Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/19/21
Area Forecast Discussion
National Weather Service Boston/Norton MA
952 PM EST Thu Nov 18 2021
A strong cold front will then move through Southern New England
tonight, bringing a period of showers. Blustery and colder
weather follows Friday behind this front. High pressure builds
into the region Saturday with less wind, but still cool.
Turning milder Sunday into Monday with an increasing risk of
showers as another frontal system approaches from the west into
Tuesday. Turning colder towards midweek.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
945 PM Update:
Cold front-related rains taking on an anafrontal character as
NW wind shift precedes the rather narrow rain shield. While
spotty intermittent showers now are progressing into central MA
and into Tolland/Windham Counties, steadiest rains still are
back across eastern NY into Berkshire County. Steadiest rains
look to arrive before midnight from central MA/Windham County
westward before midnight, and not into eastern MA and RI between
midnight to 2 AM. Period of steady light to moderate rains
expected for most, though may be some deeper convective
showers/possible rumble of thunder in the southern waters into
Cape Cod/Islands as indicated by recent HRRR runs and the 00z
NAM-3km. This is also where some meager instability may be drawn
northward (LI 0 to -1/CAPE around 150 J/kg). Mentioned mainly
showers here but included an isolated rumble of thunder for
these locations. Even as rain exits, a generous amount of post-
frontal cloudiness won`t favor viewing of the lunar eclipse
tonight. Temps/dewpoints and low temps still look on track so no
changes were made there.
Mostly sunny and warm by mid-November standards this afternoon.
Many locations reached the 70F mark, which although almost 20F
above normal, are still several degrees short of any daily
record. Unfortunately (from the perspective of a warm weather
fan), the warm airmass is not going to linger. A cold front
currently moving into eastern NY will bring more seasonable
temperatures to the region. Timing of the front is roughly 6-7pm
in the CT River Valley, 10 to 11pm in Boston to Providence and
then offshore by 2 AM. Unlike most cold fronts, the bulk of the
clouds and precipitation will be trailing the actual cold front
(called an anafront). Regional radars show the precipitation
band to be about 180 miles wide, so it will take roughly 6 to 8
hours to move through any location. Rainfall, as typical with
these situations, won`t be all that heavy, so looking for
roughly 0.2 to 0.4 inches of total rainfall by the time it ends
late tonight. Temperatures will quickly drop several degrees
when the front moves through, and then continue to fall
overnight. Across the highest elevations of Franklin and
Hampshire County the precipitation might end with a few
snowflakes as temperatures in that area will be into the mid 30s
at that point. By daybreak Friday, most of the area will have
dropped to the mid/upper 30s, except lower 40s hanging on across
Given all the clouds and rain, most of the region will
unfortunately not have an opportunity to view the lunar eclipse.
The only place that might get lucky and sneak a view for the
last part of the eclipse will be in far western part of CT and
MA as the clouds will be starting to break up at that time.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Residual light showers and clouds across the Cape and Islands
first thing will come to an end by 9am. Should work out to a
partly to mostly sunny day for most of the region. Forecast
soundings suggest the boundary layer will deepen up to about
3000 ft by early afternoon. With winds of 25kt to about 30kt at
that level, we should see the surface winds get a little gusty
during the middle of the day. Leaned toward the guidance that
showed the stronger wind gusts to populate into the forecast
grids so expect peak gusts near 30mph. With WNW winds and some
downsloping, I did lean toward slightly warmer guidance for high
temperatures, but with 925mb temperatures around -1C, it`s
going to be tough for anyone to reach 50F. If that happens, it
would probably be on the Outer Cape or Nantucket. Not a lot of
low level moisture, but with the WNW flow moving over the
Berkshires, it should be enough to generate a bit more in the
way of clouds and perhaps a few flurries along the eastern
Friday night should be primarily clear. With high pressure
building over the region, expecting the winds to quickly
diminish. Should be pretty good radiational cooling setup, so
leaned toward some of the cooler guidance. Expect lows pretty
much in the 20s, with low 30s restricted to parts of the Cape.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
* Dry and cool Sat with light winds
* Risk of showers increases late Sun into Mon, with locally
heavier showers possible across eastern New England
* Turning colder Tue/Wed, with a few rain/snow showers possible
Latest guidance suite is in reasonably good agreement with the
overall pattern though Monday. The uncertainty rises after then
with the handling of a mid level trough moving east from the
Pacific Ocean early next week, and how that impacts the
downstream mid level flow. overall, nothing unusual for this
time range of the forecast. Given the sensitivity of the models
to energy over the Pacific, would not be surprised to see
changes to the forecast in the coming days. Early indications
are that Thanksgiving Day across southern New England should be
dry with near to slightly below normal temperatures.
