Frontier, including at
Buffalo and Rochester. Lake effect snow will develop Tuesday night
and Wednesday, as a much colder airmass arrives for the middle of
the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
Recent runs of the RAP and HRRR and now the 00z NAM have trended
toward more QPF farther north into the Niagara Frontier, including
at Buffalo and Rochester. Nudged total snow amounts up around 1
inch, so now looking at 2-3, maybe isold 4 inch amounts in
these areas. Still will keep the advisory where it was in place
originally, but even in those areas have bumped up totals more
into the 4-6 inch range, with isold 7 inch amounts not out of
the question. This all occurs as shortwave trough over central
CONUS causing the snow from eastern MO into central IN this
evening shifts east-northeast and interacts with inverted sfc
trough extending to the north of primary area of low pressure
vcnty of Tennessee that continues to cause all sorts of severe
weather issues this evening. As it has looked for a while, the
whole shield of snow will be enhanced due to upper divergence
from right entrance region of strong upper jet and low-mid level
frontogenesis (especially H85-H7 layer).
Think main surge of snow occurs 10z-17z/5 AM through 12 PM. So the
commute on through the morning will be impacted over much of the
area. Right now SLRs are expected to be in the 10-15:1 range and
there will be little wind, so it will just be the snow that impacts
travel instead of snow and blowing snow. Now there have been a few
obs well upstream to south of main shield of snow over IL/IN that
show unknown precip or even freezing drizzle. This lines up well
with where moisture strips out at temps colder than -10c (so losing
the ice nucleation aloft). This drying aloft still on track to try
to push as far north as NY/PA border late tonight and into mid
morning Tue, so kept the mention of at least a chance of freezing
drizzle for those areas.
As low pressure tracks across New Jersey and off the southern New
England coast by Tuesday afternoon, widespread snow will gradually
diminish and it may transition to more of a showery regime mid to
late afternoon as axis of shortwave trough/colder air aloft crosses.
With enough moisture, a few of those snow showers could briefly drop
vsby locally. Highs on Tuesday will range from the upper 20s to low
30s across the higher elevations to the low to mid 30s across the
Lake Plains.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
The widespread synoptic snow from Tuesday will be exiting the
eastern Lake Ontario region early Tuesday evening. There will be at
least some limited lake effect snow developing in the wake of this
system as temperatures aloft become marginally cold enough.
Off Lake Erie...
Expect lake enhanced upslope snow showers to continue through the
first half of the night across the Chautauqua Ridge and Boston Hills
on northwest flow. Overnight, boundary layer flow will begin to back
to the west and southwest ahead of the next system. This will allow
the upslope snow showers to re-organize into a more shore parallel
band along the Chautauqua County shoreline after midnight. This band
will then move northward towards Buffalo by the pre-dawn hours of
Wednesday. The ever changing mode and location of the lake snow
should keep accumulations relatively light, with 2-3 inches possible
where the snow persists.
Off Lake Ontario...
Lake effect snow will organize in the evening over Wayne County in
northwest flow. Boundary layer flow will then back to westerly
overnight. This will push the lake effect snow eastward along the
south shore of the lake from Wayne to Oswego counties. The steady
movement of this band should also limit accumulations to the 2-3
inch range.
A very interesting setup then evolves for Wednesday. A very strong
and sharp mid level trough will move southeast across Ontario,
reaching New England Wednesday night. Despite the closed off 500MB
low, this system will remain very progressive. An associated cold
front will cross the eastern Great Lakes Wednesday morning. The cold
front will combine with pre-existing lake effect snow bands to
produce a brief burst of heavy lake effect snow east of the lakes,
and raise the possibility of fast moving snow squalls even inland
from the immediate lake effect areas.
Off Lake Erie...
Expect the band of lake snow to briefly make it up to about Buffalo
and Batavia. Note, this idea is north of most of the high resolution
model guidance, which often has a notable southward bias in these
situations. This will occur right during the morning commute. The
cold front will then capture the lake band and drive it rapidly
south and east through the western Southern Tier from mid morning
through midday. The rapid band movement during this time should keep
accumulations in the advisory range, even if the snow becomes heavy.
Expect accumulations of 3-5 inches on average for Wednesday where
the bands persist the longest.
Late Wednesday and Wednesday night boundary layer flow continues to
veer to the northwest. This will carry the lake effect snow into the
western Southern Tier, primarily Chautauqua and western Cattaraugus
counties. Mesoscale model guidance suggests an upstream connection
to Lake Huron will develop and enhance the snow in this area despite
the short fetch across Lake Erie. The upstream connection may
support an additional 3-5 inches in persistent bands. The lake
effect snow will begin to weaken later Wednesday night, then end
Thursday morning as high pressure builds over Lake Erie.
Off Lake Ontario...
Lake effect snow will re-organize to the northeast of the lake by
mid morning with the approach of the cold front. A combination lake
effect snow band and frontal squall will then move east across the
eastern Lake Ontario region late morning and early afternoon,
dropping a quick 2-4 inches, with 3-5 inches possible on the Tug
Hill with added orographic enhancement. By mid to late afternoon
boundary layer flow will become WNW, allowing lake effect snow to
focus southeast of the lake from Wayne to southern Oswego counties.
Wednesday night boundary layer flow will continue to veer to the
northwest. This will allow the lake effect snow band to move onshore
and back westward along the south shore, from Wayne County westward
to at least Orleans County, including the Rochester Metro area.
Mesoscale model guidance suggests an upstream connection to Georgian
Bay will develop during this time, enhancing the Lake Ontario snow.
This will bring a good chance of 3-5 inches across much of the south
shore of the lake from Orleans to Wayne counties, including the
Rochester area. There could be locally more if the band and upstream
connection stall for several hours in one location, but right now it
looks like this band will keep moving.
