Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/01/21
Area Forecast Discussion
National Weather Service La Crosse WI
1015 PM CDT Fri Apr 30 2021
.SHORT TERM...(This evening through Saturday)
Issued at 206 PM CDT Fri Apr 30 2021
There are a couple of subtle features to watch for the possibility
of some rain development tonight and Saturday. The first are a
couple of short wave troughs that will top the upper level ridge and
move across the region. The first wave looks to come across this
evening with the best pv advection moving across northern Minnesota
and Lake Superior. Very little additional forcing looks to occur
with this first wave and looking at RAP forecast soundings from
KMDZ, what lift that does occur, is in the low levels below the
saturated mid-level layer. As a result, expecting this wave to go by
with only some cloud production. The second short wave trough to
come over the ridge overnight looks to take a slightly farther south
track. This wave looks to be weaker than the first and only produces
some very weak pv advection as it comes across. However, it looks to
have some better companion forcing with it. An area of low level
warm advection ahead of the wave helps to generate 4 to 6 ubar/s of
up glide on the 295K isentropic surface across northern Wisconsin.
Some weak low level moisture transport looks to be focused into this
area and there looks to be a weak band of frontogenesis in the 850
to 700 mb layer as a weak front moves into the region. This may be
enough to generate a narrow band of showers for some locations
generally north of Interstate 94.
The second chance then looks to be tied to the front late Saturday
afternoon. The front is expected to sink to about the Interstate 90
corridor. Another short wave trough looks to top the ridge and will
be approaching from the northwest by late afternoon. The low level
moisture transport looks to start increasing late in the afternoon
into the front and the frontogenesis, while still weak, looks to be
a bit deeper existing in the 850-500 mb layer. All this may be
enough to generate some showers over the eastern sections late in
.LONG TERM...(Saturday night through Friday)
Issued at 206 PM CDT Fri Apr 30 2021
From Saturday night into Sunday, the best moisture transport and
forcing looks to be north of the Interstate 94 corridor. There are
even some models that suggest that it will be even farther north
than that. With most unstable CAPES up to 250 J/kg, scattered storms
will be possible. The elevated shear (2-6 km) remains less 20
knots, so not anticipating any storms becoming severe.
From Sunday night into Monday, the front moves southeast through the
region. The GFS continues to be the wettest with this system
(probably an outlier based on its ensemble and the EPS). With most
unstable up to 250 J/kg, will keep scattered storms in the forecast.
Like Saturday night and Sunday, the shear remains weak, so not
anticipating organized severe weather.
With northwest flow aloft from Tuesday through Thursday, cooler-than-
normal temperatures are expected. High temperatures will be mainly
in the 50s and lower 60s (maybe just the 40s for Thursday) and low
temperatures in the 30s and 40s. It will be dry from Tuesday into
Wednesday and then a low pressure system will provide a chance of
showers for Wednesday night into Thursday. Rainfall totals will be
likely less than a half-inch.
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1015 PM CDT Fri Apr 30 2021
Cigs: sct-bkn mid/high level vfr clouds expected through Sat night,
then expecting an increase in low level saturation Sunday morning.
Could/should drop into MVFR later in the day Sun, ahead of
approaching cold front/upper level shortwave trough.
WX/vsby: warming in the low layers of the atmosphere coupled with
weak shortwave trough a loft should result in scattered -shra across
northern WI overnight. How far southwest they extent will rely on
how much saturation is available - with bufkit soundings holding
mostly mid level moisture (10kft). Could see an isold -shra at KLSE,
but not enough there to add to the forecast for now. Eitherway,
impacts/amounts would be minimal. The next best chance for shra/ts
comes Sun/Sun night.
Winds: light winds on the increase overnight as sfc pressure
gradient tightens. Mostly south/southeast, with some turn to the
west then for Sat afternoon. Some higher gusts likely overnight/Sat
morning. In addition, increasing winds by 1500 ft will bring LLWS
concerns to KLSE overnight into the mid morning hours Sat.
Issued at 206 PM CDT Fri Apr 30 2021
On Saturday, it continues to look like there will be the possibility
of critical fire weather conditions developing mainly south of
Interstate 90 in Wisconsin. The combination of a tight pressure
gradient and diurnal mixing, southwest winds will climb up into the
15 to 25 mph range with wind gusts up to 40 mph. The strongest wind
gusts will be across northeast Iowa and southwest Wisconsin. The
strongest winds will be during the late morning and early afternoon
and then they will move east of the area during the mid to late
Soundings suggest that we will mix up into the 750-800 mb range.
This would likely result in dew points falling into the mid-40s.
With high temperatures in the mid and upper 80s, afternoon relative
humidities will likely fall into the lower and mid 20s.
