Excessive Heat Warning 1, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
1010 AM MST Sun Jun 4 2017

.SYNOPSIS...Hot daytime temperatures and a few afternoon
thunderstorms mainly near the New Mexico and International borders
will prevail this week.

&&

.DISCUSSION...Clear skies prevail at this time except for a few
cumuloform clouds across the White Mountains, Mount Graham, and the
Chiricahua Mountains in eastern Cochise County. Dewpoints at lower
elevations valid 9 am MST ranged from the 30s-mid 40s, and these
temperatures were 2-6 degrees lower versus 24 hours ago. Surface
temperatures valid 9 am MST were 2-4 degrees warmer versus this time
Saturday.

04/12Z KTWC sounding total precip water value of 0.76 inch was
nearly identical to 24 hours ago. The column was somewhat saturated
in the 600-500 mb layer, but remained very dry in the surface-700 mb
layer and above 500 mb. 04/12Z upper air plots depicted a 587 dm
high centered near the White Mountains with a ridge axis extending
northward into the northern Rockies. A weak upper low was centered
over western Oklahoma and a trough axis was near the Pacific
Northwest coast. Light northwesterly flow aloft above 500 mb
prevailed across southeast Arizona earlier this morning.

04/12Z Univ. of AZ WRF-NAM and several HRRR solutions were fairly
similar with the depiction of potential shower/tstm development for
early this afternoon. The White Mountains and Chiricahua Mountains
were favored for this development via both models, but the HRRR also
depicted potential development further west across Mount Graham. The
inherited official forecast appears to trend toward the HRRR
solutions. Any measurable rainfall will be quite light, or mostly
just a few hundredths of an inch or so.

At any rate, the main forecast emphasis for today, as well as for
the upcoming week, is regarding the hot daytime temperatures. Strong
high pressure will remain quasi-stationary through about Wednesday,
then move east of the area by the weekend. This pattern will
translate into well above normal daytime temperatures during the
next several days.

Please refer to the additional sections for further detail.

&&

.AVIATION...Valid thru 05/18Z.
Isolated -TSRA/-SHRA mainly near the New Mexico border this
afternoon. Otherwise, FEW-SCT clouds at 10k-15k ft AGL this
afternoon with SKC at other times. Surface wind variable in
direction mainly less than 12 kts, though afternoon gusts near 20
kts especially in vicinity of KSAD. Aviation discussion not updated
for TAF amendments.

&&

.FIRE WEATHER...A few afternoon thunderstorms may occur mainly near
the New Mexico border this week, with the bulk of thunderstorms
remaining east of the area in New Mexico. Most rainfall amounts will
be quite light. However, brief gusty and erratic winds may occur due
to thunderstorm outflows. Otherwise, dry conditions with 20-foot
winds generally less than 15 mph will prevail, although afternoon
gusts will occur due to strong daytime heating.

&&

.PREV DISCUSSION /306 AM MST/...The main weather story will be the
heat as high pressure aloft continues to strengthen over the region.
Latest models still suggested that enough moisture will linger
across eastern sections of the CWA to support some afternoon and
early evening thunderstorms through the week. High temperatures were
projected to peak around Wednesday and Thursday before the ridge
shifts eastward in response to a storm system entering the west
coast.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

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