Northwest flow will maintain a spray of multiple bands southeast of
Lake Ontario through Thursday, but additional accumulations should
be light during this time as inversion heights lower, synoptic scale
moisture continues to decrease, and the Georgian Bay connection is
lost.
Wednesday and Wednesday night winds will become quite strong, with
gusts of 35-40 mph common on the lake plains and 30-35 mph farther
inland. This will produce areas of blowing and drifting snow. It
will turn very cold Wednesday night, some of the coldest air we have
seen this early winter season. Lows will drop into the single digits
away from the immediate lakeshores, and below zero east of Lake
Ontario. Wind chills will drop below zero, and may approach wind
chill advisory criteria for a brief time late Wednesday night and
Thursday morning across the eastern Lake Ontario region and the
higher terrain of the Southern Tier.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
An unusually quiet period of weather looks to set up late this week
through early next week as the pattern becomes more zonal across the
US with an expansive ridge dominating the mid section of the nation.
Our region will remain on the edge of the above normal temperatures
that will build across much of the US. The upper level pattern
leaves the door open for the potential of weak fronts moving south
out of Canada, which may prevent the well above normal temperatures
from reaching the eastern Great Lakes.
Looking at the details, any lingering light lake effect snow showers
southeast of Lake Ontario will end Thursday night. High pressure
will then dominate the eastern US Friday through the weekend. Sunday
night and Monday the Canadian GEM, and to some extent the GFS, bring
a trough through Ontario and Quebec, with a weak front possibly
moving south into our region. The ECMWF keeps this system much
farther north and west. Given the weak signal, kept the forecast dry
through Monday for now. Despite the lack of systems, the warming
temperatures aloft at this time of year will likely support a
steepening low level inversion, so we may end up with low stratus
clouds much of the time.
Temperatures aloft will warm through the period, although surface
temperatures may lag behind with the expectation of a steepening
inversion. Went with a gradual warming trend through the weekend to
slightly above normal.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
VFR conditions will continue through early overnight with only JHW
seeing some MVFR cigs at times.
Weak low pressure will track south of the area and bring widespread
steady snow to New York State late tonight and Tuesday. Prevailing
cigs will start to lower to MVFR across the Southern Tier by 06z,
then areas south of the NYS Thruway will deteriorate to IFR in light
snow by 12z Tuesday. While periods of heavier snow is possible,
light snow is expected through this event for the TAF sites. IFR
vsbys are likely across western NY Tuesday. Steady snow doesn`t
reach KART until Tuesday morning. Expect improvements from west to
east late Tuesday afternoon. A brief period of VFR conditions will
then occur on Tuesday evening before localized IFR develops late
Tuesday night east of the lakes as lake effect snow develops.
Outlook...
Wednesday...IFR in lake effect snow east of the lakes, with VFR
elsewhere.
Thursday...IFR in lake effect snow showers southeast of the
lakes, VFR elsewhere.
Friday and Saturday...VFR.
&&
.MARINE...
Light winds and waves will be replaced by another period of stronger
winds later Tuesday night through Wednesday as a strong cold front
crosses the region. Expect widespread small craft advisory
conditions by this time.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 4 PM EST Tuesday for NYZ012>014-
019>021-085.
MARINE...Small Craft Advisory from 7 AM Wednesday to 1 AM EST Thursday
for LEZ020.
Small Craft Advisory from 10 PM Tuesday to 7 AM EST
Thursday for LEZ040-041.
Small Craft Advisory from 7 AM Wednesday to 1 AM EST
Thursday for LOZ030.
Small Craft Advisory from 4 AM Wednesday to 1 PM EST
Thursday for LOZ042>045.
&&
$$
SYNOPSIS...EAJ/HSK/JLA
NEAR TERM...HSK/JLA
SHORT TERM...Hitchcock
LONG TERM...Hitchcock
AVIATION...HSK/JLA
MARINE...HSK/JLA/Thomas
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
856 PM MST Mon Dec 16 2019
.UPDATE...
Issued at 853 PM MST Mon Dec 16 2019
Mid-evening update included lowering temperatures a few degrees
through the early morning most locations as winds have dropped off
in the lower elevations a bit (for now) and winds have partially
decoupled allowing for a more rapid fall of readings. We still
expect to see the winds start to pick up after midnight and will
leave the High Wind Warning as is for now. Wind chill readings for
the western areas will be around 20 below zero for a period of
time in the early morning before seeing mixing increase a bit and
temps warm (especially where downsloping will have an effect). No
other changes to the forecast at this time. /JG
&&
.SHORT TERM...(Tonight - Tuesday)
Issued at 249 PM MST Mon Dec 16 2019
A challenging wind forecast across southeast Wyoming over the next
12-24 hours. Low-level gradients are expected to increase markedly
during the evening/overnight, with the GFS showing 850/700 mb CAG-
CPR gradients climbing to 65-75 meters between 9z and 15z Tue. The
considerably less aggressive NAM shows gradients peaking around 55
meters during the same time frame, still sufficient for high winds
at ARL. This may be a fairly quick-hitting high wind episode, with
the main driver being a fast moving disturbance diving from north-
west to southeast across the state tonight through Tuesday AM. The
subsidence in the wake of this feature could be a major player for
60+ MPH wind gusts.