With the combination of winds and low relative humidities, we will
could potentially see critical fire weather conditions. After
coordinating with Wisconsin partners, it was the consensus to issue
a Fire Weather Watch there.
Elsewhere, there will be elevated fire weather conditions.
WI...Fire Weather Watch from Saturday afternoon through Saturday
evening for WIZ034-041>044-053>055-061.
Area Forecast Discussion
National Weather Service State College PA
1102 PM EDT Fri Apr 30 2021
A narrow high pressure area will build across the Commonwealth
later tonight and Saturday, to bring dry weather and diminishing
winds. As our prevailing flow turns into the southwest, much
warmer temperatures will return on Sunday.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Skies have across southern and western Pa this evening, as large
scale subsidence and much lower pwats overspread the region.
However, low level instability associated with upper trough is
likely to keep snow/rain showers going across the mountains
north of KIPT this evening. Temperatures at 00Z are still above
freezing over the northern mountains, but suspect the higher
terrain along the NY border will see a quick coating on grassy
areas before snow showers taper off around midnight.
00Z observations are still reporting gusts to around 40kts
across a good portion of central Pa. Latest RAP soundings
indicate winds will remain up through late evening, then
diminish late tonight, as the pressure gradient relaxes and high
pressure approaches from the midwest.
Latest guidance continues to support low temperatures near
freezing over portions of the Allegheny Plateau, so a Freeze
Warning remains up for those counties where the growing season
has begun. Outside of the Freeze Warning locales, lows by
daybreak should range from 35-40F.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Saturday should be a pleasant day as surface ridging builds
into the Commonwealth. The day may start a little breezy in the
Susquehanna Valley and southern Poconos, but winds should be
diminishing there with time. Plenty of sunshine should push
temperatures to 60-65F over much of the area by afternoon, with
upper 50s along the spine of the Appalachians.
By late in the day, surface high will pass off the Mid Atlantic
coast and warm advection will ramp up ahead of a strong low
level jet lifting into the eastern Grt Lks. Expect clouds to
overspread the northwest counties by evening ahead of this
feature, with a few showers possible up there toward dusk.
Saturday night, a warm frontal boundary will develop near the
PA/NY border, with enough moisture advection and forced lift for
at least some isolated showers over the northern tier.
Elsewhere, it should remain dry. Overnight lows will be much
milder than the previous night, only dropping into the upper
40s-lower 50s range.
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Q-stationary frontal zone near PA/NY border keeps low POPs in
the northern tier on Sunday. The big story by the end of the
weekend will be much warmer temperatures returning to CPA with
highs +15F warmer than Saturday in the 70-80F range.
The early to mid week period looks rather unsettled with a pair
of southern stream shortwaves likely bringing rounds of showers
and t-storms Monday through Wednesday. Model and ensemble data
favor a deepening trough over the Eastern U.S. from late week
into next weekend with potential for a coastal low near the
Despite a modest cool down Sunday into Monday, temperatures
should remain above average early next week. NBM trended warmer
and wetter during this period. Expect a seasonably cooler trend
during the mid to late week period with below average daytime
temps to close out the week.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Winds continue to gust up to 40 kts in the southeast and up to
30 kts elsewhere early tonight. Surface winds will decrease
and become less gusty as the night continues, but WS020 will
continue with winds above the surface remaining strong through
sunrise. Expect winds to diminish somewhat Saturday. After snow
showers across the northern tier dissipate later tonight, VFR
conditions will prevail across central PA through Sat.
Sun...MVFR in showers across the norther tier.
Mon...Mainly VFR conditions, but a chance of showers late NW.
Tue...Mainly VFR conditions, but a chance of showers.
Wed...Restrictions possible in rain showers.
Wind Advisory until midnight EDT tonight for PAZ012-018-019-
Freeze Warning until 8 AM EDT Saturday for PAZ004-017-018-024-
Wind Advisory until 2 AM EDT Saturday for PAZ035-036-056>059-
Area Forecast Discussion
National Weather Service Duluth MN
1025 PM CDT Fri Apr 30 2021
.DISCUSSION...(This evening through Thursday)
Issued at 349 PM CDT Fri Apr 30 2021
Rain showers this evening into Saturday morning, followed by a warm
and dry Saturday afternoon with near critical fire weather
conditions, and slightly below normal temperatures into next week
highlight the forecast.
Rain showers ahead of a warm front across North and South Dakota are
forecast to slowly propagate first across northeast Minnesota this
evening in a zone of low level warm air advection. Additional
rain shower development is expected through the night and into
Saturday morning across much of northwest Wisconsin and northeast
Minnesota. However, low level dry air in place may limit how much
precipitation is able to reach the ground, especially this
evening across northeast Minnesota.
Saturday afternoon will be dry with deep mixing expected behind the
warm front and with the passage of a weak cold front/surface
trough with near critical fire weather conditions. High
temperatures on Saturday will be in the 70s, possibly a few lower
80s from the Brainerd Lakes through the Hayward and Philips areas,
with relative humidity falling into the 23 to 28 percent range
which is close to the HRRR trends. Afternoon winds will be
strongest for the Arrowhead and Iron Range of Minnesota with
northwest winds sustained near 10-15 mph with gusts to near 20 mph
with mixing of 8000-10000 kft. Elsewhere across northeast
Minnesota and northwest Wisconsin, northwest winds will be
slightly weaker sustained around 10 mph with gusts of 15-20 mph.
There is some uncertainty how much high level cloud cover there
may be, which would filter some of the sunshine and possibly keep
temperatures a few decreases cooler and relative humidity slightly
A cold front is forecast to propagate from north to south across
the Northland Saturday night into Sunday morning. With multiple
impulses arriving out of the western CONUS trough, scattered rain
showers are expected on Sunday. It will also be cooler, with highs
in the 60s, and only the 50s downstream of Lake Superior with
strong northeast winds off of the Lake.
Looking ahead, the 12 UTC global suite favors upper level
troughing across the region mid to late next week, with slightly
below normal high temperatures in the 50s and sporadic light
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 705 PM CDT Fri Apr 30 2021
VFR conditions will continue through this evening despite light
rain showers crossing the terminals as a warm front approaches.
Low level wind shear will develop as southwesterly winds increase
aloft tonight and into Saturday morning for all terminals. Expect
another round of light rain around sunrise Saturday with VFR
conditions across all terminals outside of precipitation.
Issued at 1007 PM CDT Fri Apr 30 2021
An area of low pressure will march southeast towards Lake Superior
tonight into Saturday morning causing the pressure gradient to
tighten. The system is quite warm, so the stable surface of Lake
Superior will make it difficult to mix the winds to the surface.
So, for now, opting to keep headline free. Winds will switch on
Sunday morning to the northeast and increase in speed giving
probable small craft advisory conditions and larger waves to much
of western Lake Superior.
.PRELIMINARY POINT TEMPS/POPS...
DLH 44 76 43 50 / 40 0 10 40
INL 42 75 41 65 / 50 0 10 30
BRD 48 81 49 63 / 10 0 10 40
HYR 44 80 46 61 / 30 10 10 60
ASX 43 79 41 53 / 40 10 10 50
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1024 PM EDT Fri Apr 30 2021
Saturday looks cool and breezy but mostly dry as low pressure
exits through the Canadian Maritimes. A frontal system will
approach the region late Sunday. A large area of low pressure
will cross the region Monday into Tuesday with another system
following on Wednesday. Clearing will follow on Thursday as the
low exits into the Canadian Maritimes. A weak area of high
pressure then builds over the region Friday.
.NEAR TERM /THROUGH SATURDAY/...
10:15 PM Update...Slight adjustments to the forecast tonight to
raise pops up a bit over the next 3 hours as precip is hanging
on a little longer than anticipated. Water Vapor imagery shows
the upper level low tracking across southern New England which
is the main feature keeping the light rain and shower activity
going tonight. This feature continue to track eastward over the
next 3 to 6 hours. Rainfall will end from north to south tonight
with precip coming to end for almost all areas by daybreak. Cool
and raw night but visibilities are staying elevated due to a
strong enough pressure gradient allowing for low level mixing.
6:30 PM Update... Made some adjustments to PoPs based on radar,
which shows a band of light to moderate raining continuing to
pivot through western Maine portions of east-central New
Hampshire. Generally expecting this band to continue to move
south through the early evening before moving offshore. Upslope
showers will continue through much of the night and with falling
temperatures some of this will likely fall as snow in the
mountains. Also adjusted winds to better match observations. As
expected, southern New Hampshire continues to be quite gusty
and this will continue for the next few hours before diminishing
The latest HRRR continues to show precipitation
wrapping back south this evening as a second area of upper level
support crosses the region. The greatest chance for showers
will be in the upslope regions exposed to a westerly flow. Over
the highest peaks, the precipitation will continue to change to
sleet and snow where accumulating snowfall will likely occur
above 3500 feet as cooler and drier air enters the region.
Rivers will remain elevated with a couple basins nearing action
stage across portions of New Hampshire.
Patchy fog will continue, mainly over eastern areas that have
not received the drier air.
Overnight lows will be coolest over northern and western New
Hampshire with readings dropping into the 30s for overnight
lows. Lower 40s can be expected over eastern sections.
