Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/24/19
Area Forecast Discussion
National Weather Service Binghamton NY
1024 PM EST Sat Nov 23 2019
A system moves in from the southwest and brings rain and a
wintry mix to the area overnight into Sunday morning. That
system will rapidly intensify off the coast Sunday and could
bring a period of heavy snow to the Catskills. High pressure
returns with dry weather and a gradual warming trend Sunday
night through Tuesday. Next storm system arrives midweek, with
periods of rain and wind, then colder temperatures behind it.
.NEAR TERM /THROUGH SUNDAY NIGHT/...
Concern increases that a mesoscale snowband could set up on the
west side of the developing mid level cyclone from 12z-15z
Sunday as far west as Oneida county south to Broome Co and even
down into Luzerne County of PA. Both the 00z NAM, NAMnest and
the 02z HRRR are now showing a 700 mb low tracking across
southern PA to NJ with a band of frontogentical forcing across
these areas. The band would be transient but could lead to
quick advisory amounts from Oneida Co down to Broome and
Wyoming/Luzerne/Lackawanna Counties and into the Poconos. Warning
criteria snows are going to be possible in Delaware/Otsego and
northern Sullivan counties if the latest HRRR and NAM are true.
It is going to be close as thermal profiles are marginal so at
this juncture not enough data or observational evidence to make
wholesale changes. We need to see more model runs, WPCs
guidance and what the other WFOs come up with before jumping.
Briefed mid shift on possibilities. For now still going with
winter weather advisory much of northeast PA to Delaware and
Otsego, Sullivan counties in NY. I am forecasting less than one
inch in the valleys of northeast PA with 1-3" over the higher
terrain. We also expect up to .1 inches of ice in the Poconos.
Farther north, going with 3"-6" over Delaware and Otsego
counties and just very light icing. Rest of area will see mainly
rain overnight with patchy freezing rain over the higher
terrain so issued an SPS to cover.
***Wintry mix and snow late tonight through Sunday***
A complex winter storm will start to impact the region later
tonight through Sunday. Precipitation will start as a wintry mix
across NE PA with freezing rain most likely across higher
elevations of the Poconos. However, WAA advection aloft should
change things over to plain rain for a period overnight, but
expecting cooling after 700 mb low passes the area early
tomorrow morning and a transition to eventually all snow is
Upper level low tracks across the Ohio Valley late tonight with
a weak surface low initially tracking up the Ohio River Valley.
However, that low will reemerge off of Delmarva and rapidly
intensify tomorrow morning south of Long Island and head
east/northeast along the New England Coast through the day
Sunday. Although there is no real cold air already in place
anywhere in the region, as this system intensifies, dynamic
cooling will occur. Models indicate strong frontogenesis
developing and aligning south to north across our eastern
forecast area. Forecast Bufkit soundings indicate a period
tomorrow morning with strong omega through a saturated dendritic
growth zone from Monticello on north to Oneonta. Thinking is
that a band of heavy snow with snowfall rates greater than 1
inch per hour will develop tomorrow morning and exactly where
this band forms will determine who sees a nice little thumping
of snow tomorrow.
For now, with temperatures forecast to be near the freezing
mark, did not go too crazy with snowfall accumulations. With
highest amounts in the 3 to 6 inch range across Delaware and
Otsego Counties, but there is concern that if a band does
develop and temperatures are slightly cooler, then some areas
could come out with over 6 inches of snow tomorrow. Therefore,
have just went with winter weather advisories for now, but we
will have to monitor how the event unfolds tomorrow morning with
where the band sets up and the transition from rain to snow.
Further south into NE PA...temperatures will be close to
freezing or just below as rain moves in later tonight and there
could be a period of light freezing rain/icing. So although snow
amounts are well below criteria in these zones, have decided to
hoist an advisory due to the ice threat. There is uncertainty
though with surface temperatures. With highs today climbing
into the 40s, will a glaze of ice even be able to form on warm
road surfaces tonight. For that reason, have not included
Luzerne County in this advisory and will have to keep an eye on
this to see if an SPS or short fuse advisory is needed if icing
does develop. It is possible that there are only a few pockets
of slick spots, especially on exposed bridges and overpasses.
Precipitation moves out of the area tomorrow afternoon, but
there will be a very slight chance for some freezing drizzle or
light freezing rain across the north tomorrow night in the
higher terrain on either side of the Mohawk Valley. The
discussion written last night in the short term still looks good
for this time period.
