Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/05/18
Area Forecast Discussion
National Weather Service Duluth MN
527 PM CST Sun Feb 4 2018
.SHORT TERM...(This evening through Monday)
Issued at 310 PM CST Sun Feb 4 2018
Dangerous wind chills are expected once again tonight, even
though temperatures won`t be as cold. Otherwise, continued quiet
through the short term.
A broad area of high pressure was in control across the region
this afternoon with mainly sunny skies for most locales. Meanwhile
a weak shortwave trough was digging into northwest Ontario. Weak
forcing for ascent in the mid-levels has produced an area of
cirrus which has moved into northern Minnesota during the past few
hours. The cirrus is rather thin and surface features are
discernible through the clouds in the GOES-16 visible imagery. RAP
and NAM guidance highlights this area of clouds with enhanced
700-500 mb layer RH. Limited moisture upstream along with a
stretching of the moisture plume would suggest the clouds will
continue to thin through much of the night as they sag southward.
Have decreased cloud cover overnight for most locales at least
until 09Z. As the shortwave trough approaches the Northland on
Monday, mid-level height falls should be sufficient to increase
cloud cover over the central and southern portions of the forecast
area. While we`ve been under weak warm air advection for much of
the day, the shortwave trough is accompanied by another, however
weaker, surge of Arctic air aloft. With less cloud cover, plenty
of cold air, and fresh snow pack, have lowered min temps tonight
below the bias-corrected blend. Look for low temperatures in the
teens below zero for most locales in Minnesota and away from the
lake in northwest Wisconsin. With the thin cirrus overhead, was
not as aggressive in lowering temps as yesterday at this time.
Could still see some local cold spots dipping into the -25 to -30
range tonight. With the revised temperatures, wind chills will be
a concern tonight. Most areas should see wind chills in the -20
to -25 range early this evening, trending colder overnight.
Winds will become light for a time overnight, but will pick up
Monday morning with the coldest wind chills expected between 10Z
and 14Z. Conditions improve across the southern tier of zones by
10 AM with the remainder of the Northland noting wind chills in
the teens below zero by noon.
The shortwave trough along with a weak surface response will
progress through the Northland on Monday with partly cloudy skies
anticipated. Highs for Monday appear on track so only made a few
minor tweaks warmer in the St. Croix Valley and a degree or two
colder in far northern Minnesota.
.LONG TERM...(Monday night through Sunday)
Issued at 310 PM CST Sun Feb 4 2018
Much below normal temperatures will continue to dominate the
weather for much of the long term period. High pressure will move
across the Upper Midwest on Monday night, reaching northern
Iowa/southern Minnesota by 12Z Tuesday. Temperatures Monday night
should be well into the teens and possibly even 20s below zero
once again. The surface high will then move eastward through the
Great Lakes on Tuesday, as a weak area of low pressure moves from
the Northern Plains into the western Great Lakes. This system
could bring some light snow to portions of the region,
particularly the south/south central areas. The clouds associated
with this system should help to limit the temperature drop a bit
on Tuesday night, with lows ranging from the single digits below
zero in the south to the teens below zero north. Daytime highs on
Wednesday will temper somewhat, reaching the single digits and
teens above zero. Temperatures will then drop back into the deep
freeze for the Wednesday night through Friday night time frame,
with lows once again ranging from the single digits and teens to
20 below zero. Yesterday, it looked like we may see some
accumulating snow from a system sliding eastward across the
region. The latest models take this precipitation well to the
south of the Northland, leaving us with dry and very cold weather.
The model forecasts for next weekend are all over the place. GFS
Ensemble members show a great deal of variability. As a result,
confidence in any particular solution is fairly low. The 8 to 14
Day Outlook from CPC does indicate the potential for above normal
temperatures during that time, so there may be a bit of a reprieve
from the cold after the upcoming week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 526 PM CST Sun Feb 4 2018
VFR through the forecast. Gusty surface winds will be subsiding by
03Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH -11 9 -13 8 / 0 0 0 0
INL -17 5 -19 5 / 0 0 0 0
BRD -11 11 -14 9 / 0 0 0 0
HYR -12 14 -13 9 / 0 0 0 0
ASX -7 13 -8 10 / 0 10 10 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Wind Chill Advisory until 10 AM CST Monday for WIZ001>004-
006>009.
MN...Wind Chill Advisory until noon CST Monday for MNZ010>012-018>021-
026.
Wind Chill Advisory until 10 AM CST Monday for MNZ025-033>038.
