Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/22/22
Area Forecast Discussion
National Weather Service Dodge City KS
439 PM CST Mon Feb 21 2022
...Updated aviation section...
.SHORT TERM...(This evening through Tuesday)
Issued at 224 PM CST Mon Feb 21 2022
A cold front is moving southward across the area this afternoon. The
high at Hays has already been reached for the day and falling
temperatures are likely for the rest of the afternoon, as a large
region of intense 850 mb level cold advection continued a
southward trajectory across nw KS into CO. A warm nose of air in
a downslope environment will continue to promote rising
temperatures across the southernmost reaches of the DDC forecast
area, with upper 70s still likely by the late afternoon hours.
Interestingly, locally at DDC, the HRRR shows about a 15-20F
degree drop in temperature (mid 70s to mid 50s) between 4 and 5 pm
this afternoon, coincident with the frontal passage and declining
sun angle.
Attention turns Tonight to apparent temperatures by early Tuesday
morning. There already is a wind chill advisory across roughly the
northern half of the forecast area as temperatures plunge behind the
cold front and north east winds gain strength overnight into the 20
knot and up range, sustained. Medicine Lodge could see a drop from
as warm as 80 degrees this afternoon, to freezing by midnight.
The wind chill advisory are still looks good, and will run through
late morning Tuesday. A minor adjustment to increase a county or two
can`t be ruled out yet with 00 model runs coming up this evening.
The true cold air continue to settle into the area on Tuesday night
into Wednesday. Overwhelming model consensus support highs reaching
the 20s over most of the area with a minority of the mesoscale
(NAMBC/HiResARW) supporting even colder, maybe under stratus,
temperatures across the northern third to half of the areas,
relegated to mid/upper teens. The current forecast represents the
colder solutions pretty well.
.LONG TERM...(Tuesday night through Monday)
Issued at 224 PM CST Mon Feb 21 2022
Currently drawing up another wind chill advisory to cover the
period from middle of the evening Tuesday though mid morning
Wednesday as combined temperature (probably colder this night) and
surface wind drive apparent temperatures to around the -15 degree
and colder threshold, area - wide. February normally speaking is
a tale of 2 halfs with respect to record minimum temperatures. The
1st half (we`ll say through the 16th) historically has lows from
-10F to -26 F, while the second half of the month (17th onward)
ranged in the negative single digit and positive single lows. At
this point the fifth percentile NBM forecast, which might be the
coldest we could expect is -4F and all of the model and MOS
guidance right now is well above that statistically, where lows
around 1 above are near the 50th percentile. Still the apparent
temperatures will be significant, probably pushing or exceeding
-20F for a period early in the hours before sunrise Wednesday as
northeast winds persist from the but winding down still to around
10 knots at sunrise.
From a model perspective, looking at lows though the week, it`s
clear the arctic air settles in over the high plains and will be
quite slow to modify/erode. For instance the ECMWF MOS and daily
Raw Model consensus output all show single digit lows through
Friday morning , and still quite cold teens into the weekend.
Likewise, winter like highs moderating upward toward freezing
through the "workweek" before a trend to more normals highs is
possible by the upcoming weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 436 PM CST Mon Feb 21 2022
The strong cold front will continue to sag south with high
pressure building across western Kansas. This will lead to the
strong northerly winds to continue through the overnight period.
Some low clouds are expected to filter into the HYS terminal
overnight with a few hour period of low clouds possible around the
DDC terminal. Otherwise expect VFR conditions.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 6 22 1 24 / 0 0 0 10
GCK 6 21 0 23 / 0 0 0 10
EHA 10 26 3 26 / 0 0 0 0
LBL 9 27 1 25 / 0 0 0 10
HYS 5 18 -1 21 / 10 0 0 10
P28 13 28 4 27 / 0 0 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory from 2 AM to 11 AM CST Tuesday for KSZ030-
031-043>046-063>065.
Wind Chill Advisory from 9 PM CST /8 PM MST/ Tuesday to 10 AM
CST /9 AM MST/ Wednesday for KSZ030-031-043>046-061>066-074>081-
084>090.
Red Flag Warning until 6 PM CST /5 PM MST/ this evening for
KSZ061>063-074>081-084>090.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Hovorka42
Area Forecast Discussion
National Weather Service Grand Rapids MI
756 PM EST Mon Feb 21 2022
LATEST UPDATE...
Update
.UPDATE...
Issued at 756 PM EST Mon Feb 21 2022
We (Brandon and I) have decided to add Muskegon, Kent and Ionia
Counties to our Winter Weather Advisory. The latest observations
from both mesonet, ASOSs and AWOSs all show at or below freezing
temperatures from near and north of I-96 from just east of
Muskegon to Grand Rapids (at 32F) to south of Ionia (31F) . The
precipitation is starting to develop over central Wisconsin into
SE Minnesota as I am writing this. This area is expected to expand
significantly in coverage over the next few hours and should
reach southwest Michigan prior to midnight. This will all be rain
overnight as it is warm enough aloft for rain. The latest runs of
the HRRR and RAP model and the 18z NAMnest show temperatures near
to below freezing most of the night over the northern parts of
Muskegon, Kent and Ionia Counties. It just seems prudent to issue
this Advisory before the precipitation begins.
&&
.DISCUSSION...(This evening through next Monday)
Issued at 320 PM EST Mon Feb 21 2022
- Freezing rain risk into Tuesday
The latest runs of the models show the northeast parts of the CWA in
a zone for freezing rain starting up tonight and continuing into
part of Tuesday. Forecast soundings show temperatures slightly
below freezing with a noticeable warm layer aloft. The main
question is how long of a duration will it last and whether we
will see more than a quarter in of ice. The latest High Res Euro
shows the duration of the freezing rain to be limited with the
model taking the above freezing temperatures through the northern
zones by 13z Tue or so. The trend is for a sooner arrival of the
above freezing temperatures and slightly higher values for the
northern zones. Based on this we will keep amounts a quarter inch
of less and the headline as an advisory. However...trends will
need to be monitored closely for this event as just north of our
CWA the below freezing temperatures persist. Any southward shift
of this zone would warrant an ice storm warning headline. The
southern edge of the freezing rain risk is somewhat uncertain as
well...with the cities of Muskegon to Grand Rapids and Lansing
very close to the possible impacts. Basically the thermal gradient
will be tightening up on top of the CWA as the wave of low
pressure moves in from the southwest. For Kent County the
northeast sections of the county stand the greatest chance for
seeing freezing rain and local impacts. Right now that is expected
to occur in the middle of the night with surface temperatures
rising to above 40 degrees by daybreak. Thus the window for
freezing rain will be of a short duration if it happened at all
for Kent County. Thus we will not expand the winter weather
advisory further south. Again...close monitoring will be needed.
- Thunderstorm risk late tonight into Tuesday.
Elevated instability moves in during this window as a southerly low
level jet of 30 to 40 knots advects Gulf moisture in. Mid level
lapse rates approach 8.5 deg C/km around 07z to 10z for the southern
parts of the CWA. Also a mid level shortwave will be moving in from
the southwest Tuesday morning which will generate some lift. Thus we
have expanded and increased the thunder risk in the forecast mainly
for the southern half of the CWA.
- Period of snow for Friday
An 850 mb wave of low pressure is shown by the High Res Euro to
track northeastward through southern parts of the CWA Thursday night
into early Friday. Forecast soundings support snow with this system.
The lift remains relatively weak which will act to keep the snow on
the light side. ECMWF ensemble 24 hr snowfall amounts for this event
show the members huddled around 1 to 2 inches for Grand Rapids and a
little higher for Jackson.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 647 PM EST Mon Feb 21 2022
The low clouds are spreading in from the northeast to the
southwest this evening as the cold air tries to penetrate farther
south. I expect all TAF sites should be mvfr with cigs by 06z or
so. I would expect IFR cigs/vsby at most if not all TAF sites
between 09z and 21z Tuesday.
There is the treat of freezing rain at both GRR, MKG and LAN early
tonight (03z to 09z). It is a question of how quickly the
precipitation starts verses how long it takes for the incoming
warm front to push surface temperatures back up. At this point I
believe the freezing rain will stay just north of I-96 TAF sites
but we will keep a close eye on this.
Overnight, it seems more of a drizzle sort of and event as there
is not deep moisture. The deep moisture and instability arrive
prior to sunrise on Tuesday. Locally heavy rainfall and a few
thunderstorms are possible during that time frame.
Expect low level wind shear overnight as there is 40 to 50 knots
in the 2000 to 5000 ft AGL layer tonight.
