Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/13/24
Area Forecast Discussion
National Weather Service Cheyenne WY
526 PM MDT Mon Aug 12 2024
.KEY MESSAGES...
- Scattered to numerous showers and thunderstorms are expected
to develop this afternoon. Storms will have the potential to
produce torrential rainfall, gusty winds, and isolated large
hail.
- An active pattern continues through the week ahead with near
normal temperatures and daily chances for afternoon and
evening showers and thunderstorms.
&&
.MESOSCALE...
Issued at 140 PM MDT Mon Aug 12 2024
Daytime insolation has allowed the atmosphere to begin to
percolate across portions of far southeast WY. 18Z RAP
mesoanalysis via SPC depicts steep lapse rates of 9 degrees C/km
in the H5-H7 lower levels, and effective bulk shear from 0-6km
between 30-45 knots along the stationary frontal boundary that
is presently draped on a north to south transect from the Front
Range to the North Laramie Range. Additionally, surface-based
CAPE of doing quite well in response to the daytime sunshine, as
integrated amounts of 1000-2500 J/kg from the I-25 corridor
toward the Sandhills of west-central NE exists. Unsurprisingly,
we have had Cu fields and agitated towering cumulus develop in
the past 1-2 hours along the South Laramie Range, with a couple
of strong thunderstorms initiating in the same area. PWATs are
in the 90-99th %ile so far today, with deep Theta-e moisture
advection being evidenced on the GOES-16 satellite imagery.
Southeast flow from the south and central Plains has kept the
low cloud cover near the CO/NE/KS border. In the next 1-2 hours,
expect more clearing across our cwa, with additional
thundershowers occurring across the I-80 corridor and east of
I-25. With the slow-moving convection being anticipated to
develop/continue soon, we will have increased chances for
isolated flooding ticking upwards this afternoon. Hi-res model
guidance does hint at multiple rounds of showers and
thunderstorms through this evening, and into the overnight
hours. Highest concern through the evening and overnight hours
is potential heavy rainfall accumulation in central and south NE
Panhandle.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 330 AM MDT Mon Aug 12 2024
After a brief break in the wet pattern yesterday, moisture is
returning to the area today with more widespread thunderstorm
activity expected this afternoon. GOES satellite water vapor channel
imagery shows that the shortwave that passed through the area
yesterday is now moving across the Dakotas. The subsident pocket of
dry air is shifting eastward also, with the driest air now in
central and eastern Nebraska. As the upper level ridge axis slowly
shifts east today, the flow aloft will shift from northwest to west
and subtly southwest, allowing for the monsoon moisture tap to open
up fully again. High cirrus and much better mid to upper level
moisture is already visible moving from southwest to northeast
across our area this morning. Meanwhile at the surface, we have a
weak surface high over the northern plains and a weak surface low
over southeast Colorado. East to southeast surface winds in between
these two features are pushing low level moisture back into the high
plains. Good radiative cooling ahead of the approaching cirrus deck
is resulting in fairly widespread fog forming along portions of the
I-80 corridor from the summit east towards Sidney. In the areas
where the fog coverage is highest (eastern Laramie, Kimball, and
Cheyenne counties), a Dense Fog Advisory has been issued through 9AM.
Heading into this afternoon, the return of moisture will set the
stage for a more active day of afternoon convection. By this
afternoon, both precipitable water and integrated water vapor
transport will be above the 90th percentile of climatology over much
of the area. The next vort-max aloft will arrive this afternoon
and kick off another round of modest isentropic lift which
should start to pop up convection on radar between 12PM and 2PM.
Nearly saturated soundings will indicate primarily a heavy
rainfall threat with fairly slow moving thunderstorms. However,
mid level lapse rates and vertical wind shear look to be more
than sufficient to get a few storms to become strong to severe.
While the plentiful moisture points more towards stronger storms
producing ample amounts of small hail, isolated large hail is
still possible along with the usual strong winds. The
environment for strong to severe storms will be most favorable
inside roughly a Laramie to Glendo to Bridgeport triangle.
