Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/17/20
Area Forecast Discussion
National Weather Service La Crosse WI
1010 PM CDT Thu Apr 16 2020
.SHORT TERM...(This evening through Friday)
Issued at 302 PM CDT Thu Apr 16 2020
Strong frontogenetic snow band remains mainly to the south
overnight. Will be monitoring for a some very light snow in
southernmost Grant county and parts of northeast Iowa. Low-levels
will be dry so hydrometeors will need to work through that layer.
Friday afternoon is another deeper mixing day and thus have
increased winds a bit more than previous forecast with 15-20 mph
gusts. Model guidance has been consistently underforecasting the
winds in these deeper mixed regimes. Friday afternoon we mix through
about 800 mb, with an inverted-V sounding with some minor positive
CAPE seen aloft. This airmass is showing its hand a bit currently
over the ND/Canadian border per GOES imagery with enhanced cellular
convection and a few ground reports of -SHSN. So, have decided to
add some sprinkles for now Friday afternoon as the inverted-V dry
layer will need to be overcome to get some rain showers.
.LONG TERM...(Friday night through Thursday)
Issued at 302 PM CDT Thu Apr 16 2020
Friday night...the shortwave trough will be shifting to the east
and any sprinkles/flurries should be on the decrease. The h85
Thermal trough will transition to a thermal ridge (around +3 deg
C) by 18Z with southwest winds on the increase 15 to 30kts. H85
temperatures warm into the upper 50s and lower 60s for Saturday.
The cold front sweeps through Saturday night with cold air
advection increasing. A look at the forecast soundings show a few
of the models saturate the column with some light rain Saturday
night or a rain snow mix later with the cold air deepening. For
now our blends are still dry, but something to watch as we may
have to add some pops. Boosted winds from the southwest Saturday
and from the northwest Sunday mainly 15-21Z. Surface temperatures
will drop over 10 degrees from Saturday with highs in the 40s to
lower 50s.
Warming occurs ahead of next cold front Monday with highs in the 50s
to lower 60s. The brunt of the cooling occurs to our northeast with
highs in the 60s Tuesday. The flow becomes a little more zonal with
a chance for a light rain with highs in the 60s Wednesday and
Thursday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1005 PM CDT Thu Apr 16 2020
Plenty of mid/high level clouds for the rest of tonight as a
system slides by to our south. A subtle surface trough dropping
into the area during the day Friday will serve as the focus for an
uptick in afternoon VFR stratocu. With steep afternoon lapse
rates, will see a small amount of diurnal instability that may
prove adequate for some sprinkles. Latest RAP soundings show a
deeper cloud layer, so recent model trends seem to favor the
possibility of at least a few sprinkles. Will continue to monitor
trends, but have kept TAFs dry for now given coverage uncertainty.
Light south to southwest winds the rest of tonight will shift to
the west on Friday, increasing to around 10 to 15 knots during the
afternoon.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Baumgardt
LONG TERM...Zapotocny
AVIATION...Kurz
Area Forecast Discussion
National Weather Service Bismarck ND
842 PM CDT Thu Apr 16 2020
.UPDATE...
Issued at 842 PM CDT Thu Apr 16 2020
Weakening trends in the radar reflectivities across the north
continues and fully expect a quick end to them as sunset has just
or will soon occur. However, 850mb-700mb moisture/clouds will
linger through 06z with clearing conditions commencing thereafter
as the last of the shortwaves tonight shifts towards the southern
border 06z-09z. Current gridded forecast on track tonight.
UPDATE Issued at 532 PM CDT Thu Apr 16 2020
Only updates were to increase sky coverage to mostly cloudy/cloudy
across the north while blending the PoPs through 03z with the
high resolution ARW West and NMM West Composite reflectivities
and then limiting PoPs to an isolated (20 percent) mention. Weak
shortwave trough over northern North Dakota with another shortwave
seen on water vapor in northeastern Montana shifting south with
time. Isolated showers driven by afternoon heating/steep low level
lapse rates; very little if any large scale ascent/forcing by the
aforementioned shortwaves. Expect a gradual decrease in clouds
overnight across the north with showers dissipating shortly after
sunset.
&&
.SHORT TERM...(Tonight through Friday)
Issued at 231 PM CDT Thu Apr 16 2020
The short term forecast is highlighted by warm, breezy, and dry
conditions on Friday before a cold front moves in from the
northwest Friday night.