The bottom line is flight conditions will be best during the next
2-5 hours and after that will become challenging due to low
ceilings, possible thunderstorms and in the 03z to 09z time frame
the threat of freezing rain for the I-96 TAF sites.
&&
.MARINE...
Issued at 320 PM EST Mon Feb 21 2022
We will maintain the small craft advisory. Gusty east to northeast
winds tonight will shift to the northwest by Tuesday night. The will
remain up over 15 knots and that will lead to hazardous boating
conditions for small craft.
&&
.HYDROLOGY...
Issued at 320 PM EST Mon Feb 21 2022
There are a couple of hazards to monitor for the rivers over the
next couple of days. One is the ice jams and existing ice in the
rivers. The crest on the Grand is approaching Grand Rapids this
evening. There was still a decent amount of ice in the river around
Comstock Park where minor flooding was ongoing. Any movement of this
ice could result in sudden water level changes.
Further downstream the ice had jammed up downstream of Robinson
Township causing some water to back up behind it. This in
combination with the approaching crest coming down the Grand has led
to some flooded roadways. That will continue into Tuesday.
Next up is the heavy rain risk for tonight into Tuesday. Some high
res models like the HRRR were showing a swath of over an inch of
rain through the heart of the CWA. Other models were more
conservative with amounts closer to a half inch. Given the risk for
convection and Gulf moisture advecting in...we do stand a chance to
see those higher amounts. While that is not the most likely scenario
with the warm front to feature some northward movement with
time...if it stalls out...we could see a period of training
convection and heavy rain. We will issue a hydrologic outlook for
this potential event.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 7 AM EST Tuesday for MIZ050-057-
058.
Winter Weather Advisory until noon EST Tuesday for MIZ043>046-
051-052.
Winter Weather Advisory until midnight EST Tuesday night for
MIZ037>040.
Flood Watch through Tuesday afternoon for MIZ056.
LM...Small Craft Advisory until 4 AM EST Tuesday for LMZ846>849.
&&
$$
UPDATE...WDM
DISCUSSION...MJS
AVIATION...WDM
HYDROLOGY...MJS
MARINE...MJS
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1032 PM EST Mon Feb 21 2022
.SYNOPSIS...
Warmth today will be replaced by cooler temperatures tomorrow
with a threat of some wintry precipitation before a change to
all-rain. Warmth returns with a vengeance on Wednesday as
temperatures soar through the 50s into the lower 60s. More
snowmelt and rain could lead to ice jamming issues over the
interior as a result. High pressure builds in from Canada
Thursday, then a snowy system crosses southern New England on
Friday bringing a good chance of a plowable snow for much of the
region. Cooler and quiet weather is expected this weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
1030PM Update: Temperatures remain highly variable as of 10pm
with some spots falling into the mid 20s...with a few spots
where winds have remained coupled sitting in the mid 30s. Have
adjusted near term temperatures to match this trend...but no
significant changes to overnight lows. Fairly substantial cloud
cover for about the northern half of the forecast area. Clouds
remain at or above 5kft...with any threat of drizzle/etc holding
off until the morning hours Tuesday.
620PM Update: Going forecast looking good as of 6pm. Some spots
have cooled pretty quickly given sunset and decoupling...and
have lowered temperatures in these areas for the next few hours
as a result. Otherwise...no significant changes to the forecast
at this time.
Previous Discussion below...
Overall a pleasant evening in store with clouds remaining over
the higher terrain and spilling into the foothills. A lot of
impressive temperatures today, but warmer values will be in
store for Wednesday, discussed below.
Clouds should remain fairly thin early on tonight, with
temperatures dropping this evening. Do expect clouds to thicken
towards morning amid WAA and moisture advection. However at the
surface, light NNE winds will tap into cold air near the Quebec
border, filtering into the higher terrain and mtn valleys. Model
guidance has been quite strong with this infiltration,
especially after a warm day Monday. Low temps in the teens can
be expected in the northwestern tiers of counties in Maine, with
lower to mid 20s along the foothills.
Meanwhile, moisture will pool at the surface while dry air
remains aloft. This will create the chance for some drizzle
early Tues morning, some of which may contribute to slick
surfaces before temps along the coast increase.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
Freezing rain expected inland Tuesday before changing to rain
in the late afternoon and evening amid a strong warm surge.
Drizzle and freezing drizzle will be possible region wide
through Tuesday morning, with the freezing component mainly in
the western terrain. While the low levels will be saturated
amid a temp inversion, some remaining dry air at the surface may
temper these drizzle chances until more steady precip arrives
in the afternoon.
HRRR and NAMnest temps overnight plunge freezing temps through
southern Maine and NH come Tuesday morning. This is a much
cooler trend, and will need to watch overnight temps and early
morning temps. If cooler air does make it to the coast, slick
roads may become more a threat here for the early/mid afternoon
due to freezing drizzle or freezing rain onset.
For the interior, the cold air will be much more difficult to
scour out, resulting in the onset of more steady precip in the
afternoon falling as freezing rain. Have issued a Winter Weather
Adv in these locations, beginning with a potentially tight temp
gradient from shore to foothills, and into the western
terrain/NH. Precip will change to rain south to north through
the evening hours, but have run the Adv until 11pm if northern
areas lock in for longer.
Greatest QPF is forecast to fall in the higher terrain and
convergence over the foothills. Ice totals could approach two
tenths of an inch, but expect most locations to measure lower
than this. Power outages should be limited due to ice, however
SE winds do increase as the transition to rain occurs. Some
gusts to 30 cant be ruled out, but lower than 25 mph is most
likely. With rain and rising temps moving in, ice cling should
be short lived, particularly from the coastal plain into the
foothills.
See hydrology section for more on QPF and warm air impacts on
area hydrology.
Precip will taper early Wed morning, with just a few rain/snow
showers occurring in upslope areas Wed afternoon/evening. The
main talking point will be temperatures surging within a broad
warm sector. Highs towards the lower 60s will be possible across
southern NH and up portions of the ME coast. Temps will begin to
crash during the evening as the main low finally clears into the
Maritimes with NW winds flushing into the region.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Overview... Cool Canadian high pressure pushes into the region
for Thursday, in the wake of the midweek system. Meanwhile a
zonal jet overhead contributes to cyclogenesis over Appalachia
with a trough digging down through the Mississippi valley...
lifting toward the northeast late in week. These will bring us
significantly cooler weather, a bit closer to normal anyway,
with snow expected for Friday. The weekend looks similarly cool
with quiet weather, except for a cold front crossing around
Sunday or Monday.
Starting Wednesday night... upslope snow showers and clouds will
dwindle amid pressure rises from the west. Temperatures will be
significantly cooler on Thursday, with t850 taking a 15-20 degree C
tumble in around 24 hours over the region, so even with good mixing
under mostly sunny skies afternoon highs are still progged to be
mostly in the 20s and 30s. Cool northerly flow will set the stage
for a snowy system set to arrive by Friday.
For that snowy system... by Thursday evening, cloud cover will be on
the increase as low pressure matures over the Tennessee and Ohio
River Valleys. Driven by a shortwave trough lifting NEward over the
eastern CONUS...ensemble and deterministic consensus brings the low
near the southern New England coast, merging with a coastal low, and
vastly simplifying the precipitation type forecast for our
area. Medium-high confidence exists that all-snow will dominate
over our forecast area with a cool ageostrophic feed from
Canada... only reason it isn`t high at this juncture is because
we`re a few days out yet and entire numerical suites have been
known to shift, and the 0C isotherm for maximum Ts aloft does
into Mass.
The main question then turns to amounts. Classic ingredients will be
in place given the maturity of the storm by the time it reaches New
England with broad ascent associated with its frontogenetical
circulation, shoved along by the parent trough`s stratospheric
intrusion. The storm is expected to be progressive, but its track as
it emerges into the Atlantic may allow good forcing to pivot near
the NH/Mass border and prolong snowfall. The GEFS and ENS... along
with their deterministic controls... have good potential for 1+ QPF
over southern zones which, given climatologically average ratios,
would give a foot or more of snow. There`s strong likelihood of
a plowable snow over the southern third or so of the forecast
area. Those amounts will taper toward the north, which is the
main source of uncertainty... current indications bring just a
couple inches near the international border. We`ll be on the
northern side of forcing, which would likely lead to a drier and
potentially fluffy/higher ratio snow. Snow like this can easily
blow around and lead to poor visibility, that said wind fields
aren`t expected to be particularly strong. For timing, have
light snow breaking out Friday morning with heaviest accums
during the midday and afternoon... exiting out over the waters
through the evening. This scenario would significantly impact
the Friday evening commute as well as travel to recreational
areas for the weekend.