Saturday into Sunday...
Much of this time should be dry with a high pressure moving
across our region. Increasing rainfall chances late Sunday as
this high pressure departs and a cold front approaches from the
west. Should be quite a bit warmer Sunday than Saturday with the
warm advection pattern.
Sunday night into Monday...
This period should be the focus for our next shot at some
precipitation as a cold front traverses our region. Some
questions to how quickly this front moves off to our east.
Should be all rain with above normal temperatures expected.
Tuesday into Thursday...
Have lower confidence in the details for this portion of the
forecast. As of this writing, the GFS was the most bullish on
developing a slower, stronger coastal surface low pressure
beneath a deep mid level trough. While this idea should to be
completely dismissed as a possibility, am favoring the more
progressive solutions as suggested by the Canadian, ECMWF and
UKMET. The mid level pattern is not one where low pressures tend
to linger near southern New England. Thus, favoring a dry
forecast into Thanksgiving, for now. Being a week into the
future, still lots of time for the forecast details to change.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Mainly VFR area-wide. Primary weather maker is a cold front
that is pushing east across NY State at this time. This front
was just on the doorstep of western MA, and should move into
eastern MA about 03-05Z, and then off the coast between 07-10Z.
Expecting a wind shift to the west and ceilings falling to MVFR
levels as this front passes. Widespread showers will occur
along and behind this front. About 6 to 8 hours after the
frontal passage, we should see the showers end with a return to
VFR conditions. So pretty much the entire region should be VFR
prior to 12Z Friday. The exception should be ACK and the outer
Cape, where they will be last to experience this front, however
they too will be VFR no later than 15Z Friday.
Surface northwest winds are expected to gust in the 24-29 kt
range mid day Friday, however VFR conditions will continue.
Winds diminish late afternoon Friday with VFR continuing through
KBOS Terminal...High Confidence in TAF. Timing in TAF has a +/-
1 hour error bar.
KBDL Terminal...High Confidence in TAF. Timing in TAF has a +/-
1 hour error bar.
Outlook /Saturday through Tuesday/...
Saturday through Saturday Night: VFR.
Sunday: Mainly VFR, with areas MVFR possible. Breezy. Chance
Sunday Night: Mainly MVFR, with local VFR possible. Breezy. RA.
Monday: Mainly VFR, with areas MVFR possible. Breezy. Chance
Monday Night through Tuesday: VFR. Breezy. Slight chance RA.
Slight chance SN across the higher terrain.
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Cold front will move across the waters late tonight and first
thing Friday. Expecting gusty northwest winds to develop during
the day Friday, with frequent 25-30kt gusts in the afternoon. As
a result, seas will remain on the rough side. The Small Craft
Advisory currently up for most of the coastal waters into Friday
night makes sense to keep up.
Outlook /Saturday through Tuesday/...
Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
Saturday Night: Winds less than 25 kt.
Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain.
Sunday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Seas up to 5 ft. Rain.
Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 9 ft. Rain likely.
Monday Night: Winds less than 25 kt. Rough seas up to 10 ft.
Chance of rain.
Tuesday: Winds less than 25 kt. Rough seas up to 11 ft. Chance
MARINE...Small Craft Advisory until 1 AM EST Saturday for ANZ231>235-
Small Craft Advisory until 5 AM EST Friday for ANZ230-236.
Area Forecast Discussion
National Weather Service Columbia SC
926 PM EST Thu Nov 18 2021
A cold front with limited moisture moves through the region tonight.
High pressure returns Friday with cool and dry conditions in place
for the weekend. The next front will move through Monday,
accompanied by a better chance for rain. A colder air mass will move
in behind the front for Tuesday and Wednesday, before moderating by
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A cold front is moving into the Upstate at 23z. A few showers
have developed in the Piedmont ahead of the front in area of
weak low level convergence. Moisture remains quite low with
precipitable water near 1 inch just ahead of the
line...suggested by RAP and HRRR. Based on radar, the band of
showers may hold together and move through the northern Midlands
this evening...so raised pops there to chance.
HREF mean has the front moving into the forecast area early
tonight, pushing east of the forecast area after midnight.
