Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/18/24
Area Forecast Discussion
National Weather Service Burlington VT
1023 PM EDT Wed Apr 17 2024
.SYNOPSIS...
A weakening area of surface low pressure moving into the Great Lakes
region combined with embedded shortwave energy aloft will bring a
period of light rain to the forecast area late tonight through
Thursday. Dry conditions follow for Friday morning, but a cold front
passage in the afternoon and evening will bring an additional round
of light rain. Mostly dry conditions and seasonally cool
temperatures are expected for the weekend.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 1020 PM EDT Wednesday...
Forecast remains very much on track. Only made minor changes to
the hourly temperatures and PoPs as SPC RAP mesoanalysis shows
a dry air mass remains in place across North Country.
Temperatures have responded to rather effective radiational
cooling region wide despite the thin mid and high clouds. Given
that dew points are in the upper 20s to low 30s, it is possible
that snow is mixed in with the rain showers down to 1000 ft
elevation during precipitation onset during the overnight hours thanks
to wet bulb cooling. However, no accumulations or travel
impacts are expected given the warm road temperatures and
overall light precipitation rates.
PREVIOUS DISCUSSION...
Overall the forecast for tonight through Thursday night remains
on track with a weakening are of surface low pressure tracking
into the Great Lakes region being the main feature of interest
for weather across the North Country and Vermont. Shortwave
energy ejecting out of the parent mid/upper level trough on
southwest flow will provide the support for showers to develop
late tonight through Thursday as a ribbon of enhanced low to mid
level moisture moves in on the nose of a modest 925-850mb jet.
Ahead of the precipitation, southeasterly winds look more robust
compared to the previous forecast with good mixing ahead of the
precipitation and 925mb winds in the favored downslope prone
regions topping out around 45kts. Think areas along the western
slopes of the Adirondacks and Green Mountains will see gusts in
excess of 35mph for a short period after midnight through midday
Thursday before the areal coverage of showers increases and the
low levels stabilize. Showers may linger into the first half of
Thursday night as well with low clouds and moisture potentially
supporting some areas of drizzle through the night as well.
Overall the basin average QPF will be light though, with
generally 0.2" or less across Vermont and up to a third of an
inch possible across northern New York. Min temps tonight and
Thursday night will be on the mild side of normal in the upper
30s to mid 40s, and highs won`t be much warmer on Thursday in
the mid 40s to low 50s.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 310 PM EDT Wednesday...As we transition further into Spring,
days like Friday will become increasingly common. Slated for Friday
will be a one-two combo with a prefrontal trough during the
afternoon and the actual front coming through after sunset. The
highest chances for showers will be Friday afternoon, but most
forcing will come from isentropic upglide. Overall, the better
dynamics are to our north, and the frontal boundary is diffuse.
Precipitation amounts will be at or less than 0.10" favoring
northern New York and the northern Greens. Breezy south to southwest
flow will yield wind gusts of 15 to 25 mph, especially in the
northern Champlain Valley and northern slopes of the Adirondacks.
High temperatures will mainly be in the 50s, with a few spot 60s in
warmer locales within the St. Lawrence and northern Champlain
Valley. Cold air before the front could bring a few summit snow
showers as temperatures sink into upper 30s to lower 40s at low
elevations, 30s in the Adirondack wilderness, and Mt. Marcy and
Whiteface into the upper 20s.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 310 PM EDT Wednesday...There are several vigorous shortwave
troughs that will traverse the region over the weekend into the new
week. However, none of them really tap into a tropical moisture
feed. The strongest one will swing through on Saturday. Although
surface moisture will be decreasing from a recent frontal passage
and surface pressures are rising, the vorticity advection with the
trough is quite strong and there will be steep low level lapse rates
with up to 100 J/kg of CAPE. It is difficult to say whether
precipitation can reach the ground. Forecast soundings depict very
dry near surface conditions. What this may do is produce virga that
also create gusty winds as the steep low-level lapse rates aid in
the acceleration of downdrafts in convective activity. For now, the
forecast depicts the highest precipitation chances along the
international border where the shortwave tracks and keeps conditions
dry south with wind gusts generally 25 to 30 mph, locally up to 35
mph.