Previous discussion at 4 am Sunday... Westerly flow will exist
Sunday night with some lake moisture under a weak subsidence
inversion. 850mb temperatures will be 4-5 degrees Celsius below
freezing, which along with the shallowness of the moisture
leaves doubts as to whether precipitation will occur at all. The
NAM and Canadian regional suggests at least spotty light
precipitation off of Lakes Erie- Ontario; GFS-ECWMF are dry.
Even if it does occur, lowest temperatures in the saturated
layer may not be cold enough for crystal formation and thus
patchy drizzle/freezing drizzle could be the result. In the
possible drizzle area, the potential for temperatures reaching
freezing or slightly below, will be higher terrain of southern
Madison- far southern Oneida-far northern Otsego Counties, as
well as northern Oneida County. But of course, that risk is
conditional on precipitation happening at all which is in
question. If anything manages to occur it will be very light.
.SHORT TERM /MONDAY THROUGH TUESDAY/...
4 AM Update...
Surface ridge will move through the region Monday, though a
passing shortwave aloft will probably still cause a good amount
of cloud cover with highs mainly in the 40s. South of the Twin
Tiers-Catskills, at least partial sunshine should be managed.
Monday night into Tuesday, we get into southwesterly return flow
at the surface as well as warm air advection aloft. Eventually
this will mean increasing moisture, but at least through daytime
Tuesday conditions should remain dry with only gradually
thickening clouds. After lows mainly in the 30s Monday night, we
get a good bump in temperatures to mid 40s-mid 50s for Tuesday.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
405 AM Update...
Things turn active during the long term period, with potential
for a deep showery low pressure system Wednesday followed by
gusty winds and colder temperatures through Thanksgiving
including possible lake effect snow.
Operational models are actually in surprisingly good agreement,
on a digging trough in the Central Rockies Tuesday, initiating
cyclogenesis in the Southern Plains to Midwest Tuesday night,
zipping through the Great Lakes Wednesday as a strong surface
low to the tune of low 990s mb range. This is depicted in tandem
with the upper trough becoming a compact upper low yet one which
translates fairly quickly across the northern states.
With warm air advection ahead of the system, and the projected
track of the low being generally through northern New York into
New England, it appears that mainly rain will occur with the
system passage Tuesday night into Wednesday. However, strength
of the low would likely induce strong pressure rises and steep
low level lapse rates later Wednesday with gusty winds. Gusts of
30-40 mph look attainable based on current models; we will need
to monitor trends. Continued cyclonic northwesterly cold air
advection in the wake of the system, will lead to a chilly brisk
Thanksgiving with persistent stiff winds.
Biggest point of uncertainty with this system, is will the
system slow down just enough on its way out, to allow at least
some synoptic wrap around moisture to join the lake effect
moisture Wednesday night into Thursday. The Canadian-Global and
to a lesser degree the ECMWF suggest a more favorable window of
lake enhanced/brief synoptic upslope snow southeast of Lake
Ontario late Wednesday night into at least early Thursday; the
GFS meanwhile is more progressive and thus very little
opportunity for lake effect to organize/join forces with any
wrap around moisture. We have several days to sort this out,
but given the holiday travel this is worth monitoring.
At this time, Friday appears quite cool with continued northwest
wind, yet also building high pressure and thus dry.
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Conditions will gradually deteriorate throughout this
evening/overnight from south to north. KBGM, KELM, and KITH will
likely remain at VFR until 04Z-06Z, with KSYR and KRME likely
remaining VFR until 08Z-09Z. KAVP is already at MVFR as of 00Z
and will likely bounce back and forth between VFR and MVFR for a
few hours before deteriorating further.
Conditions at all terminals eventually lower to the IFR range
late tonight/early Sunday morning as a wintry mix of
precipitation moves in, perhaps with the exceptions being at
KSYR and KRME (as of now expecting ceilings to bottom out in the
Fuel Alternate category at these two terminals). Additional
visibility restrictions are possible in steadier precipitation,
especially as the wintry mix changes over to snow at most
locations Sunday morning. Then expecting improvement to MVFR at
most terminals early Sunday afternoon and eventually back to
VFR by the end of the TAF period as drier air returns from the
Winds tonight will be mainly from the southwest at less than 10
knots, before shifting to a more northwesterly direction Sunday
Sunday night through Tuesday...VFR expected.
