Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/12/22
Area Forecast Discussion
National Weather Service La Crosse WI
1056 PM CDT Mon Apr 11 2022
.DISCUSSION...(Tonight through Monday)
Issued at 230 PM CDT Mon Apr 11 2022
Key Messages:
- Severe storm threat Tue evening, mainly along and south of I-90.
Large hail the main concern.
- Decreasing threat for severe storms Wed - trends shifting it east
of the local area.
- Windy Thursday. Gusts 40+ mph for some. Wind headlines likely.
- Colder 2nd Half Of The Week
* STORM SYSTEM EVOLUTION: models coming together
While SPC cluster analysis continues to show the GFS and EC sitting
predominately in their own corners of the model world, those corners
are a lot closer together now. The GFS still occluded the system
faster on Wed, thus pushing its associated cold front across the
region quicker (15z) compared to the EC (21z). The EC has sped up a
bit though, while the NAM favors the GFS`s movement.
* TUE NIGHT: Storms...Strong, Severe Risk
Warm front. Where is the warm front? Basically, where would storms
be elevated and where could they be surface based. That is the main
question. Considerable warming in the low layers provides a stout
cap north of the front, with a lot of dry air above the cap.
Broad low level warm air advection spreads northward across the
region in the afternoon, an coupled with an increase in 850 mb
moisture transport/jet, should be enough to kick off some showers,
perhaps a few storms (non severe). With the ample dry air in the mid
levels, how widespread these showers are isn`t clear.
Meanwhile, off to the southwest an increasingly warm/moist airmass
will be pulling northward into a dry line hanging out from eastern
NE southward. Expectation is for storms to kick off by late
afternoon in this region, and with ample instability and relatively
longish, looping hodographs, should quickly upscale into supercells
with a tor risk. Most models in favor of this initiation point,
except the HRRR. While the HRRR does pop convection along the
boundary, it also suggests some storms quickly develop over north-
central IA/south-central MN during this time. With the warm front
farther south, these would have to be elevated containing only a
large hail risk. However, the HRRR is also more aggressive with the
push of moisture northward, as much as 10 degrees warmer with sfc
Tds over NE IA (compared to the rest of the model suite). Thus, its
likely eroding the cap faster, with more instability to play with,
resulting in the initiation. It being the outlier, will file it away
to keep an eye on, but keep our attention off to the west.
These storms will track east northeast toward the area as the
evening wears on while that warm front also gradually pushes north,
potentially reaching I-94 by midnight. Expect the storms to become
more linear in nature as they near the forecast area, more by mid
evening. Again, where the warm front lies is key as the hefty 0-1km
shear won`t be realized north of the warm sector. Severe threat
continue to focus on hail, but some wind from potential bowing
segments south of the warm front would be possible. Also, if a
storm can root to the warm front for a bit, backing winds would
enhanced the low level helicity and thus a tornado threat. Most of
the attention will be early on and focused on parts of northeast IA,
with decreasing instability gradually resulting in a lessening of
the severe threat as move past midnight.
Bottom-line: severe threat Tue evening, mostly after 8 pm thru
midnight. Hail the primary threat. Secondary threats would be wind
from storms south of the warm front with some tor potential from any
storm the tracks on that boundary. Focus is mostly NE IA, into SE MN.
* WEDNESDAY: Storm chances?
Warm front, low level warming a loft will be shifting northward into
northern WI early Wed morning while the storm system`s north-south
hanging cold front drags eastward across the local area. GFS and NAM
get it through by 15z. Showers, perhaps a few storms but little if
any severe risk. The slower EC (getting it east in the early
afternoon) would have some potential for stronger storms to get
going before it pushes into eastern WI. The EC also suggests a lot
more QPF as the slower solution allows for a shortwave to kick
through the upper level trough, right across the local area. Broader
area of rain develops in this scenario, but post front (limited
instability, limited thunder threat). At this time, think the risk
for severe storms locally is low...with increasing chances as you
work eastward toward eastern WI/eastern ILL for the afternoon.
* WINDY THURSDAY: gusts 40+ mph...wind headlines likely
Sfc pressure gradient tightening up as the sfc low lifts northeast.
EC continues to be the stronger model when it comes to sliding
higher gusts across the forecast area, but has backed off some
compared to some of its previous runs. Using KRST as a proxy, the
11.00z EPS has dropped mean wind gusts into the mid 40s with only 6
of its members peaking north of 50 kts. For comparison, the 10.00z
run had a mean in the upper 40s with 17 members above 50 kts. ECMWF
MSLP anomalies also checking in lower, mostly -2.5 to near -3 (was
closer to -4 just a day ago). This is more in line with the NAEFS
sfc pressure anomalies.
All in all, it`s going to be windy, likely kicking in overnight Wed
and persisting through the better part of the day Thu. Gusts peaking
into the 40s kts look reasonable at this time. Wind Advisories look
likely for a bulk of the area at this time.
* SNOW: chances Thu, maybe lingering into Fri?
Snow has shown a shift northward with the EC lifting quicker
northward into southern Canada on Thu. Deformation region not really
in play for the local area anymore, but good low level lapse rates
(8+ C/km 1000:800mb) and lingering low level moisture should be
enough for spark some snow showers...currently favored north of I-
90. Potential for a few more snow showers Fri, this time more
associated with bits of upper level shortwave energy on the backside
of the exiting storm. Again, mostly confined to the north. Any
accumulation looks minor at this time and confined to cold, grassy
surfaces.
* QPF: how much?
For QPF, the EC remains the wetter of the models but has continued
to back off its previous higher end amounts. Latest EC closer to 2"
now for its max run total QPF through 00z Fri. GFS and NAM closer to
1" for a max (matches well with the SREF).
* COLD END OF THE WEEK: colder air returns
Good push of cold post the storm system starting late Wed night with
not much change in the airmass expected through the weekend. EC
ensemble members keep in colder than normal through at least the
middle part of next week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1056 PM CDT Mon Apr 11 2022
An strong area of low pressure will track across Nebraska and
southern Minnesota Tuesday and Tuesday evening. A tight pressure
gradient around the low will produce gusty southeast winds a both
sites from the middle of the morning through the evening. Expect
the gusts to approach 30 knots at times during the late afternoon
and early evening. Showers are expected to develop ahead of the
system and start impacting both sites late in the afternoon into
the evening. VFR conditions ahead of the showers should go down to
MVFR as the rain saturates the lower levels of the atmosphere.
Some IFR could occur as well, but confidence is not high enough to
include at this time. Also some potential for thunder to occur,
but again confidence on timing and location not high enough to
include right now.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Rieck
AVIATION...04
Area Forecast Discussion
National Weather Service Corpus Christi TX
706 PM CDT Mon Apr 11 2022
.MARINE...
Winds across the bays are below SCA criteria, therefore the SCA
was allowed to expire at 7 pm. Winds are expected to be weak to
moderate to at times moderate across the bays overnight. Winds
have also fallen below SCA across the coastal waters, but seas
remain 7 to 9 feet. In addition, some of the guidance indicates
winds restrengthening across the coastal waters to around 20 knots
overnight as the LLJ strengthens.
&&
.PREV DISCUSSION... /Issued 644 PM CDT Mon Apr 11 2022/
AVIATION...
MVFR CIGs expected this evening across ALI, CRP and VCT TAF sites.
Cigs are expected to lower to IFR levels after 03Z for these
sites, but a low level jet will strengthen overnight which may
lift CIGs to generally MVFR levels after 08Z. The LLJ is forecast
to increase to 35-40 knots, however elevated surface winds should
preclude low level wind shear. Across the western TAF sites, COT
may briefly drop to MVFR by early Tuesday morning while LRD is
expected to remain generally VFR. An upper disturbance will bring
a chance of convection to S TX after 08Z with the convection
moving from southwest to northeast. Mainly showers are forecast
initially, then the chance of TSRAs increases by mid morning Tue.
The better chance for convection will be across the eastern areas.
Convection ends and conditions improve to VFR from southwest to
northeast Tuesday afternoon with VCT likely the last to improve.
The strongest storms could occur across the VCT TAF site where the
better instability is expected to be located.
PREV DISCUSSION... /Issued 321 PM CDT Mon Apr 11 2022/
SHORT TERM (Tonight through Tuesday Night)...
The low level jet with winds between 30-40 knots is expected to
develop once again this evening and into tonight as a shortwave
moves across the area. Convection Allowing Models (CAM), with the
HRRR being the most aggressive, are showing showers developing early
tomorrow morning before sunrise moving from the southwest to the
northeast. As daytime heating begins after sunrise, CAM are showing
convection developing across South Texas throughout the day with
most of the activity pushing offshore late tomorrow afternoon.
However, global models are showing another window of showers and
storms traversing across the Victoria Crossroads late tomorrow
afternoon and into tomorrow evening, from 00z to 06z which the CAM
are not currently showing. Regardless of which models verify the
best, rain chances are expected to taper off late tomorrow evening
and into tomorrow night. With SPC continuing to highlight the
northeastern portion of the Brush Country and Victoria Crossroads
under a marginal risk of severe weather, any storm that develops
will have the potential to become strong to severe.
Despite the increase in rain chances, our fuels remain extremely
dry with our Energy Release Component between the 90th and 96th
percentile. With temperatures in the upper 90s to near 104 degrees
across the Brush Country and Rio Grande Plains and dew points below
65 degrees, relative humidity values will be below critical levels
which could lead to elevated fire weather conditions tomorrow.
Temperatures tomorrow are expected to be 5 to 8 degrees warmer than
today which areas near the coast in the upper 80s to lower 90s while
areas further west warm up to near 104 degrees. Overnight low
temperatures will continue to be mild which temperatures ranging
from the upper 60s to mid 70s.
LONG TERM (Wednesday through Monday)...