The next shortwave trough moves in almost immediately behind the
previous system, racing through Saturday night. Ultimately, this
system will likely have too little moisture and will reinforce cool
air that should keep the region around seasonal norms. The next
upper trough will descend over Quebec Province late Sunday evening
into Monday, but the front is so diffuse and it will again be
moisture starved. Upper level troughiness gets briefly interrupted
by a weak ridge and south to southwest flow to produce some warmer
temperatures. However, by late next Tuesday evening into next
Wednesday, there is another trough. This one should have some more
moisture with it and have a larger impact on sensible weather
conditions with shower activity sliding in for the middle of next
week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Through 00Z Friday...VFR conditions are expected to prevail for
the next 12 hours or so across the region. A slowly approaching
cold front will battle dry air as it moves into the forecast
area. MSS and SLK will be the first to experience some MVFR
conditions, though downsloping could provide SLK with some extra
hours of VFR before ceilings drop. Rain showers from the cold
front will be fairly light with limited precipitable water,
likely 5+ miles vis. After MVFR ceilings and occasional vis
reach the NY sites, this will progress northeastward into VT
sites slowly. Winds generally north/northeasterly will be
increasing around 06-12Z Thursday with gusts 15-30 knots and
direction turning more southeasterly. RUT has the potential to
see some low level wind shear around 11-18Z Thursday as well. Of
all sites, MSS is most likely to have IFR ceilings develop 15Z
Thursday onward, but confidence is not high at this time, so
this is not in the TAF.
Outlook...
Thursday Night: Mainly MVFR, with areas VFR possible. Chance
SHRA.
Friday: Mainly VFR, with local MVFR possible. Chance SHRA.
Friday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Saturday: VFR. Chance SHRA.
Saturday Night: VFR. NO SIG WX.
Sunday: Mainly VFR, with areas MVFR possible. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Lahiff
NEAR TERM...Chai/Lahiff
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Storm
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
640 PM CDT Wed Apr 17 2024
.KEY MESSAGES...
- Thunderstorms Possible Late Tonight Early Thursday
- A Few Storms Late Tonight / Early Thursday May Be Severe
- Cooler Temperatures Remainder of Week
&&
.DISCUSSION...
Issued at 405 PM CDT Wed Apr 17 2024
Broad troughing over the Northern Rockies has been promoting dCVA
across much of the High Plains and Central Plains this afternoon,
allowing a surface cyclone to deepen across the OK/TX Panhandle
Region. This system has started to shift northeastward, and has
allowed lower level winds to shift from the southwest. Last night`s
cold front and subsidence behind it helped keep skies mostly clear
across the region, allowing temperatures to jump back into the upper
70s and lower 80s across the area. There has been increasing ascent
along the 305K isentrope but with little moisture to work with thus
far no clouds or stratiform rain have been able to develop. As of
this afternoon, dewpoints across the region are still only in the
upper 40s. However, the low-level flow shift in response to the
surface cyclone developing should help to bring in an airmass from
Oklahoma and other portions of the southern Plains where dewpoints
have been in the mid 60s. Once this moisture reaches our area,
precipitation chances will start to increase. Current synoptic scale
deterministic guidance has the trough lifting back into Canada with
strongest vorticity heading back northward, but continues to show a
signal a for few vort maxes to eject southeastward across the
Central Plains into the Lower Missouri River Valley. This will be
enough to provide subtle H5 height falls and should help to increase
mid-level flow and overall deep layer shear. As the cyclone
continues along with this area of subtle H5 height falls, the low-
level jet remains progged to strengthen, with some guidance
suggesting a magnitude as high as 45-50kts. Convergence along this
and the trailing cold front late this evening will provide and
opportunity for convection initiation. Since this morning, the HRRR
has be depicting a few clusters of storms developing in eastern
Kansas after 04z then moving northeast into our forecast area
between 05-08z. The system then stalls out for a few hours, but then
another short-wave from the north sinks further south sending
another vort max, which will push the system and cold front back
toward the southeast. By this point there will likely be sufficient
moisture transport into the lower Missouri River Valley sending
dewpoints in to the mid 50s, with lower 60s in our far southern
counties. Convergence once again increases and is expected to result
in more convection initiation. CAMs the past few cycles have been
pointing toward a line of cells developing along this forcing,
pushing from northwest Missouri across a large portion of the state
through the morning and early afternoon. Model soundings across the
warm sector show a moderately strong temperature inversion above the
boundary layer which will limit surface based parcels. However,
lapse rates between 850mb-600mb will be just a tad under 8.0 C/km,
cloud layer shear around 63 kts and effective-bulk wind difference
around 40 kts. MUCAPE values are currently progged between 750-1000
J/kg. With the low-level jet present, the shear and instability
should be supportive of organized updrafts resulting in stronger
thunderstorm activity. A few severe storms could also be possible.