Beyond this storm, quiet zonal flow takes over through much of the
weekend with a more sunny mix of sun and clouds and a ridge of high
pressure crossing. Saturday highs will likely land below average, in
the teens to near 30... then increasing southwesterly flow behind
the ridge axis leads to a slight warmup on Sunday with near-normal
highs in the 20s and 30s. Models are in decent agreement bringing a
cold front across sometime late Sunday / early Monday. What happens
around this FROPA is still a bit up in the air; one interesting
scenario has this phasing with a coastal low, amplifying near our
coast, and bringing another round of snow as opposed to only a
smattering of snow showers mostly over the mountains. An Arctic
airmass comes in the wake of this cold front, but there is some
disagreement for how far south this eventually reaches...
nonetheless the trend to start the next work week will be a cool one.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Short Term...
Summary: A cold front sagging south into the region tonight will
slowly push north as a warm front on Tuesday night bringing lowering
clouds and the chance for drizzle/freezing drizzle on Tuesday
followed by a period of rainfall Tuesday night.
Restrictions: VFR conditions likely through the predawn hours before
CIGS being lowering with MVFR CIGS likely by daybreak with further
deterioration to LIFR/IFR CIGS/VSBYs by late Tuesday and Tuesday
night.
Freezing Precip: There is some potential for patchy freezing
drizzle LEB-HIE-AUG Tuesday morning. By afternoon the potential for
precipitation will increase while temperatures warm. Have not
included mention of FZRA in this TAF set but by late afternoon there
is that threat...esp at AUG. Will await better confidence in the
guidance.
Winds: Winds will become light northeast overnight...remaining less
than 10kts. These light northeast winds will continue through the
day on Tuesday before shifting out the south and increasing to 10-
20kts Tuesday night with gusts 25-30kts PSM-PWM-RKD-AUG Tuesday
night.
LLWS: No LLWS is expected through Tuesday. Tuesday evening...2kft
southerly winds increase to 35-45kts which will likely necessitate
LLWS in the TAFs beyond 00Z Wednesday.
Long Term...VFR prevails with light NWerly flow on Thursday.
CIGs will lower and SN breaks out across southern and western
terminals Friday morning, spreading north and east and leading
to significant restrictions through the day. IFR to LIFR is
likely during this period along with northeasterly winds gusting
to as high as 20-25 kts along the coast. Conditions improve to
VFR as the system pulls away Friday night into Saturday.
&&
.MARINE...
Short Term...Some remaining waves around 5 ft possible this
evening, but overall subsiding below SCA criteria. A quick wind
increase from the SE Tues afternoon will result in Gale
conditions overnight and early Wed morning. Another wind shift
is expected Wed evening becoming W then NW as low pressure
passing north of the waters and into the Canadian Maritimes.
Long Term...Seas and winds will gradually diminish Wednesday
night with high pressure building in for Thursday. Northeasterly
winds will pick up Thursday night ahead of approaching low
pressure, leading to another period of SCA conditions through
Friday with widespread snow. Low pressure is expected to pass
just south of the waters with winds taking a northerly clip late
Friday. High pressure builds in for the weekend with winds
gradually diminishing and turning westerly.
&&
.HYDROLOGY...
River levels remain elevated from melt/precip last week after a
few cooler days to temporarily freeze new ice movement. The
incoming precipitation Tues afternoon will add to hydro system
stressors, particularly for a combination of warm snow temps,
significant SWE, and prior jamming/releases. Have issued a
Flood Watch where greatest confidence exists for ice jam issues;
northern/central NH and far west ME. Expansion may be needed
eastward with time and confidence.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Flood Watch from late Tuesday night through Thursday morning
for MEZ007-012.
Winter Weather Advisory from 1 PM Tuesday to 1 AM EST
Wednesday for MEZ007>009-012>014-018>021-033.
NH...Flood Watch from late Tuesday night through Thursday morning
for NHZ001>007.
Winter Weather Advisory from 1 PM Tuesday to 1 AM EST
Wednesday for NHZ001>006-009.
MARINE...Gale Watch from Tuesday evening through Wednesday morning for
ANZ150>154.
&&
$$
NEAR TERM UPDATE...Arnott
Area Forecast Discussion
National Weather Service Huntsville AL
857 PM CST Mon Feb 21 2022
.NEAR TERM...(Tonight)
Issued at 857 PM CST Mon Feb 21 2022
Afternoon rain and thunderstorms have pushed northeast to locations
mainly north of the Tennessee River early this evening. Scattered
thunderstorms producing some heavier downpours have continued to
develop this evening near and west of the I-65 corridor. Expect this
activity to continue to move northward as low/mid level drier/warmer
air moves into the region. Likely showers and a few thunderstorms
were kept in the forecast through 10 PM. Further southwest, rain has
mainly ended, but cannot rule out isolated to widely scattered
showers or storms through midnight.
This rainfall has helped keep us in the more stable airmass with
some wedging working in from the east. Temperatures have dropped into
the lower 50s in most locations. A few dewpoints have dropped into
the upper 40s in northeastern Alabama. Despite winds, additional
rainfall in northeastern Alabama through midnight will likely allow
temperatures to drop to dewpoint values in those areas. Thus, have
lowered low temperatures a tad into the upper 40s to lower 50s. These
lows should happen between now and midnight. Then warm air advection
and drier air in the lower/mid levels of the atmosphere from the
south will continue advecting into the region overnight. This should
allow temperatures to warm towards daybreak on Tuesday into the
lower to upper 50s. Winds should remain between 5 and 10 mph with
gusts at times to around 20 mph. These winds and continued cloud
cover should keep fog from developing tonight.
.SHORT TERM...(Tuesday through Wednesday)
Issued at 218 PM CST Mon Feb 21 2022
Tomorrow will be a tricky forecast, with a decent chance for severe
weather. Lets start with the overall pattern. As we go into Tuesday,
we have a deepening low-pressure center located over central Missouri
associated with shortwave activity in the southwesterly flow out
ahead of the deep stationary upper-level trough over the western
CONUS. As this low pressure circulation tracks northeast toward the
Great Lakes and the Northeast, it brings a fairly dynamic cold front
across the Tennessee Valley Tuesday night.
Shear out ahead of this front will be substantial, with 0-3 km SRH
values in excess of 400 m2/s2. Model soundings show a curved
hodograph supportive of rotating updrafts which would organize storms
into supercellular structures. The primary concern, again, will be
whether we will have enough instability. This is the part that gets
interesting/tricky. With cloud cover through the day tomorrow, you`d
think we won`t be able to destabilize very well, and a lot of the
time that is true. However, with temperatures warming via southerly
winds advecting in more warm, moist air, we`ll be not only starting
the day around 60 degrees in the morning, but we will likely warm
above 70 degrees by the afternoon. The national blend of models shows
that 75% of the model solutions have the temperature at Huntsville
getting above 72 degrees tomorrow afternoon. Looking at model
soundings from both the global models, the NAM, and the HRRR. They
don`t show much instability, but they also have surface temperatures
down around 66-68 degrees. If you warm the surface temperature up to
around 73-75 degrees, that erodes away much of the cap leaving
more instability to work with. Looking at the HRRR which, since 00Z
last night at least, has been showing supercellular structures in the
model reflectivity, this would certainly support a chance for strong
to severe thunderstorms, especially west of I-65 where temperatures
in NW Alabama could get up near 75. These occur out ahead of the cold
front and will need to be watched. Models have them developing around
2-3 PM.
As the afternoon progresses into the evening hours, these cells merge
into more of a linear feature and hang up along the storm-relative
flow which will be perpendicular to the line. This will allow for
convection along the front to catch up to this feature leading to two
lines of fairly heavy rainfall merging right across our entire area.
This is where we have our significant potential for flooding/flash
flooding overnight tomorrow night. The front slows down as it hangs
up on the storm-relative flow as well, becoming nearly stationary
across our area, training heavy rainfall across the same areas for
hours. This will bring a widespread swath of 1-2.5 inches of rain,
with most of it falling between midnight and 6 AM Wednesday. Wouldn`t
be surprised if there were areas that saw more. As we go into
Wednesday morning, we get a break in the rain as the front finally
drops to our south for about 6-12 hours.
.LONG TERM...(Wednesday night through Sunday)
Issued at 218 PM CST Mon Feb 21 2022
An upper low pressure system over the Pacific NW and west of the
northern Rockies will move southward, continuing a general
troughing pattern over the greater CONUS. This troughing should be
extending S-SW from upper lows over NE Canada and the Davis Strait,
being somewhat held up by strong upper ridging over the eastern Gulf
region. Another strong upper disturbance now south of SE Siberia will
move in the northern stream and help push the trough east of the
region during the weekend. The deterministic models were in rather
good agreement with big picture system positions early next week, all
showing troughing moving off of the eastern seaboard.
