Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/22/16
Area Forecast Discussion
National Weather Service Bismarck ND
933 PM CST Mon Nov 21 2016
.UPDATE...
Issued at 933 PM CST Mon Nov 21 2016
No significant changes were made with this update. Precipitation
is finally starting to reach the ground in the James River valley
per recent Jamestown ASOS observations. The 00 UTC Bismarck and
Aberdeen RAOBs revealed a substantial dry layer below 600 mb and
thus it`s not surprising that it has taken several hours for any
hydrometeors to reach the ground. Having said that, recent radar
trends have shown a distinct uptick in reflectivity at the lowest
altitude, further suggesting precipitation will begin in earnest
in the James River valley in the next few hours. The 00 UTC RAOBs
also showed a substantial warm layer aloft that exceeded most of
the model expectations, further supporting freezing rain. The 00
UTC NAM and recent RAP/HRRR simulations are also still very much
in line with the freezing rain advisory.
We should note that based on radar trends, we are a bit concerned
that an expansion of the freezing rain advisory into McIntosh and
Logan Counties may be necessary. However, road temperatures in
those areas are above freezing as of 03 UTC so it`s not clear if
impacts will be long-lived enough to warrant an advisory. We will
continue to monitor trends the next few hours.
UPDATE Issued at 551 PM CST Mon Nov 21 2016
We added a slight chance of rain to the early-evening forecast a
bit further west into west central and central ND with this update
in response to an area of more prominent radar returns centered on
Dunn County as of 2345 UTC. Otherwise, the going forecast remains
on track and was only blended to current observations. Trends in
late afternoon surface observations and radar imagery show clouds
above 10,000 ft AGL despite increasing reflectivity, suggesting
the lower atmosphere will take time to saturate this evening
before precipitation reaches the ground. That being said, recent
HRRR simulations and the 18 UTC GFS and NAM still support the
previously-issued freezing rain advisory for the James River
valley. Evaluation of flow on isentropic surfaces centered around
300 K favors vertical motion and thus the greatest precipitation
coverage peaking a few hours either side of 06 UTC.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 347 PM CST Mon Nov 21 2016
Forecast highlights in the short term period will be freezing
rain/sleet over central ND, with ice accumulations expected in the
James River Valley and surrounding areas.
Currently, southwest flow aloft with an embedded wave lifting
through the Dakotas and a slow moving west to east surface trough
moving into the western Dakotas. Large area of light radar returns
over much of the region, through cloud bases above 10K FT AGL
producing mostly virga at this time.
Low level forcing associated with the approaching sfc trough will
combine with increasing divergent flow aloft tonight. Coupled
with a surge of boundary layer moisture moving northward into
south central and eastern ND tonight, cloud bases will lower and
we will start seeing precipitation over my south central and
eastern counties mainly after 00Z, although may also start seeing
light rain/drizzle some areas this afternoon. Warm temperatures
aloft so once air or surface temperatures cool after dark to
freezing, will see a good chance for light freezing rain or sleet
mixing with light rain. Most favorable area for ice accumulations
will be across the James River Valley, and have issued a Freezing
Rain Advisory for this area from this evening through mid morning
Tuesday when the precipitation type should be changed over the
snow due to evaporational cooling and/or CAA.
.LONG TERM...(Tuesday night through Monday)
Issued at 347 PM CST Mon Nov 21 2016
Jet stream aloft remains over the northern to central tier of the
United States through the extended period, but then shows signs of
dipping farther south afterwards as we approach December.
Fairly active flow pattern with the upper level jet near or aloft
for the remainder of this week and into the following weekend.
Will see a couple of larger scale S/WV`s moving east along the
flow bringing moisture and temperature swings to the region. The
first wave is forecast to move through Thanksgiving day and will
bring some light snow to the region, nothing impactful as of now.
Next feature then moves through this coming weekend, again nothing
impactful expected at this time. Warmest day will be Saturday
with possible widespread 40s/possible low 50s, otherwise seasonal
or below highs and lows expected (Highs in the 20s/30s, Lows in
the single digits/teens).
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 933 PM CST Mon Nov 21 2016
Light freezing rain will occur in the James River valley tonight.
Precipitation will likely change to a mix of light sleet or snow
before ending early Tuesday. KJMS will be impacted. Confidence in
precipitation is lower elsewhere, but there is also a chance of
light freezing rain in central ND tonight. We also expect ceilings
to lower tonight with MVFR and local IFR cloud decks in central ND
after 06 UTC. Patchy fog is also possible. Finally, a separate
area of MVFR to IFR ceilings is forecast to move into northwest
and north central ND Tuesday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Freezing Rain Advisory until 9 AM CST Tuesday for NDZ025-037-048-
051.
&&
$$
UPDATE...CJS
SHORT TERM...NH
LONG TERM...NH
AVIATION...CJS
Area Forecast Discussion
National Weather Service State College PA
1058 PM EST Mon Nov 21 2016
.SYNOPSIS...
Windy conditions will persist through tonight as a large upper
low over New England slowly lifts northeast toward the Canadian
maritimes. Weakening low pressure lifting out of the Mississippi
Valley will likely track just north of Pennsylvania by midweek,
bringing moderating temperatures and a chance of rain showers
Wednesday night and Thursday. Mixed precipitation will be possible
across northern portions. Another cold front will cross the
commonwealth Friday night and Saturday, delivering another brief
punch cold air.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
730 PM update...
Thought about extending the wind advy for the NErn counties, as
mixed layer still rather deep and wind gusting around 40kts at ELZ
in the last hour. However, the inversion should continue to lower.
But, for the next 6 -12 hours, gusts could be 30-40kts at times.
Have maintained sct POPs a little longer into the night, and
mentioned flurries slightly downstream of the slight chc POPs all
night.
Prev...
Inversion heights remain around 7k feet maintaining lake effect
snow flurries across the Laurel Highlands...West Central and
Northwest Mountains. Accums if any are light...and the bigger
story remains the wind across central and eastern PA
especially...where gusts have eclipsed 40 mph in some spots.
Slowly diminishing wind will occur tonight as brisk and deeply
channeled northwest flow persists overhead. Won`t see significant
improvement in the wind until later on in the daytime Tuesday in
fact.
Inversion heights are just shy of 7k feet this afternoon...and
lower sufficiently after midnight for flurries and snow showers to
diminish. Carrying additional accums less than one inch from the
West Central and Northwest Mountains. Latest HRRR in agreement
with this thinking...and continues to even hint at a weak Lake
Huron band persisting into the pre dawn hours Tuesday morning.
Well mixed boundary layer tonight with fairly uniform mins ranging
from the mid 20s northwest to around 30F southeast.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
Surface ridge builds into the state on Tuesday...allowing
inversion heights to continue to fall. Any lingering flurries and
snow showers will end by afternoon as 1028 mb ridge builds through
Ohio. This will bring brightening skies and a more pleasant
afternoon...although it will remain breezy. Highs will range from
the mid 30s north to the mid 40s southeast.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
High pressure will build in for Tuesday night and early Wednesday
before we begin to be affected by the warm air advection ahead of
the next approaching frontal system.
Precipitation type issues could arise as the precipitation
associated with the frontal system begins to move into the region
with air and wet bulb temperatures aloft that will be marginally
cold over about the northern half or so of the forecast area. I
inserted the mention of pockets of freezing rain or sleet
Wednesday night into early Thursday morning with surface
temperatures dropping to freezing in some of the northern normal
cold spots. It doesn`t look like a big QPF event but things could
potentially get slippery for a time when holiday travel will be
ramping up.
The 12Z GFS/ECMWF both weaken the cold/occluded front as it
enters the state Thanksgiving Day in favor of a new low that they
form along or just off the eastern seaboard. This low gradually
deepens into a single strong ocean storm over the coastal waters
east of New England Friday night and Saturday. With at least a
pair of upper shortwaves responsible for these developments
slated to push through, it looks good for us to stay unsettled
right through Saturday before a ridge can replace the cyclonic NW
flow aloft and bring drying conditions for the second half of the
weekend.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
While the strong winds persist the moisture flow has shifted
northward with only light snow showers at BFD. This is currently
the only site with MVFR cigs and vsbys. Expect for conditions to
be VFR overnight elsewhere. The SFC will slowly decouple as the
temperatures drop. However, the winds aloft will persist through
tomorrow afternoon. Strong winds/gusts with sustained winds of
18-25 mph will continue until around 18Z to 21Z before very
gradually relaxing as high pressure builds eastward across the
region.
Outlook...
Wed...No significant weather expected.
Wed night and Thursday...MVFR to IFR conditions as periods of rain
spread east across the state. Mixed precipitation/icing possible
across the northern and western mountains of PA.
Fri...Restrictions likely N/W with scattered rain showers.
Sat...Restrictions possible N/W with scattered snow showers.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...DeVoir
NEAR TERM...Dangelo/DeVoir
SHORT TERM...DeVoir
LONG TERM...La Corte
AVIATION...Ceru/RXR
Area Forecast Discussion
National Weather Service Grand Forks ND
1002 PM CST Mon Nov 21 2016
.UPDATE...
Issued at 1002 PM CST Mon Nov 21 2016
Upper level trough was over southern SASK with an upper level jet on
the southeast side of the trough. Precipitation tonight and Wed will
remain under the 700 hpa theta-e ridge.
Observed sounding indicate a fairly strong inversion over the area
Observed sounding at ABR shows the lower layers are drier than
GFS model forecast. Observed warm layer is 2-3C warmer than the
RAP. Will use the RAP for warm layer aloft. Radar indicated stronger
returns over the JMS area. expected that area to expand overnight.
UPDATE Issued at 659 PM CST Mon Nov 21 2016
Upper level trough over MT will move over the forecast area by Wed.
Radar was showing precipitation over much of eastern ND. However no
precipitation was reaching the ground. Expect precip to begin
reaching the ground later this evening.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 310 PM CST Mon Nov 21 2016
Challenging forecast tonight wrt p-type and fzra potential. Will
be issuing winter weather advisory for all areas except the far
eastern counties with a mixed winter weather precipitation
event expected. An elongated inverted trough with mid level WAA
will slowly shift over the forecast area this evening. Area radars
already showing some echos across the Dakotas and into southern
Canada. 12Z area RAOBs this morning indicated a strong dry layer
creating just virga so far with the radar returns. As a result
there will be freezing drizzle chances until the that lower layer
saturates. Freezing rain is expected to be the main impact for
much of the overnight as models continue to showing 850mb temps
and wet bulb temps rising to plus 6C then only cooling to 2C to 4C
once pcpn starts. Temps aloft very slowly cool from west to east
with freezing rain turning to snow Tuesday. Ice accumulations
will be up to a tenth of an inch with the higher amounts in the
eastern ND and snow totals ranging from 1 to 3 inches in SE ND and
the central valley with a 2 to 4 inch range in the northern
valley and NW MN. There does seem to be the potential for a little
stronger band of snow setting up somewhere in the northern valley
or NW where accumulations may be greater than 4 inches.
.LONG TERM...(Tuesday night through Monday)
Issued at 310 PM CST Mon Nov 21 2016
The early periods will be impacted by the next wintry weather event
(short term) that will wind down in the far east on Wednesday as
snow tapers off and the system pulls off into the upper Great Lakes.
Snowfall accumulations of two to four inches are most likely across
the northern and eastern portions of the CWA by mid afternoon Wed.
An upper ridge then moves over the plains by late Wed night but with
fairly zonal flow, another much weaker wave will move over the
central plains and bring a chance for some scattered snow showers
across the southern valley on Thursday afternoon. A more amplified
upper ridge then moves over the area on Thursday night into Friday
and should provide a bit of a break in the wintry weather bursts
through at least Saturday, with a chance of some light snow in the
far northeast (Baudette area) on Sunday afternoon. Daytime highs in
the long term will generally be in the mid to upper 30s...with
slightly warmer temperatures in the west on Friday afternoon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 659 PM CST Mon Nov 21 2016
VFR conditions were across the area with cigs 10 thousand ft or
higher. Expect cigs to lower tonight first on the ND side of the Red
River as precip continues to fall in the dry lower layers. Expect
MVFR/IFR conditions by 12Z Tue on the ND side. Expect IFR
conditions to spread east through the day Tue.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Weather Advisory until 6 AM CST Wednesday for NDZ008-016-
027.
Winter Weather Advisory until 6 AM CST Wednesday for NDZ006-007-
014-015-024-026-028>030-038-039-049-052>054.
MN...Winter Weather Advisory until 6 AM CST Wednesday for MNZ001-002-
004-005-007-008-013>015-022-027.
Winter Weather Advisory until 6 AM CST Wednesday for MNZ003-029-
030-040.
&&
$$
UPDATE...Hoppes
SHORT TERM...JK
LONG TERM...Speicher
AVIATION...Hoppes
Area Forecast Discussion
National Weather Service Green Bay WI
542 PM CST Mon Nov 21 2016
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 212 PM CST Mon Nov 21 2016
Quiet conditions to continue across northeast WI for about another
24-30 hours as a ridge of high pressure slowly moves across the
Great Lakes. Main forecast issue to again be on temperatures
tonight as evening clear skies become mostly cloudy by daybreak
as high clouds overspread the region. A secondary concern has to
do with the timing of the leading edge of precipitation late on
Tuesday, but it now appears that most of the precipitation will
hold off until after sunset across central WI.
The 20z MSAS surface analysis showed the ridge of high pressure
extended from western Ontario south through the Great Lakes to the
TN Valley. Visible satellite imagery had picked up on the high
clouds overspreading the northern Plains/Midwest with mid-clouds
over the central Plains. Current temperatures were near normal
values for late-November.
The surface ridge axis will continue to slowly drift east tonight
due to blocking system located over the Canadian maritimes.
Meanwhile, the system of interest is forecast to move across the
central/southern Rockies with southerly winds in advance of the
developing surface low to begin tapping gulf moisture. For
northeast WI, look for high clouds to start overspreading the area
during the overnight hours, but with winds being light/variable,
temperatures could still tank across northern WI where there is
snow on the ground. Latest thinking would be to have mins range
from 10 to 15 above north, upper teens to lower 20s east-central
WI.
As the surface ridge slides farther east and the system pulls into
the central Plains on Tuesday, main question for the day will be
where the leading edge of precipitation be located? The air mass
over eastern WI appears to be rather dry at the onset, so much of
the advancing precipitation could simply go into saturation. The
NAM remains the slowest of the models with the leading edge of
precipitation just reaching western WI by 00z Wednesday. The GFS
has slowed a bit with the leading edge reaching central WI by late
in the day. Other models end up somewhere in between. Bottom line
here is that eastern WI will remain dry through Tuesday with only
a small chance pop for central WI later Tuesday afternoon. Any
precipitation that reaches north-central WI would fall as all snow
with temperatures in the lower 30s. However, central WI could be
in for a rain/snow mix (probably more rain than snow) with
temperatures in the middle to upper 30s. Eastern WI will be the
warmest with max temperatures in the upper 30s to around 40
degrees.
.LONG TERM...Tuesday Night Through Monday
Issued at 212 PM CST Mon Nov 21 2016
A rather active period this week as well as through next weekend
with a series of troughs passing over the Upper Midwest and
Western Great Lakes region nearly every other day. Lack of
widespread cold air in the region providing a mix potential for
the systems impacting the area.
