Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Phoenix Arizona
240 am MST Monday Mar 17 2014
dry westerly flow aloft is forecast through the coming
weekend...however the tail end of a dry cold front will move across
northern Arizona tonight and Tuesday...resulting in breezy
conditions. Above normal temperatures and clear to mostly clear
skies are forecast across the region for this week.
current situation across the region is that of strong ridging...a
warm air mass and virtually clear skies. The center of the strong
subtropical ridge near 31n/123w will start to shift southward and
weaken over the next day or so. A ridge axis now extending into
northern Arizona will quickly shift southward into northern Mexico
by noon today while a fast moving shortwave trough just coming
ashore in the Pacific northwest dives southeastward flattening the
ridge across the Desert Southwest. Even though the trough energy
will completely miss US to the north...it will lower 500mb heights
from around 582dm to 566-570dm by early Tuesday.
Temperatures today will still end up being very warm even though
heights are in the process of falling. Very little moisture is seen
throughout the entire column...so sunny skies are expected to help
highs peak out in the middle to upper 80s across the lower deserts. A
developing Lee of The Rockies low will allow for a strengthening
pressure gradient by this afternoon across our region which will
result in overall breezy west to southwesterly winds this afternoon.
In general...most places will see periodic gusts in the 20-25 miles per hour
range...but stronger winds across southeast California should result
in some gusts of around 30 miles per hour. Not expecting any widespread blowing
dust with these wind speeds...but can/T rule out at least some very
localized minor visibility restrictions.
From Tuesday on through the rest of the week the synoptic pattern
shifts to broad troughing and west northwesterly upper level flow.
Winds will still be somewhat of a factor on Tuesday...but just
across the lower Colorado River valley with northerly winds gusting
25-30 miles per hour in the afternoon. This will likely result in elevated fire
danger concerns for Tuesday afternoon. Temperatures will take a dip
on Tuesday with the lower heights...but most Lower Desert locations
will still manage to reach into the lower 80s. Very similar
temperatures are forecast from Wednesday on through the coming
weekend...but we should see a couple degree increase on
Thursday...lasting through Sunday. No chances for rain are seen in
the next 7 days with very little moisture to even bring periodic
south-central Arizona including kphx...kiwa...and ksdl...and
southeast California and southwest Arizona including kipl and kblh...
Clear skies will prevail through Monday evening across the region.
Light winds with typical directional trends can be expected through
Monday morning...however an increasing pressure gradient will lead
to more prevailing gustiness Monday afternoon. With fair confidence
have introduced west/SW gusts in the 18-25kt range...though specific
onset timing carries somewhat lower forecast confidence.
Aviation discussion not updated for amended tafs.
Tuesday through Saturday...
above normal temperatures and clear skies will be the norm through
the period as high pressure builds back into the Desert Southwest.
Breezy conditions are expected on Tuesday as a trough passes by to
the east of the region. Winds are expected to remain below advisory
criteria at this time. Very dry conditions will persist through the
week with no mention of precipitation chances during this time
period. Elevated fire danger concerns with low humidities and breezy
conditions will be present.
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