Wednesday...A system bringing rain may pass through the region
with associated restrictions. Strong, gusty winds also possible.
Thursday...Improvement to VFR after morning snow showers.
PA...Winter Weather Advisory until 1 PM EST Sunday for PAZ040-044-
NY...Winter Weather Advisory until 1 PM EST Sunday for NYZ062.
Winter Weather Advisory until 3 PM EST Sunday for NYZ046-057.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
911 PM EST Sat Nov 23 2019
As low pressure lifts to our northeast tonight, its associated
cold front will move off the Southeast Coast. In its wake, cool
high pressure returns on Sunday with another front expected to
impact the area by the middle of next week.
.NEAR TERM /THROUGH SUNDAY/...
As of 910 PM: The pre-frontal precipitation shield has moved east of
the forecast area this evening. Residual showers are filling in a
bit in the developing northwest flow over the mountains, and
temperatures are starting to tumble there, with some high elevation
30s already evident. Wind and snow showers will be the main concerns
for the bulk of the overnight across the mountains, with breezy but
clearing conditions expected across the foothills and piedmont.
The snow and wind forecasts generally remain on track for the
mountains overnight as cold advection develops in earnest and low-
level upslope moisture remains fairly deep, at least for a short
while early Sunday morning. Will continue to feature around 3 inches
of snow around Mt. Mitchell and the higher ridge tops across the
Smokies, but with little chance of 2 inch or greater amounts below
about 4500 feet. The RAP and NAM continue to depict slightly
stronger 850 mb flow in the cold advection, so the northern Blue
Ridge Mountain area Wind advisory still looks well placed. Cannot
rule out some damaging wind gusts on the highest ridge tops, but
again, not low enough for an upgrade to a warning or an expansion
East of the Blue Ridge, clearing should occur through the early
morning hours Sunday, so expect plenty of sun through the day. Winds
will be gusty in the morning, but the pressure gradient relaxes
quickly by midday. Temps will still manage to get up to a category
or so below normal because of the insolation and downslope flow.
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 133 PM EST Saturday: In the wake of the weekend system,
the upper pattern goes nearly zonal for the first part of the
new week. A weak short wave will pass Sunday night with little
fanfare. High pressure should dominate on Monday as it moves across
the Deep South and then off the southeast coast Monday night,
which should keep our weather fair. Temps will stay right around
normal, or maybe just below by a degree or two.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 2:25 PM EST Saturday: the extended fcst picks up at 12z on
Tuesday with heights steadily increasing over the region as broad
upper trofing digs down across the Southern Rockies. Over the next
few days, the upper-lvl pattern remains fairly progressive with
the above-mentioned upper trof lifting up and over SE CONUS upper
ridging late Tues into Wed. By late Wed, the upper trof axis is
expected to be passing well to our north and then offshore by early
Thursday. After this, the upper ridge amplifies again and remains
over the Eastern CONUS into next weekend. At the sfc, dry high
pressure will still be over the region as the period begins early
Tuesday. During the day on Tues, an impressive low gets ejected
from the Great Plains and then lifts NE towards the Great Lakes.
As it does, the system will lift a moist warm front over our area
late Tues. On Wed, the system`s cold front will move rapidly thru
the fcst area and is expected to be moving offshore by late Wed
into early Thurs. All precip associated with this system is still
expected to be liquid. In its wake, drying high pressure will spread
back over the CWFA from the NW. The high remains centered just north
of the Great Lakes as it slowly drifts eastward thru the end of the
period. This will keep NLY to NELY low-lvl flow over the fcst area
into Sat. By the end of the period next Sat, the long-range models
develop another strong low over the Plains and lift another warm
front over the fcst area by the end of the period. High temps will
start out above normal on Tues and Wed and drop just below normal
for the rest of the period. Lows should remain above normal thru
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Conditions will improve rapidly from IFR
through MVFR to VFR over the next couple of hours as a front moves
east of the region and gusty, drying westerly winds develop. KAVL
will be the main exception, where northwest flow moisture could lock
in MVFR conditions through the overnight hours. Anticipate gusty
winds to develop with the onset of cold advection, and gusts to near
30 kt will be possible at KAVL at times, with 20+ kt east of the
mountains. The gradient will gradually relax through Sunday with
foothill winds staying mainly WNW to WSW, but remaining NW and
occasionally gusty at KAVL. Any mountain snow showers overnight
should remain generally N and W of KAVL.
