Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/17/17
Area Forecast Discussion
National Weather Service Binghamton NY
737 PM EST Sat Dec 16 2017
.SYNOPSIS...
High pressure will build in overnight, ending the few remaining
evening flurries, and keeping our weather quiet into Sunday.
Another passing disturbance will bring a chance for light snow
Sunday night, followed by temperatures turning a bit milder
Monday into especially Tuesday.
&&
.NEAR TERM /THROUGH SUNDAY/...
730 PM update...
Surface ridge of high pressure is nosing into the region,
drying out the atmospheric column while rapidly diminishing the
light snow that had been falling for much of today. Shallow
stratocumulus covers all of Northeast PA and most of Central NY.
A stray lingering flurry or two will still be possible for a
couple more hours but things are winding down quickly. North of
the NY Thruway, the sky has cleared out, which along with fluffy
layer of snow is allowing temperatures to radiate even faster
than the quick rate that had been forecast. Adjustments were
made for the continued erosion of clouds across the northern
zones to the western Catskills overnight, as well as temperature
details. Generally speaking, where clouds persist - Northeast
PA to Southern Tier NY - lows will be in the teens but where
the sky clears in other parts of Central NY single digits will
be common. In fact, a chunk of northern Oneida County will
probably reach below zero. Despite adjustments to these
details, overall forecast is mostly going as planned.
Previous discussion...
As of 130 PM, a large area of lake effect snow show continues
to affect our NY counties, with moderate snow observed near the
Onondaga / Cayuga / Cortland county borders.
None of the mesoscale models are doing a particularly good job
diagnosing the LES this afternoon, so we populated the grids
with a blend of RAP and HRRR and amended based on current
observations.
Bottom line is we expect another half-inch to an inch of
accumulation today downwind of the lakes, with slightly higher
amounts in isolated squalls.
High pressure will bring dry conditions to our region tonight
and Sunday.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
A wave of low pressure will slide eastward across the Great
Lakes Sunday night. Snow accumulations will be light, mainly
from a few tenths of an inch to an inch. Temperatures will range
from the teens over Oneida County to the upper-20s over Luzerne.
Warm advection will increase on Monday when a cyclone over
Ontario Province pulls southwesterly flow into NY and PA. A mix
of rain and snow showers is forecast. A wide variability of
temperatures, from the middle-30s over the Western Mohawk
Valley to the lower-40s in the Wyoming Valley, is expected
across the region.
Temperatures falling into the lower and middle-30s will cause
another rain/snow mix Monday night. Little accumulation is
forecast.
Tuesday will be mild with rain showers tapering off.
Temperatures will reach the 40s.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Cold front moves through the forecast area Tuesday night.
Precipitation is expected to change over to snow as the boundary
layer cools in wake of the front. Given the moisture depth from
forecast soundings, low-level flow, and water temperatures over the
southeastern part of Lake Ontario, we could see a decent lake-effect
snow event set up over northern parts of the forecast area. As such,
precipitation probabilities will be greatest over this region. The
odds of seeing snow will start to diminish by Wednesday night, after
a shortwave trough axis shifts east of the region.
Surface high pressure is forecast to move into the region under a
nearly zonal flow aloft by Thursday, resulting in what`ll likely be
the driest day of the upcoming week. That`ll likely be short-lived,
though, as synoptic scale lift ahead of a deepening storm system in
the Plains ushers the possibility of precipitation back into the
region by Thursday night. Warm advection occurring in a
southwesterly flow ahead of the next cold front should result in the
snow at least mixing with (if not changing to) a cold rain in most
areas by Friday afternoon.
Temporal and spatial uncertainty increases in the Day 6-7 time frame
between the major medium range models. In general, the cold front
should move west to east across the forecast area Friday night, with
precipitation changing back to snow in wake of the front. The snow
showers should continue across parts of the region into Saturday.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
A weak band of snow will continue to impact KITH, KELM, KBGM and
KAVP through about 02-03Z this evening with MVFR vsbys and cigs.
After 03Z, conditions are expected to become VFR at all
terminals. These conditions will persist tonight and most of the
day Sunday. The next system will approach from the sw during the
afternoon with ceilings likely becoming low-end VFR at KELM,
KAVP, and KBGM before 22Z.
Outlook...
Sunday night to Tuesday...Possible restrictions in rain or snow
showers.
Wednesday...Restrictions possible again in lake effect snow
showers mostly in central NY.