First storm to deal with is the Tuesday night into Wednesday
night system. Nearly elongated surface to 850 mb lows are progged
to slide over the region. Many issues linger with this storm
system, with the arrival the first problem. A nearly stalled
stacked low centered over Maine and an upper ridge just to the
west likely will delay the arrival of the pcpn into Tuesday
evening. The GFS continues to be the quickest with the arrival
Tuesday afternoon, otherwise a blend of the remainder of the runs
suggests tuesday evening arrival time. Another issue with the
system is the snow ratios. H7 temps warmer than -10 c suggest a
limited snow growth region and forecast soundings indicating a
rain and snow mix for most locations, and mainly snow north
central. Did consider a watch for NC Wisconsin for Tuesday night
into Wednesday evening due to impact with holiday travel, but the
snow ratios with the anticipated pcpn suggests more of a long
duration advisory. Due note that some northern stream energy
drops into the northern Great Lakes later Wednesday into Wednesday
night which could further slow down the system and prolong the
accumulating snow.
With a light pressure gradient and a more compact type of snow
factoring into lesser amounts, will hold off any headlines for
now and let later shifts post advisories as needed. At this time
anticipate mainly 3 to 7 inches of snow over a 36 hour period
north of a Wausau to Wausaukee line, 1 to 3 inches just south of
this line and around and inch mixed with rain toward East Central
Wisconsin.
A quieter day is expected Thanksgiving day as a ridge of high
pressure quickly passes over the region.
A weaker system will bring a chance of mainly snow to the area
late Thursday night into Friday. The latest GFS trended further
north with a band of 1 to 2 inches of snow.
For what its worth, medium range progs then go into a series of
deeper low pressure systems starting late Sunday into next week.
ECMWF and GFS lift a deeper low into the region Sunday into
monday with timing an issue. Height 850 temps a little warmer
rising to +5 C by Sunday night over East Central Wisconsin but
cooler to the west for a mix again.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 539 PM CST Mon Nov 21 2016
High and then middle clouds ahead of the next system will
gradually overspread the area during the next 12-18 hours.
More uncertainty exists over the possibility of lake clouds
spreading back into eastern Wisconsin as the low-level flow swings
around to the east once the low-level ridge slides east of the
area. The RAP 925 RH progs are pretty supportive of this
happening--possibly late tonight but more likely tomorrow morning.
Added MVFR cloud deck to the east-central TAF sites to account for
this development.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....Kallas
LONG TERM......TDH
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Marquette MI
615 PM EST Mon Nov 21 2016
.SHORT TERM...(This evening through Tuesday)
Issued at 337 PM EST MON NOV 21 2016
Water vapor imagery and RAP analysis show a deep closed low centered
just n of New England. To the w, a ridge extends n thru the Plains
with associated sfc high pres ridge extending from western Hudson
Bay s across western Lake Superior and WI. Dry air, low inversion
and lack of much overwater fetch has resulted in the skies becoming
sunny across western Upper MI today. Continued northerly flow across
eastern Lake Superior ahead of the sfc high pres ridge axis is
maintaining stratocu into the e half of the fcst area.
Axis of sfc high pres ridge will very slowly drift e tonight, only
reaching a line from roughly Copper Harbor to Iron Mtn by 12z Tue.
This will maintain a northerly flow into the eastern fcst area thru
the night, suggesting sct-bkn even ovc stratocu may hold on thru the
night. Moderating 850mb temps from around -10C now to around -5C by
morning will cut down on the cloud cover, but band of
moisture/stratocu per vis satellite imagery n and ne of Lake
Superior will probably work to maintain greater coverage as this
moisture advects s/ssw. Clouds will help keep temps up over the e,
probably mid/upper teens well inland to mid 20s along Lake Superior.
To the w, with calm wind under sfc high pres ridge, clear skies thru
the evening and precipitable water aob 0.25 inches, favored the low
side of avbl guidance. High clouds will probably begin to increase
overnight, preventing ideal radiational cooling all night. While
traditional cold spots will fall just under 10F, certainly not of
the question for a few locations with a decent snow cover to plummet
toward 5F, perhaps lower. Coldest spots in ne MN last night were
around 5F.
Shortwave trof moving across the western CONUS currently will shift
out over the western Plains on Tue while mid level ridge shifts to
Upper MI. Although isentropic ascent begins to increase into far
western Upper MI late in the day ahead of the trof, fcst soundings
show a significant amount of low-level dry air that will need to be
overcome. Given the overall weak forcing, it`s unlikely that any
-sn will reach the KIWD area before 00z Wed. Otherwise, expect an
increase in high and mid clouds w and central thru the day. E may
end up mostly sunny for much of the day. High temps should be mostly
in the low/mid 30s.
.LONG TERM...(Tuesday night through Monday)
Issued at 357 PM EST MON NOV 21 2016
Main weather concern during this forecast period will be the
potential for snow, possibly advisory level, moving into the area
late Tuesday night through Wednesday night. This will likely cause
slippery Thanksgiving travel across the area south and westward into
WI and MN.
Tuesday night through Wednesday night: A surface low is progged to
be centered over northwest Missouri Tuesday evening before shifting
northeastward into Lower Michigan Wednesday night. Aloft, a trough
of low pressure will slide from the Plains eastward into the Great
Lakes region as it tries to becomes negatively tilted through the
same time period. Initially, fairly dry are will be in place across
the area, as a brief ridge slides through, which should keep most of
the precipitation out of the U.P. until the overnight hours Tuesday
night for the western U.P. Much of the central and east may end up
staying dry Tuesday night. Deeper moisture will be advected into the
area ahead of the low. This will sufficiently moisten the atmosphere
across the area to allow most of the U.P. to see precipitation. The
best/deeper forcing with this system will slide across the area
Wednesday afternoon into Wednesday evening as shown by overlaying
1000-500 RH and deep layer Q-Conv; however, a shortwave is progged
to slide through the area late Tuesday night into Wednesday morning,
which may help to enhance snow during that period as well. Overall
precip type will be mainly snow across the entire U.P.; however, the
far south-central locations and areas close to the Great Lakes may
see a bit of rain mix in during the day Wednesday. Otherwise, wet
bulb temps are progged to remain near or just below freezing through
the profile, except over far south central areas where the surface
temps and low level warm air may mix the snow with rain. The DGZ is
in a fairly shallow layer above the best forcing. This, coupled with
near freezing surface temps, will keep the snow ratios in check.
Overall, not really expecting to see overly impressive snowfall
totals; however, the slower movement of the system will allow the
system to produce advisory level snow, mainly over the western half
of the U.P. Generally expecting between 0.2 and 0.4 tenths of an
inch of liquid, which would equate to about 2 to 5 inches of snow
over the west half and around 1 to 2 inches over the east half with
a roughly 10:1 snow to liquid ratio. At this point, will stick with
a SPS to highlight the potential for the high moisture content snow,
which will make Thanksgiving travel plans slippery at times.
Thursday through Friday: Another surface low and 500mb wave will is
progged to slide through the Upper Great Lakes Thursday night into
Friday, which will keep a chance of rain and snow in the forecast,
although the precipitation should be much lighter. Moisture looks to
be fairly shallow overall through much of Thursday night which may
end up giving drizzle or flurries through that time period, with a
transition to more of an actual rain/snow mixture Friday.
Temperatures will be a bit warmer during this time period with highs
in the mid 30s and overnight lows in the mid 20s to around 30.
Saturday through the extended: High pressure and dry air are progged
to slide across the area Saturday and Saturday night, which allow
for a break in the precipitation. Beyond that time period, models
begin to diverge significantly, with the GFS keeping dry air and a
ridge in place while the EC slides a closed low and upper trough
through the Great Lakes. At this point, will stick with a consensus
blend of the models.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 615 PM EST MON NOV 21 2016
High pres over western Lake Superior/far western Upper MI will
slowly shift e, only reaching central Upper MI by early Tue aftn.
With the ridge drifting e of KIWD and a dry air mass now in place,
VFR conditions will prevail at KIWD thru this fcst period. KCMX will
also be VFR thru the fcst period, but as the ridge shifts e of the
terminal, developing ese wind off Lake Superior could lead to a
brief period of bkn MVFR cigs mid to late Tue morning. At KSAW, bkn
MVFR cigs could occur at times overnight as light upslope n to ne
winds continue until the high pres ridge arrives late Tue morning.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 337 PM EST MON NOV 21 2016
As a high pres ridge extending s across western Lake Superior drifts
e, reaching eastern Lake Superior Tue aftn, lingering 20-25kt winds
over eastern Lake Superior will diminish, falling blo 20kt overnight
and blo 15kt for Tue. Over the w half of the lake, winds will remain
mostly under 15kt tonight/Tue, but will increase slightly Tue aftn.
As the ridge shifts e and a low pres system emerging over the Plains
early Tue tracks ene into the western Great Lakes by Wed evening,
ese winds will increase up to 20-25kt across much of the lake Tue
night into Wed with the strongest winds occurring over central and
eastern Lake Superior. Winds will then diminish to under 15kt for
Thu-Fri as the pres gradient across the area becomes weak. Winds
will begin to increase again later Sat as a high pres ridge over the
western Great Lakes early Sat shifts e during the day.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...KEC
AVIATION...07
MARINE...Rolfson
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
834 PM CST Mon Nov 21 2016
.UPDATE...
Lowered overnight low temperatures slightly tonight. Adjusted
rain chances upwards a bit across areas northwest of I-44 after
midnight tonight. Sky cover was adjusted as well tonight, mainly
to increase it.
&&
.DISCUSSION...
Isolated to scattered showers and perhaps a few thunderstorms
are expected to affect parts of northwestern Oklahoma after
2 am tonight.
Latest radar indicated light echoes across western Oklahoma and
far western north Texas. Most, if not all, of these echoes were
not reaching the ground due to dry low levels. Regardless, kept
chance of sprinkle mention to account for this activity.
Latest HRRR runs have been consistent with allowing scattered
showers and a few thunderstorms form and move into areas northwest
of I-44 after 2 am tonight. This seems reasonable, especially
since there area current showers and storms in New Mexico as of
830 pm CST, forming ahead of an ejecting negative tilt mid-level
disturbance. This activity would quickly move northeast and bring
brief light rainfall to parts of the area. With MUCAPE up to 200
J/kg, cannot rule out a few lightning strikes as well with this
activity, though no strong storms are expected. Thus, increased
rain chances slightly northwest of I-44. Southeast of I-44, dry
weather can be expected tonight, though low stratus clouds will
likely form towards sunrise.
Lows tonight may fall a bit lower than previously forecast
especially as high level cloud cover decreases west to east
after midnight.
Products will be out shortly.
MBS
&&
.PREV DISCUSSION... /issued 541 PM CST Mon Nov 21 2016/
DISCUSSION...
The 00Z aviation discussion follows....
AVIATION...
A few -SHRA will be possible overnight and early Tuesday across
much of the western half of Oklahoma. While an isolated TSRA
cannot be ruled out, the impacts from any TSRA tonight or early
Tuesday should be minimal. Stronger TSRA will be possible Tuesday
afternoon east of I-35, but should mostly stay east of all our TAF
sites. In addition, a surge of Gulf of Mexico moisture will bring
stratus to about the eastern 2/3 of Oklahoma Tuesday morning.
Clouds with somewhat higher bases will likely linger through the
afternoon along the northern border of Oklahoma, including KPNC.
Otherwise, expect a breezy day tomorrow, with winds gradually
turning from southerly to southwest, and in far western Oklahoma:
to west, and eventually northwest.
CmS
PREV DISCUSSION... /issued 359 PM CST Mon Nov 21 2016/
DISCUSSION...
The primary forecast concern is an approaching wave that is
expected to bring a chance of showers/storms tomorrow. Isentropic
ascent ahead of the approaching wave should result in at least
isolated showers/storms developing tonight. Various convective-
allowing (HRRR/HRRRX/4 KM NAM) and parameterized models (12 KM
NAM/GFS) have been consistent with this solution, which is
reasonable given the progged warm-air advection. Greatest ascent
will begin across west central Oklahoma and shift east-
northeastward into central/northern Oklahoma. No severe weather is
expected.
Low-level winds will slowly veer through the day tomorrow,
shifting the chance of showers/storms east of I-35 by afternoon.
Dry air advection/low relative humidity across parts of western
north Texas/southwest Oklahoma will result in elevated fire
weather conditions by tomorrow afternoon. A cold front will move
from northwest to southeast through tomorrow afternoon into the
evening.
Across southeast Oklahoma, the potential for strong to severe
thunderstorms tomorrow afternoon/evening along will be modulated
by the amount of available instability. Effective bulk shear >50
knots will be more than sufficient for severe storms; however,
MLCAPE of 500-750 J/kg is expected to temper the overall severe
threat. Currently, instability appears to be limited by the amount
of solar insolation due to low-level cloud cover. Therefore, the
mesoscale environment will be characterized by high shear/low
CAPE. The cold front will provide a mechanism for strong, linear
forcing. In the aforementioned environment, storms would be
capable of gusty winds/bowing segments and perhaps embedded QLCS
mesovortices (due to high 0-1 km shear in association with a low-
level jet) if there is sufficient instability.
Beyond tomorrow, relatively tranquil and seasonable weather is
expected through Saturday. Temperatures will generally be at or
slightly above average through the period. Near average
temperatures will be expected on Wednesday before warming up on
Thursday. There will be a dry cold front passage late Thursday
into Friday that will drop temperatures back near average for
Friday.
Another mid to upper level wave is expected Sunday into Monday;
however, the 21/12Z GFS and ECMWF are in disagreement with timing.
Currently, there is at least a low chance of showers across
eastern Oklahoma on Sunday with cooler temperatures expected on
Monday.
Mahale
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 50 71 42 61 / 20 30 10 0
Hobart OK 53 70 40 62 / 30 10 0 0
Wichita Falls TX 54 75 43 65 / 10 20 0 0
Gage OK 50 64 35 62 / 40 0 0 0
Ponca City OK 52 68 41 60 / 30 40 10 0
Durant OK 54 68 47 65 / 10 60 40 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
17/23
Area Forecast Discussion
National Weather Service La Crosse WI
309 AM CST Tue Nov 22 2016
.SHORT TERM...(Today through Wednesday night)
Issued at 309 AM CST Tue Nov 22 2016
Forecast remains very challenging this morning...dealing with storm
system impacting the area today through Wednesday. Main challenge
will be precipitation types with tricky vertical temperature profile.
As of 3 am...Water vapor imagery coupled with RAP 500mb height
analysis showing trough of low pressure moving northeast out of the
Colorado Rockies. Push of 850mb moisture transport/isentropic
upglide ahead of the trough was producing a band of rain and
rain/sleet mix out across southwestern MN through northern IA per
radar/surface obs.
Look for this band of precipitation to continue lifting northward
into areas mainly along/west of the Mississippi through the morning
hours. However, there is a lot of dry air to overcome as it moves
northeast...so not sure how extensive precipitation will be. That
being said, latest forecast vertical temperature profiles indicate
precipitation type could be tricky as it rotates through with a
wintry mix of snow/rain/sleet and even some patchy freezing rain
where surface temperatures are cold enough...all possible. Will keep
a close eye on this and its impact on morning commute.
Mid-level trough and deepening surface low lifts through the Central
Plains toward the region this afternoon into tonight...increasing
moisture transport/broad isentropic lift into our area for
progressively heavier precipitation. Again, forecast thermal
profiles are a bit tricky...with realized surface precipitation
riding on surface temperatures and precipitation rates. Appears areas
south of I-90 will see mainly rain with a wintry mix along I-
90...and mostly snow north of I-94. Expecting 1-2 inches of snowfall
across Clark/Taylor counties tonight. Mid-level trough/surface low
continue to move east through the region Wednesday...with
precipitation winding down from west to east through the afternoon.