At the surface, a storm system now over the eastern Great Plains, by
late Tuesday should be heading rapidly to the NE over the Great
Lakes. A frontal boundary extending south of this low will gradually
approach the Tennessee Valley. Strong and cold Canadian high pressure
moving to the SE from Alberta will help push the frontal boundary
across the Tennessee Valley on Wednesday. An aformentioned upper
disturbance in the polar jet will help develop another over the
Desert SW on Thursday. This system as it heads eastbound will bring
overrunning type showers and a few thunderstorms over the Valley
during the Thu to early Friday timeframe. Kept most of the thunder
over our western areas closer to that system. Some of the rain with
this system will be locally heavy late Wed to early Fri. Excessive
rainfall of another one to over three inches on top of an already
saturated ground will runoff and contribute to more areal flooding
issues. The heaviest rainfall with this system appears will remain to
our north and west, but will be very close. The Flood Watch we have
going now may need extending if this heavy rainfall looks more
likely. Overall storm strength overall should be on a weaker side
with the higher instability staying to our south and east.
The cold front should push across the area on Fri bringing an end to
the heavy rainfall. Much colder air filtering in behind the front
will bring a noticeable drop in temperatures to close out the work
week. After highs on Thu warming into the upper 60s and lower 70s,
despite clouds and showers, they will struggle into the upper 40s to
lower 50s on Fri and during the weekend.
With cold air in place, another upper system is forecast to move
across the area late Saturday into Sunday. With highs only near 50 on
Sun and falling below freezing that night, a mix of rain/snow looks
possible as we go into a new workweek. It`s way too far out to
contemplate accumulation. Think most ground surfaces should remain
free of snow accumulations, but cannot say the same for elevated
surfaces or grassy areas. Another shot of even colder air will end
the month of February on a chilly note with highs only in the mid 40s
and lows to start the month of March in the lower 20s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 527 PM CST Mon Feb 21 2022
MVFR to IFR CIGS/VSBYS and maybe some CB are expected at times
through 1Z, before a round of stronger TSRA are expected between 2Z
and 4Z at KMSL and between 3Z and 5Z at KHSV (IFR to MVFR CIGS/VSBYS
possible then), as a warm front moves through the terminals. Expect
easterly winds to become southerly after midnight remaining around 10
knots with gusts around 20 knots. Expect conditions to become
predominantly VFR after 6Z. Wind gusts should pick up a bit more
after 15Z on Tuesday with gusts up to 28 knots possible. Wind shear
around 40 knots is expected through 15Z. Another round of TSRA is
expected to affect the terminals after 21Z. For now only included
PROB30 group including TSRA and IFR CIGS being so far out in the
forecast after 21Z.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Flood Watch from Tuesday afternoon through Wednesday morning for
ALZ001>010-016.
TN...Flood Watch from Tuesday afternoon through Wednesday morning for
TNZ076-096-097.
&&
$$
NEAR TERM...KTW
SHORT TERM...McCoy
LONG TERM...RSB
AVIATION...KTW
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service New Orleans LA
932 PM CST Mon Feb 21 2022
...EVENING UPDATE...
Performed a small update to the near/short-term forecast to
reflect recent model guidance and obs trends. We are continuing to
see low clouds build in for just about all of the area, with
cloud bases ranging between 1000 to 2500ft AGL. Low clouds will
likely persist through the night and into daybreak Tuesday with an
overall moist PBL to low-level thermal profile in place. Right
above, we are starting to see the front edge of dry air advecting
in between 900 and 800mb from the western Gulf, with vertically
deeper, drier air expected to continue to build into the region
through early Tuesday, leading to increased
subsidence/compressional warming resulting in a strengthening low
to mid-level inversion. Meanwhile, a subtle mid-level impulse,
riding SW 500mb flow has already led to convection igniting across
the south-central Plains, with a weak surface low/trough
developing and expected to quickly eject northeast through early
Tuesday. With greater upper-level dynamics racing away from the
region (subtle height rises aloft), we never really see enough
large-scale dynamic ascent to offset the warm thermal layer
situated in the low to mid-levels regardless of building
temperatures/instability throughout the day. Something additional
to note: H5 to H7 lapse rates are relatively high, but this is
because of compressional warming in the upper portion of the
inversion per recent forecast soundings. 00Z HRRR guidance barely
has any convection in the CWA, and whatever forms across SW MS
struggles to attain enough vertical depth due to all the
aforementioned unfavorable conditions working against deep
convection. However, looking closer at the SFC to 925mb wind
profile over the area hints at just enough low-level directional
wind convergence from east to west across the area, allowing for
perhaps enough localized lift to lead to a few isolated bands or
"streets" of shallow showers maybe some storms, primarily north of
I-10/12 at times during the day. But overall, not anticipating
severe weather in our CWA with any mentionable threat primarily to
our north. But as always, will monitor especially across far
northern areas.
Did slightly adjust highs for Tuesday to account for the warmer
bias we saw today underneath strong return flow. Aiming closer to
the 75th percentile in the ensemble spread placing many areas in
the 80s to perhaps some mid 80`s in a few places with no other
adjustments required elsewhere. KLG
&&
AVIATION (00Z TAF DISCUSSION)...
Primarily VFR to a few mixed MVFR CIGS persist this evening with
low to mid-level clouds in place. Forecast calls for low clouds to
build in yet again later this evening into tonight, with a
majority prevailing MVFR to periodic IFR expected into daybreak
tomorrow. Can`t rule out a patchy isolated area of light showers
or drizzle primarily after 03Z thru 14Z in a rich, moist return
flow airmass in place. Otherwise, surface winds will remain
relatively elevated all night at around 07-14kt sustained bearing
150 to 170 into the day on Tuesday, with patchy clouds and
VFR/MVFR CIGs expected thru Tuesday afternoon/evening. KLG
PREV DISCUSSION... /issued 345 PM CST Mon Feb 21 2022/
SHORT TERM (TONIGHT THROUGH THURSDAY)...The forecast area will
remain embedded beneath a persistent southwesterly flow pattern in
the mid to upper levels through Thursday night. Embedded within
this southwest flow, two fast moving shortwave troughs will pass
through the Plains and into the Midwest. Only the trailing end of
these troughs is expected to pass directly over the area, but
upper level forcing should sufficient to bring an increased chance
of rain to the area during the day tomorrow. Fortunately, the risk
of severe thunderstorms has diminished due to the further north
track of the upper level system. Shear values are not anticipated
to be as high as previously thought, and this should help to keep
any thunderstorms that form tomorrow below severe limits. At most,
a very isolated strong to severe thunderstorm could form over
parts of Southwest Mississippi where shear values will be
greatest tomorrow afternoon. The deep layer southerly flow pattern
will continue to usher very warm into the area, and highs should
climb into the upper 70s and lower 80s during the afternoon hours.
This warm and humid airmass will be passing over cooler nearshore
waters, and a weakening of the wind field tomorrow night to around
10 knots will be very supportive of a decent sea fog event
forming by the evening hours. This dense sea fog should spread
inland through the night, and the forecast calls for fog across
most of the forecast area by daybreak on Wednesday. This fog may
then linger over the coastal waters through the entire day on
Wednesday, but should clear over land areas by the afternoon.
Skies should turn partly cloudy by the afternoon hours as some
drier air in the mid-levels associated with a weak shortwave ridge
axis and increased upper level subsidence mixes down to the
surface. This slight increase in solar insolation and the weak
subsidence aloft should also allow temperatures to climb into the
lower to middle 80s or near record high levels by Wednesday
afternoon. There may be a few widely scattered showers and
possibly an isolated weak thunderstorm that forms over the
northern third of the CWA Wednesday afternoon, but slightly weaker
mid-level lapse rates will limit overall convective potential
through the day.
Another round of dense advection fog will impact the area
Wednesday night into Thursday morning. This fog will linger
through the late morning hours, but should begin to lift as the
second shortwave trough axis begins to approach the region from
the west. As mentioned earlier, the main core of this upper level
trough will pass well north of the region, but this will also be a
much deeper system. As a result of this deepening, a low pressure
system and related cold front will form over the Plains Wednesday
into Thursday. As the parent trough begins to pull into the
Midwest, the surface low and front will also quickly track to the
east. This front is expected to pass through the forecast area
Thursday night into Friday morning, and a band of rain should
accompany it`s passage. Mid-level lapse rates will remain weak, so
the risk of thunderstorm activity will be low to non-existent as
this front moves through. In fact, the majority of the rain will
develop in the wake of the front on Thursday night, as cooler air
near the surface is overrun by the continued warmer and more
humid southwesterly flow regime in the mid to upper levels.