Tonight, mid-level height gradients will tighten over the Northern
Plains with increasing northwest flow. A surface low will deepen
over central Canada through Friday ahead of a stronger mid-level
embedded shortwave trough. North Dakota will be placed in the
broad warm sector of this low with warm and dry southwest low
level flow overtaking the region.
Tomorrow the atmospheric column should be characterized by deep
boundary layer mixing with downsloping winds at the surface and
southwest flow aiding in drying conditions out. Using MOS
guidance for temperatures, we brought highs into the mid-upper 50s
though sites reaching 60 will certainly be possible. Sustained
winds of 15-25 mph are expected with RAP guidance blended into the
given NBM to produce surface dew points down to 15 F, which drops
minimum relative humidities into the 20s if not down to the upper
teens in some isolated areas of west/central North Dakota. This
should produce a near critical fire weather day with the worst of
the conditions marginal/transient enough at the time to preclude
headlines.
.LONG TERM...(Friday night through Thursday)
Issued at 231 PM CDT Thu Apr 16 2020
Slight chances for precipitation will persist in the forecast
through the weekend before temperatures warm early through the
middle of next week.
A cold front arrives from the northwest Friday night with cooler
temperatures expected on Saturday. Beginning in this period mean
northwest flow aloft takes hold through the weekend with a series
of embedded shortwave trough passages expected along with chances
for precipitation. Predictability in timing/location remains
difficult given the broad forcing mechanism but with continuous
cyclonic flow aloft and steep low level lapse rates there is
enough of a probability to add low chances of showers in this
forecast shift. Based off 12Z GFS/ECMWF mid-level height falls
and enough ensemble QPF agreement, the greatest chances should be
focused in the early Saturday morning through early Sunday
morning period, though there is certainly room for flexibility on
either end of that time frame.
Going into next week, model consensus continues to point towards a
ridge building over the Northern Rockies with low-mid level warm
air advection pushing into the Northern Plains. NBM probabilities
show temperatures reaching the low 70s will be possible in the
Tuesday-Wednesday time frame.
Outside of the chance of showers this weekend, the overall
forecast is mostly dry with the height rise pattern expected next
week. Deterministic models are in decent agreement in developing a
trough through the region by late next week which does show up in
the NBM members with slight chances of precipitation produced on
Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 532 PM CDT Thu Apr 16 2020
Although VFR cigs/vsbys will continue this taf period, isolated
showers are possible through 03z Friday across the northern
terminals of KXWA/KMOT with cigs around 6kft to 7kft. Any shower
could produce a brief wind gust to 20kt-25kt. Otherwise, clouds
will gradually decrease tonight with mostly sunny and breezy
conditions Friday. Southwest winds developing out ahead of a cold
front dropping south from the southern Canadians will result in
wind speeds of between 15 mph and 25 mph across the terminals.
Sct/Bkn highs clouds will begin developing across the northern
terminals Friday afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...AE
LONG TERM...AE
AVIATION...KS
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
607 PM MDT Thu Apr 16 2020
.AVIATION...00Z TAF CYCLE
Westerly winds will generally subside over the next few hours, but
some occasional gustiness may return at ELP later this evening.
The RAP suggests 850 mb winds will trend upwards again after
sundown through to about 08Z. Otherwise, expect VFR conditions
with increasing high clouds overnight, with SCT-BKN200 common by
midnight, especially south of TCS. We will see brief clearing in
the morning, followed by another batch of high clouds towards the
afternoon. A few afternoon gusts may be up to 25 knots again
tomorrow (Fri).
25-Hardiman
&&
.PREV DISCUSSION...259 PM MDT Thu Apr 16 2020...
.SYNOPSIS...
Looks like the Borderland will remain dry and occasionally windy;
in other words much like a normal April. A persistent dry west
flow aloft is the main culprit. This flow will bring several small
Pacific storms across northern New Mexico over the next week. The
first one will move through the area Friday, bringing a few
clouds and a breezy afternoon. The next one will move across
Saturday, bringing another breezy afternoon to the Borderland. The
final system will move in Tuesday. With the system being a bit
stronger, winds will also be stronger, though probably not up to
wind advisory strength. Temperatures will remain at or above
normal.