Overall, not much change in the current thinking with the long term
forecast. We start out the period with an upper level low rotating
across the Plains while a cold front sags south towards South Texas.
Ahead of the front, a dryline looks to wobble across the Brush
Country on Wednesday, leading to another period of elevated to
critical fire weather concerns as RH values drop to 8 to 15%. As a
result, a Fire Weather Watch is in effect for the Brush Country and
portions of the Coastal Plains Wednesday afternoon. The cold front
looks to catch up to the dryline Wednesday evening into Thursday
morning. There remains some model inconsistencies in regards to how
strong and how far south the front will go. The NAM parks the
dryline across the Coastal Plains and advances it back to the
northwest before the front arrives. Meanwhile, the GFS/CMC/ECMWF
absorb the dryline into the front and stalls it along our southern
tier of counties before treating back to the north on Thursday. Not
expecting much in the way of precip with this FROPA as a result of
significantly drier air aloft and a stout H85 cap.
Rain chances are reintroduced into the forecast on Friday as a
increasing PWATs interact with a passing upper level shortwave.
Onshore flow looks to continue as we head into next weekend with
another potential front moving our way late in the weekend into
early next week.
The temperature forecast isn`t...great. Highs on Wednesday look to
climb to around 100 degrees out west as we clear out behind the
dryline. Temperatures along the coast look to settle into mid 80s to
low 90s. Area-wide highs will be roughly 10 to 15 degrees above
normal for mid April. Our mid week cold front looks to knock off
temperatures a handful of degrees with highs in the low 80s along
the coast to the low 90s out west. A warming trend will kick in late
in the work week and continue through the weeekend with highs
approaching triple digits out west.
MARINE...
Moderate to strong onshore flow will continue tonight and tomorrow
before increasing to strong levels tomorrow night. Isolated to
scattered showers and thunderstorms will be possible late tonight
(after midnight) through tomorrow evening, with the potential for
gusty winds within thunderstorms. The Small Craft Advisory is
expected to continue through 00z today for the bays and until
tomorrow evening for the offshore waters. Strong onshore flow and
elevated seas will maintain Small Craft Advisory conditions
through Thursday morning. Winds look to relax for a brief period
Thursday before moderate to strong easterly winds kick back in
through Friday morning. Rain chances return on Friday as
southeasterly flow becomes reestablished and continue into the
weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 72 88 72 93 66 / 30 40 10 0 0
Victoria 71 85 71 90 60 / 30 40 20 10 0
Laredo 73 103 72 100 67 / 20 20 0 0 0
Alice 71 96 70 99 63 / 30 40 10 0 0
Rockport 71 83 72 86 66 / 20 40 10 0 0
Cotulla 72 104 70 100 60 / 30 40 10 0 0
Kingsville 71 92 71 97 65 / 30 40 10 0 0
Navy Corpus 71 84 71 82 68 / 30 30 10 0 0
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk through Tuesday evening For the following
zones: Aransas Islands...Calhoun Islands...Kleberg
Islands...Nueces Islands.
Fire Weather Watch from Wednesday afternoon through Wednesday
evening For the following zones: Duval...Jim Wells...La
Salle...Live Oak...McMullen...Webb.
GM...Small Craft Advisory until 7 PM CDT Tuesday For the following
zones: Coastal waters from Baffin Bay to Port Aransas out
20 NM...Coastal waters from Port Aransas to Matagorda Ship
Channel out 20 NM...Waters from Baffin Bay to Port Aransas
from 20 to 60 NM...Waters from Port Aransas to Matagorda
Ship Channel from 20 to 60 NM.
&&
$$
TE/81...SHORT TERM
XX/99...LONG TERM
Area Forecast Discussion
National Weather Service Des Moines IA
656 PM CDT Mon Apr 11 2022
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Monday/
Issued at 246 PM CDT Mon Apr 11 2022
Key Messages:
-- Severe storms possible, most likely late afternoon and more so
Tuesday evening
-- Strongest winds on Thursday, gusty winds Tuesday and Wednesday
-- Cooler for the latter half of the week
Details: A common weather theme for Iowa over the last six weeks
will once again play out this week as convection precedes a mid-
level low closing off and meandering over the region with breezy to
windy conditions and light rain/snow perhaps following behind it
over or just north of Iowa. Today is the quiet weather day of the
week with light winds and a good amount of sunshine as surface high
pressure pushed east of the state this afternoon. GOES-East upper
level water vapor imagery shows the mid-level shortwave that moved
through yesterday lifting towards Hudson Bay while our next weather
system has moved over Oregon. This will be the main mid-level
feature and as that moves east over the Rockies, will have surface
cyclogenesis occurring over northeastern Colorado. This mid-level
shortwave and surface low will move eastward through Nebraska during
the day. Ahead of it, southerly flow will draw more humid air
northward as a warm front extending eastward from the low lifts into
the state with a strong push of low level theta-e advection. There
remains the potential for elevated storms with the main hazard being
severe hail (around or less than an inch) as this theta-e advection
moves through in the morning and early afternoon. However, guidance
is struggling to generate much in the way convection outside of the
ECMWF over northern Iowa and the convective allowing models largely
show light showers. In addition, winds beneath the inversion could
be quite gusty with FOD sounding showing top of mixed layer winds
near or above 45 mph and sustained winds close to 30 mph for a few
hours over northern Iowa. Warm air advection is not the typical
regime for gusty winds, but this could be a candidate for a wind
advisory still.
Following with and behind the theta-e surge will be a band of low
stratus that will lift north and then northeastward per the 00z/12z
HREF. It looks like there will be clearing in the warm sector over
at least southwest Iowa as the warm front lifts into Iowa with
greater uncertainty in clearing farther northeast. From here, there
appear to be at least two possible outcomes in the afternoon. The
first are the models with the faster surface low progression. The
HRRR is the farthest east by 00z with the surface low with the RAP
and GFS lagging just a bit farther west closer to Sioux City. With
these models being farther east with the low compared to the NAM and
ECMWF, they pull the warm front 30 to 60 miles farther northeastward
up towards Highway 20. HRRR and RAP forecast soundings at FOD show
the elevated warm layer eroding with any inhibition breakable as the
warm front reaches a location. Surface based CAPE will be around or
in excess of 3000 J/kg and with the surface low`s closer proximity
to north central Iowa, backed surface winds are helping to increase
the storm relative helicity. Deep layer shear over 60 knots and 0-
1km SRH values are in excess of 300 m2/s2 and hodograph curvature in
the low levels are showing a model environment favorable for
supercells capable of tornadoes and damaging wind gusts and hail
would also be hazards. This is not certain and will depend on the
low and warm front position and enough forcing to break the
lingering cap with the more likely time for stronger forcing toward
and after dark. The other solution of the NAMNest, NAM, and ECMWF
shows the low pressure moving slower with it over eastern Nebraska
at 00z. Thus, the warm front is farther south in Iowa and with the
low farther west there is a lack of forcing to overcome the
inhibition. Thus, with forcing lacking, inhibition would not be
overcome leading to less if no convection. So, the afternoon is far
from set on the possible outcome and will need to watch the low and
warm front positions tomorrow as well as incoming guidance over the
next 18 to 24 hours.
There is better agreement and confidence that as the low and
attendant cold front moves through eastern Nebraska into western
Iowa, storms will develop along the boundary. In the vicinity of and
just ahead of the boundary, surface CAPE will be in excess of 2000
J/kg and deep layer shear will be supportive of severe storms as
they organize into a QLCS line. The low level jet will crank up over
60 knots and and this will be a concern for any storms that entrain
these winds into a downdraft. Further, 0-3km CAPE remains favorable
for vortex stretching and the 0-3km shear is certainly strong enough
for mesovortex generation. However, it will depend on the shear
vector having a favorable orientation to the line or surges/bows in
the line to achieve QLCS tornadoes. As the line continues to
progress toward central Iowa, it may become cold pool dominant and
surge ahead bringing an end to the tornado threat with damaging wind
gusts perhaps lingering a bit longer as it moves across our area.
So, to summarize, there could be three rounds of storms tomorrow
through tomorrow night. The first is the most unlikely, but if it
were to occur they could contain elevated storms capable of
marginally severe hail. The second potential and uncertain round
would be along the warm front with storms capable of tornadoes,
damaging wind gusts, and large hail. And finally and with the most
certainty is the line of storms that will enter the state Tuesday
evening into the overnight. This could still have surface based
storms with tornadoes along the line and damaging wind gusts
possible. The latter two rounds will also feature fast storm motions
and thus if tornadoes do form, the storm motion will contribute to
higher damage on right of the centerline.
With the storms pushing through our area and the cold front looking
to be east of our forecast area with the exception of the 00z CMC,
the severe risk will largely if not completely be east of our
forecast area. SPC day 3 outlook has trended in that direction and
the Colorado State`s machine learning random forest outlook as well
as the CIPS Experimental Analog-Based Severe Probability Guidance is
showing the risk east. Therefore, the focus on Wednesday after the
storms move out early will be on the cold air advection, which will
have temperatures over western Iowa only rising a few degrees before
steading off. Winds from the west will increase through the day and
become gusty as the closed low winds up and spins over Minnesota.
The strongest winds continue to be on centered on Thursday. The 00z
ECMWF extreme forecast index continues to have a consensus of
ensemble members (>80%) with an unusual wind event compared to model
climatology, though this along with the shift of tail of 1 have
shifted northward. The experimental NBM v4.1 24 hour wind gusts
probabilities have also decreased such that high wind warning
criteria is not as likely. However, wind advisory still looks highly
likely for northern Iowa with wind gusts of 45 knots possible
looking at NAM and GFS BUFKIT soundings. With the low wrapping up a
bit farther north, the rain or snow over northern Iowa may end up
just being north of the border. With the low slow to depart, cool
conditions will persist into the weekend.
