Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 010415

Area Forecast Discussion
National Weather Service Tucson AZ
915 PM MST Sun Apr 30 2017

.SYNOPSIS...Strong high pressure aloft over the eastern Pacific will
expand eastward into the desert southwest later this week. Expect
dry conditions through Friday, and high temperatures Wednesday into
Friday will be well above normal. The high temperature at Tucson
Friday should approach 100 degrees. Some increase in moisture may
produce a few showers and thunderstorms east of Tucson next weekend.


.DISCUSSION...Generally northwesterly flow aloft across southeast
Arizona this evening with deep low pressure centered over eastern
Kansas, and strong high pressure aloft centered west of the central
California coast near 33N/133W. The flow regime has resulted in
clear skies at this time, and surface winds were westerly to
northerly at less than 15 mph.

Clear skies and light winds will occur the rest of tonight, with low
temperatures around daybreak Monday to be about 3-10 degrees or so
warmer versus temperatures achieved early this morning. High
temperatures Monday are forecast to be generally 3-8 degrees warmer
versus temperatures recorded this afternoon. A gradual daily warming
trend will then continue Tuesday into Friday, and the first official
occurrence of 100 degrees may occur Friday at the Tucson
International Airport.

At any rate, there are no updates necessary at this time. Please
refer to the additional sections for further detail.


.AVIATION...Valid through 02/06Z.
Clear skies will prevail into Monday evening. Surface wind will be
variable in direction mainly less than 12 kts into Monday morning,
then surface wind Monday afternoon and evening will be wly/nwly 8-18
kts with gusts to near 25 kts. Aviation discussion not updated for
TAF amendments.


.FIRE WEATHER...Dry conditions will prevail through Friday. Daytime
minimum relative humidity will be in the single digits at lower
elevations and the teens in the mountains. Generally light terrain
driven wind will occur through Wednesday, although afternoon west to
northwest gusts will occur due to strong daytime heating. A somewhat
tight surface pressure gradient Thursday into Friday should produce
some gusty east to southeast winds at times. Thereafter, increased
moisture will lead to a slight chance of showers and perhaps
thunderstorms next weekend.


.PREV DISCUSSION /230 PM MST/...Clear skies continue this afternoon
for much of Arizona as a rather large and mature low pressure system
is spinning its way across the Central Plains, bringing severe
weather to parts of the southeast. We`ll generally remain under
northwest flow aloft into Wednesday as strong ridging gradually
builds in from the west. The result will be mostly clear skies with
a few passing cirrus, a warming trend and a much-needed break in the
winds. By late week, the ridge axis passes overhead with heights and
thicknesses supporting the potentially-first 100 degree day of 2017
at KTUS on Friday. Next weekend, we`ll watch as a deep trough tries
to dive southward along the coastline and cutoff to our west under
the synoptic ridge. This would signal another round of gusty winds
along with a few showers and perhaps thunderstorms depending on the
track. With such low confidence at this time, have kept PoPs fairly
low with just slight chance values across the eastern/northeastern
mountains next Saturday and Sunday.






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