.SHORT TERM /SATURDAY NIGHT/...
A gusty westerly gradient will continue on Saturday as low
pressure continues to exit the Canadian Maritimes. Some upslope
rain and snow showers may fall in the higher peaks during the
morning, but the theme for the day will be cooler and drier air
entering the region. Daytime highs will mainly be in the 50s,
but some lower 60s remain possible over the southern downslope
Have gone below most guidance with surface dew points for
Saturday. Using Bufkit, lower dew points will likely mix down
from above.This is also shown in the GYX probabilistic data
plots with a large variation of possible dew points expected
tomorrow. Fuels are wet right now, otherwise the combination of
low relative humidities and wind gusts in the 20 to 30 mph
range would lead to elevated fire weather conditions.
Clouds will increase Saturday night as a frontal system
approaches from the northwest. 12Z guidance in relatively good
agreement bringing scattered showers to western portions of the
region by late at night.
.LONG TERM /SUNDAY THROUGH FRIDAY/...
An active pattern is expected to continue in the long term portion
of the forecast with 2 or 3 more chances of significant rain. On
Sunday a weak cold front will drop south from Canada and stall
just south of the area Sunday Afternoon and into Monday. The
front will be rather moisture starved with just a chance of a
few showers with it Sunday morning. Behind the front high
pressure will briefly build south and give rather pleasant
conditions into Monday. Low pressure will develop to our west
and move east along the stalled frontal boundary. Models hint at
a coastal redevelopment although they keep the coastal feature
rather weak. Expect an area of rain associated with this low to
arrive late Monday into Tuesday. After a brief break later
Tuesday and Tuesday Night, another low will rapidly move
Northeast on Wednesday resulting in another round of rain during
the day. The low will be east of the area on Thursday but a
cyclonic flow will keep the threat of lingering showers over
eastern and mountain areas. Weak high pressure builds in for
Friday as another low pressure system organizes off the SE
coast. That system could affect the region just beyond the long
range period...next Friday Night.
The global models are in general agreement with the synoptic
features for next week but are slightly different on the timing of
these. For example the GFS brings rain over the region Monday
Afternoon while the ECMWF holds the rain off until Monday Night.
For the Wednesday system the GFS is further south with the low
therefore keeping the heaviest precipitation to our south, while
the ECMWF brings the low into the Gulf of Maine with more rainfall
over the area. For the late week system the GFS brings the rain
in Friday afternoon while the ECMWF holds it off until Friday
Have started with the NBM but based on the above discussion,
lowered pops in between systems on Monday and Thursday Night
into Friday. Did keep chance pops going for Friday Afternoon.
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Short Term...MVFR conditions will continue over much of New
Hampshire with ceilings lowering as you head further to the
north and east in Maine this evening. Some patchy fog expected
over eastern sections as well. Conditions improve later tonight
and into Saturday and a period of shower activity. Windy
conditions expected through Saturday as a westerly gradient
Long Term...VFR to MVFR Sunday into Monday. Areas of IFR develop over
NH Monday afternoon and spread into Western Maine Monday night into
Tuesday as an area of rain moves over the area. More rain and IFR
conditions possible on Wednesday.
Short Term...Have extended SCAs through Saturday as a strong westerly
gradient will continue with low pressure exiting through the
Canadian Maritimes. This hazard may need to be extended in time.
Long Term...Currently wind and waves are forecast to stay below SCA
levels through the long range period. However it would not be too
surprising if winds and seas both approach SCA levels Monday Night
into Tuesday as low pressure crosses the region.
MARINE...Small Craft Advisory from 6 AM to 6 PM EDT Saturday for ANZ153.
Small Craft Advisory until 6 PM EDT Saturday for ANZ150>152-
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
624 PM CDT Fri Apr 30 2021
251 PM CDT
Through Saturday night...
Breezy northeast winds across northeast Illinois and northwest
Indiana will continue to gradually ease with time this afternoon
as high pressure builds southward. An splotchy area of rather
persistent mid-level cloud cover is gradually building east across
southern Iowa, and this is likely represents the eastern terminus
of increasing warm advection around 850-700 mb ahead of the next
shortwave disturbance. This will continue to spread east into our
region through the late evening hours. Outside of some temporarily
increased mid-level cloud cover, not expecting any precipitation
with any parcels lifted from 700 mb capped off quickly by a pretty
stout subsidence inversion just under 500 mb. Another wave looks
to approach northern Illinois on Saturday morning, and this one
may overlap with somewhat better mid-level moisture to possibly
squeeze out a few sprinkles.
