Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/01/16
Area Forecast Discussion
National Weather Service Binghamton NY
918 PM EST Wed Nov 30 2016
.SYNOPSIS...
Rain will continue across the region tonight before drying out
during the day Thursday. Temperatures will be cooler Thursday with
a slow downward trend into the weekend. Rain showers will mix with
and change to snow later Friday and eventually become mostly snow
later in the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
915 PM Update...
Current forecast in good shape just minor adjustments to the
overnight temperatures and pops. Rain has spread back across
northeast Pennsylvania and much of central New York this evening
as a mid level wave moves through the region in advance of a surface
cold front which is moving through extreme western New York at
this time. This boundary will cross the area from around 11pm-3am
and bring the last shot of widespread showers. Currently along
this boundary in western New York some of the convection has
been associated with a few lightning strikes. This is due to mid
level instability and frontal forcing. As this boundary crosses
the region will continue to mention a rumble of thunder with
slight chance pops for thunder.
previous disc...
Main concerns in the near term remain centered around the ongoing
persistent rain over ne PA and se NY this afternoon into the
evening...with a secondary wave of convection expected to develop
over the Lake Erie/PA/NY/OH area early this evening and move east
through central NY/ne PA through the early overnight hours.
Conditions will be cooler and slightly drier on Thursday with
gusty west winds.
A robust supply of deep layer moisture from the south continues to
stream nwd into PA/NY this afternoon and interact with strong large-
scale lift as an upper trough approaches from the west to produce
widespread rain across much of ern PA and sern NY into New England.
This area of rain to the east will continue to slowly drift ewd this
evening...producing an additional 0.5 to 1 inch of rain from the
Poconos to the srn Catskills.
Areas further to the west...including the Finger Lakes...have missed
out once again on the significant rainfall today. However, there
may be another chance this evening and tonight to make up for
that. Latest visible satellite imagery shows some scattering of
clouds over far wrn NY...and the RAP meso-analysis indicates weak
elevated instability and steepening mid level lapse rates around
the Buffalo area. A cold front currently moving through MI/ern OH
will eventually catch up with this area of weak instability and
trigger convection into central NY and portions of n-central PA.
This area of convection will likely combine with the continuous
supply of moisture from the south for widespread rain
showers...and even a few embedded weak thunderstorms through the
evening hours. May see an additional 0.25 to 0.75 inch of rain
tonight over much of cntrl NY.
As the cold front advances ewd late tonight and Thur morning the
deep layer moisture will decrease markedly and mainly leave behind a
layer of low stratus in its wake. Mid level air will continue to
cool slowly through the day Thursday and combine with warm Lakes
Erie and Ontario...and relatively warm near-sfc temps to produce
downwind convective rain showers. 850mb temps around -3 to -5 deg C
will not be cold enough to generate significant precip...and
trajectories will be roughly 260 to 280 deg most of the day which
would tend more toward the Tug Hill area and wrn NY, possibly into
the Finger Lakes.
Temperatures tonight will fall only into the upper 30 to around
40...and have a hard time reaching much above 45 Thursday
afternoon as the cold air funnels in behind the cold front.
Winds will also continue to be a factor tonight with sustained south
winds around 10 to 20 mph this evening...shifting to the west by
Thur morning increasing to 20 mph with gust up to 30 mph Thur
afternoon.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
245 EST Update...
By Thursday night surface winds will become breezy out of the
southwest as the upper lvl low continues to stay parked over
western Quebec with near zonal flow prevailing over the region.
This pattern will continue through the night, advecting cold air
into the region, which will result in lake enhanced/orographic
lift showers over the region. The airmass will remain warm through
midnight. Precip will fall in the form as rain, but after
midnight the atmos should cool down enough that snow growth may be
possible within the higher terrain. The low-lvl mean flow across
the lakes will remain around 280 through 12Z Friday, thus, expect
more so a single band orientation, over the southern Tug Hill
Plateau. During the day on friday expect the mean flow to meander,
and the band the shift southward during the morning hours then
shift northward again early Friday afternoon.
A shortwave is expected to drop south over the region early Friday
evening, which will bring a chance for showers area wide across the
region. This shortwave Friday evening will allow for an even colder
airmass to funnel into the region. Precip type will be highly
dependent on sfc temps. Temps at or above 36 may see rain, while
temps that fall below this mark may see a mix of rain/snow or
completely transition over to snow. This pattern will continue
through Saturday, as CAA will be significant enough for lake effect
showers to continue across the region. Again, precip type will be
highly dependent sfc temp as well as elevation.
Temps will rise into the uppr 30s to low 40s Friday and Sat, and
fall into the low 30s during the overnight periods.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
245 PM EST Update...
Little change to the extended forecast. Deep troughing over the
western CONUS is expected from Saturday evening through Wednesday
allowing multiple waves to move across the eastern CONUS creating a
chances for precip over the region for much of the period. Scattered
rain/snow showers will prevail starting Saturday night through mid
week as conditions are favorable. A brief period of high pressure
will build over the northeast during the mid-week but will
quickly diminish as the next system will pushes into the region.
The next system may arrive as early as Tuesday night. Confidence
is low on the timing on the next system, we may be dry for a
couple of days, but confidence increases with pops as we head
towards the weekend.
Temps during the extended forecast will be at or slightly above the
seasonal average.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Strong moist southerly flow will continue for the beginning of the
TAF period in advance of a cold front which will move through
between 03z and 08z from west to east across our terminals in
central NY and northeast PA. In advance of the front there were
rain showers and mainly MVFR ceilings with patchy areas of VFR
conditions. As the front nears and crosses terminals we expect a
period of IFR in heavy rain showers mainly from visibility
restrictions. However the usual terminals KBGM, KRME and KITH
will see more widespread IFR conditions between 04z and 09z at
KITH/KRME and from 05z to 14z at KBGM. Once the front passes by, a
westerly flow of cooler and drier air will set up and ceilings
will come up to VFR all terminals with KSYR, KELM and KAVP seeing
VFR around 08z-09z and lasting through 00z Friday. KBGM/KRME will
see VFR conditions last by 19z and KITH by 16z.
Winds will be southerly until 07z-09z after frontal passage with
low-level wind shear at KSYR and KAVP for small periods overnight.
OUTLOOK...
Thursday evening...Restrictions possible in occasional showers,
mainly at KSYR and KRME. Other terminal sites will likely see VFR
conditions.
Friday through Monday...Occasional restrictions in scattered
rain/snow showers, especially across central NY terminals.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...BJT
NEAR TERM...BJT/RRM
SHORT TERM...KAH
LONG TERM...KAH
AVIATION...DJN
Area Forecast Discussion
National Weather Service Buffalo NY
919 PM EST Wed Nov 30 2016
.SYNOPSIS...
A cold front will advance across the region tonight, bringing rain
showers and eroding the very warm airmass that is in place. A colder
airmass will then follow, Thursday through the end of the week, with
lake effect rain showers east of the lakes Thursday that will mix
with snow Thursday night and through the start of the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
A cold front extending from low pressure centered near Lake Huron
will race across Western New York this evening. At 9 p.m. this
front was located near Buffalo, with a solid line of showers
along this boundary. This line appears quite convective, with a
few lightning strikes in the heavier showers in this line.
Lightning strikes have been diminishing over the past hour, and
this trend should continue this evening with scattered
thunderstorms becoming more isolated in nature.
Otherwise this line will quickly move from west to east across
the cwa tonight. Expect a couple hours of briefly heavy rain as
this front moves through, followed by post-frontal wind gusts to
around 30 mph. Rainfall amounts should run between a quarter and
half an inch, with locally higher amounts.
In terms of model guidance, the HRRR has a good handle on this
front and is favored given its hourly resolution which should best
capture the abrupt change in conditions with its passage. Pre-
frontal temperatures are still in the 50s, with a quick 10 degree
drop with the frontal passage.
After this line of showers/cold front passes across the region
tonight, a much colder airmass will build southeastward across the
Lower Great Lakes. Temperatures at 850 hPa will lower to around
-4C on Thursday which should bring ample instability over a +8 to
+10C lake waters to produce a band of lake effect precipitation.
The lower levels of the atmosphere, and surface temperatures will
remain too warm for snow, such that just plain rain will fall from
these lake plumes later tonight and tomorrow. An initial 240 to 250
wind flow will bring these plumes to around Buffalo (Lake
Erie)/Watertown (Lake Ontario) before settling ever so slightly
southward later Thursday. The only exception is across higher
terrain in the Western Southern Tier where a few wet snowflakes
may mix in on Thursday.