Flow aloft appears to be fairly modest over the majority of our SE
WY wind corridors, but models agree on a narrow ribbon of 50+ knot
flow in the vicinity of Bordeaux at 800 millibars at some point on
Tuesday AM. A 3-5 mb surface pressure gradient oriented from west-
east along the Laramie Range appears quite favorable for Bordeaux,
and despite largely northwesterly flow aloft, significant WAA will
be present near mountain tops leading to trapping of stronger flow
in the low levels due to a significant inversion. X-sections along
the central Laramie Range, coupled w/ recent HRRR projections & in
house probabilistic guidance strongly suggests 60-70 MPH gusts for
the BRX area. The I-80 Summit is a bit tricker as that area is not
impacted by gap mechanisms, but significant subsidence & downslope
enhancements could bring winds near warning criteria. Arlington is
probably the least impressive zone based strictly on 700 to 800 mb
flow, but it is hard to ignore those gradients and we have already
seen gusts 45-50 MPH with gradients expected to double in the next
few hours.
That said, High Wind Watches were upgraded to Warnings for ARL and
BRX from 11 PM this evening until 5 PM MST Tue. We included the I-
80 Summit based on the above reasoning. It is quite possible for a
few gusts to spill into the S. Laramie Range foothills, but models
show subsidence dropping off considerably east of Buford. The next
couple of shifts will need to monitor trends closely.
.LONG TERM...(Tuesday night - Monday)
Issued at 302 AM MST Mon Dec 16 2019
Winds will continue to be strong and gusty through Tuesday night
as temperatures cool down again. The gustier winds may introduce
some lower wind chills to the west. However, current guidance
doesn`t suggest the need for any wind chill products at this
time. Skies should again remain clear overnight Tuesday and
through Wednesday. Surface pressure gradients will weaken slightly
Wednesday morning but should start to increase again Wednesday
evening.
By Thursday morning, partly cloudy skies are expected as a fast
moving upper level storm system moves in from the south and west.
Winds aloft will be on the increase, and gusty winds are again
expected. This appears to be the more promising high wind event
with some potential for gusty winds to spill off the mountain and
on to the plains Thursday afternoon. With dry downslope flow,
temperatures will be on the rise and dry weather is expected.
The rest of the week and through the weekend looks mostly dry as a
zonal jet aloft and westerly winds are expected to keep things
quiet and warmer. There are some indications of a more active
winter pattern develop late in the day 8 to 10 range but model
difference preclude any meaningful forecast at this point.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 430 PM MST Mon Dec 16 2019
VFR conditions are expected through the forecast period with gusty
westerly winds picking up tonight across SE WY terminals. Gusts of
20-25 kts are possible near KCYS and KRWL overnight tonight and
into Tuesday. NE Panhandle terminals will begin to see winds
increase after 16z Tuesday.
&&
.FIRE WEATHER...
Issued at 302 AM MST Mon Dec 16 2019
Fire weather concerns are expected to be low due to snow cover and
cold temperatures. Gusty winds will likely develop by mid week
but fuel curing is not expected due to snow cover.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 5 PM MST Tuesday for WYZ106-110-116.
NE...None.
&&
$$
UPDATE...JG
SHORT TERM...CLH
LONG TERM...AL
AVIATION...MB
FIRE WEATHER...AL
Area Forecast Discussion
National Weather Service Green Bay WI
602 PM CST Mon Dec 16 2019
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 231 PM CST Mon Dec 16 2019
The latest RAP analysis and satellite/radar imagery show a high
pressure ridge axis extending east across southern Wisconsin. Low
clouds are holding steady across much of northeast Wisconsin early
this afternoon, though partial clearing continues slowly over
northwest and far northern WI. Scattered flurries have persisted
across far north-central WI despite a few holes in the cloud cover
at times. Looking upstream, mostly clear skies prevail across much
of central and northern Minnesota. but the next area of cloud
cover is moving southeast over the Dakotas. Forecast concerns
include sky trends and snow shower chances on Tuesday.
Tonight...The surface ridge axis will extend across southwest to
northeast Wisconsin. Cloud cover remains difficult to forecast,
but counting on a slow clearing trend to take place from northwest
to southeast this evening as models continue to indicate a drying
of the low levels. Did slow down the clearing trend as clouds
will be tough to dissipate beneath the inversion, and lack of any
diurnal heating. After the brief period of clearing, clouds are
expected to increase again from the northwest overnight. It
doesn`t appear that there will be enough saturation depth for
light snow, especially since winds are too westerly for a lake
effect component off Lake Superior. Due to the cloud cover and
light winds of 5 to 10 mph, remained conservative for temps, which
should range from the low single digits above zero to the middle
teens near Lake Michigan.
Tuesday...A shortwave digging southeast across the northern Great
Lakes will push a reinforcing arctic front across northern WI.
After mainly dry conditions in the morning under partly to mostly
cloudy skies, arrival of stronger forcing and deeper saturation
should lead to scattered light snow showers in the afternoon along
the front. Not expecting much in the way of accumulations, perhaps
a tenth or two over north-central WI. Temps will be slightly
cooler than todays readings, and range from the middle teens to
low 20s.
.LONG TERM...Tuesday Night Through Monday
Issued at 231 PM CST Mon Dec 16 2019
Quiet weather is expected through much of the extended forecast. The
main concerns will be the well below normal temperatures through
Wednesday along with some light lake effect snow near Lake Superior.
In fact, wind chill values may approach advisory criteria for
central and north-central portions of the area Tuesday night into
Wednesday morning.
