Freeze Warning 4, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
157 PM MST Mon Apr 3 2023

.SYNOPSIS...Cooler air will move into the area tonight and
Tuesday. High temperatures will be significantly lower than those
that occurred Monday with a very chilly Tuesday night. A
significant warmup will occur late in the week into the weekend.

&&

.DISCUSSION...Southwest winds have increased as expected this
afternoon and will continue to be gusty well into the evening. On
Tuesday, winds will be out of the northwest with much cooler and
drier air moving in. Graham and Greenlee counties will see winds
near advisory levels but perhaps more impactful will be the low
humidities and strong winds which will once again prompt a Red
Flag Warning for those areas along with Eastern Cochise County.
See Fire Weather Section for more details.

The drier air will be marked by dew points dropping into the
single digits in the valleys and below zero over the mountains.
This very dry air combined with the cold air mass and decreasing
winds Tuesday night will allow temperatures to plummet. A Freeze
Watch has been posted for portions of Pinal and Pima counties with
low temperatures generally between 29 and 34 degrees. All locales in
these counties may not quite reach the freezing mark, and for
those that do, the duration of subfreezing temperatures may only
be for an hour or two. However, since this is unusual for April
in these areas, decided to hoist the watch for greater awareness.
It will be colder farther east, but a freeze at this time of year
is not all that uncommon even though some locales may set records.
See Climate Section for more details about the cold temperatures.

After the chilly morning Wednesday, a warmup will begin with above
normal high temps by this weekend. The upper ridging bringing the
warmer readings will also provide a respite from windy conditions
other than a bit of afternoon gustiness.

&&

.AVIATION...Valid through 05/00Z.
SKC through the period but SCT clouds AOA 20k ft MSL N of KCGZ-SAD
after 04/06Z. SFC winds SW 20-30 kts with gusts 35-45 kts
diminishing through 04/06Z but becoming NW 8-18kts thru 04/12Z.
NW winds 20-25kts E of KSAD-KALK after 04/19Z. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...A Red Flag Warning continues into the evening SE
Fire Weather Zone 150 along with most of Zones 151 and 152 where
the dead moisture fuel load is heaviest. Very low humidity levels
below 10 percent will occur again Tuesday in the valleys despite
being much cooler and 20-foot winds will increase to greater than
20 mph in Zone 152. Therefore a Red Flag Warning has been issued
for that area Tuesday. After a cold Wednesday morning, a
significant warming trend will begin with well above normal
temperatures expected by Sunday. Winds should remain below
critical thresholds Wednesday through Sunday.

&&

.CLIMATE...The air mass behind the system passing through the area
on Tuesday will be rather cold for April on Wednesday morning.
For Tucson, the current forecast low Wednesday of 32 degrees,
although not a daily record, would be the first April low of 32
degrees or colder at the official location since 1945. For
Willcox, the current forecast low of 21 degrees would not only be
a daily record (24 degrees in 1937) but would be the coldest
April low since 1971. Significant warming to close the week with
the first 90 degrees of the year possible on Easter Sunday. Latest
probabilities has a 35% chance of 90 degrees at Tucson airport.

DATE                         Apr 05
                          FCST RCD/YR
TUCSON INTL AIRPORT        32  28/1901
AJO                        38  35/1999
ORGAN PIPE CACTUS          38  31/1983
PICACHO PEAK               33  37/1999
SAFFORD AG STATION         28  29/1999
SIERRA VISTA FD            30  28/1999
TOMBSTONE                  24  29/1999
WILLCOX 				   20  24/1937
BISBEE                     29  22/1999
DOUGLAS                    25  21/1999

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM MST this evening for AZZ151-152 and
southeast portions of AZZ150.

Wind Advisory until 11 PM MST this evening for AZZ501>515.

Red Flag Warning from 11 AM to 7 PM MST Tuesday for AZZ152.

Freeze Watch from late Tuesday night through Wednesday morning
for AZZ502-504>506.

&&

KD

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