Isentropic lift will continue all the way through the night and
into Tuesday morning, so some shower and isolated thunder
activity is expected to remain on the radar for most of the
short term forecast period. Some of this nocturnal activity
could still produce heavy rainfall and hail.
Tuesday will have a similar environment to Monday across the area.
Moisture looks even higher, pushing the 97.5 to 99th percentile in
some areas. Dewpoints in the 60s may cover most of the NE panhandle
and even into far eastern Wyoming, while nearly saturated air
remains in the mid to upper levels of the atmosphere. A more potent
shortwave aloft is expected to push through the area and force
another round of scattered to numerous thunderstorms. As a result,
we`ll be looking at another locally heavy rainfall threat. Most
model guidance shows weaker lapse rates Tuesday, which may reduce
the hail threat. However, an increase potential for upscale
organizing compared to Monday may lead to a slightly higher threat
for strong thunderstorm winds.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 209 PM MDT Mon Aug 12 2024
Upper-level troughing will be positioned over northern Idaho with a
strong ridge across the central CONUS on Wednesday. 500mb vorticity
maxima will eject out ahead of the trough, enhancing lift across the
region. Northwesterly flow at 700mb will continue through the day as
a 700mb trough moves off to the east of the region. Surface dewpoints
across western Nebraska will be in the mid-50s to low-60s with
dewpoints closer to the 40 to 50F mark across southeast Wyoming. The
PW values are progged to increase into the 1.1-1.3 inch range across
western Nebraska and closer to an inch across southeast Wyoming.
With upper-level support pushing across the area at this same time,
isolated to widely scattered showers and thunderstorms will be
possible Wednesday afternoon and evening. Forecast NAM and GFS
soundings suggest weak steering flow with minimal shear across
western Nebraska. With PW values well over 1.0 inches, weak steering
flow, and MLCAPE around 1000-1500 J/kg, slow moving, heavy rain
producers are possible Wednesday afternoon. SPC has a Marginal Risk
of severe weather just off to the east on Wednesday. Temperatures
will be warm, but more seasonable for this time of years. Highs will
range from the mid-70s to upper-80s across the Panhandle.
For Thursday, a secondary upper-level low attempts to move into the
region, but a ridge is progged to build over the Intermountain West.
This ridge will push the low further to the north. Despite this,
several 500mb vorticity maxima will eject out ahead of the low and
be absorbed into the building ridge. These maxima should enable
enough synoptic lift to get storms going again for Thursday.
Coverage does not look to be as good on Thursday, due to the less
concentrated synoptic lift over the region and the displacement of
the low to the north. Weak MLCAPE will be present across western
Nebraska, around 500 J/kg. Bulk shear will be weak as well Thursday,
so any showers and thunderstorms that do develop with the
disturbance aloft will likely not be severe and will struggle to
maintain themselves. Highs will be slightly cooler than Wednesday
due a delay in the warmest 700mb temperatures moving overhead. Highs
will be in the mid-70s to low-80s across the region.
The remaining long term forecast will be dominated by a building
upper-level ridge across the western CONUS. The ridge will still be
rather flat on Friday, so precipitation chances remain as a few
disturbances traverse through the ridge. However, Saturday onward,
the ridge will become amplified. Precipitation chances will decrease
significantly for the weekend, but could see some isolated
convection due to daytime heating and terrain-induced lift. Highs
for the weekend will be in the mid-80s to mid-90s with warm
temperatures continuing through the early half of the weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 522 PM MDT Mon Aug 12 2024
Afternoon showers and thunderstorms are ongoing across southeast
Wyoming and western Nebraska. The only terminal currently being
impacting is LAR. Outflow boundaries from the storms over
northern Colorado moved through CYS and flipped the winds to
easterly. Isolated to scattered showers and thunderstorms
continue through the evening hours. Low clouds and fog could
move into SNY and AIA during the early morning hours and
continue into the late-morning hours once again.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
MESOSCALE...BW
SHORT TERM...MN
LONG TERM...AM
AVIATION...AM
Area Forecast Discussion
National Weather Service Gray ME
1039 PM EDT Mon Aug 12 2024
.SYNOPSIS...