Temperatures will remain very warm, and some compressional heating
in advance of the front could push temperatures into the mid 80s
and into record high territory at several locations Thursday
afternoon. Temperatures should begin to cool quickly after frontal
passage, and readings are expected to be in the 40s and 50s by
daybreak on Friday.
LONG TERM (FRIDAY THROUGH MONDAY)...Model spread has lessened,
and forecast confidence has increased for the upcoming main Mardi
Gras weekend. The southwesterly flow pattern in the mid and upper
levels will continue through Saturday, and this will keep skies
overcast for both Friday and Saturday as the warmer and humid air
is isentropically forced over a shallow cold pool near the
surface. Fortunately, strong subsidence and negative vorticity
advection above an elevated temperature inversion associated with
a 925mb thermal trough axis sliding through the region will
reduce rain chances to near zero from Friday evening through
Saturday evening. This drying out is most evident in the low
precipitable water values of around half an inch currently
forecast by medium range guidance. The thermal trough axis and the
overcast skies will make for a very chilly couple of days. Highs
should only warm into the upper 50s and lower to middle 60s each
day and overnight lows should dip into the 40s.
The timing of the next shortwave trough axis has come into better
agreement, and most ensemble members are pointing to a passage of
this trough and cold front on Sunday. Little in the way of low
level moisture return is expected as winds remain largely offshore
in advance of this system, but enough mid-level moisture should
feed into the region to allow for at least chance PoP during the
day on Sunday. A lack of instability will keep the risk of
thunderstorms suppressed, but another post-frontal rain band could
pass through the region on Sunday. The rain should be very short-
lived as the flow pattern aloft turns northwesterly in response to
the southern stream trough phasing with a northern stream system
moving into the Great Lakes by Sunday night. This deep layer
northwest flow pattern will lead to rapidly clearing skies Sunday
night into Monday and much colder air advecting into the region.
Overnight lows should fall into the 30s and lower 40s Sunday night
and similar conditions are expected for Monday night. Highs on
Monday will struggle to reach the upper 50s as a very cold airmass
moves in from the north.
MARINE...The pressure gradient has tightened considerably today
in advance of an approaching low pressure system, and this has
resulted in southerly winds of 15 to 20 knots taking hold over
most of the coastal waters. These winds should persist into
tomorrow before easing tomorrow night as the gradient over water
relaxes slightly. However, this easing of the wind field will make
the formation of dense fog more likely. This dense sea fog will
likely form during the evening hours tomorrow and then potentially
persist through Thursday morning before lifting. It will take the
passage of a strong cold front Thursday afternoon into Thursday
night to fully clear the fog, but a return to small craft advisory
conditions is expected after the front moves through. These
stronger winds of 20 to 25 knots and seas of 4 to 7 feet will
develop by Friday morning and continue through Saturday.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 65 85 65 81 / 10 50 20 40
BTR 66 84 66 82 / 10 40 10 30
ASD 63 83 63 78 / 10 30 10 20
MSY 66 83 66 78 / 10 30 10 10
GPT 62 76 62 73 / 10 20 10 10
PQL 61 79 62 76 / 10 20 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory from 3 AM to noon CST Tuesday for GMZ550-
552-570-572.
MS...None.
GM...Small Craft Advisory from 3 AM to noon CST Tuesday for GMZ552-
570-572.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
946 PM EST Mon Feb 21 2022
.UPDATE...
Issued at 946 PM EST MON FEB 21 2022
Long-duration winter storm continues this evening for areas along
and north of M-28 west of Marquette associated with a band of fgen
at 700 mb. In addition, NE wind upslope off Lake Superior is keeping
lake effect snow bands/showers going into the northern half of
Marquette County on the southern edge of the synoptically-forced
snow.
The concern is tomorrow afternoon with the well-advertised second
wave of this storm. 21z RAP and 00z HRRR show impressive 6-hour QPF
amounts of 0.35-0.5" in the 18z-00z time frame generally along and
northwest of a line from Iron Mountain to Munising. Further
complicating things is the banded precip signal in QPF fields from
both of these models which may lead to snow amounts varying
considerably over short distances. The other complicating factor is
the thermals. Although this has been advertised as a light and
fluffy snow, in reality the warm nose moving in as the 850 mb low
tracks from Menominee to Manistique will lead to warming outside of
the DGZ and thus lower SLRs, as well as perhaps some sleet south-
central and east. Will note that the 00z NAM is right on the money
with the 850 mb temp at MPX vs the 00z sounding, whereas the 00z RAP
is about 2 C too cold.
There will be a period of heavier snow rates with lower SLRs leading
up to and during the evening rush hour tomorrow. These additional
amounts, plus what`s already fallen, could justify an upgrade to a
Winter Storm Warning for the western half of the CWA. However, have
decided to hold off since it would be confusing to upgrade now only
to have people wake up and see little to nothing happening in the
morning. However, an upgrade may be needed with the morning package
if the CAMs do not stray from their current solutions. That said,
did incorporate some of the aforementioned wetter guidance to boost
snow amounts tomorrow afternoon by about 1-2" over the previous
forecast over the western half of the CWA.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 156 PM EST MON FEB 21 2022
System snow is starting to move in this morning and on the radar,
can see lake effect snow moving southwest near Marquette County as
well and system snow moving east. Sharp cutoff to the pcpn exists
from Iron Mountain to just north of Escanaba and Manistique and look
for that to continue this afternoon. Can definitely see the Lake
Superior influence in banding in the snow in Marquette County.
Overall, the forecast still looks good and no updates planned.
.LONG TERM...(Tuesday night through Monday)
Issued at 344 PM EST MON FEB 21 2022
Overall thinking of the evolutions of the weather systems during the
first 36 hours of the forecast beginning tonight has not changed a
lot...just some subtle changes. Frontogenesis axis has been setup
mainly along and north of the M28 corridor from Ironwood to
Marquette. Most areas in this zone will have seen 2-5 inches of snow
by early this evening with the highest totals in northeast winds
upslope areas with several narrow bands of lake effect streaming in
from the northeast. FGEN forcing wanes overnight with main snow
forcing transitioning to mainly light lake enhanced/upsloping. Snow
amounts from midnight tonight through mid-morning Tuesday will be in
the 1-3 inch range. Have lowered snow total a little for the
overnight and Tuesday morning time period mainly due to lower SLR`s.
Our SLR`s thus far have been running around 12:1...a little lower
than would have thought. With warm nose increasing around 80H
overnight into Tuesday...will lose deeper DGZ and thus do not think
SLR`s will get any higher than current.
Main surface wave moves from northern IL into lower Michigan
tomorrow. Deformation precip area will move across the U.P. during
the afternoon and early evening with the next round of moderate
precipitation. Northeast wind upslope and enhancement will continue
so highest snow total will continue to be in the highlands of
Marquette/Baraga counties and near the Porkies. Biggest question and
challenge of the whole snow forecast is along the US2 corridor from
Delta county into the eastern U.P. There could be a little sleet
that mixes in this area with 80H warm nose surpassing freezing. Snow
amounts have been lowered in this area to more in the 3-5 inch
range...mainly Tuesday afternoon/evening. However, this remains the
zone of least confidence and amounts could trend back slightly
higher.
No changes are planned to ongoing headlines. With only minor amounts
of snow expected across the south and east through midday Tuesday
won`t add any additional advisories at this time. Will keep the
advisory across the west mentioning the overnight lull in snow
before increasing again tomorrow afternoon.
Weather becomes much quieter after any lingering lake effect dies
down on Wednesday. A system may move through the lower lakes Friday
grazing southern areas and another clipper over the weekend could
increase lake effect briefly on Sunday...but no major storms are
expected any time soon beyond this one.
Other than Saturday when temperatures will be close to normal,
temperatures will remain below normal into early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 633 PM EST MON FEB 21 2022
LIFR vis continues at IWD and CMX for the next few hours before the
first wave of snow pulls out to the northeast late this evening. SAW
remains on the southern edge of this wave of snow, but is also
dealing with NE wind upslope/lake effect snow showers embedded
within the wave of snow. Late tonight, all terminals should go IFR
with much lighter snow between waves. CMX and IWD may even see a
brief period of MVFR vis early tomorrow morning. All terminals will
then drop back into LIFR by late morning or early afternoon Tuesday
as the second wave of snow moves in from the southwest.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 344 PM EST MON FEB 21 2022
Northeast gales to 40 knots will continue through Tuesday night
before diminishing. Heavy freezing spray will continue through
Wednesday. Winds will be light Thursday and Friday...mainly below 20
kts. Next clipper moves in over the weekend with the potential for
southwesterly gales ahead of it followed by gusty northwest winds
late in the weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 7 AM EST /6 AM CST/ Wednesday for
MIZ001>005-009-010-084.