A much cooler and drier airmass will move in behind the front
with surface high pressure around 1034mb leading to a tightened
pressure gradient supporting strong cold advection through
tonight as winds shift out of the north and skies clear into
Friday morning. Lows tonight will be in the low 40s NW to upper
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
Clearing skies and cooler temperatures will move in Friday as high
pressure slides into the Mid-Atlantic states. Friday night will be
chilly, but the heart of the cold air mass will slide by to the
north. Still, I expect many locations to get down near freezing,
especially east of I-26 where overnight winds will be lighter and
radiational cooling will be a bit stronger. In areas where the winds
become light, there will be some patchy frost. It is possible that
future shifts will need to issue a frost advisory for areas where
the growing season is till hanging on.
On Saturday, a dry wedge will dominate with the surface high
pressure extending from southern New England down into North
Carolina. Other than some high clouds, skies will be mainly clear,
allowing temps to rebound into the mid 50s to low 60s, just a bit
below normal for late November.
The air mass will start to modify some on Saturday night, but
northern areas could see a pretty quick drop in temps after sunset
under lighter winds. There could be some isolated frost as well, but
temps will only bottom out in the mid 30s north to near 40 south.
Upper level moisture will start to increase on Sunday ahead of the
next system as a reasonably strong jet moves into the mid south. The
air mass will continue to gradually modify, with temps rising into
the 60s despite an increase in clouds. The low levels will still be
to dry to support much in the way of chances for rain until later
.LONG TERM /MONDAY THROUGH THURSDAY/...
On Monday, a deep trof develops at mid and upper levels in the
eastern U.S. This will drag a significant cold front through the
area. Due to the strength of the jet, there will be some moisture
transported northward ahead of the front across the area, with a
chance of showers everywhere. Overall amounts are not expected to be
particularly high with 1/4 inch or less expected. This is due to
both the rapid translation of the system through the area, and the
still relatively limited low level moisture. Global model means have
the area drying our fairly quickly by later in the day on Monday.
The bigger story Monday will be the significantly colder air mass
behind the front. Winds will be on the increase, and strong low
level cold advection will keep temps in the 50s all day, and breezy
conditions will make it feel even cooler.
Monday night will be a quintessential cold advection night with
northerly winds bringing down anomalously cold low level air,
with 850 temps up to 10 degrees C below normal. Lows will bottom
out a little below freezing everywhere despite the wind staying
The cold air mass will remain in place Tuesday with max temps
struggling to get much above 50 despite quite a bit of sunshine. The
winds will die down Tuesday night as the surface high pressure area
moves nearby, with the coldest night of the season so far expected.
Lows will get down to the mid to upper 20s by Wednesday morning, a
hard freeze for many.
A slow moderation in temps is expected Wednesday and Thursday as
high pressure slides south of the region.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
A cold front will come through tonight. Associated band of
showers along and ahead of the front expected to dissipate later
this evening with loss of heating, without significant upper
energy to work with. Some breaks in the cloud cover and light
winds this evening ahead of the front could provide some fog
potential at AGS/OGB. Otherwise, later tonight, drier low level
air will enter the region behind the front and winds will shift
to NNW and stay up some, which is expected to preclude fog. VFR
Friday with winds veering to NE.
EXTENDED AVIATION OUTLOOK... VFR Friday night/Saturday, with
some stratus potential late Saturday night/early Sunday.
Restrictions may occur on Monday ahead of the next front, with
breezy conditions behind the front on Tuesday.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
603 PM CST Thu Nov 18 2021
A very persistent area of light rain showers continues to creep
toward the north over Maverick and Zavala Counties. Short term models
show this dissipating over the next few hours. We have updated the
forecast to keep slight chance POPs for a little while longer.
.PREV DISCUSSION... /ISSUED 522 PM CST Thu Nov 18 2021/
Northerly to northeasterly winds continue this evening, but they are
beginning to weaken. This trend will continue for the next few hours.
VFR ceilings at all terminals will remain into the evening. There
will be gradual clearing from east to west. Winds will shift to
easterly late Friday morning.
PREV DISCUSSION... /ISSUED 205 PM CST Thu Nov 18 2021/
SHORT TERM (Tonight through Friday Night)...
Gusty north winds are in place across all of south central Texas as
of early this afternoon. The 24 hour temperature change plot shows
readings are a solid 15-25 degrees colder than this time yesterday.
