Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/17/25
Area Forecast Discussion
National Weather Service Cheyenne WY
531 PM MDT Wed Apr 16 2025
.KEY MESSAGES...
- A potentially impactful winter storm is expected Thursday
through Friday. Widespread accumulating snow is likely. Winter
Storm Watches are in effect for portions of southeast Wyoming.
- Remaining unsettled during the weekend through early next week
with chances of showers each day.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 401 PM MDT Wed Apr 16 2025
Another warm day across the area this afternoon with temperatures in
the 60s and 70s. Clouds are gradually increasing across the area
thanks to a weak upper-level disturbance. This disturbance could
bring some light showers to the CWA this afternoon, and perhaps a
rumble of thunder or two as RAP soundings show steep lapse and weak
instability. Shower chances look a little better overnight and west
of the Laramie Range as that disturbance moves overhead.
Impacts from these showers will likely be minimal, however the
mountains could pick up an inch or two of snow.
Heading into Thursday, the weather will make a hard switch from
spring to winter. A potent positively tilted trough will drop
into northern Utah/western Wyoming on Thursday. With this trough
originating in Canada, cold air will drop into CONUS with it. A
strong cold front will gradually push across the CWA during the
day Thursday, as per deterministic GFS and ECMWF. 700 mb
temperatures behind this front will be as cold as -12C, which
puts this anomalously cold air in the 10th percentile for NAEFS
climatology. Ahead of the front in the warm sector, steep lapse
rates and moderate instability will exist across the Interstate
80 corridor from Laramie to Sidney. Some Hi-Res guidance has a
few showers and thunderstorms developing during the afternoon in
this area. While storms are not expected to be severe, cannot
rule out some small hail or strong winds. Given the strength of
the front, precipitation initially starting as rain will quickly
transition to snow. The front will move from northwest to
southeast, so Converse and Carbon Counties will be the first to
see flakes fly. The southern Nebraska panhandle will be the last
to switch over to snow, which will likely happen overnight on
Thursday.
Since this is a later season storm, snowfall amounts could be fairly
impressive. Of course, given the time of year, factors like sun
angle and how quickly the ground can cool off after a few days of
above average temperatures will play a role in snowfall totals.
However, given the strength of the front and that much of the snow
will fall overnight, accumulations are likely, especially across
southeast Wyoming. Went ahead and expanded the Winter Storm Watches
that were in place to the Interstate 80 and 25 corridors. The reason
being that there is still some uncertainty with this system based on
ensemble guidance and another round of models and the addition of Hi-
Res guidance will be useful. Many of the Watch locations are
teetering on the verge of Advisory/Warning criteria, so it is
possible many of these Watches could go either way. For now however,
it is safe to say that the biggest impacts and highest accumulations
will be in southeast Wyoming. The Nebraska panhandle will likely
still see snow, but accumulations should generally be under 2 inches
with the exception of the Pine Ridge.
Diving deeper into this system, a lot of the dynamics favor areas of
heavy, banded snow and orographic upslope flow. The GFS shows areas
of strong mid-level frontogenesis colocated with areas of QPF and
saturated DGZs. The main area of concern for this set-up will be the
Interstate 80 corridor between Laramie and Rawlins. This will likely
lead to heavy snow at times, especially late Thursday afternoon
through Friday morning. Snow accumulations in this area and north of
the Interstate 80 corridor could be anywhere between 4 and 8 inches,
with higher amounts possible in higher terrain. East of the Laramie
Range, orographics and upslope will play a larger role in snowfall
accumulation. North to northeast winds behind the cold front will be
favorable for orographic lift in both the North Laramie Range and
Pine Ridge. Will have to keep an eye on cities along the US-20
corridor, especially in Wyoming where 4+ inches will be possible.
The North Laramie Range will be in a prolonged period of moist
upslope flow, so this area is likely to see the highest snowfall
totals in the CWA for this event. Other areas to watch will include
the South Laramie Range and foothills as well as the Cheyenne Ridge.
The Cheyenne Ridge also favors upslope flow in northerly flow so
areas between Wheatland and Cheyenne could also see upward of 4+
inches of snow. Ensemble means from the GFS and ECMWF are fairly in
line with these totals.