&&
.DISCUSSION...
.SHORT TERM...Tonight and Friday...
The Borderland is currently under dry, upper-level zonal flow, as
seen clearly on GOES water vapor satellite imagery. A low off the
coast of CA will push east overnight, transitioning our flow to
southwest as modest ridging builds over the region for Friday. This
will bring in a brief period of subtropical moisture manifesting in
high-level cloud cover, before being pushed east by Friday
afternoon. However, additional high clouds will move in from the
west with the ridge by late Friday afternoon.
At the surface, a low over NE NM is pushing south this evening. This
low has increased the pressure gradient over the Borderland this
afternoon, causing breezy conditions. This low will continue to drop
south through the night, which may keep our winds elevated after
dark, but the nocturnal inversion will take over, dropping winds to
light by morning. An attendant cold front will only make it to the
east slopes of the Sacramento Mountains by morning before the cold
airmass is pushed east by W/SW return flow under the ridge on
Friday. This will allow temperatures on Friday to be similar to
Thursday`s highs, with several lowland locations reaching into the
80s. Winds become breezy once again late Friday afternoon.
&&
.LONG TERM...Friday night through Thursday...
Our typical late spring weather should continue through this
forecast period. Dry west to southwest flow aloft will dominate
the period, with several relatively weak Pacific systems sweeping
across the area. The first system, which moved in Friday, will
exit the area early Saturday. This will bring some clouds in
Saturday along with breezy afternoon winds. Another small upper
low will track northern New Mexico Sunday morning, again helping
produce a breezy Sunday afternoon.
A somewhat larger Pacific frontal system moves in for Monday and
Tuesday. Expect some clouds into the area Monday and some more
afternoon breezes. The upper low then moves across central New
Mexico Tuesday morning. Normally this would be ill-timed for a
windy afternoon on Tuesday. However, both GFS and ECMWF show a
secondary upper low quickly moving Tuesday afternoon behind the
first low. This will help increase winds into windy category,
though for now it looks to remain below advisory criteria. Kept
token POPs in for the mountains Tuesday/Tuesday night. Will have
to watch this scene for possible upgrades. Models do show some
decent instability on Tuesday, though most of it is north of our
CWA.
Wednesday and Thursday look fairly quiet. Perhaps windy again on
Thursday as upper trough passes across Colorado and northern New
Mexico. H85 temps show strong warm advection Thursday and GFS MOS
shows lowland temps approaching 90 degrees. El Paso`s average
first 90 degree reading of the season is April 29, so if we hit 90
by next Thursday, that would be about a week ahead of schedule.
&&
.AVIATION...VFR conditions through the TAF period. This afternoon the upper
level pattern shifts to southwest flow, which will bring in some
high clouds over the forecast area tonight, before shifting out of
the region by Friday afternoon. A surface low will push south
today, bringing gusty westerly winds this afternoon in the
10-15 G20-25KT range. Winds will decrease gradually after dark to
less than 10 knots through morning. Wind becomes gusty once again
Friday afternoon.
&&
.FIRE WEATHER...
Dry and breezy conditions continue through the next week causing
periods of fire weather concerns, especially on Saturday and again
on Tuesday. However, with the afternoon min RH generally in the
teens, especially in the lowlands, fire weather concerns will be
elevated regardless.
Max RH recovery overnight will range from 30 percent in the lowlands
to 40 percent in the mountain zones. Friday will see breezy winds by
late afternoon ahead of an approaching upper level storm system. Min
RH will be in the teens, but wind will remain below critical levels.
The upper level storm system will provide breezy to windy conditions
in the afternoon on Saturday, causing lowland locations to reach
critical to near critical fire weather conditions. Min RH`s on
Saturday will be around 10% in the lowlands and a little higher in
the mountains. Max vent rates will be excellent.
Sunday and Monday will provide breezy afternoons, but overall quiet
weather. On Tuesday, another storm system, albeit stronger than
Saturday`s system, will bring windy conditions again to the area. At
the same time min RH`s will continue to run near 10% in the lowlands
and near 20% percent in the mountains causing concern for red flag
conditions on Tuesday afternoon.