The main threat with storms through Thursday morning would be hail
at least 1" in diameter. Current thinking is that tornado threat
will be extremely limited given that the lowest portion of the
curved hodograph will not be realized with inflow bases above 1km
for these storms. Typically with elevated convection damaging wind
is not a primary concern, but there have been a few CAMs pointing to
potential of gravity wave structure that could help wind gusts punch
through a statically stable boundary layer. This could produce winds
to around 60 MPH especially with stronger momentum around the 700mb
layer. However there is some uncertainty with this, therefore will
consider hail the primary concern with stronger storms Thursday
morning. Overall confidence in precipitation along the front is
fairly high, with most ensemble suites well over 90 percent for at
least 0.10 inches of rain across most of the forecast area. GEFS
probabilities for at least 0.50 inches are 50 to 60 percent for a
corridor between Hwy. 36 to just south of Interstate 70.
Cold front is progged to push through the area after 20z tomorrow,
with moisture around the backside helping to keep stratiform cloud
cover in place. Most of the accumulating precipitation should be
ending, though a few lingering showers may still be possible,
especially if the front stalls longer earlier Thursday morning. Once
the front moves through, expecting a few days of cooler temperatures
generally in the lower to mid 60s across the area. The synoptic
pattern will generally be zonal with minimal areas of vorticity
advection which should limit most of the precipitation chances.
Perhaps if there is subtle wobble southward from the H5 closed-low
over Canada a light shower could be squeezed out over the weekend.
However amongst NBM members and other ensemble suites, probabilities
for measurable rain through the weekend remains below 20 percent for
our counties and under 10 percent for a threshold of 0.10 inches.
Mid-level ridging over the Central Plains will help promote
subsidence and anticyclone development across our area through most
of the weekend. For next week, ridging over the western CONUS is
progged to amplify which should start to promote southwesterly flow
back across the Central CONUS and helping to bump temperatures back
up across the area. Inner-quartile spreads amongst NBM members for
temperatures through next week are a bit larger, which would
indicate there is some uncertainty with how a few of the short-waves
across Canada behave. It may be possible if one of those that sink
further south, the ridge does not amplify as much and keeps our
temperatures cooler. This may even be able to provide rain chances
across our northern counties.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 637 PM CDT Wed Apr 17 2024
Currently VFR conditions at all terminals with light and
variable winds. Scattered showers and thunderstorms may impact
the terminals in the 5z to 9z window this evening/early
overnight. These storms could pose a hail threat. Another
round of storms is likely in the 10z to 14z time frame, with
showers lingering behind the storms for a few hours before
precipitation finally clears east of the terminals by early
afternoon. IFR/MVFR CIGs are likely for much of tomorrow morning
and afternoon. Northerly winds should increase behind the front
tomorrow afternoon with gusts up to 25 knots.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.
&&
$$
DISCUSSION...Krull
AVIATION...BMW
Area Forecast Discussion
National Weather Service North Platte NE
742 PM CDT Wed Apr 17 2024
.KEY MESSAGES...
*Precipitation chances today and tonight
*Strong winds this evening into the overnight
*Cooler through the first part of the weekend
*Another chance for rain/snow Thu. night through Sat. morning
&&
.UPDATE...
Issued at 737 PM CDT Wed Apr 17 2024
A forecast update is in place to increase snow probabilities
across the Sandhills into the southern Panhandle through mid-
morning Thursday.