LS...None.
&&
$$
SHORT TERM...Huyck
LONG TERM...DAP
AVIATION...GSF
Area Forecast Discussion
National Weather Service Honolulu HI
411 PM HST Sun Feb 4 2018
.SYNOPSIS...
A front will interact with a moist and unstable airmass to bring
active weather to parts of the state through midweek. Heavy
rainfall will bring the threat of flash flooding. There will be a
risk of thunderstorms with gusty winds, and possibly more winter
weather to the Big Island summits by the middle of the week.
&&
.DISCUSSION...
Bands of showers and embedded thunderstorms have continued to
impact Kauai this afternoon as a cold front, a moist and unstable
airmass, and upper level support combine to produce conditions
favorable for deep convection. Shear through the layer remains
marginal to produce severe convection, however enough to produce
organized storms, some of which are producing wind gusts and
possible waterspouts as they have been moving across the Kauai
coastal waters on Kauai 88-D. For the rest of the afternoon and
early evening the conditions producing these showers and
thunderstorms will shift across the Kauai Channel and approach
Oahu. Global and hi res models including HRRR show these showers
beginning to impact Oahu around sunset.
The forecast for the short term continues to indicate the best
chance of heavy rain and thundershowers moving from Oahu this
evening to Molokai, Lanai and Maui Islands around midnight. A flash
flood watch remains in effect for all of those areas.
For Kauai, the focus for additional showers will be the north
facing side over night due to orographic lift as the cold front
moves in. With already saturated soils any additional rainfall
tonight could still result in flash flooding, and the flash flood
watch remains posted there.
For the Big Island, the initial front is expected to weaken and
stall as it reaches the west side late Monday, thus the threat of
heavy rainfall appears much lower there at this time.
Details of the forecast remain somewhat unclear beyond late Monday
as the models vary in timing and amplitude of additional
shortwaves rounding the mid latitude trough. Unsettled winter-like
weather remains a good bet through at least mid week, with
instability remaining over the state and the possibility of areas
of deep convection developing anywhere across the state, with the
potential for snow on the high summits of the Big Island Tuesday
or Wednesday.
&&
.AVIATION...
A front in the vicinity of Kauai this afternoon is continuing to
bring lines of clouds, showers, and thunderstorms to the islands
this afternoon. The front is expected to slowly push to the east,
spreading this unstable airmass to the central islands overnight,
and to the Big Island tomorrow.
AIRMET SIERRA continues for IFR conditions from the Kauai
Northwest Waters to Oahu and adjacent coastal waters. Eventually
anticipate these conditions to move over Maui County, but the
forward progress has slowed since earlier this morning.
SIGMET WHISKEY remains in place for thunderstorms along and ahead
of the front. The southern portion of the SIGMET includes Kauai
and waters west of Oahu. As the thunderstorms move to the east,
anticipate the SIGMET to shift eastward as well.
Icing remains a possibility in the upper levels from Kauai to
Oahu, even outside thunderstorms, so mention of the possibility
remains in AIRMET ZULU.
&&
.MARINE...
The current northwest swell continues to diminish, but surf heights
remain just above advisory levels along north and west facing
shores of the smaller islands, so the High Surf Advisory (HSA) has
been extended through tonight. Surf heights have dropped along
west facing shores of the Big Island, as well so those areas have
been downgraded to an HSA through tonight. Surf heights are
expected to fall below advisory level for all islands on Monday.
The large west-northwest swell has dropped enough that seas have
fallen below the 10 foot advisory threshold, so the Small Craft
Advisory has been cancelled for all coastal waters. The next
potential for small craft conditions will be during the second
half of the new week.
A front, currently near Kauai will continue the chance for
thunderstorms for surrounding areas tonight and spreading to the
Big Island by Monday night. Thunderstorms that develop may
contain gusty winds and heavy rain.The front is expected to stall
and weaken over the central waters during the coming week,
continuing the slight chance for thunderstorms through Wednesday.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Monday afternoon for Niihau-Kauai-Oahu.
High Surf Advisory until 6 AM HST Monday for Niihau-Kauai
Windward-Kauai Leeward-Waianae Coast-Oahu North Shore-Oahu
Koolau-Molokai-Maui Windward West-Maui Central Valley-Windward
Haleakala-Kona-Kohala.
Flash Flood Watch through Monday afternoon for Molokai-Lanai-
Kahoolawe-Maui.