Snow will continue through most of the day Friday, but will
gradually taper off throughout the day from north to south. Minimal
accumulations are expected after sunset on Friday, however there
could be a few lingering snow showers overnight. Behind the
front, temperatures will be much colder for Friday. High
temperatures will struggle to reach freezing for much of
southeast Wyoming, with low 40s expected for the panhandle. Cold
temperatures will continue into Friday night with teens and 20s
expected across the area.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 304 AM MDT Wed Apr 16 2025
A more unsettled weather pattern looks likely in the medium to long
range. Models are in good agreement with the overall pattern across
the Intermountain West and the Front Range through the forecast
period as several chances for precipitation and cooler to near
average temperatures for this time of the year. It definitely looks
like a more typical spring pattern as we head into the last full
week of April.
As we head into the weekend, all models show a slow warming trend
even though temperatures will likely remain below average for mid
April. Northerly flow aloft will remain over the area through
Saturday night with the upper level flow backing into the west on
Sunday. Remaining chilly on Saturday with skies becoming partly
cloudy. However, low level instability and some daytime convection
will result in cloudy skies in the afternoon with scattered rain and
snow showers expected. Sunday looks somewhat drier with moderate
downslope westerly wind expected. It will be milder on Sunday with
temperatures close to average for April 20th (50s to low 60s).
Next week looks mostly unsettled with several upper level
disturbances, embedded in the mean westerly flow aloft, impacting
the forecast area nearly every day. The most potent disturbance and
associated jet max aloft looks to be later Monday and Tuesday, with
some respectable QPF amounts over portions of the forecast area.
Thankfully, precipitation type will be mostly rain outside of the
mountains as 700mb temperatures increase above -5c to 0c. The
mountains typically do well with spring snowfall in these patterns
which some much needed moisture for most of southeast Wyoming and
western Nebraska. Also added thunderstorms to the forecast Monday
and Wednesday with ensemble members and deterministic guidance
showing decent low level instability and increasing moisture/surface
dewpoints.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 521 PM MDT Wed Apr 16 2025
While the flow aloft remains southwest, a weather disturbance
and cold front will move across the terminals on Thursday,
bringing increasing chances for rain and snow.
Wyoming TAFS...For Rawlins, ceilings will lower from 10000 feet
this evening to 5000 feet after 09Z, then to 2000 to 2500 feet
after 12Z, with occasional showers and visibilities of 4 miles
from 12Z to 15Z, with light snow reducing visibilities to
3 miles after 15Z. Winds will gust to 30 knots until 03Z, and
to 23 knots after 15Z Thursday.
For Laramie and Cheyenne, ceilings will lower from 10000 to
5000 feet after 10Z to 13Z, with a chance of showers after 15Z,
reducing visibilities to 4 miles and ceilings to 3000 feet.
Winds will gust to 30 knots at Laramie until 10Z, then to
30 knots after 15Z Thursday, with gusts to 22 knots at Cheyenne
until 03Z, and to 22 knots after 16Z Thursday.
Nebraska TAFS...For Chadron and Alliance, ceilings will lower to
10000 feet after 10Z, and to 1500 to 2500 feet after 14Z, with
showers reducing visibilities to 3 to 5 miles. Winds will gust
to 23 knots at Alliance until 10Z, and to 30 knots after
14Z Thursday, while winds will gust to 24 knots at Chadron
after 14Z Thursday.
For Scottsbluff and Sidney, ceilings will lower to 10000 to
15000 feet after 12Z, then to 3500 to 5000 feet after
15Z Thursday, with showers after 19Z at Scottsbluff reducing
visibilities to 4 miles. Winds will gust to 25 knots until 03Z,
and to 30 knots after 14Z Thursday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Watch from Thursday afternoon through Friday
morning for WYZ101-105.
Winter Storm Watch from Thursday afternoon through Friday
morning for WYZ102-109.
Winter Storm Watch from midnight MDT tonight through Friday
morning for WYZ103-112-114.
Winter Storm Watch from 3 AM MDT Thursday through late
Thursday night for WYZ104.
Winter Storm Watch from Thursday evening through Friday
afternoon for WYZ106-107-113-115.
Winter Storm Watch from Thursday afternoon through Friday
afternoon for WYZ110.
Winter Storm Watch from Thursday morning through Friday
morning for WYZ116.
Winter Storm Watch from Thursday evening through Friday
afternoon for WYZ117-118.
NE...None.
&&
$$
SHORT TERM...SF
LONG TERM...TJT
AVIATION...RUBIN
Area Forecast Discussion
National Weather Service Des Moines IA
650 PM CDT Wed Apr 16 2025
...Updated for the 00z Aviation Discussion...
.KEY MESSAGES...
- Elevated fire weather conditions through the remainder of this
afternoon; gusty breezes prevail into Thursday
- 20-30% chance of a few storms over southern and eastern Iowa
toward and after sunrise Thursday morning with any activity
diminishing by midday.