Latest observations and NDOT cameras depict snow in progress
across the Pine Ridge. While most if not all accumulations
should remain to grassy surfaces, some of this activity
overnight may be high enough intensity to lead to briefly slushy
accumulations on area roads. Latest RAP guidance shows
increasing h7 fgen as the main source of lift. With such strong
lift, dynamical cooling is allowing for this fairly early
transition to snow even with air temperatures remaining above
freezing. Overall, believe overnight lows will struggle to fall
much below freezing and with the quick warm up Thursday any
lingering snow will be quick to melt away.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 340 PM CDT Wed Apr 17 2024
There are a couple of concerns in the short term. The
first being the potential for showers and thunderstorms this
afternoon and evening, and strong winds this evening into the
overnight. Precipitation chances will increase late this afternoon
across western Nebraska with the approaching front. There is the
potential for thunderstorm development across the southern Sandhills
into southwest Nebraska in the early evening and could event
potentially see an isolated threat for a severe storm, which would
mainly be for damaging wind gust, but could also see some small hail
with an outside chance of hail up to 1". Storms look to be elevated
in nature, but soundings do suggest there could be an environment
favorable for downburst or strong outflow within the strongest
storms. There will also be the chance for more moderate rainfall
across portions of north central Nebraska, extending back into
the central Sandhills, generally along and east of HWY 83.
Rainfall amount of 0.25 to 0.50" may be possible.
As for snowfall potential, did decrease precipitation chances
across the northern Sandhills after midnight across the
northwest Sandhills, which looks to confine most of the
precipitation across the northwest Sandhills to rain as
temperatures will generally main above freezing during the best
chance for precipitation, however a brief period of a rain/snow
mix can`t be ruled out, but do not expect any snowfall
accumulations.
The next concern is the winds this evening into tonight, strong
winds will move into the area behind the frontal boundary. Some
bufkit soundings are hinting there could be some good deep
layer mixing just ahead of the frontal push and could
potentially tap into some strong winds of 40 to 50kts that could
bring an isolated 50 mph wind gust or stronger to the sfc,
mainly across southwest Nebraska, generally south of I- 80, in
the early evening hours. As the front passes more widespread
stronger winds will be expected across southwest, north central
and portions of the central and southern Sandhills starting in
the mid evening hours, through the overnight. Probabilistic
models continue to increase winds during this time period with
the last several runs, thus forecaster confidence has increased
in seeing widespread wind gust of 30 to 40 mph, so have bumped
winds up to better account for this.
Cooler temperatures tonight and Thursday, weak CAA behind the
frontal boundary will bring in lows tonight in the upper 20s to mid
30s and keep highs on Thursday generally in the upper 40s to low
50s. Coldest temperatures will generally be across the northern
Sandhills.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 340 PM CDT Wed Apr 17 2024
The weather pattern will remain active to end the week
into the weekend with a couple of disturbances affecting the area.
After a brief lull in precipitation for Thursday, chances increase
into Thursday evening into Friday. A secondary push of colder air
will move in late Thursday and will see a better chance for a
rain/snow mix across the northwest Sandhills early Friday morning.
Although accumulations still look to be marginal, a light dusting
may be possible. For the rest of the area, precipitation will mainly
be in the form of light rain showers throughout the day, mainly for
areas west of HWY 281. At this time rainfall amounts Friday into
Saturday look to be light, generally around a tenth of an inch or
less.
A weak upper level ridge builds in across the west and will bring a
return to warmer temperatures with highs bouncing back into the
upper 50s to low 60s for Sunday and even some upper 60s to low 70s
by Monday.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 701 PM CDT Wed Apr 17 2024
An area of MVFR ceilings will move southeastward this evening
and overnight behind a cold front. In addition to the lower
ceilings, gusty winds will develop, especially across portions
of western into southwest Nebraska. Showers and a few
thunderstorms can also be expected. Wet snow may briefly develop
across portions of the Sandhills late this evening and
overnight. Conditions improve during the morning hours Thursday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...NMJ
SHORT TERM...Gomez
LONG TERM...Gomez
AVIATION...Taylor
Area Forecast Discussion
National Weather Service Louisville KY
925 PM EDT Wed Apr 17 2024
.KEY MESSAGES...