Thursday...VFR possible.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...MDP
NEAR TERM...DJP/MDP
SHORT TERM...DJP
LONG TERM...DAB
AVIATION...BJT/DJP
Area Forecast Discussion
National Weather Service Duluth MN
545 PM CST Sat Dec 16 2017
.SHORT TERM...(This evening through Sunday)
Issued at 303 PM CST Sat Dec 16 2017
Radar has one linear band of heavier snow over the north shore
and extending out to the Apostles otherwise all is quiet.
High pressure to our northeast has been fighting a low to our
southwest. Short term model guidance has had a rough go today
without a single ensemble member picking up on the evolution of
precipitation today. Further run to run HRRR reliability is next to
zero with the model losing the current features by hour 1, so that
being said very low confidence in PoPs and precip placement tonight.
The overall trend should be drier, but there are indications that
there may be a shallow layer of fzdz with a "warm" -5 C isothermal
inversion with higher RH between 900 and 800 mb. That thin layer
narrows by morning with much drier air moving in aloft. The HRRR
does form an expansive layer of fog by 12Z Sunday over the western
portions of our CWA, so will have to watch for that as its only
covered with patchy wording for now. Hopefully subsequent runs
better capture the moisture profile. Winds should continue to be <
10 kt in most places.
Sunday should be dry and warmer as the area is between systems.
.LONG TERM...(Sunday night through Saturday)
Issued at 303 PM CST Sat Dec 16 2017
This upcoming week will likely have noteworthy weather, including
wind and accumulating snow. Also, the Northland could be heading
into cold snap late this week and into early next week,
potentially bringing the coldest air yet seen this season.
The Northland could flirt and get above freezing Monday. Those
looking forward to clearing our roads of some snow and ice though
may be disappointed. Cloud cover will probably make any melting very
limited. A mid-level trough and passing cold front will bring light
snow Monday afternoon and evening.
Enjoy Monday`s temperatures while they last. It`s downhill from
there. Even colder air begins to rush into the Northland Tuesday. It
looks quite windy. The GFS and NAM12 indicate deep mixing, with at
least 30 to 40 knots within the mixing layer, and potentially up to
50 knots! While it will be difficult to tap into the higher-end of
those wind speeds because of cloud cover limiting the effectiveness
of the mixing, widespread wind gusts of 25 to 35 mph are likely.
It`s safe to say though there could be stray gusts of 40 to 45 mph,
like in the higher terrain of Duluth and the North Shore.
The winds will quickly subside Tuesday night when high pressure
moves through the region. It will be another cold night of lows in
the single digits, if not lower if there is good clearing overnight.
Accumulating snow is likely for the Northland Wednesday and
Wednesday night. The GFS and European still indicate an area of low
pressure will develop in the northern High Plains Wednesday. It will
bring a period of moderate large-scale forcing for ascent over the
Northern Plains and western Great Lakes region later Wednesday into
early Thursday as it moves through the Plains. This low will likely
spread accumulating snow through the Northland Wednesday afternoon
through Wednesday night. Widespread snowfall of 2" to 4" is likely,
but there is potential for more. The greatest snowfall appears most
likely to fall from central Minnesota into northwest Wisconsin, but
it`s possible the band of greatest snowfall could fall farther south
or north. The GFS and European are in reasonable agreement, but the
Canadian has much less snow and much farther south. Placing my
confidence in the GFS and European scenario because of fairly good
consistency with its previous model runs. This system could have a
significant impact on the Wednesday afternoon and evening commute.
Temperatures will likely continue to drop into the weekend.
Temperatures may not get above the single digits Friday and
Saturday. The GFS and European suggest even colder air will be
setting up to move into the Northland early next week. This could
mean a stretch of subzero weather.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 545 PM CST Sat Dec 16 2017
A broad area of MVFR stratus remains draped across the area as of
issuance time, and should continue through at least 15z. Some
deterioration of ceilings height in the 04z-13z time range to IFR
are expected. Visibilities may also deteriorate to as low as IFR,
though confidence is not very high and have only placed them at
the sites most likely to get the fog. A slow improvement to VFR is
expected to begin around 18z, but conditions may deteriorate once
again after 22z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 16 28 19 32 / 0 0 0 30
INL 15 29 19 32 / 20 10 0 50
BRD 17 31 20 35 / 0 0 0 10
HYR 17 29 17 33 / 0 10 0 20
ASX 16 31 19 34 / 0 10 0 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...Wolfe
LONG TERM...Grochocinski
AVIATION...LE
Area Forecast Discussion
National Weather Service Hastings NE
540 PM CST Sat Dec 16 2017
.SHORT TERM...(This evening through Sunday)
Issued at 240 PM CST Sat Dec 16 2017
The warm weather from the past two days will be coming to an end
tonight, with cloudy/cooler conditions forecast for Sunday. Zonal
flow aloft today will give way to a troughy regime with an upper low
in west Texas lifting out across Kansas tonight/early Sunday while a
northern stream shortwave trough sends a cold front south across our
region. That southern low pressure system will bring some
precipitation chances to eastern Kansas, east of our area and have
kept our forecast dry despite the NAM suggesting a light drizzle
potential for our northwest counties. The NAM stands alone with its
light qpf amounts overnight/early Sunday and have kept the forecast
dry.