Some lingering convection mainly in the form of showers is also
noted across the Winter Garden region eastward into the I-37
corridor south of San Antonio. The last few HRRR runs latch on to
this activity and show it persisting into the late afternoon hours.
Earlier convection across western Edwards county was lingered longer
than anticipated and produced some 1/2" to near 2" amounts along FM
674. Some amounts near 3/4" are also noted over far southwest
The main concern for tonight will be the low temperature forecast.
We have plenty of clouds in place as of now, but we do expect a
gradual thinning of cloud cover across most of the region. The lone
exception will be across the Rio Grande plains into portions of the
southern Edwards Plateau where southerly flow develops around 850mb,
leading to continued low cloud cover. Forecast soundings as far
north as Austin also show a thin layer of moisture remaining in
place overnight around 850mb. We do expect dry air to remain in
place and near surface winds will eventually decrease. However, wind
speeds around 925 mb will not drop off and this may keep some mixing
going in the boundary layer overnight. Numerical MOS has also
trended upward for overnight lows tonight. Current thoughts are the
best chance for any near freezing temperatures would remain locked
up in the Hill Country in low-lying areas such as river bottoms and
creeks. With this in mind, we will issue a Special Weather Statement
highlighting near freezing temperatures in low-lying areas across
the Hill Country.
Morning cloud cover lingers across the Rio Grande plains, then
decreases during the afternoon hours. All areas can expect mostly
sunny skies tomorrow afternoon along with highs in the 60s.
Southerly winds in the low-levels will return to all areas Friday
night, with overnight lows in the mid 40s to lower 50s.
LONG TERM (Saturday through Thursday)...
Breezy southerly flow will be in place on Saturday ahead of the next
system. This trough axis will be moving into the Central Plains with
a deepening surface low near the Panhandle. This low will move to
the east by Saturday night sending the next cold front into South-
Central Texas during the day on Sunday. There should be enough
moisture for a slight chance of showers and perhaps an isolated
thunderstorm with the frontal passage across the eastern and southern
zones, but this should be another front without appreciable
rainfall. Temperatures ahead of the front on Saturday will be in the
70s with some 80s possible in the southern counties on Sunday before
the FROPA. Behind the front, temperatures should be in the 60s to
lower 70s on Monday. Dry weather with a slight warming trend can then
be expected through Wednesday. The forecast then becomes a bit more
uncertain. The GFS and ECMWF both show a cut-off low to our west
Thursday with a frontal boundary somewhere in the Southern Plains.
This pattern has a chance to bring widespread rainfall and cooler
temperatures at some point in the Thursday to Saturday timeframe next
week. However, how much rain and how cool temperatures get is very
uncertain at this time.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 42 65 48 74 60 / 0 0 0 0 0
Austin Bergstrom Intl Airport 41 65 45 74 58 / 0 0 0 0 0
New Braunfels Muni Airport 44 66 46 76 58 / - 0 0 0 0
Burnet Muni Airport 38 63 47 73 58 / 0 0 0 0 0
Del Rio Intl Airport 47 70 50 78 57 / 20 0 0 0 0
Georgetown Muni Airport 37 64 46 73 58 / 0 0 0 0 0
Hondo Muni Airport 44 68 47 76 58 / 20 0 0 0 0
San Marcos Muni Airport 42 65 45 75 58 / - 0 0 0 0
La Grange - Fayette Regional 44 65 47 76 61 / 0 0 0 0 0
San Antonio Intl Airport 45 66 49 74 60 / 10 0 0 0 0
Stinson Muni Airport 48 68 51 77 61 / 10 0 0 0 0
Area Forecast Discussion
National Weather Service Marquette MI
528 PM EST Thu Nov 18 2021
.SHORT TERM...(This evening through Friday)
Issued at 410 PM EST THU NOV 18 2021
Water vapor imagery and RAP analysis show a mid-level trof extending
from Hudson Bay to the western Great Lakes. Under 850mb temps of -8
to -11C, LES is ongoing off Lake Superior under w to wnw low-level
flow. A sfc trof is dropping s across Lake Superior. The combination
of increasing convergence vcnty of the trof and deepening moisture
profile to 15kft or so has led to an increase in LES during the day
today. Overnight snowfall across the w was on the light side, but
during the day today, webcams/radar imagery have indicated heavier
LES. Webcam near Nisula suggests at least 2-3 of inches of snowfall
in that area late morning to the current time. All of the other avbl
webcams across the w indicate much less snowfall today. To the e,
heavier LES organizing along the trof is just now moving onshore
across the eastern fcst area.