&&
$$
Discussion...Brenchley
Aviation...MBallard
Marine...TS
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
901 PM EST Sun Feb 4 2018
.UPDATE...
Issued at 901 PM EST SUN FEB 4 2018
So far forecast actually seems to be in pretty good shape, with a
cold front preparing to move through, giving us a quick burst of
snow. Lingering llvl moisture has led to drizzle and light rain
currently across the rest of eastern KY. Based on latest
temperatures, and trends upstream, do not expect any freezing
drizzle concerns as was the case in areas to our north in Ohio.
Rather it looks like it will onset as rain, and then with temps
quickly falling 6 degrees or more in an hour, transition to rain.
Temps aloft will be cooler, so could see snow falling even with
temps just above freezing still at onset. A pretty good band of
snow is currently going through southern IN and northern KY,
however after talking to LMK, total snowfall amounts within the
heaviest portion of the band were only a dusting in Madison, IN.
Do not see any need to upgrade products with that in mind,
especially given how quickly this band and system as a whole are
moving. In fact, POPS and WX are actually still in very good
agreement with the latest trends. Added in some drizzle for a
couple of hours across much of the CWA before main precip starts
moving in, and also made some minor tweaks to temps and winds,
but overall will hold on to ongoing forecast and continue to
update throughout the evening as needed once the bands of
rain/snow start impacting us. All updates have been sent to
NDFD/web. A new ZFP was also sent out to remove pre-first period
wording and include addition of evening drizzle.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 350 PM EST SUN FEB 4 2018
20z sfc analysis shows a meso-low exiting the area to the east
while the main system low is progressing through the eastern Great
Lakes. The departing meso-low is taking the last of the rain
along with it and allowing the area to warm into the upper 30s and
lower 40s. Meanwhile, to the northwest, a sharp cold front is
approaching associated with the parent low. Winds ahead of the
front are becoming southwester to westerly across eastern
Kentucky and picking up in speed to between 10 and 15 mph over the
western parts of the area. Dewpoints are not far from
temperatures in the mid to upper 30s which, under overcast skies,
are supporting some areas of fog, mainly on the ridges. With the
warming temperatures and rain earlier the slush appears to be off
of area roads, unfortunately they will likely still be wet when
the sub freezing air moves in later tonight.
The models are in good agreement aloft through the short term
portion of the forecast. They all spiral a strong wave of energy
into the eastern Ohio Valley late this evening helping the trough
to bottom out over the region. Lower heights and a tail of mid
level energy will pass through eastern Kentucky quickly, though,
with a rebound after 12z Monday. Heights will then flatten out
into Monday evening with the flow becoming southwest. Additional
energy then streams into the southern part of the Ohio Valley
crossing northern Kentucky into Tuesday morning. Given the model
agreement have favored a blended solution with a lean on the
higher resolution HRRR and NAM12 for wx specific details.
Sensible weather will feature a brief lull in activity from late
afternoon into the first part of the evening in the dry slot of
the larger weather system. This will end abruptly, though, after
00z Monday as a strong cold front pushes into the area with
another round of rain changing to snow and much colder air. Gusty
northwest winds will accompany this boundary and the snow showers
will likely come down moderate to heavy for a time - both factors
contributing to low visibility and potentially squall-like
conditions. Looking at generally a half an inch of accumulation
for most places with up to an inch possible from any heavier snow
showers in the late evening. The higher terrain in the far east
could pick up a touch more snow later tonight before the system
clears out in the pre-dawn hours. Finally, temperatures will
bottom out in the mid to upper teens most places by dawn easily
freezing any wet spots left from the day`s rains or fresh snow
with the cold front. Motorists and commuters out this evening
through Monday morning need to be prepared for renewed slick spots
on area roads, especially secondary ones that are untreated and
less traveled.
High pressure then quickly builds across the area later monday
with a chilly day on tap despite a return of sunshine. Later
Monday evening, clouds from the next system will move in along
with milder night time temperatures. It does look like a potential
for flurries to affect the area into Tuesday morning with the
approach of the next wx system but any significant wx will hold
off until later that day and night.
For the starting point to the grids the CONSShort and ShortBlend
were used with only minor terrain based temperature adjustments
tonight and Monday night. As for PoPs, beefed them up
significantly for the boundary this evening and then lingering
them a tad longer in the east during the predawn hours Monday
before the upslope shuts off with the high pressure`s arrival.