Lake Superior...
Heavy Freezing Spray Warning until 7 PM EST Wednesday for LSZ243-
244-263-264-266-267.
Gale Warning from 1 PM Tuesday to 7 AM EST Wednesday for
LSZ249>251-266-267.
Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Wednesday
for LSZ162.
Gale Warning until 7 PM EST /6 PM CST/ Tuesday for LSZ162.
Gale Warning from 7 AM Tuesday to 7 AM EST Wednesday for LSZ243-
244-264.
Gale Warning until 7 AM EST /6 AM CST/ Wednesday for LSZ240>242-
263.
Lake Michigan...
None.
&&
$$
UPDATE...RJC
SHORT TERM...07
LONG TERM...MZ
AVIATION...RJC
MARINE...MZ
AREA FORECAST DISCUSSION
National Weather Service Morristown TN
933 PM EST Mon Feb 21 2022
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
Radar shows showers moving in from the southwest. No lightning yet
over our area, but there are a few flashes off to our west and
southwest and a few rumbles cannot be ruled out overnight
especially south/west although convective energy will be very
limited. Current forecast generally looks to have a decent
handle on the precipitation. Biggest change with this update will
be to lower min temps across nearly all of the area as current
temperatures are approaching the forecast lows in many locations.
The cloud cover and wind will not allow temps to drop too much
more, but will make some adjustments. Will also tweak sky cover
and dew points with this update. Will leave the Tuesday high wind
warning in the mountains as is for now, and no changes to the
flood watch for Tuesday night.
&&
.AVIATION...
00Z TAF DISCUSSION.
Will see an area of showers move across the area from southwest to
northeast tonight. CHA will be MVFR for much of the period before
some improvement to VFR late, and may dip to IFR in a heavier
shower early. TYS/TRI look likely to stay mainly VFR, but will
try to time better chance for showers with tempo groups including
MVFR vsby and cigs later tonight. Other concern will be possible
LLWS. The strongest probability for LLWS looks to be at CHA so
will include for several hours there later tonight/early Tuesday.
LLWS looks borderline at TYS/TRI later tonight so will leave out
for now. Winds will be gusty from the southwest Tue afternoon.
&&
.PREV DISCUSSION...
/ISSUED 255 PM EST Mon Feb 21 2022/
SHORT TERM...(Today through Tomorrow)
Key Messages:
1. Initial round of showers moves into the forecast area tonight,
marking the beginning of a wet week ahead.
2. High Wind Warning issued for the southern Appalachian Mountains
tomorrow.
Discussion:
Initial round of rain showers with a few embedded weak thunderstorms
is moving across the Tennessee Valley this afternoon. It`s
continuing to weaken as it moves further east away from the better
isentropic lift, but it is remaining somewhat stronger and more
organized than most CAMs and guidance suggested. Have bumped up PoP
chances and QPF amounts a bit along the southern TN border to account
for these radar trends. Surface obs and radar estimated
precipitation totals generally paint most locations as seeing around
0.10" or less per hour associated with this round of rain. Expect
the majority of it to remain south of the TN border as it moves
eastward, but southeast TN into southwest NC will likely pick up
measurable precipitation with it.
Isolated weak showers will likely remain in the area this evening
into the overnight hours as the front makes it`s way closer to the
area. Minimal precipitation is expected from these weak showers
however. But the increased cloud coverage, and more southerly wind
will keep overnight temperatures pretty warm, with most locations in
the Valley expected to remain in the upper 40`s or low 50`s for a
minimum temperature.
Tomorrow during the daytime expect the precipitation to mostly be
out of our area, sticking to the north and west closer to the better
synoptic forcing. Likely the most notable weather during the daytime
hours tomorrow will be the breezy southerly to southwesterly winds
as the low level jet moves into the region. This 50+ knot jet will
cause the biggest impacts in the southern Appalachian Mountains
during the daytime tomorrow. There looks to be enough of a southerly
component to the winds that we`ll experience some weaker mountain
wave effects with this jet. But with a 50+ knot jet regardless of
the direction it`s going to be very breezy in the higher elevations
along the Appalachians. Will upgrade the High Wind Watch to a High
Wind Warning for tomorrow. Elsewhere most people will notice the
very warm temperatures and breezy conditions associated with this
jet as most people in the Valley should see temperatures climb above
70 tomorrow.
ABM
LONG TERM...(Tuesday night through Monday)...
Key Messages:
1. Excessive rainfall will be the main concern on Tuesday night and
again on Thursday/Friday.
2. Strong winds expected expected across the higher elevations
Tuesday night and again on Thursday night.
3. Cooler airmass and a southern track system could bring some mixed
precip to the Southern Appalachians on Sunday but uncertainty is
high.
Discussion:
A cold front will begin to stall as it moves southeastward across
the Tennessee Valley on Tuesday evening into the overnight hours.
Convection will be occurring along and ahead of this front. A jet
streak across the Ohio Valley will place us within the right
entrance region for upper divergence as well as diffluent flow aloft.
RAP model guidance suggests PW values around 1.6 inches which is
near the max of climatology. In addition, MLCAPE of 100 to 200 J/Kg
and MUCAPE of 300 to 500 J/Kg will limit severe convective
potential. This skinny CAPE profile and high moisture will be
supportive of convective updrafts supportive of heavy rainfall, and
this is further supported by saturated forecast soundings and deep
warm cloud layers. With storm layer flow parallel to the front, some
training convection will be possible. With potential training and a
favorable setup for heavy rainfall rates, conditions will be
favorable for locally heavy rainfall. For this reason, will issue a
Flood Watch to match up with neighbors that is focused on locations
for potential heaviest rainfall rates. Overall QPF totals are
expected to be one to two inches, but locally higher amounts of
three to four inches will be possible with any training cells.
The front is forecast to be south of the forecast area on Wednesday
with dry conditions across our zones. Southerly flow will bring this
front northward Wednesday night and Thursday with increasing clouds
and precip across the region once again. As the cold front moves
across the area on Thursday night, additional rounds of locally
heavy rainfall will be possible as PW values near 1.6 inch will be
around the max of climatology. Forecast soundings show the saturated
airmass and a relatively deep warm cloud layer depth for this time
of year. Most of this week is forecast to be above normal for
temperatures with the warm southerly flow and ridging across the
Southeast CONUS.
Northerly flow will bring drier air late Friday through Saturday as
high pressure builds in from the northwest as temperature dip back
below normal. A shortwave moving eastward across the Southern Great
Plains is forecast to initiate cyclogenesis across the northern Gulf
Coast on Saturday night or Sunday with the potential for mixed
precip spreading northward across the Southern Appalachians. Any
frozen precip would be most probable across the higher elevations.
With this being a Day 6 system, confidence is low in any direct
impacts or precip amounts.
JB
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 51 72 60 70 55 / 60 40 90 60 50
Knoxville McGhee Tyson Airport, TN 50 73 58 66 51 / 60 40 90 60 60
Oak Ridge, TN 50 72 57 67 49 / 70 50 100 50 70
Tri Cities Airport, TN 46 71 56 65 49 / 60 40 90 60 70
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Flood Watch from Tuesday evening through Wednesday morning for
Anderson-Bledsoe-Blount Smoky Mountains-Bradley-Campbell-
East Polk-Hamilton-Knox-Loudon-Marion-McMinn-Meigs-Morgan-
Northwest Blount-Northwest Monroe-Rhea-Roane-Scott TN-
Sequatchie-Southeast Monroe-West Polk.
High Wind Warning from 7 AM to 7 PM EST Tuesday for Blount Smoky
Mountains-Cocke Smoky Mountains-Sevier Smoky Mountains.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service Pendleton OR
745 PM PST Mon Feb 21 2022
.UPDATE...An upper level low pressure system slowly moving through
the region was continuing to produce light snow across the area.