- Storm chances increase as high as 60 to 80% north of US 34 late
afternoon into the evening hours. Severe storms possible with main
severe hazard being large hail. Initial storms before and around
sunset west of roughly Highway 169 could have damaging wind gusts
and perhaps a tornado.
- More seasonal temperatures this weekend with renewed shower
and storm chances Sunday.
&&
.DISCUSSION...
Issued at 200 PM CDT Wed Apr 16 2025
Upper level water vapor imagery shows mid-level ridging pushing into
the state while an upper low is off the California coast with a
shortwave trough over western Canada. Early afternoon visible
satellite imagery has varying degrees of high clouds spread across
Iowa while low level warm air advection is ongoing. Temperatures are
well above normal well into the 60s and 70s this afternoon. Gusty
winds from the southeast are prevailing along with relative humidity
values between 20 and 30% resulting in elevated fire weather
conditions. There have been a handful of fire hotspots - mainly
prescribed burns - detected by satellite through the veil of clouds.
Into tonight, a wave of strong low level theta-e advection in
concert with a 30 knot low level jet develops ahead of a lead
shortwave trough passing over the state. Convective allowing models
(CAMs) are more muted in their signal of convection toward daybreak
Thursday compared to previous runs of the global models. While there
is still a chance of an isolated severe storms or two with large
hail over our southern or eastern forecast area toward daybreak into
Thursday morning (e.g. MPAS suite vs other CAMs), this is less
likely than thought in previous days.
Any ongoing storms are expected to wane in the morning as the low
level jet weakens and an elevated mixed layer (EML) spreads over the
state ahead of surface low pressure moving over eastern Nebraska.
There looks to remain quite a bit of cloud cover at varying levels
per the latest HREF cloud cover guidance. However, if the cloud
cover ends up being less than forecast, forecast temperatures may
need to be boosted as they are near the 25th percentile of the
initial National Blend of Models guidance. The EML should cap off
any storm development in the afternoon until closer to or shortly
before sunset when storms are expected to quickly develop along a
cold front stretched over northwestern Iowa into east central and
southeast Nebraska. Forecast soundings from the 12z HRRR and 9z RAP
show potential for a brief window of surface based storms, but this
is conditional on the boundary layer heating sufficiently to
overcome any lingering inhibition. If surface based storms do form,
there could be 1000 J/kg or more of MLCAPE and the hodographs also
show favorable low level turning for rotating storms (supercells).
However, winds between 500m and 1 to at times 2km show less speed
shear such that this keeps low level storm relative helicity (SRH)
values low. While large hail will be the main severe concern,
damaging wind gusts and a tornado may be possible in this window
around sunset. With the loss of daytime heating coupled with a
restrengthening EML, any surface based storms will transition to
elevated storms. Interestingly, the full hodograph becomes elongated
as the LLJ develops, but with storms transitioning to elevated they
will likely be only realizing more of a linear hodograph. With good
ventilation and steep mid-level lapse rates, the main concern here
would be large hail.
Storms are expected to weaken and lessen in coverage later in the
evening and especially after midnight. While there may be some
lingering showers into Friday morning, the western Canada trough
elongating back into the southwestern US will aid in pushing the
cold front through the area with increasing subsidence and cold air
advection behind it. Additional convection is likely along the
front, but this looks to be just southeast of our forecast area at
this time later Friday afternoon. The cold front will stall south of
the state and should result in dry conditions on Saturday.
Deterministic models agree that a shortwave trough will track over
or near the state late in the weekend. This along with ensemble
means from the various global of the probability of a tenth of an
inch of precipitation point to renewed shower and storm chances
around Sunday.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 649PM CDT Wed Apr 16 2025
VFR conditions are generally anticipated into the evening with
nothing beyond patchy mid and high level cloudiness. A few
periods of MVFR visibilities due to smoke cannot be ruled out,
but confidence is insufficient to mention at any particular
location at the moment. There is some potential for showers east
into the early morning hours Thursday. Thunder may briefly occur
as well, but confidence is too low to include until short term
trends note otherwise. At least MVFR stratus is expected to
overspread central IA Thursday as low level moisture increases.
Although not mentioned as of yet, chances for thunderstorms
will increase at or just beyond the valid period (18/00z) into
Thursday evening.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
DISCUSSION...Ansorge
AVIATION...Small
Area Forecast Discussion
National Weather Service Goodland KS
526 PM MDT Wed Apr 16 2025
.KEY MESSAGES...
