798
FXUS66 KPDT 211654 CCA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
953 AM PDT Sun Jul 21 2024

Updated aviation discussion

.SHORT TERM...Today through Tuesday...A few different things set to
occur over the next couple of days. First, the upper level ridge of
high pressure will continue to exert itself over most of the
forecast area today as an upper level trough slowly approaches from
the northwest. Cooler air from west of the Cascades will begin
pushing over the Cascades today in the form of a marine push
bringing some relief from the very hot temperatures but also some
breezy winds of 10-20 mph in the afternoon. However, the rest of the
forecast area will continue to bake under one last day of very hot
temperatures and some possible record highs. Also currently watching
the weak shortwave being pulled north triggering some convection
over western Oregon. As it continues moving up the coast it could
aid in the development of some convection over southern and central
Oregon this afternoon with 15-25% chance of thunderstorms. Some of
this could lift north along the east slopes of the Cascades in the
late afternoon and evening as the shortwave continues moving north.
Models continue tracking some of the decaying convection across the
forecast overnight but with loss of forcing from the departing
shortwave feel that some sprinkles might be all that is let.

On Monday the upper level ridge will be pushed eastward as the upper
level trough begins moving into the Pacific Northwest. This will re-
enforce the marine push by bringing cooler moist air into the region
further cooling temperatures across most of the forecast area. This
will produce some 15-25 mph winds along the east slopes of the
Cascades and push out into the Columbia Basin. One exception will be
the eastern mountains which will still be more under the influence
of the departing upper level ridge. The continued hot and unstable
conditions over the eastern mountains could trigger a few
thunderstorms (15% chance) in the afternoon through evening.

By Tuesday the upper level trough pushing into the pacific Northwest
will be the dominate weather feature impacting the forecast area.
This will bring high temperatures around the Columbia Basin back
down into the lower to mid 90s.

.LONG TERM...Wednesday through Sunday...

Through next week, an upper-level trough slowly moves across the
region with cool near normal temperatures and breezy winds, bringing
SW wind aloft. Thunderstorms and mountain showers could occur late
Wednesday through early night, mainly across the John Day Basin and
eastern mountains. But, chances are low (<15%) given the marginal
instability and limited moisture advection from dry conditions.
Temperatures will remain in the 80s and 90s across the forecast area
for next week, but with portions of the Northwest Blues in the 70s
Friday through the weekend.

Locally breezy conditions (15-25 mph) occurs through Thursday with
occasional wind gusts between 20-30 mph each day through evening
along the Cascade Gaps and east slopes of the Cascades. This could
pose a threat to any ongoing fires as well. Probability for wind
gusts exceeding to 40 mph for Kittitas valley is at 30-60%. Winds
will decrease to light starting Friday and over the weekend.
Feaster/97

&&

.AVIATION...18Z TAFs...VFR conditions will prevail through the
period. However, isolated/scattered thunderstorms are expected to
develop this afternoon over central Oregon and move northeast before
dissipating this evening. KRDM and KBDN may see a storm nearby.
Gusty winds can be expected in the vicinity of these storms. Winds
will be 5-15 kts with higher afternoon/evening gusts, except KDLS 15-
25 kts and gusty. Winds will decrease overnight. Earle/81

&&

.FIRE WEATHER...Very hot, dry and unstable conditions will remain
over the forecast area today. A weak shortwave moving up the coast
could trigger some thunderstorms over central Oregon this afternoon
and then spread north along the east slopes of the Cascades into
Washington by evening. Red Flag Warnings are in effect through this
evening over portions of central Oregon for the hot and unstable
conditions as well as the lightning potential.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT 103  63  96  56 /   0  10  10   0
ALW 108  67 100  62 /   0  10  10   0
PSC 107  68 100  62 /   0  10   0   0
YKM 103  68  99  58 /  10  10   0   0
HRI 106  67  98  60 /   0  10   0   0
ELN 104  69  95  58 /   0  10   0   0
RDM  97  57  93  49 /  20  20  10   0
LGD 105  63 100  57 /   0  10  20  20
GCD 105  64 102  58 /  10  20  20  20
DLS  97  64  89  57 /  10  20   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 10 PM PDT Monday for ORZ041-044-049-
     050-502-503-505-507-508.

     Red Flag Warning until 11 PM PDT this evening for ORZ642-644.

     Heat Advisory until 8 PM PDT Monday for ORZ506-510-511.

     Red Flag Warning from noon today to 10 PM PDT this evening for
     ORZ611-640.

WA...Excessive Heat Warning until 10 PM PDT Monday for WAZ024-026>030-
     521.

     Heat Advisory until 8 PM PDT Monday for WAZ523.

&&

$$

SHORT TERM...91
LONG TERM....97
AVIATION...81