* Strong to severe storms possible Thursday evening and overnight.
* Much cooler weather this weekend.
&&
.UPDATE...
Issued at 920 PM EDT Wed Apr 17 2024
Cold front draped across Kentucky is most evident as a dewpoint
gradient, with dewpoint values in the lower/mid 60s to the south,
but dropping into the upper 40s behind the front. Winds are actually
slacking off fairly quickly behind the front, and with clear skies
this will allow a noticeably cooler night compared to last night.
Min temp forecast in the 50s is pretty well on track, so no changes
planned at this time.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 327 PM EDT Wed Apr 17 2024
Looking at satellite imagery and wind observations, the cold front,
stretching from the low pressure system over the western Great
Lakes, can be seen stretching northeast to southwest through the
CWA. As this front continues to the east this afternoon and evening,
southern Indiana and central Kentucky will see gusty winds veer
towards the west. Dry air in the 850 mb level is killing any chance
for convective weather. This is a good thing given the strong shear
in the region. This dry layer is also helping to lift and clear
skies.
Tonight, zonal flow will push a ridge of surface high pressure east
into the Lower Ohio Valley. This will cause winds to become more
variable and quickly ease as a low level inversion develops. Across
far southern Kentucky, light warm air advection along with the
possibility of some late night to early morning sky cover will lead
to low temperatures only dropping into the low 60s. Lows are
expected to taper cooler to the north with our northern communities
falling into the low 50s.
Tomorrow, as the surface high over eastern Tennessee gets pushed to
the east and a surface low, along an approaching cold front, over
Oklahoma gets pushed east, it will begin to influence the CWA. Winds
will veer from mostly the east in the morning to the south by the
afternoon. They will also increase to 10-15 mph west of Interstate
65. Gusts could reach to around 20 mph. East of 65, most areas will
see 5-10 mph winds. Skies will be mostly sunny across the CWA, but
as the surface low quickly moves from Oklahoma to Illinois during
the day, increasing clouds will begin to move into the our southern
Indiana counties from the northwest. The added sunshine and warm air
advection will help lift high temperatures into the low to mid 80s.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 327 PM EDT Wed Apr 17 2024
Thursday Night through Friday Night...
A period of active weather for portions of the region looks likely
for Thursday night as a weakening surface low pressure system tracks
from the Mid-MS Valley northeastward into central IN/OH with a
trailing cold front sagging southward through the lower Ohio Valley
overnight. Convection is expected to be well developed in the form
of a linear MCS prior to the start of the forecast period. This MCS
is likely to extend from central IN southwestward through southern
IL/eastern MO/western KY. A well mixed boundary layer will be in
place ahead of this line promoting the potential for a large scale
wind damage event focused on eastern MO/southern IL and western KY.
The majority of the convective allowing models suggest this line
will move east southeast in the evening with the potential for the
apex of a bowing line to impact western KY and into portions of
northwest TN. Convection will likely spread into central KY by mid-
late evening and into the overnight, but the severity of the
convection will likely be determined by how quickly the line can get
here and take advantage of the available instability. Instability
will wane after sunset with nocturnal cooling and the potential for a
near surface temp inversion to set up. If the storms get here after
that happens, we may see more of an elevated storm threat. On the
other hand, should the storms arrive earlier, which is possible if a
large cold pool is generated, then these storms would have better
access to lingering instability.
Much of the machine learning guidance (CSU GFS and HRRR Neural
network) suggest the highest probabilities of severe weather to
remain across eastern MO/southern IL/W Ky with decreasing
probabilities as you head eastward toward the I-65 corridor. Given
the CAM solutions and ML probabilities, agree with the upgrade to an
wind driven enhanced across western KY with a careful expansion of
the slight eastward to the I-65 corridor. Given the modest
instability across our region and forecast low-level shear profiles,
wind damage looks to be the primary weather hazard with this
activity. However, as with any QLCS, spin ups within any bowing
segment (especially at bow apexes) are certainly possible. Isolated
hail would also be possible, but the hail threat would decrease
rapidly by mid-late evening with the loss of instability. Current
thinking is that our "show" would be in the 00-07Z time frame.
