Frogville´s Weather Service

Updated:  20-May-2025 4:35pm 
  Clear Temperature: 93.3°F   -1.7°F/hr Humidity: 6% Dew Point: 16.5°F Wind: SSE  0.4 mph Gust: 0.0 mph Barometer: 29.733 inHg  Steady Rain Today: 0.00 in UV Index: 0.0  None

869
FXUS65 KTWC 202000
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
100 PM MST Tue May 20 2025

.SYNOPSIS...High pressure will build into the region this week, with
warming temperatures through Thursday as highs top out at 7 to 10
degrees above normal late this week. Light winds are expected into
Wednesday, with breezy afternoon winds Thursday through Saturday.

&&

.DISCUSSION...High pressure aloft centered over the eastern Pacific
Ocean will shift southeastward to off the Baja coast by Thursday. A
series of systems will move across the northern tier of states
Friday through the weekend, shifting the ridge axis eastward into
the central United States. Early next week, the ridge rebuilds
across the western U.S. and becomes highly amplified through the
Intermountain West into central Canada. Some baggy troughiness
develops along the west coast by the middle of next week as the
ridge shifts eastward to along the front range.

High temperatures warm through Thursday as high pressure moves
toward the region and heights rise. There will be 4-6 degrees of
warming today (versus yesterday) and again Wednesday, with an
additional 2-3 degrees of warming Thursday. These temperatures will
result in minor HeatRisk across most of southeast Arizona, with some
pockets of Moderate HeatRisk Thursday, especially across Pima County
and in the upper Gila River Valley. High temperatures Thursday will
be 7-10 degrees above normal, with lower 100s from Tucson westward
and in the upper Gila River valley around Safford and 90s across the
eastern valleys.

As the ridge axis shifts eastward this weekend and heights lower
slightly, high temperatures moderate a few degrees but will still be
2-4 degrees above normal. Readings will top out in the mid to upper
90s for the western deserts (Tucson westward) and in the upper 80s
to lower 90s for the eastern valleys. Afternoon/early evening wind
speeds increase Thursday through Saturday, with southwest to west
winds of 15-20 mph and gusts to around 30 mph, especially east of
Tucson. Friday appears to be the breeziest day at this time.

The ridge rebuilds over the western United States early next week,
with highs warming back up a degree or two and wind speeds decrease.
In the late Tuesday through Wednesday time frame of next week, the
ridge axis shifts just east of the area as baggy troughiness develops
along the west coast. This combination will shift our flow to a
south-southeast direction and may allow some mid level moisture to
work into eastern portions of southeast Arizona from the east. This
could lead to isolated high based convection over the higher terrain
and NBM probabilities are currently at 10% for Mount Graham, 15% for
the Chiricahua Mountains and 20% in the White Mountains. Confidence
in this scenario is low given the moisture must work its way
westward over the Continental Divide and the short duration of the
south-southeast flow as winds shift back around to a westerly
component on Thursday. However, definitely something to keep an eye
on going forward.

&&

.AVIATION...Valid through 22/00Z.
Clear skies/SKC conditions thru the forecast period. SFC wind 12 kts
or less thru the valid period. SFC wind favoring a WLY/NWLY direction
this afternoon/evening and SWLY/WLY direction Wednesday afternoon,
and winds variable in direction from the late evening through mid
morning hours. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Less wind and a warming trend over the coming days
as a ridge builds over the region. Highs by Thursday will be in the
lower 100s from Tucson westward (and upper Gila River Valley) and in
the 90s in the eastern valleys. Elevated 20-foot winds Thursday
afternoon through Saturday, with the strongest winds on Friday. At
this time, wind speeds stay below critical fire weather thresholds,
but could top out at 15-20 mph and gusts to near 30 mph east of
Tucson on Friday. Single digit min RH values at all elevations over
the next week.

There is the potential for some mid level moisture to move into far
eastern areas by the middle of next week. This may lead to some
afternoon buildups and/or isolated dry lightning strikes Tuesday and
Wednesday of next week. At this time, confidence in this scenario is
low.

&&

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

$$

Zell

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NWS TWC Office Area Forecast Discussion