.LONG TERM...(Tuesday through Sunday)
Issued at 235 PM EST SUN FEB 4 2018
There will be an active weather pattern across the area for the
coming week. Overall the mean upper air pattern continues to be
highlighted by broad troughing over the eastern two-thirds of the
United States with multiple short waves affecting eastern Kentucky
in a split flow pattern. Our area will primarily be affected by waves
in the southern stream, with two systems of note during the coming
week and into next weekend.
The first system will affect the area from Tuesday night into
Wednesday night, with the second system impacting the area from
Friday night into Sunday. While some wintry precipitation will be
possible with each system, latest data and trends point towards most
of the precipitation falling as rain. The best chance for impactful
wintry precipitation will occur in the northern part of the forecast
area Tuesday night before ongoing warm advection results in a plain
rainy day across the entire forecast area for Wednesday. It is
possible a wintry mix of snow, freezing rain and sleet will occur
for a period of time Tuesday night in the north. After a rainy day
Wednesday, colder air will filter back into eastern Kentucky, and
some light snow will be possible across the entire area
Wednesday night.
Temperatures towards the end of the week will be warmer, so that the
system affecting the area next weekend should be almost entirely
rain, though a little light snow will be possible at the onset of
precipitation and possibly again towards the tail end of
precipitation.
One item of note for the coming week is the overall wet pattern with
repeated rounds of precipitation. The 12Z GFS is the most aggressive
model with QPF during the coming week with around 2 inches generated
over parts of the forecast area with the mid week system and around
another 2 inches with the system next weekend. However, this is not
in agreement with the ECMWF or even the GFS ensembles. In fact the
GFS operational run is at the very highest end of the its own
ensembles so its QPF should be regarded with extreme caution. But
even the GFS ensemble mean is generating 1 to 1.5 inches with the
mid week system and another inch or so next weekend. The 12Z ECMWF
is lighter with less than 1 inch for the mid week system and less
than one half inch for next weekend. There is agreement though on a
wet pattern with nearly all precipitation falling as rain during
the coming week in our area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 702 PM EST SUN FEB 4 2018
While we are seeing improving conditions this evening across
eastern Kentucky, a cold front is quickly approaching from the
west. This is expected to blast through us later this evening,
increasing westerly winds to around 10 to 15 knots with gusts up
to 25 knots possible at times. With this boundary, light snow
showers will develop across most of eastern Kentucky this evening
and last into the overnight, especially in the far east. As this
occurs, VIS could drop to at least MVFR to IFR levels with IFR or
lower CIGS. Can`t rule out some breif deterioration to airport
mins in some of the heaviest snow showers overnight. May also see
some icing issues develop on tarmacs late this evening into Monday
morning as temperatures drop well below freezing. Tried to time
out impacts and category chances for each TAF site through the
evening and overnight. Expect snow to depart as quickly as it
arrives, with improving conditions expected after 6Z, along with
calming winds. Skies should scatter out by Monday morning, with
VFR conditions and light winds expected for the remainder of the
TAF period,
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...GREIF
LONG TERM...SBH
AVIATION...JMW
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
357 PM PST Sun Feb 4 2018
.SYNOPSIS...
Dry conditions and above normal afternoon temperatures will
continue through next week. Temperatures will cool slightly early
in the week then warm again late in the week.
&&
.SHORT TERM...(TDY-WED)
Another sunny day today with above normal temps as the state`s
weather continues to be dominated by a large east pac high (582
DM hgts over SoCal) and weak offshore flow at the surface.
Afternoon high temps are again running 10 to 15 degrees above
normal. One record high has fallen so far - at Sandberg.
Expecting the surface flow to turn weakly cyclonic tonight.
Surface pressure gradients will still be lightly offshore (only
about 1 mb), and that shouldn`t be enough to prevent the shallow
marine layer from making it over the LA coast. So shallow, in
fact, that it will likely be accompanied by some dense fog. The
higher resolution HRRR hinting at around 4am over the Long Beach
area.
After the morning clouds burn off in LA County on Monday,
expecting the rest of the day to be sunny. Heights will fall 4-6
DM and this, along with the weaker offshore flow, will probably
mean afternoon temperatures 3-6 degrees cooler than today. A
little coastal eddy spins up on Monday night and this will deepen
the marine layer enough to prevent dense fog as it also pushes
the low clouds into the San Gabriel Valley and the Ventura County
coastal areas.
Aside from the slight increase in morning low cloud coverage
everything else is pretty much the same and expect Tuesday to be
very similar to Monday. Aloft, the flow begins to turn from
northerly to more westerly which will support the winds on
Wednesday.