&&
.AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/
Issued at 654 PM CDT Mon Apr 11 2022
VFR conditions are expected to remain across all terminals through
mid morning Tuesday. Winds will shift southeasterly overnight,
turning breezy during the mid to late morning with gusts towards 25
to 35 knots and brief periods of wind shear, highest across northern
Iowa. Ceilings are expected to lower from southwest to northeast as
the warm front lifts across the state with isolated to scattered
showers, bringing MVFR and brief periods of IFR conditions in the
late morning through the afternoon.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Ansorge
AVIATION...Bury/Cogil
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1103 PM EDT Mon Apr 11 2022
.AVIATION...
High mean RH through 700- 600mb will persist through roughly 06Z
this evening then scours out rapidly for the remainder of tonight.
Models show strongly anticyclonic flow trajectories through much of
Tuesday supporting fresh and active subsidence across Southeast
Michigan. Prefer to carry SKC as the cloud group. 650-750mb
Anticyclone center is forecasted to push across Southeast Michigan
around 18Z. Fairly abrupt lower level moisture return is expected
after 00Z Wednesday 4/13.
.DTW THRESHOLD PROBABILITIES...
* None
&&
.PREV DISCUSSION...
Issued at 336 PM EDT Mon Apr 11 2022
DISCUSSION...
Mostly clear skies took hold early this afternoon following the
morning cumulus and thundershowers allowing for ample sunshine which
combined with ongoing modest WAA, has led to overachieving
temperatures in the upper 60s to low 70s. Cirrus will continue to
stream into the region with increasing cumulus development along the
Ohio border and Metro Detroit areas as warm sector showers spill
north of the border. These showers increase in coverage into this
evening as the cold front sweeps across lower MI. Mixed bag in the
morning model runs in relationship to the degree of response along
the front. Hi-res solutions such as the HRRR or ARW depict stronger
frontal forcing over southern lower MI allowing the generation of
light showers between 20-03Z as north as Huron county. Conversely the
coarser model solutions such as the GFS, NAM12, and Canadian keep
strongest forcing to our south across OH/IN with only the southern
CWA (south of M-59) getting clipped by rain. Given radar trends over
southern central MI the past couple hours, will err toward the hi-res
solutions bringing lower-end chance PoPs up to the I-69 corridor
with high-end slight chance north through the Thumb.
Drier airmass settles in behind the cold front leading to a mostly
sunny day Tuesday. Another warm front then lifts through the region
late Tuesday evening into the overnight hours kicking off fairly
substantial WAA. 850mb temps climb over the course of the night from
4-5C to 10-12C. A lack of accompanying moisture limits shower/t-
storm development along the front Tuesday night as main theta-e
plume is initially draw west over WI and western MI. This plume
eventually spills east by early Wednesday morning offering the
potential for some development over SE MI dependent on the location
of the front. Currently front looks to be at least north of M-59 by
this time, if not already pushing north of I-69. As such will hold
higher PoPs over the northern CWA and taper them off down towards
Detroit. Very warm conditions hold daytime Wednesday as highs top
out around 70 with dewpoints reaching into the upper 50s, perhaps
even the low 60s. Fair amount of consensus in mid-range solutions in
a ribbon of PV racing north from the Mississippi valley into the
central Great Lakes daytime Wednesday. Early summer type environment
with weak instability already in place combined with this wave
should be more than sufficient for widely scattered to numerous
disorganized showers and storms to develop throughout the afternoon
and evening.
Region remains under a marginal risk with slights to our west and
south for convection late Wednesday evening into early Wednesday
night. Cold front reaches the area by late Wednesday evening with a
north-south oriented line of convection in advance. While some
discrepancies exist, this line is progged to reach SE MI somewhere
between 03-06Z. Main point of concern in regards to severe potential
is this timing places it within the normal diurnal decrease in
instability with forecast profiles showing CAPE falling below 500
J/kg and low level lapse rates dropping to around 5C/km. Main factor
in support for severe potential is shear as values top out in the 30-
40kt range. How the line progresses across the state will be
something to keep an eye on as there is some signal that convection
is stronger across IN/OH as well as over west Michigan weakening the
portion of the line moving through SE MI.
Parent low over the northern Plains rapidly deepens early Thursday
as the upper trough turns so negatively-tilted it essentially goes
neutrally-tilted. Rapidly tightening pressure gradient in
combination with increasing diurnal mixing heights likely leads to a
windy Thursday afternoon and evening. Gusts in that period could
approach advisory criteria (40mph). Winds weaken into Thursday night
with the typical shallower nocturnal mixing heights though still
likely on the breezier side given the gradient. Gradient gradually
weakens over the course of Friday as the low weakens and moves over
the James Bay.
MARINE...
A low pressure system is located just north of Lake Superior this
afternoon and is dragging a frontal boundary across the central
Great Lakes. Winds will begin to decrease this afternoon into the
evening as warm air lifts into the region resulting in more stable
surface conditions across the waters. Thus, will let the Small Craft
Advisory drop off at 4 PM EDT. As winds decrease, an area of showers
will lift through the southern marine areas from southern Lake Huron
to western Lake Erie through this evening.
More light and variable flow is expected on Tuesday with the passing
of a weak high pressure. Winds will then pick up out of the
southeast Tuesday evening as the next low pressure system develops
across the Central Plains. Winds stay elevated through Wednesday as
flow turns more southerly. This will lead to renewed Small Craft
concerns by Wednesday morning. Winds ramp up further on Thursday as
a cold front drives through the region. Gusts over the open waters
of Lake Huron will approach 30 knots for Thursday. Widespread
thunderstorms with some possibly strong expected for Wednesday as
well.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....99
DISCUSSION...KDK
MARINE.......AA
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1014 PM EDT Mon Apr 11 2022
.SYNOPSIS...
Temperatures should run above normal most of the week under an upper
level ridge. Precipitation chances generally will remain low through
Wednesday. A cold front likely will push across the region Wednesday
night and Thursday, bringing chances for showers and storms. Expect
more chances for showers and storms by late in the weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1000 PM: Not much change this go-round. As anticipated,
some clearing is evident in satellite imagery over the western
tier as the driving shortwave axis moves over eastern NC and
upper forcing wanes. Light winds with occassional sub-advisory
gusts are still underway. Fire Danger Statement has expired for
the NC Piedmont as RHs slowly crawl back into the 40s and higher;
do not anticipate needing another one tomorrow.
Otherwise, high pressure offshore in the western Atlantic will
extend into the Southeast US while a cold front approaches from the
west before stalling to our northwest early Tuesday morning. This
will lead to southwesterly flow through the near term forecast
period. Breezy winds can be expected to continue into tonight
across the mountains as the pressure gradient tightens ahead of the
approaching system. Winds are expected to remain below advisory
criteria overnight but a few gusts near criteria cannot be ruled
out across the higher elevations.
A second short wave will allow for upstream convection to develop
overnight into daybreak Tuesday across the Tennessee Valley. This
convection looks to fall apart as it pushes across the southern
Appalachians, per the latest CAMS guidance. However, the HRRR
has been consistently pushing the convection as far as the
Foothills. For now capped PoPs to chance along the NC/TN border
and slight across the western mountains. Tuesday afternoon we have
the potential to see another line of upstream convection. However,
confidence remains low with this line as well as CAMS continue to
show activity falling apart as it crosses the Appalachians. For
this reasoning, capped PoPs to slight Tuesday afternoon across
the western mountains. Isolated thunder cannot be ruled out with
these storms, however instability looks rather limited, and many
model soundings still suggest that the majority of the forecast
area will remain capped through afternoon. Temperatures will be 5
to 10 degrees above climo throughout the near term forecast period.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 232 PM EDT Monday: The upper pattern continues to amplify
on Tuesday night and Wednesday while the upper ridge axis shifts
offshore, but this will not permit the stronger mid/upper forcing
or deeper moisture from making much eastward progress through
the day. Instead, we are left with a southerly low level flow
which has yet to bring much in the way of moisture return from
the Gulf by that time period. A few ridgetop showers are possible
but that is about it. High temps will feel warm...on the order
of ten degrees above normal...for Wednesday, and low temps will
be seasonally mild. The main event for the forecast period will
be the approach and passage of a cold front. This boundary looks
strong as it approaches from the west, with excellent forcing and
ample response in the form of strong/severe thunderstorms well to
our west Wednesday evening. The problem is...the forcing gradually
weakens as the front reaches our western doorstep by daybreak
Thursday...and it never regains its former stature on Thursday as
it moves through. Be that as it may, the GFS in particular still
develops sfc-based CAPE on the order of 1500 J/kg and shear on the
order of 30 kt east of the mtns Thursday afternoon, so while this
won`t be nearly as impressive as what happens in the mid-MS valley
Wednesday, it will still be sufficient for some decent potential
for organized strong/severe storms. Precip probs will be kept in
the likely range. The boundary should move off to the east by late
evening, taking the shower/thunderstorm chances with it. Not much
air mass change with the front, though.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 218 PM EDT Monday: Not much change for the end of the week,
with model guidance indicating that the cold front will clear the
fcst area by daybreak Friday and give us a brief break in the action
Friday and Friday night as sfc high pressure slides across in the
nearly zonal flow aloft. Confidence naturally is relatively low once
we get into the weekend as model guidance diverges significantly
as to the amplitude of the upper pattern. The more zonal GFS has a
series of difficult-to-pin-down waves moving along and affecting the
western Carolinas maybe on Saturday and maybe on Monday. Meanwhile,
the more amplified ECMWF is less excited about Saturday because
it keeps the old frontal boundary suppressed farther south into
the weekend, but much more excited about the prospects for rain on
Monday with a much stronger wave moving in from the west early in
the week. The fcst blends more or less wash out these differences
leaving us with a slight chance over the weekend building to
a chance of showers and storms on Monday, which at this point
is a preferable compromise. Temps should stay above normal,
until perhaps Monday if more amplified solutions provide either
widespread rainfall and/or some cold air damming potential.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR conditions expected through the TAF
period. A cirrus shield continues to ride up atop a broad ridge
across the Carolinas, and has developed SCT to BKN cloud decks
above 15 kft for all sites. A southwest wind continues to improve
moisture, but as upper support wanes, at least some clearing is
expected overnight. Near and immediately following daybreak, a
renewed pattern aloft results in additional VFR ceilings through
the late morning and into Tuesday afternoon. Still expect a few
showers to work their way into the mountains as a much deeper system
impacting east TN drifts into the Appalachians Tuesday afternoon
and evening. Have included a PROB30 to this effect in the KAVL
TAF as near-term guidance increasingly favors such a scenario.
