Area Forecast Discussion
Issued by NWS Tucson, AZ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS65 KTWC 170935

Area Forecast Discussion
National Weather Service Tucson AZ
235 AM MST Thu Aug 17 2017

.SYNOPSIS...Dry westerly flow will shut down thunderstorm chances
into Friday. A moisture increase from the south will gradually
bring isolated to scattered thunderstorms back to the region this
weekend and especially early next week. Temperatures will hover
within a few degrees of normal.


.DISCUSSION...A moderate westerly flow continues with well below
average moisture for mid August. Even international border areas
were showing dew points in the 40s yesterday. Precipitable water
values are ranging from .6 to .8 inches across the area, with
below average values around 1 to 1.3 inches even in southern
Sonora. Southwest Chihuahua and especially Sinaloa were pretty
active yesterday, with the monsoon pushed back deeper into Mexico.

It`s too early to call it quits, and that trend will reverse over
the next 72 hours as northern portions of Mexico get active
again. The complex in northern Sinaloa will help push deeper
moisture through Sonora, staging in southern Sonora and western
Chihuahua tomorrow and then northern portions of the those states
Friday. We`ll be picking up a southerly component to our flow as
this happens, with weak troughiness to our northwest and some
reconsolidation of the ridge to our east. By this weekend, all of
these trends will have pushed deeper moisture back into our corner
of the state along with New Mexico. After the ramp-up over the
weekend, we should be in good shape for storms the first half of
next week.


.AVIATION...Valid thru 18/12Z.
Some debris cirrus level clouds will skirt far SE AZ, impacting KDUG
terminal site, this morning. Otherwise clear thru pd with only a few
aftn cumulus clouds near the mtns. Normal diurnal wind trends less
than 12 kts. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry westerly flow aloft will continue into Friday.
Isolated to scattered showers and thunderstorms will then return
this weekend into early next week. 20-foot winds will generally be
terrain driven at less than 15 mph apart from any thunderstorms






Visit us on Facebook...Twitter...YouTube...and at is the U.S. government's official web portal to all federal, state and local government web resources and services.