Skies clear tonight as low pressure swings northeast. A trough
will swing into the region mid week, bringing additional chances
of showers or thunder. Upper level low pressure resides into
late week, before departing ahead of high pressure. Near normal
temperatures and very little chance of widespread rain this week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
1015 PM Update...
Any leftover showers or sprinkles will continue to dissipate
over the mountains over the next hour or two, leaving all areas
with chilly conditions and varying amounts of clouds. Will
continue with patchy fog in the valleys for the overnight hours.
Otherwise, just minor edits to the near term portion of the
forecast.
Update...
A few showers continue over the region this evening, but the
general trend will be for the precipitation to dry up over time.
The latest HRRR appears to have a good handle on this trend.
Skies will become mainly clear after sunset in some areas. With
light winds and temperatures cooling, this will lead to the
development of patchy fog.
Prev Disc...
Impacts:
* No significant weather impacts expected.
Radar shows scattered showers continuing to stream into the
area at this hour. Showers will continue to traverse the area
through this evening as the trough gradually swings through. An
isolated thunderstorm is not out of the question, especially in
southern zones that saw the most sun today. These rain showers
will generally be light, however with modest PWATs and low level
lapse rates any stronger showers or isolated thunderstorms
would be capable of moderate rain rates and gusty winds. Severe
weather is not expected. Skies gradually clear overnight as the
trough departs, maybe a couple degrees warmer with the increased
cloud cover, so kept low temperatures very similar to last
night with low 50s in the mountains and foothills, and mid- to
upper 50s to the south.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
Impacts:
* No significant weather impacts expected.
Tomorrow looks to be warmer as return flow behind the departing
low pressure ushers in some 12C 850 mb temperatures. Mostly
clear skies and good mixing should allow temperatures to climb
into the low to mid-80s south of the mountains, with mid-upper
70s to the north. Northerly flow will keep most of the area dry,
but can`t totally rule out a diurnally driven shower in the
mountains or along the seabreeze boundary during the afternoon.
Skies remain clear for Sunday night, so expect yet another night
with temperatures in the low 50s in northern zones, and mid- to
upper 50s in the south.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Overview: Daily chances for afternoon showers this week, some
thunder mixed in. Thunder chances will be greater Wed/Thurs
afternoon as a boundary drops out of Quebec. Surface high
pressure moves in late week. Low pressure then advances into the
Great Lakes this weekend, with rain chances increasing late.
Details: Wednesday, an embedded shortwave in broader low
pressure will swing down from Quebec/New Brunswick. This may
create a similar environment we saw on Monday as cooler air
aloft moves in. Expect a chance of showers and thunderstorms in
the afternoon as heating peaks. Shear is very low in this
environment, and think daytime instability will be imbalanced.
Thus stronger cells may lack sustainable updrafts and rain
themselves out. This could still result in gusty winds as rain
cooled air descends, but otherwise signs point to sub severe
storms at this time.
Wednesday night, this trough organizes into an upper low,
remaining overhead Thursday. Elevated instability remains, and
a few persistent overnight showers are be possible. The
placement of the low could bring similar conditions for
Wednesday in terms of shower/thunder potential.
High pressure moves into the Northeast Friday and early this
weekend. This will bring lower chances of daytime showers, but
the next weather maker will be moving into the Great Lakes for
additional rain chances late this weekend.
Overall, daytime and overnight temps ride within a few degrees
of normal, perhaps cooler if cloud cover prevails during the
day.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR will continue to prevail tonight, with the
possibility of some localized IFR/LIFR with fog at LEB and HIE
especially since they will see showers this evening.VFR
conditions will then return through Tuesday night. Isolated
thunder is possible with passing showers this evening.
Westerly/northwesterly winds are expected to remain light.