The main weather story for tomorrow will be the wind, as well as a
very elevated to near-critical fire danger, mainly for locales
north of I-80. For additional fire weather details, please see the
Fire Weather discussion below. Regarding the wind gust potential:
a notable low-level mass response is noted in model guidance, with
advertised 850 mb winds nearing 50 kts near the Illinois/Wisconsin
state line, peaking right around midday into the early afternoon.
While the morning hours will likely feature briefly increased
cloud cover, things should transition to more mostly sunny/partly
cloudy, which should allow us to more efficiently mix towards 850
mb. Our mixing potential will likely be capped off by a warm nose
just under 800 mb, but it still looks like we`ll be able to reach
into a good portion of this 45-50 kt flow. Combined this with a
broad region of persistent (and increasing) pressure falls through
the day, and the thinking is that winds may have the potential to
overperform some of the model guidance here. As a result, elected
to hoist a Wind Advisory for essentially our I-80 and north
locales for tomorrow afternoon. Could envision this advisory
needing to be expanded Winds should ease after sunset tomorrow.
There are currently no strong signs that surface-based parcels
will be able to meaningfully breach their LFCs tomorrow afternoon
with the approach of yet another shortwave, although runs of the
extended RAP are getting close. Should precipitation develop (<10%
chance right now), they`d certainly be gusty wind producers given
the dry sub-cloud layer and aforementioned stout flow through the
low-mid level column.
Southwesterly breezes will persist through Saturday night which
will help to hold overnight temperatures up a bit.
207 PM CDT
Sunday through Friday...
Sunday looks similar to Saturday with breezy (but not as windy)
southwest winds and highs in the lower 80s. Upper-level clouds will
increase during the evening and especially overnight into Monday as
a broad/baggy low pressure system develops over the Southern Plains
and starts pumping low- to mid-level moisture into the Great Lakes.
As the low drifts northeast Monday and Tuesday, chances for
precipitation will increase with disorganized episodes of showers
and perhaps a thunderstorm or two. Many hours will be dry (but still
decidedly cloudy), and areawide precipitation amounts less than an
inch look more likely than not. Temperatures Monday should top off
in the lower 70s, with Tuesday cooler and in the lower 60s.
As the low departs by the middle of the week, ensemble model
guidance exhibits a robust signal in a cooldown with high and low
temperatures settling into the lower 60s and lower 40s,
respectively. With a weak pressure gradient expected to be in place,
daily lake breezes appear likely keeping shoreline locations cooler.
Afternoon clouds or showers may become the norm toward the end of
the week as broad upper-level northwesterly flow prevails.
251 PM CDT
Elevated to near-critical fire danger is expected to develop on
Saturday afternoon due to the combination of very strong and gusty
southwest winds, warm temperatures, and low relative humidity
values. There remains some degree of uncertainty regarding how low
RH values may fall during the afternoon, with dewpoints currently
expected to slowly increase during the afternoon. The current
forecast will advertise minimum afternoon relative humidity values
as low as 25-30 percent north and west of I-55 with temperatures
rising into the lower 80s. One of the limiting factors is the
overall susceptibility of fuels across this part of the forecast
area. While little to no rain fell during the previous event,
calls to area fire partners indicate that green-up is a limiting
factor with fuels not as dry and receptive as they had been. As a
result of this, we have elected to refrain from issuing a Fire
Weather Watch, but will note that given the expected very windy
conditions, that any fires that do develop tomorrow will have the
potential to spread rapidly.
For the 00Z TAFs...
624 PM...Only forecast concern this period are very strong/gusty
southwest winds Saturday.
Easterly winds early this evening will become southeast by
mid/late evening with speeds generally under 10kts. Winds will
turn more southerly in the early morning hours and speeds will
likely increase into the 10-15kt range with some higher gusts
before sunrise. Speeds and gusts will quickly increase after
sunrise with gusts into the lower 30kt range mid/late Saturday
morning. Gusts will continue to increase into the 35-40kt range
Saturday afternoon. Wind directions during this time will slowly
turn more southwesterly. Speeds and gusts will diminish some with
sunset Saturday evening with gusts into the mid 20kt range still
expected Saturday evening. Speeds may diminish further into early
Sunday morning with the potential for low level wind shear later
Saturday night. cms
251 PM CDT
The previous Gale Watch has been converted to a Gale Warning for
the Illinois and Indiana nearshore waters, starting early Saturday
morning and into the early evening hours. Southwesterly gales to
40 kt (possibly briefly to 45 kt during the afternoon hours) are
expected during this time period.
Saturday to 7 PM Saturday.
LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...7 AM
Saturday to 10 PM Saturday.
Small Craft Advisory...IN nearshore waters until 7 PM Friday.
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...Updated Aviation Forecast Discussion...