As a sfc trof moves s over the next few hrs, expect a good burst of
snow to push inland across Alger/Luce/northern Schoolcraft counties.
NW flow LES will then organize in its wake. With a deep moisture
profile to around 15kft thru the evening, expect mdt to briefly hvy
LES in that area. Moisture depth will diminish during the overnight,
but it appears bands tied to Lake Nipigon preconditioning will
probably affect portions of Luce County. As a result, greatest snow
accumulations by daybreak will likely end up there. In general,
expect snow accumulations of 2-5 inches across Alger/Luce/northern
Schoolcraft counties. Bands will extend into southern Schoolcraft
and should result in snow accumulations of 2-4 inches there,
greatest n and e of Manistique. LES will temporarily increase into
Gogebic/Ontonagon counties over the next few hrs as winds shift more
to the nw, but accumulations won`t warrant an advy. Sfc high pres
ridge will reach far western Upper MI before sunrise, so there may
be an opportunity for skies to at least partially clear out to allow
temps to fall into the teens F. Otherwise, expect 20s for lows
Sfc high pres ridge will quickly shift e across the fcst area on Fri
and will be e of the area by late aftn. Lingering LES into the
eastern fcst area will end as winds back around to an offshore
direction. Any additional snow accumulation should be less than 1
inch. Although lake stratocu will clear out w to e with passing high
pres ridge, considerable high cloudiness will already be
overspreading the area under developing waa regime in response to
next shortwave moving across s central Canada. Expect highs in the
30s F across the board.
.LONG TERM...(Friday night through Thursday)
Issued at 415 PM EST THU NOV 18 2021
The extended period is expected to start out dry across the area as
a weak zonal pattern aloft begins to set in. However, height falls
at the sfc, southwesterly winds with limited shear aloft, and a
delta-T around 13F between the water sfc of Lake MI and the top of
the inversion layer Friday night could bring some light lake-effect
showers over the far east near Schoolcraft and Luce Counties.
Expecting rain to be the primary precip type, but leaving in a
slight chance for snow as perhaps it`s possible should ice crystals
form (this is based on the assumption that if the dry layer in the
lower levels is overcome, temps in the atmospheric profile could
cool enough to allow snowfall). Otherwise, besides some breezy
conditions on the downslope areas near Lake Superior, expect quiet
weather Friday night. This quiet weather should continue into
Saturday, although there is a slight chance for some light rain
showers far east as there may be enough forcing and moisture
transport to overcome the dry layer near 800mbs.
Starting Saturday night, another Clipper system looks to dig off of
the Rocky Mtns and move into Northern Plains. This system looks to
bring a strong cold front across the area Sunday into Sunday night.
Also, a shortwave in the Southern Plains Saturday night looks to
lift northeast towards the Upper Great Lakes, arriving late Sunday.
As these two shortwaves phase, we could see some precip move across
the entire area, namely over the northwest wind lake-effect belts
from Sunday afternoon to Sunday night. While I`m expecting rain to
be the initial precip type in the east Sunday, could see some snow
mixed in further west along and behind the cold front of the Clipper
system. Could definitely see some lake-enhancement in the northwest
wind lake-effect belts Sunday night as delta-Ts look to get into the
mid-teens. As the phased low moves out of our area Monday, expect
the transition to pure lake-effect snow in the north/northwest wind
lake-effect belts. Overall, wouldn`t be surprised if we need to
issue some winter weather headlines for the northwest wind lake-
effect areas Sunday night into Monday, as there could be quite a few
inches of high SLR snow. Expect the lake-effect snow to end Monday
night and Tuesday as a ridge changes the winds and warms the area.
Could see another quick break from precip Tuesday as the ridge peaks
over us. However, another shortwave from Alberta looks to move over
us sometime around the middle of next week. It looks possible for
another Alberta Clipper system to move over Upper MI around
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 528 PM EST THU NOV 18 2021
Lake effect shsn will continue off Lake Superior into tonight under
w to nw winds. Under these conditions, expect MVFR conditions to
prevail at IWD. Early Fri morning, VFR conditions will return to IWD
as passage of a sfc high pressure ridge axis shifts lake effect
shsn/stratocu to the ne of the terminal. At CMX, MVFR conditions
should mostly prevail into Fri morning. Some brief periods of IFR
vis in shsn will occur this evening. Passage of a sfc high pressure
ridge will bring a return to VFR. WNW winds at CMX will gust to
around 30kt into the early evening. At SAW, VFR conditions will
continue into Fri.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 419 PM EST THU NOV 18 2021
Northwesterly gale-force gusts up to 40 knots are expected to
continue across the east half of Lake Superior tonight while any
lingering gale gusts to 35 knots across the w end this evening.