Long Term...SHRA Wednesday and Thursday. This could prompt
occasional MVFR ceilings at times. Fog may develop Wed night,
bringing some visibility restrictions across the interior.
Little notable winds.
&&
.MARINE...
Short Term...Conditions will remain below SCA criteria through
Wednesday night. Winds will be generally westerly/northwesterly
with a seabreeze Tuesday afternoon. Gusts will generally be
10-15 kts.
Long Term...Below SCA conditions with waves 1 to 2 ft. Broad
upper level low pressure forms Wed/Thurs over New England. This
will bring some showers to the waters, but little notable wind
speeds.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
Cannon/Baron
Area Forecast Discussion
National Weather Service Wilmington NC
820 PM EDT Mon Aug 12 2024
.SYNOPSIS...
A front stalled nearby will maintain unsettled weather through
tonight before a gradual drying trend begins as the front pushes
to the south. Building high pressure with cooler, drier air
should lead to rain-free week before it shifts offshore this
weekend.
&&
.UPDATE...
As of 820 PM...The bulk of the heavy showers/tstms is moving at
a good clip away from the Cape Fear region. Plan to lower the
Flood Watch with the next update. There could be a few
showers/isolated tstms overnight but chances will decrease. No
major changes planned.
&&
.NEAR TERM /THROUGH TUESDAY/...
Frontal boundary has sagged 2/3 the way across the CWA from the
NW. There is good convergence between the font and the sea
breeze in Brunswick County and some CAMs like the HRRR show what
will be a considerable flooding threat in our current FFW.
Convection will still grow rather widespread along and south of
the boundary heading into the evening. Soon thereafter coverage
will drop quickly from NW to SE as the front moves south , but
some low chance POPs will linger along the immediate coast. WNW
flow aloft continues into Tuesday. This keeps the push on the
front rather weak, PW values only dropping from 2.4 to 2.0".
This lingering moisture paired with the embedded vorticity
maxima will still call for low end chance POPs but some
increased dry air aloft should really start to limit the chance
for heavy rainfall.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Troughing over the northeastern US will begin to push a
previously stalled cold front offshore on Tuesday as surface
high pressure works its way into the region overnight. A slow
propagation of high pressure could maintain a slight chance of
showers along the coast on Wednesday, but models are gradually
decreasing this chance over the last several days, and punch of
the upper trough should allow this trend to continue. Any
showers that develop in this environment should be shallow and
brief.
Temperatures should remain slightly below normal with lower
humidity. This will undoubtedly be a welcome change. Daytime
highs in the mid and upper 80s with lows in the upper 60s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Subsidence following the trough and surface high pressure will
maintain dry conditions on Thursday. Temperatures will remain
slightly cooler than normal, mid to upper 80s expected. These
conditions are expected to continue through Friday and possibly
into Saturday although confidence is low for the upcoming
weekend.
Models continue to hint at another approaching trough and
associated cold front next weekend. Deep southwest flow ahead of
the trough will lead to increasing moisture while the boundary
should allow for a better chance of showers and storms for
Saturday and Sunday. Decreasing moisture aloft on Sunday should
decrease coverage, but the latest forecast maintains a slight
chance of storms even into early the following week.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Convection has cleared the KILM area, and will at KCRE/KMYR by
01Z, while VCSH/VCTS at KFLO through 02Z. Otherwise, IFR CIGs
and mainly MVFR VSBYs are possible during the overnight, until
12-13Z time-frame. VCSH/VCTS again during Tuesday, though
coverage shouldn`t be as significant as it has been the past few
days.
Extended Outlook... Predominantly VFR expected this week
outside of morning fog and aftn/evening convection through
Wednesday, as we return to a more typical summertime pattern. A
period of dry weather begins by Thursday.
&&
.MARINE...
Through Tuesday... The current southwesterly winds will start
to veer tonight as cold front pushes through, eventually turning
all the way to NE. Winds will remain very light through the
veer so wave faces shouldn`t steepen significantly. The 5 second
wind chop will coexist with swells at both 8 and 10 seconds.
