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Area forecast discussion 
National Weather Service Las Vegas Nevada
836 am PDT Tuesday Jul 22 2014

Synopsis...a more southerly flow today through Friday will lead
to a slight chance of thunderstorms over northwest Arizona. It will
be dry elsewhere with high temperatures running around 5 degrees
above normal. Moisture will eventually spread northwest into the
Mojave Desert and southern Great Basin over the weekend for an
increasing chance of thunderstorms.
&&

Update...quiet weather this morning. No update planned.
&&

Previous discussion...
240 am PDT Tuesday Jul 22 2014

Short term...through Friday night...a large area of high pressure
will be in place from the Southern Plains into the Desert Southwest
through the period. This will lead to hot and mostly dry conditions.
A more southerly flow than what we have been seeing will develop
starting today. This will lead to a bit of a moisture increase into
the area with moisture creeping slowly toward the northwest. At this
time we are keeping thunderstorm chances limited to Mohave County
through Friday but we will have to watch for the possibility of
something sneaking into Nevada and California due to outflow
boundaries and unforeseen upper level disturbances.

Long term...Saturday through Wednesday...high pressure ridge
centered over The Four Corners will become better positioned to
allow for a modest increase in monsoon moisture during the extended
period. Precipitable water values exceeding one inch begin to creep
into our northwest Arizona zones by late Saturday and expand to
encompass much of our forecast area on Sunday thanks to a
disturbance rotating around the high. Continue to have probability of precipitation limited
to Mohave County Saturday then expanding west Sunday and Monday. For
now I maintained probability of precipitation greater than 15 present mainly in the mountain
regions. A gradual drying may take place Tuesday Onward as the high
takes on a less favorable orientation centered over Arizona,
blocking the best moisture and instability from reaching the Mojave
Desert.

As far as temperatures go, latest European model (ecmwf) guidance continues to be at
odds with the major global models and best performing guidance,
insisting on temperatures exceeding 110 in Las Vegas Saturday Onward
(despite a marked increase in cloud cover and moisture). I
discounted the European model (ecmwf) guidance in favor of the cooler and better
performing model guidance. This will keep temperatures a few degrees
above normal but not excessively hot for late July in this part of
the world.

Aviation...for McCarran...an easterly wind will develop again this
morning before shifting to the south after 21z. Speeds through the
period will range between 6-11 kts. Some increase in high clouds is
expected later today and tonight. No significant cloud cover through
tonight.

For the rest of southern Nevada...northwest Arizona...and southeast
California...no significant weather affecting terminals through
tonight. Cloud cover will spread into northwest Arizona today and
continue slightly further west into the Colorado River valley
tonight and Thursday. There is a slight chance of a thunderstorm
over the plateaus of northern Mohave County this afternoon and
evening. Generally looking at south winds becoming gusty this
afternoon with gusts up to 30 kts in the Owens Valley and in
Esmeralda/central Nye/Lincoln counties into this evening.

Spotter information statement...spotter activation is not expected
at this time. However...spotters are encouraged to report any
significant weather conditions according to Standard operating
procedures.
&&

$$

Update...Morgan
short term/aviation...Harrison
long term...outler

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