Temperature will remain mild this evening ahead of the cold front
with falling temperatures the second half of the night dropping down
into the lower to mid 40s. Under cold air advection aloft highs
tomorrow will not be much warmer than their morning values, with
highs only rebounding a few degrees. This cold air advection will
also create brisk winds tomorrow. Southwest winds will howl near the
lake shores, and especially the northeaster lake shores, with gusts
up to 40 mph. Inland southwest wind gusts will be lower, generally
25 to 35 mph.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Mid level closed low will cross Quebec and morph into an open wave
as it crosses into New England by Friday, eventually re-developing
over the Canadian Maritimes as energy transfers to the coast by
the weekend. There will be a series of minor shortwaves and their
associated surface troughs wrapping into western New York into the
first part of the weekend, resulting in periods of deeper
moisture and lake driven precipitation. Temperatures aloft will
gradually turn colder over this time with 850 mb temperatures
starting the period from -4/-5c, down to -7/-8c by Saturday. Low
level flow starts out westerly, slowly veering to northwest by
Saturday. This seasonably cool and moist cyclonic flow will
providing a favorable background for lake enhanced/effect
precipitation. Outside of the lake driven areas, occasional weak
ascent from passing subtle shortwaves will produce scattered light
showers, with the better coverage of these synoptic showers across
the North Country in closer proximity to better forcing and deeper
moisture.
Off Lake Erie...
The cooling boundary layer will allow for some wet snow to mix in
across higher terrain Thursday night into Friday, with a probable
change to all wet snow at times for the higher terrain. Expect a
slushy 1-2 inches of accumulation later Thursday night into Friday
morning across the high terrain of the Boston Hills and western
Wyoming County, and the hills of central and northern Chautauqua and
Cattaraugus counties.
Friday night and Saturday, the boundary layer will continue to cool
as boundary layer turn more northwest. This will push the lake
effect precipitation farther south into the Southern Tier. There
may be some additional minor accumulations across higher elevations.
Lake effect precipitation will then slowly diminish during the day
Saturday as a mid level ridge and somewhat drier air begin to build
into the Lower Great Lakes.
Off Lake Ontario...
The boundary layer will undergo modest cooling Thursday night which
will allow wet snow to mix in across the higher terrain of the Tug
Hill and western Adirondacks, with a probable change to all wet snow
late Thursday night through Friday across the highest elevations
where a 1-3 inch slushy accumulation is possible.
Friday night, the boundary layer will continue to cool as boundary
layer turn more northwest. This will push the lake effect
precipitation south and onshore from the Rochester area eastward
into the Finger Lakes. There may be some additional minor
accumulations across higher elevations.
On Saturday northwest flow will continue, with a spray of weak lake
effect showers southeast of the lake from near Rochester to Oswego
County.
Saturday night and Sunday, cool west northwest flow will remain in
place, supporting a few scattered rain and wet snow showers, and
some limited lake effect southeast of the Lakes. Temperatures will
be seasonable, with highs in the lower 40s at lower elevations and
mid to upper 30s across higher terrain.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Model guidance begins to diverge by early next week, with
significant run to run differences noted in both the GFS and ECMWF
over the past few days. A weak trough is forecast to move northeast
across the area Sunday night and early Monday with a few wet snow
and rain showers possible from a combination of weak ascent from the
trough and a broad warm advection regime.
Monday night and Tuesday both the GFS and ECMWF show high pressure
back into the Ohio Valley and Lower Great Lakes. The mid continental
trough ejects a wave into the upper ridge, with strong southerly
warm advection, the ECMWF much more potent than GFS, but went with
withering PoPs for Tuesday and Wednesday and just chance PoPs, at
that. Note that the models have seemingly stretched the arrival
times of the next strong cold front and pattern change to wintry
conditions into the mid/end of the week.
Regardless of the synoptic details, the overall pattern suggests
a return to slightly above normal temperatures for Tuesday and
Wednesday, but an eventual arrival of wintry weather by the end
of the week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
The primary forecast factor tonight will be the passage of a cold
front. At 02Z this front was between IAG/BUF and it will continue
to move quickly east late this evening. A solid line of moderate
to heavy rain showers extends along this boundary, with these
expected to move eastward with the front. There still are some
isolated thunderstorms embedded in this line, but these have
trended down over the past hour, with any impact to a terminal
location expected to be brief. IFR/MVFR conditions will accompany
this line of showers, with a modest improvement to VFR/MVFR
conditions expected behind the front when winds pick up and help
mix low moisture out.
Thursday will be mostly cloudy, with lower (MVFR) cigs mainly
isolated to higher terrain or in lake effect rain showers. The
southwest flow will make these most likely at BUF and ART.
Outlook...
Thursday night and Friday...MVFR/IFR with lake effect rain showers
shifting southward and becoming mixed with snow showers.
Saturday and Sunday...Mainly VFR with areas of MVFR/IFR and
rain/snow showers east of the lakes.
Monday...IFR in chance of snow showers, becoming MVFR/VFR as
precipitation transitions to rain showers.
&&
.MARINE...
An area of low pressure will pass just to the north of Lake
Ontario tonight and tomorrow, while swinging a cold front across
the Eastern Great Lakes tonight. There may be a few thunderstorms
with this frontal passage.
Behind the cold front expect westerly winds to increase, nearing 30
knots on the lake late tonight and through the day tomorrow. These
winds will gradually diminish Friday and Friday night, but based
on the lastest forecast we have extended the small craft headlines
on the lakes as outlined below. Gusty winds will also rush across
the rivers, with no changes to the current small craft headlines.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 6 AM EST Saturday for LEZ040-041.
Small Craft Advisory until 4 AM EST Friday for LEZ020.
Small Craft Advisory until 1 AM EST Friday for LOZ030.
Small Craft Advisory until 6 AM EST Saturday for LOZ043.
Small Craft Advisory until 6 PM EST Friday for LOZ042.
Small Craft Advisory until 6 AM EST Saturday for LOZ044-
045.
Small Craft Advisory from 4 AM Thursday to 1 AM EST
Friday for SLZ022-024.
&&
$$
SYNOPSIS...THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...HITCHCOCK/WCH
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
Area Forecast Discussion
National Weather Service Grand Rapids MI
1020 PM EST Wed Nov 30 2016
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 325 PM EST Wed Nov 30 2016
An upper level trough of low pressure will bring cool and
unsettled weather tonight through late this week with extensive
cloud cover and intermittent rain showers. Some wet snow flakes
will mix in late tonight into Thursday morning as well but
there will be no snow accumulations. High pressure will briefly bring
dry weather for Saturday before another system moves in to bring
potential for mixed rain and snow showers for Sunday.
&&
.UPDATE...
Issued at 1020 PM EST Wed Nov 30 2016
Recent mPING report of a rain/sleet mix around Holland and a few
similar reports were noted earlier around Chicago. This is not
surprising given the convective nature of the precipitation. Based
on radar trends and short range guidance, have raised
precipitation chances to categorical overnight. Expect a
rain/snow mix to develop around or shortly after midnight
generally east of US-131, which is east beyond the influence of
the lake modified plume. Latest RAP guidance suggests that Wet
Bulb Zero (WBZ) height should be dropping below 1500 ft AGL around
this time, which is a good proxy for seeing snow. Dual Pol radar
products already suggest the WBZ is below 2000 ft, so the mix this
should not be too much longer in taking shape. Accumulations
should be negligible due to warm surface temperatures overnight.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 325 PM EST Wed Nov 30 2016
Primary short term fcst challenges involve determining
probabilities for showers and to assess potential for pcpn type
issues mainly for late tonight into Thursday. The upper
level trough will bring cool and unsettled weather tonight
through Thursday. Showers will develop this evening as deeper
moisture moves in and showers will increase in coverage overnight.
Brisk southwest flow caa tonight will cause pcpn to become mixed
with some wet snow very late tonight through the early to mid morning
hours Thursday as wbz heights and low level critical thickness values
lower and deeper moisture through the dgz moves in. However only a
couple tenths of an inch of snow will fall mainly east of US-131 and
there will be no snow accumulation overnight. Pcpn type will remain
mainly all liquid form west of 131 due to the modifying affect of
Lake MI.
Seasonably cool and unsettled wx will continue through the day
Thursday with scattered light rain showers. Pcpn type Thursday
will be predominantly liquid form although a few wet snow flakes
may mix in mainly early in the day.
Extensive cloud cover and scattered light rain showers will linger
Thursday night through Friday. The relatively best chc for a few
showers will continue to be near to west of US-131. 12z guidance
consensus time height rh/temp progs indicate an unsaturated dgz
Thursday night through Friday so light rain showers/drizzle will
be the predominant pcpn type.
.LONG TERM...(Saturday through Wednesday)
Issued at 325 PM EST Wed Nov 30 2016
Followed the GFS for guidance in the long term as it has had much
better consistency the last few days. The ECMWF has had issues
handling southern stream energy, namely the upper cut off low moving
across northern Mexico. Temperatures through the long term look to
undergo a slow moderating trend through the period and end up a bit
above normal as we head into next week.