Tuesday Night through Saturday Night... Cold front will drift
south of the area on Tuesday introducing northerly winds across
the region. Winds gradually veer to the east through the middle
of this week before high pressure pushes offshore this weekend.
High pressure departs this weekend and an approaching cold front
will re- establish southerly flow across the region. Swells
from Potential Tropical Cyclone Five (forecast to become
Ernesto) will arrive on Friday. SE swells will build through the
weekend as shorter period, but higher amplitude waves arrive.
&&
.TIDES/COASTAL FLOODING...
Other - Rip Currents: Swells from Potential Tropical Cyclone
Five will arrive late Friday or Saturday and continue into this
weekend. While the timing of local surf impacts is not certain
at this time, we do expect dangerous surf and strong rip
currents to exist at some point this weekend.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
NC...None.
SC...None.
MARINE...None.
&&
$$
SYNOPSIS...ILM
UPDATE...SRP
NEAR TERM...MBB
SHORT TERM...21
LONG TERM...21
AVIATION...MBB
MARINE...MBB/21
TIDES/COASTAL FLOODING...ILM
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1012 PM EDT Mon Aug 12 2024
.KEY MESSAGES...
- Below normal temperatures and dry weather will persist through
mid week.
- Humidity and the possibility of showers and thunderstorms will
climb late in the week.
&&
.UPDATE...
Issued at 1012 PM EDT MON AUG 12 2024
Showers or sprinkles continue to move across portions of IL and IN
as well as western and into central KY ahead of an approaching
disturbance. Mainly high clouds have increased ahead of this
across eastern KY, with some mid clouds also present. Some
convective allowing models including the HRRR have been a bit more
robust in coverage of this activity compared to the previous
forecast. With this in mind, a couple hours of slight chance pops
were included for much of the north for these, with the areal
extent of sprinkle chances expanded a bit further south. Overall,
the probability of measurable precipitation from this is low.
UPDATE Issued at 754 PM EDT MON AUG 12 2024
Hourly grids were freshened up for the next couple of hours based
on recent observations and trends. This led to no substantial
changes at this point.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 429 PM EDT MON AUG 12 2024
The latest upper level map features troughing positioned from
eastern Canada through the eastern Great Lakes and New England.
Ridging is currently centered over Texas, with west northwest flow
aligned from the Midwest through the Ohio and Tennessee valleys.
At the surface, high pressure is sprawled from the northern Plains
through the central and southern Appalachians. A cool start,
combined with some passing thicker high level clouds kept most highs
near, or just on either side of the 80 degree mark.
The models are in very good agreement through the short term. An
embedded short wave trough will traverse the Ohio Valley late
tonight into early Tuesday morning, bringing increasing and
somewhat lowering clouds to most of the Commonwealth. Some of the
model guidance is also showing some light precipitation; however,
given the drier low levels in place and the lack of surface
features, will only be including a period of sprinkles overnight.
The combination of a mostly clear beginning to the night as well
as dew points starting out in the low to mid 50s, should allow
temperatures in the cooler valleys to dip into the mid 50s, while
broader valleys and ridges cool off to the upper 50s to lower
60s. The short wave will exit Tuesday morning, with 500 mb
heights recovering during the day, and mostly sunny skies
prevailing. Temperatures have been running a bit on the cooler-
side of the guidance with this air mass, so have stayed closer to
the 25th percentile of the NBM, with highs in the lower 80s at
most sites. Mostly clear skies and continued lower humidity will
allow for similar lows Tuesday night compared to tonight, despite
the warmer start.
.LONG TERM...(Wednesday through Monday)
Issued at 405 PM EDT MON AUG 12 2024
The period will begin with mid-level heights building across parts
of the Middle and Upper Mississippi River Valleys and trough in the
east toward much of the Ohio Valley. At the surface, we will see
high pressure centered across the Upper Ohio Valley and Great Lakes
regions. This will lead to weak northerly flow at the surface. This
will keep it dry and near normal through at least most of the day
Thursday. The mid-level heights do tend to rise based on most of the
ensemble and deterministic solutions as a ridge attempts to build east.