Tuesday night and Wednesday: A fairly strong shortwave and arctic
cold front are expected to slide through the area for this time
period. Along the cold front and shortwave axis, light snow showers
or flurries will likely develop and slide from northwest to
southeast across the area. The best chance will be Tuesday night as
upper jet supports large scale forcing. Clearing skies are expected
behind these features. The main limiting factor for any appreciable
precipitation will be the lack of moisture in the lower levels of
the atmosphere. Still enough moisture to give a few snow showers or
scattered flurries. The better chance of seeing any light
accumulation, will be across north-central Wisconsin, where lake
effect/enhanced snow is expected to develop. Winds will be from the
favored north to northwest direction through Wednesday morning,
before quickly shifting to the west and southwest by the afternoon
hours. This would quickly end any ongoing lake effect snow. The very
cold airmass in place will likely limit snow to liquid ratios as the
DGZ is very close to the ground. Only expecting an inch of two of
snow with visibility reduction being the main impact due to small
flake size. Otherwise, temperatures are expected to be well below
normal with lows dropping into the teens below zero across central
WI with much of the rest of the area in the single digits above
zero. Light winds/CAA to the east of the approaching high, may lead
to wind chill values dropping into the -15 to -25 degree range
Tuesday night into Wednesday morning across central and north-
central WI. Temperatures may be kept a bit warmer where lake clouds
linger the longest. High temperatures Wednesday are expected to be
in the single digits to mid teens above zero, coldest central and
north-central.
The rest of the extended looks to be fairly quiet with only a few
subtle/moisture starved features passing through the area. Upper-
level ridging will build across much of the area into the upcoming
weekend. This will result in steadily warming temperatures, with
many places warming above normal by the end of the work week into
the weekend. A weak system will likely brush through the area Friday
into Friday night, allowing for increased clouds and perhaps a
flurry or sprinkle, but generally looks dry for that time period.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 558 PM CST Mon Dec 16 2019
Cloud trends again present a major aviation forecast issue. A low
deck with MVFR bases was across most of the area, but the edges
were close to the northwest and southeast parts of the area. Opted
to hold onto the current bases for a while this evening, then
trended toward the normally reliable LAV and GLAMP guidance later
tonight into tomorrow. Some low-end LLWS is again possible across
mainly the north and west late tonight.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Cooley
AVIATION.......Skowronski
Updated for 00Z Aviation Forecast Discussion below.
DISCUSSION...
Tonight...main story will be continued severe weather threat over
our southern and southeastern counties. CAPE values have reached
500-1000 J/kg over northern/northeastern MS. Vertical wind shear
remains favorable for storm organization and rotation. Line of
storms is becoming organized over NW MS, with some smaller more
discrete cells ahead of line. Most favored area for severe will
persist ahead /east-southeast/ of the line.
Meanwhile, over our far northern counties, may see a brief
mixture of frozen precip as precipitation clears out. Will include
mention of rain or light snow overnight, with no accumulation
expected.
Tuesday through Friday...mainly dry and cool conditions expected as
surface high pressure builds in. Surface ridge should remain over
the area into early Thursday with northerly winds persisting.
Falling pressures to the west in advance of upstream system will
generate return southerly flow late Thursday into Friday night.
Saturday through Monday...next system will swing across the region
on Saturday. GFS and ECMWF both keep system south of our area, with
the GFS a little stronger with the system. Will go with low POPs and
low QPF over our southern counties. Upper level ridging builds over
the area Sunday-Monday, which will bring southerly winds and mild
temperatures into the area for the beginning of next week.
GW
&&
.AVIATION...
00Z TAFs
Back edge of -DZ/-RA moving through the MEM TRACON at 00Z.
Widespread IFR ceilings were noted upstream over northeast AR and
southern/central MO.
NAM and RAP soundings depict lifting ceilings to MVFR with
frontal inversion depth overnight, but MOS-based guidance such as
the LAV and MET guidance maintains IFR. Give the lack of frontal
depth increase in upstream ceiling observations, have maintained
the status quo for most of the overnight.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
637 PM EST Mon Dec 16 2019
.SHORT TERM...(This evening through Tuesday)
Issued at 421 PM EST MON DEC 16 2019
Water vapor imagery and RAP analysis show a weak shortwave swinging
across northern Ontario and the Upper Lakes. Upstream, a stronger
shortwave is dropping se across northern Saskatchewan. Behind the
associated arctic cold front, it`s bitter cold with early aftn temps
across northern Manitoba/northern Saskatchewan in the -20s F. Closer
to home, associated with the weak shortwave moving across the Upper
Lakes, a sfc trof has settled over Lake Superior. This trof brought
a burst of mdt/hvy snow to the Keweenaw earlier today. The trof is
now weakening and becoming more w-e oriented across southern
portions of Lake Superior. KMQT radar shows a less organized band of
heavier shsn along the trof over s central Lake Superior, and vis
imagery indicates this band extends w across the Keweenaw in the
vcnty of KCMX.
Weakening sfc trof over southern Lake Superior may slip a little far
s over eastern portions of the lake, resulting in heavier shsn
brushing the remote shoreline e of Grand Marais this evening.
Otherwise, LES will continue across the Keweenaw thru the evening
with a tendency for the shsn to lift n as winds back slightly ahead
of approaching shortwave. Localized accumulations of an inch or two
will be possible thru the evening. Ongoing flurries elsewhere will
dissipate over the next several hrs as drier air/clearing per
satellite imagery progresses eastward. Arctic cold front associated
with the Manitoba shortwave will move out across western Lake
Superior late tonight. As it does so, a band of mdt/hvy snow will
develop along it, sweeping onshore over the Keweenaw probably in the
10-13z time frame. A quick inch or two of snowfall will be possible.
This cold front will continue se across the area Tue morning into
the early aftn, accompanied by a brief period of mdt/hvy shsn,
especially e of Marquette. After the front passes, incoming dry
arctic air mass combined with some directional wind shear will work
to keep developing nw-se oriented LES bands on the light side.
Additional snow accumulations after passage of the snow band along
the cold front should not be more than 1 to perhaps 2 inches thru
the aftn hrs.
As for temps, expect clouds to scatter out at times to allow temps
to fall into the single digits above zero in the interior. Favored
the colder bias corrected CMC over interior e where temps may fall
to around -5F at the traditional cold spots due to expected less
cloud cover. Highs on Tue, generally mid teens to lower 20s, will be
reached prior to fropa. Temps will slowly fall after fropa with
readings generally down into the upper single digits over the nw
half by 00z Wed.