The long term period begins on Saturday with some light lake
generated precipitation ongoing. The moisture depth decreases
quickly though, so precipitashortly after midnighttion should
come to an end as we move through the day. Expecting a dry
Saturday night with ridging moving through the area.
Sunday a northern stream shortwave will move through the area
bringing some rain and snow to the area. Surface temperatures as
well as 850mb temps would indicate a rain and snow mix with
potentially some light wet snow accumulations possible. Would not
expect more than an inch or so at best.
Ridging takes hold for Sunday night into Monday night with mainly
dry weather expected. The GFS then has a warm air advection event
for Tuesday into Tuesday night when rain will likely be the
predominant precip form.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 704 PM EST Wed Nov 30 2016
Little change to the previous forecast. Expect precipitation to
increase and ceilings to lower below 2000 ft AGL at all terminals
before 03Z and last well after 12Z. There is a low probability
for IFR conditions, which most likely would take the form of brief
CIGS just below 1000 ft AGL in the 09-13Z timeframe.
&&
.MARINE...
Issued at 325 PM EST Wed Nov 30 2016
A small craft advisory remains in effect from this evening through
early Friday morning. Southwest winds will ramp up to 15 to 25 kts
tonight and cause wave heights to build to 4 to 7 feet. West winds
of 15 to 25 kts will cause wave heights to remain up at around 4
to 7 feet through Thursday as well.
&&
.HYDROLOGY...
Issued at 200 PM EST Wed Nov 30 2016
Sycamore Creek at Holt has crested a few inches above bankfull and
is now receding. Maple River at Maple Rapids continues its slow
rise toward bankfull. Only light lake enhanced precipitation is
expected this week, but it will not affect river levels. There
will be chances for more substantial precipitation next week.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 4 AM EST Friday for LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...Duke
AVIATION...TJT
HYDROLOGY...CAS
MARINE...Laurens
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1009 PM EST Wed Nov 30 2016
.SYNOPSIS...
Low pressure will track from the Great Lakes into Quebec tonight
as a secondary low develops over the mid Atlantic region. This
secondary low will track along the New england coast late tonight
and Thursday drawing colder air into the mountains and adjacent
foothills, changing a snow and rain mix there over to wet snow.
Precipitation will taper off on Thursday as the low exits into the
maritimes. Somewhat cooler and drier air will arrive late Thursday
and Friday with temperatures cooling as we move into the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
1008 PM Update: Rain Snow line setting up for the time being over
southern Oxford county reaching east to along the
Franklin/Androscoggin/Kennebec county border. Have adjusted
weather and snow total /as well as temperatures/ slightly to match
these observations. Do expect a warming trend to commence over the
next 1-2 hours...but as mentioned earlier...some light accums
possible north of this line.
853 PM Update: Based on spotter reports that corroborate GYX 88D
correlation coefficient values across southern Oxford/Franklin
counties...have nudged initial rain/snow line a bit further south.
This lines up with about a +1C max wetbulb aloft from the RAP.
Only minor adjustments in snowfall amounts were necessary. The
profile in these spots is expected to warm over the next 2-3
hours...but a quick inch /2?/ of snow is not out of the question.
No other changes at this time.
742 PM Update: Forecast continues to generally be in very good
shape and have only made minor adjustments based on latest
observations including a glance at the 00Z GYX RAOB...which shows
a bit too much warm air for SN at GYX...but is well in line with
near term RAP forecasts. Correlation coefficient from the GYX 88D
reveals a melting layer around 4500 ft AGL...with local lowerings
of this in the heavier precipitation elements. Thus...feel that
ptype expectation is in good shape with no significant changes
necessary. Could see some sleet mix in with the rain as far south
as southern Oxford/Franklin counties...but rain will dominate even
in these spots through the evening.
547 PM Update: Going forecast in good shape. Input latest
observations and adjusted PoPs to slow northward progression of
steadier precipitation just a tad based on latest regional radar
composite. No significant changes to ptype thinking at this
juncture. Will reassess after 00Z RAOB comes in over the next 1-2
hours.
Previous discussion below...
At 19z...a 1028 millibar high was centered over eastern Canada
and was nosing southward into eastern New England. A complex area
of low pressure was over the Great Lakes with a wavy frontal
boundary extending through the DELMARVA region. NWS doppler radar
mosaic showed an extensive area of precipitation along and to the
south of the frontal system. Colder and drier air was draining
south and west from northern Maine with the canadian high and will
set the stage for wintry precipitation across portions of the
mountains and foothills as precipitation spreads northward and the
atmospheric column cools to at or below 0c. In additional...the
developing coastal low will also help to draw even cooler air
southward into this area late tonight and Thursday morning as it
races northeast along or just offshore. There will be large
variations in snow and sleet amounts as we deal with mixing as
well as elevation issues. Outside of the mountains and
foothills...mainly a cold rain event is expected tonight.
&&
.SHORT TERM /THURSDAY NIGHT/...
Precipitation will taper from southwest to northeast on Thursday
following the passage of the coastal low and occluded front.
Precipitation will linger the longest along the International
border as well as eastern zones before ending during the
afternoon. Some drier air will work into southern New Hampshire
and southwest coastal Maine behind the departing low...with
partial sunshine and westerly flow allowing temperatures to warm
into the lower 50s. Highs elsewhere mainly in the 40s...with 30s
across the northern mountains.
Breezy and cold Thursday night with mainly clear skies for
southern New Hampshire and much of the coastal plain in downslope
flow. Elsewhere...cyclonic flow and upslope with a few mainly
mountain snow showers. Lows will be in the 30s.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
By daytime Friday cold air has already begun shifting into the
Great Lakes region and New England. Additional snow showers are
likely over the mountains with rain showers less likely as a
surface trough moving offshore. Reinforcing cold air arrives
Friday night with 850mb temperatures dropping to near -10 degrees
C. Additional snow accumulations are likely Saturday on northward
facing slopes as WNW winds increase aloft and at the surface.
Winds will be strong and gusty from the NW on Saturday. This will
help clouds clear out over the coastal plain gradually. Sunday
through Tuesday cold high pressure from Canada builds in.
Temperatures early in the work week will be around the mid
20s/lower 30s north to upper 30s/near 40 for highs. Overnight it
looks like there will be at least a few chilly nights: Saturday,
Sunday, and Monday with readings in the tens and teens across the
mountains and 20s elsewhere. There will be a gradual warm up for
mid week for southern NH and on the coast with warm air advection
trying to nudge in ahead of the next wave arriving from the
central CONUS. However...during this time cold air damming
sharpens as it did earlier this week and isentropic lift
increases over the cold dome at the surface. This may bring mixed
precipitation and dense fog/freezing fog conditions to areas away
from the coast.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term /Through Thursday night/...
Summary: Low pressure will develop along an arriving front tonight
and move east of the region on Thursday with another round of rain
and poor flying conditions expected...with improvement by late
morning Thursday and continuing through Thursday night as low
pressure pulls away to the east.
Restrictions: MVFR/IFR conditions will deteriorate to LIFR/IFR in
rain overnight. Improvement back to VFR is expected behind
departing low pressure on Thursday afternoon with VFR generally
expected through Thursday night outside of some possible MVFR cigs
and light snow showers at HIE.
Winds: Northeasterly winds 10kts /14g22kts at the coast/ for the
overnight will shift west/northwesterly during the morning
Thursday and continue through the afternoon...strengthening
to 10g18kts. Thursday night these winds will diminish below 10kts.
LLWS: Southeasterly winds in the 1-2kft layer increase to 35-45kts
for the overnight with shear ending near or just after daybreak
Thursday.
Long Term...RKD, AUG, and PWM will see a chance of -SHRA through
mainly Friday. HIE may continue to experience -SHSN through
Saturday. NW winds will be gusty especially Saturday afternoon
into Sunday morning. VFR returns to all TAF sites Sunday with
additional rain and snow showers moving in from the SW late Sunday
into Monday.
&&
.MARINE...
Short Term /Through Thursday night/...Winds and seas build
quickly ahead of the coastal low overnight and it`s likely we`ll
see a period of Gales over our eastern waters including Penobscot
Bay late tonight and Thursday morning immediately ahead of the
coastal low. behind it...westerly flow should reach small craft.
Long Term...Winds will most likely reach SCA criteria on the outer
waters and bays Saturday afternoon into early Sunday.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 1 PM EST Thursday for MEZ008-013-
014.
Winter Storm Warning until 3 PM EST Thursday for MEZ009.
NH...None.
MARINE...Small Craft Advisory until 11 AM EST Thursday for ANZ153-154.