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 55 81 55 79 / 0 0 0 0
Sierra Blanca 52 77 49 78 / 0 0 0 0
Las Cruces 47 77 47 77 / 0 0 0 0
Alamogordo 49 74 49 78 / 0 0 0 0
Cloudcroft 37 56 32 53 / 0 0 0 0
Truth or Consequences 47 79 47 75 / 0 0 0 0
Silver City 42 69 41 67 / 0 0 0 0
Deming 41 78 44 76 / 0 0 0 0
Lordsburg 43 77 43 74 / 0 0 0 0
West El Paso Metro 55 81 54 79 / 0 0 0 0
Dell City 48 81 46 80 / 0 0 0 0
Fort Hancock 54 85 51 83 / 0 0 0 0
Loma Linda 51 76 50 74 / 0 0 0 0
Fabens 54 83 52 81 / 0 0 0 0
Santa Teresa 49 80 50 78 / 0 0 0 0
White Sands HQ 54 80 52 77 / 0 0 0 0
Jornada Range 47 78 41 75 / 0 0 0 0
Hatch 44 79 44 77 / 0 0 0 0
Columbus 49 81 46 78 / 0 0 0 0
Orogrande 48 79 49 77 / 0 0 0 0
Mayhill 38 69 39 67 / 0 0 0 0
Mescalero 39 67 39 64 / 0 0 0 0
Timberon 38 64 37 62 / 0 0 0 0
Winston 35 72 40 69 / 0 0 0 0
Hillsboro 42 77 44 73 / 0 0 0 0
Spaceport 43 77 41 75 / 0 0 0 0
Lake Roberts 36 71 39 68 / 0 0 0 0
Hurley 39 69 40 70 / 0 0 0 0
Cliff 36 77 32 70 / 0 0 0 0
Mule Creek 41 72 32 68 / 0 0 0 0
Faywood 41 74 41 70 / 0 0 0 0
Animas 42 79 43 77 / 0 0 0 0
Hachita 43 78 43 75 / 0 0 0 0
Antelope Wells 43 79 43 77 / 0 0 0 0
Cloverdale 44 72 42 71 / 0 0 0 0
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Grand Rapids MI
800 PM EDT Thu Apr 16 2020
LATEST UPDATE...
Update/Aviation
.SYNOPSIS...
Issued at 300 PM EDT Thu Apr 16 2020
- Light Snow showers this afternoon
- Snow mainly south of I-96 Friday
- Brief Warm up this weekend and cooler next week
&&
.UPDATE...
Issued at 800 PM EDT Thu Apr 16 2020
I continue to watch trends in the Hi Res models that come in
every hour and the 18z update to GFS and NAM for trends in how
much snow and were it will fall over our CWA Friday. There has
been a trend slightly north for amounts of snow. For example the
18z run of the HRRR had the snow water equivalent of 0.01 inch
line on the Kent/Barry County border by 10 am and and the .10 of
an inch line on the Barry Kalamazoo County lines. By 22z the .01
inch line is in northern Kent Count and the .10 was almost to
Grand Rapids. Similar trends are noted with the ECMWF 00z to 12z
runs and GFS too. I updated our grids to increase the
precipitation amounts slightly and push the precipitation farther
north. I also believe this will be mostly a snow event so I did
what I could to decrease the rain in our grids tomorrow afternoon.
I through about issuing an Winter Weather Advisory but on talking
about it with our other forecaster on shift tonight, we decided
even with a little more snow there would not be enough of a
driving impact to need a headline. That is mostly since the snow
will be falling during the day light hours and be heaviest during
the midday hours. That would make it hard to stick to road
surfaces.
&&
.DISCUSSION...(Today through next Wednesday)
Issued at 310 PM EDT Thu Apr 16 2020
-- Light Snow showers this afternoon --
Latest radar at 3 PM shows isolated snow showers moving through
central lower Michigan north of I 96 and East of US 131. These
showers have little to no accumulation associated with them and will
move quickly eastward as the weak trough these are associated with
continues to trek eastward. Any light showers will end late this
afternoon.
-- Snow mainly south of I-96 Friday --
A larger system will bring snowfall to Southern lower Michigan
tomorrow morning. The latest blend of higher res model guidance and
ensembles continues to indicate that light snow will develop very
late tonight and continue through Friday due to isentropic upglide
associated with a low pressure system moving ENE across the lower
Ohio valley region. The snow will develop during the early morning
hours Friday near to mainly south of I-96 and then continue across
that area through early to mid aftn Friday before moving out. The
period of highest accumulating snowfall will be during morning rush
hour along I 94 and I 96. A period of reduced visibility with slick
to icy roadways are a concern, especially I 94.