.LONG TERM...(Tuesday night through Monday)
Issued at 421 PM EST MON DEC 16 2019
Model analysis shows troughing across the western CONUS this morning
that will propagate to the east, spinning up the potential for
severe thunderstorms across the Gulf Coast this afternoon. A
building ridge across the West Coast, will assist pushing an arctic
cold front across the Upper Great Lakes region Tuesday night into
Wednesday. Falling temperatures aloft will create a period of steady
LES through Wednesday afternoon before rising heights back winds
more from the south, ending LES. A weak clipper-system will bring
another quick chance for -SHSN on Thursday, mainly across the
Keweenaw and east. Global ensembles suggest rising heights and temps
into the weekend as positive 500mb height anomalies build across the
central and eastern CONUS. Deterministic models suggest a weak wave
to pass through the Plains to the north of Lake Superior on Friday
as a clipper wave traverses south and east across Canada Friday
night into Saturday. Both of these waves bring the chance of light
precipitation across the area, but confidence in specifics remains
on the lower side for now. Overall rising temps into the low to mid
30s with drier conditions going into the weekend.
Compared to the last few days, not much has changed in regards to
the forecast Tuesday night into Wednesday. Winds become more steady
from the NW overnight as 850 mb temps fall through the night. Snow
amounts remain close to the same with 3 to 5 inches in the NW wind
snow belts across the west and 4 to 6 across the east. These snow
totals are from Tuesday through Wednesday. Late Tuesday night into
Wednesday, 850 temps fall blo the DGZ as snowflakes may become
smaller...limiting visibility further at times.
Wednesday night going into Thursday, heights begin to rise as winds
back more from the south. A quick passing wave will move across Lake
Superior Thursday bringing weak associated WAA and isentropic lift.
This will bring snow showers primarily across the Keweenaw and east.
Expect any snow accumulations to remain light.
This weekend into Monday, 850 temps rise above 0C as Upper Michigan
gets a chance at a "December Thaw". It looks to remain dry through
the weekend, with any precipitation chances remaining light. Some
model differences show a passing low Friday into Saturday that looks
to remain north of the area. High temperatures will remain at or
above 30 degrees Friday through Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 633 PM EST MON DEC 16 2019
Under westerly winds, lake effect -shsn and mostly MVFR conditions
will continue at KCMX into tonight. Late tonight/Tue morning,
passage of a cold front should result in prevailing IFR conditions
setting in. At KIWD, the approach and passage of cold front late
tonight/Tue morning should bring in prevailing MVFR to occasional
IFR conditions. At KSAW, MVFR cigs should break out to VFR in the
next couple of hrs. VFR conditions will then continue until MVFR
cigs arrive with cold fropa Tue afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 421 PM EST MON DEC 16 2019
Main attention during this fcst issuance is the arctic cold front
that will sweep across Lake Superior on Tue. Front will reach
western Lake Superior late tonight and will exit the se part of the
lake around 18z. Tonight, expect westerly winds mostly in the 20-
30kt range. Winds on the w half of the lake will be closer to 30kt
late tonight, just ahead of the cold front. In the wake of the
arctic front passing on Tue, expect nw winds to 30kt, which will
continue into Tue night/early Wed morning. Incoming pres rises
combined with increasingly colder air flowing across the lake
support a good potential of gales to around 35kt Tue aftn/night and
into early Wed morning, at least over the e half of Lake Superior.
Thus, a gale warning has been issued for that part of the lake.
Winds will quickly diminish from w to e on Wed as a sfc high pres
ridge arrives. Should see a short period with winds under 15kt as
the ridge passes. After the ridge exits, expect an increase in
southerly winds heading into Thu, possibly up to around 25kt over
the e half of the lake. Approaching low pres trof on Fri will bring
a further increase in winds, again strongest across the e half of
Lake Superior where s to se winds up to 30kt are expected. Winds may
settle back some on Sat.
There will be some freezing spray tonight into Tue morning, but the
more significant freezing spray will arrive after the arctic cold
front passes. Heavy freezing spray will likely develop later Tue
aftn and continue into Wed morning. Heavy freezing spray warnings
have been issued for much of Lake Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Heavy Freezing Spray Warning from 10 PM Tuesday to 3 PM EST
Wednesday for LSZ251-267.
Gale Warning from 3 PM Tuesday to 8 AM EST Wednesday for
LSZ243>245-248>251-264>267.
Heavy Freezing Spray Warning from 3 PM EST /2 PM CST/ Tuesday to
1 PM EST /noon CST/ Wednesday for LSZ240>245-249-250-263-
264-266.
Heavy Freezing Spray Warning from 5 PM EST /4 PM CST/ Tuesday to
9 AM EST /8 AM CST/ Wednesday for LSZ162.
Heavy Freezing Spray Warning from 5 PM Tuesday to 11 AM EST
Wednesday for LSZ246>248-265.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...JAW
AVIATION...Voss
MARINE...Rolfson
Area Forecast Discussion
National Weather Service New York NY
1022 PM EST Mon Dec 16 2019
.SYNOPSIS...
A low pressure system will impact the region tonight through
Tuesday. A polar cold front approaches Wednesday and moves across
Wednesday night. Canadian high then pressure builds into the
region through Saturday, weakening Sunday and Monday, but
remaining the dominant feature in the weather pattern.
&&
.NEAR TERM /THROUGH TUESDAY/...
The forecast remains mainly on track. Minor changes were made
to hourly temperatures, dewpoints, and weather based on the
latest observations and trends. Made the intensity for the
remainder of the evening light as radar echoes have been
stronger aloft than they are closer to the surface. As a result
of the lighter intensity, not as much wet bulb cooling is
occurring and there is a general light sleet, light rain, light
snow mix occurring. Warm nose from RAP soundings show an above
freezing layer around 850mb moving in around midnight, which
would lead to some more freezing rain which already is in the
forecast for some parts of the area overnight.