On Wednesday, high pressure moves over the Great Basin setting up
a moderate offshore scenario. Gusty offshore winds of low-end
advisory strength are likely over the wind prone areas of LA and
VTU Counties. The east pacific high also returns building heights
back up so around the levels seen today (582 DM). The increased
heights and offshore flow will bring 3 to 6 degrees of warming to
the area.
.LONG TERM...(THU-SUN)
Thursday will be similar to Wednesday, but will likely build
another degree or so of warming being the second day of moderate
offshore conditions. Otherwise, little change is expected on
Thursday.
Models begin to disagree on Friday but the differences are not so
great and it looks safe to say that there will be a break down of
the ridge with lower heights as well as less offshore flow.
Afternoon temperatures will dip down the same 3 to 6 degrees they
rose on Wednesday/Thursday. A small marine layer cloud deck may
start to develop for the LA coast.
Still have very low confidence in the forecast for the weekend as
the models are quite different. Both the EC and GFS have a closed
area of high heights (582 DM) off the coast, but the EC is about
450 mi west of LA while the GFS is centered more like 950 miles to
the northwest. The GFS then proceeds to retrograde a cold upper
low over the area to our east - a solution which would bring high
winds but still no rain. The GFS solution remains inconsistent
and an outlier so tended more to the EC.
&&
.AVIATION...04/2356Z.
At 23Z, the marine layer depth was around 400 feet deep at KLAX.
The top of the inversion was around 1300 feet with a temperature
of 22 degrees Celsius.
Low-to-moderate confidence in the current forecast. There is a
chance of sub-VFR conditions between 10Z and 17Z at coastal
terminals and KPRB.
KLAX...VFR conditions are expected throughout the period, except
for a 30 percent chance of sub-VFR conditions between 10Z and 17Z.
VLIFR conditions cannot be ruled out completely.
KBUR...VFR conditions are expected throughout the period. No
notable wind impacts are expected at this time.
&&
.MARINE...04/900 AM.
For the Outer Waters, moderate confidence in current forecast.
There is a 40% chance of Small Craft Advisory (SCA) level winds
north of Point Conception late Monday afternoon through Tuesday.
Otherwise, winds and seas are expected to remain below SCA levels
through Thursday.
For the Inner Waters, high confidence in current forecast. Winds
and seas are expected to remain below SCA levels through Thursday.
For tonight through early next week, patchy dense fog with
visibility under one nautical mile will be possible over portions
of the coastal waters. Confidence is low regarding the exact
location of the fog, but the best chances will be south and
southeast of the Channel Islands, including the waters off Los
Angeles and Orange Counties.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
.HAZARD POTENTIAL OUTLOOK...(WED-SUN)
Advisory level Santa Ana winds with elevated fire weather
concerns possible Wednesday and Thursday.
&&
$$
PUBLIC...jld
AVIATION...Hall
MARINE...Sweet
SYNOPSIS...Kj
weather.gov/losangeles
Area Forecast Discussion
National Weather Service Springfield MO
638 PM CST Sun Feb 4 2018
...Update to Aviation Discussion...
.SHORT TERM...(This evening through Monday)
Issued at 1225 PM CST Sun Feb 4 2018
A quick hitting upper level system with an upper level trough axis
now over eastern KS and northwest MO will move through the region
over the next few hours. High res models weaken forcing somewhat
as it moves in, but could see a quick 1-2 inches with the higher
amounts over the nw quarter of our forecast area. A winter weather
advisory is already out for where we are most confident in road
impacts. We may look at shifting the advisory farther east over
our northern cwfa based on trends.
Webcams/social media indicates that snow quickly accumulates in
our northern counties where the temperature has dropped into the
teens. Expect travel impacts to occur fairly quickly with the
onset of snow.
It will clear out quickly tonight as strong high pressure moves
in. With very dry air moving in, diminsihing winds, and a clear
sky, temperatures might drop quickly where we have some snow
cover, Used colder HRRR guidance for hourly temperatures in the
near term.
Will see a decent recovery in temperatures Monday as winds veer
around to the south late tonight into Monday morning as the sfc
high exits off to the east. The warmest temperatures will be over
the western cwfa.
.LONG TERM...(Tuesday through Sunday)
Issued at 125 PM CST Sun Feb 4 2018
The main concern will be another fast moving winter weather system
Tuesday and Tuesday night.