- Showers and storms are forecast this evening and into the
early morning hours. There is a 5-10 percent chance of severe
weather occurring with the strongest storms mainly across
eastern portions of the area with the main hazard being hail
up to half dollar size.
- Fire Weather Watch has been upgraded to a Red Flag Warning as
numerous hours of dangerous fire weather conditions forecast.
Wind shift associated with a wind shift remains forecast as
well later in the day Thursday.
- Patchy blowing dust resulting in some reduction of
visibilities is possible across western portions of Cheyenne
and Kit Carson counties Thursday. A more impactful issue may
be the dust lofted into the air may result in hazy conditions
and degraded air quality further downstream however.
- Cooler and wetter Friday through the weekend with rain and
even snow chances. Little to no snow accumulation is expected
at this time. Higher confidence however in freezing
temperatures across much of the area along with hard freeze
potential Friday morning through Sunday morning.
&&
.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 153 PM MDT Wed Apr 16 2025
Warm temperatures across the area for the remainder of the day in
the 80s. Winds overall are forecast to remain on the lighter side as
the CWA is in between synoptic systems although some sporadic
wind gusts around 20-25 mph are possible through the afternoon
due to deep mixing. The main focus for day will be on the shower
and potential thunderstorm risk for this evening and into the
early morning hours. A 700mb shortwave emanating from the
Rockies is forecast to move onto the Plains this evening and
interact with a developing low level jet across SW Kansas.
Initially some high based showers do look to develop off of the
Palmer Divide and move into western Kansas with essentially no
impact. Any precipitation looks to be minimal due to the dry
air in place at the surface. A couple hundred j/kg of both MU
and SBCAPE does look to be in place so a rogue lightning strike
can`t be ruled out with this activity. Moisture advection will
be ongoing across eastern portions of the area due to the low
level jet as dew points rise in the low to mid 50s along and
east of Highway 83. As these showers move into the better
moisture and increasing CAPE up to around 1000-1500 j/kg. The
environment overall will be favorable for the potential for
large hail up to half dollar size due to lapse rates around
8-8.5C/km, wind shear of 50-60 knots and straight line
hodographs. With all of this said the severe threat does look to
be conditional and will be dictated on the timing of the
moisture return. There does remain some scenarios where the wave
moves through a little quicker and shunts the moisture return
to the east such as the HRRR and RAP. Other guidance such as the
RRFS and NAMNEST has the moisture return making it as far west
as Colby and would end up being a more impactful scenario where
the storms would have a longer residence time in the more moist
air which would increase the severe threat. Overall, confidence
in severe weather with all of this said is currently around
5-10% and would be favored across Gove, Sheridan, Graham and
potentially as far north as Norton counties.
Thursday, a surface low remains slated to to develop across western
Kansas, further to the north across Nebraska a stationary front is
forecast to slowly move southward as a cold front. Confidence
remains high multiple hours of critical fire weather occurring
across most of the Fire Weather Watch, as a result have upgraded the
entire watch to a warning. Dangerous fire weather conditions are
forecast for Cheyenne (CO), Kit Carson, Wallace, Greeley and Wichita
counties as those counties as very dry air with RH values falling
into the single digits and wind gusts up to 45 mph are forecast to
occur; across Cheyenne (CO) and Kit Carson counties would not be
surprised if some 50+ mph winds can occur. Sherman through Graham
and Logan and Gove counties appears not have as strong of winds due
to a slightly weaker wind field however wind gusts around 35 mph
remain forecast There still does appear to be limited area that
still may see some organized blowing dust across Cheyenne and Kit
Carson counties where the winds will be stronger, however as
mentioned the past few days 2-2.5km lapse rates remain very high
which would still support dust filtering out and leading to hazy
sky. I did re-add in the patchy blowing dust wording into the
forecast for these two counties due to the strength of the wind
being highest across that area and the potential for plumes of
dust developing across Lincoln,Crowley, Kiowa counties and
moving into the CWA. Elsewhere, still can`t rule out some
splotchy, localized dust issues especially near open fields but
think any dust impacts would be few and far between.
Onto the wind shift/cold front. There does appear to be the
potential for an initial wind shift in the form of a pre
frontal trough/pseudo stationary front setting up across the
Highway 36 corridor where winds will be northerly and slightly
higher dew points resulting in RH values in the low to mid 20s.
The main surge of cold air advection and the impactful wind
shift doesn`t appear to happen until later in the day as the low
moves off to the east which will then allow that pseudo
stationary front to surge southward. Very good agreement with
guidance of 10-13mb pressure rises with the front resulting in
40-50 mph wind gusts with the front, a rogue gust of 55+ mph is
also possible.
