Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tucson Arizona
220 PM MST Wednesday Nov 25 2015
Synopsis...cooler temperatures for the Thanksgiving four day
Holiday period. There is a slight chance of showers tonight into
early for areas southeast of Tucson. Dry conditions with more
seasonable temperatures will then prevail Sunday into Tuesday.
Discussion...mostly cloudy conditions prevailed across Southeast Arizona
this afternoon per satellite imagery and surface based observations.
Water vapor imagery this afternoon showed upper level low over far
western Nevada near Reno moving slowly to the east-southeast. Precipitable water values
over the area...per several sources...are the 0.50"-0.75" range with
1" values just S of the intnl border. Breezy to locally windy
conditions also this afternoon but cloud cover has inhibited full
mixing of winds down to the surface.
For tonight...as the upper low meanders over western Nevada tonight a weak
disturbance approaching the northern Baja California coast will move over the area
bringing the needed dynamics for a few light showers especially S
and east of a Duncan to Sierra Vista line with the best chances over
far southeast Cochise County. Quantitative precipitation forecast values will generally be less than a
tenth of an inch.
Thanksgiving day...the official climate site in Tucson has not
recorded any precipitation on the previous 15 turkeys days...dating
back to 1894...that fell on November 26th. At this time it looks
like that streak will continue with the best chances of measurable
rain being across Cochise County...especially southeast parts. The above
mentioned low in Nevada will move into western Utah during the afternoon
hours. Cooler with highs 3-10 degrees cooler than today.
Upper level low will continue to meander over eastern Nevada/western Utah through
the weekend before lifting NE early next week. Kept low end probability of precipitation
Aviation...valid through 27/00z.
Scattered-broken clouds at 5-10k feet above ground level will continue through the forecast
period especially from ktus eastward. Southwesterly surface wind at 12-15 kts
with a few gusts to 25 kts possible through early this evening before
relaxing to less than 12 kts except for the higher terrain. Isolated
-shra are possible near the kdug terminal after 26/07z. Elevated SW
winds of 12 to 15 kts will occur again tomorrow afternoon especially
near the kols/kalk/kdug terminals. Aviation discussion not updated
for taf amendments.
Fire weather...dry conditions today will give way to a slight
chance of showers tonight through Saturday afternoon mainly across
fire weather zones 152 and 153. Then...dry conditions will return
Sunday into early next week. Southwesterly breezes of 15-20 miles per hour
during the afternoon and early evening hours will continue through
Friday. Saturday into next week 20-feet winds will generally be light
and terrain driven.
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