Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/31/24
Area Forecast Discussion
National Weather Service Amarillo TX
642 PM CDT Fri Aug 30 2024
...New AVIATION...
.SHORT TERM...
(This evening through Saturday night)
Issued at 151 PM CDT Fri Aug 30 2024
Widespread clouds are present generally south of the Canadian River
with intermittent cloud breaks being observed. Meanwhile, dry air
aloft is being advected in from the north which has caused clouds to
erode north of the Canadian River with the exception of cirrus from
convective debris. Rain is ongoing in the southeastern Texas
Panhandle with some isolated to scattered showers in the
southwestern Texas Panhandle. Some sort of weak impulse can be
observed faintly on water vapor satellite and is faintly visible on
radar as a counter-clockwise swirl... though it had been more
apparent in the late morning hours. Have adjusted the highs today
from the NBM to increase temperatures north of the Canadian River
where clouds have broken up while cooling temperatures a few degrees
south of the Canadian River where clouds are more prevalent.
Forecast models indicate additional dry air aloft will dig further
south into the Panhandles later this afternoon and tonight which, in
addition to the lack of mentionable forcing mechanism, should cause
rain chances to dissipate from north to south. Have left 20-30% PoPs
in the southern Texas Panhandle later this afternoon as there is a
slight chance for re-development of showers with the previously
mentioned impulse. HRRR suggests there will be some thunderstorms in
the southwest Texas Panhandle in association with that impulse, but
have a hard time believing it given that highs are expected to only
reach into the 70s. Otherwise, have cut PoPs down from the NBM
tonight to reflect this dry air intrusion, but have left some PoPs
in for the southern Texas Panhandle throughout tonight.
Expecting the clouds to mostly clear out Saturday with very low to
no chance for rain, though can`t entirely rule it out in the far
southern or far southeastern Texas Panhandle.
Vanden Bosch
&&
.LONG TERM ...
(Sunday through next Thursday)
Issued at 151 PM CDT Fri Aug 30 2024
Most medium/longrange deterministic members continue to showcase
dry conditions for Sunday, owed to northeasterly sfc flow and
ridging downstream of approaching shortwave trough. On Monday,
the GFS and ECMWF both depict this shortwave trough to become
increasingly negatively tilted with its right-exit region
positioned favorably for large-scale forcing for ascent. However,
despite an optimal synoptic configuration, rainfall chances appear
rather uncertain on Monday and Tuesday (POP`s of 15-23%) given
model disparity of sfc pattern, moisture return, and cloud cover.
For instance, the GFS suggests weakening and a eastward shift to
the Eastern CONUS sfc high, allowing ample BL moisture return to
CWA. The Euro however maintains the strength and position of the
high, inducing east/northeasterly winds, sweeping highest
moisture/PWATS south of CWA. Following Tuesday, a mid-level ridge
is expected to build over the Great Basin in conjunction with a
quasi-zonal 250mb pattern. Thus, rain chances appear slim but are
not non- existent, especially with modest moisture return, well-
timed with a embedded shortwave. Great Lakes troughing may throw
a wrench in the forecast though, forcing westward shift of ridge
and yielding northerly CAA. POPs in the lower teens have therefore
been introduced, mostly for the southeastern CWA on Wednesday and
Thursday of next week.
Temperatures are expected to peak into 80`s and lower 90`s on
Sunday, followed by a slight reduction into the upper 70`s and
80`s for Monday and Tuesday. The NBM suggests temperatures rebound
back into the 80`s and even lower 90`s for Wednesday and Thursday
of next week. Nonetheless, possible rain, cloud cover, and
placement of ridge/trough inspires much uncertainty in the high
temperature forecast.
Landry Judd/Vanden Bosch
&&
.AVIATION...
(00Z TAFS)
Issued at 638 PM CDT Fri Aug 30 2024
For the 00Z TAFs, VFR conditions are expected to prevail at KGUY,
KDHT, and KAMA through late Saturday afternoon.
02
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 61 85 57 86 / 10 10 10 10
Beaver OK 57 85 53 88 / 0 0 0 0
Boise City OK 54 83 51 84 / 0 0 0 0
Borger TX 61 88 57 91 / 10 0 0 10
Boys Ranch TX 59 86 57 87 / 10 0 0 10
Canyon TX 60 84 55 85 / 20 10 10 10
Clarendon TX 62 85 60 88 / 30 10 10 20
Dalhart TX 55 83 52 84 / 10 0 0 10
Guymon OK 55 84 51 86 / 0 0 0 0
Hereford TX 59 85 55 86 / 20 10 10 10
Lipscomb TX 61 85 57 90 / 10 0 0 10
Pampa TX 60 84 57 87 / 10 0 0 10
Shamrock TX 63 85 59 89 / 20 10 10 10
Wellington TX 64 88 62 91 / 30 20 10 20
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...None.
OK...None.
&&
$$
SHORT TERM...52
LONG TERM....52
AVIATION...02
Area Forecast Discussion
National Weather Service State College PA
1115 PM EDT Fri Aug 30 2024
.SYNOPSIS...
* Severe thunderstorms capable of producing damaging wind gusts
and flash flooding are possible Saturday afternoon into the
evening
* Extended stretch of seasonably cooler, fall-like weather for
the start of September
&&
.NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...
A moist southeast flow off of the Atlantic will maintain the
stratus deck across nearly the entire forecast area overnight.
Model soundings indicate the cloud layer will be too shallow to
support drizzle over all but perhaps Sullivan/Schuylkill
Counties. However, ridge top fog looks like a good bet.
A band of showers/tsra over Southern Ontario associated with an
upstream shortwave will approach the N Mtns late tonight.
Latest convection-allowing model guidance indicates the best
chance will remain north of the state, so we`re carrying only
slight chance POPs across the northern counties.
There`s not much room for cooling tonight with dewpoint
depressions already low and overcast skies. Expect readings at
dawn to be in the mid 60s over much of the forecast area.
&&
.SHORT TERM /7 AM SATURDAY MORNING THROUGH MONDAY/...
The stalled front over Western PA is progged to return as a warm
front Saturday in response to an upper trough approaching from
the Grt Lks. Low level RH fields indicate a gradual west to east
erosion of the low clouds during the late morning and
afternoon. Falling heights and surging low level moisture,
combined diurnal heating, results in fcst CAPE rising >1000 J/kg
over most of region during the afternoon. Convection-allowing
models all indicate discrete tstorm development around midday
over the Allegheny Plateau, with fairly rapid upscale linear
growth ahead of a weakening cold front, which shifts east into
the Susq Valley toward early evening.
Modestly strong mid level flow supports some risk of severe
weather across all of Central PA. However, the most favorable
environment based on latest guidance is across the Central Mtns,
where enhanced low level backing flow in the vicinity of the
advancing warm front results in a region of enhanced updraft
helicity in the the 12Z HREF. Values >150 m2/s2 in this area
support potential supercell development and associated large
hail/damaging wind risks.