Behind the cold front, precipitation chances have decreased some due
to a lack of forcing. There was some concern that this was due to it
being drizzle, but don`t think that drizzle or even freezing drizzle
where it is coldest will be an issue due to a high probability
of ice being present in the clouds. The precipitation chances at
this time are favored to be across the higher elevations of
Yuma and Kit Carson counties where rain will transition to snow
as cold air advection continues to push in.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 153 PM MDT Wed Apr 16 2025
The active pattern is forecast to continue into the extended period
as well along with a much cooler air mass in place Friday and into
the weekend. A subtle surface trough within the flow of the main
trough is forecast to move across eastern Colorado through the day
Friday in wake of the cold front continuing rain and snow chances
for the eastern Colorado counties. Not anticipating much if any
impacts with this as ground temperatures are very warm in the 50s
which should help keep any accumulations from ongoing. High
temperatures for the day are forecast in the upper 30s across
eastern Colorado to the mid 50s across eastern portions of the CWA.
Another hard freeze is also likely for much of the forecast area
Saturday and Sunday mornings.
Friday night and into Saturday, the trough is forecast to move
slowly to the east. My overall expectations for precipitation
remain tempered due to a more southern track of the trough and
easterly ejection into Kansas. However, there are some ensemble
members that do try to develop a secondary 80-100 knot jet
streak towards the tail end of the larger scale trough. If this
does occur then the chances for precipitation would increase.
The ECMWF ensemble members favor more snow due to colder
temperatures being in place, with accumulating snowfall well
into NW Kansas. This is also seen as well with a shift of tails
on the 00Z EFI but would be more a low confidence higher impact
scenario. Only a handful of GEFS ensemble members show show
this jet streak and has temperatures not as cold as the ECMWF.
Since this is a fairly new development I don`t want to
completely latch onto this but it does bear watching at this
point. Precipitation chances are forecast to continue through
Sunday morning and then slowly waning as the day goes on.
Into the start of the new work week, additional waves are forecast
to continue to move through the area as apart of a larger scale
longwave trough across the NW CONUS. Moisture return is also
forecast to continue to increase starting late Monday and
through the day Tuesday which may lead to some thunderstorm
chances if the timing of the waves can align just right and
continue through the rest of the work week. With this still
being 6+ days out overall confidence in this occurring is low at
this time as a lot can and more than likely will change with
guidance.
As for temperatures, as mentioned above a cooler air mass is
forecast to be in store to start the week with freezes and hard
freezes likely for most of the area Friday through Sunday morning.
Those with any gardening or other vegetation interests will want to
assure proper precautions are taken place ahead of the colder
weather. A return to more seasonable conditions does look to occur
to start the new work week.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 524 PM MDT Wed Apr 16 2025
VFR expected to prevail at both KGLD and KMCK through the TAF
period. There is a low probability, less than 20%, of a shower
or thunderstorm impacting either terminal through about 08z
tonight. Brief gusty downburst winds will be the main hazard
near any thunderstorms that develops.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from 10 AM MDT /11 AM CDT/ to 9 PM MDT /10 PM
CDT/ Thursday for KSZ013>016-027>029-041-042.
CO...Red Flag Warning from 10 AM to 9 PM MDT Thursday for COZ253-
254.
NE...None.
&&
$$
SHORT TERM...Trigg
LONG TERM...Trigg
AVIATION...024
Area Forecast Discussion
National Weather Service Grand Rapids MI
725 PM EDT Wed Apr 16 2025
.KEY MESSAGES...
- Dry During The Day Thursday
- Severe Storms Possible Friday
- Lower Confidence Weekend Forecast, Showers/Storms Possible
&&
.DISCUSSION...
Issued at 305 PM EDT Wed Apr 16 2025
- Dry During The Day Thursday
Conditions will stay dry through the daylight hours, with clouds
increasing through the day. Southerly winds will keep things quite
dry with RH values falling into the upper 20s to 30s in the
afternoon. Combined with south winds gusting to around 20 mph in the
afternoon, fire danger will be elevated Thursday.
- Severe Storms Possible Friday
Friday will feature the potential for two rounds of severe storms.
One in the early morning, and one in the evening.
Thursday Night into Friday morning will feature showers and storms
associated with a warm frontal boundary lifting north across the
area. A strengthening low-level jet will advect warm air and
steepen mid-level lapse rates and produce around 1000 J/kg MUCAPE.