The latest web cams was showing heavy snow over portions of the
blue mountains and thus the wsw had been extended into the night
for this area. Meanwhile the nbm continued to show accumulating
snow over central Oregon eastward although this decreases somewhat
towards seneca. Otherwise another band of light snow is
continuing to strike the southern blue mtns and all the winter
weather advisories have also been extended into the night. Colder
air on nne winds may also create some upslope that may also add
to some of the accumulation and persistence. The probabilistic
graphic generator was indicating tonights low temps dropping into
the single digits across portions of central Oregon and the area
mountains and between 10 to 15 in the basin. Even colder temps are
expected Wednesday morning.
Otherwise changes had been done to
pops...sky...weather...temps...qpf...snow amts...winds...and now
the short term forecast appears even more on track.
&&
.PREV DISCUSSION... /issued 255 PM PST Mon Feb 21 2022/
SHORT TERM...Tonight through Wednesday Night...A large and deep
upper trough continues to move south over the forecast area this
afternoon. Clouds show some convective nature and snow, rain and
even some some graupel showers have been happening this afternoon
and will continue this evening before tapering off late tonight and
tomorrow morning. The showers have been a little slower to develop
and the HRRR continues them longer than earlier runs, so will be
extending current Winter Weather Advisories and Warnings through 7
PM this evening. An exception will be the Winter Weather Advisory
along the East Slopes of the Oregon Cascades which will continue
through 10 PM this evening. The Southern Blue Mountains, Ochoco-
John Day Highlands, the East Slopes of the Oregon Cascades will
get another 2 to 5 inches of snow with 1 to 3 inches in the
Northern Blue Mountains and Central Oregon.
An Arctic Cold Front is now moving into the area and winds are
turning northerly and increasing to 10 to 20 mph already in the
Yakima and Kittitas Valley and in the Lower Columbia Basin north of
the Tri-Cities. Expect that the breezy to windy conditions will
continue from now until tomorrow evening over most of the area. At
the same time, as anticipated, temperatures are already falling
and a very cold period will be with us for the next few days.
Temperatures approaching record lows will be possible tonight but
even more so Tuesday night as temperatures get even colder.
Temperatures tonight will be in the teens in the Columbia Basin
and 2 to 12 above in the mountains and central Oregon. Tomorrow
night the Columbia Basin will be 5 to 15 above with 5 below to 5
above zero elsewhere. Daytime temperatures Tuesday and Wednesday
will be in the 20s and lower 30s with 10 to 20 in the mountains.
One additional concern will be the cold temperatures and windy
conditions developing very cold wind chills. Tonight through
Wednesday will see wind chills below zero in many locations with
values at times reaching 10 to 15 below zero. At this time, it
does not appear that wind chills will reach the criteria for a
Wind Chill Warning but this will have to be monitored over the
next couple of days.
By Wednesday night, the trough will shift a little eastward and
an offshore ridge will begin to influence our area. This will
begin to moderate the temperatures with the lower elevations
warming a few degrees to the mid teens to lower 20s while the
mountains and central Oregon will warm to zero to 10 above. Winds
will be lighter Wednesday and Wednesday night and no precipitation
is expected Tuesday night through Wednesday night. Perry/83
LONG TERM...Thursday through Monday...The long term is
characterized by a warming trend that is expected beginning on
Thursday that will bring our region to near seasonal temperatures
through the end of the week and into the weekend, with a weak
system on Thursday possibly bringing light mountain snowfall, with
a more impactful system late in the weekend.
Models are having trouble to start the forecast period with a weak
trough diving across the borders of WA/OR/ID. This continental
based upper level system is expected to be fairly dry, but the
ECMWF and its ensembles shows a notable band of precipitation out
of this feature, while the GFS/GEFS remains drier with perhaps a
very quick shot of light mountain snowfall for the eastern
mountains of our region. Ensemble analysis isn`t easy, but based
on 500mb height anomalies and the cluster phase space diagram,
there is better agreement with the ECMWF and its ensembles vs the
GFS. Therefore, although the NBM remained quite dry for this run,
elected to at least produce a signal of precipitation for the
Blues and Wallowas, but it does remain very light, and confidence
in this precipitation is low (20-30%).
After this feature departs into Friday, high pressure ridging
takes hold and remains the dominant weather feature through
Saturday evening. Temperatures continue to rebound all weekend,
with highs in the upper 40`s by Sunday and 50`s by Monday for the
lower elevations. A deeper, marine based upper level trough is
expected to begin overspreading the region late Saturday into
Sunday, with a wetter pattern expected to end the weekend and
begin next week. Precipitation amounts look light, with continued
warming raising snow levels through the end of the forecast
period. Goatley/87
AVIATION...00Z TAFs...Mostly VFR to MVFR conditions continue.
Periods of IFR remain possible as ceilings drop locally and
visibilities reduce due to nearby snow. Precipitation expected
most sites through 06Z, with lingering snowfall through 09Z for
BDN/RDM. Breezy northerlies expected overnight, continuing into
Tuesday and overspreading most sites except DLS. Strongest winds
YKM/PSC with gusts 20-30kts. Goatley/87
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 14 27 8 26 / 40 0 0 0
ALW 18 30 10 28 / 30 0 0 0
PSC 19 33 15 32 / 20 0 0 0
YKM 14 29 8 31 / 20 0 0 0
HRI 17 31 12 30 / 20 0 0 0
ELN 12 25 7 27 / 10 0 0 0
RDM 8 24 -3 27 / 60 10 0 0
LGD 12 22 4 21 / 40 10 0 0
GCD 13 26 2 26 / 50 10 0 0
DLS 21 32 15 33 / 40 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 4 AM PST Tuesday for ORZ503-506-
509.
Winter Storm Warning until 4 AM PST Tuesday for ORZ502.
WA...Winter Storm Warning until 4 AM PST Tuesday for WAZ030.
&&
$$
SHORT TERM...97
LONG TERM....87
AVIATION...87
Area Forecast Discussion
National Weather Service Topeka KS
834 PM CST Mon Feb 21 2022
.UPDATE...
Issued at 834 PM CST Mon Feb 21 2022
The cold front has been much faster moving into the forecast area
this evening and the 00Z models are still trying to catch up with
the magnitude of the cold air advection. Have noticed a lot of
surface obs across south central NEB have been reporting light
snow. And GID pointed out the RAOB from LBF showing the cold air
much deeper with the stratus cloud in the dendritic growth zone a
few thousand feet off the ground. Even the OAX RAOB has the base
of the stratus layer near -10C. This may diminish the chances for
freezing drizzle overnight if the stratus layer is colder then
the models prog allowing for more flurries than drizzle. Have
trended the forecast in this direction but am hesitant to pull
freezing drizzle completely out of the forecast.
The faster progression of the cold front does seem to limit the
chances for thunder this evening across east central KS. 01Z RAP
forecast soundings suggests what ever instability there will be is
over east central KS now. With the cold air moving through faster
and convection still down along the Red River, have removed the
chance for showers and thunderstorms across east central KS.
Saturation and lift in the low levels appears to be more limited
across this area as well, so I don`t bring the snow or freezing
drizzle this far south.
Have also bumped up wind speeds across the entire area with models
showing a good pressure gradient through the night. Even with the
stronger winds and quicker drop in temps, wind chill values look
to remain above -15F over north central KS. So I don`t plan to add
any counties to the wind chill advisory at this time.
&&
.DISCUSSION...
Issued at 248 PM CST Mon Feb 21 2022
At 20Z today, a strong cold front bisected the CWA creating a large
temperature gradient from northwest to southeast across the area.
Temperatures were falling quickly behind the front. At KCNK
(Concordia) temperatures dropped 10 degrees between 19Z to 20Z
and were in the low 40s at 20Z. Meanwhile at KMHK (Manhattan),
temperatures were at 70 degrees at 20Z. Ahead of the front this
afternoon, elevated fire danger conditions will remain in place
given low RH values and breezy winds. A few storms could develop
along the boundary by about 02Z (8 PM) near or just north of I-35
where about 200-400 J/kg of CAPE could build. As the colder air
mass overspreads the area, soundings show a saturated layer a few
thousand feet deep in the low levels (under 5,000 ft AGL). As lift
increases through the layer, drizzle could develop with a
possible limiting factor being a layer of drier air in the lowest
1,000 feet. If drizzle can overcome the drier air for a few hours,
a few slick spots could develop by early morning since
temperatures will be below freezing in most spots. The best chance
for the drizzle will be across northern and eastern portions of
the CWA.
In stark contrast to temperatures today, highs tomorrow will only
range from around 20 degrees in northern KS to near 30 degrees in
east-central KS (a good 40 to 50 degree difference in 24 hours).
Cold weather will be here to stay for the rest of the week. Wind
chills by Wednesday morning are forecast to drop to between -10 and
-15 degrees, which could warrant an advisory for counties in far
northern KS.