Issued at 338 PM CDT Fri Apr 30 2021
Today and Tomorrow:
Another agreeable Spring day out there today. Perhaps even more
agreeable than yesterday with temperatures reading a couple of
degrees warmer and much calmer winds. Winds will begin to increase
tonight near midnight as a surface low develops over North
Dakota. The resultant tightening of the pressure gradient will
lead to overnight winds around 10 to 15 mph with an occasional
gust up to 20 mph. The strong winds and mixing will result in low
temperatures in the mid 50s (overnight lows yesterday were in the
Winds Saturday will be quite strong at 20 to 25 mph with gusts up
to 35 mph. Each updated run of the HRRR and RAP results in higher
guidance for surface winds. Strong warm air advection will result
in most of the forecast area reaching 90 degrees. The max
temperature record may be in reach for Omaha (93 degrees). The
hottest temperatures are expected along the Nebraska/South Dakota
border. Due to warm temperatures, strong winds, and critical
fuels, there will be a very high fire danger. Minimum relative
humidity values in the afternoon are expect to be in the 20 to
Sunday and Monday:
A cold front is expected to move through the area Sunday
afternoon. Sunday will be another pleasant day until the front
passes. Compared to 24 hours ago, the front has slowed a bit so
it`s probable the entire forecast area observes another 80 degree
day. That said, the persistent southerly winds should lead to dew
point temperatures reaching 60 degrees, at least in southeast
Nebraska. It could be a bit sticky in that area.
Weak lift associated with the front will lead to a good chance
for light rain starting Sunday afternoon. Rain chances will
continue into Monday morning as a weak upper level shortwave
moves through the northern Plains. Despite CAPE values near 1500
J/kg, severe weather won`t be much of a concern as shear will be
The cold front will lead to much cooler temperatures on Monday.
Precipitation could linger into the mid day. Either way, it will
be a damp, gray day with high temperatures reaching the mid 60s.
Tuesday through Thursday:
Troughing and a series of shortwaves will result in a few chances
of rain and temperatures near the climatic normal. This time of
year, thunderstorms are certainly in the realm of possibility.
With current guidance, best guess would be Wednesday evening for
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 609 PM CDT Fri Apr 30 2021
VFR conditions will prevail through the period.
Area Forecast Discussion
National Weather Service Reno NV
104 PM PDT Fri Apr 30 2021
A passing cold front will bring cooler temperatures along with gusty
winds and a few showers and thunderstorms this weekend. High
pressure will rebuild over the region next week leading to well
above normal temperatures and minimal precipitation chances.
* Primary changes were to increase probabilities for showers and t-
storms Sat afternoon and night, along with slight increases in
winds both Saturday and Sunday.
* Passing cold front will bring a variety of spring-like weather to
the region this weekend. First up are increased winds both days.
Nothing overly menacing but enough wind to result in travel
impacts for wind prone roads and choppy water on area lakes. Some
fire weather concerns too - see discussion below. ECMWF EPS and
NBM guidance hits Saturday afternoon as the breeziest with
southwest winds getting into that 30-40 mph zone for many areas.
Winds switch to NW on Sunday so that focuses the strongest winds
in the E Sierra valleys and along Highway 95. Maybe some blowing
dust here and there too.
* Latest models including the NAM3 and HRRR are increasing
confidence in seeing showers, t-storms Saturday afternoon, night,
and possibly into early Sunday morning. Respectable instability
coupled with frontal lift. Latest HREF t-storm probabilities keep
most activity north of Highway 50, with even up to a 4/10 chance
of a storm near RNO/NFL Saturday evening with higher values to the
north. Typical t-storm impacts expected - brief heavy rains,
pellets, gusty winds, and lightning. Showers possible into the E
Sierra early Sunday morning per NAM3 but instability appears
insufficient for t-storms.
* Quick shot of cool air on Sunday is followed by a decent warming
trend into mid to late next week. Temps could get back up to where
they were yesterday and today by next Wednesday, per NBM guidance.
Some signs of a cool down in EPS guidance late next week with
another trough working into the region. But big spread in temps
indicating uncertainties regarding trough`s position/anomaly.
Nearly all EPS members do keep this a dry feature but do increase
winds Thursday or Friday. Most ensembles keep any light precip out
of our area until early the following week when a broader trough
attempts to set up over the west.
Widespread VFR conditions today with scattered to broken high
clouds. Typical afternoon SW-W winds from approximately 21-03z
with peak gusts 20-25 kts.
A frontal boundary moving through northern Nevada Saturday will
bring slightly stronger W-NW winds with gusts to 30 kts possible
for terminal sites. FL100 winds aren`t overly strong - around
20-25 kts, but turbulence across the Sierra is still probable.
