Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 021557 CCA
Area Forecast Discussion...CORRECTED
National Weather Service Tucson AZ
856 AM MST Fri Dec 2 2016
.SYNOPSIS...Temperatures will remain below normal through the
upcoming weekend. A storm system will move across the region later
today into Saturday, resulting in a chance of valley rain and
mountain snow. Dry conditions return Sunday and Monday. Another
system will then brush the state on Tuesday of next week which will
result in a slight chance valley rain and mountain snow mainly to
areas east of Tucson.
.DISCUSSION...Water vapor imagery shows a low pressure system over
the northern Rockies with an associated trough axis extending
southwest across Utah and northwest Arizona. Meanwhile, a secondary
low is on the tail end of the trough and can be seen in the general
vicinity of southwest Arizona. IR satellite imagery shows cloudiness
associated with this low covering a small part of southeast
California, northern Mexico and a significant part of western and
central Arizona. These clouds are making their way eastward.
Models indicate that as the low slowly moves southeast into northern
Mexico late today through Saturday, we will see a few showers
develop ahead of the low between Ajo and Tucson and this is
reflected in the inherited POP forecast for this afternoon. Showers
will then increase this evening and into Saturday, with the bulk of
the activity over Cochise county.
As of 15Z (8 AM MST), temperatures across the region ranged from the
mid 30s to the lower 40s, with the Tucson Intl Airport reporting a
temp of 40 degs, after a morning low of 37 degs, which was 4 degs
below normal for this date. These current temp readings seem to be
right on track with the inherited afternoon high temps, so no
changes are planned at this time but will continue to monitor.
See the previous discussion below for details beyond today.
.AVIATION...Valid through 03/18Z.
A cut-off low pressure system developing west of the area today will
bring isolated to scattered showers mainly from Tucson south and
east later this afternoon into Saturday morning. Surface wind less
than 12 kts thru the forecast period. Aviation discussion not
updated for TAF amendments.
.FIRE WEATHER...Another low pressure system will move into the
region today and Saturday, resulting in a chance of valley rain and
mountain snow. This system may also produce some gusty east winds.
Dry conditions are expected behind the system Sunday and Monday.
Another system may impact the region Tuesday of next week.
.PREV DISCUSSION...Southerly flow over most of the area tonight into
early Saturday with scattered showers from Tucson east and south.
Snow levels mostly in the 5500 to 6500 foot level. As the cut-off
low sags southeast into Sonora Mexico shower activity will be
diminishing from northwest to southeast during the day on Saturday.
Upslope easterly flow will bring the best measurable snow to the
eastern slopes of the Chiricahua mountains where 2-5 inches is
possible above 6500 feet by Saturday evening.
Dry northerly flow on Sunday as the closed low moves east across
southern Chihuahua MX.
Next weather system will pass by to our north on Tuesday bringing a
slight chance of snow showers to the eastern mountains. Dry W-NW
flow Wednesday and Thursday.
Highs mostly for the next week will be below normal with cool
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