Will also have to contend with the potential of localized flash
flooding Sat afternoon/evening. HREF guidance indicates the
possibility of localized 3+ inches over the Central Mtns, where
FFG remains relatively low from recent rain. The potential of
flash flooding looks lower east of the Main Stem Susquehanna
River, where FFG is higher.
A lead shortwave and weak cold front should push across the
region Sat night, causing showers/tsra to diminish. However,
will maintain a chance of showers through early afternoon
Sunday in the vicinity of the dying front over Southern PA. Much
drier air is progged to spread south into the region from north
to south Sunday, resulting in mostly sunny skies over much of
the region and clearing skies in the south by late afternoon. A
secondary cold front will approach the NW Mtns by Sunday
evening, perhaps accompanied by a late day shower over that part
of the state.
A large high pressure system is forecast by all guidance to
build southeast into PA Sunday night into Monday, accompanied by
fair and cool weather, along with much lower humidity.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
All medium range guidance supports fair and cool weather Tuesday
and Wednesday, as high pressure pressure builds over PA. Calm
wind and clear skies under the high should result in efficient
radiational cooling and min temps a bit below NBM guidance,
along with AM valley fog in the deep river/stream valleys of the
Alleghenies. Moderating temps are expected the second half of
the week, as the high slips off of the East Coast and a return
southerly flow develops. A cold front will push into the
region late Friday or Saturday, accompanied by our next chance
of showers or tstorms.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Prevailing VFR conditions observed across the western sites
(BFD/JST/AOO) with MVFR restrictions based on a low-level cloud
deck (~1-2kft AGL) across the eastern airspace as of 00Z
Saturday. In general, expect these trends to continue over the
next couple of ours with moderate (50-60%) confidence with the
biggest uncertainty at BFD where some SHRA could make way into
the airfield mainly between 0100-0130Z. This could bring about
slightly lower ceilings (MVFR) although some erosion of the low
cloud deck has been noted on Nighttime Microphysics.
After chances of SHRA dwindle at BFD (~02-03Z Saturday), expect
conditions to deteriorate at a majority of central PA airfields
overnight, with MVFR (BFD/JST) to LIFR (AOO/UNV/IPT) conditions
possible. At this time, the highest confidence (60-70%) will be
at AOO, with slightly lower confidence at UNV/IPT given a
combination of 12Z HREF guidance (> 70%) of IFR/LIFR ceilings,
GLAMP guidance and RAP model soundings outlining moisture in the
lower-levels. At this time, thoughts are that visibility
restrictions will be minimal (4-6SM) with lower ceilings being
the main basis for restrictions. Further west at BFD/JST, lower
confidence (20-30%) in any restrictions below MVFR at this time.
For airfields in the LSQ (MDT/LNS), HREF outlines some higher
probabilities in IFR/LIFR conditions and have outlined these in
the 04-14Z timeframe despite GLAMP guidance not being the most
robust on ceilings below 1kft forming, thus moderate (40-50%)
confidence in these restrictions.
Gradual improvement is progged by the bulk of model guidance
after sunrise, although there is some discrepancies on timing
and magnitude of improvement. Given some uncertainty, moderate
confidence in the 13-18Z timeframe although expect most
airfields to resolve towards high-end MVFR to low-end MVFR
around 16Z Saturday. SHRA/TSRA is expected across much of the
airspace during the afternoon and evening hours and have given a
first attempt at SHRA onset timing continuing through the end
of the 00Z TAF period with TSRA mentions limited to BFD/JST/AOO
where there is slightly higher confidence.
Outlook...
Sun...AM Fog W. Lingering showers, drier air moving in PM.
Mon-Wed...VFR w/ no sig wx expected.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Steinbugl/Banghoff
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...Fitzgerald
AVIATION...NPB
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
557 PM CDT Fri Aug 30 2024
.KEY MESSAGES...
- Showers and storms possible for southeastern portions of the
region this evening.
- Cooler temperatures expected this weekend and beyond.
&&
.DISCUSSION...
Issued at 214 PM CDT Fri Aug 30 2024
Scattered showers traversing the forecast area are expected to
come to an end this evening. Chances for scattered showers and
storms remain in the far southeastern portions of our region as
instability associated with a cold front continues to progress
east. The atmosphere is predicted to be modestly buoyant this
evening, with surface- based CAPE values anywhere from 300-1300
J/Kg in southern portions of the area. Furthermore, convection
allowing models (CAMs) show possible storm coverage in Cooper
and Howard counties in the evening hours, with the threat for
severe weather fortunately being low. Additionally, the HRRR
shows some scattered activity in southern portions as well,
though the storm environment remains relatively meager. If
stronger storms do occur, the main threats will primarily be
gusty winds and possibly small hail.
Otherwise, mostly clear to partly cloudy conditions will prevail
across our area through the evening and overnight hours. Tonight`s
lows are expected to be at or slightly below-normal as a cooler,
continental air mass behind the upper-level low settles into the
forecast area and shifts the surface wind flow in a northerly
manner. Lack of cloud coverage also allows for substantial
radiational cooling, which aids in keeping temperatures feeling
almost fall-like. Temperatures appear to bottom out in a northeast-
to-southwest gradient, with northern portions of the area in the
upper 50s and places to the south experiencing lows in the lower to
mid 60s tonight.
Quieter weather is forecast for the weekend as 925MB surface
analysis reveals a high pressure moving into south-central Iowa
overnight. Meaningful relief from the heat is in store as seasonable
temperatures return to our region. Highs are expected to range from
the upper 70s to the lower 80s across the forecast area Saturday.
Latest GFS model guidance indicates a more robust surface high
traversing across the central plains, establishing itself as the
main influence of our area`s synoptic weather pattern beginning next
week. As a result, pleasant conditions are expected for Sunday as
well, with places north of I-70 experiencing afternoon highs in the
mid to upper 70s and places south of I-70 peaking in the mid to
upper 80s. Benign conditions to grace the majority of the workweek
as below-normal temperatures are anticipated for the region through
the whole of the forecast period.
Chances for showers and storms may return on Thursday night into
Friday as a cold front associated with broader troughing in central
Canada possibly brings instability across the forecast area. There
is uncertainty in the timing this far out, and the chances for
severe weather remain unknown at this time.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 557 PM CDT Fri Aug 30 2024
VFR conditions are expected for majority of the TAF period. There is
a potential for some MVFR/IFR ceilings early tomorrow morning, but
there is uncertainty in coverage and timing. Winds are anticipated
to stay weak and out of the north for the duration of the forecast
period.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.
&&
$$
DISCUSSION...Hayes
AVIATION...Collier
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
521 PM MDT Fri Aug 30 2024
...New AVIATION...
.SYNOPSIS...
Issued at 200 PM MDT Fri Aug 30 2024
Scattered storms can be expected the next couple of days with
temperatures remaining fairly warm. For Sunday into Monday, clouds
and precip will become more focused over far west Texas and along
the International border into New Mexico. High temperatures will
be below average for these days with some areas over the east not
getting above 80 degrees. Drier air starts to move back in for the
middle of next week with temperatures returning back to around 90
for the lowlands.