Overall confidence in the timing remains pretty good, but we`re
still going to account for a 1-2 window either side of that in case
we get a stronger cold pool to develop pushing convection eastward
quicker.
We expect to be post-frontal by sunrise Friday with perhaps some
lingering showers trailing behind the front over eastern KY. We`ll
see a drying trend in the sensible weather. Highs on the day will
range from the mid 60s over southern IN to the upper 60s/near 70
across much of KY. Continued drying and partial clearing of skies
is expected for Friday night with lows dipping into the upper
30s/lower 40s over southern IN/northern KY with low-mid 40s over
southern KY.
Saturday through Sunday Night...
Current forecast ideas for the weekend haven`t changed all that much
with this forecast cycle. The weekend still looks to be dry and
much cooler as high pressure builds into the region from the W/NW.
Highs Saturday look to top out in the 60-65 degree range in most
areas. Some light precip may slide across the far southern part of
KY Saturday night and into Sunday morning as an upper level wave
pushes through. Lows will range from the upper 30s across southern
IN and northern KY with lower 40s expected south of the Parkways. If
skies end up being more clear that forecast, we could have some
threat of frost across our northern areas. Sunday will see slightly
cooler temperatures with highs ranging from the upper 50s to the
lower 60s. Lows Sunday night will dip into the upper 30s to around
40 in most locations.
Monday through Wednesday...
Latest suite of data suggests that Monday looks to be a bit drier
than in previous forecasts. However, we`ll see precipitation
chances creep back up on Tues/Wed with a wave dropping through the
region. Fairly good signal in the models here for the Tue/Wed
system which will allow us to keep good forecast continuity here.
Highs Monday look to warm a bit over Sunday with readings in the low-
mid 60s with overnight lows in the lower 40s. Highs
Tuesday/Wednesday look to warm back into the upper 60s to the lower
70s with overnight lows in the upper 40s.
&&
.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 719 PM EDT Wed Apr 17 2024
Basically a wind forecast for most of the valid TAF period as a dry
cold front moves through the Ohio Valley. Decent wind surge still
ongoing with gusts solidly over 20 kt as winds veer from SW to WNW.
Expect the gusts to lay down fairly quickly after sunset, but a more
gradual diminishing trend to go light/variable after midnight. After
a brief period of light SE winds Thu morning, we`ll see more steady
S-SW wind in the afternoon with speeds near 10 kt.
Line of storms will be approaching around sunset Thursday, but
timing will depend on the evolution of the MCS, which remains
uncertain. It`s close enough to the end of the 24 hr TAF that it
will not be included at this issuance, but it does impact the SDF
planning period. At this point will run a PROB30 for thunderstorms
in the evening, with the main limiter being the exact timing of
impact.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.
&&
$$
UPDATE...RAS/KDW
SHORT TERM...KDW
LONG TERM...MJ
AVIATION...RAS
Area Forecast Discussion...CORRECTED
National Weather Service Chicago/Romeoville, IL
907 PM CDT Wed Apr 17 2024
.KEY MESSAGES...
- Periods of showers on Thursday with a few thunderstorms and
instances of heavy downpours possible.
- Much cooler over the weekend with frost/freeze concerns,
particularly on Saturday night.
&&
.DISCUSSION...
Issued at 228 PM CDT Wed Apr 17 2024
Through Thursday Night:
We find ourselves beneath mostly cloudy skies this afternoon
with just a few pockets of very light rain found north of
I-88. The clouds and rain are remnants of the same storm system
that brought yesterday`s and this morning`s thunderstorms to the
area, which is now centered up in central Wisconsin. As the low
continues to pull away from the region this afternoon,
subsidence behind the departing system will shave away what
little low level instability we have and the light rain should
call it quits after mid-afternoon. Cloud cover will clear up
nicely through the evening and overnight, but will fill back in
tomorrow morning ahead of our next rain system.