Forecast soundings from the RAP taken from MKG and BIV near 5am
Friday show decent HGZ CAPE as well as 30-45 knots of effective
shear. This would be enough to bring the potential for an isolated
hail threat if any storms occuring Thursday in Iowa survive long
enough to reach West Michigan. Soundings show storms Friday
Morning would be elevated (rooted near 850-800mb) meaning cold
lake Michigan water will not be a relevant factor.
Much of the day Friday looks to be dry as a stout elevated mixed
layer will be in place near 850 mb. This will pair with mid-level
height rises on the order of 2-4 dam much of the day to suppress
convection. During this time southerly winds will lead to a warm
front moving north with mid 50s to low 60s dewpoints south of it.
Highs south of the front look to be well into the 70s.
This will lead to a conditional threat of severe weather Friday
evening into the early overnight hours, coinciding with the arrival
of a slow-moving cold front from the west. Forcing from the cold
front in combination with mid-level height tendencies going neutral
brings the potential for convection to develop in the latter half of
the evening into the early overnight hours. Conditional on
convection developing, the environment will be favorable for
storms to quickly become severe. Mid-level lapse rates on the
order of 8 to 9 C/km will translate to 1000-1500 J/kg of CAPE.
Deep layer shear will be present in abundance with deep layer
shear values in in excess of 45 knots. Storms across Southern
Michigan will be surface based while storms across northern- lower
will be elevated. At this range, the primary hazards in any
storms that develop will be large hail and damaging winds. As
previously noted, severe weather will be conditional on a
favorable overlap of frontal timing/cap erosion and instability
so expect fine tuning of the forecast over the next 48 hours as we
move into CAM range.
- Lower Confidence Weekend Forecast, Showers/Storms Possible
The synoptic pattern becomes less clear into the weekend, as
questions arise about the possible development of a cutoff low
across the western CONUS. Cluster analysis shows that the
uncertainty lies in how a northern stream mid-level wave interacts
with the western CONUS wave affecting the extent of mid-level
forcing. Periods of showers are possible through the weekend,
particularly across southern Michigan closer to a front that
stalls over the Ohio Valley. Several different guidance suites
then bring a low pressure system and associated rain chances to
West Michigan in the Sunday Night into Monday timeframe, though
the exact track and strength of this feature remains uncertain.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 720 PM EDT Wed Apr 16 2025
VFR conditions expected through the period due to high pressure
overhead. Wind will become gusty from the southwest Thursday
afternoon ahead of the next system that will arrive Friday.
&&
.MARINE...
Issued at 305 PM EDT Wed Apr 16 2025
Winds increase into Thursday, peaking around 25 knots near Big and
Little Sable Points. Southeasterly/off shore flow will keep the
greatest waves offshore initially. Late Thursday into Friday winds
veer to southerly causing waves hazardous to small craft to build
closer to the western shoreline. Waves likely diminish below Small
Craft Advisory levels in the Friday Night/Early Saturday timeframe.
The other marine concern is for two main rounds of thunderstorms.
The first arrives early Friday morning, where a low chance of hail
and/or brief gusty winds exists. A second round of storms is
possible Friday evening, though it is questionable whether Lake
Michigan will be affected or not.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Thomas
AVIATION...04
MARINE...Thomas
Area Forecast Discussion
National Weather Service Indianapolis IN
1049 PM EDT Wed Apr 16 2025
.KEY MESSAGES...
- Increasing clouds tonight, patchy frost possible northeast of
Indianapolis
- Rain showers with perhaps a rumble of thunder on Thursday
- Warming trend towards the end of the week with strong to severe
Thunderstorms possible late Friday
- Multiple rounds of rain Friday night through this weekend with
the potential for returned river flooding
&&
.FORECAST UPDATE...
Issued at 951 PM EDT Wed Apr 16 2025
No significant changes were needed to the forecast with this update.
Across Illinois, weak upper forcing has created some sprinkles
falling from mid-level clouds. As these have tried to come east,
they evaporate with the very dry air across Indiana.
Will have to watch these overnight as the mid levels try and moisten
up across central Indiana. The low levels w4ill remain dry, so if
anything occurs, it should be just sprinkles. For now though have
left the forecast dry.
Temperatures look okay with clouds continuing to gradually increase
from the west. With the northeast seeing the clouds last, patchy
frost still looks possible there.
&&
.SHORT TERM (This evening through Thursday)...
Issued at 259 PM EDT Wed Apr 16 2025
Troughing is currently taking hold over the West Coast with ridging
working its way into the Great Plains. Surface high pressure is
currently passing through the Midwest, and will slide eastward
reaching the East Coast tomorrow.
