Scientific Forecaster Discussion
fxus65 ktwc 240404
Area forecast discussion
National Weather Service Tucson Arizona
904 PM MST Mon Oct 23 2017
Synopsis...the heat continues with near record high temperatures
west of Tucson on Tuesday. Temperatures then gradually decrease the
rest of the week, but remain above average for late October. Dry
conditions also prevail, with a period of strong easterly winds on
Tuesday into early Wednesday.
Discussion...strong upper-level ridging provided a hot and clear
day across southeastern Arizona this afternoon. Record high
temperatures were recorded in both Tucson (96f) and Douglas (91f).
Temps have since decreased quickly in this very dry regime, as
evident in the 24/00z sounding that showed 0.26" of precipitable
water. Nothing of great significance is expected through the
remainder of tonight--clear skies and light terrain driven winds.
The surface gradient tightens significantly on Tuesday producing
strong east to southeasterly flow. Breezes pick up shortly before
sunrise along the New Mexico border, expanding westward across the
forecast area during the morning. Conditions may approach Wind
Advisory criteria in some locales for a brief period of time,
especially in the Tucson Metro area, but will not be widespread
enough to justify any further actions.
A few slight tweaks were made to the forecast this evening based on
the latest guidance. High temperatures were dropped 2-5 degrees from
Tucson east and winds were brought up a couple knots in the Tucson
Metro area. For details on the remainder of the week, please see the
previous discussion below.
Aviation...valid thru 25/06z.
Clear skies into Tuesday evening. Surface wind variable in direction
mainly less than 10 kts through the night, increasing Ely/sely 10-25
kts with gusts to 35 kts by around 24/15z, continuing into Tuesday
evening. Aviation discussion not updated for taf amendments.
Fire weather...dry conditions continue into early next week.
20-foot sustained winds Tuesday morning into Wednesday morning east
to southeast 10-25 mph with gusts to near 35 mph. A few locations in
fire weather zone 151 may briefly reach critical fire weather
thresholds late Tuesday morning and early Tuesday afternoon. The
gusty east winds will decrease Wednesday afternoon. Winds turn west
to northwest Thursday and Friday and become breezy again, especially
for areas east of Tucson.
Previous discussion /227 PM MST/...an unseasonably strong ridge of high
pressure will bring record high temperatures to the area today, with
near record values Tuesday. We're on the eastern flank of the ridge
with a strong trough digging into most of the country downstream.
Dry conditions in the flow around the ridge with precipitable water
between .2 and .3 inches. Surface dew points are down 8 to 10
degrees over the past 24 hours, generally in the teens and 20s.
We'll see gusty easterly winds develop Tuesday as a surface high
builds down the Front Range of The Rockies, but still not much
High pressure will retreat into the eastern Pacific as the trough
deepens through much of the rest of the country. As a result our
temperatures will gradually moderate over the next several days, but
still remain above average. Gusty winds developing Friday as the
ridge tries to nudge back in from the west and a stubborn mean
trough position remains immediately downstream.
No precip until further notice.