Gale Warning until 11 AM EST Thursday for ANZ150>152.
&&
$$
SYNOPSIS...
NEAR TERM...Arnott
SHORT TERM...
LONG TERM...
AVIATION...Arnott/Hanes
MARINE...
Area Forecast Discussion
National Weather Service Wilmington NC
915 PM EST Wed Nov 30 2016
.SYNOPSIS...
Mild and moist south to southwest winds will continue through
tonight as a strong cold front approaches the Carolinas from
the west. The front will move off the Carolina Coasts and
offshore during Thursday morning, basically around daybreak.
Cooler and drier Canadian high pressure will infiltrate the area
during Thursday through Sunday. Areas of low pressure will
affect the area late Sunday thru the first half of next week
with clouds and increasing rain chances.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 830 PM Wednesday...After the line of convection pushed
across the Appalachians, a decrease with intensity was noted as
well as some pcpn areal coverage. The activity is now pushing
across the I-95 corridor and has now stabilized with respect to
intensity. Meaning, it`s basically light shra with embedded
moderate shra. Occasionally, will see a reflectivity more in the
form of a convective cell, but they have become less and less of
an occurrence as this pcpn as a whole moves eastward. The
activity will become somewhat more diffuse in coverage when it
reaches the ILM CWA Coast. This due to question instability and
the main dynamics aloft, ie. 300 mb wind jet streak further
staying further west and north of the ILM CWA as it moves off to
the NE. Thus, the area does not directly experience the RR
quadrant of this upper jet along with the associated UVVS.
Have made adjustments to the POPs and QPF thru daytime Thu
morning in response to this area of pcpn tracking to the east
with individual elements accelerating to the northeast. Have
indicated 3 hr QPF blocks to better gage the occurrence of pcpn
amounts.
Very little tweaking of temps and dewpoints needed at this time
with expected CFP followed by CAA and drier air basically
occurring late this period, but mainly during the short term
period following.
Previous....................................................
As of 300 PM Wednesday...Strong southwesterly winds aloft
continue ahead of a large upper level-low that is still centered
over the northern Mississippi River valley of Minnesota and
Wisconsin. Water vapor imagery is showing the strong jet
rotating up the southeast side of the low with speed nearing 110
knots at 500 mb over the lower Mississippi River valley.
Most of the showers that formed on the convergence boundary this
morning have shifted off the coast with a scattered showers
developing back to the west over Columbus and Bladen counties. The
showers are expected to be isolated to scattered through the early
evening. The 17 UTC HRRR shows the convective line that is moving
across Georgia at this time will approach the western counties
around 7 PM, and will weaken as it moves across the county warning
area through the night. Also, the 12 UTC NAM, GFS and ECMWF all
show this strong line weakening as it moves across the region. The
chances for significant precipitation in our area are not looking as
good with this model cycle. The models are indicating the chances
of precipitation will extend to just after 12 UTC for southeast
South Carolina but earlier for the areas to the west.
The lows overnight will drop into the middle 50s west of Interstate
95 and lower 60s at the coast.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...This period will see the remainder of any
showers exiting the southeast North Carolina coast with high
pressure building in behind the cold front. This high pressure is
expected to continue through Friday night.
High temperatures are expect to only be in the upper 60s on Thursday
and with cold air advection behind the cold front highs on Friday
will only be around 60. Low temperatures on Thursday night will fall
into the upper 30s well inland to the lower to middle 40s at the
immediate coast line. On Friday night temperatures will drop into
the middle 30s well inland and 40 to 42 at the beaches.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 PM Wednesday...A deep cutoff upper low across the
Baja peninsula will eject out into the southern stream flow
early next week, bringing rain chances to the Carolinas. However
the timing of this remains uncertain owing to extremely large
model differences between the slower GFS and faster ECMWF.
Forecasters at WPC have access to a great deal of data we don`t
at the local NWS level, and noted in their extended discussion
that the ECMWF ensembles resemble the GFS operational run and
its ensembles much more than they do the ECMWF operational run.
For this reason, we favor a GFS-centric forecast for the
extended period.
Surface high pressure and a low-amplitude upper level ridge
should keep Saturday dry. However by Sunday moisture should
begin increasing in advance of the big upper system ejecting out
of Mexico. While even the fast GFS doesn`t bring the trough to
our longitude until Tuesday, increasing flow of Gulf moisture in
the mid-levels should bring clouds and perhaps a little light
rain to the area Sunday afternoon or Sunday night. Rain chances
then develop again on Tuesday when I`ve increased rain chances
to 40-50 percent.
A northern stream trough which is shown in both the GFS and
ECMWF should roll east out of the Rockies during the middle of
next week and could begin to spread another risk of rain into
the area by late Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 00Z...Persistent fog along the coastal terminals has broken up
leaving IFR ceilings with low stratus. A cold front will track
across the TAF sites from west to east tonight. This should produce
a line of showers with gusty SW to W winds. Have not included
thunderstorms in TAFs due to timing of frontal passage, but expect
rapidly moving showers with some heavier rain and stronger winds
possible just ahead of and along the front from 02-06z inland and
05-09z along the coast. Post fropa expect VFR with westerly winds
through end of TAF period.
Extended outlook...Expect VFR. Expect clouds and pcp back in
forecast by end of period with some MVFR/IFR conditions possible by
Monday.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 830 PM Wednesday...Winds over the waters have veered
slightly from due S to SSW-SW at the moment. Enough cooler SSTS
remain nearshore to keep winds aloft from mixing down to the
ocean sfc. This is evidenced with Johnny Mercer Pier at 10 to 15
kt wind speeds with latest SSTS at low to mid 60s...and Frying
Pan Shoals buoy at 20 to 30 kt wind speeds with latest SSTS in
the mid to upper 70s. Thus, will forecast the ILM coastal waters
basically in the middle of these 2 extremes.
Significant seas will run 4 to 7 ft for the ILM SC Waters and 4
to 8 ft for the ILM NC Waters. The higher seas will occur across
locations with the higher SSts and thus hier wind speeds. This
includes the local waters off Cape Fear and Cape Romain.
Previous.................................................
As of 300 PM Wednesday...South winds of around 20 knots are
occurring over the waters this afternoon well ahead of cold
front that is located just west of Georgia to southern
Mississippi. As the front moves closer to the coastal waters the
winds will become southwest and increase to 20 to 25 knots with
higher gust. Seas are running between 4 and 6 feet from 20
miles offshore to the coast. Seas are expected to increase to 5
to 7 feet overnight. A small craft advisory will continue for
all the water through the night.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...At sunrise the cold front will be
approaching the coastal waters and will move across the waters
during the morning. As the winds direction shifts behind the cold
front they will weaken, and the seas will diminish below small craft
conditions south of Little River around 7 AM and 10 AM north of
Little River.
By Thursday evening, the winds will shift from the west to the
northwest by Thursday evening, and remain north to northwest through
Friday night. Winds will relax to 10 knots by Friday and seas will
settle out around 2 to 3 feet during this time frame.
LONG TERM /SATURDAY THROUGH SUNDAY/...
As of 300 PM Wednesday...Canadian high pressure over the Mid-
Mississippi Valley will build east into the Carolinas early
Sunday, weakening slightly as the centers sits across the
interior of both states Sunday night. Moderate offshore breezes
Saturday should gradually die down Saturday night, but may get re-
energized Sunday night as a wave of low pressure begins to take
shape along the Georgia coast late.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 7 AM EST Thursday for AMZ254-256.
Small Craft Advisory until 10 AM EST Thursday for AMZ250-252.
&&
$$
SYNOPSIS...DCH
NEAR TERM...DCH/DRH
SHORT TERM...DRH
LONG TERM...TRA
AVIATION...RAN
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
736 PM CST Wed Nov 30 2016
.UPDATE...
736 PM CST
The going forecast for tonight and Thursday morning remains in
good shape with the message being occasional sprinkles trending
more patchy light snow showers/flurries overnight, mainly north,
and some flurries/sprinkles lingering into the morning commute.
Temperatures should be nearly steady with a wind chill in the mid
20s, and overall impact of precip looks to remain low.
Broad but closed upper circulation over northern Wisconsin/U.P. of
Michigan continues to funnel cyclonic flow across the area. One
embedded short wave is moving across southern Wisconsin, with
another more pronounced one dropping southeastward over the Twin
Cities. Light echoes over the CWA have mainly been sprinkles due
to a lack of cloud ice, but deeper saturation to colder than -10C
is improving per 00Z DVN raob and upstream infrared satellite
imagery. The DVN WFO was receiving flurries as of 715 pm as
verification of this.