&&
.DISCUSSION...
Issued at 200 PM MDT Fri Aug 30 2024
Currently an upper high sits around the Great Basin while to the
SE, the Borderland is on the southwest end of an elongated trough
extending up into northern Manitoba. This trough will be the
weather player through the weekend, the question is to what
extent.
Tonight looks to be the most active as far as potential for strong
storms with heavy rain potential. Storms will be moving slowly and
there is modest shear around of around 25KTS which will allow for
storms to drop locally heavy rain and possibly be sustained for
some time. The strongest storms will move more quickly to the
south. HRRR has backed off on coverage over the eastern half of
the area and focusing more from the RGV to Deming. Other CAMs are
more equal opportunity. With a weak surface boundary around and
the upper trough combining with storm outflows, think scattered
coverage for much of the area looks most likely.
Going into the weekend, models showing agreement that Saturday
will be a down day, likely due to coverage of storms later today
even though we continue to have the upper trough lingering around
the International Border. Should still see storms develop over
area mountains with easterly low level flow continuing and even
areas across the south with the trough could see isolated to
scattered storms. High temperatures will be a little cooler than
today with mid to upper 80s common over the lowlands. Sunday has
some of the biggest discrepancies between models. Seeing a trend
toward a weak low developing somewhere in northern Mexico. EC has
remained consistent being further south, but NAM and especially
the GFS are further north and bring fairly widespread precip to
the southern half of the area. Looking at GFS ensembles, the
operational seems to be on the wettest/coolest side. There will be
a fair amount of cloud cover, at least south which will keep
temperatures below normal. MAV guidance is going 72 for a high
temp while the MET is 78 and NBM 84 at ELP. General trend is down,
but looking at records for this time of the year, 72 would be near
a record low high. Thinking around 80 looks reasonable for ELP,
but out towards Dell City, it may struggle to reach much above the
lower 70s with a better chance for all day cloud cover and rain.
The upper low lingers into Monday before dissipating as upper high
builds into the NM/AZ border region. Precip Monday should then be
mainly far southeastern areas ahead of trough/low with drier air
moving in from the NW. Even the EC is showing nice area of precip
Sun night into Mon for far west Texas into extreme southern NM
which is not common in the summer with the EC, so this leads me to
have a higher confidence there will be some showers overnight
compared to most nights. Temperatures will remain below normal
with highs similar to Sunday.
Upper high starts to really get reestablished by Tue/Wed which
will keep much of the area dry, only area that may see some precip
would continue to be far east. Temperatures will be warming back
up toward normal which is mid 80s to around 90 for the lowlands.
Another upper trough of which we are on the far SW side of will
move in Fri/Sat and bring an increased chance for showers out
east and some slightly cooler temperatures.
&&
.AVIATION...
(00Z TAFS)
Issued at 501 PM MDT Fri Aug 30 2024
VRF conditions expected to persist through the forecast period. Showers
and thunderstorm activity is expected to become isolated around
the 03z to 04z time frame. Put in VCSH as any one TAF site may see
a brief shower before 04z. SCT060 to SCT100 to SCT250 to BKN250
expected to persist through the remaining evening hours, then
becoming SCT100 to SCT250 the rest of the period. Winds expected
to be N to E at 5-15 mph.
&&
.FIRE WEATHER...
Issued at 200 PM MDT Fri Aug 30 2024
A period of cooler and wetter weather, especially south and east,
is in store for the weekend. Temperatures on Sunday into Monday
may not get above the lower to mid 80s anywhere with some areas
out east remaining in the 70s. RH`s will be in the 30s and 40s
through Tuesday before dropping back into the 20s by midweek. Best
chances for rainfall will be tonight areawide, then Sunday and
Monday mainly south and east of a line from Alamogordo to Las
Cruces. Vent rates will be good through the weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 69 88 70 81 / 40 30 30 50
Sierra Blanca 62 80 63 73 / 40 40 40 70
Las Cruces 64 87 65 81 / 40 30 40 40
Alamogordo 61 84 62 81 / 40 30 20 40
Cloudcroft 46 63 46 58 / 50 30 30 50
Truth or Consequences 62 87 62 84 / 30 20 30 30
Silver City 56 79 57 80 / 30 40 40 50
Deming 64 87 65 81 / 40 40 40 40
Lordsburg 62 87 63 85 / 30 50 50 40
West El Paso Metro 69 86 70 80 / 40 30 30 50
Dell City 65 84 66 79 / 50 40 30 60
Fort Hancock 67 87 68 80 / 40 40 40 70
Loma Linda 62 78 63 73 / 40 30 30 50
Fabens 67 86 68 80 / 40 40 40 50
Santa Teresa 66 85 67 79 / 50 30 40 50
White Sands HQ 67 84 68 81 / 40 30 30 50
Jornada Range 62 85 62 81 / 40 30 30 40
Hatch 62 88 63 80 / 40 30 30 40
Columbus 66 87 67 81 / 30 40 40 40
Orogrande 62 82 63 79 / 40 30 20 40
Mayhill 52 71 53 67 / 40 40 30 50
Mescalero 50 72 51 69 / 50 40 30 50
Timberon 49 70 50 66 / 40 30 30 40
Winston 52 79 53 77 / 30 30 30 30
Hillsboro 58 85 59 83 / 30 30 40 40
Spaceport 59 86 60 82 / 30 30 30 40
Lake Roberts 51 81 50 79 / 40 40 40 50
Hurley 57 82 58 81 / 30 40 40 40
Cliff 56 87 55 84 / 30 40 40 40
Mule Creek 55 82 54 82 / 30 40 30 40
Faywood 59 83 60 80 / 40 40 40 40
Animas 64 88 65 85 / 40 40 40 50
Hachita 62 85 63 82 / 40 40 40 40
Antelope Wells 62 84 63 82 / 30 40 40 50
Cloverdale 60 83 61 80 / 40 40 40 60
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...Flood Watch until 8 PM MDT this evening for NMZ415-416.
&&
$$
FORECASTER...41-Kelly
Area Forecast Discussion
National Weather Service Grand Rapids MI
925 PM EDT Fri Aug 30 2024
.KEY MESSAGES...
- Storms moving out tonight
- Quiet and cooler weather into Thursday
&&
.UPDATE...
Issued at 925 PM EDT Fri Aug 30 2024
The threat for thunderstorms has ended across our fcst area.
However an upper trough and mid to upper level pva over our
southern fcst area will bring some light rain showers to that area
overnight. This notion is suggested by the 00Z HRRR and 12Z HREF.
Some localized patchy fog may develop toward daybreak
particularly in areas where it rained earlier today. This
potential will be mitigated somewhat by fairly extensive cloud
cover which should linger for most of the overnight period.
&&
.DISCUSSION...