Snow accumulations range will be from around one to three inches
along and to south of the I-94 corridor with around an inch or less
along the I-96 corridor. Latest convective allowing models show this
solution. Locally higher amounts are possible though unlikely given
ground temperatures.
-- Brief Warm up this weekend and cooler next week --
Temperatures will remain cold through Saturday morning with
temperatures rising above normal briefly on Sunday. However this
will be short lived as the southwest flow of mild air shifts and a
northwest flow wind regime returns bringing colder then normal
temperatures through the middle of next week. Longer range ensembles
suggest temps may finally return to near normal by mid to late next
week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 800 PM EDT Thu Apr 16 2020
We get solid VFR evening around Southwest Michigan. The nearest
snow is over Iowa and extreme western Illinois at 745 pm this
evening. The snow should reach our I-94 TAF sites just prior to
12z and just after 12z for GRR and LAN. It`s questionable for the
snow to reach MKG but I put in the TAF even so. If the snow does
not reach MKG, MKG would more than likely stay VFR all day.
The snow will bring solid IFR to all of our I-94 TAF sites and
that would most likely be in the 15z to 18z time frame. The snow
will likely be moderate at times there. It may mix with rain just
before it ends during the late afternoon but for the most part
this will be an all snow event. Expect some clearing after 00z.
&&
.MARINE...
Issued at 300 PM EDT Thu Apr 16 2020
West winds will increase to around 10 to 20 kts today and result
in wave heights of up to around 4 feet. The winds will back to the
southwest this weekend and strengthen. The latest wave watch models
continue to show an increase of winds and waves this weekend which
will likely cause a small craft advisory to be needed.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...WDM
SYNOPSIS...Ceru
DISCUSSION...Ceru
AVIATION...WDM
MARINE...Ceru
Area Forecast Discussion
National Weather Service Lincoln IL
919 PM CDT Thu Apr 16 2020
.SYNOPSIS...
Issued at 250 PM CDT Thu Apr 16 2020
Wet weather will begin to move back into the region this evening,
overspreading central Illinois tonight. This will bring rain to
start, however expecting a change to heavy snowfall through the
overnight. The main band of snow is forecast to form across
northern Illinois, bringing upwards of 6 to 8 inches to many
locations through Friday morning. After this system exits Friday
evening, dry weather returns Saturday with temperatures climbing
back into the 50s.
&&
.UPDATE...
Issued at 915 PM CDT Thu Apr 16 2020
00Z HRRR and RAP updates this evening are showing similar
snowfall potential as the previous forecast, with only a slight
southward shift in the main snow band placement. Snow has even
mixed with the rain at Lincoln and Springfield earlier this
evening, however, a warm surge aloft will keep the primary rain-
snow line farther north of a line from near Rushville to northern
Champaign County. Macomb has been snowing for several hours
already, and western Fulton County has likely seen some light
accumulations so far. Rain should continue to transition to snow
across northern areas as the evening progresses. Impressive omega
in the cloud bearing layer will support some enhanced snowfall
rates between 10 pm and 4 am. While thundersnow is not likely,
some channels of slantwise instability/negative EPV just above a
layer of frontogenesis could allow for a clap of thunder or two.
Snowfall rates of 1 inch per hour, or even slightly higher, will
be possible in the 10 pm to 4 am window.
Snowfall accumulation will vary greatly over short distances in
this system, especially along the southern edge of the snowband.
Some northern portions of counties could see upwards of 6 inches
of snow, while southern portions of that county get less than an
inch.
We do not see enough evidence to alter the ongoing forecast, so
will keep the headlines and snowfall amounts intact. Updated
products will be sent shortly.