Could see another inch of snowfall across Clark/Taylor counties for
a total of 2-3 inches for the event. As such, have hoisted a Winter
Weather Advisory for Clark/Taylor counties from 6 pm this evening
through 6 pm Wednesday. Will have the dayshift keep an eye on
surface temperatures today/potential for mixy/freezing precipitation
types between the I-90/94 corridors which may warrant an Advisory as
well.
Precipitation looks to diminish rapidly Wednesday evening as the
trough/low pulls toward the Great Lakes Region.
.LONG TERM...(Thursday through Monday)
Issued at 309 AM CST Tue Nov 22 2016
Thanksgiving Day looks to be mostly cloudy with stratus trapped
under a subsidence inversion as surface ridge of high pressure
builds in from the Plains. Plan on highs in the 35-40 degree range.
There will be the potential for some light snow Thursday night as
another mid-level trough moves out of the Plains and across the
Upper Mississippi River region.
Looks dry from Friday through Saturday night as a ridge of high
pressure drifts across the region. High temperatures Friday will be
right around normal in the middle 30s/lower 40s, and then a bit
above normal Saturday topping off in the upper 30s to the upper 40s.
A good chance of precipitation returns Sunday afternoon through
Monday as low pressure tracks out of the Rockies and across the
region. Confidence on precipitation type is a bit low at this point
due to the uncertain track of this system.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1128 PM CST Mon Nov 21 2016
The ridge of high pressure was still holding tight and providing VFR
conditions and these will continue through the night. An area of low
pressure over eastern Colorado will move east/northeast into eastern
Kansas through Tuesday evening. A trough of low pressure extending
north from the low will move into southwest Minnesota as well. As a
short wave trough comes out of the Rockies it will interact with
these two features to cause precipitation to develop Tuesday
afternoon and continue into the evening. Thermal profiles from the
22.00Z NAM and GFS indicate this precipitation could be a mix of
rain and snow at KRST for much of the period while starting out as
rain before becoming a rain/snow mix at KLSE. Further complicating
the picture is the potential loss of ice Tuesday evening which could
lead to rain or freezing rain occurring. For now, have not included
this in either forecast but this may have to be introduced with
later forecasts if the model trends continue to support this.
Ceilings and visibility should come down to MVFR shortly after the
precipitation starts and expecting KRST to go to IFR ceilings.
Another concern is whether any light precipitation will develop
Tuesday morning. Some of the models have been showing a short 1 to 2
hour period of some light snow as a wing of warm air advection
swings across the area.
Confidence is not high in this occurring so have not included this
for now.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 6 PM this evening to 6 PM CST
Wednesday for WIZ017-029.
MN...None.
IA...None.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...04
Area Forecast Discussion
National Weather Service Denver/Boulder CO
916 PM MST Mon Nov 21 2016
.UPDATE...
Issued at 915 PM MST Mon Nov 21 2016
00Z models have come in with an increase in expected moisture,
especially over the time frame of 12z-18z tomorrow morning. Models
have slowed the trough`s progression as well, matching what is
currently occuring, which will be helping with the increase in
precipitation later. Have trended the forecast this way, with
increasing PoPs and QPF/Snow amounts over the urban corridor and
eastern plains. NAM forecast is way over blown with snowfall
forecasts over a foot for the eastern plains - likley convective
feedback. Could be some convection in the morning, but not
expecting these large values. Expect rain to change over to snow
over the metro areas and eastern plains right around sunrise
tomorrow...meaning the morning commute will be affected. However,
temperatures are still not expected to be very cold so snowfall
should remain slushy over the plains.
Winter Weather Advisory still looks good for the high country, for
5 to 10 inches to fall over the high mountains.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 227 PM MST Mon Nov 21 2016
Satellite imagery showing the center of the upper level trough is
moving into the Great Basin and Desert Southwest. It will
continue track east-northeast tonight and Tuesday. Scattered
showers are expected to spread east into the central and north
central mountains later this afternoon and evening. Latest HRRR
and RAP has backed off on the amount of showers, but still show
some. A few locations may see a quick inch or two snow if a heavy
snow shower passes over.
Snow should become widespread over the mountains around midnight as
the trough tracks over Colorado. Rain showers are expected to move
onto the Front Range and eastern plains shortly after midnight.
Airmass will be warm enough that precipitation will begin as rain at
the lower elevations. Eventually colder air moves in and a rain/snow
mix is expected around 12z with a brief period snow possible as
well. A heavier band of precipitation is expected to form on the
back side of the low Tuesday morning. Precipitation may turn to all
snow under this band with a few inches possible. Most of the GFS
ensemble members and ECMWF has this band to the east of the forecast
area. Will go with snow accumulation of around an inch over parts of
the eastern plains for this.
A moist northwest flow over the mountains is expected to keep snow
going through the morning. Most of the snow accumulation could occur
late tonight and Tuesday morning. Will keep the Winter Weather
Advisory in effect through Tuesday afternoon. As drier air moves in,
snow will decrease Tuesday afternoon. Precipitation will come to an
end mid to late morning along the Front Range as this system
continues to shift east. The precipitation may linger into the
early afternoon across the eastern plains.
.LONG TERM...(Tuesday night through Monday)
Issued at 227 PM MST Mon Nov 21 2016
Moisture and large scale forcing quickly diminishes Tue eve as
the upper trough moves out over the central Great Plains. Brisk
n-nwly deep layer flow and cold air advection continue overnight
giving us a colder night...although min temps by morning still
near to slightly above avg for the date. on Wed...an upper air
ridge is progged to pass over the region returning dry and warmer
conditions. Projected max temps on wednesday 1-3 deg c above
average with lower 50s on the plains with plenty of sunshine.
Warmup on the plains also aided by a warm sly breeze for much of
the day. by Wed night...models show the bottom side of an open
mid-level shortwave trough brushing over northern Colorado. system
appears wetter and more amplified on the GFS and DGEX...while the
Canadian model keeps the bulk of the moisture and energy with
this system up over Wyoming. Because of the most certain jump in
high country travel for the holiday...will trend the Wed night/Thu
fcsts towards the wetter/snowier GFS and DGEX and go with likely
pops over the higher elevations. By Thu afternoon could see
anywhere from 2-5 inches in the mtns...with high amounts on the
north and west slopes. However...the Park Range roughly north of
Rabbit Ears pass could possibly see totals approaching 8 inches on
a localized basis. There will be some wind...but with relatively
warm temperatures...do not see much in the way of blowing snow.
Most models show the wave swinging out over the plains
Thanksgiving Day with little more than a few light rain or
rain/snow showers across the nern corner of the CWA. Nwly flow
downsloping off the Front Range should hinder the formation of
precip within the urban corridor...except perhaps up near the
Wyoming border in the morning where any qpf should be minor at
best.
Thursday night through Saturday morning models show the forecast
area under the drying and warming effects of a flat upper
ridge. Should see slight warming both days with highs anywhere
from 4-7 degs above average. FYI...avg high at Denver during this
period is around 47.
Sunday and beyond...forecast less certain with model guidance
offering different times for the passage of another upper trough.
European model shows the trough and its precip over our eastern
border by Sunday morning. The GFS...DGEX and Canadian models show
the trough just arriving in western Colorado by that time. The
GFS and DGEX swinging this system across the state during the day
and out of the state by late that evening. Unfortunately the
Canadian model does go out that far. However...the European model
races another wave down across the nern Great Basin on Sunday...
and then across Colorado Sunday night and Monday. Because of the
uncertainly in the models out that far...will go with low pops for
Sunday/Sunday night and no pops for Monday...at least for now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 915 PM MST Mon Nov 21 2016
A surface low deepening over southeast Colorado has caused winds
to turn northwesterly. Northerly winds will continue tonight and
through Tuesday. Gusts up to 30 knots will be possible Tuesday
morning. Scattered rain showers will be possible after 06z. This
could briefly drop ceilings to 6000 feet. Showers will increase
and become more stratiform between 10-15z, with rain mixing with
and likely changing over to snow around or after 14z, decreasing
ceilings to 1000-2000 feet. Right now it appears snow
accumulation will generally around an inch, but it will be slushy.
Ceilings could fall below 1000 feet with visibility less than a
mile for a brief period. Conditions will start to improve around
18z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST Tuesday for COZ031-033-
034.
&&
$$
UPDATE...Kriederman
SHORT TERM...Meier
LONG TERM...Baker
AVIATION...Kriederman
Area Forecast Discussion
National Weather Service Cheyenne WY
1059 PM MST Mon Nov 21 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 245 PM MST Mon Nov 21 2016
Well-defined shortwave trof spinning nr UT/AZ stateline early this
afternoon with unseasonably strong fetch of sub-tropical moisture
advecting north ahead of it. Have recently even observed lightning
strikes over SE Utah with this feature as well. This disturbance was
the main forecast challenge and primary forecast focus today. Latest
model solutions have trended more similar in overall evolution...but
differences remain. Models are consistent in tracking this shortwave
east thru the four corners this evening, turning northeast towards
Kansas/Nebraska on Tuesday. Initial forcing and moisture to arrive
into Carbon/Albany Counties by sunset. The air mass has been
relatively warm today, so expect snow-levels of 8500-9000 feet at
around sunset to gradually descend to valley floors west of the
Laramie Range thru the evening hours. The p-type transition timing
will have impacts on eventual snowfall accumulations over lower
elevations of Carbon/Albany counties. Have steered the forecast
towards an early/mid-evening transition given the warm temps ahead
of the system along with ample moisture advection which will slow
cooling to wet-bulb 0 in llvls. Latest NAM guidance is the outlier
when it comes to precip amounts across these areas and was
discounted from this forecast. That said, lower elevations west of
the Laramie Range can expect widespread 1-3 inches with upwards of 5
inches possible in the Arlington area due to favorable northerly
upslope. The Snowy/Sierra Madre Ranges will fare the best with 6-12
inches anticipated. Latest guidance have trended down in precip
guidance for the ern plains with this system, with less than a tenth
of an inch of liquid progd. This would yield perhaps just a dusting
up to an inch in spots. P-type transition will likely not occur
until around midnight given the slow arrival for colder air mass.
Inherited highlights capture these expected conditions well, so no
changes necessary there. Any lingering light snow will dissipate
Tuesday morning, ending by around midday for everywhere except the
mountains. Otherwise, a blustery day for Tuesday over the ern plains
with northwest wind gusts that will reach 30-40 mph. High temps will
only reach the 30s to low 40s Tuesday.
Large scale subsidence associated with transitory shortwave ridging
will yield dry conditions Tuesday night and Wednesday along with
some wk llvl warm air advection. Breezy conditions return west of
the Laramie Range for Wednesday.
.LONG TERM...(Wednesday night through Monday)
Issued at 245 PM MST Mon Nov 21 2016
Somewhat unsettled weather seen across the CWA this period in a
rather progressive pattern with several shortwaves moving across
the region. Next wave scoots across Thursday bringing some snow
showers to mainly the mtns into east-central WY...clearing out
Thursday afternoon. Transient upper ridge passes over Thursday
night into Friday resulting in dry and warmer weather which will
continue into Saturday. Next shortwave approaches the CWA late
Saturday bringing another round of snow showers again mainly to
the mtns as well as a push of colder air. Sunday and Monday
looking cool with snow showers continuing over the mtns as the
upper flow becomes broadly cyclonic over the western and central
part of the country.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1043 PM MST Mon Nov 21 2016
Latest radar loop was showing bands of snow showers moving through
southeast Wyoming. Not seeing much in the way of intense bands of
snow at this point, but the HRRR is picking up more of an increase
in coverage and intensity of these bands of showers transversing
across southeast Wyoming as we approach daybreak. However, the
Local WRF is not showing much change in the areal of coverage and
intensity overnight. Based on the current IR loop we are seeing
more in the way of increased snowfall near the Northern Laramie
Range and southwest Carbon county. We will continue to monitor
these trends overnight and lean more towards the HRRR solution at
this point. This will result in IFR conditions developing as the
night wears on mainly in the southeast Wyoming TAF sites with LIFR
potential in the intense snowbands.
&&
.FIRE WEATHER...
Issued at 245 AM MST Mon Nov 21 2016
No fire Weather concerns this week with cool temperatures and a good
chance for precipitation today through Tuesday as another Pacific
storm system will move into the central Rockys. More snow is
possible by the end of this week with relative humidities remaining
moderate to high.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until noon MST Tuesday for WYZ112-114.
Winter Weather Advisory until 9 AM MST Tuesday for WYZ110-116.
NE...None.
&&
$$
SHORT TERM...CAH
LONG TERM...RE
AVIATION...REC
FIRE WEATHER...CAH/TJT
Area Forecast Discussion
National Weather Service Duluth MN
330 AM CST Tue Nov 22 2016
.SHORT TERM...(Today through Wednesday)
Issued at 301 AM CST Tue Nov 22 2016
Mid-level shortwave trough and associated sfc low pressure looks to
develop out of the Intermountain West states and translate northeast
across Kansas and Iowa. Models are showing that the center of the
low pressure will stay to the south of the forecast area, but an
inverted sfc trough with enhanced 850-700 mb Q-vector convergence
will move through the area. This should support snow across the
Northland, mainly starting Tuesday afternoon and continuing through
the day Wednesday. Storm total snow amounts are expected to be
between 2 to 4 inches, with some possibly reaching up to 5 inches
along the northern shore of Lake Superior. While this area was hit
pretty hard by the previous snowstorm, northwestern Wisconsin was
primarily spared from the snow of the previous system. With this
being northwestern Wisconsin`s first big taste of snowfall this
season, we issued a Winter Weather Advisory from Pine and Douglas
county, and all counties to the east across our forecast area.
Snowfall chances ramp up Tuesday evening and persist through
Wednesday morning. High temperatures are expected to be in the
lower to mid 30s across the area, with lows dipping to near 30
degrees Wednesday morning. Winds look to stay from the southeast
direction through Wednesday morning before turning to a more
east/northeast direction Wednesday afternoon.
.LONG TERM...(Wednesday night through Monday)
Issued at 301 AM CST Tue Nov 22 2016
A closed upper low is located in northwest Ontario Wednesday night,
while the surface low center moves into southern lower Michigan and
fills. An inverted surface trof remains in the vicinity of northwest
Wisconsin. A short wave trof also moves through the forecast area.
These features combine to warrant highest pops in the vicinity of
the surface trof Wednesday evening, trending downward overnight as
the best forcing from the upper trof moves east of the area. A
longer wave trof arrives on Thursday underneath the Ontario upper
low. Meanwhile, the surface trof lingers nearby due to a lack of
an upstream kicker to move it away from the region. There is just
enough forcing near the trof to keep some pops along the
international border into northwest Wisconsin. Timing issues begin
to show up in the models handling of a surface low center and its
affect on the area. Have some small pops in the Brainerd Lakes
region in the afternoon. A stronger, digging upper level trof
replaces the aforementioned one Thursday night as a weak surface
low center passes into eastern Lake Superior. Models disagree a
bit on overall coverage and location of highest QPF. Also, a wedge
of dry air from high pressure building into the Dakotas may eat
away at some of the moisture and affect QPF. Used a blend for pops
Thursday night. On Friday, the upper trof moves east of the area.