This will lead to a little warmer weather Thursday, with
afternoon highs in the upper 80s. The mornings will see river
valley fog and temperature splits, with valley locations in the
mid to upper 50s both mornings.
An upper level wave will push into the Upper Mississippi River Valley
by early Friday and quickly deepens a low that tracks into the Great
Lakes. This will all help to send a warm front toward the Ohio Valley
Friday and help to increase the chance of rain to around 50-60
percent on Friday. This overall troughiness sticks around through
the reminder of the period chances of rain into the 40-60 percent
chance range from time to time through Sunday. There are some
differences in the overall evolution of this system in the ensembles
and deterministic solutions that complicate the overall chances
of rain. Particularly with how quickly it moves the cold front
east through this weekend. Therefore stuck close the NBM for now
to handle these differences and trends overtime. Right now, when
looking at the ensembles the greatest chance (around 30 percent)
of seeing over a half an inch in a 24 hour period will be Friday
into Saturday night and this seem reasonable based on the overall
trends in the other guidance, better forcing signals, and
increasing moisture, with PWATs closer to 1.75 inches. Given the
increasing cloud cover and chance of rain through the weekend
afternoon highs will be running a bit cooler in the low to mid
80s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 759 PM EDT MON AUG 12 2024
VFR conditions were observed at issuance time and are expected to
prevail through the period. Any fog formation will be limited to
deeper river valleys between 06 and 13Z, with some reductions to
MVFR possible if that materializes. An increase and lowering of
mid and high level clouds is still anticipated during the first 6
hours of the period in response to an upper level disturbance
passing across the Ohio Valley. Some sprinkles could fall from
these between about 03Z and 12Z. Winds are still expected to
average around 5 KT or less, generally between north and
northeast.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...GEOGERIAN
LONG TERM...DJ
AVIATION...JP
Area Forecast Discussion
National Weather Service North Platte NE
646 PM CDT Mon Aug 12 2024
.KEY MESSAGES...
- Abundant moisture may cause thunderstorms capable of locally
heavy rainfall tonight and again Tuesday.
- Isolated severe storms are possible Tuesday and Wednesday. The
primary hazards are large hail and wind damage.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 347 PM CDT Mon Aug 12 2024
A fairly strong UA disturbance moving through ern WY this
afternoon is the basis for chance to likely POPS across wrn
Nebraska tonight. Satellite shows a second disturbance across
nrn UT this afternoon and the RAP model shows both disturbances
sweeping through wrn and scntl Nebraska tonight.
The forecast uses a full blend of models, some of which, like the
GFS, show a "wet foot" across wrn Nebraska while others, like the
NAM show little or no rainfall. The reason for this is a second area
of organized thunderstorms will likely form across the Palmer divide
where the dynamics are weaker but the focus is better. Some models
suggest only one area of significant rainfall will occur- across
Colo. It worth noting satellite shows an separate UA disturbance
across wrn Colo which will move east and intercept the ongoing
convection across ern Colo/KS late tonight.
The drier model solutions across Nebraska tonight are wetter across
KS and Colo. The forecast wagers the strong dynamics across WY, UT
and Colo will support significant rain chances across Nebraska
and Colo/KS.
Thunderstorm chances are in place again Tuesday evening and
overnight for dynamics lifting east-northeast through Colo and
Nebraska. Water vapor and the models indicate a TUTT or
tropical upper tropospheric trof across AZ plus a disturbance
off the coast of nrn CA moving east-northeast. The models will
phase these disturbances across Colo/WY Tuesday presenting very
favorable upper level support.
The main upper low is far north across MT and this should be strong
enough to drive a warm front through wrn/ncntl Nebraska after
sunrise Wednesday morning. For the system Tuesday, we have focus,
moisture and upper level support. Chance/likely POPs for this event
follow the dynamics favoring swrn and ncntl Nebraska.