Low clouds and colder air move in tonight and there could be some
patchy fog along the edge of the stratus. SREF probs and most
guidance do not support dense fog and suggest visibilities may lower
to the 3 to 5 mile range, however the RAP is pretty aggressive
indicating the potential for dense fog across our southern and
eastern zones late tonight into Sunday morning. Wind speeds look to
remain steady enough near 10 mph which should limit dense fog
development and confidence is not high enough to mention fog in
the forecast.
Sunday is shaping up to be a rather cloudy day with noticeably
cooler temperatures trending near seasonal normals. Surface high
pressure settles onto the plains behind the cold front,
reinforcing the cooler airmass. The cloud cover and cooler air
will hold temperatures primarily in the 30s for highs.
.LONG TERM...(Sunday night through Saturday)
Issued at 240 PM CST Sat Dec 16 2017
Heading into next week, we warm back up with temperatures averaging
above normal again Monday through Wednesday, then markedly colder
air arrives by Thursday, just in time for the official start of
winter on December 21st. Thursday will also see the potential for
snowfall, and that frigid airmass which moves in early Thursday looks
to hold through Christmas.
Sunday night, the surface ridge axis departs to the south and a mid
level trough axis exits to the east allowing for rising heights and
a moderating airmass on Monday. Temperatures are expected to recover
nicely, returning to the 50s for highs. A trough translating through
the Upper Midwest region backs in cooler air on Tuesday, dropping
temperatures a few degrees compared to Monday.
Wednesday will feature one more warm but windy day ahead of the
approaching cold frontal boundary. Look for winds to be steady/gusty
from the south with daytime highs in the 50s.
The pattern change takes place Wednesday night and Thursday as an
upper trough dives south from Canada, crossing the northern and
central plains and sending a strong cold front south, bringing an
abrupt end to our above normal temperatures. Current timing of the
front has the boundary entering our NW zones after 06Z Thursday with
the boundary through our cwa by 12Z Thursday. The front will be
noticeable, accompanied by strong north winds and markedly colder
temperatures. H85 temperatures drop a solid 15C to 20C from
Wednesday to Thursday. Temperatures will struggle in the cold air
and high temperatures for the calendar day Thursday will likely be
at midnight, with readings leveling off or falling during the
day. The cold air combined with the strong winds will produce wind
chill readings in the single digits.
Precipitation wise, there is a small chance for light
precipitation (rain/snow) Wednesday night in our southeast zones
along the frontal boundary which is more in line with the latest
GFS. Better chances for snow exist Thursday into Thursday evening
in frontogenetic forcing and upper dynamics as the upper trough
moves through. It`s a fast moving wave, so overall snow amounts
are expected to be light with current models indicating snowfall
of around two inches possible for our northern zones with a half
inch or less in the south, but this will be refined as we get
closer to this event.
The forecast dries out by Friday and remains dry through Saturday
morning, then just small chances for light snow return to our
western zones Saturday afternoon. The cold weather looks to stay
through at least Christmas as a broad trough encompasses the
interior CONUS.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 521 PM CST Sat Dec 16 2017
TAFs could be challenging tonight as the models are trying to
bring in some fog and low ceilings to the TAF sites. Don`t have
high confidence in fog so left it out as the overnight winds will
be around 10kts. Went with MVFR ceilings for the 9z to 17z
period. Some of the models are hinting at some IFR also, but felt
the stronger signal was with the MVFR ceiling. Expect MVFR ceilings
to linger Sunday as mid and high clouds plus the short winter days
will hinder day time heating scattering out the layer.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Fay
LONG TERM...Fay
AVIATION...Beda
Area Forecast Discussion
National Weather Service Marquette MI
1034 PM EST Sat Dec 16 2017
.SHORT TERM...(This evening through Sunday)
Issued at 413 PM EST SAT DEC 16 2017
WV imagery and RAP analysis indicated confluent wnw mid/upper level
flow through nrn Ontario and the nrn Great Lakes. light erly flow
prevailed between high psressure over nrn Ontario and a trough and
front from the cntrl plains through the srn Great Lakes. Vis loop
showed a small clear area over cntrl Upper Michigan but with low/mid
clouds moving in from the west with increasing 280k isentropic lift.