The second disturbance still is timed to rotate over far northern
Illinois overnight as mentioned in previous discussion, providing
the best time for associated scattered snow showers. Lift remains
slightly below the DGZ in RAP and NAM guidance, and the lift is
not that great to begin with nor are lapse rates, so expecting the
showers to be mostly light and non-accumulating while pockets of
just flurries are more common. The short wave is forecast to be
east of the area by 6 a.m., with patchy flurries during the
commute time.
MTF
&&
.SHORT TERM...
253 PM CST
Through Thursday...
Main concern is isolated to scattered snow showers and flurries
tonight into Thursday morning.
Initial shortwave bringing isolated to scattered shower/sprinkle
activity can be seen on W/V across eastern Iowa this afternoon.
This wave will pivot northeastward, giving a glancing blow to
north central Illinois, where the highest chance range PoPs have
been focused into this evening. Farther south and east, chances
for any measurable precip will be lower, so kept PoPs in slight
chance range, though did expand them southward to account for
current radar observations. Latest guidance suggests that the
shortwave more likely to focus forcing into northeast Illinois
and northwest Indiana will swing through overnight. This is when
the highest chance PoPs have been expanded east-southeast toward
the Chicago area and northwest Indiana. Temperatures are likely
to remain primarily above freezing tonight, again with rain-snow
showers favored earlier on and then transitioning to all snow
showers with time this evening. Still not anticipating any
impacts other than perhaps brief occasional reduced visibility, as
air temps above freezing and mild road temps will prevent any
accumulations, with a dusting at most on grassy/colder surfaces.
The final trailing shortwave on the backside of the upper low will
move across the area Thursday morning, which could keep some
isolated snow showers/flurries going through mid-late AM. Any
precipitation could mix back with light rain/sprinkles before
ending. The area will remain socked in with stratus through the
day as we remain under cyclonic flow with the back edge of the
stratus way back over the Northern High Plains. Temperatures
aloft will be slightly warmer than today, but the clouds will
suppress any limited warming, so expect highs in the upper 30s to
around 40 (38-41). West winds gusting up to 20-25 mph will make
for a chilly feeling start to December and meteorological winter
despite seasonable temperatures.
Castro
&&
.LONG TERM...
241 PM CST
Thursday night through Wednesday...
A rather cloudy, and at times, active weather pattern looks to be
in place across the central CONUS through the period.
The first period of active weather could come into play on Sunday
as a northern stream mid-level disturbance tracks eastward towards
the area. There has been some questions as to the evolution of an
evolving close upper low over near the Baja of California Friday
into Saturday. Most notably, will it try to phase with the
northern stream wave. Current indications suggest that it will
not phase with the northern stream wave. As a consequence...it
appears that moisture return to the area could be modest, allowing
only light precipitation to occur over the area Sunday. P-Type
could be an issue Sunday, with the potential for snow, though with
marginal thermal profiles, we have continued the mention of rain
or snow.
Following this system it does appear there will be a day or so of
quiet weather across the area as surface high pressure builds over
the area. However, forecast confidence decreases substantially
early next week. With the southwestern CONUS/northern Mexico upper
low possibly remaining removed from the northern stream wave
moving across the region Sunday, it appears possible this system
could begin to eject northeastward sometime Monday into Tuesday as
another strong upper Trough, and an attendant speed max, digs over
the western CONUS. This could set up a period inclement weather
over the area late Monday into Tuesday. While it appears this
potential period of weather will be in the form of rain at this
time, it is possible that it could begin as a light mix Monday
night. With this possibility I have mentioned a chance for a light
rain or snow mix through early Tuesday morning.
Otherwise, there is the potential for another storm system later
next week. Forecast confidence is very high during this period,
but there have been some indications of late that a storms system
could impact the central CONUS during this period. However, the
main local impacts of this potential storm system are largely
uncertain at the present, but should be watched in the come days.
KJB
&&
.AVIATION...
For the 00Z TAFs...
Main concerns:
* MVFR cigs through the period with the potential a short period
of IFR cigs overnight.
* Snow showers/flurries this evening and overnight.
Expansive mvfr stratus deck remains in place under upper level
low pressure. Cigs have improved to higher end mvfr and low end
vfr, but anticipate that will gradually lower back to prevailing
mvfr tonight. Upstream obs are already indicating lowering cigs,
so will just go with mvfr cigs out of the gate for the 00Z update.
Upper level disturbances rotating around the southern periphery of
the upper low will bring waves of scattered snow shower activity
to the region overnight tonight and into Thursday morning.
Temperatures currently are still marginal for snow at 00Z, so pcpn
could start out as mixed rain/snow showers, but should then change
over to all snow through the evening. Have added a tempo for mvfr
vis and 1000ft cigs at ORD for a few hours after midnight, with
some of the guidance suggesting that some heavier snow shower
activity should cross nrn IL, mostly impacting RFD/DPA/ORD, but at
this point, it looks like MDW/GYY should remain south of the
potential more moderate snow showers. But, given relatively warm
ground conditions left over from temps in the 50s for the past few
days, not expecting any accumulation. Any pcpn should come to an
end by arnd 14-15z tomorrow morning and could change back over to
rain before all pcpn is done for the day.
Winds will remain west-southwest through this evening and then
gradually veer west overnight. Gusts to arnd 20kt are likely
through the night and for much of the day tomorrow.
&&
.MARINE...
312 PM CST
Westerly winds will set up over Lake Michigan this evening as
surface low pressure continues to shift northeastward over the
Upper Great Lakes. Wind speeds will be the strongest over the
southern end of the lake, where some 25 to 30 KT winds are
likely. We will continue the small craft advisory for the Indiana
shores due to waves and winds. However, we have continued to hold
off on a small craft for the Illinois shores due to the offshore
component. So, while some 25 KT winds are possibly on the
Illinois side, wave heights should remain below 4 FT. High
pressure will gradually build over the region by Saturday,
resulting in abating winds later in the week.
The weather pattern later this weekend into next week looks like
it could become active again. However, forecast confidence in
regards to the local impacts remains low this far out.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 9 PM Thursday.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
656 PM EST Wed Nov 30 2016
.SHORT TERM...(This evening through Thursday)
Issued at 417 PM EST WED NOV 30 2016
WV imagery and RAP analysis indicated a mid/upper level low over
northeast IA with troughing to the northeast through wrn Lake
Superior to James Bay. At the surface, a trough extended from wrn WI
to a developing low over se Lake Superior resulting in light winds
over most of Upper Michigan but increasing n to ne winds over west
and central Lake Superior. An area of pcpn (rain mixed with sleet)
that has lifted through n cntrl Upper Michigan into Lake Superior
and the Keweenaw was supported by 900-700 mb fgen and 285 isentropic
lift. Light lake enhanced pcpn has also slid into IWD as the low
level nrly flow edges eastward.
Tonight, expect the lake enhanced pcpn, rain changing to snow, to
expand over the wrn cwa for locations favored by nrly flow. Even
with only marginal instability (850/700 mb temps of -6C/-12C over 6C
lake surface) abundant upstream and deeper moisture along with
upslope flow will support snowfall amounts to around 2 inches. Wet-
bulb zero heights suggest that any pcpn developing over the east
half will be mainly rain.
Thursday, as the mid level low consolidates south of James Bay, the
sfc trough/low will also slide into Quebec, low level winds will
back to the southwest. Additional snowfall amounts to around 2
inches will be possible over mainly the Keweenaw and the Huron
Mountains(w of Big Bay to Herman). CAA will change the remaining
pcpn to snow over the east.
.LONG TERM...(Thursday night through Wednesday)
Issued at 255 PM EST WED NOV 30 2016
During the beginning of the medium range period, a slowly weakening
cyc nw flow arnd a slowly departing closed lo in Quebec wl cause
some lk effect pcpn into Sat. Although a passing hi pres rdg wl
bring mainly dry wx for Sat into Sun, another shrtwv/lo pres trof
aprchg fm the w wl bring a return of some pcpn later on Sun. Expect
dry wx on Mon as the trailing hi pres rdg overspreads the area.
While the fcst wl include some pops much of the time during the
medium range, pcpn and any snow totals should be on the lgt side. A
more important lo pres lifting out of the wrn trof and toward the
wrn Great Lks next Tue/Wed may result in a more sngft pcpn event
then, but model differences on the fcst are too sgnft to pin down
any details attm. Overall temps into early next week wl run aoa
normal.
Thu ngt thru Fri ngt...Although the larger scale forcing to support
pcpn wl be waning as the closed lo over wrn Quebec at 00Z on Fri
weakens and drifts slowly to the e, leaving deep lyr qvector dvgc/
subsidence over the Upr Lks, a persistent albeit weakening cyc nw
flow in the presence of plentiful llvl mstr and h85 temps within a
few degrees of -6C /compared to Lk Sup water temps in the 7-8C
range/ wl support continued lk effect pcpn. This pcpn wl be in the
form of mainly snow over the interior w half, with more of a
rain/snow mix near the warming influence of the lakes. Bumped up
pops above the consensus fcst and into the likely range in the
upslope areas favored by the expected llvl flow. The incrsgly
negative larger scale dynamics...marginally chilly h85 temps...warm
ground temps and absence of a deep dgz sug snow accums wl be a few
inches at most thru this time even over the hier terrain of the w
half.