Issued at 325 PM EDT Fri Aug 30 2024
- Storms moving out tonight
We still expect strong to severe storms to form this afternoon
across the southeast forecast area from Lansing to Battle Creek
over to Jackson where 1500 to 2000 J/kg of CAPE will be available
for storms ahead of the shortwave trough approaching from the
northwest. Shear profiles show only about 20 to 25 knots of deep
layer shear so the main threat will be isolated damaging winds
from transient bowing structures or deeper updrafts/precip cores.
The stronger storms are expected to be clearing the southeast
zones by 8 pm but rain showers will linger across the southern
zones after midnight as another batch of showers out ahead of the
upper trough axis arrives later this evening.
- Quiet and cooler weather into Thursday
Confidence is fairly high that we will see a cooler, quiet, and much
less humid period from Sunday into next Thursday.
The upper trough that tries to clip our area Saturday night into
Sunday will usher in even cooler weather than the cold front coming
through today. Can not rule out a brief shower up North Sunday
morning, but it should not be anything to cause any issues.
Once the trough moves out by later Sunday, we will see a fairly high
amplitude upper ridge only slowly build toward the area through much
of next week. This will be slow to move through as the upper air
pattern will slow down with the amplified upper low developing as it
moves east of the area. Much drier air coming in, along with plenty
of subsidence downstream of the upper ridge will keep the area dry.
We will see mild days, and cool late summer nights with the temps
dropping quickly in the evening with the dry air in place.
It looks like our next chance for some rain will not arrive until
later Thursday into Friday. The bottle-necked upper air pattern will
shift to the east enough that the ridge slips east of the area. An
upper ridge will become established across the western states, and
allow a fairly large amplitude low/trough to dig over the area. This
will equal cooler weather coming in again, with some occasional
instability showers possible. Not sure if this trough/low anchors
over the area, or just slowly moves by just beyond this forecast
period next weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 747 PM EDT Fri Aug 30 2024
Showers and storms have moved east this evening and conditions
will stay dry until just after 06z at which point some light rain
will be possible. This will mainly impact terminal near the I-94
corridor until about 09z. Briefly reduced visibilities down to 4
to 5 miles is possible. VFR returns just before daybreak, then
high clouds and quiet weather for the rest of Saturday.
&&
.MARINE...
Issued at 325 PM EDT Fri Aug 30 2024
North winds behind a cold front on Sunday will gust to 30 knots
and build waves of 4 to 6 feet and perhaps higher by Sunday
afternoon. We have issued a SCA and Beach Hazard Statement already
given high confidence in this event during a holiday weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from late Saturday night through late
Sunday night for MIZ037-043-050-056-064-071.
MARINE...Small Craft Advisory from 4 AM Sunday to 1 AM EDT Monday for
LMZ844>849.
&&
$$
UPDATE...Laurens
DISCUSSION...Ostuno/NJJ
AVIATION...Thielke
MARINE...Ostuno
Area Forecast Discussion
National Weather Service Northern Indiana
731 PM EDT Fri Aug 30 2024
.KEY MESSAGES...
- Scattered to numerous showers and thunderstorms will develop
this afternoon through late evening. A few of these storms
might become strong with gusty winds and small hail.
- A High Swim Risk on Lake Michigan Beaches expected Sunday.
Otherwise, pleasant weather with drier and more mild
temperatures expected through Labor Day Weekend.
&&
.DISCUSSION...
Issued at 214 PM EDT Fri Aug 30 2024
It`ll be another warm and humid afternoon as mid/upper level
ridging holds on for one more day. Dewpoints in the upper 60s to
low/mid 70s where greatest evapotranspiration is occuring will
leave us feeling muggy in most locations. Drink plenty of fluids
if you plan on spending time outdoors during peak heating.
A cold front will begin to work its way through our area this
evening and through the overnight hours. Out ahead of this
front, scattered to numerous showers and thunderstorms (40-65%
chance) will develop. Environmental conditions do not appear
very conducive for robust severe thunderstorms. However, 15Z-
satellite and surface analysis shows an outflow boundary now
transecting our CWA, and 14Z forecast RAP suggests an area of
enhanced (but on the weak side) 0- 6km shear between 20-30kt,
along with moderate ML CAPE of 1500-2000 J/kg; residing mainly
south of US-6 and west of US-31. Assuming convection can
overcome some inhibition, which CAMs and model soundings suggest
will happen, some of these storms may produce small hail and a
strong to marginally severe wind gust late this afternoon into
evening, especially in the aforementioned area in N Central
Indiana.
Our weather for the extended 3 day weekend will be excellent
with high temperatures and relative humidity noticeably more
pleasant beginning Saturday. Labor Day itself will see the
coolest temperatures as lows bottom out around 50 degrees and we
only warm up into the low/mid 70s. Not cold, but much better
than earlier this week if I do say so myself. For Sunday, keep
an eye on tents/canopies/umbrellas as north to northwest winds
will be a bit breezy with gusts 20-25 mph, especially across
northwest IN and southwest MI.
Unfortunately, the cooler north winds won`t bring completely
good news. We have high confidence in a High Swim Risk for
southeast Lake Michigan beaches on Sunday as wave heights will
grow to near 6 feet. These waves and currents might trickle into
Monday, so be sure to check your local beaches on Monday; and
avoid swimming at all on Sunday.
Dry and mild weather will continue through much of the work
week before models hint at an amplifying pattern with troughing
occuring across the Great Lakes region. Will let model blended
PoPs ride on Friday with the expectation that an unstable
airmass and possible front might be in the vicinity, making
isolated chances (15-20%) sound reasonable.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 729 PM EDT Fri Aug 30 2024
A cold front creeps southeastward this evening and overnight
allowing for a chance for some thunderstorms. The storms are
expected to lose their severity as we head towards and past sunset
this evening. Then a reinvigoration of rain and perhaps some thunder
takes shape farther southwest, south of US-30, after 00z or so
tonight. Can see those affect FWA by midnight or so tonight. Will
have vcts to start, but will have shra in there for later.
There`s some question about fog potential tonight as the temperature
and dew point drop slows with the arrival of the rain. Still will
hang on to the lowered VISBY chance at FWA, but will also leave it
off of SBN as the previous issuance did.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement from Sunday morning through Monday
morning for INZ103.
OH...None.
MI...Beach Hazards Statement from Sunday morning through Monday
morning for MIZ177-277.
MARINE...Small Craft Advisory from 8 AM Sunday to 2 AM EDT Monday for
LMZ043-046.
&&
$$
DISCUSSION...Norman
AVIATION...Roller
Area Forecast Discussion
National Weather Service North Platte NE
541 PM CDT Fri Aug 30 2024
.KEY MESSAGES...
- Tranquil and dry conditions continue through much of next week
with temperatures at or slightly above normal.
&&
.SYNOPSIS...
