791
FXUS65 KVEF 251722
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1022 AM PDT Tue Jun 25 2024

.SYNOPSIS....Moisture will spread northward today, resulting in
scattered showers and thunderstorms through Clark, Lincoln, Inyo,
Mohave and San Bernardino counties. By midweek, low pressure will
push the moisture eastward, decreasing precipitation chances but
increasing winds Thursday and Friday. After a brief dip in
temperatures late-week, temperatures will climb again through the
weekend into early next week.
&&


.UPDATE...Expecting isolated convection across the forecast area
this afternoon, with CAPE values ranging from 500 to 1000 J/kg and
PWATs approaching 200% of normal. Best rain makers will form in
Mohave and southeastern Lincoln counties as moisture continues to
make its way into the low-levels of the atmosphere. Yesterday,
storms in eastern Mohave County observed around 1 inch of rainfall.
Storms in the higher terrain with little movement could produce
similar rain amounts in northeastern Arizona this afternoon. Low-
level moisture dwindles further north and west in the forecast area.
Thunderstorms are expected once again in Inyo County today, though
these are likely to have frequent lightning and strong gusty winds -
rather than high rain rates. As mentioned in the previous
discussion, storms will favor the higher terrain with the absence of
synoptic forcing. No changes were made to the forecast this morning
as it looks to be in good shape.
&&


.PREVIOUS DISCUSSION...146 AM PDT Tue Jun 25 2024/


.DISCUSSION...Through the Weekend.

Anomalous moisture will continue to push north today. By this
afternoon, PWATs will be over 200% of normal across the region,
with the axis of highest moisture pooling over San Bernardino,
Clark, and Mohave counties where probabilities for over 1.00 inch
PWATs is very high (90%+). With moisture spreading further north
than yesterday, expecting scattered showers and thunderstorms
further north as well, including in the Springs and Sheep Range as
well as in Lincoln County. Mohave County will continue to have
the highest risk for convection this afternoon as this is where
HREF is painting 50%-70% probabilities for surface CAPE over 500
J/Kg and the highest moisture will be available. Also expecting
another round of showers and thunderstorms in the White Mountains
and Sierra this afternoon that will be fairly similar to what
developed yesterday. Precipitation should favor the terrain as
there is a lack of a significant forcing trigger and instability
remains meager and elevated. Some models hint at an outflow
pushing in from central Arizona which could trigger more
thunderstorms cover in the valleys in eastern Mohave County this
afternoon around 3pm-7pm. The best chance for heavy rain and flash
flooding will be in Mohave County, but given the scattered and
unorganized nature of the convection this afternoon- the threat
should remain isolated. The main threat today will be gusty outflow
winds over 40 MPH. The highest risk for this will be in Inyo through
the southern Great Basin where downdraft CAPE will be highest and
the low levels will remain the driest.

Precipitation will diminish after sunset, though isolated showers
and thunderstorms could linger through the first part of the night
in Lincoln County. On Wednesday, the axis of anomalous moisture will
shift east as an incoming shortwave from the Pacific Northwest
shoves it out and replaces it with drier air. Afternoon shower and
thunderstorm chances will favor Lincoln and Mohave counties as areas
further west dry out somewhat. Similar threats are expected
Wednesday with isolated flash flooding possible but the main
concerns will be lightning and gusty winds.

For Thursday and Friday, the upper level trough will continue to dig
into the region and knock most of the moisture out and replace it
with drier air and cyclonic flow aloft. There is a low chance for
isolated showers and thunderstorms in far eastern Mohave County
where limited moisture could kick something off on Thursday-
however any impacts would be minor to none. By Friday, the area
will be dry. As the trough moves in and brings drier conditions,
it will also bring breezy southwest winds. The probability for
impactful wind gusts over 40 MPH is low (less than 30%) across the
region, however with drier air and breezy winds, fire danger will
increase. Forecast wind gusts of 20-35 mph on Thursday should
yield at least elevated fire danger, particularly in the lower
elevations where fuels have cured and afternoon RH values are
expected to be around 8-12%.

As we head into the weekend, the southern US ridge begins to extend
westward into the Desert Southwest. As a result, winds weaken while
temperatures rise again. There is some uncertainty in how warm
temperatures will be this weekend as models are struggling to
resolve how quickly the ridge builds back in and if it will have to
fight with another shortwave moving through the Pacific
Northwest. However, even with the large temperature spread noted
on long range ensembles, based on the monthly temperature data
thus far and the latest model guidance, Las Vegas will be hard-
pressed to NOT experience its hottest June on record. A little
number crunching shows that even if the 5th percentile of high/low
temperatures from the NBM verify these last 7 days, we`ll still
set the record. At this point, its not a matter of "if" but "by
how much" we break the warmest June record.
&&


.AVIATION...Setup looks very similar to past several days. The
current southerly wind will continue and eventually weaken by 16Z
this morning. From 16Z through about 22Z, the wind direction will
probably fluctuate between 130-180 degrees, before shifting more
out of 170-210 degrees after 22Z with gusts up to 20 knots this
afternoon. Also there is a low, but not zero, chance that a
thunderstorm outflow from the south or east may affect the
terminal around/or after 03Z this evening. If that does not occur,
typical south to southwest winds are expected overnight.

For the rest of southern Nevada, northwest Arizona and southeast
California...Thunderstorm chances are expected from Inyo and
Esmeralda counties eastward through Lincoln County and then south to
Mohave County and the mountains of Clark County. The Bishop terminal
has the highest probability of being affected by thunderstorms
today. The main concerns with storms will be erratic gusty winds,
brief heavy rain, along with lower ceilings below 8000 feet
occasionally obstructing the terrain. Away from storms, southerly
winds gusting 15 to 25 knots are expected.
&&


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

&&

$$

UPDATE...Soulat
DISCUSSION...Nickerson
AVIATION...Pierce

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