Another mid level system will move over the area on Thursday. Some
good lift should be realized early as the area becomes positioned
under the left exit region of a 100 knot jet. Models, however, are
showing dry air at 500 mb. Thus, light precipitation is expected at
this time, most of which should fall as snow. At this point, we are
forecasting minor accumulations of less than a inch before the
better dynamics move east of the area. Cold air becomes reinforces
as a surface ridge builds in late this week and early next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday)
Issued at 458 PM CST Mon Feb 21 2022
The cold front is moving through a little sooner than expected.
Think this probably keeps the TS chances southeast of FOE. There
is good agreement in MVFR stratus moving in behind the front.
Forecast soundings continue to show some vertical motion within
the cloud. However RAP isentropic surfaces are not as obvious
with the lift implying any -FZDZ could be pretty temporary. Of all
the guidance, the NAM is the only one generating light QPF. So
confidence in the drizzle forming is to marginal to include in the
forecast at this time.
&&
.FIRE WEATHER...
Issued at 248 PM CST Mon Feb 21 2022
Very high fire danger will continue through this afternoon ahead
of a cold front where temperatures have warmed to near 70 degrees.
Minimum RH values are between 20 and 30 percent for with winds
between 10 and 20 mph. Winds are abruptly shifting from the
southwest to the north behind the front and will continue to be
breezy through the night.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Wolters
DISCUSSION...Teefey
AVIATION...Wolters
FIRE WEATHER...Teefey
Area Forecast Discussion
National Weather Service Las Vegas NV
804 PM PST Mon Feb 21 2022
.SYNOPSIS...A strong storm system has begun to impact the region
today by way of strong winds, blowing dust, and convective snows
today with more opportunities for winter weather impacts through
Wednesday, especially for Lincoln and Mohave counties as well as
Morongo Basin. Conditions improve late week with gradual warming
but breezy northerly winds heading into the weekend, especially
for the Colorado River Valley.
&&
.UPDATE...Round 1 of the winds is coming to an end as observations
across much of the region show gusts diminishing below 40 mph. So,
the wind advisory was allowed to expire. The exception tonight will
be the western Mojave Desert and eastern Sierra slopes of Inyo
County where higher gusts will likely continue.
As the cold upper low over the Pacific Northwest sags south tomorrow
models show Round 2, a belt of strong southwest winds develops
across the western Mojave Desert extending northeast into southern
Nevada. With this update will go ahead and issue a wind advisory for
parts of southern Nevada and San Bernardino County. The advisory
will run from 10 am PST through 8 pm PST.
&&
.SHORT TERM...Today through Wednesday.
A rather complex next 48 hours is expected across the region as a
strong winter storm system swings across the southwest,
drastically lowering snow levels and tapping into some Pacific
moisture as it does.
WIND EXPECTATIONS: Already today, impressive downslope winds have
been reported over the eastern Sierra per RAWS sites...as high as
80 mph. While this has mostly stayed confined to the Sierra and
not yet resulting in reaching HWY 395, we opted for an upgrade to
a High Wind Warning for that zone, maintaining wind advisory for
the Owens Valley. This was well reflected with the 12Z HRRR wind
fields. Farther east, a strong corridor of southwest winds has
developed from San Bernardino to northern Arizona. This has
resulted in peak wind gusts over 60 mph for places like KIGM and
resultant dust storms in Mohave County where a DSW was issued. All
of these impacts are due to the passage of a shortwave to the
east that will be further reinforced with much colder air behind
it on Wednesday.
As such, winds will continue to be a concern for tomorrow but
perhaps to a slightly lesser degree as surface gradients maintain
their southwest to northeast orientation but are more localized to
the second pre-frontal low centered over southern Nevada. This
could tighten the gradient in some places, but loosen it in
others. A blend of hi-res solutions currently show max gusts
tomorrow generally below Wind Advisory criteria but this may
change by tonight.
WINTER WEATHER EXPECTATIONS: As previously mentioned, the second
round of energy from this low will be much colder and swing widely
across southern California tomorrow night, enough to shift upper
level winds southwesterly just before the trough axis and its
strong vorticity advection slams into the mountains in San
Bernardino. This will work to advect in moisture, tanking snow
levels, and put Lincoln County and Mohave into a favorable RER
regime of the low.
What does this mean for...
Morongo Basin: It means there will be a period of heavy snowfall
for Big Bear overnight Tuesday into Wednesday morning where
Winter Storm Warnings are in effect from SGX. With the very strong
winds aloft, there is a chance this heavy snowfall will blow over
into Morongo Valley and perhaps Yucca Valley, especially in the
foothills and elevations above 3000ft. At this moment,
deterministic values are quite low, but this is a point of high
uncertainty in the forecast as probabilistic values range from
trace to over 4 inches for the Morongo/Yucca Valley floors. While
uncertainty is high, there are too many reasons why the higher end
of the probabilistic envelope is plausible and if so, would
result in accumulating snows for Yucca and Morongo. As this is all
happening while snow levels are rapidly decreasing, feel a head`s
up on the potential for hazardous travel is prudent.
Lincoln County: Accumulating snowfall county wide, but greatest
concern being HWY 93 from Caliente and north. This will be where
the coldest temperatures will occur, being directly underneath the
low center, but also lacking the best moisture. As the low
progresses, this will put the eastern half of the county in a
favorable dynamical set up for lift to tap into the moisture
available and also include meager but non-zero convective
potential with the low center. Latest projections did bump these
values down with a more easterly, progressive track of the low
though, so opted to cover this with a Winter Weather Advisory.
Mohave County: Accumulating snowfall for the eastern 2/3 of the
county. For all the same reason Lincoln is expected to receive
snowfall, Mohave will have an even better position both
dynamically and convectively relative to the parent low. Again,
latest projections in the HREF and NBM have backed off some with
respect to QPF, but the potential for convective banding within
the RER of the low is rather good and if so, would result in
locally higher amounts than those currently forecast (1-3 below
3000ft and 4-8" above). Strongest signal for this is the Arizona
Strip including Colorado City and the Kaibab Indian Reservation
(north of SR 389) so the higher end of those estimates may occur
there, if they do at all. Farther north, that is likely to be even
more of the case.
Farther south in the county, accumulating snowfall also looks
likely, but convective banding may not be as much of a player
there. Latest NBM and hi-res guidance suggests 3-5" for I-40 east
of Kingman, 1-3" for Kingman proper, and similar amounts up on
the Hualapai mountains.
As a result, a Winter Weather Advisory was issued for all of
Mohave county from 18Z Tuesday through 00Z Thursday.
.LONG TERM...Thursday into the Weekend.
Most of the winter precip should be clear of the region by
Wednesday night with impressive agreement among ensemble members
that the low will be east of Mohave by Thursday. This will begin a
period of gradual increasing temperatures heading into the
weekend, but yet another shortwave is expected to push southward
by Friday and temper warming as well as bring gusty northerly
winds to the area, most notably at the CRV. More wind products may
be on the table for this period Friday and/or Saturday.
By the late weekend and into early next week, broad agreement on
further warming due to ridge building appears in the cluster
analysis with much quieter conditions looking more likely.
&&
.AVIATION...For Harry Reid...Gusty southwest winds will continue
with gusts to around 30-35 knots through this afternoon. Winds will
relax some later this evening but may remain breezy overnight.
Confidence on the forecast wind speeds and direction is moderate for
tonight, with some potential for winds decreasing and shifting to
the northwest briefly between 03-06Z Tuesday. By 13-14Z Tuesday,
winds will increase from the south to southwest again, with similar
gusts to 30-35 knots. Low level turbulence will remain through
Tuesday, and low level wind shear is possible tomorrow morning-
afternoon. Skies will remain mostly clear with some FEW aoa 10-15
Kft through this afternoon. Ceilings will briefly decrease tomorrow
potentially dropping to around 5-7 Kft with the passing frontal
system.
For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty west to southwest winds will continue with gusts
to around 30-40+ knots through this afternoon. The exception being
at KBIH where gusty north winds will remain with gusts around 20-30
knots through this afternoon. Winds will relax some later this
evening but may remain breezy overnight, with gusty west winds
remaining across western San Bernardino impacting KDAG. Similar
winds and speeds are expected to return Tuesday. SCT to BKN skies
aoa 7-10 Kft will be possible with a frontal passage tomorrow.
Fairly low chance for precipitation at most of the TAF sites, with
best chances possible (30-40%) at KDAG.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather including strong winds, damage, dust
storms, or travel impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
DISCUSSION...TB3
AVIATION...Peters
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