A center of low pressure will spin up in the western Plains
tonight and will quickly trek into the lower Midwest by midday
tomorrow. The behavior and track of the low is not well agreed
upon for tomorrow. What looks to be a small majority of guidance
suggests that the low will track south of the area. The NAM and
Euro are farthest north with the track and pull the center of
the low into the southern reaches of our CWA. A few
thunderstorms in our south look rather likely if the storm takes
such a track with ample instability and forcing near the center
of the low. Thunder parameters drop off pretty quickly as you
move north of the low pressure center. If the low tracks not too
far south of the CWA (a popular opinion among models), tall,
skinny CAPE profiles just north of the low could still promote a
few light thunderstorms in our south, but may favor a bit more
the potential for a period of healthy downpours.
Models are in good agreement that we`ll see intense deformation
of the low level wind field occur on the northwestern
periphery of the system. This will lead to a robust
frontogenetic circulation barreling across the region just
trailing the center of the low. It`s influence on the low itself
is uncertain and is a big contributor to the overall lack of
confidence with this storm. Several models, including a big
chunk of available high-res guidance, have the deformation
stretching and elongating the orientation of the low prior to
moving into the region. Such solutions spread out the coverage
of instability a bit, in some instances pulling it farther north
into our CWA, while also diffusing the magnitude of low level
forcing. The RAP is one such example of this.
The initial push of rain, which may miss parts of the CWA to the
south, will occur during the morning into the afternoon. It
looks like we`ll see a relative lull in activity during the
afternoon. This is before a second round of showers is expected
during the evening. This second round will be a direct result of
the trailing f-gen circulation and presents a concern for an
area of sizable rainfall amounts. A handful of models drop a
swath of 1"+ of QPF on parts of the area underneath this band of
potentially heavy showers. With so much yet to be resolved with
this system, we`ll have to keep a close eye on model trends
into tomorrow.
Doom
Friday through Wednesday:
After several days of unseasonable warmth, a dry and cool
airmass will settle across the region Friday into early next
week. Westerly winds gusting to 30 mph across portions of
northern Illinois combined with the dry airmass will support the
potential for elevated brush fire spread Friday afternoon.
Daytime highs in the 50s Friday through Sunday will moderate
closer to seasonal normals in the 60s by Monday. While a surface
ridge is expected to remain west of the forecast area Saturday
night, some decoupling will allow temps to fall into the 30s
nearly areawide. Will maintain frost mention in the grids for
areas away from the lake and the core of the Chicago metro.
While forecast guidance is in decent agreement with a compact
mid-level wave digging southeast across the Upper Great Lakes
Monday night into Tuesday, somewhat complicated phasing of a
western Canada trough and another longwave trough over Hudson
Bay suggests forecast guidance is subject to notable changes
this far out. At this time, will advertise high-end chance to
low- end likely PoPs with a few embedded thunderstorms.
Kluber
&&
.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 645 PM CDT Wed Apr 17 2024
Key Aviation Messages:
- MVFR CIGS scattering out this evening
- Waves of showers Thursday late morning through the evening,
greatest coverage late afternoon/early evening.
Gusty winds will continue to ease through the evening then
becoming light and variable overnight into Thursday morning.
Directions then trend northeast to east during the morning hours
then increasing in speed during the afternoon out of the
northeast to around 10-15 kts.
MVFR stratus will gradually decrease in coverage through this
evening with VFR forecast overnight into Thursday morning. Waves
of showers are expected late Thursday morning through the
evening. For the first round coverage and intensity will be
lower, which may result in brief dips in CIGS to MVFR. There is
greater confidence in showers developing late afternoon into the
evening, earliest at RFD then progressing east into the Chicago
area terminals with associated reductions in CIGS and VIS to
MVFR as it moves through. Brief dips to IFR can`t be ruled out
with any of the heavier showers. While a rumble of thunder can`t
be ruled out the better potential remains south of the
terminals at this range.
Petr/WMR
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 3 AM CDT Thursday for the IL and IN
nearshore waters.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service San Angelo TX
556 PM CDT Wed Apr 17 2024
...New AVIATION...
.SHORT TERM...