Confidence remains low, however, and forecast is subject to change.
Otherwise, cloud cover late Tuesday is expected to thicken at all
sites, with falling VFR ceilings through the end of the TAF period.
Outlook: Moisture continues to deepen through midweek, with
better chances for flight restrictions developing late Wednesday
and Thursday. Dry high pressure returns on Friday.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...AP/MPR
SHORT TERM...PM
LONG TERM...PM
AVIATION...MPR
Area Forecast Discussion
National Weather Service Lake Charles LA
945 PM CDT Mon Apr 11 2022
.DISCUSSION...
The inherited Wind Advisory was allowed to expire at its scheduled
expiration time of 00z/19L based on obs showing sub-criteria
winds/gusts at that time. Otherwise, no changes to inherited
grids/zones looks needed this evening based on latest obs/trends.
Recent guidance also indicates all expected precip holding off
until after 12z across the forecast area...thus no evening update
is planned.
25
&&
.PREV DISCUSSION... /issued 645 PM CDT Mon Apr 11 2022/
DISCUSSION...
For the 04/12/2022 0000 UTC TAF package.
AVIATION...
Intermittent MVFR cigs noted at the southern terminals with VFR at
AEX. MVFR cigs will become more prevalent at all terminals over
the next few hours, and continue overnight. Wind gusts are
already beginning to taper off, but southerly winds will remain
elevated around 10 KT overnight. Cigs are expected to lift
slightly Tuesday morning, but remain in MVFR categories, with
winds again bcmg strong and gusty by mid-morning. Introduced VCTS
by late morning to early aftn as convection develops ahead of the
next disturbance. Carried PROB30 groups for the aftn with
convection expected to increase in coverage, although there is quite
a bit of uncertainty among hi-res models with respect to timing.
24
PREV DISCUSSION... /issued 426 PM CDT Mon Apr 11 2022/
SHORT TERM [Today through Wednesday]...
Mostly cloudy skies are currently being seen in the area. Temperatures
are currently in the upper 70s and low 80s with moderate to high
relative humidity. There is moisture present in the area and this will
continue over the next few days with onshore flow.
Gusty southerly winds are currently being seen in southern parts
of the area. Winds will decrease this evening. With a significant
pressure gradient present ahead of a frontal system, elevated
onshore flow will continue overnight which will likely inhibit any
significant fog formation.
Showers and thunderstorms will be expected tomorrow from the
morning into the afternoon and evening. The 18Z HRRR is indicating
sufficient CAPE and shear for the possibility of severe
thunderstorms. Damaging wind gusts, large hail, lighting, and few
tornadoes will be possible. PWATs are showing in the 1.8 to 2 inch
range which which indicates the possibility of flooding. HRRR
soundings also show significant moisture from the low-levels to
the upper-levels.
Showers and thunderstorms will be expected on Wednesday as well
with a frontal boundary remaining to our northwest. Another round
of severe weather will be possible as well on Wednesday with warm
temperatures and plenty of moisture.
55
LONG TERM [Thursday through Sunday]...
The upper air pattern will be generally characterized by zonal flow
with weak upper level disturbances bringing intermittent low chances
of precipitation Thursday through Easter Sunday.
Thursday will see post cold frontal northerly winds and diminishing
shower and thunderstorm chances over South Central Louisiana behind
the exiting shortwave. Slightly cooler and drier air expected
Thursday through Friday mornings, with lows in the mid 50s to near
60s both mornings. Highs in the upper 70s to near 80 Thursday. The
cool air mass behind the front will be very shallow and short lived
with the surface high moving east and southeast winds returning for
Friday.
With the higher moisture content within the airmass, along with the
intermittent upper level disturbances in the zonal flow aloft,
expect intermittent low end chances of showers and perhaps a
thunderstorm Good Friday through Easter Sunday. Expect low
temperatures in the mid to upper 60s, with highs in the lower to mid
80s.
08
MARINE...
Elevated onshore flow will continue over the next few days with a
tight pressure gradient present. Showers and thunderstorms will
be possible tomorrow and Wednesday. Some of the storms could be
severe. A Small Craft Advisory is currently present through
tomorrow.
55
LCH WATCHES/WARNINGS/ADVISORIES...
LA...Wind Advisory until 7 PM CDT this evening for LAZ033-041>045-
052>055-073-074.
TX...Wind Advisory until 7 PM CDT this evening for TXZ215-216.
GM...Small Craft Advisory until 7 PM CDT Tuesday for GMZ430-432-435-
450-452-455-470-472-475.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 67 81 68 81 / 0 70 50 90
LCH 67 79 67 80 / 10 80 40 70
LFT 67 80 68 81 / 0 70 40 80
BPT 68 80 69 81 / 10 60 30 60
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...Small Craft Advisory until 7 PM CDT Tuesday for GMZ430-432-435-
450-452-455-470-472-475.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
936 PM CDT Mon Apr 11 2022
.UPDATE...
Issued at 930 PM CDT Mon Apr 11 2022
The main tweak to the forecast through the day tomorrow was to
further back off of chances for any showers and thunderstorms.
An elevated mixed layer with exceptionally steep mid-level lapse
rates will be advected east-northeastward from the High Plains to
the Midwest on Tuesday in strengthening west-southwest mid-level
flow in advance of deepening low pressure tracking near the
Nebraska-South Dakota border. A weak short-wave should brush by
northern Illinois in the late morning, though lacking in moisture.
This will be followed by persistent height rises into the evening
while the mid-level lapse rates continue to steepen due to the
stout EML.
A warm front extending from the Plains surface low will
progress north through the area into the evening. Strong 850-950
mb warm and moist advection will develop into the region, and
cause lowering and thickening clouds as the warm front lifts
north, but this moistening and isentropic ascent appears unlikely
to punch through the EML "helmet". Small threat may exist in the
evening across far northern Illinois to pop elevated convection,
but better chance appears to be north of the state line. Given the
above described reasons, expecting the current level 1 severe risk
to be pared back to maybe a lower end highly conditional hail
threat in the far north given very steep lapse rates and strong
effective bulk shear. Overall, tomorrow will be another nice day,
except remaining chilly near the Illinois shore where influence
from the cold lake could keep east- southeast flow lingering until
late day or possibly as late as the early evening.
Castro
&&
.SHORT TERM...
Issued at 227 PM CDT Mon Apr 11 2022
Through Tuesday night...
Surface high pressure is crossing the area this afternoon while a
series of upper disturbances tracks northeastward over the
region. Expansive mid level high cloud cover is in place as a
result with some spotty areas of sprinkles or light rain which
will end by early evening. Cloud cover will decrease from west to
east through the evening. Westerly winds will become light and
variable this evening then turn southeasterly late tonight before
steadily increasing Tuesday morning. Surface low pressure will be
strengthening over the central high plains and moving eastward
through the day Tuesday. This will allow winds to further increase
later Tuesday through Tuesday night with gustiness increasing
during the afternoon from west to east.
The strengthening flow aloft will push warmer air into the region at
the surface and aloft, with a sharp warm layer moving in a few
thousand feet above the surface. This will provide a sharp cap to
surface based thunderstorm development as larger scale ascent
increases ahead of the system. As previously noted, the best
chance for the combination of ascent, incoming moisture and weaker
capping inversion will be on the leading edge of the warmer air
aloft Tuesday afternoon into early evening. This may bring some
elevated thunderstorms across the area which would have some hail
potential given steep mid level lapse rates and elevated
instability. Right now most areas look dry and will continue with
only slight chances for shower/thunderstorms into Tuesday evening.
There are better chances for thunderstorms Tuesday night for a
couple possible reasons. First is a shortwave trough forecast to
track up the Ohio Valley overnight which may bring thunderstorms
across at least parts of the area. Another possible factor would
be remnant storms ahead of a quickly advancing cold which higher
res guidance sources seem to favor. At this point, this faster
arrival of convection tied to the cold front toward or soon after
daybreak Wednesday morning is not favored. Additional details will
follow in the long term section of the discussion below.
Temperatures will not cool much Tuesday night as gusty southerly
winds remain in place allowing for a very mild night in the 60s.
MDB
&&
.LONG TERM...
Issued at 238 PM CDT Mon Apr 11 2022
Wednesday through Monday...
Primary forecast concerns remain severe weather potential on
Wednesday and then very strong winds on Thursday.
Low pressure will be lifting across the northern Plains/upper
midwest Wednesday morning as a strong cold front approaches the
local area from the west. There is still quite a bit of
uncertainty has to how this system evolves through Wednesday
night. While some trends are emerging, one fairly large
uncertainty is the potential for any ongoing convection
Wednesday morning, either from decaying activity moving in from
the west or new convection developing right across the area. Just
about all the models are showing the first surface low occluding
with another surface low developing over northern or central IL
Wednesday afternoon. Given the support for this solution, the cold
front is most likely going to slow thus the affect of any morning
convection/precip may not be much. Though best timing may still be
from mid Wednesday afternoon through early/mid Wednesday evening.