After a brief period of lighter winds under 20kt associated with
passing high pres ridge Fri morning, winds will begin to increase
again from w to e in the aftn/evening. Sfc pres falls are
expected to bring south to southwesterly winds up to 30 knots
Friday night. Winds should diminish to 20 knots or less by
Saturday. Winds should remain that way until Sunday afternoon, as
a Clipper system is expected to bring north to northwesterly gale-
force gusts up to 40 knots across the lake Sunday night through
Monday. Light freezing spray is possible as this system passes the
lake, even into Monday night. By Tuesday, winds are expected to
become 20 knots or less again.
Winter Weather Advisory until 7 AM EST Friday for MIZ006-007-085.
Winter Weather Advisory until 7 AM EST Friday for MIZ014.
Gale Warning until 3 AM EST Friday for LSZ249>251-265>267.
Gale Warning until 1 AM EST Friday for LSZ243-244-264.
Gale Warning until 8 PM EST /7 PM CST/ this evening for
...Update to aviation forecast discussion...
Issued at 228 PM CST Thu Nov 18 2021
At 20Z this afternoon, the forecast area finds itself within
northwest flow aloft as the upper trough moves east of the MS River
valley toward the northeast US. While we are still pretty dry in the
low and mid levels, water vapor imagery shows moisture within the
low-amplitude ridge across the Intermountain West, which will lead
to increased cloud cover tomorrow. A weak trough is noted off the
Pacific coast. Meanwhile at the surface, high pressure is centered
over KS and OK and has led to much lighter winds from the northwest
compared to yesterday. This along with neutral temperature advection
has kept temperatures on the cooler side in spite of sunny skies. We
look to remain mostly clear during the overnight hours aside from
some thin cirrus ahead of the bulk of clouds moving in Friday. Low-
level winds turn back to the south tonight and should prevent temps
from dropping off as much as this morning, although it still looks
chilly around 30 degrees to start the day.
By morning, the surface high pushes east with a deepening lee trough
in the High Plains, and a 40-50 kt LLJ looks to develop over central
KS as well. This leads to slightly warmer temps and another windy
day to end the work week. The pressure gradient is progged to
tighten to 7-9mb across the area, and forecast soundings show mixing
up to 900mb. There seems to be a general consensus for sustained
winds of 15-25mph with gusts of 30-40mph, peaking around midday. The
12Z/18Z HRRR runs as well as the 15Z RAP suggest a brief period mid
to late morning when gusts could reach advisory criteria, which
seems plausible if winds pick up quickly enough and we can tap into
the LLJ before it diminishes. However, am not confident that it
would be widespread enough or long enough in duration to warrant a
headline at this time. That being said, winds do look strong enough
for a brief window of very high fire danger around midday. Think
there should be enough cloud cover with increasing low-level
moisture (RH in the upper 20 to low 30 percents) to preclude any
headlines there as well, but conditions still don`t look conducive
for burning given the strong winds.
The pressure gradient slowly relaxes heading into Saturday with the
surface low pushing south into the OK/TX panhandles, so winds should
be lighter with highs a bit warmer in the mid to upper 50s. The
aforementioned Pacific trough moves across the Rockies during the
day, setting the stage for a weak frontal boundary to bring our
temperatures down slightly for Sunday. The bigger cool-down comes on
Monday as the Canadian trough swings through the Upper Midwest and
brings stronger CAA into our area. A more amplified ridge quickly
moves across the area on Tuesday to bring temperatures up again
before a more notable mid-week system. Precip chances look tough to
come by, as that system is really our only shot this forecast period
and chances are small as of now - looking better toward MO.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 527 PM CST Thu Nov 18 2021
VFR prevails at KTOP/KFOE/KMHK as light winds back to the south
overnight in response to a deepening system over eastern CO. A
45 to 50 kt LLJ jet develops over central KS, possibly impacting
KMHK aft 11Z. Model soundings are inconsistent in the magnitude of
the marginal LLWS, and given that its speed shear with increasing
sfc winds anticipated, decided to leave out the mention.