Forecast Discussion

Forecast Discussion for TWC NWS Office
000
FXUS65 KTWC 280940
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
240 AM MST Thu Mar 28 2024

.SYNOPSIS...

Expect warmer temperatures today into Saturday before a weather
system brings colder temperatures and widespread precipitation
chances early Sunday into early next week. Rain and accumulating
mountain snow is likely. Winds will increase ahead of this system
on Friday, with windy conditions lasting through the weekend.

&&

.DISCUSSION...

As an upper level ridge crosses the region, temperatures today
through Saturday will be well above what they were just a couple
days ago. Forecast highs today and Friday are in the 70s to lower
80s across the lower elevations, and a tick lower on Saturday. By
Saturday, a deeply anomalous trough (500mb heights near
climatological minimum on NAEFS guidance for this time of year)
will be over the California coastline, while strong southwest
flow will be present over southeastern Arizona. The increased
unidirectional flow aloft will drive breezy to windy conditions at
the surface starting Friday, and lasting through the weekend as
an associated jet streak crosses aloft. Precipitation will arrive
initially along a mid-level frontal push crossing the state early
Sunday through early Monday. This will combine with strong
divergence aloft to drive periods of heavier rain and mountain
snowfall rates along and near the frontal boundary. Additional
precipitation is likely Monday as cold air aloft will bring
diurnal instability and convective activity. The seasonally
impressive upper level support and southwesterly moisture draw will
bring chances for precipitation to all of southeastern Arizona,
with Sunday potentially exceeding the normal monthly
precipitation total for April in under a day as described in the
previous discussion. Accumulating mountain snow above 7000 feet may
need headlines, most likely in the Whites but potentially the
Catalina, Rincon, and Pinaleno mountains as well. Sunday and
especially Monday, high temperatures will be well below normal.
The ECWMF extreme forecast index highlights the highly anomalous
temperature forecast for Monday with values near bottoming out in
southern Arizona, as forecast highs range from 15 to 20 degrees
below normal. Low temperatures Tuesday morning will depend on the
exiting moisture, but still have likely probabilities of near to
below freezing morning lows in historically cooler valleys of
Cochise and Graham counties.

Temperatures should moderate going into the middle of next week
as the trough exits. It`s worth noting that long range models are
in good agreement with lower height anomalies returning by the
end of next week, which is leading to CPC`s 8-14 day outlook
leaning below normal for temperatures and above normal for
precipitation for that period.

&&

.AVIATION...Valid through 29/12Z.

Gradually increasing cloud cover today at 20k feet and above.
Winds may increase to around 10 kts out of the west in some
exposed areas this afternoon, but generally remain light and
terrain driven. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...

Warmer today through Saturday as a ridge builds. Winds will
increase on Friday to around 15 to 25 mph ahead of an approaching
storm system, which may overlap relative humidities of 10 to 15
percent in the lower elevations. Winds should become a bit higher
on Saturday, though moisture will be on the rise. Good chances for
widespread precipitation arrive with a cold front by early Sunday,
lasting through Monday and potentially Tuesday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

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NWS TWC Office Area Forecast Discussion