However, there is some channeled vorticity right behind it. Before
the surface trof departs, this will be the focus for some
additional precipitation in the morning. Dry high pressure takes
over Friday afternoon. Upper level ridging covers the region
Friday night through Sunday morning. Even though the surface high
moves east of the area, a warm and dry southwest flow sets up and
have removed the mention of precipitation. Models disagree on the
handling of the next potential winter storm to affect the area
Sunday afternoon through Monday. With these differences, used a
blend of pops.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1153 PM CST Mon Nov 21 2016
A ridge of high pressure will continue sliding eastward overnight
into the Central Great Lakes by Tuesday morning. Behind the high,
the combination of warm air advection and a trough lifting into
Manitoba will gradually increase mid to high level clouds from
west to east into Tuesday morning. Will see light snow gradually
spread into the Northland from west to east on Tuesday. This will
bring ceilings and visibilities down from VFR to IFR and
potentially LIFR at some locations per the NAM/GFS/DLHWRF and RAP
as the TAF period progresses. Most confident in LIFR ceilings at
KBRD, but think LIFR visibilities will hold off per MOS guidance
and the GFSLAMP.
Still uncertain on the potential for freezing drizzle at KBRD
Tuesday morning between 12Z and 14Z. The majority of model soundings
show this setting up, but unsure if saturation in the lower levels
will occur as quickly as models suggest. After 14Z any mixed
precipitation will change over to all snow.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 33 31 34 28 / 70 90 70 30
INL 33 29 34 26 / 70 80 70 30
BRD 32 31 34 27 / 80 90 50 10
HYR 35 32 35 28 / 40 90 70 30
ASX 37 32 36 29 / 40 80 80 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 3 PM this afternoon to 3 PM CST
Wednesday for WIZ001-002-006-007.
Winter Weather Advisory from 6 PM this evening to 6 PM CST
Wednesday for WIZ003-004-008-009.
MN...Winter Weather Advisory from 3 PM this afternoon to 3 PM CST
Wednesday for MNZ038.
LS...None.
&&
$$
SHORT TERM...JTS
LONG TERM...GSF
AVIATION...WL
Area Forecast Discussion
National Weather Service Green Bay WI
1042 PM CST Mon Nov 21 2016
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 212 PM CST Mon Nov 21 2016
Quiet conditions to continue across northeast WI for about another
24-30 hours as a ridge of high pressure slowly moves across the
Great Lakes. Main forecast issue to again be on temperatures
tonight as evening clear skies become mostly cloudy by daybreak
as high clouds overspread the region. A secondary concern has to
do with the timing of the leading edge of precipitation late on
Tuesday, but it now appears that most of the precipitation will
hold off until after sunset across central WI.
The 20z MSAS surface analysis showed the ridge of high pressure
extended from western Ontario south through the Great Lakes to the
TN Valley. Visible satellite imagery had picked up on the high
clouds overspreading the northern Plains/Midwest with mid-clouds
over the central Plains. Current temperatures were near normal
values for late-November.
The surface ridge axis will continue to slowly drift east tonight
due to blocking system located over the Canadian maritimes.
Meanwhile, the system of interest is forecast to move across the
central/southern Rockies with southerly winds in advance of the
developing surface low to begin tapping gulf moisture. For
northeast WI, look for high clouds to start overspreading the area
during the overnight hours, but with winds being light/variable,
temperatures could still tank across northern WI where there is
snow on the ground. Latest thinking would be to have mins range
from 10 to 15 above north, upper teens to lower 20s east-central
WI.
As the surface ridge slides farther east and the system pulls into
the central Plains on Tuesday, main question for the day will be
where the leading edge of precipitation be located? The air mass
over eastern WI appears to be rather dry at the onset, so much of
the advancing precipitation could simply go into saturation. The
NAM remains the slowest of the models with the leading edge of
precipitation just reaching western WI by 00z Wednesday. The GFS
has slowed a bit with the leading edge reaching central WI by late
in the day. Other models end up somewhere in between. Bottom line
here is that eastern WI will remain dry through Tuesday with only
a small chance pop for central WI later Tuesday afternoon. Any
precipitation that reaches north-central WI would fall as all snow
with temperatures in the lower 30s. However, central WI could be
in for a rain/snow mix (probably more rain than snow) with
temperatures in the middle to upper 30s. Eastern WI will be the
warmest with max temperatures in the upper 30s to around 40
degrees.
.LONG TERM...Tuesday Night Through Monday
Issued at 212 PM CST Mon Nov 21 2016
A rather active period this week as well as through next weekend
with a series of troughs passing over the Upper Midwest and
Western Great Lakes region nearly every other day. Lack of
widespread cold air in the region providing a mix potential for
the systems impacting the area.
First storm to deal with is the Tuesday night into Wednesday
night system. Nearly elongated surface to 850 mb lows are progged
to slide over the region. Many issues linger with this storm
system, with the arrival the first problem. A nearly stalled
stacked low centered over Maine and an upper ridge just to the
west likely will delay the arrival of the pcpn into Tuesday
evening. The GFS continues to be the quickest with the arrival
Tuesday afternoon, otherwise a blend of the remainder of the runs
suggests tuesday evening arrival time. Another issue with the
system is the snow ratios. H7 temps warmer than -10 c suggest a
limited snow growth region and forecast soundings indicating a
rain and snow mix for most locations, and mainly snow north
central. Did consider a watch for NC Wisconsin for Tuesday night
into Wednesday evening due to impact with holiday travel, but the
snow ratios with the anticipated pcpn suggests more of a long
duration advisory. Due note that some northern stream energy
drops into the northern Great Lakes later Wednesday into Wednesday
night which could further slow down the system and prolong the
accumulating snow.
With a light pressure gradient and a more compact type of snow
factoring into lesser amounts, will hold off any headlines for
now and let later shifts post advisories as needed. At this time
anticipate mainly 3 to 7 inches of snow over a 36 hour period
north of a Wausau to Wausaukee line, 1 to 3 inches just south of
this line and around and inch mixed with rain toward East Central
Wisconsin.
A quieter day is expected Thanksgiving day as a ridge of high
pressure quickly passes over the region.
A weaker system will bring a chance of mainly snow to the area
late Thursday night into Friday. The latest GFS trended further
north with a band of 1 to 2 inches of snow.
For what its worth, medium range progs then go into a series of
deeper low pressure systems starting late Sunday into next week.
ECMWF and GFS lift a deeper low into the region Sunday into
monday with timing an issue. Height 850 temps a little warmer
rising to +5 C by Sunday night over East Central Wisconsin but
cooler to the west for a mix again.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1039 PM CST Mon Nov 21 2016
High and then middle clouds ahead of the next system will
gradually overspread the area overnight and tomorrow morning.
Still some question about the possibility of lake clouds
spreading back into eastern Wisconsin as the low-level flow
swings around to the east. Not much sign of this happening yet on
satellite imagery, but the RAP indicates it may take until
morning. Will stay the course with the 06Z TAFs and bring MVFR
cloud deck to the east-central TAF sites tomorrow morning.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....Kallas
LONG TERM......TDH
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service North Platte NE
335 AM CST Tue Nov 22 2016
.SHORT TERM...(Today and tonight)
Issued at 328 AM CST Tue Nov 22 2016
Today and Tonight...the upper low across Northern NM lifts
northeast today and tonight. Plenty of moisture across Cntl Neb
with precipitable water over 0.75 inches in the RAP model and
ample theta- e in the 850-700mb layers feeding into an h700mb low
which should track east across Wcntl KS and then northeast through
eastern Neb. This is a little south and east of our most favored
track which is Nrn KS through Cntl Neb.
The ECM...RAP...GFS...NMM and ARW were close with the more eastern
track and were the basis for a blended forecast. The NAM and SREF
were western and northern solns for QPF. The NAM...GFS and RAP show
strong lift in the -10C to -20C snow growth zone which could support
a rain snow mix during the peak lift today. We are expecting 0.25
inches or more of qpf in 6 hours across srn Neb this morning and
ncntl Neb this afternoon. The model consensus shows h700mb
temperatures around -3C which is not particularly favorable but a
mix might develop at times of strong lift. The rain and snow is
forced by an area of frontogenesis and deformation indicated in the
RAP40 model. The system should lift northeast of Ncntl Neb tonight.
The temperature forecast is a bias corrected blend of the
GFS...ECM...NAM and SREF for highs in the upper 30s to upper 40s.
Warmest highs occur across Northwest Neb where little or no rain is
expected. Lows tonight are a blend of bias corrected guidance for
lows in the 20s to lower 30s. Teens are possible across the Western
Sandhills.
.LONG TERM...(Wednesday through Monday)
Issued at 328 AM CST Tue Nov 22 2016
Shortwave ridging will build across the region Wednesday ahead of
the next system slated to cross the area Thanksgiving day. The
farther south ECMWF has trended north, and is now in line with the
GFS and NAM which tracks the system across South Dakota. This will
be a quick moving open wave, and only scattered light rain and snow
showers are expected, with most of the activity to remain north of
our area. Pops have been almost completely removed from our forecast
area.
More significant ridging aloft translates west to east across the
central portion of the country Friday and Saturday. This will bring
a warm up once again to the region, with highs all areas expected
to be in the 50s on Saturday.
Sunday and beyond are a bit up in the air, as the models diverge
Sunday. As energy (troughing) moves into the western portion of the
country, the ECMWF is much faster bringing the trough into the
central portions of the country on Sunday. In fact, it spins up a
fairly significant cyclone. The GFS hold the energy back to the west
until Monday, and brings a weaker upper level trough through the
area. Downstream ridging across the Atlantic next week, will help
maintain a trough across the central or western portions of the
country, keeping the weather unsettled. At this time no big storm
appears to be on the horizon, but the pattern could support some
sort of storm development, and will be watched closely.
Temperature wise expect a return to cooler weather as the
troughing takes shape.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1150 PM CST Mon Nov 21 2016
Multiple concerns in the aviation forecast period including
precipitation timing, precipitation type, winds, and
ceilings/visibility. Currently VFR ceilings and visibility are
observed across western and north central NEB with ceilings
reported between 8-12 kft. Earlier radar returns across north
central NEB from late this afternoon have moved northeastward out
of the area.
Aviation forecast was revised to some extent, specifically
delayed start of precipitation and removed precipitation from the
KVTN TAF. The best chances for precipitation will be present more
so tomorrow than tonight. Best chances tomorrow will lie from Big
Springs to south of KVTN southeast through southwest NEB and the
remainder of north central NEB. Generally quiet conditions are
expected rest of tonight along with a gradual lowering of
ceilings.
Tomorrow, likely rain and/or snow across the southwest half of
the forecast area. Some uncertainty associated with precipitation
type. Current thinking for the morning period is that the
rain/snow line will be located from Imperial to Stapleton to
Newport where there will be a transition to rain/snow or all snow.
A narrow band of moderate precipitation is expected to setup
tomorrow mid-late morning wherein the precipitation type is
expected to be primarily rain/snow or all snow. This band may
impact KLBF wherein KLBF could then see snow possibly more so
than a rain/snow mix, however, confidence is low. Will continue to
monitor this and refine the forecast. Precipitation is then
expected to transition back to rain in the afternoon. Strong
north to northwest winds are expected to develop tomorrow mid to
late morning with gusts up to 20 to 25 kts, strongest winds in
western NEB. Winds are expected to slowly diminish in the late
afternoon through tomorrow night.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...Taylor
AVIATION...ET
Area Forecast Discussion
National Weather Service Marquette MI
420 AM EST Tue Nov 22 2016
.SHORT TERM...(Today and tonight)
Issued at 359 AM EST TUE NOV 22 2016
00Z raobs/latest wv imagery and RAP analysis show a confluent nw
flow aloft over the Great Lks btwn slow moving deep closed lo near
Maine and an upr rdg extending fm the Upr MS River Valley into nw
Ontario. Sfc hi pres rdg stretching fm NW Ontario thru Upr MI and
into IL in concert with very dry air shown on the 00Z YPL/GRB raobs
/00Z pwat as lo as 0.15 inch at YPL and 0.19 inch at GRB/ are
bringing dry wx to the cwa early this mrng even as sct lk clds
linger over the e half of the cwa in persistent chilly nnw llvl flow
to the e of the hi pres rdg axis. Some hi clds are spreading over the
upr rdg axis into the wrn cwa well in advance of vigorous shrtwv
lifting out of upr troffing acrs the wrn CONUS and into the scentral
Plains. The combination of the dry air/lgt winds have allowed temps
to fall aob 10F over the interior w half.
Main concerns in the short term are on pops/expected sn accums tngt
as shrtwv/sfc lo/attendant warm fnt aprch fm the sw.
Today...Although hi/mid clds wl continue to overspread the area fm
the wsw, expected slow exit of sfc hi pres rdg/accompanying llvl dry
air wl keep the cwa dry except for perhaps far wrn Lk Sup. Despite
the chilly start, expect hi temps to rebound to arnd 32.
Tngt...With larger scale waa/isentropic ascent dvlpg over the area
tngt, expect thickening clds and at least some lgt pcpn to spread
into portions of the cwa. There are some sharp model differences on
how far/fast to the ne this pcpn wl arrive. Given the sluggish
deep closed lo near Maine, models have trended a bit slower on moving
hi pres rdg now dominating the Upr Lks to the e. Given the more
tenacious hi pres rdg/accompanying llvl dry air, opted to hedge
toward the slower guidance on bringing accompanying pcpn to the e,
especially because the sharper isentropic ascent/deep lyr qvector
cnvgc/upr dvgc are progged to remain to the s of Upr MI. Tended
toward the lower qpf as well. Fcst h85 temps blo 0C, lingering llvl
dry air, and nocturnal cooling sug sn should be the predominant
ptype expect perhaps near the llvl warming influence of the Great
Lks. Considering all the negatives for sgnft pcpn, the fcst for tngt
wl feature no more than about an inch of sn over the far w.
.LONG TERM...(Wednesday through Monday)
Issued at 417 AM EST TUE NOV 22 2016
Shortwave trough over the middle conus will be main instigator of
the snow moving over western Upper Michigan on Wed morning. Sfc low
tied to the shortwave will be crossing northern half of IL by Wed
aftn which is slower and slightly farther south than what has been
shown in last couple days. Unless something changes significantly in
models, trend is not good for seeing advy level snow over much of
Upper Michigan. Only exception is in the far southwest cwa and even
here qpf and resultant snowfall has trended lower as well. Main
reason for downward trend is resilient high pressure ridge and dry
low level air. Ridge is in place due to confluent nw flow aloft btwn
upper ridge moving across the Great Lakes and strong upper low over
northeast conus.
Eventually on Wed soundings show dry air will be overcome as
shortwave trough crosses the western Great Lakes. Trough comes in
pieces though as shown by spread out deep layer q-vector convergence
from Ohio Valley north into Upper Great Lakes. Strongest area of mid
level q-vector convergence stays south of Upper Michigan while there
is a bit more h85-h7 q-vector convergence as weakening h85 low
tracks toward northern WI on Wed aftn. Isentropic ascent on 290-295k
sfcs is broad and weak which matches modeled weak omega/lift as
well. Overall seems that lack of focused ascent and minimal
enhancing upper level divergence will work against seeing widespread
moderate precip compared to how is looked a couple days ago. In
terms of how much snow could occur, soundings indicate dgz will be
very elevated in narrow layer above 12kft so SLRs will likely remain
blo 10:1 which will ultimately hold down snow amounts but also leads
to wetter/heavier snow.