Outlook: Dry high pressure and VFR conditions will return behind the
departing cold front Sunday. VFR conditions should persist through
early next week before another front crosses the region mid-week.
02-08Z 08-14Z 14-20Z 20-00Z
KCLT Med 74% High 100% High 100% High 100%
KGSP High 95% High 100% High 100% High 100%
KAVL Med 70% Med 69% High 100% High 100%
KHKY High 95% High 100% High 100% High 100%
KGMU High 95% High 100% High 100% High 100%
KAND High 98% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
NC...Wind Advisory until noon EST Sunday for NCZ033-049-050-501-503-
Area Forecast Discussion
National Weather Service Melbourne FL
1003 PM EST Sat Nov 23 2019
Cold front moving through north Florida this evening, will move
into central Florida overnight with rain chances increasing as
bands of showers ahead of this boundary work their way into the
area. Have increased PoPs just slightly, with greatest rain
chances around 50-60 percent along and northwest of a line from
Lake Kissimmee to the Cape, to 20-30 percent across the Treasure
Coast and Okeechobee County. HRRR model runs have actually been
showing some lightning activity as showers move into the area
overnight. However, with any instability extremely limited,
greatest dynamic forcing farther north of the region, and absence
of lightning thus far this evening ahead of the front, will keep
any mention out of the forecast. Could however see some brief
gusty winds with showers as low level W/SW winds increase ahead of
the approaching front overnight.
Skies will become mostly cloudy after midnight with lows falling
into the upper 50s northwest of I-4 to low-mid 60s farther south.
.AVIATION...Tempo IFR/MVFR conditions will occur in bands of
showers that move in ahead of front. These scattered showers
currently approaching KLEE-KDAB will move across the area
overnight. A period of MVFR cigs may follow behind showers and
front, but conditions are expected to rapidly improve from north
to south tomorrow as drier air moves into the area.
.MARINE...SW/W winds will increase to 15-20 knots over much of
the waters tonight, to around 20 knots offshore of Volusia and
Brevard counties overnight as front begins to move through the
area. Will keep Small Craft Exercise Caution headlines tonight
for everywhere but nearshore Treasure Coast where winds will be
closer to 10-15 knots. Still not planning on issuing an SCA
offshore due to the short duration of stronger offshore flow
overnight, and with seas only expected to build to 5 feet.
.PRELIMINARY POINT TEMPS/POPS...
DAB 60 68 49 68 / 50 10 0 0
MCO 62 72 48 70 / 50 10 0 0
MLB 65 77 53 72 / 30 30 0 0
VRB 64 78 52 72 / 30 30 0 0
LEE 59 69 48 68 / 60 10 0 0
SFB 60 71 47 70 / 60 10 0 0
ORL 62 72 48 70 / 60 10 0 0
FPR 63 79 53 73 / 20 30 0 0
Area Forecast Discussion
National Weather Service Marquette MI
1033 PM EST Sat Nov 23 2019
Issued at 1025 PM EST SAT NOV 23 2019
Mostly clear skies over the central and eastern portions of the
UP have allowed temperatures to fall quickly this evening,
particularly for locations with greater snowpack. Temperatures
were already in the teens, well below guidance, for these areas
but cloud cover was quickly moving in from the west associated
with a weak shortwave. Lowered the overnight min temperatures a
few degrees from the current observations as they should steady
and moderate some as clouds move in. The rest of the forecast is
on track, kept low PoPs across the north. With dry air in place
it will be hard for the precipitation to reach the ground.
However, where it does there could be enough warm air aloft to
result in very light freezing rain.
.SHORT TERM...(This evening through Sunday)
Issued at 243 PM EST SAT NOV 23 2019
Another mostly quiet short-term period on tap tonight and tomorrow.
Water vapor satellite shows the narrow, positively tilted trough
that`s been responsible for some very light, widely-scattered
flurries and showers over Lake Superior and clipping the Keweenaw.
That trough will continue to push east out of the area this evening.
