Area forecast discussion 
National Weather Service Tucson Arizona 
940 am MST sun Jun 26 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 next Saturday. 


&& 


Discussion...still plenty of debris cloud this morning with 
embedded light showers. This is going to slow the heating a bit 
with initial clearing underway in portions of Cochise and Santa 
Cruz counties. The 12z ktwc sounding still has plenty of moisture 
at 1.4 inches precipitable water. The mid level easterly flow has 
already increased substantially accompanied by an increase in 
shear that should help to organize outflow activity this 
afternoon. The direction favors strong outflow off the Mogollon 
Rim through Graham County. 


Latest hrrr trends push 2 strong outflows westward, including the 
rim shot and a second outflow from activity in Cochise County 
pushing west and northwestward. The 12z uofa WRF-NAM paints a 
similar scenario with the outflow from the Cochise County activity 
pushing through the Tucson Metro area around mid to late 
afternoon. Minor adjustments to increase activity in the east 
central mountains and subsequent outflow westward, otherwise we 
have solid forecast trends. Please see the previous discussion 
below for additional details. 


&& 


Aviation...valid through 27/18z. 
Isolated to scattered -tsra/-shra. The best timing for thunderstorms and rain at 
the ktus/kols/kdug terminals is mostly from 20z this afternoon 
until 27/02z this evening. Brief wind gusts to near 40 kts and 
MVFR conditions due to reduced visibilities will be possible with 
the stronger thunderstorms and rain. Isolated -shra/-tsra will be possible area-wide 
late tonight into early Monday morning. Otherwise, cloud decks 
generally ranging from 10k- 15k ft msl, and surface wind terrain 
driven mainly less than 12 kts. Aviation discussion not updated 
for taf amendments. 


&& 


Fire weather...expect isolated to scattered showers and 
thunderstorms this afternoon and evening. Greater coverage of 
showers and thunderstorms should then occur Monday through next 
Saturday. 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 into Monday as well as 
Thursday through Saturday will be terrain driven at less than 15 
mph. 20-foot winds Tuesday and Wednesday will generally be from 
the east at 5-15 mph with gusts of 15-20 mph. The strongest speeds 
Tuesday and Wednesday should prevail from shortly after sunrise 
into the early afternoon hours. 


&& 


Previous discussion...the hi-res models suggest a scenario late 
tonight similar to that presently occurring across the area. In 
other words, a fairly widespread convective debris cloud cover 
with patches of sprinkles or light rain. 


26/00z GFS/ECMWF/CMC remained fairly similar regarding the synoptic 
scale pattern regime over the southwestern states starting Monday 
and continuing into early next weekend. Strong high pressure aloft 
Monday is progged to become centered over southern Utah. The GFS/ 
European model (ecmwf) depict an inverted trough to move into southwestern Arizona from 
the northern Gulf of California Monday. 


Quick glance at the u/a WRF-NAM suggests that showers/tstms Monday 
afternoon would only be confined to the White Mountains and near the 
international border adjacent Santa Cruz/southern Pima County. Thus, 
there is the potential that Monday may be a "down day" perhaps due 
to subsidence on the eastern periphery of the aforementioned 
inverted trough. Forecast confidence in this particular detail is 
somewhat low, however. Thus, for this forecast package, have 
continued with scattered showers/tstms mainly from Tucson 
eastward/southward. 


Thereafter, not much daily variation in shower/tstm coverage is 
anticipated Tuesday into next Saturday. The deterministic GFS/ECMWF/ 
CMC were similar with maintaining fairly ample moisture across this 
forecast area. These solutions were similar with the continuation of 
a light Ely/sely mid-level flow regime thru about Wednesday. The mid- 
level flow regime is then progged to become more wly/swly especially 
from Tucson westward starting Thursday and continuing into next 
Saturday. This subtle change may be sufficient for at least a slight 
downward trend in shower/tstm coverage, especially across western 
sections. Again, forecast confidence is fairly low at this time in 
stating that a definitive downward precip trend anywhere in the area 
is in the offing late this week. 


High temps for the Tucson Metro area and locales west-to-northwest 
of Tucson will be near normal during much of this forecast period. 
However, daytime temps for locales east-to-south of Tucson, such as 
Safford, Douglas and Nogales will average a few degs below normal 
this week. 


&& 


Twc watches/warnings/advisories... 
none. 


&& 


$$ 


Meyer/Francis 


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