Area forecast discussion
National Weather Service Flagstaff Arizona
1005 am MST Sat may 25 2013
Synopsis...a broad low pressure system will remain over the Pacific
northwest through Memorial Day. This will produce periods of gusty
southwest winds and dry conditions across northern Arizona. A low
pressure system is forecast to affect the southwest by Tuesday and
Wednesday of next week...with cooler temperatures and a chance of
showers or thunderstorms.
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Discussion...the dry...warm...and breezy weather pattern will
continue today. Overall...weather conditions will be very similar to
yesterday. Forecast trends are on track with no morning updates
needed.
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Previous discussion (330 am mst)...a persistent closed low pressure
system residing over the northwest U.S. Will continue to bring dry
conditions and breezy southwest winds to northern Arizona through
Memorial Day. High temperatures will be within a degree or two of
normal.
Tuesday into Wednesday...the northwest U.S. Low digs a trough of low
pressure southward into the southwest states. This weather
disturbance will bring an increase in the southwest flow...below
normal high temperatures...and an increase in moisture and
instability which will lead to isolated to widely scattered showers
and thunderstorms late Tuesday into Wednesday. The European model (ecmwf) has been
consistently deeper with moving a low pressure trough through
Arizona...with colder temperatures windy conditions and greater
chances for precipitation. The GFS has been trending closer to the
European model (ecmwf) solutions. For now the forecast for Tuesday into Wednesday
cover a blend between both the GFS and the European model (ecmwf).
Thursday and Friday...the closed low is forecast to move east over
portions of the Great Basin and Wyoming. This pattern will continue
to bring a southwest to westerly flow with breezy to windy
conditions in the afternoon. Relative humidity values will be falling into the
single digits to lower teens by Friday. The GFS and European model (ecmwf) are very
different by next Friday...the GFS has a building ridge where the
European model (ecmwf) has the strong closed low over the upper High Plains states.
The GFS solution would bring lighter winds and warmer
temperatures...meanwhile the European model (ecmwf) would bring much cooler
conditions on northwest flow.
&&
Aviation...for the 18z package...expect VFR conditions with light
cirrus cover 24 hour period. Expect SW surface winds at 15-30kts through
02z Sunday. Aviation discussion not updated for amendments.
&&
Fire weather...a broad low pressure system will remain anchored
over the Pacific northwest...bringing more breezy and dry conditions
to the region through Sunday. Wind speeds are expected to approach
but not exceed critical fire weather thresholds for our fire zones.
However...a few of the windier locations may briefly exceed these
critical thresholds.
Monday through Wednesday...on Monday...low pressure system will
remain in place along the West Coast...keeping Arizona in a dry
and breezy weather pattern. By Tuesday...a cold front pushes east
bringing stronger winds and cooler temperatures to Arizona. A good
chance for critical fire weather conditions is expected for fire
zones below 5000 feet elevation...north of the Mogollon Rim.
&&
Fgz watches/warnings/advisories...none.
&&
$$
Public.........MCS/tc
aviation.......Peterson
fire weather...Peterson
For northern Arizona weather information visit
weather.Gov/Flagstaff