Issued at 301 PM CDT Fri Aug 30 2024
Recent GOES-16 WV imagery and RAP 500-mb analysis showed high
pressure anchored across the Desert Southwest with a ridge
extending northwest into the Pacific Northwest. A secondary
upper-level high was noted across the southeastern CONUS with a
ridge extending northeast into northern Quebec. An upper-level
low pressure system was swinging northeast into the Hudson Bay
with a trough extending south into the northern Plains, Midwest,
and Great Lakes regions. At the surface, high pressure was
apparent across the northern Plains. A beautiful end of August
day has been observed across western and north central Nebraska
with 3 PM CT temperatures ranging from 77 degrees at O`Neill to
86 degrees at Valentine.
&&
.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 301 PM CDT Fri Aug 30 2024
Pleasant conditions continue through the first half of Labor Day
weekend and beyond. The previously mentioned surface high will hold
strong over the region tonight into Saturday with clear skies and
light winds prevailing. Mid-level warm air advection (WAA) will
result in near seasonal overnight lows in the low to mid-50s. An
upper-level disturbance currently located ~800 miles off the coast
of northern California will begin to slowly advance eastward,
nudging the southwestern CONUS ridge further east across the local
region. As a result, strong heating will occur ahead of a dry cold
front dropping southward out of the Dakotas with afternoon
temperatures climbing into the upper-80s to low-90s on Saturday.
Afternoon humidity values will fall to 20 percent or less across the
Sandhills (Fire Zones 204 and 206), however, relatively light winds
will limit fire weather conditions from reaching critical levels.
The aforementioned cold front will sweep through the area overnight
on Saturday with Canadian high pressure building in it`s wake.
Comparative to tonight, overnight temperatures on Saturday will fall
into the 50s.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 301 PM CDT Fri Aug 30 2024
We will very much be in a forecast loop through much of the long
term period as dry conditions and slightly above normal temperatures
continue. The exception to this will be the last day of the holiday
weekend being a breezy one as the surface pressure gradient (SPG)
tightens between a surface low across Montana and the strong surface
high holding strong over the Midwest. As a result, southerly winds
will strengthen overnight Sunday with wind gusts of 25 to 30 mph for
most locations, though the strongest gusts up to 35 mph will be felt
across the northwest Sandhills. Outside of the winds, a near picture
perfect Labor Day is in store for the area with daytime temperatures
ranging from the low-80s across north central Nebraska to low-90s
across the Sandhills. Given the above normal temperatures across the
Sandhills, afternoon humidity values will fall to 20 percent or
less. Combined with the breezy winds, elevated to near critical fire
weather conditions may materialize across Fire Zone 204. An almost
copy and paste forecast is on tap for Tuesday with the expansive
upper-level ridge holding strong over the central CONUS.
Fortunately the upper-level ridge will be forced to flatten as
the disturbance currently deepening across the Pacific Ocean
advances inland across the Great Basin into the northern Rockies
on Wednesday. This will drive a surface cold front into the
area by Wednesday evening, allowing highs to trend back into the
low to mid-80s through the remainder of the week and
potentially triggering a few showers or thunderstorms Thursday
into Friday. Confidence is rather low on precipitation chances
during this period and many locations aren`t likely to see much
in the way of wetting moisture. Given the spread amongst model
solutions, cannot argue with the NBM`s forecast of sporadic
slight chance/chance PoPs.
&&
.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 540 PM CDT Fri Aug 30 2024
VFR conditions with SKC expected across central and western
Nebraska through the valid period. With afternoon dew points in
the 40s and expected lows tonight a few degrees warmer than last
night do not anticipate meeting our crossover temperature for
fog formation and guidance is in good agreement in generating no
fog or stratus. Perhaps some shallow fog right near lakes and
rivers but do not anticipate any negative impacts at TAF sites.
Winds will be light through daybreak Saturday morning. Expect light
southwesterly winds will persist at KLBF at or below 10kt through
Saturday afternoon. However KVTN will see a weak, dry front drop
down form the north and swing winds around to a northerly/northwesterly
direction during the afternoon with some gusts around 20kt.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...MBS
Area Forecast Discussion
National Weather Service San Francisco CA
621 PM PDT Fri Aug 30 2024
...New UPDATE...
.SYNOPSIS...
Issued at 1252 AM PDT Fri Aug 30 2024
Cool temperatures persist through the Labor Day Holiday. A warmup
looms for Tuesday of next week and beyond.
&&
.UPDATE...
Issued at 614 PM PDT Fri Aug 30 2024
The latest HRRR vertically integrated smoke product shows a fairly
strong signal that smoke from the Coffee Pot Fire in Tulare County
will push through the East Bay and Napa County overnight and into
Saturday morning. This is supported by visible imagery showing a
clear band of smoke heading that direction. Fortunately the near-
surface smoke concentrations look minimal and this will be more
of a sunrise maker than anything else. Otherwise, the stratus has
totally evaporated across the area and clear skies prevail.
Despite this, the models have a strong signal for it to return to
coastal areas overnight. They are likely a little too aggressive
with the timing based on comparing the current analysis with
satellite imagery and we adjusted the sky grids and aviation
forecast to show a later arrival.
&&
.SHORT TERM...
(This evening through Saturday)
Issued at 1214 PM PDT Fri Aug 30 2024
Satellite imagery shows stratus blanketing the Monterey Bay region
and pared back to the immediate coast everywhere else. Further
mixing out of the stratus will continue in the Monterey bay region
through the early afternoon hours, but patches of stratus will
remain through the day at the immediate coast. Once again,
widespread stratus coverage is expected to return tonight as the
marine layer remains robust at 1500-2000 feet.
Temperatures remain near seasonal averages as a cutoff low
approaches the region, eating into an upper level ridge that is
migrating towards the northwestern United States and southwest
Canada. High temperatures today and Saturday will range from the mid
80s to the mid 90s across the inland valleys, up to near 100 in the
southern extremes of Monterey County, the low 70s to lower 80s along
the bays, and the low to mid 60s along the Pacific Coast. Lows range
in the 50s and lower 60s in the lower elevations, perhaps up to the
low 70s in the peaks. Onshore winds will continue to be breezy
during the afternoons and evenings, gusting up to around 20-25 miles
per hour in the gaps, passes, and Salinas Valley.
&&
.LONG TERM...
(Saturday through Thursday)
Issued at 1252 AM PDT Fri Aug 30 2024
The troughing continues through the weekend and Labor Day
with below-normal temperatures expected. However, Monday, Labor Day,
will see just a slight uptick in high temperatures as ridging (high
pressure) redevelops over the region, leading us into our next
period of warm weather. But, for the sake of Labor Day activity
planning, lets provide a quick rundown of what you can expect
weather-wise for the day:
-Interior regions will see highs in the upper 80s and low 90s.
Here`s a sample of highs expected for a handful of cities on Monday:
Concord 88, Livermore 86, SF downtown 73, SF Ocean Beach 62, Santa
Rosa 84, Napa 82, Gilroy 90, Monterey 69, Santa Cruz downtown 79,
King City 88.
-Clear skies, minus some overcast conditions in the morning at the
immediate coast until the stratus clears in the afternoon.