Low pressure continues to develop over the Tennessee Valley with
a warm front well to the south across NC/VA border. This warm
front will gradually approach through tonight as the low nears
the northeast. Surface high pressure and ridging remains in
control into this evening. Steady precipitation should hold off
until large scale lift and better dynamics approach from the
south and west ahead of the warm front and low pressure.
The dry air currently in place will allow for evaporative
cooling and wet-bulbing as the precipitation intensity
increases. Even at the coast/NYC/LI, a brief period of
accumulating snow is possible. However, it should transition to
a mixture of snow and sleet and eventually plain rain early
Tuesday morning. Away from the NYC metro and coast, snow may
hang on longer as the heavier intensity of the precip and
northerly flow should hold the warm advection at bay for a few
hours longer. Eventually, the warm nosing aloft will win out and
transition the precip to a mixture of snow/sleet and freezing
rain. Model soundings reveal an isothermal layer in the
lower/middle levels which may promote moderate to heavy snow.
This will be brief near the city and coast, but likely last
several hours longer inland. There is also a deeper cold layer
just above the surface on soundings which may bring a prolonged
period of sleet as the warm nose melts the snow aloft.
The morning commute will see its greatest impacts inland and
away from the NYC metro and Long Island. The I-95 corridor in
southern CT and rest of interior will see a mix of freezing rain
and sleet during the morning commute.
Warmer surface temperatures will try to move inland through the
morning, but the northerly flow and further proximity to the
warm front should keep temperatures at or below freezing for
much of the day. Elsewhere, temperatures warm into the middle
and upper 30s with some locations on Long Island potentially
reaching 40.
The models seem to have a good handle of the track of the low
and location of the warm front through the day Tuesday. The main
uncertainty revolves around the timing of the transitioning
precipitation. Temperatures may also run a bit colder across
northern Long Island and northern NYC for a time between 3 am
and 6 am where some freezing rain may occur. However,
temperatures should rise above freezing during the morning
commute.
Total snow accumulations range from 2-4 inches away from the
coast to about an inch or less over NYC and Long Island. A
reasonable worst case scenario is around 5 inches inland to 2-3
near the coast. For freezing rain accretion, around 0.1 to 0.2
inches of ice are anticipated in the advisory area. Will have to
monitor any locations outside of the advisory that stay colder
and see freezing rain early Tuesday. An SPS or brief advisory
may be needed to account for this. Freezing rain amounts inland
could exceed 0.25 inches where through Tuesday where
temperatures do not rise above freezing.
Precip should taper off from west to east late in the day as the
low pressure moves offshore and N-NW flow takes over.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Lingering low chances on PCPN continue Tuesday evening as the storm
heads farther NE out to sea. PCPN types still in the form of rain
right at the coastal areas, but freezing rain and sleet still
possible inland. Weak high pressure then follows for the overnight
hours of Tuesday night, keeping us dry.
A cold front approaches on Wednesday, accompanied by a strong
shortwave. Moisture is lacking, but could be enough for a snow
shower or two in the afternoon to evening hours. The front exits by
midnight with a much colder air mass and gusty winds being ushered
in behind it. Lows Wednesday night drop into the teens for most
locations with some single digit readings well inland. Wind chills
late at night drop to near zero around the city, and down into the
single digits below zero elsewhere.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Deep-layered ridging moves into the Northeast Thursday through
Saturday with an extended period of dry weather as a sufficient
combination of moisture and lift remains lacking. Temperatures for
Thursday and Thursday night will be well below normal with highs
only in the 20s and lows again mostly in the teens.
The upper ridge flattens Saturday night with a weak shortwave aloft,
but weakened surface high pressure should still manage to keep us
dry through Sunday. High pressure then strengthens somewhat on
Monday as we`ll be in between two storm systems - one over SE Canada
and the other moving off the US SE coast. The air mass over us will
have had time to moderate, so expecting to see temperatures closer
to normal Saturday, and possibly even a few degrees above normal for
Sunday and Monday.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Low pressure approaches from the west overnight, and passes
south of Long Island late Tuesday.
Mainly VFR through about 04Z as dry air aloft continues to
prevent the ceilings from lowering with generally a mixture of
light rain and ice pellets falling across the area. MVFR
conditions are possible in some of the heavier precipitation
that moves through during this time frame, which could change
any precipitation to snow for a brief period, lowering
visibility, and this is reflected with a TEMPO group. Ceilings
and visibility then lower after 04Z as steadier precipitation
overspreads the area.
Snow or wintry mix will change to plain rain from south to
north (except for KSWF where snow will change to a wintry mix).
Around an inch or less of snow generally expected for the NYC
airports, but a period of icing is possible mainly for KTEB and
KEWR. Interior areas will have icing at least into Tuesday
morning. Precipitation ends from west to east after 18Z Tuesday,
but ceilings are likely to remain close to or below 1000 ft.
Light and variable winds become northeasterly around 10 kt late
tonight into Tuesday morning. Winds increase slightly late
Tuesday as they become northwesterly.
.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
.Tuesday night...Becoming VFR after 00Z. NW wind gusts to
around 20Z at times overnight.
.Wednesday...Mainly VFR. Pockets of IFR or lower possible
late afternoon and evening with isolated to scattered +SHSN. W
winds becoming NW and strengthening late.
.Thursday through Saturday...VFR.
&&
.MARINE...