&&
.SHORT TERM...(This evening through Friday night)
ISSUED AT 250 PM CDT Thu Apr 16 2020
An early morning round of snowfall and light rain moved through
central and southeast Illinois, leaving behind moisture for clouds
to linger through today. With a weak boundary setup between the
I-72 and I-70 corridors today, temperatures ranged greatly across
the area. Across the northern CWA, highs only climbed into the low
40, with low 50s currently south of I-70. As this boundary slowly
lifts northward tonight, this will be the axis of main
precipitation development and snow accumulation. Precipitation
will begin as rainfall this evening, with temperatures above
freezing. However, as we head overnight, temps will drop to the
mid 30s and then to near freezing. This drop in temps will allow
precip to transition to snow overnight. With the boundary lifting
to the northern CWA, and near freezing temperatures, a
precipitation band will develop just to the north of this
boundary. This is where the pinpoint is expected for up to 8
inches of heavy, wet snowfall to occur. The main axis will develop
from MQB-PIA-PNT, and points northward, with a rapid decrease in
accumulations south of this line. Current model trend did drop
slightly with the track, however only 15-25 miles south at best.
With this track, still expecting the remaining locations of the
CWA, from Rushville- Lincoln-Danville and points south, to see
rain. This area will feature upwards of 0.75 inches of rain, with
amounts decreasing southward.
As the flattened upper level moves this wave out of the Midwest
Friday, rain will exit the region late afternoon. Another night of
colder temperatures arrives Friday night with temperatures
dropping to below freezing across much of the region, with the
far southeast CWA reaching freezing.
.LONG TERM...(Saturday through Thursday)
ISSUED AT 250 PM CDT Thu Apr 16 2020
Not much attention was paid to this part of the forecast period as
the upcoming snow storm and subsequent Winter Storm Warning was
the main concern. Drier weather returns Saturday, along with
the next warming trend across the Midwest. This warming trend will
continue through the end of the weekend and really ramp up into
next week. Looking ahead to a much warmer start to next week with
temps climbing back into the 60s to near 70 throughout the region
for much of next week.
Going towards the end of this weekend, a storm system will develop
across the southern Plains, and traverse through the se US. This
will see a deepening trend as moisture once again gets ingested
from the Gulf of Mexico through Sunday. Currently not expecting
much in the terms of rainfall, except some chances throughout
southern Illinois. Dry conditions prevail into next week, with the
next system to impact the entire area coming mid-week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 634 PM CDT Thu Apr 16 2020
A band of precipitation is already overspreading central IL from
the west, with SPI reporting rain before 00z/7pm. Rain will be the
primary initial precip type, but will quickly transition to snow.
Altona IL has already reported light snow, northwest of Peoria. So
the transition to snow is already starting in portions of west-
central IL. The transition to snow will be most notable at PIA
and BMI, where snow accumulation is expected. PIA could see up to
4-6" at the airport, with slushy accum of a few inches on the
travel surfaces. Further south expect SPI/DEC/CMI to see
primarily rain overnight. For areas that transition to snow, snow
will be heavy at times with heavy accumulations, especially at PIA.
MVFR and IFR ceilings will redevelop across the region, bottoming
out late tonight into early Friday as low pressure moves across
the region. North to northwest winds will set up behind the low
and precip will diminish late Friday morning. MVFR conditions will
likely linger Friday afternoon for at least a couple of hours if
not longer.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 10 AM CDT Friday for ILZ027>031-036.
Winter Weather Advisory until 10 AM CDT Friday for ILZ037-038.
&&
$$
UPDATE...Shimon
SYNOPSIS...Baker
SHORT TERM...Baker
LONG TERM...Baker
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Reno NV
629 PM PDT Thu Apr 16 2020
.UPDATE...
Showers and thunderstorms have formed farther north this evening,
with activity just north of I-80. However, most storms remain
near and west of the crest that far north. We are seeing showers
pop up along the western shores of Lake Tahoe, with better shower
and isolated thunderstorm coverage south of Tahoe through Mono
County. Have updated the forecast to reflect latest radar trends.
HRRR guidance suggests most storm activity will taper off around
sunset, which makes sense given diurnal heating is driving storms.
Better shower and thunderstorm coverage is anticipated Friday
afternoon/evening. Please see the previous discussion below for
additional details. -Dawn
&&
.PREVIOUS DISCUSSION... /Issued 255 PM PDT Thu Apr 16 2020/
SYNOPSIS...
Typical spring variability continues through the weekend and into
early next week. Expect cooler conditions for the next few days
as well as increased chances for showers and thunderstorms for the
Sierra this afternoon and Friday. The more widespread chances for
showers across the Sierra and western Nevada will occur Sunday
night into Monday.
SHORT TERM...
Temperatures are a bit cooler today after the passage of a cold
front overnight. The high temperatures will be typical for April and
be in the 50s to mid 60s for the region the next couple of days.
Several low pressure centers wobbling across the West will make for
an interesting forecast through the weekend. Upper level divergence
associated with the lows along with low-level convergence will
result in increased potential for showers and thunderstorms today
and Friday. Plan for showers south of Highway 50 today, with a 5-10%
chance of thunder. For Friday, the chance for showers expands across
the Tahoe Basin and western NV south of Highway 50 as a low off the
CA coast swings inland across southern CA and NV. Thunderstorm
progs continue to highlight anywhere from 10-20% in the Sierra,
so isolated thunderstorms were added across the Sierra northward
into the Tahoe basin for Friday afternoon/evening.
Primary concerns with any showers or thunderstorms that develop will
be the potential for lightning, hail, or brief pellet accumulations,
especially in the mountain areas. If you have outdoor plans or
travel plans in the Sierra, be aware for the potential of these
conditions and prepare accordingly. Any snow pellet or hail
accumulation on the mountain roads could lead to slick travel
conditions for brief periods of time.
As far as snow through Friday, snow levels will, for the most
part, remain above 8000 feet with the higher passes seeing up to
a few inches, mainly on Friday as the heaviest precipitation moves
into the Sierra.
On Saturday, the low will exit to the east and allow the next low
pressure system to drop into CA and NV. Plan for lingering light
afternoon showers in the Sierra Saturday afternoon and increasing
chances for showers across far northwestern NV Saturday night.
-Edan
LONG TERM...Sunday through next week...
The active spring pattern continues for Sunday and Monday of next
week as a ridge of high pressure centers itself off of the
British Columbia coast allowing a pair of weak low pressure
systems to impact the Sierra and western Nevada... one likely from
the north on Sunday and another from the west on Monday. Light
rain and high elevation snow showers are possible for areas
mainly north of I-80 Sunday morning, tapering off by late Sunday
afternoon/early evening, and then becoming more widespread on
Monday as the second low pushes through from the west undercutting
the ridge. Slight chances for thunderstorm activity were left in
the forecast during the day on Monday mainly across the eastern
Sierra from Alpine County south extending into Mineral County. We
are in that time of year when thunderstorm development is more
common with sufficient daytime heating and the presence of weak
upper level lows providing some instability. So, we will need to
keep monitoring the chances to see if we need to extend coverage
for Monday.
Leftover showers look to stick around for Mono and southern
Mineral counties early Tuesday before drying out by the afternoon
with shortwave ridging in place. Everywhere else can expect
scattered cloud cover and breezy northwest winds with high
temperatures in the upper 60s for western Nevada and 50s for the
Sierra. By Wednesday, west-northwest winds look to increase as
the pressure gradient tightens across the region in response to
low pressure towards the northeast and high pressure off the west
coast. Chances for showers return for late Wednesday into Thursday
focused for areas north of I-80 at this time as the broad area of
low pressure moves off to the east.
For the end of next week, confidence is increasing in a longwave
ridge moving in from the west bringing more stable conditions and
warmer temperatures to the region. However, take this scenario
with a grain of salt as the long term spring pattern in northern
Nevada and the Sierra could turn on a dime. -LaGuardia
AVIATION...
VFR conditions continue this afternoon with breezy northeast
winds for all area terminals besides for KMMH where brief MVFR
conditions and erratic winds are possible due to showers and
isolated thunderstorms.
Cloud cover increases over the Sierra late this afternoon
extending across the rest of the region tonight into Friday.
Chances for rain/pellet showers and isolated thunderstorms
increase for Friday afternoon/early evening expanding north from
the Tahoe Basin and into western Nevada from about Washoe Valley
south. Primary concerns with any showers or thunderstorms that develop will
be the potential for lightning, hail, or brief pellet
accumulations causing MVFR/IFR conditions at times. Mountain
obscuration can also be an issue during this time, especially for
the Sierra terminals.