-Light onshore winds in the afternoon, with breezier conditions near
coastal gaps as the seabreeze picks up in the afternoon.
All in all, it should be a pleasant day for anyone that is perhaps
planning any activities outdoors for the holidays. Being one of
the last big summer holidays where temperatures are still warm
outside, many people may be planning to hit the water. As always,
we want to encourage people to be safe, so if you`re planning on
going boating or swimming at the lake, or even just having a BBQ
on the shore, remember to wear that life jacket, know the risks
of cold water shock, swim near a lifeguard, and check local ocean
or waterway conditions before you go.
Beyond the holiday, warm temperatures persist, with the ridge
building Tuesday and beyond to allow for the return of above normal
temperatures. At this point, no products have been issued for heat.
All for now.
&&
.AVIATION...
(00Z TAFS)
Issued at 511 PM PDT Fri Aug 30 2024
VFR across the board becoming MVFR-IFR overnight. Stratus is
expected to be widespread with moderate confidence in MVFR CIGs and
slightly lower confidence in any MVFR CIGs that do develop lowering
to become IFR. Main difference from previous set of TAFs - pushed
back stratus arrival time for most airports with most sites expected
to return later tonight beginning around/after 05-06Z. Currently not
anticipating stratus to reach LVK but temporary MVFR-IFR CIGs remain
possible during the early morning 11-16Z timeframe. Stratus will
clear out by mid to late morning with all sites returning to VFR
through the remainder of the TAF period and into the afternoon.
Winds generally stay west to northwest through the TAF period with
more moderate daytime winds and weaker winds overnight.
Vicinity of SFO...VFR becoming MVFR overnight. The timing of stratus
arrival was pushed back slightly with arrival between 08-10Z looking
more favorable. MVFR CIGs are expected to persist through mid
tomorrow morning with low confidence that IFR CIGs will develop.
Moderate northwest winds with gusts up to 25 knots persist during
into the evening before winds weaken and become more west-
northwesterly overnight. Northwest winds are expected to strengthen
tomorrow afternoon with gusts up to 23 knots possible.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR becoming MVFR-IFR overnight. Pushed
back the timing of stratus arrival to 05-06Z with ensemble guidance
and current satellite observations supporting a later return of
stratus. Moderate confidence that CIGs will first develop as MVFR
and gradually become IFR. Low to moderate confidence on timing of
transition due to models overestimating stratus coverage and
forecasting too low CIG heights. Any stratus that does develop will
dissipate by mid to late morning, going off persistence around 18-
19Z, with VFR through the remainder of the TAF period. Moderate
northwest winds persist during the day before winds become lighter
and more variable overnight.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 511 PM PDT Fri Aug 30 2024
Breezy to gusty west winds will funnel through the Golden Gate
into the northern San Francisco Bay the both today and again
tomorrow, especially during the afternoon and evening hours.
Locally stronger wind gusts will be likely in the nearshore waters
south of Pigeon Point for Saturday afternoon. Northwesterly winds
will redevelop over the coastal waters late in the upcoming
weekend resulting in increasing seas.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Saturday for SF Bay N of Bay
Bridge.
Small Craft Advisory from 3 PM Saturday to 3 AM PDT Sunday for
Pt Pinos to Pt Piedras Blancas 0-10 nm-SF Bay N of Bay
Bridge.
Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pigeon
Pt to Pt Pinos 0-10 nm.
&&
$$
SHORT TERM...DialH
LONG TERM....AC
AVIATION...Kennedy
MARINE...Flynn
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Area Forecast Discussion
National Weather Service Spokane WA
440 PM PDT Fri Aug 30 2024
.SYNOPSIS...
A ridge of high pressure will build over the region through the
rest of the week. The Labor Day weekend will feature much warmer
than average temperatures with most of the Inland Northwest
exceeding 90 degrees Saturday, Sunday and Monday. The arrival of a
cold front Monday night into Tuesday will bring breezy conditions
and the chance for showers and thunderstorms. Hot temperatures
look to return over the Inland Northwest for the latter half of
next week as the ridge of high pressure rebounds.
&&
.DISCUSSION...
Key points:
- Temperatures will be 10-20 degrees above normal through Labor Day
weekend.
- 15-30% chance of thunderstorms in southeast Washington and north
Idaho Monday afternoon. Slight cooling trend to near normal
temperatures Tuesday.
- Upper level ridge rebuilds by Wednesday. Temperatures return to
much above normal.
Tonight through Tuesday: A ridge of high pressure will continue to
build through the weekend, bringing very warm temperatures to the
area. Temperatures are expected to be in the mid-to-upper 90s
across the majority of the area with small pockets of triple
digits, particularly near Lewiston. With skies expected to be
clear, insolation will be maximized, with the warmest temperatures
expected to be on Sunday before the trough off the coast of
California begins to aid in ridge breakdown. Nonetheless, a
moderate to major heat risk will persist through Monday. Given the
holiday weekend and associated increase in outdoor activities, it
is crucial that people take precautions. Dry conditions will also
increase the rate of dehydration. Avoid strenuous activity, bring
along and drink plenty of water and electrolytes, take advantage
of shade and air conditioning, and be sure to check in on any
vulnerable friends, family, or neighbors and provide any necessary
assistance.
As the trough off the coast of California begins to move ashore
Monday morning, the ridge will begin to break down. Concurrent
precipitable water anomalies of up to 60% above normal will be
present on Monday and Tuesday. Unfortunately, the bulk of this
precipitable water will be above 600 mb, with very dry air beneath
it. LCL heights are forecast around 13000 to 14000 feet during
this time. This will significantly limit the ability of any
precipitation to reach the ground. Global ensemble members are
forecasting SBCAPE up to 500 J/kg across much of Washington and
northern Idaho on Monday, and up to 1000 J/kg in northern Idaho on
Tuesday. This, combined with the aforementioned dry lower-level
conditions, will create a low threat of dry lightning in the
respective areas during this period. Wetting rain probabilities
will be no higher than 5% on the lee side of the Cascades and 10%
in northern Idaho late Monday. DCAPE values of up to 1,200 J/kg
will also create a risk of gusty outflows. With low relative
humidities (teens) and breezy winds (5-10 mph with gusts up to 20
mph). A minor fire risk will be present, particularly near any
lightning strikes. The area of maximum concern for fire weather
will be southeast Washington and north Idaho.
Tuesday will bring a brief respite from the heat as the shortwave and
cold front move through, with the convective risk moving eastward
into eastern Shoshone county. Models are not yet in agreement on
when the shortwave will fully clear the area, which may allow the
convective risk to persist later on Tuesday, particularly in
extreme eastern Washington and northern Idaho. High temperatures
will dip to the upper 80s across most of the area.