Surface winds here in Indiana are currently out of the northwest,
but should go calm overnight as the high passes by. Once its to our
east, expect winds to increase again and become southeasterly. With
calm wind conditions overnight, lows may dip into the upper 30s in
rural areas. Some patchy frost is possible, mainly northeast of
Indy. Increasing high clouds could lessen radiational cooling
potential somewhat.
Low pressure taking shape in the lee of the Rockies, associated with
the deepening trough, will allow for a warm front to lift
northeastward out of Missouri overnight. This front approaches
Indiana tomorrow morning with advection-driven showers at times
ahead of its arrival. Some elevated convective elements are possible
as well, but profiles do not support robust elevated convection at
this time. A rumble of thunder is still possible, however.
Confidence regarding high temperatures on Thursday is a bit lower
than normal, since coverage of rain showers and timing of the warm
front are not yet pinned down. Greater coverage of showers and a
slower front could allow temps to be lower than currently shown.
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 259 PM EDT Wed Apr 16 2025
Thursday night and Friday...
Anomalously warm conditions are expected early in the extended as
south/southwesterly flow strengthens ahead of an approaching low
pressure system. Look for lows near the mid 50s Thursday night with
highs in the upper 70s to near 80F on Friday. The pressure gradient
strengthening will also favor increasingly windy conditions,
especially during the day Friday as diurnal mixing into a strong LLJ
helps transfer stronger gusts to the surface. Wind gusts around 30-
40 mph appear likely.
Precipitation is not expected Thursday night as a warm front
continues to lift north of central Indiana with little to no forcing
in place. Guidance then shows a strong EML developing on Friday
which is likely going to limit the potential for convection through
the day.
Friday night through early next week...
The low pressure system moves in late Friday promoting widespread
precipitation and the potential for severe weather. Persistent
strong S/SW flow will aid in sufficient destabilization. Aloft,
increasing mid-upper level winds as the parent trough approaches
will provide favorable deep-layer shear for organized thunderstorms.
Some of these storms could be severe with the primary threats being
damaging wind gusts and large hail. The question that remains is how
long will it take for increasing lift and warm-moist advection to
erode the EML. Most guidance suggest this occurs during the evening
though a few models hold off convection until later in the overnight
period.
There is increasing confidence in a flooding threat over the
weekend. An upper ridge remaining anchored off the southeast coast
along with broad troughing over the central CONUS will continue to
pump anomalous moisture towards the area. This along with a frontal
boundary expected to stall across the region late Friday into
Saturday supports the threat for subsequent rounds of convection.
Guidance suggest the potential for 1-3 inches of rain with locally
higher amounts possible due to convective elements. Expect an
elevated flash flooding threat along with renewed minor flooding for
portions of the main stem rivers.
Rain chances finally begin to taper off on Monday as the stalled
front shifts eastward. Dry conditions are expected to return Monday
night into Tuesday before another system approaches towards midweek.
Temperatures remain near normal over the weekend into early next
week before warming up.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 1045 PM EDT Wed Apr 16 2025
Impacts:
- VFR Conditions expected.
- Rain showers possible after 17Z. Low chance thunder.
- Wind gusts to around 25kt possible Thursday afternoon.
Discussion:
VFR conditions are expected through the period.
GOES16 shows high cloud over IL poised to advect into Indiana and
across the TAF sites as upper ridging over the area slowly departs.
Forecast soundings show this arriving overnight as some saturation
within the upper levels.
A warm front will pass across Central Indiana during the afternoon
on Thursday. This will result an an isolated period of light rain
showers HRRR shows a thin band of precipitation moving across the
area. For now, have used a window of VCSH too account for this. The
caveat against this precip will be the very dry lower levels.
As the TAF sites arrive within the warm sector on Thursday evening,
VFR conditions will continue with southerly winds.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...50
SHORT TERM...Eckhoff
LONG TERM...Melo
AVIATION...Puma
Area Forecast Discussion
National Weather Service Las Vegas NV
759 PM PDT Wed Apr 16 2025
.SYNOPSIS...Above normal temperatures today will give way to
cooler, unsettled weather going into the weekend. A storm system
will bring gusty winds Thursday and Friday with the chance for
showers and a few thunderstorms across the area.
&&
.UPDATE..Winds remain breezy across the region as southwest winds
increased with the strengthening pressure gradient. Widespread gusts
20-30 MPH have been reported so far. Gusts over 30 MPH have been
reported in the Western Mojave Desert, and these winds are expected
to increase further with the strenghtening 850mb jet and terrain
enhancement. The Wind Advisory has gone into effect for this area as
increasing winds and the potential for wind impacts are likely at
times tonight through Thursday. Elsewhere, winds will drop back
slightly but continue to gust 15-25 MPH through eastern San
Bernardino, CLark, into Mohave County tonight.