Chances for isolated showers and breezy west-northwest winds
are possible for the weekend with the best chances for widespread
precipitation expected on Monday. -LaGuardia
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Las Vegas NV
247 PM PDT Thu Apr 16 2020
.SYNOPSIS...Increasing shower chances are expected across the
Sierra and southern Great Basin tonight before spreading across
the Mojave Desert on Friday along with isolated thunderstorms and
gusty outflow winds. Lingering showers remain possible Saturday
before drying out Sunday. Additional weak storm systems will
approach the region next week. Temperatures will hover within a
few degrees of average through the week ahead. &&
.Short Term...through Saturday.
Trough brushing the region to our northeast today has limited
moisture, and overall isn`t expected to impact the area much other
than some light rain/virga showers across south/central NV and Inyo
County and some breezy winds tonight. Best chances to see these
light/virga showers will be after ~00-03Z this afternoon with
best chances expected tonight. A weak frontal boundary will push
through Lincoln and northeast Clark overnight tonight bringing
some breezy northeast winds.
A cutoff low off the central CA coast will swing into SoCal by
Friday and bring slightly more moisture and added dynamics. This
will allow for increased coverage of light showers and isolated
thunderstorms mainly for areas north and west of the I-15 corridor
Friday. Best chances to see thunderstorms will be across San
Bernardino, southern Inyo, and along the Spring Mountains where the
better dynamics and instability are expected Friday afternoon. Still
anticipating light precipitation amounts with this system due to a
dry sub-cloud layer. Models are indicating that DCAPE values
around 500-1000 J/kg and bulk shear of 20-35 knots are possible
across parts of the Mojave Desert tomorrow afternoon. Where the
moisture and instability boundary sets up tomorrow, more organized
thunderstorms are possible and may produce gusty outflow
boundaries. The HRRR has already started to show these outflow
boundaries develop tomorrow along the higher terrain near Mountain
Pass and the Springs mountains, and may even push into the Las
Vegas Valley tomorrow afternoon. Besides outflow boundaries influencing
winds, expect breezy southwest winds to spread across the western
Mojave Desert, and lighter winds expected elsewhere. Since this
system will be warm, snow will be limited to mainly elevations
about 8000-9000 feet. Expected snow totals along the eastern
Sierra of 2-4 inches above 8000 feet and up to 5-7 inches along
the peaks.
As the cutoff low moves across the tri-state area overnight Friday,
another weak wave will move through the region Saturday, bringing
more slight chances of showers across Lincoln, Nye, Esmeralda, Inyo
and northern Mohave counties. Low end instability is possible mainly
across Lincoln County Saturday where isolated thunderstorms will be
possible. This wave will quickly shift eastward through Saturday,
leaving dry conditions by Saturday evening.
Long Term...Sunday through Wednesday.
Mostly zonal flow expected Sunday will break down as a weak piece of
energy moves through the northern NV, mainly increasing cloud cover
and bringing breezy southwest winds. Models have come together a
bit on timing and general place of the the next system early next
week with a trough digging into SoCal yet again on Monday. Though,
as this system progresses through Monday, models digress and
forecast confidence is still low on the placement and timing of the
potential precip chances Monday-Tuesday.
&&
.AVIATION...For McCarran...Easterly winds generally remaining below
10 knots through this afternoon. Winds will become light and variable
this evening. A push of northeast winds is expected to make it to
KLSV overnight tonight, but confidence is low these winds will make
it to KLAS. If they were to make it, expect winds up around 10 knots
between 020-050. Northeast winds are more likely to make it to KLAS
by between 16-17Z tomorrow morning, with some occasional gusts up to
15-20 knots through about 20Z. Thereafter, light easterly winds
expected through the rest of the afternoon. Distant showers and
thunderstorms are possible south and west of Las Vegas tomorrow,
which may produce gusty outflow winds which could impact the Daggett
corridor. SCT-BKN aoa 12 Kft expected through the forecast period.
For the rest of southern Nevada, northwest Arizona and southeast
California...Generally, diurnal winds expected to continue through
the early afternoon. Slight chances for vicinity showers near KBIH
tonight. Another window of vicinity showers/isolated thunderstorms
are possible tomorrow afternoon for KBIH and KDAG mainly between 18-
00Z. With any thunderstorms that develop, gusty outflow winds are
possible. Elsewhere, expect occasionally breezy north winds through
the morning to around 15-20 knots. With south to southwest winds in
the afternoon. SCT-BKN aoa 12 Kft expected through the forecast
period. &&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION/AVIATION...Kryston
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