Wednesday through Friday: Ridging will quickly build back on
Wednesday, allowing temperatures to rebound to at least the mid
90s. The peak intensity of the ridge is not yet clear, but there
is a decent chance it could be equally potent or even slightly
more so, which will make heat a significant concern during this
period. Ensembles are split about 50/50 on the ridge axis staying
over the Inland Northwest or shifting east. This will affect the
timing and duration of increased temperatures, with the majority
of members not showing a return to normal heights until Sunday or
even Monday. This means we can likely expect temperatures in the
90s at least through next weekend, which may necessitate further
Heat Advisories. /Cooke
&&
.AVIATION...
00Z TAFS: Increasingly warm high pressure will build over the
Pacific Northwest through Sunday. Mainly clear skies and light
winds will be the prevailing condition through at least Saturday
night.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
for VFR conditions through 00z Sunday. The HRRR Total Smoke
forecast is bringing smoke into far southeast Washington and the
Idaho Panhandle Saturday night into Sunday. It will probably be
aloft initially, but by Sunday night into Monday deeper mid and
low level southerly winds may begin to degrade visibility around
Lewiston and Pullman. Confidence low. /GKoch
-----------------------
Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70
percent chance
High - Greater than a 70 percent chance
For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https:/www.weather.gov/otx/avndashboard
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 54 93 58 95 61 90 / 0 0 0 0 0 10
Coeur d`Alene 53 90 56 92 58 90 / 0 0 0 0 0 0
Pullman 51 91 55 95 57 86 / 0 0 0 0 0 20
Lewiston 59 98 63 100 64 92 / 0 0 0 0 0 10
Colville 47 91 50 95 53 92 / 0 0 0 0 0 0
Sandpoint 51 86 54 90 55 89 / 0 0 0 0 0 0
Kellogg 58 89 60 92 63 90 / 0 0 0 0 0 10
Moses Lake 53 95 56 97 62 91 / 0 0 0 0 0 0
Wenatchee 64 93 68 97 71 91 / 0 0 0 0 0 10
Omak 59 95 62 98 64 94 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Heat Advisory from 11 AM Saturday to 9 PM PDT Monday for Central
Panhandle Mountains-Coeur d`Alene Area-Northern Panhandle.
Heat Advisory from 11 AM Saturday to 9 PM PDT Sunday for Idaho
Palouse-Lewiston Area.
WA...Heat Advisory from 11 AM Saturday to 9 PM PDT Monday for
Northeast Mountains-Spokane Area.
Heat Advisory from 11 AM Saturday to 9 PM PDT Sunday for Central
Chelan County-Lower Garfield and Asotin Counties-Moses Lake
Area-Okanogan Highlands-Okanogan Valley-Upper Columbia
Basin-Washington Palouse-Waterville Plateau-Wenatchee Area-
Western Chelan County-Western Okanogan County.
&&
$$
Area Forecast Discussion
National Weather Service Reno NV
144 PM PDT Fri Aug 30 2024
.SYNOPSIS...
* Weekend: Seasonably warm and dry with isolated showers or T-storms
possible across the Eastern Sierra Saturday afternoon.
* Breezes ramp up on Sunday with widespread gusty winds for Monday
with impacts to recreation, fire weather, and aviation possible.
* Temperatures drop to near season averages for the first half of
next week before warming up again.
&&
.DISCUSSION...
This Weekend:
* Temperatures remain seasonably warm (4-8 degrees above average) as
we sail into the holiday weekend with high temperatures in the mid-
90s across western Nevada and mid-80s for Sierra communities.
Through Sunday there will be a few spots of moderate HeatRisk
possible for rural areas and in urban centers, so remember to stay
hydrated and keep cool in the shade when you can.
* Afternoon heating will produce afternoon instability across the
eastern Sierra with some afternoon cumulus buildups as well as some
isolated showers or thunderstorms. The best potential holds steady
for Saturday afternoon with a 10-15% chance for a few showers or
an isolated thunderstorm for the Eastern Sierra south of
Highway 50.
* Winds will generally remain light through Saturday before
breezier southwest winds return on Sunday (20-25 mph gusts)
ahead of an approaching offshore low that will make its way
inland Sunday night into Monday. This low may provide enough
forcing aloft to develop fast moving, elevated showers (15%
chance) across far E.Modoc and far N.Washoe counties.
* Latest HRRR near surface smoke projections are showing some smoke
inching across the Eastern Sierra into Mammoth Lakes, June Lake
and the Mono Lake vicinity early Sunday morning.
Labor Day Brings Gusty Wind Impacts:
* Forecaster confidence holds steady as a well-forecast upper low
approaches the West Coast this weekend. Plan on increasing winds
Sunday into Monday that will bring impacts to aviation, recreation
and elevated fire weather concerns.
* The strongest winds arrive Monday afternoon, with a 40-50% chance
of gusts 40+ mph for the eastern Sierra into northwest and far
western NV, including the US-395/I-580 corridor. Sierra ridgetops
will also see increased winds beginning Sunday evening with gusts
of 50-60 mph through Monday.
* Plan on areas of critical fire weather conditions with the arrival
of the gusty winds combining with the very dry conditions. For
more see the fire weather section. The strong winds may produce
blowing dust, aviation turbulence and rough lake conditions for
those recreating for the holiday weekend. Plan ahead for the
strong winds and have a plan B. Blowing playa dust could impact
aviation and produce low visibility for those driving out of Black
Rock City from Sunday into Monday evening.
* Other than these unpleasant (IMO) impacts, it will cool down a bit
in the wake of this quick system. Plan on closer to seasonal
averages for the first half of the week before warming back around
5 degrees above average for the second half of the week. Next week
looking pretty dry with typical light afternoon breezes.
Edan
&&
.AVIATION...
* VFR conditions with typical southwest winds will continue through
Saturday. Afternoon cumulus cloud development is possible across
the E.Sierra with a 15% chance for showers or an isolated
thunderstorm along the E.Sierra from KTVL to KMMH Saturday
afternoon (15% chance).
* Smoke from fires west of the Eastern Sierra (mainly Coffee Pot
fire) will infiltrate into the the KMMH vicinity and may produce
slantwise visibility reductions early Sunday morning.
* Winds increase on Sunday into Monday with gusty southwest winds
Sunday (20kts) ramping up more Monday (25-30kts). There will
likely be periods of moderate turbulence and LLWS issues for area
terminals. Edan
&&
.FIRE WEATHER...
Confidence continues to increase for widespread critical fire
weather conditions over northeast California and far western Nevada
on Monday afternoon and evening. A low pressure system moving into
the region on Monday brings gusty southwest winds to 30-35 mph to
the aforementioned areas. These winds are expected to overlap with
RH values in the single digits to low teens, resulting in a 3-6 hour
period of Red Flag conditions. Especially considering increased
outdoor recreation this weekend, we have hoisted a Fire Weather
Watch valid Monday afternoon and evening for CA zones 278 & 270 as
well as NV zones 420 & 458.
Ahead of this system, southerly flow transports just enough moisture
into the region to allow some isolated showers and thunderstorms to
develop generally south of US-50 on Saturday. As these storms will
be mainly dry, lightning starts are possible, though the isolated
nature of these storms precludes any product issuance. Winds begin
to tick up across areas generally north of I-80 as early as Sunday
afternoon, with gusts 25-30 mph. Gusty winds become more widespread
on Monday. Whitlam
$$
.REV Watches/Warnings/Advisories...