Sat/Sat ngt...Although a sfc hi pres rdg/acyc larger scale llvl flow
extending fm Ontario into the wrn Great Lks wl drift acrs Upr MI on
Sat, many of the models depict some lgt pcpn lingering along a lk
induced lo pres trof and under some persistent llvl mstr. On Sat
ngt, the llvl flow wl shift to the s after the hi pres rdg axis
moves to the e, ending any lingering pcpn except over Lk Sup and the
ern cwa downwind of Lk MI. Any snow accums during this time wl be
under an inch.
Sun/Sun ngt...Another shrtwv/lo pres trof embedded in the more zonal
flow alf is progged to impact the area during this time. Waa/hgt
falls/uvv ahead of this disturbance wl result in some pcpn arriving
w to e on Sun. Fcst llvl thermal fields sug the pcpn wl be a rain/
snow mix, with the ptype primarily snow over the interior w half.
But since mstr inflow is progged to be marginal and the shrtwv/lo
pres trof are progged to weaken with a larger scale tendency toward
a bldg upr rdg in the Plains, expect only lgt snow accums. The sly
flow ahead of the lo pres trof off Lk MI in the presence of h85
temps still arnd -6C may result in some lk enhancement of the mixed
pcpn there. The arrival of dnva/large scale subsidence in the wake
of the passing disturbance and ahead of upr rdg/sfc hi pres in the
Plains wl cause the pcpn to diminish w-e on Sun ngt. Since h85 temps
within the trailing airmass are progged to rise toward -4C by 12Z
Mon, no lk effect pcpn is expected in the wake of the passing/
weakening trof.
Mon thru Wed...Bldg upr rdg/sfc hi pres are fcst to drift into the
wrn Great Lks on Mon, resulting in dry wx and some warmer temps as
h85 temps rebound to near 2C. Expect a return of some pops on Tue as
some waa btwn the departing sfc hi pres rdg and a shrtwv/lo pres
moving newd out of a deep wrn trof overspreads the area. The longer
range models show some sgnft differences in the evolution/track of
the sfc lo pres for next Wed that would support either rain or a
surge of colder air and some lk effect snow showers. Considering the
sgnft uncertainties, made no changes to the consensus fcst.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 655 PM EST WED NOV 30 2016
Increasing cyclonic flow on the backside of low pres organizing over
eastern Lake Superior will lead to deteriorating conditions at
KIWD/KCMX/KSAW tonight as -shsn increase in coverage. Initially,
pcpn will be a mix of snow/rain early this evening. Overall,
prevailing MVFR conditions at KIWD/KCMX will fall to IFR tonight as
-shsn coverage will be greatest over w and nw Upper MI. At KSAW, VFR
conditions initially will fall to MVFR overnight and to IFR for a
time Thu morning. Conditions at KIWD/KCMX will likely remain IFR for
much of Thu, but there may be some improvement late at KCMX as the
low shifts farther away.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 417 PM EST WED NOV 30 2016
Low pressure will linger over the western Great Lakes through
Thursday. However the pressure gradient is not expected to be as
tight with remaining below 25 knots. Northerly winds to near 30
knots are expected to develop tonight into Thursday as the slow
moving trough moves to the east of Lake Superior into Quebec. High
pressure will then build into the area into Saturday with winds
below 20 knots.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion
National Weather Service State College PA
443 AM EST Thu Dec 1 2016
.SYNOPSIS...
A large and deep storm system will move slowly through Quebec over
the next couple of days, setting up a prolonged period of cool
northwest flow over the local area. High pressure will build in
for a brief time Sunday before the next frontal system approached
early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Rain has come to an end with the front that moved east of the area
shortly after midnight. We will transition into a cooler west-
northwest flow pattern today with the usual cold season strato-cu
clouds and scattered showers of rain or snow that will mainly
favor the NW and Laurel Highlands. The low level wind field will
initially be mainly out of the west which normally confines the
best lake enhanced showers over southern NY or extreme NW Pa. I
leaned closer to HRRR POPs with the meso model confining most showers
very close to the lake during the day.
The wind is expected to become a bit more NWLY overnight which
will help bring precipitation more into my NWRN zones. However the
upstream air is only marginally cold and BUFKIT shows limited low
level instability of the air passing over the lakes so I am not
too excited about the prospects for any kind of significant lake
effect.
&&
.SHORT TERM /FRIDAY/...
The cold NW flow will remain air in place for Friday, but again
the cold air is unimpressive so NW snow shower activity is not
expected to amount to more than nuisance amounts. With high temps
expected to be above freezing, most areas will ave a hard time
making any snow stick at all.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Most areas will be precipitation free Sat-Mon except the
northwestern areas where some the over-lake trajectory will bring
the usual areas the familiar kind of lake effect showers that
happen so often in the cool season.
Sunday looks like we will see a brief respite as high pressure
moves over the state. By late Sunday into the overnight, a period
of light snow is possible as a northern stream shortwave races
through the region with a burst of warm advection. QPF looks to be
on the order of a tenth of an inch or less, but occurring
overnight many places could see their first coating of snow of the
young season.
By midweek there is decent agreement in bringing the SW US upper
low up through the OHIO Valley as a shearing out shortwave and
diffuse surface low. Unless cold air damming traps enough chilly
air in the low levels to make for some freezing rain, the precip
type with this midwest system looks to be mainly rain.
The end of the week brings some model disagreement with the
GFS/GEFS being faster than the ECMWF with the next upper trof and
frontal system. The end of the extended has just a chance of
showers given the lack of confidence.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
Surface ridging and arrival of drier air has brought improving
conditions across Central Pa early this morning, with mostly clear
skies noted over the eastern half of the state at 09Z. Further
west, residual low level moisture ascending the Appalachian Mtns
continues to result in MVFR stratocu at KBFD and KJST. Model
soundings and upstream observations support mainly MVFR CIGs at
KBFD/KJST through dawn and predominantly VFR elsewhere.
Very little change indicated during the daylight hours later
today, with persistent MVFR CIGs over the upslope region from KBFD
to KJST and possibly extending into KUNV/KAOO. A downsloping/drying
west wind should ensure VFR conds further east. After a brief lull
in the wind speeds this morning over Eastern Pa, expect a rather
gusty daytime, as stronger flow aloft begins mixing to ground
level. Bufkit soundings support frequent gusts to around 25kts
after about 14Z.
A WSW wind flow should keep lake effect snow showers mainly north
of the border today. However, latest model data suggests a slight
shift in the wind could cause the lake effect snow showers to move
from upstate NY into NW Pa tonight. Thus, IFR vis reductions
appear possible at KBFD tonight.
Outlook...
Fri-Sat...MVFR CIGS and ocnl SHSN/IFR vis possible KBFD/KJST.
Sun...Slight chance of light snow/reduced vis at night.
Mon...No sig wx expected.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...DeVoir/La Corte
SHORT TERM...La Corte
LONG TERM...La Corte
AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Duluth MN
321 AM CST Thu Dec 1 2016
.SHORT TERM...(Today through Friday)
Issued at 320 AM CST Thu Dec 1 2016
Low pressure centered near the Ontario and Quebec border will
move slowly east today into tonight. Cyclonic flow, low level
moisture, and colder air will support light precipitation today
over the Northland. A gravity wave feature was observed along the
North Shore into northern Douglas county as well and the RAP
suggests it will remain in some form today. Moisture was deep
enough into colder air aloft to support mostly light snow early
this morning with surface temperatures warm enough in a few spots
to support light rain or drizzle. We do expect the coverage of the
precipitation to diminish through the day over much of the
Northland. There will be a loss of mid level moisture today into
tonight over portions of the Northland which will cause the
precipitation to mix with or become freezing drizzle or drizzle
where it lingers.
Colder air flowing over Lake Superior will cause lake effect snow to
become more widespread through the day along portions of the South
Shore, continuing into tonight. There may be a mix that occurs
close to Lake Superior due to the warmer lake temperatures. The
low level flow will back this afternoon into this evening to more
northwest which will is less than ideal for lake effect snow over
the snowbelt of Ashland and Iron counties. Snowfall from 2 to 4
inches will be possible today into tonight, mainly over northern
Iron county. There could be some locally higher amounts as well.
Outside of the lake effect precipitation, we expect mainly dry
conditions over the rest of the Northland tonight into Friday. It
is possible there could be some patchy freezing drizzle/flurries
in spots but we don`t think it will be widespread enough to include
at this time.
We expect highs today in the upper twenties to mid thirties with
highs in the upper twenties to lower thirties on Friday.
.LONG TERM...(Friday night through Wednesday)
Issued at 320 AM CST Thu Dec 1 2016
The next weather system to affect the region is progged to traverse
the Upper Midwest late Saturday night and Sunday. A broad lower
tropospheric warm advection pattern should be the primary forcing
mechanism for ascent and precip production. There is still no true
arctic air in place this weekend, and thus, temps will be
sufficiently warm that some precip could be in the form of rain
during the day on Sunday.
Short wave ridging then builds briefly into the Upper
Midwest/Western Great Lakes region Sunday night into Monday night as
a low level Pacific-type airmass once again takes up residence over
the region. While we do not have PoPs mentioned during this time
period right now, it is entirely possible that a mention of
drizzle/freezing drizzle/flurries/fog may eventually need to be
added, as low level clouds are unlikely to clear with persistent
weak low level ascent.
Thereafter, the pattern becomes very active for the rest of next
week as the medium range models all suggest that another significant
winter storm will take shape over the middle part of the country
during the Tues-Thurs time frame. It should be emphasized at this
point that any specific forecasts of snow/ice/blizzard conditions
for any particular area directly from deterministic model data
should be taken with a very large grain of salt, as both the
GFS/ECMWF have exhibited considerable inconsistency with timing and
placement both from run to run and between models. With that said,
both medium range models seem to be slowly coming to the consensus
that this system will have a deep fetch of quality low level
moisture supplied by 48+ hours of southerly flow northward through
the Mississippi Valley in the warm sector, and an ample supply of
true arctic air flooding southward on the west side of the trof
axis. Typically this time of year, when an amplifying full latitude
trof has these two ingredients to work with, there is often
something quite significant that eventually results. Therefore,
there is at least some potential for 1) significant snow
accumulations, 2) a band of wintry mixed precipitation, and 3) some
thunderstorms, followed by 4) the first true outbreak of arctic air
across the Northland by the end of next week. Details on the
strength of any potential storm, as well as timing and placement
of precipitation will come into focus over the next few days, and
it will be an excellent idea for anyone with weather interests
across the region to stay current with the latest information over
the coming days.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1146 PM CST Wed Nov 30 2016
The low pressure system that has impacted the Northland TAF sites
over the past many periods will gradually start to lose its grip
on the Northland over the next day or so. Some snow showers will
continue off and on overnight, and into Thursday, but the trend
will be to taper off with time. Sky cover will be highly variable
with some VFR mixed in with MVFR/IFR. We should see mainly MVFR on
Thursday during the day, along with some VFR. There could be a bit
of patchy freezing drizzle late in the night, especially at KINL
and KHIB, but it is expected to be limited in duration and amount.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 31 26 30 24 / 30 10 10 0
INL 29 24 29 21 / 20 10 10 10
BRD 33 25 29 21 / 20 10 10 0
HYR 34 26 31 24 / 30 10 10 10
ASX 34 29 33 26 / 40 20 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...Melde
LONG TERM...Miller
AVIATION...DAP
Area Forecast Discussion
National Weather Service Marquette MI
500 AM EST Thu Dec 1 2016
.SHORT TERM...(This evening through Thursday)
Issued at 417 PM EST WED NOV 30 2016
WV imagery and RAP analysis indicated a mid/upper level low over
northeast IA with troughing to the northeast through wrn Lake
Superior to James Bay. At the surface, a trough extended from wrn WI
to a developing low over se Lake Superior resulting in light winds
over most of Upper Michigan but increasing n to ne winds over west
and central Lake Superior. An area of pcpn (rain mixed with sleet)
that has lifted through n cntrl Upper Michigan into Lake Superior
and the Keweenaw was supported by 900-700 mb fgen and 285 isentropic
lift. Light lake enhanced pcpn has also slid into IWD as the low
level nrly flow edges eastward.
Tonight, expect the lake enhanced pcpn, rain changing to snow, to
expand over the wrn cwa for locations favored by nrly flow. Even
with only marginal instability (850/700 mb temps of -6C/-12C over 6C
lake surface) abundant upstream and deeper moisture along with
upslope flow will support snowfall amounts to around 2 inches. Wet-
bulb zero heights suggest that any pcpn developing over the east
half will be mainly rain.
Thursday, as the mid level low consolidates south of James Bay, the
sfc trough/low will also slide into Quebec, low level winds will
back to the southwest. Additional snowfall amounts to around 2
inches will be possible over mainly the Keweenaw and the Huron
Mountains(w of Big Bay to Herman). CAA will change the remaining
pcpn to snow over the east.
.LONG TERM...(Friday through Wednesday)
Issued at 458 AM EST THU DEC 1 2016
Fri into Fri night: Models indicate the closed low over sw Quebec
will weaken and lift east toward New England late Fri. Behind the
low, cold air will linger over the Upper Great Lakes under a
cyclonic nnw flow. However 850 mb temperatures progged to be in the
-5C to -6C range will only be marginally cold enough to support lake
effect pcpn with Lake Superior sfc temps of 6-7C. Snow will be the
primary precip type although a mix of rain is possible along the
shoreline and east during the daytime hours on Fri. Given the
general absence of enhancement and a fairly elevated dgz expect any
snow accums to be inch or less.
Sat into Sat night: Light lake effect precipitation supported by low-
level convergence should be dwindling or ending over the east half
by afternoon or evening as the high pressure ridge axis moves across
Upper Michigan and winds back more west to southwest.
Sun into Sun night: Models indicate that the next shortwave trough
in zonal flow aloft will move in from the Northern Plains late Sun
into Sun night. Deep layer q-vector convergence ahead of this
shortwave will result in pcpn spreading w to e across the cwa on
Sun. Pcpn will be mostly in the form of snow over the west half but
will be more a mix of rain and snow east half due to moderation from
Lake Mi in southerly flow ahead of shortwave. 850 mb temps
-6 to -7c should be sufficiently cold enough given Lake Mi sfc temps
of 9C for some lake enhancement of pcpn into Schoolcraft and Luce
counties Sun into Sun evening which could produce some accumulating
snow well inland from Lake Mi. Given limited moisture inflow with the
system expect most system snow amounts to be generally less than an
inch.
Monday into Thursday: Models trending toward more amplified pattern
for next week as a 120+ kt 300-250 mb jet max and assoc shortwave
energy digging in from the eastern Pacific will carve out a broad
mid-upper level trough over the Western CONUS by early next week.
Model consensus of downstream ridging into the Great Lakes region in
response to the developing western CONUS trough will keep Upper Mi
mostly dry Mon into Mon night with a slight warming trend. Model
uncertainty increases from Tue into late week with the 00Z GFS being
much more progressive than 00Z ECMWF and Canadian with stronger
shortwave energy ejecting out of base of western CONUS trough. Given
uncertainty will use model consensus for pops which tend to keep
area dry from Mon into most of Tue but then brings in pcpn for Tue
night into Wed. Evolution/track of developing strong sfc low is very
much in question so initial pcpn for Tue night into Wed may end up
being more of a mix of rain/snow and then transition to more lake
enhanced/lake effect snow for late next week. Once cold advection
ensues behind the system, there will also likely be a period of
stronger winds accompanying lake effect snow later in the week. &&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1154 PM EST WED NOV 30 2016
Cyclonic flow on the backside of low pres over eastern Lake Superior
will result in mostly prevailing IFR conditions with -shsn at
KIWD/KCMX/KSAW overnight into the morning hrs. With a more direct
upslope flow, IFR conditions will be most persistent at KIWD with
even some LIFR at times overnight. -Shsn will continue today,
especially at KIWD/KCMX. Conditions should also improve to low MVFR,
though IFR may tend to hang on at KIWD.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 417 PM EST WED NOV 30 2016
Low pressure will linger over the western Great Lakes through
Thursday. However the pressure gradient is not expected to be as
tight with remaining below 25 knots. Northerly winds to near 30
knots are expected to develop tonight into Thursday as the slow
moving trough moves to the east of Lake Superior into Quebec. High
pressure will then build into the area into Saturday with winds
below 20 knots.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Voss
AVIATION...Rolfson
MARINE...JLB
Area Forecast Discussion
National Weather Service State College PA
704 AM EST Thu Dec 1 2016
.SYNOPSIS...
A large and deep storm system will move slowly through Quebec over
the next couple of days, setting up a prolonged period of cool
northwest flow over the local area. High pressure will build in
for a brief time Sunday before the next frontal system approached
early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Rain has come to an end with the front that moved east of the area
shortly after midnight. We will transition into a cooler west-
northwest flow pattern today with the usual cold season strato-cu
clouds and scattered showers of rain or snow that will mainly
favor the NW and Laurel Highlands. The low level wind field will
initially be mainly out of the west which normally confines the
best lake enhanced showers over southern NY or extreme NW Pa. I
leaned closer to HRRR POPs with the meso model confining most showers
very close to the lake during the day.
The wind is expected to become a bit more NWLY overnight which
will help bring precipitation more into my NWRN zones. However the
upstream air is only marginally cold and BUFKIT shows limited low
level instability of the air passing over the lakes so I am not
too excited about the prospects for any kind of significant lake
effect.
&&
.SHORT TERM /FRIDAY/...
The cold NW flow will remain air in place for Friday, but again
the cold air is unimpressive so NW snow shower activity is not
expected to amount to more than nuisance amounts. With high temps
expected to be above freezing, most areas will ave a hard time
making any snow stick at all.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Most areas will be precipitation free Sat-Mon except the
northwestern areas where some the over-lake trajectory will bring
the usual areas the familiar kind of lake effect showers that
happen so often in the cool season.
Sunday looks like we will see a brief respite as high pressure
moves over the state. By late Sunday into the overnight, a period
of light snow is possible as a northern stream shortwave races
through the region with a burst of warm advection. QPF looks to be
on the order of a tenth of an inch or less, but occurring
overnight many places could see their first coating of snow of the
young season.
By midweek there is decent agreement in bringing the SW US upper
low up through the OHIO Valley as a shearing out shortwave and
diffuse surface low. Unless cold air damming traps enough chilly
air in the low levels to make for some freezing rain, the precip
type with this midwest system looks to be mainly rain.
The end of the week brings some model disagreement with the
GFS/GEFS being faster than the ECMWF with the next upper trof and
frontal system. The end of the extended has just a chance of
showers given the lack of confidence.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Surface ridging and arrival of drier air has brought improving
conditions across Central Pa early this morning, with mostly clear
skies noted over the eastern half of the state at 12Z. Further
west, residual low level moisture ascending the Appalachian Mtns
is resulting in MVFR stratocu across the western and central part
of the state.
Very little change indicated later today, with persistent MVFR
CIGs over the upslope region from KBFD to KJST and possibly
extending into KUNV/KAOO. A downsloping/drying west wind should
ensure VFR conds further east. After a brief lull in the wind
speeds this morning over Eastern Pa, expect a rather gusty
daytime, as stronger flow aloft begins mixing to ground level.
Bufkit soundings support frequent gusts to around 25kts across the
entire region later today.
A WSW wind flow should keep lake effect snow showers mainly north
of the border today. However, latest model data suggests a slight
shift in the wind could cause the lake effect snow showers to move
from upstate NY into NW Pa tonight. Thus, IFR vis reductions
appear possible at KBFD tonight.
Outlook...
Fri-Sat...MVFR CIGS and ocnl SHSN/IFR vis possible KBFD/KJST.
Sun...Slight chance of light snow/reduced vis at night.
Mon...No sig wx expected.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...DeVoir/La Corte
SHORT TERM...La Corte
LONG TERM...La Corte
AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Duluth MN
911 AM CST Thu Dec 1 2016
.UPDATE...
Issued at 911 AM CST Thu Dec 1 2016
Updated to add chance of freezing drizzle across areas north of
iron range and arrowhead for this morning. Have receive ed
reports of ZL- in those areas. The threat for s-/ZL- still looks
possible for the rest of the day with the low clouds and abundant
low level moisture across the area. Rest of fcst unchanged.
UPDATE Issued at 558 AM CST Thu Dec 1 2016
An updated aviation discussion is below for the 12Z TAF issuance.
UPDATE Issued at 449 AM CST Thu Dec 1 2016
Impressive gravity wave induced precipitation band has formed
this morning along the North Shore into Douglas and Pine counties
this morning. The low level flow was north from 15 to 20 knots
through 850mb per KDLH VWP. NAM BUFR soundings show a strong low
level inversion. Both the NAM and RAP show the gravity wave
continuing through much of the day. However, they also show low to
mid level moisture diminishing this morning into the afternoon
which would cause the precipitation to diminish. The intensity of
the band of precipitation has already shown some signs of
weakening but the conditions responsible for it remain. We
increased POPs quite a bit for this morning and have some snow
accumulation up to 2 inches. There is uncertainty if this band of
precipitation will maintain its strength and if so for how long.
Surface temperatures were from 32 to 36 degrees as of 11Z and a
mix of rain and snow will be more likely close to the lake with
mostly snow inland.
&&
.SHORT TERM...(Today through Friday)
Issued at 320 AM CST Thu Dec 1 2016
Low pressure centered near the Ontario and Quebec border will
move slowly east today into tonight. Cyclonic flow, low level
moisture, and colder air will support light precipitation today
over the Northland. A gravity wave feature was observed along the
North Shore into northern Douglas county as well and the RAP
suggests it will remain in some form today. Moisture was deep
enough into colder air aloft to support mostly light snow early
this morning with surface temperatures warm enough in a few spots
to support light rain or drizzle. We do expect the coverage of the
precipitation to diminish through the day over much of the
Northland. There will be a loss of mid level moisture today into
tonight over portions of the Northland which will cause the
precipitation to mix with or become freezing drizzle or drizzle
where it lingers.
Colder air flowing over Lake Superior will cause lake effect snow to
become more widespread through the day along portions of the South
Shore, continuing into tonight. There may be a mix that occurs
close to Lake Superior due to the warmer lake temperatures. The
low level flow will back this afternoon into this evening to more
northwest which will is less than ideal for lake effect snow over
the snowbelt of Ashland and Iron counties. Snowfall from 2 to 4
inches will be possible today into tonight, mainly over northern
Iron county. There could be some locally higher amounts as well.
Outside of the lake effect precipitation, we expect mainly dry
conditions over the rest of the Northland tonight into Friday. It
is possible there could be some patchy freezing drizzle/flurries
in spots but we don`t think it will be widespread enough to include
at this time.
We expect highs today in the upper twenties to mid thirties with
highs in the upper twenties to lower thirties on Friday.
.LONG TERM...(Friday night through Wednesday)
Issued at 320 AM CST Thu Dec 1 2016
The next weather system to affect the region is progged to traverse
the Upper Midwest late Saturday night and Sunday. A broad lower
tropospheric warm advection pattern should be the primary forcing
mechanism for ascent and precip production. There is still no true
arctic air in place this weekend, and thus, temps will be
sufficiently warm that some precip could be in the form of rain
during the day on Sunday.
Short wave ridging then builds briefly into the Upper
Midwest/Western Great Lakes region Sunday night into Monday night as
a low level Pacific-type airmass once again takes up residence over
the region. While we do not have PoPs mentioned during this time
period right now, it is entirely possible that a mention of
drizzle/freezing drizzle/flurries/fog may eventually need to be
added, as low level clouds are unlikely to clear with persistent
weak low level ascent.
Thereafter, the pattern becomes very active for the rest of next
week as the medium range models all suggest that another significant
winter storm will take shape over the middle part of the country
during the Tues-Thurs time frame. It should be emphasized at this
point that any specific forecasts of snow/ice/blizzard conditions
for any particular area directly from deterministic model data
should be taken with a very large grain of salt, as both the
GFS/ECMWF have exhibited considerable inconsistency with timing and
placement both from run to run and between models. With that said,
both medium range models seem to be slowly coming to the consensus
that this system will have a deep fetch of quality low level
moisture supplied by 48+ hours of southerly flow northward through
the Mississippi Valley in the warm sector, and an ample supply of
true arctic air flooding southward on the west side of the trof
axis. Typically this time of year, when an amplifying full latitude
trof has these two ingredients to work with, there is often
something quite significant that eventually results. Therefore,
there is at least some potential for 1) significant snow
accumulations, 2) a band of wintry mixed precipitation, and 3) some
thunderstorms, followed by 4) the first true outbreak of arctic air
across the Northland by the end of next week. Details on the
strength of any potential storm, as well as timing and placement
of precipitation will come into focus over the next few days, and
it will be an excellent idea for anyone with weather interests
across the region to stay current with the latest information over
the coming days.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 558 AM CST Thu Dec 1 2016
Large upper low will continue to slowly weaken and move away from
the region today/tonight, with north/northwest winds persisting
through the period. There is sufficient wrap-around moisture for
MVFR and perhaps some short periods of IFR ceilings to persist,
along with some periods of light snow or flurries. However, precip
and fog should not limit visibility too much today or tonight.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 34 26 30 24 / 30 10 10 0
INL 33 24 29 21 / 20 10 10 10
BRD 34 25 29 21 / 30 10 10 0
HYR 34 26 31 24 / 30 10 10 10
ASX 34 29 33 26 / 40 20 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...Stewart