(This evening through Thursday)
Issued at 255 PM CDT Wed Apr 17 2024
Early this afternoon, a dryline was situated across western
portions of the forecast area. Dewpoints ahead of the dryline are
in the mid and upper 60s, with temperatures in the mid and upper
80s, with a few readings in the lower 90s. Isolated thunderstorms
may develop east of the dryline late this afternoon and early
evening. If storms do develop, they could possibly become strong
to severe, with a localized hail/wind threat. The HRRR has been
consistent in generating isolated convection primarily across the
Concho Valley by late afternoon/early evening. Will maintain 20
POPS generally east of a Coleman to Sonora line to account for
this potential. For the rest of tonight, expect low clouds to
develop late tonight across southern sections, which will linger
into the mid/late morning hours Thursday. Winds will remain light
overnight, with mild overnight lows in the mid and upper 60s.
For tomorrow, a surface cold front will enter the Big Country
around noon. The front is forecast to progress slowly south into
portions of the Concho Valley and Heartland counties by late
afternoon, with the dryline extending south across western
portions of the Concho Valley and northern Edwards Plateau.
Moderate to strong instability is expected by peak heating, with
SBCAPE`s in excess of 3000 J/Kg, along with deep layer shear
around 30 kts. Thunderstorm development is possible from the
Concho Valley and Heartland southward tomorrow afternoon into the
evening hours. Any storms that develop will have the potential to
become severe, with large hail and damaging winds the main
hazards. Temperatures will be well above normal tomorrow, with
highs ranging from the upper 80s and lower 90s across the Big
Country prior to frontal passage, to the mid and upper 90s across
central and southern sections.
&&
.LONG TERM...
(Thursday night through next Wednesday)
Issued at 255 PM CDT Wed Apr 17 2024
The main focus for the long term will continue to be the
potential for a widespread soaking rainfall event over the
weekend. Friday will be mostly dry with weak shortwave ridging
overhead. That will be begin to chance, however, as we head into
the weekend. Multiple shortwave troughs are forecast to move
overhead beginning Friday night and continuing into Saturday. This
will provide increasing large scale forcing for ascent. With a
very moist airmass in place (precipitable water values in excess
of 1.5 inches) and the stalled frontal boundary serving as a
surface focus, multiple rounds of moderate to at times heavy
rainfall is expected. A few embedded thunderstorms will also be
possible on Saturday although the severe potential is very low at
this time. WPC does have most of the area under a slight risk for
excessive rainfall on Saturday. While widespread flooding is not
anticipated, some very localized flooding is possible where heavy
rain does fall especially in low lying urban areas. Otherwise,
most of the area should pick up some very beneficial rains which
is certainly welcome given the recent dry conditions. Rain chances
will peak Saturday afternoon and taper off by Sunday morning as
the shortwave trough moves off to the east of the area and upper
level ridging builds in from the west. The remainder of the long
term forecast looks mainly dry at this time.
Temperatures will be much cooler this weekend especially on
Saturday with the expected showers and storms and mostly cloudy
skies. Have undercut the NBM by several degrees for both Friday
and Saturday, with highs only in the 50s and 60s for much of the
area on Saturday. Temperatures will gradually moderate back into
the 80s by Tuesday and Wednesday of next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 556 PM CDT Wed Apr 17 2024
VFR conditions across all sites early this evening, with
south/southeast winds around 10 knots. Expect these conditions to
persist through 06Z tonight, with MVFR ceilings developing at
KJCT, KBBD, and KSOA between 07Z and 10Z early Wednesday morning.
These low clouds will persist through mid morning before
scattering out of the area. Winds will be south to southwesterly
through tomorrow afternoon at KBBD, KSJT, KSOA, and KJCT. KABI
will start with southerly winds, but a cold front is expected to
move into the area during the afternoon, turning their winds to
the north by around 20Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 66 92 55 66 / 10 20 10 10
San Angelo 66 98 60 73 / 20 10 20 20
Junction 68 97 63 83 / 20 30 30 10
Brownwood 66 93 58 69 / 10 40 20 10
Sweetwater 66 93 54 63 / 0 10 10 20
Ozona 66 96 63 78 / 10 10 20 30
Brady 68 94 61 72 / 20 30 30 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...24
LONG TERM....42
AVIATION...20