For both events, the models are in good agreement ramping up PWAT to
1.50 inches or higher and BUFkit indicates significant warm
precipitation processes to around 11kft.
Severe weather risks are marginal both days and this is mainly
forced by strong 0-6km shear 25-40 kts. The 0-8km is much stronger,
40-60 kts and given the modest instability, MLCAPE 2000-3000j/kg,
isolated severe storms would be the most likely concern. Out of all
the forecast features now through Wednesday morning, severe weather
is the most uncertain. The reason for this is the lack of sfc focus
and low level warm air advection which is anchored well south across
KS, south of a sfc cold front.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 347 PM CDT Mon Aug 12 2024
The upper level ridge of subtropical high pressure centered over
north Texas will drift east into LA this week and then migrate
west and amplify across NM this weekend and beyond. Nebraska
will likely remain under the belt of strong westerlies, or
northwesterly winds surrounding the ridge. More important is
subtropical moisture appears to be rotating around the ridge,
moving through Nebraska on many days. This would support at
least an isolated thunderstorm chance and a scattered chance if
a disturbance was present.
Temperatures at h700mb will warm to around 15C Saturday and remain
there through Monday. The reason for this is the upper level ridge
will amplify north into the cntl Rockies but it`s worth noting
mixing heights may not reach 700mb, especially if a backdoor cold
front moves into Nebraska as shown by the models. The temperature
forecast is relatively modest featuring highs in the 80s to near 90
next weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 628 PM CDT Mon Aug 12 2024
VFR conditions will continue through approximately 06Z Tuesday
before a stratus deck builds in across much of southwest and
north central Nebraska. IFR/LIFR CIGs are anticipated to impact
KLBF from 11 to 17Z Tuesday before scattering out through the
afternoon. Bulk of the stratus appears to remain to the south of
KVTN with MVFR CIGs expected. Along with the stratus, fog is
expected to develop again overnight, which could cause
visibilities to drop to 4SM or lower.
Some scattered showers and embedded thunderstorms remain
possible across the area tonight. However, confidence is too low
to include with this TAF issuance. Will monitor closely with
subsequent TAFs.
Southeasterly winds continue at generally 10kts or less through
the bulk of the period. For VTN and northern terminals, winds
become breezy gusting up to 25kts Tuesday afternoon and evening.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Viken
Area Forecast Discussion
National Weather Service Reno NV
248 PM PDT Mon Aug 12 2024
.SYNOPSIS...
* Critical fire weather conditions continue today through this
evening along with choppy lake conditions due to a passing cold
front.
* Smoke from ongoing wildfires is expected to impact the portions
of the area today particularly the Reno/North Valleys Area with
smoke from the recent Gold Ranch Fire.
* Low pressure will persist this week and into the upcoming weekend.
This will result in noticeably cooler weather by August standards.
It will remain mostly dry with typical daytime breezes.
.DISCUSSION...
Upon looking at the latest RAP analysis of the upper air pattern,
the CWA has a southwesterly flow aloft being underneath the eastern
portion of an upper air trough over the Pacific Coast. Current
surface observations along with satellite imagery report dry
conditions across the CWA and breezy winds from the west and
southwest with some scattered clouds over portions of the area.
along and east of the CA/NV border. Forecast guidance shows the
upper air trough moving eastward through the rest of today with the
base of the trough reaching over CWA on Tuesday allowing for a more
zonal flow aloft by midday. With this pattern aloft, a cold front
remains on track to pass through the region this evening. As a
result of this approaching cold front, the dry conditions are
expected to continue with minimum afternoon RH values ranging
between the upper single digits and the middle teens through a
good portion of the CWA. Guidance also shows widespread
southwesterly to westerly winds gusting up to 35 mph with some
places possibly nearing 40 mph mark. Due to these conditions, the
current Red Flag Warning continues and was expanded this morning to
include the Lake Tahoe Area (See the Fire Weather Section for
more details). A Lake Wind Advisory continues through this evening
as well with these winds allowing for choppy waves in lakes
within the region (See the Lake Wind Advisory product for more
information). Blowing dust may also be possible this afternoon in
desert areas of western NV which could reduce visibilities, so
please use caution if traveling through places where this occurs.