The 12z GFS has certainly trended closer to the more consistent
ECMWF and is also more robust with its convection footprint. If
there is no secondary surface low development or its weaker/later,
its possible the cold front may push through faster, which the
15z RAP would suggest at the end of its run.
As for the severe potential, damaging wind gusts would be the
primary severe weather mode but if a surface low is able to
develop near or in the local area in the afternoon, then there
would be the potential for a few tornadoes. Given precipitable
water values are in the 1 to 1.25 inch range, heavy rain will also
be possible. Overall speed of this activity should limit flooding
potential, but given the overall damp/wet ground, there will be at
least minor flooding possible. Overall, current forecast has these
expected trends handled fairly well. Main changes were to
increase thunder coverage Wednesday afternoon/early evening and to
decrease pops faster Wednesday night.
Winds during this time period are tricky. There is an overall
decrease in the prevailing winds for Wednesday afternoon/evening,
due to the potential new surface low development, and followed
this trend by lowering speeds/gusts. It will still be breezy, but
perhaps gusts will only be in the 25-30 mph range. Winds
Wednesday night will likely be dependent on the strength of the
second area of low pressure, which the ECMWF deepens quickly over
Lake Michigan, this will yield much stronger winds into the
overnight time period, early Thursday morning. Confidence during
this time period is fairly low. By Thursday, there is good
agreement for strong west/southwest winds across much of the area
and previous forecast had near advisory level winds for the
northern half of the area and maintained those winds with this
forecast.
After a few weak disturbances Friday through Sunday, the models
really diverge for early next week with the GFS cool, but mainly
zonal and then the ECMWF has a large upper low parked over the
Great Lakes with is supported by the Canadian. Looks like there is
support for this from both models in previous runs. Too early for
details, but more cool/showery weather may be in store for the
area. cms
&&
.AVIATION...
For the 00Z TAFs...
The concerns include:
* Gusty east-southeast to southeast winds on Tuesday
* Low MVFR CIGs to possibly IFR late day into Tuesday evening
* Very low chance for widely isolated TS Tuesday PM
* Low chance for a period of DZ and reduced VSBY Tuesday evening
* LLWS possible Tuesday evening
Strong low pressure tracking across Nebraska will send a warm
front north across the area Tuesday evening. Prior to this, expect
east-southeast to southeast winds to increase and become gusty.
Lake influence will probably keep ORD and MDW more easterly until
later in the afternoon, with a chance of a direction just north
of east from mid day through the early afternoon. Peak gusts could
approach 30 kt in the late afternoon, especially at RFD. As the
front approaches in the late afternoon, also expect CIGs to
deteriorate, with at least lower MVFR favored into the evening.
There`s a threat for drizzle to develop if IFR CIGs materialize
with a deep enough saturated layer above it. Should drizzle
develop, then a period of reduced VSBY may also occur.
The warm front should push north fairly quickly, and cause winds
to shift to due southerly toward or just beyond 06z Wednesday.
In addition to the CIG and VSBY concerns, the atmosphere will
become unstable aloft through Tuesday, though most guidance
suggests that a stout capping inversion will prevent convection
from developing locally, with perhaps RFD area having a relatively
higher (but still low) chance. Finally, strengthening south-
southwest winds from an intensifying low level jet may require
mention of LLWS in later TAFs for the Tuesday evening timeframe
and appears quite likely to be needed early Wednesday beyond
current TAFs.
Castro
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion...UPDATED
National Weather Service Little Rock AR
636 PM CDT Mon Apr 11 2022
.AVIATION...
Updated for 12/00Z terminals...
Flight conditions over the next 24 hours will largely be dictated
by the mesoscale environment, with initial convection, then
diminishing intensity, then mvfr or ifr conditions becoming
prevalent. Another potential round of convection by late tomorrow
afternoon, but if this pans out, the terminals will mostly be
dealing with this after the end of the current period.
&&
.PREV DISCUSSION...(ISSUED 300 PM CDT Mon Apr 11 2022)
SHORT TERM...Tonight Through Tuesday Night
Seeing a `break` in the convection acrs the FA early this aftn.
Abundant low lvl moisture contd to advect into the region today,
thanks to gusty S/SE winds. Sfc dewpoints were already well into the
60s ovr cntrl and srn AR.
Low clouds have hampered daytime heating in many locations, but have
started to see breaks occurring ovr the SW half of the FA. With
temps warming well into the 70s and lower 80s in this area, SBCAPE
values are now in the 2-3K J/KG range. Data fm our 20z RAOB here at
LZK shows that the low lvl capping inversion has all but eroded.
This was also evident by the sctd SHRA/TSRA starting to form ovr Wrn
AR.
Little chg in the overall fcst thinking this aftn. The HRRR has been
the most consistent of the model suite contg to depict discrete
cells quickly forming later this aftn in the warm and unstable
airmass. Large hail, damaging winds and isolated tornadoes rmn
possible.
The bulk of the activity wl start to dcrs in coverage and intensity
later this evening as assocd upper support shifts NE of AR. We still
look to be in a lull as far as rain chcs go heading into Tue. the
persistent SW flow aloft wl bring yet another upper impulse into the
region late Tue/Tue night. PoPs wl incrs fm the SW starting Tue aftn
and bcm widespread Tue night ovr the FA. Strong and severe storms wl
again be possible, with all modes of severe wx possible. The
unsettled wx wl persist into Wed.
LONG TERM...Wednesday through Sunday
An upper level trough looks to be situated just to the west of the
state Tuesday night as continued unsettled weather is likely through
the beginning of the long term period. Strong to severe
thunderstorms are looking more likely Wednesday as instability and
wind shear look to be favorable.
Global and ensemble guidance continues to be in agreement this
afternoon indicating some shower/thunderstorm activity out ahead of
a main line that pushes through the state Wednesday afternoon and
evening with pop up convection out ahead of the line. This timing
will be critical for the system because an afternoon/evening impact
will give abundant amounts of instability (1500+ J/kg CAPE), high
wind shear, and dew points in the upper 60s and lower 70s.
Additionally, models show SRH values of 200+ m2/s2. All of which
cause me concern as this would be more than favorable to support
large hail, damaging winds, and tornado development. These
ingredients have been lacking in the past as most systems have
impacted the state during the overnight hours.
So how could Wednesday play out? My current thinking is there will
be storms out ahead of the main line (the cold front) as early as
Wednesday morning with a line of thunderstorms moving across the
state by the afternoon and evening hours. Should some cells be able
to get out ahead of this line, they would pose the greatest risk of
being tornadic with wind shear values >50 kts in addition to large
hail. As the main line moves across the state Wednesday
afternoon/evening it is likely we turn our attention to a damaging
straight-line wind and large hail threat...although tornadoes cannot
be ruled out.
With changes still possible the next couple of days, make sure the
information you receive between now and then is from a reliable
source. Lastly, do not let your guard down over the next several
days as multiple rounds of severe weather are possible. Make sure
you have multiple ways to receive warnings in the event that you are
placed under a tornado or severe thunderstorm watch.
Looking past Wednesday...Once the front clears the state, high
pressure will build into the area promoting calm and dry conditions
for a couple of days. The next chance of rain will return for the
weekend.
Average to above average temperatures are likely across much of the
state through the long term period as temperatures are expected to
get into the 70s and 80s. Overnight lows are expected to be in the
40s to 60s.
&&
.LZK Watches/Warnings/Advisories...NONE.
&&
$$
Aviation...57
Area Forecast Discussion
National Weather Service Memphis TN
944 PM CDT Mon Apr 11 2022
.UPDATE...
We`re continuing to monitor the beast-mode supercell moving east
along I-40, along with the accompanying smaller cells. Mesoscale
analysis indicates this storm will be moving into a more hostile
near-storm environment as it crosses the MS River, but it`s not
unusual for these storms to persist given their influence on the
surrounding conditions. RAP analysis indicates MLCAPE near 1000
J/kg nosing into the Memphis area though the increasing CIN does
suggest most new storms could have trouble rooting in the boundary
layer and may remain elevated. Effective bulk wind shear near 50
kts is more than sufficient to maintain organized updrafts while
the effective SRH near 400 m2/s2 will promote storm scale
rotation. Mid-level lapse rates remain steep south of I-40 at near
7.5 C/km which isn`t a surprise given the large hail the eastern
AR supercell has been producing. This looks to be the main show
with the greatest severe weather threat south of I-40 and west of
I-55. Given the weakened near-storm environment, a small Severe
Thunderstorm Watch was issued into the early morning hours.
Aside from the severe weather threat, there is also a potential
for localized heavy rainfall overnight. The CAMs have indicated
increasing coverage of subsevere convection overnight as the low-
level jet interacts with the outflow boundary from earlier storms.
Precipitable water has increased to near 1.5" and training storms
will have the potential for high rainfall rates. The LPMM from
the 12z HREF is pointing at pockets of 2-3" possible in the
vicinity of the I-40 corridor (some individual models are higher)
so we`ll be watching that closely as it could affect the Shelby
County area if this all comes together.
MJ
&&
.PREV DISCUSSION... /issued 339 PM CDT Mon Apr 11 2022/
DISCUSSION...
Currently...A nearly stationary front stretches from weak low
pressure near the ARKLATEX across NW AR-southern MO into the OH
Valley. Southerly winds south of the front continue to advect
moisture into the Mid-South which has helped to feed an MCS that
developed across NE AR a couple hours ago and is now slowly
working into parts of West TN. This activity will continue east
over the next couple of hours and should continue to weaken as it
moves into a less favorable airmass. Areas that the convection
moves over will pick up a quick inch of rain.