Sub-SCA conditions are expected through tonight. Winds on the
waters east of Moriches Inlet increase to around SCA gusts
Tuesday morning and seas will build on the ocean with low
pressure passing across the waters. Have issued an SCA for the
ocean, first east of Moriches Inlet at 11z Tuesday, and for the
remaining ocean waters at 17z as seas build.
Winds and seas remain at advisory criteria levels Tuesday night on
the ocean. Winds diminish on Wednesday morning, however ocean seas
probably remain elevated. Winds pick up ahead of a cold front
Wednesday afternoon with the cold front passing through Wednesday
evening. Gales will then be possible on all waters Wednesday night.
Winds subside on Thursday, but with advisory level conditions as the
pressure gradient remains relatively tight over the region. A high
pressure ridge then brings more tranquil conditions on all waters
for Friday and Saturday.
&&
.HYDROLOGY...
A widespread precipitation event tonight through Tuesday will
bring a liquid equivalent of around an inch. The precipitation
will mainly be frozen away from the coast. No hydrologic impacts
are anticipated.
No significant precipitation is expected Tuesday night through the
weekend.
&&
.EQUIPMENT...
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) is still
operating at reduced power.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 6 PM EST Tuesday for CTZ005>008.
Winter Weather Advisory until 10 AM EST Tuesday for CTZ009>012.
NY...Winter Weather Advisory until 6 PM EST Tuesday for NYZ067>070.
Winter Weather Advisory until 10 AM EST Tuesday for NYZ071.
NJ...Winter Weather Advisory until 6 PM EST Tuesday for NJZ002-103.
Winter Weather Advisory until 10 AM EST Tuesday for NJZ004-
104>108.
MARINE...Small Craft Advisory from noon Tuesday to 6 PM EST Wednesday
for ANZ353-355.
Small Craft Advisory from 6 AM Tuesday to 6 PM EST Wednesday
for ANZ350.
&&
$$
SYNOPSIS...JC/DS
NEAR TERM...JC/JM/DS
SHORT TERM...JC
LONG TERM...JC
AVIATION...JP
MARINE...JC/DS
HYDROLOGY...JC/DS
EQUIPMENT...
Area Forecast Discussion
National Weather Service Tallahassee FL
743 PM EST Mon Dec 16 2019
...SEVERE WEATHER STILL POSSIBLE ACROSS PORTIONS OF SOUTHEAST
ALABAMA AND THE FLORIDA PANHANDLE LATE TONIGHT AND SPREADING
EASTWARD INTO THE DAY ON TUESDAY...
.UPDATE...
The previous forecast of a marginal to slight risk of severe
weather from late tonight into the day on Tuesday still looks on
track. Looking at the forecast environment from the RAP runs this
evening, the best overlap of CAPE and shear is expected to arrive
in our far western counties after midnight. RAP forecast soundings
near Dothan around 3 am CDT show SBCAPE values over 500 j/kg with
minimal CINH, low LCL heights, and strong low level and deep
layer shear (near 30 and 50 knots, respectively). The hodograph is
strongly curved in the low level with 0-1 km SRH values over 250
m2/s2. Some of the HRRR runs this evening have shown new
convection developing out ahead of the main line currently in
Mississippi later tonight. If this convection develops and the RAP
is correct about the forecast environment, then a tornado threat
could develop across portions of southeast Alabama and the Florida
panhandle late tonight along with the potential for damaging
straight line wind gusts. This threat would spread eastward across
the remainder of the area through the morning hours and into the
early afternoon.
The main limiting factors and uncertainties include the fact that
the 18z NAM and GFS are a little weaker overall with both the
instability and shear, and there is uncertainty on whether or not
new convection will develop ahead of the main line later tonight.
The main things to watch on the mesoscale tonight will be if the
surface winds remain backed across the western counties and how much
the surface dewpoints increase in southeast Alabama. The RAP runs
generally forecast upper 60s dewpoints reaching Dothan, which is a
degree or two higher than other guidance. These small differences in
surface dewpoints and wind direction can really make a difference in
the resulting instability and shear.
&&
.PREV DISCUSSION [652 PM EST]...
.NEAR TERM [Through Tuesday]...
Currently a surface low pressure system is developing across
northern Louisiana and southern Arkansas, which is expected to
propagate to the north and east through the Tennessee valley today
and tomorrow. This system is expected to bring unsettled weather to
our western areas later this evening. Scattered thunderstorms will
be the main storm mode ahead of the cold front which is expected to
move through the region through the very early morning hours in our
western and central areas. The cold front is expected to clear the
eastern zones of our region by the early evening hours on Tuesday.
Some storms along the cold front may become severe. This entirely
depends on the timing of the cold front, and whether some
instability can hang around before the main forcing for ascent lifts
to our north.
Tonights low temperatures will be above normal with much of the
region holding onto the 60s. Highs across the region will depend
greatly on the timing of the front. Our eastern zones will likely
peak into the mid 70s before the front arrives, but areas in the
Florida Panhandle and SE Alabama will struggle to reach the upper
60s before the front passes through. Temperatures will slowly
decrease throughout the day in these areas.
.LONG TERM [Tuesday Night Through Monday]...
Much cooler and drier air will work in behind the cold front with
temperatures dipping into the 30s for much of the area Tuesday
Night. Chilly conditions on Wednesday as high pressure builds in
with temperatures struggling through the 50s. For the rest of the
workweek we`ll see a slow moderating trend with chilly locally
frosty mornings and mild sunny afternoons as temps rebound into
the 60s for most of us.
The weather then gets interesting for the weekend as some manner
of low will likely form in the Gulf as a strong upper wave digs in
from the NW. It needs to be noted up front that the
predictability with this system...as demonstrated by incredible
dispersion among model ensembles and big model to model
differences...is very low. For now given that we`re looking at
days 5-7 we`ll follow the general trends of our blended guidance
and maintain low PoPs and seasonable temperatures through the
weekend. Stay tuned to see how this one evolves...especially as we
get into mid-week and the energy associated with the digging
upper wave begins to get sampled upstream.