Current satellite suggests a deformation zone is setting up over
Inyo County through southern Nevada into southwest Utah. The HRRR
has been hinting at this set up in the past few runs and wants to
develop scattered showers as the atmosphere stretches and squeezes
itself out, which is what is starting to happen as latest radar
returns show isolated showers from Olancha, CA to Desert Rock, NV to
Hiko, NV. Isolated showers may continue over this area through the
night, however rainfall will be light as PWATs are low and dewpoints
remain in the teens to 20s. The better moisture and forcing will
arrive Thursday morning and afternoon, until then precipitation will
be un-impactful as it struggles to organized or overcome the dry low
levels. Earlier today, thunder was reported at times in Inyo County
into the central Great Basin, but this should end with sunset as
instability wanes overnight. Further south, it will remain dry
tonight.
-Nickerson-
&&
.PREVIOUS DISCUSSION...348 PM PDT Wed Apr 16 2025
.SHORT TERM...through Friday Night.
A complicated weather pattern is setting up over the next few days
as low pressure off the southern California coast slowly transitions
to an open wave and moves ashore. As it translates eastward,
southwesterly wind will pick up in the western Mojave Desert,
bringing winds gusting to 40 mph or more. As such a Wind Advisory
begins this afternoon and lasts into Friday morning for that area.
To add to the complexity, a strong, cold low pressure system will be
diving southward from western Canada. The associated cold front will
bring strong northerly winds gusting 45 to 50 mph to Esmeralda and
central Nye counties. A wind advisory is in place for those areas
from Thursday morning through Friday evening. The cold front will
also bring showers and thunderstorms to much of southern Nevada and
Mohave County Thursday. Lift associated with the front and
instability due to the cold upper airmass behind the front will make
thunderstorms a real possibility Thursday afternoon and evening.
Rainfall totals will generally be low, below 0.10 inches with
northern Mohave County receiving around .25 inches. Locally higher
rainfall totals are possible in stringer thunderstorm cells. The
highest elevations in the mountains could see a small bit of snow,
but nothing impactful. Very dry and cool air will be in place Friday
with temperatures across southern Nevada and northwest Arizona a
good 10 degrees below normal.
.LONG TERM...Saturday through Tuesday.
As we head into the weekend, ensemble guidance has the closed low
pushing out to the east, leaving us under a drier northwesterly or
zonal flow. Not only do precipitation chances wane, but temperatures
begin to moderate to seasonal values. By Sunday, forecast highs are
near or slightly above normal, and hold fairly steady into next
week. The synoptic pattern in the extended will favor inside sliders
or shortwaves passing well to our north. As these move by, periods
of gusty winds are possible.
&&
.AVIATION...For Harry Reid...For the 00Z Forecast
Package...Southeast winds will quickly turn to the south-southwest
by early evening with sustained speeds around 12 knots and
occasional gusts to 20 knots. Winds will gradually diminish after
05Z, but occasional gusts to 20 knots will still be possible
throughout the night. A period of lighter winds is forecast around
daybreak tomorrow, but gusty southwest winds will return after 17Z
and persist into tomorrow evening. VFR conditions will continue
into Thursday morning. A frontal system moving into the valley
tomorrow afternoon will bring the chance of a few convective showers
after 21Z. An isolated thundershower can also not be ruled out,
which could result in a period of gusty, erratic winds.
For the rest of southern Nevada, northwest Arizona and southeast
California...For the 00Z Forecast Package...Conditions at the Las
Vegas area terminals will be similar to what is described above for
Harry Reid, except winds will remain mainly southerly at KHND
through the period. Scattered showers and a few embedded
thunderstorms will persist over the higher terrain surrounding KBIH
into this evening, with winds remaining erratic due to the nearby
convective activity. After sunset, winds will settle in a northerly
direction and remain from that direction into tomorrow. Winds at
KDAG will remain westerly through the period, with gusts increasing
to near 40 knots by late tomorrow morning. In the lower Colorado
River Valley, the typical south to southwest winds with occasional
gusts to 25 knots can be expected through tomorrow. Away from any
shower activity, VFR conditions will prevail with bases remaining
10kft AGL or higher. Additional showers and embedded thundershowers
are likely tomorrow across the Sierra and areas near and north of
Las Vegas.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Berc
LONG TERM...Woods
AVIATION...Planz
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