This evening into tonight...All eyes will be looking west into AR
late this afternoon into this evening. The airmass across SW/W AR
is becoming increasingly unstable and southerly winds will quickly
advect this unstable air into western portions of the forecast
area. A mid level shortwave with 60 kts winds at 500 mb will move
through the Mid MS Valley and the Ozarks this afternoon and
evening and help trigger storms along the stalled frontal boundary
in West AR. Latest CAMs and WoFS data indicate that these storms
will be supercellular initially. By this evening the airmass looks
able to maintain that storm mode at least into eastern AR. 18z
HRRR model soundings at 23z in eastern AR indicate SBCAPEs of 2000
j/kg+, 0-1km helicity values of 200 m2/s2 with decent low level
veering and mid level lapse rates of 8.1 c/km. STP values are
forecast to be above 2. Latest 12z HREF data are fairly aggressive
with UH tracks into east AR this evening and the latest WoFS
places potential supercells into or near east AR by 00/01z. Large
hail is a main threat with the steep mid level lapse rates and
given the storm mode a strong tornado is possible over east AR
and the MO Bootheel. Storm mode will trend toward clusters this
evening with the severe threat gradually waning with loss of
instability and upper support from the shortwave as activity moves
into west TN toward midnight. Threat may transition to heavy rain
and flash flooding according to some 12z CAMs. The persistent 850
mb LLJ may interact with any cold pools or outflow boundaries
from the evening`s convection to produce heavy rain. This could
persist well after midnight before breaking down by sunrise as the
LLJ weakens slightly. This heavy rain threat is not a sure thing
but if it does occur could produce a couple inches of rain
probably somewhere near the Memphis metro.
Tuesday...Could be a little leftover convection early in the
morning across the east, otherwise shortwave ridging will build
over the area during the day ahead of the main upper trough across
the western US. Should be breezy, warm and mostly dry across the
Mid-South with little to trigger convection. Highs will be around
80 with some peaks of sun.
Tuesday night...Next round of convection expected as a shortwave
lifts through the lower MS valley. This will trigger showers and
thunderstorms that will expand into the Mid-South during the
evening and mostly exit by Wednesday morning. There is decent
instability with MLCAPE around 500-1000 j/kg and 0-6km bulk shear
values over 45 kts associated with the shortwave. The 850 mb LLJ
will be increasing to 40-50 kts by midnight. This should be
adequate to support severe storms. Main threat will be damaging
winds and heavy rain with a couple tornadoes possible. Best
chances for severe weather will be across western sections of the
forecast area, mainly east AR.
Wednesday...Some morning convection should lift out early then
the airmass will destabilize once again ahead of a strongly
negatively titled trough and cold front. Parameter space indicates
the possibility for a significant severe weather event with
SBCAPES > 2000 j/kg and 0-1km helicity values above 300 m2/s2.
Expect a QLCS along the front with possibility of supercells and
the potential for strong tornadoes ahead of the front. NAMNEST and
FV3 are hinting at this. Timing looks like the afternoon across
eastern AR into the evening east of the MS River wrapping up
around midnight over eastern areas.
Thursday and Friday...Look quiet in the wake of the departing
system with weak high pressure and zonal flow aloft with
seasonable temps.
Weekend into Monday...Warm front lifts north from the Gulf Coast
and stalls over the area this weekend with chances for showers and
thunderstorms into early next week. Uncertainty is high.
SJM
&&
.AVIATION...
/00z TAFs/
Storms will move into the area and continue overnight tonight and
continue through early Tuesday. Expect shower development to be
confined to norheast Arkansas and west Tennessee. Short range
models show showers moving into the Memphis area around 07z, and
persist through 11z. Winds will mainly be from the south at 10 to
15 kts for most of the period with some llws this evening. Winds
will begin to gust by the end of the period.
SWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
859 PM MDT Mon Apr 11 2022
.UPDATE...
Issued at 847 PM MDT Mon Apr 11 2022
Red Flag Warning for this evening has expired. Quick look at
incoming 00z data suggests forecast is on track, with strongest
winds still progged late tonight/Tue morning over the southern
Sangres/srn I-25 corridor.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 326 PM MDT Mon Apr 11 2022
Key Messages:
1) Quick increases in speeds/gusts expected this evening and
tonight, with a High Wind Warning effect and now starting this
evening for the San Luis Valley, southeast mountains and adjacent
lower elevations, lower Chaffee and Teller.
2) High winds with light to moderate, occasionally heavy, snow
across the Continental Divide tonight.
Another day of high fire danger across southern Colorado, with many
places across southern Colorado gusting up to 35 to 45 mph and with
RH values right around 15 percent. Flow will continue to strengthen
this afternoon and as additional pressure falls are noted lee of the
mountains. This will support additional increases in winds and gusts
this afternoon, especially over Fremont and Pueblo counties where a
more relaxed gradient has supported lighter winds. With RH values
falling to the 10-15 range this afternoon into this evening, high
fire danger will continue over much of southern Colorado. No change
to the Red Flag Warning end time this evening, with RH values
expected to steadily improve through the mid evening time frame.
Did make some bigger changes to the High Wind headlines, by first
replacing the High Wind Watch with a High Wind Warning. Through
tonight, this includes the San Luis Valley, southeast mountains and
adjacent lower elevations, lower Chaffee, and Teller county. A
quicker arrival of the approaching system and strong flow aloft is
now expected, with most guidance really showing this trend. Did
bring up the start time for the San Luis Valley and Teller county
given this trend, while also increasing winds and gusts. Winds of 60-
70 mph will be possible tonight for the mountain valleys, with
highest gusts across the higher elevations quite possibly reaching
90 to 100 mph. Did debate starting the High Wind Warning for El Paso
county tonight, as flow is rapidly increasing overnight. Given most
of the county will decouple tonight, should not see widespread gusts
at or above 60 across El Paso. That being said, I do think
occasional gusts up to around 60 will be possible tonight for
locations in El Paso county immediately adjacent to the higher
terrain. Will continue to closely monitor though.
Increases in mountain snow expected this evening, and especially
later tonight across the Continental Divide. As flow strengthens and
large scale forcing increases ahead of an approaching trough, snow
intensity will increase late tonight. Moderate, occasionally heavy,
snow will be possible. Conditions will likely deteriorate tonight,
under this heavier snow and strengthening winds/gusts.
.LONG TERM...(Tuesday through Monday)
Issued at 326 PM MDT Mon Apr 11 2022
Long term AFD:
...Damaging winds along the southern I-25 corridor and a high
risk of critical fire weather conditions on Tuesday...
Key messages:
1) Critical fire weather concerns are going to be in place across
most of the plains tomorrow, and damaging high winds could be
possible, especially over Huerfano County and along the southern I-
25 corridor. Areas of blowing dust will more than likely occur along
the I-25 corridor.
2) The threat of critical fire weather will continue throughout the
week and weekend over areas of the plains and San Luis Valley,
becoming more spotty by Thursday through Friday, more widespread on
Saturday, and then more spotty again Sunday through Monday.
2) Higher elevation snow showers, heavy at times over the Central
Mountains, and lower elevation rain showers will continue to fill in
over the mountains, San Luis Valley, and over the adjacent plains of
the eastern mountains on Tuesday. Some thunder will be possible.
4) On Wednesday, the precipitation will spread across the plains and
transition over to snow after much colder air infiltrates over the
southeast Colorado. Temperatures will be much cooler and below the
seasonal average for highs. It will also be very windy.
5) From Thursday through Monday, there could be some snow showers
over the mountains, mainly the northern Continental Divide and
Rampart Range, and rain/snow over the Palmer Divide. There will be
more of a break in the precipitation on Friday.
6) On Sunday, some of the snow showers over the mountains look to
spread over the plains and be either rain or a rain/snow mix for the
higher elevations of the plains.
Detailed discussion:
Tuesday...
On Tuesday, as the major shortwave trough continues to deepen and
move over the region, with the associated low pressure center
ejecting out over the plains of northeastern Colorado. As a fairly
significant mid-level jet maxima moves over the area, coupled with
the tightening of the surface pressure gradient, very strong
southwesterly surface winds will develop over much of the region.
Some of the model guidance, even the NBM 4.0, has been showing
excessively strong wind gusts for certain locations, such as the
Walsenburg area in Huerfano County, where max wind gusts could reach
speeds above 100 mph. Due to this, a blend using the NBM 90th
percentile has been utilized to increase the winds, especially
emphasizing the increased flow over Huerfano County where most of
both the deterministic and ensembles have been pinging as the area
for strongest wind gusts. Even the HRRR is displaying a very strong
band of winds extending from the Wet Mountains and down along and
west of the southern I-25 corridor all the way to the New Mexico
border and Raton Pass with sustained winds above 50 mph by early
tomorrow morning. It cannot be stressed enough that with winds of
this strength, and from a southwesterly direction which will be
perpendicular at times to the I-25 corridor, that there could be
severe implications for high-profile vehicles due to these
potentially very strong crosswinds. Moreover, given the time that
the winds are expected to increase over areas of the I-25 corridor
during the early morning hours, there could be a greater number of
impacts to travel since traffic is expected to be heavier due to
rush hour.
With the nature of the very strong winds, along with very low
relative humidity values, as low as 10 percent over much of the
plains by later in the afternoon and throughout the early evening
hours, critical fire weather conditions will be likely across most
areas of the plains. It has been noted as well with a recent update
to the fuels that conditions are critical for zone 225, therefore
this will be added to the Red Flag Warning for tomorrow. These
conditions should subside by later in the evening as winds drop
below the threshold and RH recoveries improve to above 15 percent.
It is important to note that the forecast high wind speeds could
rapidly spread any fire initiation within a short period of time,
and also cause burning embers to be carried downwind over far
distances. For this reason, any hot spots that could appear need to
be carefully monitored.