So even though this snow will fall on very busy travel day before
Thanksgiving, do not have enough confidence that trends will not
continue to show lesser and lesser precip/snow over time. Latest
snowfall projections of mainly 1-2 inches Wed and again Wed night
struggle to come close to what is needed for advisory 2-4 inches/12
hr for wetter snow. Will keep an SPS going to highlight the light
but wetter snow for the busy travel day but will not be issuing
advisory. Better signal that heavier snow will fall to the southwest
across northern WI so adjacent NWS offices in DLH and GRB have issued
an advisory this morning for those areas. Dayshift can take another
look at it to see if trends reverse at all to see if advisory would
be needed in parts of our cwa.
Later Wed night into Thanksgiving deep moisture departs and could
see some drizzle, especially west and scntrl. OTherwise will be
patchy light rain or snow. Only light snow accumulations would be
over far east cwa in the morning and perhaps the higher terrain of
the Keweenaw with east wind off Lk Superior. h85 temps down around
-4c so there is limited over water instability. WBzero heights will
be borderline for rain/snow though especially near sfc as temps
rise into the mid 30s.
Another shortwave zips across western Great Lakes late Thu night
into Fri morning. Pops have increased and could see need for likely
pops eventually. High pop and low qpf setup with any snow amounts
staying under an inch.
Break in wx still in there for later Sat into Sun, then differences
develop in models in how quick and strong to bring out next low
pressure system for Sun and Mon. ECMWF faster while GFS is slower.
Blend of two along with GEM would suggest mix of rain/snow moving in
later Sun into Mon. Winds may be gusty depending on how deep the low
is as it lifts across the region. Still a bunch of time to sort out
those details. Overall pattern looks like it will remain active for
much of next week with chances for snow or mixed rain and snow.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1126 PM EST MON NOV 21 2016
High pressure will slowly shift east, only reaching central Upper MI
by early Tue aftn. VFR conditions will prevail at KIWD thru most of
this fcst period until light snow and MVFR conditions move in by Tue
evening. KCMX will also be VFR thru the fcst period, but as the
ridge shifts e of the terminal, developing ese wind off Lake
Superior could lead to a brief period of bkn MVFR cigs mid to late
Tue morning. At KSAW, bkn MVFR cigs could occur at times overnight
as light upslope n to ne winds continue until the high pressure
ridge arrives late Tue morning.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 359 AM EST TUE NOV 22 2016
As a hi pres ridge extending s across western Lake Superior drifts
e, reaching eastern Lake Superior this aftn, lingering 20kt winds
over eastern Lake Superior will diminish this morning and fall below
15kt the rest of the day. Over the w half of the lake, light winds
under 15 kts will become se and increase up to 20kts under the
tightening pres gradient between the slowly departing hi and lo pres
moving newd from the central Plains. As the ridge shifts e and the
lo pres system over the Plains moves toward southern Lake Michigan
late on Wed, ese winds will increase up to 20-25kt across much of
the lake on Wed, with the strongest winds occurring over central and
eastern Lake Superior. Winds will then diminish to under 20kt for
Thu-Sat as the pres gradient across the area becomes relatively weak.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...07
MARINE...KC
Area Forecast Discussion
National Weather Service La Crosse WI
538 AM CST Tue Nov 22 2016
.SHORT TERM...(Today through Wednesday night)
Issued at 309 AM CST Tue Nov 22 2016
Forecast remains very challenging this morning...dealing with storm
system impacting the area today through Wednesday. Main challenge
will be precipitation types with tricky vertical temperature profile.
As of 3 am...Water vapor imagery coupled with RAP 500mb height
analysis showing trough of low pressure moving northeast out of the
Colorado Rockies. Push of 850mb moisture transport/isentropic
upglide ahead of the trough was producing a band of rain and
rain/sleet mix out across southwestern MN through northern IA per
radar/surface obs.
Look for this band of precipitation to continue lifting northward
into areas mainly along/west of the Mississippi through the morning
hours. However, there is a lot of dry air to overcome as it moves
northeast...so not sure how extensive precipitation will be. That
being said, latest forecast vertical temperature profiles indicate
precipitation type could be tricky as it rotates through with a
wintry mix of snow/rain/sleet and even some patchy freezing rain
where surface temperatures are cold enough...all possible. Will keep
a close eye on this and its impact on morning commute.
Mid-level trough and deepening surface low lifts through the Central
Plains toward the region this afternoon into tonight...increasing
moisture transport/broad isentropic lift into our area for
progressively heavier precipitation. Again, forecast thermal
profiles are a bit tricky...with realized surface precipitation
riding on surface temperatures and precipitation rates. Appears areas
south of I-90 will see mainly rain with a wintry mix along I-
90...and mostly snow north of I-94. Expecting 1-2 inches of snowfall
across Clark/Taylor counties tonight. Mid-level trough/surface low
continue to move east through the region Wednesday...with
precipitation winding down from west to east through the afternoon.
Could see another inch of snowfall across Clark/Taylor counties for
a total of 2-3 inches for the event. As such, have hoisted a Winter
Weather Advisory for Clark/Taylor counties from 6 pm this evening
through 6 pm Wednesday. Will have the dayshift keep an eye on
surface temperatures today/potential for mixy/freezing precipitation
types between the I-90/94 corridors which may warrant an Advisory as
well.
Precipitation looks to diminish rapidly Wednesday evening as the
trough/low pulls toward the Great Lakes Region.
.LONG TERM...(Thursday through Monday)
Issued at 309 AM CST Tue Nov 22 2016
Thanksgiving Day looks to be mostly cloudy with stratus trapped
under a subsidence inversion as surface ridge of high pressure
builds in from the Plains. Plan on highs in the 35-40 degree range.
There will be the potential for some light snow Thursday night as
another mid-level trough moves out of the Plains and across the
Upper Mississippi River region.
Looks dry from Friday through Saturday night as a ridge of high
pressure drifts across the region. High temperatures Friday will be
right around normal in the middle 30s/lower 40s, and then a bit
above normal Saturday topping off in the upper 30s to the upper 40s.
A good chance of precipitation returns Sunday afternoon through
Monday as low pressure tracks out of the Rockies and across the
region. Confidence on precipitation type is a bit low at this point
due to the uncertain track of this system.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 538 AM CST Tue Nov 22 2016
Tricky forecast when it comes to precipitation type, especially
for RST tonight. First things first, initial batch of
precipitation is working toward the area and will impact RST
roughly 13-16Z with a wintry mix of precip types but overall VFR
conditions. That batch of precip is expected to wane with eastward
extent, so no mention for LSE just yet. We should catch a brief
break into early afternoon before a more robust round of
precipitation arrives through late afternoon and evening. This
should be mostly rain for LSE (maybe some snow at the onset?) and
may briefly be more of a mix at RST before changing to mainly rain
as we lose ice in the clouds and develop a warm nose aloft.
However, surface temperatures will be key, as readings will likely
be in the 32-34F range, suggesting there is some small potential
for freezing rain. Confidence not nearly high enough in that
regard to include a mention of FZRA yet, but something to watch
very closely. Ceilings should tank down to IFR range through the
night, with winds mainly from the southeast becoming gusty 20-25
knots today, especially at RST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from 6 PM this evening to 6 PM CST
Wednesday for WIZ017-029.
MN...None.
IA...None.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...Lawrence
Area Forecast Discussion
National Weather Service Denver/Boulder CO
417 AM MST Tue Nov 22 2016
.SHORT TERM...(Today and tonight)
Issued at 417 AM MST Tue Nov 22 2016
Deformation band has developed on the northwest side of the
developing low. This is taking shape across the Front Range
cities, and is being amplified by upslope on the north side of the
Palmer Divide. HRRR has been pretty consistent with the location
of this feature, but precipitation amounts have been varying quite
a bit from run to run. Larger scale models appear to have this
feature too far east. The evening shift made adjustments in this
direction, so for this forecast package just a few changes needed.
I slowed down the departure of the band a couple more hours,
keeping some lower PoPs in the forecast over the western part of
the plains into the early afternoon. Also nudged up precipitation
just a little. Snow level still looks to be 7-8 thousand feet over
the Front Range with cooler air on the plains and a little cooling
coming in from the north. Rain has changed to snow at Rawlins,
Laramie, and Cheyenne, so the cooling expected to reach Denver by
mid morning is coming. It will still be hard to push the snow
level down to 5000 feet, and even if there is snow at that level
air temperatures above freezing and warm ground will limit the
impact. Main concern is not so much the amount of snow as the
timing. With both more precipitation and eventually colder
temperatures south and southeast of Denver, this area appears to
be the main threat. Went ahead and issued a Winter Weather
Advisory for the Monument Hill area which could see 1/2 to 1 inch
per hour snowfall rates during rush hour. Hopefully still warm
enough to mitigate the impact some there, but it could be a mess
for a few hours. Further east temperatures are also marginal.
Could be some snow and if it comes quick enough it could
accumulate on the grass, but little impact is expected.
Skies clear tonight with lingering light orographic snow over the
mountains ending. Slowed this down a couple hours as well given
the slower speed of the system.
.LONG TERM...(Wednesday through Monday)
Issued at 417 AM MST Tue Nov 22 2016
Models have an upper ridge over the CWA on Wednesday with strong
and increasing westerly flow aloft through the day. There is a
southwesterly jet maximum across the forecast area Wednesday
night. A weak upper trough is progged to move eastward across the
forecast area Thursday morning into mid afternoon. The zonal flow
decreases a bit Thursday afternoon as an upper ridge gets into
Colorado Thursday night into Friday. Weak downward energy is
progged on the QG Omega fields Wednesday morning, then upward
vertical velocity is over the CWA Wednesday afternoon well into
the evening. Late Wednesday night, strong downward motion moves
in. The synoptic scale energy remains downward Thursday and
Thursday night but it weakens through that time frame. South-
southwesterly low level winds are progged Wednesday. Downsloping
westerly and northwesterly winds are progged Wednesday night,
with fairly strong northwesterlies on Thursday. Drainage winds
kick in by mid evening Thursday night. For moisture, there is not
much Wednesday, maybe a tad in the upper levels. Moisture
increases in the mountains Wednesday night. There is a brief shot
and it is not very deep on any of the models. By Thursday mid-
morning it gets quite dry for all the CWA, and that continues into
the extended period. The QPF fields have no measurable
precipitation over the CWA Wednesday, then there is some Wednesday
night into Thursday morning for the mountains only. There is none
after that for all the CWA. For pops, will go with 30-60%s for
the high mountains Wednesday night/early Thursday morning. There
is moisture, some upward energy and some decent orographic
enhancement only after 06Z. The winds will be pretty strong above
10,000 too. It is brief and snowfall amounts will likely be under
5 inches total anywhere. For temperatures, Wednesday`s highs will
be 1.5-4.0 C warmer than today`s highs. Thursday`s highs will cool
down 2-5 C from Wednesday`s. For the later days, Friday through
Monday, there is upper ridging to move across Colorado on Friday,
then pretty strong west-southwesterly flow aloft on Saturday. By
Sunday the ECMWF and GFS develop a mean upper trough over western
North America. It continues on Monday as well. The specifics
between the two models still differ considerably, but at least
they are now both showing a somewhat similar synoptic pattern. The
GFS has more precipitation on Sunday night and Monday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 417 AM MST Tue Nov 22 2016
An area of rain has developed over Denver and with temperatures
cooling a bit it will mix with or change to snow this morning. A
period of IFR conditions is likely between 13z and 18z. There is a
chance of LIFR conditions for a couple of hours in moderate
snowfall. With warm temperatures runway accumulations are
unlikely, but an inch or two of snow is possible on the grass.
The lower conditions and snow accumualation are most likely at
KAPA and least likely at KBJC. Conditions should improve quickly
between 18z and 20z with VFR conditions expected after that.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 PM MST this afternoon for COZ031-
033-034.
Winter Weather Advisory until 11 AM MST this morning for COZ041.
&&
$$
SHORT TERM...Gimmestad
LONG TERM...RJK
AVIATION...Gimmestad
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
936 AM CST Tue Nov 22 2016
.UPDATE...
Issued at 936 AM CST Tue Nov 22 2016
Have sent out a recent update to reflect latest precipitation
trends, mainly increasing pops this morning and trying to show
possibility of a brief break in the precipitation this afternoon
across the south. Liked the trends on the 13Z HRRR output, so
modeled the pops after that solution with some modifications.
Majority of the precip has changed to all rain across the north,
with a few pockets of fzra still possible even with sfc temps near
or above freezing dew to lower dewpoints/wetbulb temps below
freezing. Otherwise as dewpoints increase in the next hour or two
Mason City and the far north, expect all precip to switch over to
rain. Little icing on roads occurring attm with the road temps
still showing temps in the mid 30s there as well.
&&
.SHORT TERM.../Today through Tonight/
Issued at 349 AM CST Tue Nov 22 2016
Confidence Medium to High
Models in good agreement on timing details today and tonight.
First push of warm air advection precipitation entering southern MN
and northern Iowa. So far any mix has been limited to far northwest
counties near Estherville. Warm air advection is compensating for
lower wet bulb temperatures so far...as light precipitation
continues across the north. The far north this morning through
about 8 am may still see brief light freezing rain and a very light
ice accumulation but not expecting too many impacts as road
temperatures have been reported to be just above freezing at 34-
35F...but may drop a bit toward sunrise. As the low moves east
across Kansas by midday...stronger warm air advection and rain and
showers will increase over the region during the day. As the low
nears northern Missouri tonight rain and a chance of thunderstorms
will increase across the south half this afternoon into the evening
hours. Later in the evening the warm sector will shift enough east
that instability will decrease with thunder chances ending and rain
remaining. Highs today will reach the the mid 30s north to the lower
to mid 40s south. Tonight lows will slowly fall behind the low with
clouds and sufficient mixing. Temperatures aloft suggest that the
rain will mix with light snow north/northwest as colder air returns.
Though a rain/snow mix is anticipated to change over to light snow
the better forcing will have moved east and light precipitation
amounts coupled with lessening chances for precipitation should only
yield a light dusting on grassy areas if any. Northwest winds will
pick up tonight with wind chills in the mid to upper 20s north and
in the 30s across the south.
.LONG TERM.../Wednesday through Monday/
Issued at 349 AM CST Tue Nov 22 2016
The pattern will certainly remain active through the period with two
windows of precip. At onset, the system currently approaching the MO
Valley will be on its way out with forcing just lingering into Wed
morning. This may result in some light rain, or possibly light snow
north, but with little if any accumulation as temps rebound after
daylight. Short wave ridging will then bring fair weather for the
remainder of Wednesday and into the start of Thanksgiving. However
the northeastern Pacific system now along 140W will eventually track
through the CONUS quickly increasing forcing by Thursday afternoon.
The preceding return flow will be brief and fairly weak so moisture
may be somewhat limited. The forcing will be deep however with
both thermodynamic and kinematic contributions but the southern
fringe may not be realized into the southern half of IA with
saturation more questionable. The models have come into better
agreement suggesting the best chances will be across northern IA
into MN. A blend of forecast soundings show a rain/snow mix
transitioning to all snow before ending. It will be moving fairly
quickly, only lasting 6-9 hours at most, but there could be a brief
burst of heavier snow with nice lift in the dendritic growth zone
around H6/H7. Its depth will be shallow though so with the
brevity and possibly some melting it should keep any
accumulations less than an inch at this point.