Tonight, lingering east flow off of Lake Michigan with 850 mb temps
around -8C may support some light lake effect pcpn. With marginal
moisture to -10C for ice nuclei, freezing drizzle will also be
possible from near MNM to ESC. Otherwise, veering winds to srly over
Lake Superior will keep any pcpn off shore. Favorable radiational
cooling over the east should allow temps to drop near zero.
Otherwise, clouds will keep temps mainly in the 10 to 15 range.
Sunday, there may be some lingering light pcpn east near Lake
Michigan. Pcpn associated with a shortwav trough moving through nrn
Ontario, will remain north of the cwa. Even with considerable
clouds, WAA will push temps into the mid 20 to around 30.
.LONG TERM...(Sunday night through Saturday)
Issued at 337 PM EST SAT DEC 16 2017
Monday night through Wednesday afternoon: A broad trough sweeping
across southern Canada will brush the CWA Monday night into Tuesday.
Some light snow showers will accompany this trough across mainly the
northern CWA late Monday evening into early Tuesday morning. Colder
air aloft that would be sufficient for LES will lag the main trough
axis, so more prominent LES will hold off until a secondary surface
trough crosses the west Tuesday afternoon and the east Tuesday
evening. Though LES will be generally weak early Tuesday, gusty
W/WNW winds to 45mph across mainly the Keweenaw Peninsula combined
with a loose snowpack may create intermittent whiteout conditions
Tuesday into Tuesday evening. The same will likely hold true near
Lake Superior east of Munising Tuesday afternoon and evening. A
period of moderate lake effect snow for the W to NW wind snow belts
is then expected Tuesday night before diminishing from west to east
on Wednesday.
Wednesday night through Saturday: Though there remains a lot of
uncertainty in the forecast during the second half of the week, the
main message is that more active weather with accumulating snow will
affect at least portions of the western Great Lakes Wednesday night
through Friday.
A potent mid-level trough moving onto the NW CONUS Tuesday night
will become stretched across the central CONUS by Thursday
afternoon. The extreme positive tilt with the northern portions of
this trough complicate the forecast across the Upper Great Lakes by
Wednesday night. Somewhat disorganized lee cyclogenesis in the
Plains will spread a shield of WAA precip across the region
Wednesday evening into Thursday. Guidance has been quite
inconsistent on the placement of the generally narrow swath of
precip, with the GFS switching from the northern-most solution
yesterday to a much more open southern track with today`s 12Z
guidance. The GEFS and other long-range guidance only increase
uncertainty with a wide distribution of solutions. With that said,
there is a relatively high chance of at least some accumulating snow
across the CWA with this system Wednesday night into Thursday.
By Friday and Saturday, model disagreements grow substantially, with
some solutions suggesting chances of an organized system bringing
accumulating snow across the region as the upper trough receives a
re-enforcing shot of energy from the north. Again, with significant
uncertainty this far out, those with holiday travel plans should
continue to monitor forecast updates.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1034 PM EST SAT DEC 16 2017
MVFR conditions will continue for most of this forecast period at
all sites as srly low level flow as increasing moisture advection
develops.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 413 PM EST SAT DEC 16 2017
Southwesterly winds will increase late Monday to 20 to 30 knots
before veering to northwesterly gales to 35-45 knots late Mon night
through Tue night. With increasing wave heights, freezing spray is
possible Tuesday night into Wednesday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Kluber
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service Tallahassee FL
823 PM EST Sat Dec 16 2017
.UPDATE...
No significant changes were made to tonight`s forecast as high
clouds will gradually increase overnight; lows will be in the 40s
inland with lower 50s near the Gulf Coast. Chances of rain
showers have been slightly increased/expanded tomorrow throughout
the day as a warm front and increasing deep layer moisture move
northward into our area. PWAT values increasing to around 1.5" by
the afternoon and isentropic lift along with the warm front
should support the development of isolated/scattered showers
during this time; some recent runs of the HRRR have been more
aggressive with an initial wave of scattered showers near the Gulf
Coast during the late morning as well. As a result, increased
PoPs into the 20-30% range across much of our area tomorrow. A
slight downward adjustment was made to forecast highs on Sunday as
well due to increased cloud cover and rain chances, although most
areas should still see highs around 70 as southerly flow
increases behind the warm front.
