Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 180402

Area Forecast Discussion
National Weather Service Tucson AZ
902 PM MST Tue Apr 17 2018

.SYNOPSIS...High pressure will bring warmer temperatures
Wednesday. Stronger winds will return Thursday into Friday as a
storm system moves north of the area. Cooler temperatures and a
few showers possible near the mountains northeast of Tucson
Friday. Warmer next weekend.


.DISCUSSION...No surprises this evening with the trough now east
of the area and high pressure building in from the west. Clear
skies and dry conditions in a weakening westerly flow. Surface dew
points are in the teens, and the 00z KTWC sounding came in with
1/4 of an inch precipitable water. Surface winds are diminishing
as expected as the gradient relaxes. Overnight lows will be a
few degrees cooler than average, but nothing unusual.

Next up will be another windy system Thursday into Friday with
accompanying fire weather and blowing dust concerns. Our current
forecast handles this pretty well. Please see sections below for
additional details.


AVIATION...Valid through 19/06Z.
Mostly clear. Surface winds diminishing to less than 10 kts
overnight. Normal trends generally less than 12 kts through the
period, with some gustiness in the afternoon. Aviation discussion
not updated for TAF amendments.


.FIRE WEATHER...A Fire Weather Watch is in effect Thursday from
11 am to 8 pm MST for Fire Weather Zones 150, 151, 152, and 153.
The combination of strong and gusty southwest to west winds, low
humidity, and a high to very high fire danger will create critical
fire weather conditions.

Wednesday winds will be weaker with some gusts possible in the
afternoon. Strong winds will return Thursday for all of southeast
Arizona along with minimum relative humidities in the single
digits. Friday will be another gusty day with brief critical fire
weather conditions possible east of Tucson. A slight chance of
rain/snow showers Friday into late Friday night exists across the
White Mountains. Dry conditions with relatively light winds for
April to prevail Saturday morning into next Tuesday.


.PREV DISCUSSION...At 1 pm this afternoon, IR imagery showed
generally clear skies across southeast Arizona, and west winds
were gusting 25-40 mph across much of the Red Flag warning area
in the wake of a departing cold front. RH values were very low in
southeast AZ, mostly below 15 percent and in the single digits in
some locations such as Fort Huachuca and Safford. One of the
lowest RH values was seen in Douglas with a reading of just 4
percent. As such, the Red Flag Warning looks to be performing
well and will remain in effect thru 7 pm.

The state will be in between systems on Wednesday before yet
another windy system passes through Thursday into Friday. This
system will be stronger and track farther south through northern
Arizona. That said, another round of high winds resulting in
critical fire weather conditions and areas of blowing dust can be
anticipated on Thursday. A Fire Weather Watch remains in effect
for Thursday due to the expected dry and windy conditions. The
system will also bring a brief cool down in daytime temperatures.
Dry and warmer weather will return this weekend and into early
next week as high pressure aloft builds into the area from the
west; warmer western deserts will reach or exceed 90 degrees by


Fire Weather Watch from Thursday morning through Thursday
evening for AZZ150>153.




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