Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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
307 FXUS66 KPDT 122335 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 440 PM PDT Sun May 12 2024 Updated Aviation Discussion .SHORT TERM...Tonight through Tuesday...Current visible satellite imagery shows scattered cumulus fields once again developing over portions of the eastern mountains and the WA Cascades, with clear skies elsewhere. Looking over at water vapor imagery, the upper ridge that has been over the region the past several days has started to push east into ID, while an upper shortwave trough approaches the PacNW coast. Ahead of the shortwave trough, the cross Cascade pressure gradient has begun to tighten, resulting in breezy winds developing through the Cascade gaps and portions of the Columbia Basin. Tonight through Monday, the shortwave trough currently approaching the region and a secondary shortwave trough behind it will quickly move across the PacNW. Little precipitation will be associated with these systems, however the WA Cascades are expected to see isolated light showers develop in the afternoon. Otherwise, the main impact from these systems are going to be an increase in breezy conditions across the lower elevations and through the Cascade gaps. The strongest winds are expected through the Kittitas Valley, where sustained northwest winds of 25-35mph and gusts up to 50 mph are forecast through the afternoon and evening (confidence 75-85%). In the Eastern Gorge, OR Columbia Basin, and the Simcoe Highlands westerly winds of 20-30mph with gusts mainly 35-40mph(isolated gusts up to 45mph) will develop by the afternoon. Elsewhere, winds of 15-25mph with gusts up to 35mph will develop. By Tuesday morning, upper level ridging in the northeast Pacific will build into the PacNW, providing another round of warming temperatures and dry conditions through the mid-week. Winds will generally be light through Tuesday, though a weak marine push in the afternoon will result in breezy northwest winds developing through the Kittitas valley. Lawhorn/82 .LONG TERM...Wednesday Through Sunday...Deterministic models and ensembles are in good agreement on the 500 mb pattern for Wednesday and Thursday depicting NW upper flow over the region. The GEFS ensemble depicts shortwave energy moving along the Canadian border Thursday afternoon and evening with lowering heights across the Pacific Northwest. This is forecast to tighten the pressure gradient with the latest GFS pressure gradient between PDX and GEG reaching 12 MB from 00Z-06Z Friday. This will favor windy west winds across the lower elevations Thursday evening. Latest Probabilistic NBM is indicating a 40-70% chances for winds exceeding 45 mph in gusts for much of the lower elevations Thursday evening. Friday through Sunday the confidence in the forecast becomes lower. There is considerable variability among the ensemble clusters in the depth/location of the upper troughs and ridges each day. However there is reasonable confidence (50-60%) that a surface cold front will cross the region on Friday bringing another bout of gusty westerly winds across the lower elevations during the afternoon and evening. Probabilistic NBM is indicating a 30-60% chances for winds exceeding 45 mph in gusts for the typically windy spots under westerly wind regimes. The suite of available guidance is consistent in showing that the threat for significant precipitation is very low through the entire forecast period (80% confidence). The NBM introduces 15-25% POPS along the Cascade East Slopes and northeast mountains on Sunday with minimal QPF (less than .05 inches). Probabilities of thunderstorms Sunday afternoon are currently quite low (5-8%). It will be warm on Wednesday and Thursday with high temperatures in the mid to upper 80s lower elevations. Friday through Sunday high temperatures in the lower elevations will be in the 70s to lower 80s. 78 && .AVIATION...00Z TAFs...There are a few cumulus clouds this afternoon with bases around 6-8 kft, and there will be more cumulus with similar bases on Monday. High level cirrus AOA 18 kft will also increase across eastern WA and northeast OR during the day. It has been breezy for many of the TAF sites today. Winds will decrease this evening, but winds will be the same or a little stronger on Monday. WNW 10-15 kt gusting to 20-25 kt on Monday. Wister/85 && .PRELIMINARY POINT TEMPS/POPS... PDT 51 74 47 74 / 0 0 0 0 ALW 55 78 50 77 / 0 0 0 0 PSC 57 82 52 82 / 0 0 0 0 YKM 52 77 47 82 / 0 0 0 0 HRI 55 80 50 80 / 0 0 0 0 ELN 50 68 45 77 / 0 0 0 0 RDM 43 71 40 74 / 0 0 0 0 LGD 46 72 43 72 / 0 0 0 0 GCD 44 74 41 74 / 0 0 0 0 DLS 55 74 49 80 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...Wind Advisory from 11 AM to 11 PM PDT Monday for WAZ026. && $$ SHORT TERM...82 LONG TERM....78 AVIATION...85