.AVIATION...
[Through 00Z Wednesday]
Low cigs and vsbys are expected tonight ahead of a cold front w/some
patchy fog possible for TLH and VLD in the overnight hrs. A line of
TSRA (some may be strong to severe) will arrive at DHN and ECP first
around daybreak, and move thru other terminals in the 12-13z
timeframe. SW winds (may be gusty at times) will shift quickly to NW
as front passes, and become northerly in its wake. Conds should
improve to MVFR after frontal passage for all terminals.
.MARINE...
Moderate southerly winds tonight will become strong and northerly
as a cold front moves through Tuesday afternoon and evening. A
line of thunderstorms will accompany the frontal passage on
Tuesday. Small Craft Advisory conditions are expected Tuesday
evening through Wednesday night behind the front. Winds will then
decrease into the moderate range for the rest of the work week.
.FIRE WEATHER...
An approaching cold front will cause southwesterly transport winds to
veer to the northwest and north, and bring showers/storms to our area
Tuesday thru early Wednesday. High dispersions are expected for
east/southeast Big Bend late Wednesday morning thru the afternoon.
Otherwise, red flag conditions are not expected as RH values will remain
above critical thresholds.
.HYDROLOGY...
Rainfall amounts over the next 24 hours will generally be an inch
or less and cause only minor rises on area waterways. The next
chance of rain for the area will be next weekend as low pressure
develops in the Gulf.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is requested. Spotters should safely report
significant weather conditions and/or damage by calling the office or
tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 61 74 38 55 31 / 30 80 30 0 0
Panama City 64 71 39 54 35 / 60 90 10 0 0
Dothan 59 68 35 51 29 / 80 90 0 0 0
Albany 63 70 38 53 31 / 50 80 10 0 0
Valdosta 61 74 40 54 32 / 20 90 50 0 0
Cross City 60 76 43 58 34 / 10 80 60 0 0
Apalachicola 64 73 41 54 36 / 40 80 30 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 1 AM EST /midnight CST/ Tuesday for
Coastal Bay-South Walton.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...DVD
NEAR TERM...Bunker
SHORT TERM...Johnstone
LONG TERM...Johnstone
AVIATION...IG
MARINE...Johnstone
FIRE WEATHER...IG
HYDROLOGY...Johnstone
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Tuesday)
Issued at 310 PM CST Mon Dec 16 2019
Light snowfall along and east of the Turnpike ends this evening
with a cold night in store.
A strong H500 shortwave and embedded speed max noted distinctly
on water vapor imagery is lifting out of Oklahoma into
southeastern Kansas. With this trough axis lifting through eastern
Kansas, the mid-level H600-700 baroclinic zone associated with
the ongoing snowfall is also beginning to shift eastward. This
trend should continue through the remainder of the afternoon and
evening, with snow ceasing across the area by 6 to 7 pm. Narrow
banding features noted in radar imagery associated with the
realization of minor CSI may result in another half inch to inch
of snowfall before the event winds down.
Attention then turns to temperatures and cloud cover in the wake
of this system. Despite the ample high clouds, visible satellite
imagery does show a steady erosion of the low-level stratocumulus
cloud deck over far northern and central Kansas. At this going
rate, clouds should clear the area by midnight. It is interesting
that the RAP and HRRR saturate the near-surface profiles and
redevelop a stratus shield in eastern Kansas overnight. The
saturated layer is quite shallow and might be an artifact of the
weak CAA overnight. The NAM/GFS are devoid of such a feature and
for how have continued with the going forecast of clearing skies.
However, this will be an item worth monitoring overnight as it
will have a large impact on low temperatures tonight.
With the fresh snowpack and subtle surface ridge axis shifting
overhead, trended the forecast on the colder side of the guidance
envelope. Even if clouds hold for most of the night, a short-
lived clearing could result in a rapid temperature plummet. With
an amplified longwave ridge building out west and broad surface
ridging settling in for Tuesday, clearing skies and light winds
are expected. While winds do back to the west, WAA will not arrive
until after sunset. The residual snowpack should persist through
the day and have nudged highs closer to the freezing mark given
the dry nature of the airmass in place, which should be easily
modulated by the snowpack.
.LONG TERM...(Tuesday night through Monday)
Issued at 310 PM CST Mon Dec 16 2019
Little sensible weather is forecast through next weekend with a
gradual warming trend.
Longwave ridging dominates the pattern for the extended with
predominantly southwesterly flow ushering in warmer air through
next weekend. The one exception is Thursday into Friday as a
decaying shortwave propagates through the mean longwave ridge.
This will usher a very weak boundary into the Central Plains, but
no precipitation is forecast with its passage. Temperatures for
Wednesday through Friday hinge on how quickly the snowpack melts.
The going forecast for eastern Kansas is likely on the high side
of the guidance envelope, with some raw solutions still depicting
highs in the 30s to low 40s through Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 531 PM CST Mon Dec 16 2019
Expect VFR conditions through 6Z TUE. Through the early morning
hours of Tuesday, patchy freezing fog may develop at the terminals
while a few models show IFR stratus ceilings developing which
would limit the dense freezing fog. At this time I placed
scattered stratus with bases of around 800 feet and added BR to
lower visibilities down to 1 mile. If skies stay clear then there
may be freezing fog at the terminals between 8Z and 13Z MON with
visibilities of 1/2 SM or less. By 14Z, any freezing fog should
have mixed out. After 14Z, expect VFR conditions at the terminals.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM CST this evening for KSZ059.
&&
$$
SHORT TERM...Skow
LONG TERM...Skow
AVIATION...Gargan