Along with potentially damaging winds and the fire weather concerns
over most of the plains, winds will become strong enough that there
could also be areas of patchy or even widespread blowing dust
throughout the late morning and into the early evening hours,
especially along the southern I-25 corridor, where winds are
anticipated to be the strongest. This could result in temporarily
reduced visibilities down to a less than a mile for areas along the
southern I-25 corridor. The blowing dust could also spread downwind
across areas of the lower Arkansas River Valley and reduce
visibilities for places such as La Junta and Lamar. As winds weaken
later in the afternoon and by early evening, the impacts with
blowing dust will likely diminish. Up until this time, if you are in
one of these locations impacted by blowing dust and are sensitive to
allergens, it is advised to stay indoors as much as possible.
A third component with this low pressure system will be areas of
snow over the Central mountains, heavy at times, impacting travel
across locations such as the Wolf Creek Pass, where as much as a
foot of snow or more will be possible throughout the day on Tuesday.
The winds will also make travel conditions very treacherous over the
passes, with occasional whiteout conditions anticipated. The models
have been consistent with the Eastern San Juan Mountains receiving
the most total snowfall with this storm system, however, the
northern Continental Divide could also receive amounts as high as a
foot in certain locations along the western facing slopes. The
Sangre de Cristo Mountains will also receive some snowfall, although
there is not expected to be nearly as much snowfall due to the
orientation of this trough. The northern areas of this mountain
range will see as much as 4 inches of snow, but the bigger impact
for the Sangre de Cristo Mountains will be the winds, which some
model guidance suggests that gusts could reach in excess of 115 mph
across the tops of some of the highest peaks. It is also possible to
see some more convective showers with period of heavy snow and
thunder possible. NAM is showing highest CAPE values of around 150
to 200 J/kg tomorrow afternoon over the southern Central Mountains,
so this area would be the most likely at seeing some thundersnow.
Snow will continue to increase over the mountains by later in the
evening, yet due to the orientation of this trough, the plains and
San Luis Valley/Upper Arkansas River Valley should remain relatively
dry.
The downsloping winds will allow temperatures to become quite warm
over the eastern plains, with high temperatures getting above the 80
degree mark in the lower Arkansas River Valley. Depending on how
much mixing is occurring within the PBL over the I-25 corridor will
depend on how much it will adiabatically warm at the surface,
therefore high temperatures could vary either above or below of what
the NBM guidance is displaying for high temperatures across these
areas. With fire weather conditions expected, the most significant
determining factor of this could be how much of a dewpoint
depression there is and how low relative humidity values get by mid
afternoon. Temperatures over the higher mountain valleys will not
get quite as warm, and therefore the dewpoint spread will allow for
RH values to be above the threshold, which is why fire weather
conditions are not anticipated for the San Luis Valley or the upper
Arkansas River Valley. Passage of a cold front with southwesterly
winds backing to a northwesterly direction right around midnight
will allow temperatures to drop off rather quickly. Lows will drop
into the 20s over the plains, to the teens in the upper mountain
valleys, and down to the single digits for high country.
Wednesday...
The low pressure system will continue to move east but the
northwesterly winds, along with some residual moisture on the
backside of the system, will allow more much colder air advection
and an increasing chance of precipitation over the plains. This
precip may initially begin as rain, but then transition will to snow
over most areas of the plains throughout the early morning hours.
Winds will also increase out of the west over the San Luis Valley,
and northwest over the plains throughout the day. With drier air
infiltrating in behind the system as subsidence occurs, there will
be areas of widespread fire weather concerns possible over most
areas of the plains and the San Luis Valley by later in the
afternoon and throughout the early evening hours. All precip should
come to an end by later in the evening over most of the CWA,
although there could still be a few lingering snow showers still
occurring over the northern Continental Divide. Much colder
temperatures will be felt for afternoon highs on Wednesday, and
below the seasonal average for much of the CWA.
Thursday through Monday...
This period in the forecast has continued to be where the
deterministic models have differed quite a bit with respect to some
shortwaves well upstream, and even the GEFS and EPS ensemble members
have also continued to display a wider range of variability,
alluding to higher uncertainty. The NBM shows that snow showers
could continue to be possible, especially over the northern
Continental Divide and Rampart Range, from Thursday though Saturday
due to a generally mid level northwesterly flow, and some of this
moisture could move out over the plains on Sunday. Friday looks to
be the best chance for a break in any precipitation over the CWA as
some weak ridging occurs over the region. There could also be spotty
critical fire weather concerns for each day through Sunday as well
through due to downsloping winds. Temperatures now look to continue
to warm going into the weekend over the plains with the downsloping
winds as well, with a cooldown on Monday after a cold front moves
through. -Stewey
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 326 PM MDT Mon Apr 11 2022
Blowing dust is degrading visibility at KALS. MVFR conditions with
visibility down to 2SM are expected there until 03Z.
VFR conditions are expected at KCOS, KPUB, and KALS for the
remainder of the TAF period, however, dangerous winds and low-level
wind shear are also expected to increase at all three sites.
Starting after 22Z this evening, winds will begin to gust up to 40KT
in our mountains and in the San Luis Valley, reaching 50+kt by 06Z
late tonight. High winds will make their way into the eastern plains
later Tuesday morning, with the worst of them looking to impact KCOS
and KPUB between 15Z-21Z on Tuesday afternoon. Guidance shows gusts
in our region easily reaching 60kt in places, with possibilities
of seeing 80kt gusts increasing with newer model runs, especially
at KPUB and KALS. Confidence isn`t high enough yet to include
winds over 50kt at any of our TAF sites, but new guidance is being
carefully incorporated. Winds are not expected to ease until
Tuesday evening after sunset.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 9 AM to 8 PM MDT Tuesday for COZ089-
093>099.
Red Flag Warning from 11 AM to 8 PM MDT Tuesday for COZ221-222-
224>237.
Winter Weather Advisory from midnight tonight to noon MDT
Wednesday for COZ059-061-065-067.
High Wind Warning until 8 PM MDT Tuesday for COZ069>075-078>080-
087.
Winter Weather Advisory until noon MDT Wednesday for COZ058.
High Wind Warning from midnight tonight to 8 PM MDT Tuesday for
COZ076-077-081>083.
High Wind Warning from 6 AM to 8 PM MDT Tuesday for COZ084>086-
088.
Winter Storm Warning until noon MDT Wednesday for COZ060-066-068.
High Wind Warning from midnight tonight to 6 PM MDT Tuesday for
COZ062.
&&
$$
UPDATE...PETERSEN
SHORT TERM...RODRIGUEZ
LONG TERM...STEWARD
AVIATION...EHR/RODRIGUEZ
Area Forecast Discussion
National Weather Service Blacksburg VA
803 PM EDT Mon Apr 11 2022
.SYNOPSIS...
High pressure pushes off the coast today with a warm front lifting
north this afternoon. A cold front approaches the mountains tonight
bringing isolated shower chances Tuesday. The front retreats north
Wednesday before a more robust cold front approaches Thursday with
scattered showers and storms. Temperatures will be above average
throughout the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 700 PM EDT Monday...
Overall, the afternoon forecast package remains in good shape,
however went with a modest adjustment in temperatures through
the evening given the increased cloud cover passing across the
lower Mid-Atlantic helping to slow the rate of evening cooling.
Rapid update weather forecast models continue to indicate
light, widely scattered showers passing across the mountains
this evening and through the night, with perhaps a few hundreds
of an inch accumulation in spots. Overnight lows will range from
the upper 40s/low 50s for the mountains, to the mid 50s for
much of the Piedmont.
As of 252 PM EDT Monday...
Warm temperatures and increasing clouds this afternoon with
isolated shower chances over the mountains Tuesday morning...
High pressure continues offshore this afternoon and evening
while a relatively moisture-starved warm frontal boundary lifts
through. Winds have since changed to more of a south and
southwesterly direction hence the bump in temperature and a
return to Spring across much of the region. Temperatures today
will run anywhere between 20 to 40 degrees warmer from where we
were this past weekend. Highs will range from the upper 60s and
low 70s over the mountains to around 80 across the Piedmont.
These values are actually 5-10 degrees above average for this
time of year and look to mark a trend of warmer conditions for
the remainder of the workweek ahead.
Clouds will continue to increase this afternoon especially in
areas along and west of the Blue Ridge as moisture builds ahead
of a cold front that will push into the region from the Ohio
River Valley. The front looks to approach the region late
tonight into Tuesday morning providing increased shower chances
for areas along and west of the Blue Ridge Parkway. Some
uncertainty remains in how far south the front will sag since it
will remain fairly elongated and displaced from the main upper
level energy source. 12z hi-res guidance seems to agree with
this notion in a front that sags over our western mountains
before retreating back to the north late Tuesday afternoon and
early evening. Even with that said, will allow for an isolated
shower chance or two along and east of the Blue Ridge Parkway
although confidence is fairly low. Rain chances will range
between 10 to 20 percent in these locations compared 30 to 50
percent chances west of the Blue Ridge. Have left a mention of
thunder out since instability still appears to be weak when the
bulk of the system comes through.
High temperatures Tuesday will range from the mid to upper 60s over
the mountains under extra cloud cover compared to near 80 further
east where a bit more sunshine looks to poke through.
Confidence is moderate to high in the near term period. Some
uncertainty in regards to how far south our cold front pushes.
Leaning toward a mix of the 12z HRRR and ARW solutions compared to
the NAMnest which is a bit more agressive on precipitation Tuesday
morning into Tuesday afternoon.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 1249 PM EDT Monday...
Front to bring shower/few thunderstorms Thursday. Otherwise warm
this period.
During this period a warm front lifts north into the mid-Atlantic
states Tuesday night-Wednesday as southwest flow aloft increases and
5h heights and 8h temps increase. Could see a few showers in the
mountains Tue night-Wednesday with the warm front, but mainly dry.