There is a slight chance (~15%) for a brief isolated shower in
some portions of western NV this evening that will not yield much
if any measurable precipitation though low confidence for this to
occur.
While smoke is not currently being seen in the observations, some
sites particularly those near RNO reported it this morning due to
the recent start of the Gold Ranch Fire near the CA/NV border. The
latest HRRR near surface smoke forecast shows smoke increasing a bit
in intensity from the source and blowing west along I-80 into
portions of Reno/Sparks and the North Valleys during the late
afternoon/evening hours. However, the model does have the smoke
coverage and intensity diminishing by the late evening hours. As
this may continue to affect air quality, please visit
fire.airnow.gov for the latest air quality information in your
area. The HRRR model shows the same pattern with late
afternoon/evening smoke once again on Tuesday impacting the Reno
area with the wildfire continuing to burn. We will be monitoring
this situation and updating the forecast as needed, but not
anticipating any severe impacts to visibility. The HRRR also
forecasts smoke from the Park Fire entering western Lassen County
as well smoke from the Middle Fire entering Mono and Mineral
Counties though the intensity from these do not appear to be that
great at this time.
After tonight`s cold front passage, breezy afternoon winds gusting
up to around 20-25 mph can be expected for the region with slightly
increased minimum relative humidity values that will allow for a
lesser fire weather concern though potentially elevated in the CWA.
On Wednesday, models show an upper air low moving towards the OR
coast by the evening which may allow for some slight precipitation
chances (15-20%) for northern portions of the CWA near the OR
border. Guidance shows this low passing by the northern part of the
CWA on Thursday before another larger trough moves onto the Pacific
Coast behind it on Friday. With this setup in the forecast, cooler
temperatures compared to those earlier in the month are expected
through the week along with the typical afternoon breezes. However,
models hint at winds to increase slightly towards the end of the
week with the aforementioned trough approaching, so will be
monitoring that though not anticipating severe impacts at this
time. -078
.AVIATION...
VFR conditions are expected for the REV terminals today going into
tomorrow with gusts this afternoon ahead of a cold front up to
around 25-30 kts lasting until around 02Z-03Z when winds begin to
decrease. The desert portions of western NV might see some localized
blowing dust during this afternoon, but not anticipating it reducing
visibilities at REV TAF sites. There may be some haze/smoke based on
the latest HRRR particularly around KRNO this evening due to the
nearby Gold Ranch Fire, but not anticipating it to affect the flight
restrictions at this time. While overnight winds look to generally
be light, southern portions of the CWA such as KMMH may see some
periods of LLWS beginning around 05Z. -078
&&
.FIRE WEATHER...
* Red Flag Warnings remain in effect until 8PM for very dry
conditions and wind gusts to 30-35 mph. A quick snap-shot of area
observations show areas where the humidity ranges from the low to
mid teens across many areas of the Sierra Front with RH`s this
afternoon dropping into the single digits across parts of the
Basin and Range. Wind gusts have increased to 30-35 mph through
many known wind prone areas across the Sierra Front and along
Sierra foothills as well.
* Winds/mixing will start to wind down after this evening with RH
recoveries increasing as a cooler air mass filters near to a few
degrees below average temperatures across northeast CA into
western Nevada through Tuesday. Elevated fire conditions could
persist the remainder of the week through the weekend due to
continued dry conditions, coupled with the typical afternoon/
evening west-southwest winds gusting to 25-30 mph. -Amanda
&&
.REV Watches/Warnings/Advisories...
NV...Red Flag Warning until 8 PM PDT this evening
NVZ420-421-423-429-458.
Lake Wind Advisory until 9 PM PDT this evening NVZ002>004.
CA...Red Flag Warning until 8 PM PDT this evening CAZ272-278.
Lake Wind Advisory until 9 PM PDT this evening CAZ072-073.
&&
$$