Away from the lake, clear skies have allowed temps to rise to near
40 or in a few cases into the 40s. However clouds will increase
again from west to east tonight ahead of a short wave and weak upper-
level jet racing through Ontario and clipping Lake Superior. Right
now it looks like the lion`s share of the forcing strong enough for
precip will remain out over the lake, but the RAP and a few CAMs
resolve a quick-hitting band of precip pushing east across the U.P.
early Sunday morning (generally 09-14z) with the best chances (but
still only 40% or so) over the Keweenaw and in Luce County. Even
though there will be some low level dry air to saturate before
precip falls tonight/tomorrow morning, GFS and RAP model soundings
both show wet bulb temps above freezing from just above the surface
to about 800 mb, give or take. That means any precip that falls over
land could be freezing rain where the surface temps are cold enough.
Thankfully, as stated before, precip chances are low, and QPF is
0.02" at most so not expecting any impacts from this. But should
this band of precip overperform, there could be some slick spots
in the morning.
Heights aloft rising behind this short wave should allow for at
least a period of partial clearing over the west and away from Lake
Superior Sunday afternoon before high clouds filter in from the
southwest in the evening. Over the Keweenaw and east, however,
onshore flow with ambient temps just cold enough for shallow lake
effect saturation will keep low clouds in place and probably allow
for some light drizzle east as well. Outside of these areas, went
with the median of the models giving highs around 40 to the mid 40s
over the south-central. Another chance to get a car wash in if you
didn`t do it today!
.LONG TERM...(Sunday night through Saturday)
Issued at 347 PM EST SAT NOV 23 2019
Models suggest that a quasi-zonal pattern with wnw mid/upper level
flow through the northern CONUS will give way to troughing over the
west through the first part of next week. The trough is expected to
slowly move into the central CONUS by next weekend as ridging over
the Great Lakes slides to the east. temps should remain near or
slightly above seasonal averages through Tue with slight cooling
Sunday night into Monday, another stronger shrtwv with stronger
WAA/isentropic lift ahead of it will move through northern Ontario.
Some ra/sn will be possible but with little or no accumulation as
the stronger forcing remains to the north and moisture remains
Mon night into Tue, although instability will be marginal with 850
mb temps only to around -7C, some light W to NW flow LES may be
possible into the KEweenaw as a weak sfc trough moves through.
Tue night into Wed, Models have trended slightly to the northwest
with the strong neg tilt shortwave and deepening sfc low lifting
northeast from the srn/cntrl plains. Even though the models spread
is decreasing, uncertainty remains with the track/timing. The
consensus and ensemble means take the sfc low through or near cntrl
lower Michigan. If this holds up, much of Upper Michigan would be in
line for moderate and possibly heavy snow with additional
lake/terrain contributions north. Cold enough air will be pulled in
for nw-n flow LES as 850 mb later Wed into Wed night behind the
departing system as 850 temps drop to around -10C.
Thu-Sat, drier weather is likely to move in Thu with sfc and mid
level ridging building into the area. Pcpn chances increase by
Friday into Sat as a WAA pattern develops ahead of the next low
developing over the plains associated with the advancing mid level
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 630 PM EST SAT NOV 23 2019
VFR conditions expected to prevail at IWD and SAW through the TAF
period. A few light showers could affect KCMX and KSAW overnight
but did include in the TAFs due to low probabilities and brief
durations. MVFR CIGS will develop Sunday morning with onshore
flow and orographic forcing at KCMX. Added mention of LLWS to KSAW
for a brief window Sunday morning as low level winds strengthen
above a shallow inversion. Shallow moisture moving into the area
tomorrow afternoon will result in some low level cloudiness at
KIWD, hinted at this with scattered low clouds toward the end of
the TAF period.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 243 PM EST SAT NOV 23 2019
20-30 kt WSW winds continue across the lake this afternoon. Winds
will briefly relax to about 20 kts this evening but quickly
restrengthen to 25-30 kts on the western half of the lake early
Sunday morning. These winds up to 30 kts will spread east across the
eastern lake during the day on Sunday, but then become very light
Sunday night as slight ridging passes over the lake. Winds then
increase back to 20-30 kts on Monday with broad low pressure moving
through Ontario and clipping Lake Superior. A strong low pressure
system is still lurking in the long range forecast, right now likely
to make its closest approach on Wednesday. The trend was towards the
south and east (and thus away from significant impacts to Lake
Superior) but today`s model runs have shifted back west somewhat.
The models will probably continue to flip back and forth slightly on
the exact track the next few days so the bottom line is that the
midweek period should continue to be watched for stronger winds even
though confidence remains low.