The main upper low will be well away from the actual cold front over
southwest Ontario into the upper Great Lakes.
Models favor a line of showers/few storms moving across Thursday-
Thursday night but actual rainfall amounts should be limited and
severe threat is low due to lack of dynamics but still instability
should be around due heating in the east for some thunderstorms.
Timing of showers places it across the mountains Thursday morning
and in the piedmont into the afternoon.
Front may slow down as another wave appears to form along it across
the southeast Thursday night, so kept low chance pops in the
piedmont into the overnight.
Warm temperatures even for lows Tuesday-Wednesday into early
Thursday, then somewhat cooler Thu night.
Wednesday appears to be the warmest day with upper 70s to lower 80s
east of the mountains to 70s west. Thursday will be cooler in the
mountains based on timing for showers/clouds, with mid 60s to around
70, while the piedmont warms up into the upper 70s.
Lows Tuesday night will be in the 50s, then warmer Wed night
especially the piedmont with lower 60s, while mid to upper 50s occur
in the mountains.
Forecast confidence is above average on temperatures/winds and
slightly above average on precip chances.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 100 PM EDT Monday...
Dry to start the weekend, then showery with seasonal temperatures to
close the weekend out.
Deep upper low over Ontario Friday heads slowly east into Quebec
over the weekend and this is when model difference arise. The GFS
flattens the flow once this trough moves across with a weaker
upstream shortwave moving across the northern Plains Sunday. The
ECMWF is further south with the departing upper low and shows more
amplified flow across the upper MS Valley into the plains allowing
more return flow to set up into the TB Valley and central
Appalachians. The Canadian is closer to the GFS but has a southern
stream system possibly bringing rain in Sunday. As far as precip
model blend and ensembles show a weak front stalled across the area
this weekend but again moisture differs, so going lower pops into
Saturday, the settling on chance pops Sunday-Monday despite some
models showing at least a 6-12 hour window of favorable precip, but
timing and model difference lead to a lower confidence forecast.
Early next week the ECMWF closes off upper low over the western Ohio
Valley and is an outlier with other models and the ensembles, though
a deeper trough per ensembles could allow for a low to cutoff. For
now the GFS/Canadian offer reasonable solution of shower chances
into Monday and not as cool as the Euro.
Temperatures cool slightly compared to early-midweek values but
still about 5-10 degrees above normal until Sunday before we cool
back closer to normal.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 800 PM EDT Monday...
Cloud bases will continue to lower through the night, with
spotty occasional showers in the forecast.
High clouds continue to build across the lower Mid-Atlantic
this evening, with bases continually lowering as they progress
eastward. Radar also indicates a few returns of light shower
activity across the mountains, though some of this is likely in
the form of sprinkles barely reaching the ground. Wind speeds
for much of the area have fallen below 10 knots, though
occasional gusts across the mountains are still reaching as high
as 25 knots.
Through the night, expect mainly VFR conditions through around
daybreak, though cloud bases will continue to lower as moisture
builds northward across the region ahead of an approaching cold
front. Spotty and light rain showers will continue to pass
across mainly the mountains, but these should have minimal
impact on flying conditions. Expect winds out of the west-
southwest below 10 knots, though mountain ridges can expect
localized gusts as high as 25 knots.
Though the cold front is not expected to enter the forecast
region on Tuesday, it will remain close enough - stretching
across central West Virginia through northern Virginia by
sunset - to maintain occasional and spotty shower activity
through the day. Ceilings are expected to fluctuate between high
MVFR and low VFR across the mountains, and remain low VFR
across the Piedmont.
No thunderstorms are expected during the valid TAF period.
Confidence is moderate to high in the TAF period.
Extended Discussion...
Will be in and out of sub-VFR conditions with shower and storm
chances, mainly during the afternoon hours Wednesday through
Thursday.
Chances at most TAF sites are hit and miss, with higher chances at
LWB and BLF. Ceilings will also bounce around quite a bit, but in
general expect areas of MVFR in -SHRA/-TSRA with LAMP probability
guidance indicated LWB and BLF are the most likely candidates for
sub-VFR Wednesday and Thursday. In addition, it looks like ceilings
should stay above IFR through Wednesday.
Winds gradually turn more southerly by Wednesday, with gusts around
15-20 kts. West winds develop Thursday behind a cold frontal passage
with gusty winds once again. High pressure builds in Friday keeping
conditions VFR.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...ET
NEAR TERM...ET/NF
SHORT TERM...WP
LONG TERM...WP
AVIATION...ET/NF
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 257 PM CDT Mon Apr 11 2022
Forecast Key Points:
- A Low-Predictability, High-Impact Severe Weather Setup Tomorrow
Afternoon and Evening
- Extreme Fire Danger Expected Across North Central KS Tuesday
- Gusty South Winds Up To 50 MPH Expected Tuesday Afternoon into the
Overnight
- Quieter and Cooler Weather Beyond Tuesday
As of 230 PM Monday afternoon, broad cyclonic midlevel flow was
present across the central and western US with a shortwave trough
digging into the Intermountain West. The surface trough axis, which
moved through the area yesterday has pushed into portions of north
TX through south central MO. This trough axis has become stationary
due the midlevel shortwave advancing well-northeast. The approaching
western midlevel trough will gradually advance the trough axis back
north overnight as a warm front. As the front lifts across the
forecast area, a surge in low-level moisture is anticipated. By
Tuesday morning, most of the area will likely be covered with low
stratus and increasing southerly winds. By midday, south winds are
forecast to increase to 20-30 MPH with gusts up to 50 MPH. As a
result, have issued a Wind Advisory from Noon Tuesday through 1 AM
Wednesday.
Transitioning into the afternoon hours Tuesday, a low-predictability,
high-impact severe weather setup is expected to develop. A sharp
dryline is forecast to mix into portions of central and north
central KS by mid to late afternoon. Extreme fire danger is expected
west of the dryline. Please refer to the fire weather section below
for additional details. Translating back into the warm section, 3
separate areas could provide focal points for thunderstorm
development, additional details immediately below.
Beginning with Area #1 (east central/northeast KS):
An expansive stratus deck is expected for the area through the
morning and into the afternoon. Gradual clearing is expected from
west to east with boundary layer mixing deepens from west to east.
Multiple deterministic model guidance, including the GFS, NAM, HRRR,
Fv3, and HRRR suggest a differential mixing boundary will emerge
somewhere in the vicinity of Highway 75 during the mid to late
afternoon hours Tuesday. This boundary could provide sufficient
convergence for convective initation after 21Z. The background
environment within the entire warm sector is very conducive for
supercells capable of very large hail and tornadoes. Any discrete
storm after 7 PM Tuesday will see the threat for a strong tornado
increase substantially as effective SRH values exceed 400 m2/s2.
Again, this is a very conditional probability and storms may not
develop at all.
Area #2 (central and north central KS):
The aforementioned dryline is forecast to mix into portions of
central and north central KS by mid to late afternoon. Like area #1,
the background environment will be very conducive for supercells,
should a storm develop. Strong surface heating will gradually erode
the capping inversion by late afternoon. The main potential failure
point for convective initiation is the lack of any strong mid/upper
level forcing for ascent. Model guidance suggests modest midlevel
height falls will overspread the dryline region by late afternoon.
These modest height falls combined with weak surface convergence
could allow for a few storms to develop. The same scenario would
play out for any discrete storm after 7 PM as in area
#1.
Area #3 (eventually the entire forecast area):
Confidence is highest for convective initiation in this zone. The
main midlevel trough will eject into the Plains after 7 PM,
overspreading the cold front from eastern NE through south central
KS. This increasing midlevel ascent should foster a rapid increase
in linear convection after 10 PM. Forecast guidance depicts the
linear convection will build southward and move east into portions
of north central KS by 1 AM Wednesday. This line may be severe and
pose mainly a damaging wind threat.
Beyond Tuesday, a cooler and quieter weather pattern is forecast to
overspread the region for the remainder of the period. Wednesday
afternoon will have to be monitored for increased fire danger as low
humidity and gusty winds may overlap across north central KS.
Otherwise, a low-amplitude shortwave is progged to eject into the
Plains over the weekend, increasing rain chances for Sunday into
Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 649 PM CDT Mon Apr 11 2022
Surging low level moisture northward aft 09Z will likely bring IFR
stratus to terminals, gradually improving back to VFR around 17Z.
Low level jet increases to just under 60 kts at 2 kft from the
south between 09Z and 12Z while sfc winds veer to the south and
become gusty by this period. LLWS may be marginal initially around
09Z, however with the increasing sfc speeds and wind gusts,
confidence is not high enough for mention. Also left out mention
of drizzle, albeit possible given the low level lift present at
TOP/FOE on forecast soundings.
&&
.FIRE WEATHER...
Issued at 257 PM CDT Mon Apr 11 2022
Extreme fire weather conditions are expected Tuesday afternoon and
evening west of a sharp dry line. Latest indications suggest the dry
line will setup near/just east of Highway 81 by late Tuesday
afternoon. Relative humidity values will rapidly fall to 10-20
percent with southwest winds gusting up to 50 MPH. Per the latest
update from Kansas State Forest Service, fuel loads are at historic
levels yielding very erratic fire behavior. A drastic wind shift to
the northwest is expected between 7-10 PM across north central KS.
Relative humidity values should gradually increase through the
night, although northwest winds will gust above 25 MPH through much
of the night.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from noon Tuesday to 1 AM CDT Wednesday for
KSZ008>012-020>024-026-034>040-054>056-058-059.
Red Flag Warning from noon to 9 PM CDT Tuesday for KSZ008-020-
034.
&&
$$
DISCUSSION...Baerg
AVIATION...22
FIRE WEATHER...Baerg