Scientific Forecaster Discussion
fxus65 kvef 171746
Area forecast discussion
National Weather Service Las Vegas Nevada
1047 am PDT Wed Jul 17 2019
Synopsis...expect dry and breezy conditions with temperatures
close to seasonal normals through the rest of the week. Increasing
monsoonal moisture is expected late in the weekend or early next
Update...the complex mentioned in this mornings discussion has
pushed out a deep surge of moisture up the Colorado River valley.
Dewpoints have surged to the upper 60s in the last hour at kblh.
This moisture has not been handled well in the hrrr or any other
available guidance. Through the morning and afternoon, surface
dewpoints are expected to decrease as low-level moisture as mixes
through the deepening the pbl; however, given the pace of the surge,
sufficient moisture may work its way into the lower Colorado River
valley and southern Mohave County resulting increased clouds and
possibly a few thunderstorms. Elsewhere, southwesterly/westerly flow
aloft should result in dry conditions as the moisture surge is
sheared eastward. Into central/northern Arizona.
Discussion...302 am PDT Wed Jul 17 2019...through next Tuesday.
Satellite imagery shows a large thunderstorm complex over
northcentral Mexico this morning. Models bring moisture associated
with this feature westward into Sonora Mexico and the central Gulf
of California today. 400 mb streamline analysis shows westerly
component winds hanging tough across our area, keeping the
moisture suppressed to well south and east of our southern County Warning Area
borders. Southwest flow aloft is forecast to weaken over our
region today however surface winds are forecast to be similar to
slightly weaker than yesterday. Temperatures are expected to be a
few degrees cooler this afternoon...back closer to normal. Similar
conditions are expected to continue through the weekend with
seasonal temperatures, dry conditions and gusty afternoon winds.
Early next week, the pattern shifts to more of a monsoonal look
as high pressure expanding and strengthening across the
intermountain range with the center near The Four Corners region.
This will turn the upper level flow to the south/southeast
direction...becoming more favorable for increasing moisture
into parts of our area and increasing chances for shower and
Aviation...for McCarran...southwest winds will continue today
with winds increasing to 15-20 knots and gusts up to 30 knots by
For the rest of southern Nevada, northwest Arizona and southeast
California...southwest winds will increase late this morning
becoming 15-20 knots with gusts to around 30 knots. Gusty
conditions will continue into the early evening before decreasing
Fire weather...dry, southwest flow is expected to continue
through the week. Winds will increase late this morning with
gusts generally 25-35 mph through early evening. The strongest
winds will be focused across mainly Mohave and far southern
Nevada where a red flag warning is in effect through this
evening. Breezy southwest winds and critical relative humidity values will continue
each afternoon through the end of the week with gusts generally
in the 20 to 25 mph range.
Spotter information statement...spotters are encouraged to report
any significant weather or impacts according to Standard operating