The next system looks to approach into early next week and could
potentially present some travel issues for the end of the holiday
weekend, especially north and west. Confidence has increased
somewhat in general timing with the ECMWF and GFS now showing
better run to run continuity than before, but there are still
plenty of differences and a lack of ensemble support, especially
from the ECMWF. The ECMWF is much stronger than the more open GFS
and temperatures are certainly not clear cut with critical values
splitting the state. Thus the system is currently nothing more
than something to keep an eye on at this point until details
become clearer. The current forecast has the precip ending by
Monday, but the ECMWF ensemble does suggest something a tad
slower.
The ECMWF and GFS deterministic runs and ensembles are in good
agreement into early next week with a large mean trough settling
into the central CONUS, but at this point the southern stream
seems more dominate with any sensible weather effects staying to
our south and east and the end of the extended forecast dry. This
pattern would also keep our temps seasonal through the period
until the northern stream becomes more active.
&&
.AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/
Issued at 536 AM CST Tue Nov 22 2016
With system approaching will be looking at lowering cigs with MVFR
16-18z west spreading east...then IFR conditions 00-02z west
overspreading the region through 12z Wed as VSBY will also lower
during the period to 2-5sm aft 00z. Rain will increase regionwide
aft 15z with iso thunder possible aft 21z southwest and then
through 05z south sites at KDSM and KOTM. With thunder coverage
rather light...confidence low as to specific timing and have left
mention out for now. Toward end of period may see changeover of
RASN affecting KMCW/KFOD 09-12z with return of northwest winds.
/rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...Beerends
SHORT TERM...REV
LONG TERM...Small
AVIATION...REV
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1027 AM EST Tue Nov 22 2016
.SYNOPSIS...
Dry high pressure will persist over the region through early
Wednesday as temperatures slowly moderate. A fast moving cold front
will cross the area Wednesday night with dry conditions returning on
Thursday. Another dry cold front is expected to move through the
area on Friday. Dry high pressure will set up once again over the
weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1025 AM: Waves of thin cirrus and contrails will continue to
drift across the forecast area through the rest of the morning. The
cloud cover has resulted in a slight decrease in the morning
warming. I will update the forecast to adjust sky and temp forecast.
As of 630 AM EST: IR satellite imagery continues to show a band of
thin, high clouds streaming over the upstream ridge axis in NW flow
aloft. Only minor adjustments to hourly temperature trends and sky
were needed with the latest update. Will continue to feature patchy
smoke near and immediately downwind of fires burning along and just
east of the escarpment. Otherwise, water vapor imagery and 500 mb
RAP height fields show a prominent trough moving eastward over the
southern plains while a downstream ridge moves quickly east of the
MS river valley. At lower levels, surface high pressure initially
over the Appalachians will move to the eastern seaboard through the
period - with the dry airmass slowly modifying. 850 mb flow will be
considerably weaker today than in days past, but with a weak
westerly downsloping component continuing. This should push maxes
above MOS this afternoon, with dewpoints drying out well below MOS
toward the bone dry HRRR/RAP guidance values.
The upper ridge axis will cross the forecast area tonight and permit
mid clouds east of the upstream trough to spill into the mountains
overnight. Any light precipitation ahead of the approaching cold
front overnight will stay west of the mountains through daybreak.
The coolest temperatures in the forecast area overnight should be
east of I-77.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
At 2 AM Tuesday: On Wednesday morning an upper ridge will extend
from the Southern Appalachians to the Great Lakes, while an upper
trough will be approaching the MS River Valley from the west. The
pattern progresses and deamplifies such that by Thursday morning the
upper trough reaches the East Coast, another low amplitude ridge
reaches MS River Valley, and a trough reaches the east slopes of the
Rockies. By Friday morning the upper ridge reaches the East Coast,
while the trough upstream reaches the MS River Valley.
At the surface, a ridge of high pressure will cross the Eastern
Seaboard on Wednesday, while a cold front moves from the MS River
Valley to the Southern Appalachians. As the pressure gradient ahead
of the front decreases, Gulf inflow declines, limiting the chance for
appreciable rainfall over our area. The front moves east of our
area by midday Thursday, followed by drying and weak high pressure
into Thursday night. Temperatures will rise from near normal to above
normal as the front arrives, falling back to near normal in its wake.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
At 2 AM Tuesday: On Friday morning an upper ridge will be along the
east coast, while an upper trough will be upstream over the MS River
Valley. The upper pattern amplifies, and the trough progresses to the
east coast by Saturday while a ridge upstream reaches the Great
Plains. By Monday the ridge reaches the Eastern Seaboard, while a
trough upstream amplifies over the Great Plains. By Tuesday the
ridge moves offshore, while the upper trough upstream broadens
across much of the CONUS.
At the surface, dry high pressure will cross our area from Friday
through Sunday. A cold front will approach from the west on Monday,
and the models suggest modest moisture with this boundary as it
crosses the area on Tuesday. Temperatures will cool from above
normal to near normal.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR conditions will continue through the
period as surface high pressure moves from the Appalachians to the
eastern seaboard. Light northerly surface winds this morning will
toggle southerly at all sites mainly from 15Z to 17Z. This flow
should keep most of the smoke away from the primary TAF sites, but
thin smoke layers are being observed near KAND. Thicker mid/high
clouds will likely increase from the west just beyond the current
TAF period as a front approaches from the west.
Outlook: Lower level Atlantic moisture could arrive from the south
on Wednesday, but restrictions may be sparse given the dry airmass
in place. A front will cross the region Wednesday night into
Thursday but with moisture along it drying up as it approaches. The
main threat of restrictions appears to be smoke plumes from
wildfires.
Confidence Table...
15-21Z 21-03Z 03-09Z 09-12Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.FIRE WEATHER...
Critical RH values will continue throughout the region today. Winds
will become light with high pressure moving over the area. Fuels
remain extremely dry and high fire danger will continue. A Fire
Danger Statement has been issued for all zones.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Fire Danger Statement until 7 PM EST this evening for GAZ010-
017-018-026-028-029.
NC...Fire Danger Statement until 7 PM EST this evening for NCZ033-
035>037-048>053-056>059-062>065-068>072-082-501>510.
SC...Fire Danger Statement until 7 PM EST this evening for
SCZ001>014-019.
&&
$$
SYNOPSIS...HG
NEAR TERM...NED
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...HG
FIRE WEATHER...
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
524 AM CST Tue Nov 22 2016
.SHORT TERM...(Today and tonight)
Issued at 328 AM CST Tue Nov 22 2016
Today and Tonight...the upper low across Northern NM lifts
northeast today and tonight. Plenty of moisture across Cntl Neb
with precipitable water over 0.75 inches in the RAP model and
ample theta- e in the 850-700mb layers feeding into an h700mb low
which should track east across Wcntl KS and then northeast through
eastern Neb. This is a little south and east of our most favored
track which is Nrn KS through Cntl Neb.
The ECM...RAP...GFS...NMM and ARW were close with the more eastern
track and were the basis for a blended forecast. The NAM and SREF
were western and northern solns for QPF. The NAM...GFS and RAP show
strong lift in the -10C to -20C snow growth zone which could support
a rain snow mix during the peak lift today. We are expecting 0.25
inches or more of qpf in 6 hours across srn Neb this morning and
ncntl Neb this afternoon. The model consensus shows h700mb
temperatures around -3C which is not particularly favorable but a
mix might develop at times of strong lift. The rain and snow is
forced by an area of frontogenesis and deformation indicated in the
RAP40 model. The system should lift northeast of Ncntl Neb tonight.
The temperature forecast is a bias corrected blend of the
GFS...ECM...NAM and SREF for highs in the upper 30s to upper 40s.
Warmest highs occur across Northwest Neb where little or no rain is
expected. Lows tonight are a blend of bias corrected guidance for
lows in the 20s to lower 30s. Teens are possible across the Western
Sandhills.
.LONG TERM...(Wednesday through Monday)
Issued at 328 AM CST Tue Nov 22 2016
Shortwave ridging will build across the region Wednesday ahead of
the next system slated to cross the area Thanksgiving day. The
farther south ECMWF has trended north, and is now in line with the
GFS and NAM which tracks the system across South Dakota. This will
be a quick moving open wave, and only scattered light rain and snow
showers are expected, with most of the activity to remain north of
our area. Pops have been almost completely removed from our forecast
area.
More significant ridging aloft translates west to east across the
central portion of the country Friday and Saturday. This will bring
a warm up once again to the region, with highs all areas expected
to be in the 50s on Saturday.
Sunday and beyond are a bit up in the air, as the models diverge
Sunday. As energy (troughing) moves into the western portion of the
country, the ECMWF is much faster bringing the trough into the
central portions of the country on Sunday. In fact, it spins up a
fairly significant cyclone. The GFS hold the energy back to the west
until Monday, and brings a weaker upper level trough through the
area. Downstream ridging across the Atlantic next week, will help
maintain a trough across the central or western portions of the
country, keeping the weather unsettled. At this time no big storm
appears to be on the horizon, but the pattern could support some
sort of storm development, and will be watched closely.
Temperature wise expect a return to cooler weather as the
troughing takes shape.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 524 AM CST Tue Nov 22 2016
MVFR/IFR CIGS are expected to develop along and east of a line
from KIML-KLBF-KONL today in rain/wet snow and low cigs. This
area of rain is currently taking shape on radar and there is a
chance it will form south or east of the aforementioned line.
Tonight...rain/wet snow will exit the KONL area but the SREF and
other models indicate MVFR cigs will move south through the
Dakotas into Ncntl Neb.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...Taylor
AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
629 AM EST Tue Nov 22 2016
.SHORT TERM...(Today and tonight)
Issued at 359 AM EST TUE NOV 22 2016
00Z raobs/latest wv imagery and RAP analysis show a confluent nw
flow aloft over the Great Lks btwn slow moving deep closed lo near
Maine and an upr rdg extending fm the Upr MS River Valley into nw
Ontario. Sfc hi pres rdg stretching fm NW Ontario thru Upr MI and
into IL in concert with very dry air shown on the 00Z YPL/GRB raobs
/00Z pwat as lo as 0.15 inch at YPL and 0.19 inch at GRB/ are
bringing dry wx to the cwa early this mrng even as sct lk clds
linger over the e half of the cwa in persistent chilly nnw llvl flow
to the e of the hi pres rdg axis. Some hi clds are spreading over the
upr rdg axis into the wrn cwa well in advance of vigorous shrtwv
lifting out of upr troffing acrs the wrn CONUS and into the scentral
Plains. The combination of the dry air/lgt winds have allowed temps
to fall aob 10F over the interior w half.
Main concerns in the short term are on pops/expected sn accums tngt
as shrtwv/sfc lo/attendant warm fnt aprch fm the sw.
Today...Although hi/mid clds wl continue to overspread the area fm
the wsw, expected slow exit of sfc hi pres rdg/accompanying llvl dry
air wl keep the cwa dry except for perhaps far wrn Lk Sup. Despite
the chilly start, expect hi temps to rebound to arnd 32.
Tngt...With larger scale waa/isentropic ascent dvlpg over the area
tngt, expect thickening clds and at least some lgt pcpn to spread
into portions of the cwa. There are some sharp model differences on
how far/fast to the ne this pcpn wl arrive. Given the sluggish
deep closed lo near Maine, models have trended a bit slower on moving
hi pres rdg now dominating the Upr Lks to the e. Given the more
tenacious hi pres rdg/accompanying llvl dry air, opted to hedge
toward the slower guidance on bringing accompanying pcpn to the e,
especially because the sharper isentropic ascent/deep lyr qvector
cnvgc/upr dvgc are progged to remain to the s of Upr MI. Tended
toward the lower qpf as well. Fcst h85 temps blo 0C, lingering llvl
dry air, and nocturnal cooling sug sn should be the predominant
ptype expect perhaps near the llvl warming influence of the Great
Lks. Considering all the negatives for sgnft pcpn, the fcst for tngt
wl feature no more than about an inch of sn over the far w.
.LONG TERM...(Wednesday through Monday)
Issued at 417 AM EST TUE NOV 22 2016
Shortwave trough over the middle conus will be main instigator of
the snow moving over western Upper Michigan on Wed morning. Sfc low
tied to the shortwave will be crossing northern half of IL by Wed
aftn which is slower and slightly farther south than what has been
shown in last couple days. Unless something changes significantly in
models, trend is not good for seeing advy level snow over much of
Upper Michigan. Only exception is in the far southwest cwa and even
here qpf and resultant snowfall has trended lower as well. Main
reason for downward trend is resilient high pressure ridge and dry
low level air. Ridge is in place due to confluent nw flow aloft btwn
upper ridge moving across the Great Lakes and strong upper low over
northeast conus.
Eventually on Wed soundings show dry air will be overcome as
shortwave trough crosses the western Great Lakes. Trough comes in
pieces though as shown by spread out deep layer q-vector convergence
from Ohio Valley north into Upper Great Lakes. Strongest area of mid
level q-vector convergence stays south of Upper Michigan while there
is a bit more h85-h7 q-vector convergence as weakening h85 low
tracks toward northern WI on Wed aftn. Isentropic ascent on 290-295k
sfcs is broad and weak which matches modeled weak omega/lift as
well. Overall seems that lack of focused ascent and minimal
enhancing upper level divergence will work against seeing widespread
moderate precip compared to how is looked a couple days ago. In
terms of how much snow could occur, soundings indicate dgz will be
very elevated in narrow layer above 12kft so SLRs will likely remain
blo 10:1 which will ultimately hold down snow amounts but also leads
to wetter/heavier snow.
So even though this snow will fall on very busy travel day before
Thanksgiving, do not have enough confidence that trends will not
continue to show lesser and lesser precip/snow over time. Latest
snowfall projections of mainly 1-2 inches Wed and again Wed night
struggle to come close to what is needed for advisory 2-4 inches/12
hr for wetter snow. Will keep an SPS going to highlight the light
but wetter snow for the busy travel day but will not be issuing
advisory. Better signal that heavier snow will fall to the southwest
across northern WI so adjacent NWS offices in DLH and GRB have issued
an advisory this morning for those areas. Dayshift can take another
look at it to see if trends reverse at all to see if advisory would
be needed in parts of our cwa.
Later Wed night into Thanksgiving deep moisture departs and could
see some drizzle, especially west and scntrl. OTherwise will be
patchy light rain or snow. Only light snow accumulations would be
over far east cwa in the morning and perhaps the higher terrain of
the Keweenaw with east wind off Lk Superior. h85 temps down around
-4c so there is limited over water instability. WBzero heights will
be borderline for rain/snow though especially near sfc as temps
rise into the mid 30s.
Another shortwave zips across western Great Lakes late Thu night
into Fri morning. Pops have increased and could see need for likely
pops eventually. High pop and low qpf setup with any snow amounts
staying under an inch.
Break in wx still in there for later Sat into Sun, then differences
develop in models in how quick and strong to bring out next low
pressure system for Sun and Mon. ECMWF faster while GFS is slower.
Blend of two along with GEM would suggest mix of rain/snow moving in
later Sun into Mon. Winds may be gusty depending on how deep the low
is as it lifts across the region. Still a bunch of time to sort out
those details. Overall pattern looks like it will remain active for
much of next week with chances for snow or mixed rain and snow.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 629 AM EST TUE NOV 22 2016
Dry air/lo invrn base associated with hi pres drifting slowly to the
e thru the Upr Great Lks today wl bring predominant VFR conditions
to the TAF sites. But there could be a period of MVFR cigs at SAW
this mrng and at CMX late this mrng into the early aftn when the
slowly shifting llvl winds at those sites associated the passing sfc
rdg axis present a favorable upslope wind component. Downslope
nature of the flow thru the day wl ensure no lo cigs impact IWD.