NV...Fire Weather Watch from Monday afternoon through Monday evening
NVZ420-458.
CA...Fire Weather Watch from Monday afternoon through Monday evening
CAZ270-278.
&&
$$
Area Forecast Discussion
National Weather Service Las Vegas NV
740 PM PDT Fri Aug 30 2024
.SYNOPSIS...A modest moisture increase will increase precipitation
chances in northwestern Arizona as well as the mountains of far
southeastern California and southern Nevada today and Saturday, with
chances dwindling, but not fully disappearing in Mohave County
through next week.
&&
.UPDATE...Scattered showers and thunderstorms developed across
Mohave and Clark County as well as eastern portions of San
Bernardino County this afternoon in response to a weak upper level
disturbance. Closer to the surface, mesoanalysis showed moisture was
still lacking and instability was weak, thus convection remained
isolated and impacts were limited. Some storms were able to produce
gusty outflow winds of 30-40 MPH, which make sense with dry invert-V
soundings providing a good environment for evaporative cooling but
limited instability that remained in the mid to upper levels keeping
DCAPE and downburst potential low. Now with the sun setting,
precipitation is quickly waning. A few showers are still noted on
radar but overall they are on a downward trend. The latest HRRR has
all precipitation ending by 9PM or 10PM and this seems reasonable.
Overnight should be dry, which is what the forecast has been
advertising so no changes were needed to the overnight forecast. One
thing that will be important to watch through the overnight hours is
how much debris clouds hang around which could not only keep low
temperatures from dropping off in western Arizona and southern
Nevada, but if debris clouds linger through Saturday morning they
could play a role in how much precipitation develops Saturday
afternoon. While there will be an increase in PWATs overnight and
the upper level disturbance will remain over the region for
Saturday, could clouds keep from maximum convective potential? Stay
tuned!
-Nickerson-
&&
.PREVIOUS DISCUSSION...228 PM PDT Fri Aug 30 2024
.SHORT TERM...Today and Tomorrow.
A weak shortwave trough will lift into the area from the Gulf of
California today, moving trough the area tomorrow. This disturbance
will bring a slight uptick in moisture to the region, helping to
fuel afternoon showers and thunderstorms across the eastern portions
of our forecast area today and tomorrow. Mohave County will have the
best chances of precipitation each afternoon with a 20 to 40% chance
of showers and thunderstorms this afternoon and a 30 to 60% chance
tomorrow afternoon. The higher terrain of southern Clark County and
the Mojave Preserve will see around a 15% chance of precipitation
this afternoon with a 20 to 30% chance of showers and thunderstorms
on Saturday afternoon. We will also see an uptick in precipitation
chances on Saturday afternoon for the higher terrain of Lincoln
County, with a 15 to 20% chance of showers and thunderstorms.
While we are expecting moisture to increase, we aren`t expecting a
highly anomalous push of moisture with precipitable water values
pushing 200% of normal. Average precipitable water values for late
August/early September are around 0.65 to 0.75 inches. This
morning`s 12Z sounding measured 0.75 inches of precipitable water.
All of this to say that widespread flash flooding is not expected to
pose a major threat with this afternoon`s storms, unless storms
begin training or remain anchored to the terrain. Dry low-levels
will also contribute to the decreased flash flood risk by making
it more difficult for rain to make it to the ground without
evaporating. However, these drier low-levels will result in an
increased risk of outflow winds from any storms that develop.
Outflow winds this afternoon are not expected to exceed 50 mph.
However, the same can not be said for storms tomorrow afternoon.
The 12Z HREF shows a 10 to 20% chance of 50+ mph outflow wind
gusts with storms in Mohave County tomorrow. Those recreating
outdoors, especially those recreating on area lakes, should make
sure to stay weather aware tomorrow.
.LONG TERM...Sunday through next Friday.
A shortwave will move into northern California on Sunday, which will
turn the flow more west to southwest. Despite modest PWATs remaining
over much of the area, this change in flow combined with limited
forcing and instability will limit precipitation potential and
impacts on Sunday to the terrain in eastern Mohave County.
As the low lifts northwest into the Northern Plains the beginning of
next week, breezy winds are expected Monday in the southern Great
Basin. Impactful gusts over 40 MPH are not likely, but will need
to watch the potential for increased fire danger due to winds and
low relative humidity. By Tuesday, the shortwave lifts away and
winds will diminish. Meanwhile, an area of high pressure will
reposition itself west over the Southwest US. This will decrease
moisture and precipitation chances while increasing temperatures.
There is a high probability (80% or greater) for above normal high
temperatures through the period in areas outside of the southern
Great Basin where the influence of the shortwave will keep
temperatures near normal through Tuesday before warming to above
normal by Wednesday. Heat Risk the second half of next week will
increase with potentially High Risk for heat-related impacts
returning in valley areas of San Bernardino, Mohave, Clark, and
southern Nye counties.
&&
.AVIATION...For Harry Reid...Northeast to East winds around 7-8kts
will prevail through 21z before shifting more to the Southeast with
speeds around 7kts. Southerly winds are forecast to develop during
the early evening, but there will be some potential of seeing
thunderstorm outflow winds between 23z-03z this evening that could
bring more variable and briefly gusty winds to the terminal. Overall
confidence is low and was not included in the TAF. Although no
thunderstorms are expected in the Las Vegas Valley, scattered
showers and thunderstorms are expected this afternoon and evening
across northwest Arizona affecting the Peach Springs and Mormon Mesa
corridors.
Similar conditions are expected Saturday with most of the convection
confined to northwest Arizona, but various outflow boundaries could
affect the winds at KLAS during the late afternoon and early
evening.
For the rest of southern Nevada, northwest Arizona and southeast
California...Most areas will see a continuation of the typical
diurnal wind pattern through Saturday. At KBIH, winds will be
southeasterly to south and remain until turning back to the north by
late this evening. Speeds will be 10-20kts. Winds around KDAG will
generally favor a northeast direction, but remain under 10kts. In
the lower Colorado River Valley, winds will remain southerly 10kts
or less through the afternoon. A few areas of convection are
possible over northwest Arizona this afternoon and evening, and
guidance continues to show a period of non-typical easterly winds
affecting KIFP for a few hours after 00Z. Away from the before-
mentioned convection, VFR conditions will prevail through tonight,
with only a few clouds with bases AOA 12kft AGL expected across
northwest Arizona, far southern Nevada, and far eastern California.
Conditions look to remain nearly the same Saturday with isolated
convection over northwest Arizona along with various outflow
boundaries that could impact KIFP and KEED late afternoon and
evening. There is a low probability of any outflow winds reaching
the Las Vegas Valley.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM...Stessman
LONG TERM...Nickerson
AVIATION...Gorelow
For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter