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Area forecast discussion...update 
National Weather Service Pendleton or
1040 am PDT Tuesday Jul 7 2015

Updated aviation discussion

Short term...morning update...upper flow over the region remains
westerly this morning. This flow will slowly shift to more
northwesterly this afternoon and evening due to a wave that will
move out of British Columbia. Will see an increase in drier middle and
upper level air over northeast Oregon today. This drying will work
into central Oregon this evening. As a result, expect the shower and
thunderstorm threat today to become increasingly suppressed towards
the southern edge of our forecast area. Best chances of
thunderstorms will run across southern portions of Deschutes, Crook
and Grant counties late afternoon and early evening. May also see a
few showers/storms over the higher terrain of Kittitas County in
central Washington due to the b.C. Wave. Main focus of the morning
updates was to adjust shower/storm coverage and locations. Also a
few tweaks to sky cover, high temperatures and winds were made. 90

Long term...previous discussion...upper low off the California coast will
lift northeastward across the region on Friday and Saturday while another low
becomes established off the Pacific northwest coast. This second low will
open up into a shortwave trough and gradually move inland Monday and
Tuesday of next week. This scenario will result in unsettled weather
through the forecast period with a chance for showers and
thunderstorms especially central and northeast mountains. Best
chances for rain will be on Friday and Saturday afternoon and
evening with local probability of precipitation over the eastern mountains. Thunderstorm
coverage could be scattered during this time period. Deep layer flow
will be weak so there could be some heavier rain with the slow
moving storms. Nevertheless given the dry fuels fire weather will
becoming an increasing concern late in the week. Temperatures will
be cooler with increased cloud cover helping to suppress afternoon
high temperatures. Highs will be mainly 85-95 in the lower
elevations and 70-80 in the mountains. It will be breezy in the
Columbia River gorge and Kittitas Valley during the afternoons and
evenings but it does not look like winds will be strong enough for
wind advisories. 78


Aviation...18z tafs...VFR conditions will prevail through the
forecast period. Included vcsh from 07/22z to 08/03-04z at krdm with
thunderstorms in the vicinity during this same time period at kbdn as the best convection is
forecast to develop across southern Deschutes County. With this said
certainly cannot completely rule out a thunderstorm at or in vicinity of krdm
later this afternoon and will amend if the current thinking changes.
Otherwise just a few middle and high clouds will be around
today...tonight and into Wednesday. Winds will be mostly west-northwest at 5-
15 knots this afternoon and early evening otherwise terrain driven
through the forecast period. The only exception to this is at kdls
where winds will be northwest 15-25kt through 08/06z this evening. 77


Fire flag warning in effect for fire weather zones
or610...611...640...and 642 for thunderstorms with abundant
lightning through this evening. Scattered thunderstorms are expected
across or611 and for the southern portions of or 610...640...and
642. Gone with lal 4 for the 611 zone as that area looks to see the
most activity. Southern 640 and 642 should see lal 3. Thunderstorms
are expected to increase in coverage and intensity across central
and eastern Oregon late Thursday through next weekend when the low
opens and develops a broad trough west of The Rockies. The good news
is that storms may bring heavy rain...especially late in the week.


Preliminary point temps/pops...
PDT 99 65 97 65 / 0 0 0 0
alw 99 71 97 71 / 0 10 0 0
psc 101 68 101 66 / 0 10 0 0
ykm 98 68 99 68 / 0 0 0 0
hri 101 68 101 66 / 0 0 0 0
eln 98 65 101 65 / 10 10 0 0
rdm 94 55 92 58 / 20 10 10 10
lgd 93 54 90 55 / 10 10 10 10
gcd 96 57 96 59 / 20 10 20 20
dls 98 69 99 70 / 0 0 0 0


PDT watches/warnings/advisories... flag warning until 9 PM PDT this evening for orz610-611-640-


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