Although clds wl thicken tngt ahead of a lo pres aprchg fm the sw,
lingering llvl dry wl maintain VFR conditions at CMX and SAW. But
the arrival of some -sn late tngt at IWD wl result in lower MVFR
cigs after 06Z and perhaps an IFR vsby after 09Z.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 359 AM EST TUE NOV 22 2016
As a hi pres ridge extending s across western Lake Superior drifts
e, reaching eastern Lake Superior this aftn, lingering 20kt winds
over eastern Lake Superior will diminish this morning and fall below
15kt the rest of the day. Over the w half of the lake, light winds
under 15 kts will become se and increase up to 20kts under the
tightening pres gradient between the slowly departing hi and lo pres
moving newd from the central Plains. As the ridge shifts e and the
lo pres system over the Plains moves toward southern Lake Michigan
late on Wed, ese winds will increase up to 20-25kt across much of
the lake on Wed, with the strongest winds occurring over central and
eastern Lake Superior. Winds will then diminish to under 20kt for
Thu-Sat as the pres gradient across the area becomes relatively weak.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...KC
MARINE...KC
Area Forecast Discussion
National Weather Service San Francisco Bay Area
800 AM PST Tue Nov 22 2016
.SYNOPSIS...Clouds will be on the increase today with rain
chances starting tonight as a frontal system approaches the area
from the northwest. Additional storms will bring rain chances to
the area Friday and Sunday.
&&
.DISCUSSION...as of 8:00 AM PST Tuesday...Chilly start to the day
with many locations running 5 to 12 degrees cooler than 24 hours
ago. In fact, looks like 30s were common through the North Bay
with most other locations staying in the 40s.
Clouds will return to our entire CWA through the day as a system
moves in from the northwest. Based off of the latest HRRR and NAM
runs, rain should return to NW Sonoma County around 5 PM then down
to San Francisco just before midnight. Will do a few minor
modifications to the current forecast based off of latest
guidance.
.Previous DISCUSSION...A weak upper level ridge will bring dry
weather to the area today. Some low level moisture remains trapped
near the surface so patchy fog can be expected mainly in the North
and East Bay interior this morning. Clouds will increase this
afternoon from the northwest as a frontal system approaches. Rain
will begin in the North Bay early tonight spreading into the SFO
and MRY Bay Area during the overnight hours. Cold air cu can be
seen on satellite behind the system which will help push the front
through fairly quickly. So the front will be out of the area
Wednesday morning. There could be a period of moderate rain during
frontal passage especially in the North Bay and rainfall amounts
are expected to be 1/2 to 3/4 inches in the North Bay with locally
1 inch in the mountains...1/4 to 1/2 inch in the SFO Bay Area and
less than 1/4 inch in the MRY Bay Area. A few showers are possible
in the North Bay Wednesday afternoon as the upper trough moves
inland over northern California otherwise partly cloudy
conditions.
Cold air behind the system will allow temperatures to drop into
the mid to upper 30s in the interior valleys Wednesday night.
Thursday will be a dry day in between systems. Clouds will
increase Thursday night which should help moderate low
temperatures. Rain will begin in the North Bay early Friday but
there are indications the southward progress of the system will
be slowed as a wave forms off the central California coast. Rain
may not begin in the SFO Bay Area until Friday afternoon and the
MRY Bay Area Friday night.
A colder system with a more northerly trajectory is due to move
through the area Sunday. Will have to watch for possible frost
Sunday night if there is sufficient clearing. Both systems move
through quickly and are not expected to drop significant amounts
of rain.
Long range guidance indicates a return to ridging over the eastern
Pacific next week for dry conditions.
&&
.AVIATION...As of 3:28 AM PST Tuesday...For 12Z Tafs. Water vapor
and infrared imagery shows increasing upper level moisture
advecting in from the west/northwest, as a shortwave ridge exits
the region, and an upper level trough enters. Taking a look at
the fog product, isolated patchy areas of fog/low clouds can be
spotted underneath the higher level clouds, early this morning.
KSTS is currently reporting VIS under a mile. It is possible that
some terminals could see some fog/low level clouds before or
around sunrise, but VFR is expected to dominate. Will monitor
accordingly. A frontal boundary with showers, some heavy, moves
over the area late Tuesday, into early Wednesday. Gusty winds are
possible, mainly near frontal passage.
Vicinity of KSFO...VFR, but cannot rule out patchy fog or low
clouds before sunrise. Winds will stay relatively light to
moderate this afternoon, switching from SE this morning to W/SW in
the afternoon. Winds will pick up with the cold front, sometime
around 06-07z on Wednesday. Light to moderate rain is also likely
in this timeframe and could last through 12z Wed.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR, patchy fog possible before sunrise.
Light to moderate SE winds expected to turn more SW/W this
afternoon. Frontal passage expected around 09-10z Wednesday, with
gusty winds possible and rain showers likely.
&&
.MARINE...as of 03:25 AM PST Tuesday...Winds will increase out of
the south later this morning, ahead of a cold front. The cold
front is forecast to pass through the northern coastal waters
around 06z Wednesday, and through the southern coastal waters
around 12z. Showers, some heavy at times, can be expected later
this afternoon and this evening ahead of and along the
front, with lingering showers possible behind the front. More
unsettled weather will continue through the Thanksgiving holiday
weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...SCA...Pt Arena to Pt Reyes 0-10 nm from 9 AM
SCA...Pt Reyes to Pigeon Pt 0-10 nm from 9 AM
SCA...Pt Arena to Pigeon Pt 10-60 nm from 9 AM
SCA...SF Bay from 4 PM
&&
$$
PUBLIC FORECAST: Bell/W Pi
AVIATION: BAM
MARINE: BAM
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Area Forecast Discussion
National Weather Service Paducah KY
718 AM CST Tue Nov 22 2016
.UPDATE...
Issued at 718 AM CST Tue Nov 22 2016
Although originally planned during the routine morning forecast
package issuance, revised package to remove PoPs and Weather from
forecast prior to 00z Wednesday (6 pm). Uncollaborated changes
made by offices west of the WFO PAH forecast area within the last
couple of hours forced the update.
&&
.SHORT TERM...(Today through Thursday night)
Issued at 307 AM CST Tue Nov 22 2016
Finer resolution has been added to a majority of the pre-holiday
precipitation forecast (at least through daytime Wednesday) with
this package.
The deterministic and ensemble GFS, combined with the high
resolution ESRL HRRR and NAM-WRF (NMM version) strongly indicate
that measurable precipitation (reaching the ground-not virga) will
spread toward an Greenville-Poplar Bluff Missouri line by 9 pm CST
tonight, with lighter rain possible in Southwest Illinois, north
and west of Route 13 and Interstate 57.
At this time, the best chance for any thunderstorm activity will
likely remain confined to locations along and west of a
Greenville-Poplar Bluff Missouri line through 9 pm tonight. The
GFS and SREF continue to show some instability at or above 850 mb
during this time period, diminishing rapidly and shifting south of
the area before midnight.
In addition to the regionally blended model initialization,
utilized to the higher temporal resolution GFS guidance to capture
the slower eastward progress of measurable precipitation across
the WFO PAH forecast area tonight. Given the lack of low level
moisture advection, most of the initial precipitation loading will
be top-down, delaying the onset of measurable precipitation during
the daytime hours. With the nocturnal cooling of the boundary
layer, better moisture trajectory/advection of deeper layer
moisture into the area, a more modest coverage of rain will occur,
covering nearly all of the WFO PAH forecast before daybreak on
Wednesday.
The upper level trough and surface trough/cold front both maintain
their identity (i.e. orientation and intensity) per the GFS from
3 am through Noon on Wednesday, with subtle vorticity lobes
moving around the base of the mid-upper level trough. This should
maintain a slow, but a persistent zone of lift moving through the
area late tonight through early Wednesday afternoon. Kept a
categorical mention of PoPs/Weather in place during this time,
slowly shifting the highest PoPs eastward with time.
Made an error with last night`s forecast for lows this morning,
underestimating the cirrus shield in place. Re-adjusted low
temperature forecast to reflect upward transition of temperatures
overnight and through daybreak this morning.
For Thanksgiving day, dry conditions should still be the rule, but
clouds will be slow to clear from the southwest, slowing andsignificant
warming during the day east of the Mississippi River.
Relative humidity values will likely dip into the 25-30 percent
range south of Madisonville KY-Goreville IL-Greenville MO line by
midday...which may still lead to some elevated fire danger. Please
refer to the Fire Weather discussion for more details this week.
.LONG TERM...(Friday through Monday)
Issued at 307 AM CST Tue Nov 22 2016
Black Friday will still see a swift but dry cold front`s passage, as
a low pressure trof axis aloft spills its energy across the mid
Mississippi/lower Ohio river valley. Main surface reflected impact
will be a reinforcing shot of cool air for Friday night, plunging
Lows back into the 20s.
After this front`s passage, High pressure slides across the region
nicely for Saturday, returning temps to near normal with mid 50s/mid
30s slated for the first half of the Holiday weekend and plenty of
sunshine to boot.
With the surface high anchoring across the southeast U.S. to finish
out the weekend, and upper heights ridging across the Mississippi
river valley, we`ll see return flow southerlies and a warming
thermal profile as temps nudge toward the upper end of the 50s for
Highs and meander in the 40s for lows.
Strong height falls from our next developing weather system will be
commencing in the Lee of the Mtns, and a powerful 130 KT jet will
stream some of this associated moisture overtop the ridge and spill
across our Region as early as Saturday night-Sunday, but esp Sunday
night. Pops make a broad expansion over the broken down ridge Sunday
night into Monday, with the blend yielding likely cat pops despite
significant model timing differences continuing. It`ll probably end
up being a categorical event once these internal model member issues
are resolved with time, but for now, it appears the collaborative
stomach is for a broad likely category QPF event focused on late
Sunday night-early Monday. Suspect we`ll be including some thunder
in this forecast as soon as the collaborative stomach is there for
its inclusion north of the Mason Dixon (already residing south).
Also the system holds potential to increase QPF from the blend on
the order of .5 to 1 standard deviation, but again, being a late
day 6 to day 7 event, we won`t propose deviating off the mean like
that til some model differences can resolve with time. Having to
adjust/blend some QPF with timing of best chance Pops/this
package, which should also resolve a little better with time.
&&
.AVIATION...
Issued at 543 am CST Tue Nov 22 2016
Gradually decending VFR ceilings will dominate the WFO PAH TAF
locations for the 12z Tuesday forecast package as moisture slowly
saturates the atmospheric layers from aloft. Ceilings are expected
to remain at or above 8kft agl through at least 00z Wednesday.
Some scattered decks around 1500 ft are possible after 03z
Wednesday, but primary ceilings will still be VFR. There should be
no visibility restrictions below VFR through 12z Wednesday, but
rain will be the primary obscuration during the last 6 hours of
the forecast period.
&&
.FIRE WEATHER...
Issued at 307 AM CST Tue Nov 22 2016
Elevated fire danger is likely again this afternoon, with continued
dry fuels, relative humidity dropping through the 30s percentile,
and stiffening winds with gusts through the teens mph. Incoming rain
chances later tonight and Wednesday should bring relief in terms of
higher relative humidity and at least a light wetting rain
increasing moisture content of fuels.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...Smith
SHORT TERM...Smith
LONG TERM...DH
AVIATION...Smith
FIRE WEATHER...DH
Area Forecast Discussion
National Weather Service Aberdeen SD
341 PM CST Tue Nov 22 2016
.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 340 PM CST Tue Nov 22 2016
Much of the precipitation across the northeast CWA has dissipated
and have therefore canceled the Winter Weather Advisory. Temps have
largely remained above freezing today as well, which has greatly
limited any impacts of icing. The only exception is along the Coteau
ridge where temps are hovering around 31 or 32 degrees. Areas of fog
and drizzle now remain over the eastern CWA, based on web cams and
observations. Although, feel the biggest impacts from any drizzle or
freezing drizzle remain in and around the Coteau region. Inserted
this into the grids for the remainder of the afternoon and evening
hours. Main area of precip associated with the surface low continues
to drift northward across southeast SD, but feel it will be rather
difficult for it to penetrate much into the CWA, if at all this
evening. This is shown by the HRRR and other hi-res models. Have
therefore reduced POPs quite a bit this evening as well as QPF/snow
accums. Will have to monitor fog overnight, especially over the east
within the trough axis where winds will be lightest and moisture
pooling with be the greatest. Tried to time the departure of fog
with the onset of slightly stronger winds on the back side of the
surface trough.
Will also be watching the massive stratus deck sliding south across
ND. Models suggest this will overspread the western CWA later this
evening and have increased sky cover grids accordingly. Looks like a
cloudy night is in store, with clouds continuing into tomorrow, more
than likely. Weak surface ridge over the area tomorrow, with weak
mixing at 925/850 mb as well, so it may be hard to scour things out.
Have also increased sky cover through Wednesday, but will not be
surprised if later shifts have to hold on to cloud cover even
longer. Given the abundance of clouds tonight, have increased lows a
couple degrees, but they still may be a bit too cool for some areas
and later adjustments may be needed.
.LONG TERM...(Wednesday Evening through Tuesday)
Issued at 340 PM CST Tue Nov 22 2016
Thursday we will see a shortwave enter the plains, with a weak
surface low expected to cross South Dakota. Isentropic forcing will
result in some modest vertical lift, upwards of around 10 microbars,
co-located close the vicinity of what is more or less a stacked
low. SREF probabilities for measuring moisture are around 70-90
percent along an axis from Lemmon ND - Mobridge - Redfield -
Watertown. SREF probabilities for measuring 1 inch of snow are also
around 40 percent at the highest, around the Watertown area.
Profiles mainly support snow, though the NAM Mobridge profile hints
that ice introduction may be an issue. Will stick with the mainly
snow forecast at this point.
Friday-Saturday the region will be under a ridge aloft. 850/925mb
temperatures will warm during this time, peaking around a standard
derivation above climo.
Models diverge over the handling of a system moving into the region
late in the weekend, and while differing on timing - both the GFS
and ECMWF bring a well developed system into the northern/central
plains, and future forecasts will need to be monitored for potential
winter storm impacts.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1144 AM CST Tue Nov 22 2016
MVFR/IFR CIGs will continue at KABR and KATY through the day and
likely through the overnight hours. KATY has the potential to see
CIGs below 500ft. VSBY in KATY will also be around 1SM to 3SM
this afternoon with BR/FG potential lasting into the evening as
well. KATY may also see some mixed precipitation this afternoon
and evening in the form of -DZ or -RASN. Across KMBG and KPIR,
currently seeing VFR conditions. Although, MVFR CIGs are expected
to arrive later this evening.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
SHORT TERM...TMT
LONG TERM...Connelly
AVIATION...TMT
Area Forecast Discussion
National Weather Service Grand Forks ND
316 PM CST Tue Nov 22 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 256 PM CST Tue Nov 22 2016
Current radar and surface observations indicate that all freezing
or frozen precipitation has move east of the Red River into
Minnesota...where it is difficult to find any reports of
precipitation other than snow. Fosston does continue to show UP. Main
urban areas to be impacted by afternoon accumulation will be
Crookston to Bemidji...Thief River Falls...Warroad and Baudette
and all other higher traffic areas across northwestern Minnesota.