This front will bring scattered showers in the late afternoon to
overnight hours for areas near the Oregon/Idaho border south into
central and eastern Nevada. A few thunderstorms are possible as
well Saturday afternoon and early evening, with the highest
chances across northern Nevada into north-central Nevada (20-25%
chance). The primary focus for showers/storms will be north of
US-50 and east of US-395/I-580. Bases should remain VFR, though
periods of terrain obscuration are certainly possible.
Breezy north winds to follow on Sunday, with most terminal sites
peaking at 20-25 kts. Those that favor north winds, such as KHTH,
KBIH, and KTPH could see stronger winds of 35 kts in the afternoon
and early evening. -Dawn
Dry and breezy Saturday with periods of critical conditions
expected in the afternoon into early evening. The areas of concern
at this point are the Lahontan Basin, Sierra Front, Southern
Sierra Front, and Southern Mono County. Wind gusts will primarily
be in the 25-35 mph range (locally to 40 mph) with minimum RH
dropping down into the single digits to low teens. Most areas are
in green-up, but those that have extensive dry fine fuels without
green-up should be particularly cautious. Breezy north winds to
follow Sunday, but luckily RH will also be increasing to the
15-20% range. At this point, we are not planning on issuing any
watches or warnings based on the fuels intel we have.
The other concern are chances for thunderstorms Saturday afternoon
and early evening. These will be isolated in nature and along with
scattered showers, so concerns for major fire outbreaks are quite
low. The highest thunderstorm chances are across northern Nevada
into north-central Nevada (20-25% chance), with shower potential for
areas north of US-50 and east of US-395/I-580 into the night.
Wetting rains are possible, but will be spotty in nature with the
highest chances in the West Central Nevada Basin and Range eastward.
NV...Lake Wind Advisory from 2 PM to 11 PM PDT Saturday for Pyramid
Lake in NVZ004.
For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Shreveport LA
958 PM CDT Fri Apr 30 2021
A shallow wedge of dry air continues to backdoor SW into E
TX/WCntrl LA this evening, indicative of the lifting cigs farther
to the ENE over N LA/SW AR. Meanwhile, some patchy -DZ/-RA has
lingered this evening over the Wrn sections of E TX, where the
deeper moisture profile resides ahead of the closed upper low
spinning over Nrn old MX. This low level dry advection remains
progged to continue advecting SW across much of our E TX counties
through a portions of the overnight hours, before low level winds
begin to veer more SE late. While this has resulted in some
thinning over the elevated cigs as well, this will not last long
as ongoing convection over the TX Hill Country continues to expand
NNE across Cntrl and ECntrl TX overnight, resulting in thickening
AC cigs over E TX before eventually spreading into portions of
Wrn LA/SW AR late. The latest runs of the HRRR as well as the new
00Z NAM suggest that areas of -RA may spread into the far WSW
sections of E TX by/just prior to daybreak Saturday.
Have lowered pops to low chance pops for these areas, but dropped
mention of thunder given the stable air mass in place, while also
lowering pops to slight chance across the remainder of E TX. Did
make some adjustments to pops Saturday, maintaining likely pops
over Deep E TX in the morning although QPF amounts will remain
quite light, given the fact that this -RA will be encountering a
denser lyr of drier air as it enters the region. Thus, have
lowered pops a bit farther E and delayed mention of thunder
(isolated at best) until the afternoon, with the air mass
remaining relatively stable through the day. Only minor tweaks to
the forecast min temps were needed tonight, before the air mass
begins to modify Saturday with the return SErly low level flow. Deeper
convection is expected to continue developing through Saturday evening
over Cntrl and SE TX, ahead of the slowly NE ejecting upper low into
SW TX, with the convection expected to overspread much of the region
late Saturday night.
Zone update already out...grids will be available shortly.
.PREV DISCUSSION... /issued 640 PM CDT Fri Apr 30 2021/
VFR conditions will slowly continue to build SW across Wrn LA and
into E TX this evening, as drier air deepens as it backdoors SW in
wake of a weak cold fropa which has shifted S to near the SE TX/S
LA coasts. However, IFR/low MVFR cigs will persist across much of
E TX this evening, with areas of -DZ possible this evening across
the GGG/TYR terminals before cigs slowly lift. While a return to
VFR conditions is expected at GGG later tonight, IFR/low MVFR
cigs should linger at TYR/LFK, before these lower cigs begin to
return to the NNE across E TX from late morning through the
afternoon. Areas of -RA are expected to develop later tonight
across the TX Hill Country into SE TX, before eventually spreading
NE into portions of E TX by mid to late morning. However, this -RA
should not affect vsbys much, but have added mention in at the E
TX terminals, before diminishing by early to mid afternoon.
However, this will result in an increase in low AC cigs over much
of the area, with a cu field developing by afternoon and it begins
to spread back N in wake of the washed out front, with MVFR cigs
returning to portions of SW AR/Wrn LA during the evening. Light
ENE or Lt/Vrb winds tonight will become SSE 5-10kts after 15Z.
.PRELIMINARY POINT TEMPS/POPS...
SHV 62 76 65 80 / 10 30 80 80
MLU 59 78 64 78 / 5 20 60 90
DEQ 57 76 62 77 / 10 30 70 90
TXK 59 77 65 78 / 10 30 70 90
ELD 58 78 62 78 / 5 20 60 90
TYR 62 76 65 81 / 20 50 80 50
GGG 61 75 64 80 / 20 40 80 70
LFK 65 76 65 82 / 30 60 80 50
Area Forecast Discussion
National Weather Service Topeka KS
559 PM CDT Fri Apr 30 2021
Issued at 345 PM CDT Fri Apr 30 2021
Look for a pleasant weekend with the threat for showers and
storms growing by Sunday afternoon/evening and lasting through
1. Great Weekend Weather:
If you are reading this before sunset today, go outside and enjoy
this beautiful afternoon. A blocking pattern currently in place
across the central and western CONUS breaks down over the next 48
hours, but not before gracing the region with several days of
gorgeous springtime weather. Saturday will be breezier than today as
the surface ridge slides eastward and the pressure gradient tightens
over the region. Gusts on Saturday will push 30 to 35 mph from the
SSW, especially in north-central Kansas. Highs though will push into
the low to mid 80s, warmest towards north-central Kansas. Clouds
and dewpoints increase Saturday afternoon and evening as return
flow surges northward from the Gulf, setting the stage for an
increased threat for showers and storms on Sunday.
2. Unsettled Start to the Week
The cutoff low over the Southern Plains ejects northeastward into
the Lower Mississippi River Valley during the day on Sunday, with
height falls also noted ahead the next trough diving southeastward
over the Intermountain West. This northern stream trough ushers a
cold front southeastward on Sunday as well. We may find ourselves
sandwiched between the two primary regions of precipitation to the
northwest and southeast on Sunday, though with increased low-level
moisture and weak winds aloft, we may see some widely scattered
pulse showers and storms given the 1000+ J/kg of MLCAPE but
minimal effective shear on the NAM forecast soundings. The lack
of forcing will be the key limiter for precipitation, with
mesoscale subsidence off the system to the south potentially
canceling out the synoptic height falls upstream of the region.
By Sunday night, the cold front should be knocking on our doorstep
and slide through the region during the overnight hours and into
Monday morning. The guidance diverges how the front will behave as
a lee cyclone comes off the southern High Plains, but given the
GFS`s fast bias with the system last week, have trended more
towards the slower/wetter EC solutions/NBM for PoPs into Tuesday,
which results in showers lingering through the day, departing
Tuesday night. Steeper mid-level lapse rates could result in a few
stronger storms with the passage of the boundary, but confidence
in severe weather is not terribly high unless the front on Monday
3. Pleasant Middle to End to the Week
Broad cyclonic flow persists in the wake of our early week
convection, which will keep temperatures seasonal with periods of
sun and clouds. The medium to longer range guidance shows a few
potential disturbances working through during this time, thus have
maintained some slight chance PoPs into the end of the forecast
.AVIATION...(For the 00Z TAFS through 00Z Sunday)
Issued at 559 PM CDT Fri Apr 30 2021
A dry airmass and lack of forcing is expected to keep VFR
conditions in place. Forecast soundings from the RAP and NAM show
a nocturnal inversion with 30KT to 40KT at the top of the
inversion late tonight. Surface winds shouldn`t completely go calm
but they could drop off enough in the river valley for some LLWS
at TOP and MHK. And MOS guidance shows surface winds of 5KT to
7KT at FOE, which may be more marginal but will go ahead and
mention some LLWS for this terminal as well. The strong pressure
gradient will lead to gusty surface winds through the day
Issued at 345 PM CDT Fri Apr 30 2021
Elevated fire danger is expected across a portion of
the area on Saturday. A strong pressure gradient will lead to
sustained southwest winds of 20-25 mph and gusts of 30-35 mph
through the day. Deep mixing and temperatures warming into the 80s
will lead to afternoon relative humidity values of 20-30 percent,
lowest across north-central Kansas. The combination of strong
winds and low RH will create very high fire danger mainly along
and west of a line from Hiawatha to Abilene. Low-level moisture
increases in east central Kansas by Saturday afternoon which
should limit fire danger in this area.