Tuesday: Another sfc front will move through the area Monday
night as another strong Canadian cold air mass moves south into
the Plains and Midwest. Initially the front will be dry.
A shortwave will move south into the Rockies then eject east into
the central and southern Plains Tuesday. Guidance is in good
general agreement in spreading precip east and northeast into the
area, mainly Tuesday afternoon. The lift/moisture aloft may fight
dry low level air for a time Tuesday. Some warm air aloft would
supports a variety of precip types, snow over the northern cwfa,
snow/sleet/ice closer to the Joplin-Springfield-West Plains
corridor, then mostly just rain along the northwest AR/far
southwest MO border. Travel impacts are expected, but given that
this system will move quickly through, we are not expecting
widespread power line/tree limb issues.
Snow amounts in our model blend range from 2-3 inches over our
northern counties. Amounts farther south along highway 60 are a
half inch to an inch along with some light ice accumulation.
Higher ice amounts of 0.10-0.20 look to be over the eastern Ozarks
in south central MO.
Wednesday-Thursday: Below normal temperatures can be expected
Wednesday. Sfc high pressure will move southeast into the Mid MS
Vly by 12z Thu, then s-sw winds will pick up again with a warming
trend Thursday.
Friday-Sunday: Friday will be a repeat with another cold (dry)
frontal passage late Friday and Friday night. We have less
confidence in precip chances over the weekend with any shortwaves
ejecting ene out of the central/southern Rockies and Plains. The
ECMWF moves drier air more quickly with sfc high pressure versus
the GFS. In either case, we are not looking at a lot precip at
this point. Our blended model forecast will indicate some snow
next weekend, mainly on Saturday. After mild temperatures on
Friday, the front will drop temperatures back below normal for the
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 630 PM CST Sun Feb 4 2018
The accumulating snow that affected the area this afternoon has
spread south of the area this evening. MVFR ceilings will continue
to occur very early in the TAF period but will quickly clear from
north to south this evening as surface high pressures builds into
the area. VFR conditions are then expected the rest of the TAF
period.
Winds will gradually weaken this evening remaining out of the
north. Winds will then become southeasterly by Monday morning.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...DSA
LONG TERM...DSA
AVIATION...Wise
For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
611 PM MST Sun Feb 4 2018
.UPDATE...
Issued at 600 PM MST Sun Feb 4 2018
Made some slight modification to pcpn type for the overnight
period. Given the warmer air aloft moving in from the west, some
freezing rain possible from parts of NE WY into the Black Hills
and SW SD, which will include the Rapid City area...and have
expanded this area of freezing rain slightly from the previous
forecast. Expect any ice accumulations to be very small. Enough
cold air should then rush in by 12Z to end any freezing rain.
&&
.DISCUSSION...(This Evening Through Sunday)
Issued at 219 PM MST Sun Feb 4 2018
Northwest flow aloft continues as the main axis of the upper trough
pushes through the Midwest. Center of arctic high pressure has
pushed southeast of the CWA with return flow just setting up. Warm
air will advect in from the southwest tonight with temps steady or
slightly warming. Upper wave will cross the region tonight with
surface low quickly crossing the CWA. Cooler air will slide back
in from the north. Another round of snow is expected tonight,
however QPF amounts are expected to be much lighter than late
night`s snow. Two inches or less of snow is expected with the
highest amounts over northwest South Dakota. Models indicating the
potential for some very light freezing rain around portions of
northeast Wyoming into the Black Hills area late tonight as 850mb
temps above freezing push in. Any freezing rain will quickly turn
to snow by 12z as the colder air moves back in. Little to no ice
accumulation is expected. Snow will end Monday morning. Cyclonic
flow will continue through the first half of the week with weak
waves crossing the region. This will bring occasional chances for
snow showers to portions of the area. Highs will be in the 20s
most days. Warmer temps will push in toward the second half of the
week. The next chance for accumulating snow will toward the end
of the week as arctic air potentially returns to the region.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 0607 PM MST Sun Feb 4 2018
VFR conditions are expected for much of this evening. MVFR
conditions in light snow will develop around midnight over NE WY
and quickly spread southeast overnight, with some IFR conditions
in heavier snow across NE WY, the Black Hills, and far western SD.
Some light freezing rain also possible from parts of NE WY into
the Black Hills and SW SD. This includes the RAP terminal, but
believe chances are low enough to leave out of the forecast.
Conditions will gradually improve during the day on Monday.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
Update...Johnson
DISCUSSION...13
AVIATION...Johnson