&&
.PREV DISCUSSION [626 PM EST]...
.NEAR TERM [Through Tonight]...
A shortwave near the Texas Big Bend this afternoon will lift
northeastward into the Central Plains overnight. At the surface, a
cold front will advance into the Lower Mississippi Valley with rain
preceding it. However, the rain will hold off for our area until
after daybreak. Look for increasing clouds through the period with
lows in the lower to mid 40s.
.SHORT TERM [Sunday Through Monday Night]...
Moist isentropic ascent will begin over the western portions of
the forecast area Sunday morning with increasing chances of rain
by midday along a frontal zone extending from coastal LA into West
Central Georgia. Model guidance suggests the lift will maximize
by 18z Sunday and then diminish into the evening.
By Sunday evening, another batch of forced ascent will lead to
more widespread shower activity across the Central Gulf Coast
States. With the best lift remaining focused just west of our
region, will maintain a tight W-E PoP gradient across the forecast
area. The big difference to the forecast by Sunday night will be
the much warmer than normal overnight lows in the upper 50s to low
60s.
On Monday, the frontal zone will continue lifting north of the
region in response to ridging building east of the Florida
Peninsula. Rain chances will be decreasing south to north
throughout the daytime hours with rain chances nearing zero by the
overnight hours. Temperatures will be noticeably warmer and the
airmass more humid when compared to the previous weeks.
.LONG TERM [Tuesday Through Saturday]...
The period begins with a large ridge aloft centered over the
Florida Straits and an approaching trough in the southern stream
moving through Texas. Though Tuesday is likely to be dry and warm
with moist southerly flow ahead of the approaching system, rain
chances will increase considerably by Wednesday as the upper
disturbance moves quickly into the Mid South. Though this wave
will weaken with time moving through the Tennessee Valley,
sufficient height falls (around 60m) across the western portion of
the forecast area along with other favorable severe parameters
(0-6 km shear of 40-45kt and non-zero surface based instability)
would suggest at least some threat for severe weather on
Wednesday. It should be noted, however, that with an extensive
period of offshore flow and cooler than normal temperatures, the
nearshore shelf waters are quite cool, especially from Apalachicola
eastward, and this could have a stabilizing effect on the severe
potential across Srn GA and into the Florida Big Bend.
After the system on Wednesday, the region will be between systems
heading into the weekend. With the pattern supporting above normal
temperatures and a humid airmass, there is potential, particularly
across the western portion of the region for scattered showers
beginning Friday and continuing through the end of the period.
Unseasonably warm temperatures in the mid 70s during the day and
mid to upper 50s at night will be common by the end of the long
term period.
.AVIATION [Through 00Z Monday]...
Cloud cover will gradually increase overnight through Sunday
morning and afternoon, but VFR conditions are likely to prevail
through the remainder of the period. Only high clouds are expected
overnight, with mid-level clouds expected to increase Sunday
morning and afternoon. There will also be slight chances of
showers on Sunday late morning and afternoon, but chances are too
low at this time to include in the TAFs.
.MARINE...
Winds will shift to a more southerly component by Sunday afternoon
and briefly increase to near 15 knots. A period of lighter winds
is expected by Monday night. A storm system will approach the
marine area on Wednesday, increasing winds to near advisory
levels. Winds will then decrease in the wake of a frontal system
by Thursday and remain low into the start of the weekend.
.FIRE WEATHER...
Increasing moisture will result in high RH values from tonight
through the next several days. As a result, no fire weather concerns
are anticipated.
.HYDROLOGY...
Decent rain chances are expected on Monday and then again on
Wednesday across the region, where totals after both events could
be in the 1-2 inch range. While flooding is not expected with
either event, this rainfall will help improve the ongoing dry
conditions across the region.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 45 70 61 75 61 / 0 20 30 20 10
Panama City 51 69 65 74 63 / 0 30 50 20 10
Dothan 44 68 62 73 60 / 0 30 50 50 30
Albany 42 68 59 73 59 / 0 20 40 50 30
Valdosta 42 71 59 76 60 / 0 10 20 30 10
Cross City 44 73 57 78 58 / 0 10 10 10 0
Apalachicola 52 69 63 74 62 / 0 30 40 10 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...Lahr
NEAR TERM...Barry
SHORT TERM...Godsey
LONG TERM...Godsey
AVIATION...Lahr
MARINE...Godsey
FIRE WEATHER...Lahr
HYDROLOGY...Godsey