The band of snowfall continues to peter out as it advects east of
a Roseau to Crookston line and advisory level impacts are
diminishing. For this reason, have shortened the end time of the
advisory to 7 PM CST. Main impact now will be the light snow
moving over areas that may have received some patchy freezing rain
this morning where temps had fallen as low as 28 F. Less
confidence for advisory level impacts across Otter Tail county but
as we get into higher elevations around Wadena UP is being
reported.
The HRRR has a decent handle on current trends and continues to
decay the band of precip through 23Z. The latest band however does
reinstensify this are in the 01Z to 03Z timeframe however low
confidence we will see redevelopment. Models also vary on
northward extend of precip band across SW Minnesota, however the
HRRR keeps it well to the south of the CWA and will trend POPs in
the southern valley down after midnight. Snow expected to continue
in the far east until early Wednesday morning.
With no strong push of dry air, expect low level moisture to
continue through the day tomorrow and possibly bring some fog or,
with drying aloft, patchy drizzle late tonight in the west and
across the region tomorrow. At the current time not enough
confidence on exactly where this will occur and elect to not add
drizzle to the wx grids but certainly something to look at after
this system winds down. Very little diurnal temperature change
over the next 24 hours and overnight lows should remain just below
freezing with daytime highs tomorrow struggling to rebound with
little solar, possibly reaching the mid 30s by mid afternoon.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 256 PM CST Tue Nov 22 2016
Wednesday night to next Tuesday...Overall seasonal temperature
regime with two time periods with precipitation possible. First snow
departs NW MN Wednesday night with the 500mb fast flow bringing the
next weather system and chance of PoPs across the southern valley
during the daytime on Thanksgiving. Expecting some -sn with maybe a
rasn mix in the afternoon as daytime heating brings temps into the
mid 30s. System departs quickly Thursday night and 500mb ridging
with SFC high pressure spread across the northern plains. This
pattern sets up for the long holiday weekend with highs in the mid
to upper 30s and lows in the 20s.
By Sunday night into Monday the 500mb ridging breaks down with a
along wave trough inducing a strong colorado low pressure system to
develop and move out over the central plains. Placement and track of
that system and the evolution of the upper long wave pattern remain
in flux. Ensemble spreads indicate significant precipitation is
likely somewhere across the northern and central plains with the
potential for a long duration event as the upper low stalls and
pinwheels over the north central CONUS for the mid week time frame.
As this system wraps up to our south and lifts northward PoPs
increase from our southeast to northwest for Monday and Tuesday.
Once again with this system there is minimal cold air to work with
as there remains well above normal conditions across Canada,
where here remains little to no snow pack.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 108 PM CST Tue Nov 22 2016
Cigs in areas of precipitation are predominantly MVFR and cigs
further west are IFR as saturated low layers of the atmosphere
hold stratus deck in place (may even fly through some drizzle
around DVL). Expect cigs to fall behind the wintry mix of
precipitation and remain low MVFR to IFR for remainder of the
period.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...Winter Weather Advisory until 7 PM CST this evening for
MNZ001>003-005-006-008-009-013>017-022>024-027-028-030>032-
040.
&&
$$
SHORT TERM...Speicher
LONG TERM...JK
AVIATION...Speicher
Area Forecast Discussion
National Weather Service Sioux Falls SD
343 PM CST Tue Nov 22 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 341 PM CST Tue Nov 22 2016
Intense upper level wave moving northeast into far southern Nebraska
this afternoon. Deformation zone to the north has been
concentrating band of light rainfall, with nose of PV advection into
mid Missouri valley finding additional development of showers and
even isolated rumbles at mid afternoon. Temperatures dancing on the
warm side of 32 degrees this afternoon in and around southwest MN,
with just a few spots trying to hold at 32 degrees. Calls around the
area have not revealed any issues with icing, nor has any
groundtruth been found to automated reports of snow at Tracy and
Slayton. Temps aloft remain warm, with a fairly deep layer of 4000-
6000ft suggested to reside in the 0 to +2C range before a small sub-
freezing layer closer to the surface. Challenge for the night will
be dealing mainly with precipitation and potential transition to
snow.
Strong wave lifting northeast is beginning to shear, and expect that
pulse of precipitation will fill into the location of deformation
zone by late afternoon and early evening. HRRR has been handling the
overall trends quite well, and have followed general distribution of
pops along those lines. With rain prevailing through the late
afternoon and even early evening, will take gradual cooling with
dynamic lift and advection of cooler air into inverted trough zone
to begin to push deep enough cooling to start a change to snow.
Total snowfall will be limited by two things, the tendency for the
banding to weaken starting around 03z-06z window, and the time it
takes for cooling to occur. Combination will be likely to bring the
greatest snowfall potential for southwest Minnesota, where up to a
couple inches will be possible. Have continued the winter weather
advisory for this, and potential that even a bit of spotty light
freezing precipitation will occur very late afternoon or early
evening before the change. Inverted trough will continue to push
eastward, and areas ahead of feature will also be susceptible to
some areas of fog, and perhaps even drizzle with depth of saturation
fails to reach ice formation, especially in east central SD.
Some light snowfall may linger early, but will also have shearing
trough causing loss of deep enough saturation to support ice. If not
for the overall trend to subsidence forcing, would think there could
even be a bit of patchy drizzle or freezing drizzle across parts of
southwest MN and northwest IA through the morning.
Temps tonight will be slow to change, and likely not to get below
the lower 30s. Not looking very favorable to get much in the way of
sunshine with trajectory unlikely to allow much drying at lower
levels with weak ridging pushing into the west by late afternoon. As
a result, temperatures will be sluggish to change for most part,
mainly 30s with a few readings into the lower 40s where less/no
snowcover.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 341 PM CST Tue Nov 22 2016
Main focus in the mid range will be on the next open wave system,
which arrives in the central High Plains on Thanksgiving morning and
quickly slides east through the region. While this system looks to
have decent dynamics, with a strong jet moving across the plains,
moisture will be lacking, especially early on in the event. Expect
precipitation to begin moving into north central SD Thursday morning
then expand across the forecast area midday into the afternoon. The
better lift and highest chance for precipitation will be along and
north of I90 and into the Iowa Great Lakes region. Temperature
profiles have warmed a little with the 12z runs, resulting in warmer
temperatures aloft and surface temperatures rising into the mid 30s
to lower 40s as the precipitation threat increases across the area.
Profiles also suggest a lack of ice crystals in the clouds for much
of the day, only changing over to snow as the system is winding down
Thursday evening. As a result, snowfall amounts look very minimal -
less than 1 inch - and mainly centered along and north of highway 14.
Drier pattern settles into the central states Friday into the
weekend with upper level ridging and a warming pattern returning.
Skies will clear while return flow brings light southerly winds on
Friday. Winds pick up a little on Saturday, but will improve
temperatures into the lower 40s and lower 50s.
The next upper level wave approaches on Sunday afternoon and Sunday
night, but there remains some uncertainty in the track and timing of
this system. Both the GFS and ECMWF really strengthen the system,
however the ECMWF has a slower and more westerly track compared to
the GFS. Both models show the potential for this low to linger over
the northern Plains and upper Midwest for several days at the start
of next week. Thermal profiles suggest that the precipitation type
also looks like a mix of rain and snow, but again would depend on
the final track of the low.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1131 AM CST Tue Nov 22 2016
IFR to low IFR conditions are expected to prevail through the
period as low pressure system moves through the area. Upper wave
will mainly produce precipitation along and east of a line from
Bon Homme to Marshall MN. Expect precipitation to remain as rain
through the afternoon, but will transition over to snow this
evening from the northwest to the southeast. Visibility could drop
to around 1 mile at times in snow. Snow should shift east after
06z, but ceilings should remain in the IFR to LIFR range through
18Z tomorrow. As the wave moves through the region, light easterly
flow will transition to northwest, but remain fairly light.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...Winter Weather Advisory until midnight CST tonight for MNZ071-
072-080-081-097.
IA...None.
NE...None.
&&
$$
SHORT TERM...Chapman
LONG TERM...
AVIATION...BT
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
406 PM CST Tue Nov 22 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 405 PM CST Tue Nov 22 2016
Late this afternoon, the surface low was analyzed across central
Kansas with an inverted surface trough extending north-northeast
into southern Minnesota and we`ve seen a steady stream of light
precipitation today lifting north through the area. It`s quite a
complicated forecast as precipitation type remains a big issue, and
hence confidence in amounts remains very low for being so close in
time to the event. Didn`t make a lot of changes to the going
forecast except to tighten up the PoP gradient across far western MN.
Current thinking for the metro area is the 2-4" range with the
higher end on the north side and the lower end to the south. Then
rain/snow line this evening should be just south of the metro area.
Highest snow totals for closer to 3-5" are expected up the I-35
corridor north of the Twin Cities. In terms of snowfall rates and
timing, the heaviest snow looks to fall this evening from 8PM-
Midnight.
Model soundings from the HRRR, RAP, NAM, GFS all seem to differ on
low level thermal profiles hovering around the critical freezing
mark and just how cool the surface will be. A deep layer from 700mb
down to the surface looks to hover near that freezing mark so very
slight fluctuations will cause big difference in P-type and hence
impacts. We are leaning to the slightly cooler side based on latest
observations and some of the hi-res guidance like the HRRR has
trended to more snow accumulation than it was indicating earlier
today. So, we still think a couple inches of snow is likely in east
central MN through west central WI by midday tomorrow.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 405 PM CST Tue Nov 22 2016
Confidence increasing in some light snow rain/snow Thursday evening
across central and southern Minnesota into west central Wisconsin. A
much larger, more powerful storm will bring widespread rain along
and east of the low track, with heavy snow northwest of the low
track. It is possible that western MN could see the heavy snow with
this system if the low tracks through central Minnesota. Meanwhile
eastern MN and western WI should see rain.
Early afternoon water vapor imagery with GFS 500mb heights showed an
upper level wave approaching the Pacific Northwest, with another one
upstream over the Allucian Islands. On Thursday this first wave will
move west to east across the CONUS. Isentropic ascent ahead of this
wave will lead to saturation, and forecast soundings show some light
precipitation during the late afternoon and evening hours. Thermal
profiles support snow for most locations, with a rain/snow mix on
the southern side near I-90. Snowfall totals of around 1 to 2 inches
seem reasonable, which wont be enough for winter headlines, but
should be enough to make the roads slick for the Thursday evening
travelers.
The weekend looks dry and relatively mild with highs in the mid 40s
to the south and mid 30s for the areas with snow. Late Sunday the
aforementioned second upper level wave will emerge from the 4-
corners region and lift northeast toward the Great Lakes. As of now,
most of the forecast area is in the warm sector of this storm which
means the majority of the precip will fall as rain. The one
exception is western Minnesota where the band of heavy snow could
set up. The super-positioning of the subtropical and polar jet means
this storm has the potential to over achieve, so it should be taken
seriously. However, the variability in the track indicates that it
is too early to determine where the heaviest precipitation will fall
and what type it will be.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1204 PM CST Tue Nov 22 2016
Precipitation continues filling in from the southwest and there
was little break between the first and second round. Within the
last hour, the precip moving across southern Minnesota has become
snow across many locations north of Mankato as the atmosphere is
just cool enough to allow snow to the ground. Generally expect a
mix of rain and snow to continue this afternoon depending on your
location. North of the Twin Cities will likely see primarily snow
for the remainder of the day, and south will have more rain for
through the afternoon. There is still differences in the guidance
on precipitation type for the next several hours so leaning on the
guidance that seems to be verifying best is the way to go. Across
the metro, a changeover to snow occurred a little earlier than
expected but that could still go back and forth during the
afternoon. Expect IFR conditions tonight through tomorrow morning
and possibly low MVFR during the day tomorrow.
KMSP...A quick changeover to snow occurred but it is plausible
that the p-type goes back and forth for a few hours this
afternoon. There is rain near Mankato and south currently and that
activity is lifting north. The rain/snow line will be very close
to MSP this afternoon.
/OUTLOOK FOR KMSP/
THU...MVFR cigs lingering. Chc -SN Thu night. VRB wind 5 kts.
FRI...VFR. Wind NW 5 kts.
SAT...VFR. Wind SSE 5 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 3 PM CST Wednesday for WIZ014>016-
023>028.
MN...Winter Weather Advisory until 6 AM CST Wednesday for MNZ042>045-
049>053-057>063-066>070-076>078.
Winter Weather Advisory until midnight CST tonight for MNZ041-
047-048-054>056-064-065-073>075-082>085.
&&
$$
SHORT TERM...SPD
LONG TERM...JRB
AVIATION...SPD
Area Forecast Discussion
National Weather Service Tulsa OK
245 PM CST Tue Nov 22 2016
.DISCUSSION...
The main forecast challenge will focus on severe potential
tonight and again on Sunday night in association with two strong
mid/upper storm systems.
An active and progressive upper air pattern is in place over the
CONUS this week and should continue into the holiday weekend,
before becoming more amplified and less progressive next week.
The first in what will be a series of shortwave troughs is
ejecting into the Plains today. At the surface, low pressure was
centered over West Central KS with a dryline trailing south across
Central OK. A cold front was dropping south and east on its west
side and will eventually overtake the dryline by this evening as
the surface low lifts off to the northeast. The warm sector over
our area continues to slowly moisten but instability remains very
limited by widespread cloud cover. A gradual destabilization of
the warm sector will continue into the evening, with progged
MUCAPEs around 500 J/KG reaching into SE OK. The latest short term
model data suggests a spatially and temporally limited severe
threat for the evening. To the west of the warm conveyor showers
and storms and east of the merging cold front/dryline, the latest
runs of the HRRR have been developing discrete cells over South
Central OK between 00z-02z and then tracking them into Southeast
OK, and show some updraft rotation. Kinematic fields will be more
than supportive of rotating storms, with instability being the
main limiting factor. Thus, a non-zero damaging wind/tornado
threat exists with any discrete cells that can form ahead of the
cold front/dryline this evening. Since the instability axis will
become more narrow with time and northward extent, storm potential
should drop off after midnight as the activity moves into AR.
Another wave will pass by to our north on Thanksgiving, and will
push another front down into the region by late in the day. This
should be a dry front, due to the fact that today`s front will
have displaced the good low level moisture pretty far down to our
south and east. Thus, the weather will be very cooperative for
this very busy holiday travel period this year.
The next upper storm system to affect the Plains will arrive late
in the weekend. This system will likely be the most potent, with
contributions from a strong subtropical upper jet and eventually a
potent Polar jet punching into the Western CONUS from the Pacific.
This system should have a better low level moisture to tap into
than this system, mainly due to the fact that the previous systems
will not scour out the Gulf. Thus severe potential will likely be
increasing going into Sunday evening ahead of the cold
front/dryline and should be greater than tonight`s threat given
better moisture.
Temperatures overall should be above normal thru the bulk of this
forecast. Going into next week this could change however as deep
cyclonic flow develops over the Central CONUS.
Lacy
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 48 59 36 66 / 40 0 0 0
FSM 52 60 38 66 / 80 10 0 0
MLC 50 59 37 68 / 50 0 0 0
BVO 47 58 30 65 / 30 0 0 0
FYV 51 55 32 61 / 70 10 0 0
BYV 52 57 36 60 / 70 10 0 0
MKO 49 58 36 64 / 50 0 0 0
MIO 49 55 33 62 / 50 10 0 0
F10 47 59 37 66 / 40 0 0 0
HHW 50 62 40 68 / 80 0 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
LONG TERM....30