Lake Havasu City, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

583
FXUS65 KVEF 160351
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
900 PM PDT Tue Apr 15 2025

.SYNOPSIS...Today through midweek, expect similar temperatures. Late-
week, a dynamic weather system moves into the region, which will
increase chances of precipitation, gusty winds, and will cool off
temperatures substantially.
&&

.UPDATE...Shallow convection continues across the southern Great
Basin and northern Mohave County this evening. Dry low levels have
prevented much of this precipitation from reaching the ground. As
the sun sets, this activity will wane. Similar convection is
anticipated tomorrow across the southern Great Basin and Sierra,
though a stray shower or two cannot be ruled out on the Spring/Sheep
ranges or northern Mohave County. Activity becomes more pronounced
and widespread on Thursday and Friday as a cold front sags into the
area. Scattered showers and isolated thunderstorms are likely, with
graupel and/or small hail possible in the strongest cores.
Additionally, winds will increase while temperatures fall to below-
normal values. Over the weekend and into next week, things dry out
as temperatures moderate to seasonal values.
&&

.SHORT TERM...Through Wednesday Night.

Any showers that develop in the Southern Great Basin this afternoon
should diminish this evening as vorticity advection and any weak
diurnal instability wanes. The area will remain under diffluent flow
aloft, but the flow will turn southwest (compared to the south to
southeast we had this morning), which should advect dry air into the
region. However- abundant mid to upper level moisture will lead to
increasing clouds overnight.

The upper level low currently sitting of the southern California
Coast will begin to move inland on Wednesday. This will bring
continued strong upper level forcing with upper level diffluence,
and the return of increased vorticity advection. However, there is
some model disagreement in how much moisture will be available.
Currently, the ECMWF seems to be the outlier with 0.1-0.2 higher PWAT
compared to most other models, though the GEFS seems to be trending
in that direction. Overall, the models are most consistent that
there will be above normal PWATs over Inyo, Esmeralda, and western
Nye counties Wednesday afternoon, so this is the highest chance for
precipitation. Models are less consistent on how anomalous PWATs
will be further east through Central Nye and Lincoln counties-
precipitation will still be possible given the amount of forcing but
confidence is lower. Overall though- impacts will remain limited.
The 90th percentile QPF for Wednesday afternoon keeps rainfall
amounts under 0.10 inches even in Inyo and Esmeralda counties and
barely hits 0.25 inches on the Sierra peaks. Given the amount of
forcing, I think we will be able to squeeze out some showers from
Inyo through the Southern Great Basin Wednesday afternoon, but it
wont amount to much or cause significant issues. Snow levels
Wednesday remain very high around 8000ft or higher, so snow will
also be limited.

This general setup continues through Wednesday night, though forcing
should wane slightly as the Southern California low begins to weaken
and lift out. However, Wednesday night will be when a trough digging
out of the Pacific Northwest will potentially start to phase with
this low, which could keep low precipitation chances going in the
Southern Great Basin. Any precipitation impacts with this stronger
trough will be likely be Thursday onward, not during the Wednesday
night timeframe. West to southwest winds will increase in response
to the incoming system Wednesday night, mainly in the Western Mojave
Desert where the low level jet most intensifies. There is a 50%-60%
chance for impactful wind gusts over this area through the night,
though again better chances for impacts will be Thursday or later.
Temperatures Wednesday and Wednesday will start their downward
trend, but will only be a few degrees cooler than today and will
remain above normal.

.LONG TERM...Thursday through Monday.

The closed low and northern shortwave trough begin to phase on
Thursday, resulting in a larger, positively-tilted trough over the
western US. At the surface, guidance shows a cold front sliding
southward through the southern Great Basin and northern Mojave
Desert. The frontal boundary should serve as the focus for
precipitation as moisture pools along ahead of it and underneath
the colder air aloft. Expecting scattered shower and isolated
thunderstorms to develop along the front Thursday afternoon, with
activity potentially continuing Thursday night and Friday as the
front sags southward. There`s a fair amount of uncertainty in
model guidance regarding the convective environment Thursday-
Friday, mainly due to discrepancies in the magnitude of low-level
moisture and its overlap with the coldest air aloft. However, it
is likely that at least modest instability (100+ J/kg) will occur.
With wet bulb zero heights roughly 4500-6000 ft AGL in forecast
soundings, would not be surprised to see graupel and/or small hail
with the more intense convection. While PWATs are forecast to be
above the 90th percentile of climatology, this is nothing like
monsoonal moisture, so it`ll take training storms to cause any
flood concerns, and that would likely be localized and relatively
minor. On the wintry side, snow levels drop from over 8000 ft down
to ~6500 ft, so some late-season minor snow accumulations are
likely in the Spring Mountains and Sierra.

Other than the precipitation chances, noteworthy changes to the
weather include gusty winds and below-normal temperatures. Strongest
winds are expected Thursday, with minor wind impacts likely (70%
chance) across western San Bernardino County. Elsewhere, chances for
wind impacts are 30-50%, with widespread gusts of 25-40 mph
expected. Once the low closes off over our area on Friday, the risk
for impactful winds decreases. Temperature-wise, highs return to
seasonal values on Thursday but drop 5-15 degrees below normal on
Friday.

As this system pushes east and moves out over the weekend, dry
conditions return and temperatures moderate. By Sunday-Monday,
temperatures are forecast to be near-normal for mid-April. While
we`ll likely stay dry, the pattern doesn`t necessarily go quiet
next week as subsequent weak troughs may induce Springtime winds.

&&

.AVIATION...For Harry Reid...For the 06Z Forecast
Package...Light southerly drainage winds are expected overnight with
mostly clear skies. Southeast winds will return again tomorrow
afternoon, although speeds are forecast to be higher than earlier
today, with a greater than 50 percent chance of gusts to 20 knots
during the afternoon. VFR conditions will prevail tomorrow, with
mainly SCT skies with bases AOA 15kft AGL through the period.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 06Z Forecast Package...Conditions at the Las
Vegas area TAF sites will be similar to what is described for Harry
Reid above, except winds at KHND are expected to remain more
southerly throughout the period.  Elsewhere, winds will tend to
follow typical diurnal direction trends with a few gusts to 25kts
possible at KDAG tonight.  Most sites will see gusty south-to-west
winds develop tomorrow afternoon.  VFR conditions will prevail
across the region through tonight, with mainly FEW to SCT skies with
bases AOA 15kft AGL.  Clouds will thicken along the Sierra tomorrow,
and a few isolated showers will be possible after 21Z near and west
of KBIH.

&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.

&&

$$

UPDATE...Woods
SHORT TERM...Nickerson
LONG TERM...Woods
AVIATION...Planz

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