Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 252202
Area Forecast Discussion
National Weather Service Tucson AZ
302 PM MST SAT JUN 25 2016
.SYNOPSIS...We now have enough moisture for isolated to scattered
showers and thunderstorms this weekend. A more favorable flow
regime will then provide increased coverage of showers and
thunderstorms Monday through Friday.
.DISCUSSION...We`re under a broad regime of mid level high
pressure, with anchors just off the northern coast of Baja, and
just east of Texas. In between there is a very nice inverted
trough pushing through southern and western Texas. This feature is
generating organized convection through portions of Texas and New
Mexico, however our flow regime is much weaker. We do have plenty
of moisture to work with, with precipitable water values between
1.2 and 1.4 inches. Our afternoon is going pretty much as expected
to this point, with increasing convection near a weak moisture
convergence area from central Pima county southward through Sonora
and Santa Cruz county. The southern half of Cochise county is
also getting in on the action with a bit more sun today than other
areas. Slow movement to the west and northwest will continue
through the mid evening hours and should push through eastern Pima
and into Pinal county later this afternoon and early evening.
For Sunday, some secondary consolidation in the broad scale mean
ridge position should tamp down convection with most favored
locations being the central mountains and international border
areas. Starting the day with what should still be a relatively
weaker flow will make storms initially reluctant to push away from
the mountains Sunday afternoon. However the UofA WRF-GFS is
hinting at a couple of nice strong outflows pushing west and
northwest late Sunday afternoon and early Sunday evening, filling
in valley locations and probably generating dust north of Tucson.
After that, as high pressure strengthens north of the area, the
first half of the new week should see a better flow regime
(albeit still on the weak side) for reinforcing deep moisture
and importing one or two weaknesses in the flow. This should
serve to anchor the entire week for seasonal convection.
.AVIATION...VALID THRU 27/00Z.
Isolated to scattered -TSRA/-SHRA this afternoon into Sunday
morning, and then again Sunday afternoon. Cloud decks ranging
from 10k- 15k ft msl. Gusty outflows possible with storms,
otherwise surface wind will generally be less than 10 kts into
Sunday. However, surface wind this afternoon vicinity KSAD will
be wly/nwly at 12-16 kts with gusts to near 20 kts. Aviation
discussion not updated for TAF amendments.
.FIRE WEATHER...Expect isolated to scattered showers and
thunderstorms this weekend. Greater coverage of showers and
thunderstorms should then occur Monday through next Friday.
Otherwise, daytime minimum relative humidity values will generally
range from the mid teens to around 30 percent with fair to good
nighttime recovery. 20-foot winds this weekend as well as
Wednesday through Friday will be terrain driven at less than 15
mph. 20-foot winds Monday and Tuesday will generally be from the
east at 5-15 mph with gusts of 15-20 mph. The strongest speeds
Monday and Tuesday should prevail from shortly after sunrise into
the early afternoon hours.
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson