Area Forecast Discussion
Issued by NWS Pendleton, OR

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

403
FXUS66 KPDT 231709 AAA
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1009 AM PDT Wed Aug 23 2017

Updated Aviation Discussion

.SHORT TERM...Today and tonight...Got a couple of things going on
over the next 24 hours. First, moisture associated with a low
pressure off the California coast has been pulled into the area by
an increasing southwest flow associated with an upper level trough
approaching western Canada. This moisture will produce a few showers
through midday and then the atmosphere will turn more convective
unstable through the afternoon and overnight leading to a chance of
thunderstorms. This will mainly occur from central Oregon to
southeast Washington and could spill out into the eastern portion of
the lower Columbia Basin late this afternoon and evening.

Secondly, the approaching upper level trough will push a dry cold
front across Washington and northern Oregon early Thursday. This
will bring some increasing westerly winds Thursday and begin to push
the convective moisture east and south late overnight and Thursday.
The front will also interact with the convective moisture to help
keep the threat of thunderstorms going over far southeast Washington
and northeast Oregon past midnight and into Thursday morning.

&&

.AVIATION...18Z TAFS...VFR conditions will prevail through the
forecast period. There will be some MVFR VSBYS in HZ and FU at KRDM
and KBDN. Additionally showers and TSTMS will develop this afternoon
and impact KBDN and KRDM...and KALW and KPDT by this evening. This
could create some sub VFR conditions. Otherwise expect mostly mid
and high cloud ceilings. Winds will be 5-15 kt...except locally
strong and gusty near TSTMS. 78

&&

.FIRE WEATHER...For this afternoon and evening, thunderstorm
coverage will increase with the approach/passage of a cold front.
Scattered thunderstorms are expected across Central Oregon in the
afternoon, migrating northeastward across the northeast Oregon
mountains late in the afternoon and evening. The latest short term
models are indicating thunderstorms may linger longer in the Central
Oregon Mountains than originally anticipated this evening. The Red
Flag Warning for FWZ 640 may need to be extended. I will watch
thunderstorm development and make a decision lated this afternoon.

Models continue to slow the progression of the front on Thursday,
Thunderstorms may linger across far eastern Oregon tomorrow. Winds
will increase in behind the front Thursday, with breezy to locally
windy conditions for the Columbia Gorge and Basin. Model trends have
been a bit lighter for winds, and with the maximum winds likely
occurring when RHs are beginning to rise, I will not issue any
watches for Thursday at this time. 76

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  87  62  82  49 /  20  30  10   0
ALW  88  66  86  53 /  20  40  10   0
PSC  91  65  89  48 /  10  20   0   0
YKM  92  60  86  47 /   0  10   0   0
HRI  89  65  87  49 /  20  20   0   0
ELN  89  62  78  49 /   0  10   0   0
RDM  84  52  80  39 /  40  20   0   0
LGD  85  58  81  46 /  20  50  10   0
GCD  84  57  82  48 /  40  60  20  10
DLS  88  65  83  54 /  10   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from noon today to 10 PM PDT this evening for
     ORZ642-644-645.

     Red Flag Warning from 5 PM this afternoon to 10 PM PDT this
     evening for ORZ643.

     Red Flag Warning from noon today to 5 PM PDT this afternoon for
     ORZ611-640.

WA...Red Flag Warning from 5 PM this afternoon to 10 PM PDT this
     evening for WAZ643-645.

&&

$$

91/78/76



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.