Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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405 FXUS66 KPDT 071002 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 302 AM PDT Sun Jul 7 2024 .SHORT TERM...Today through Tuesday...Little change in the forecast tonight as upper level ridging will dominate the synoptic pattern through the next several days. Water vapor imagery tonight shows the ridge slowly moving east, with the ridge axis inching ever closer onshore. As the ridge continues to move east, expect afternoon temperatures to increase another 1 to 3 degrees and morning lows to increase another 2 to 4 degrees through Tuesday. Confidence remains very high(90-100%) that widespread triple digit degree temperatures will develop by tomorrow in the lower elevations, with NBM probabilities showing a 60-75% chance that areas of the Columbia Basin, eastern Gorge, and the John Day Basin will reach or exceed 110 degrees Tuesday. As for HeatRisk values, today will see a mix of moderate to major, with major HeatRisk increasing areawide Monday and Tuesday and localized extreme HeatRisk developing Tuesday. Otherwise, the only other weather phenomena to note are increasing mid to upper level cloud cover Tuesday. Ensemble guidance and their deterministic counterparts indicate a weak vort and speed max coming up southwest flow aloft at 500mb, resulting in increased cloud cover at this layer. While the southwest flow aloft would bring concerns of thunderstorms, little to no moisture support is noted at all levels, resulting in very low confidence(< 10%) in any dry or wet thunderstorm development. Lawhorn/82 .LONG TERM...Tuesday through Saturday... Bottom Line Up Front 1. Breezy conditions return Wednesday. 2. Fire weather concerns Wednesday. 3. Continued dry and warm conditions. Models remain in firm agreement with the upper level high pressure system slowly migrating eastward. By Wednesday an upper level off shore weak trough will set up allowing for a slight ridge breakdown and a shift in the upper level winds. Looking at the pressure gradient tool, there is 9 to 10 mb difference between PDX and GEG which leads to the conclusion that Gap winds will set up. Looking at the raw ensembles, between 60 to 70% show that winds will be between 15 to 20 mph through the Gorge, Kittitas Valley as well as along the lower Columbia Basin. With the warm temperatures and dry air residing over the region, relative humidities have dropped into the critical range with 90-100% of the raw ensembles showing relative humidities to be below 15%. This coupled with the slight increase in winds through the Gaps, fire weather concerns are elevated Wednesday between 11 AM and 8 PM with high confidence of 70-80%. Models show southwest flow to continue over the region even with the breakdown of the upper level ridge. The incoming upper level trough will bring with it slightly "cooler" conditions. EFI shows the region to remain well above the climatological normal with temperatures still averaging 10 to 15 degrees above normal with above normal overnight temperatures. Wednesday will be the hottest day of the long term with 73% of the raw ensembles showing the Pendleton area to be in the upper 90s to near 104 degrees, 81% showing the Basin to be between 105 and 110 degrees, 69% showing the Gorge in the upper 90s to near 100 degrees and 64% having central OR in the mid to upper 90s. Temperatures will decrease by 2 to 5 degrees by Thursday as the trough sweeps across and temperatures will remain through the period. Remain diligent with the heat. Find more ways to protect yourself and others at www.weather.gov/safety/heat. Bennese/90 && .AVIATION...12Z TAFs...VFR conditions will persist through the period with mostly terrain driven winds with the exception of a brief period of elevated winds at DLS/RDM/BDN. DLS will see increased winds after 21Z with sustained winds of 14 kts and gusts to 25 kts. RDM/BDN will see increased winds after 22Z of 10 kts and gusts of 20 kts. CIGs will remain out of sight with SKC. Bennese/90 && .PRELIMINARY POINT TEMPS/POPS... PDT 100 63 102 66 / 0 0 0 0 ALW 103 67 105 69 / 0 0 0 0 PSC 104 66 107 69 / 0 0 0 0 YKM 103 67 105 70 / 0 0 0 0 HRI 104 65 107 68 / 0 0 0 0 ELN 102 64 105 67 / 0 0 0 0 RDM 100 57 102 60 / 0 0 0 0 LGD 96 58 99 61 / 0 0 0 0 GCD 98 58 101 62 / 0 0 0 0 DLS 104 68 109 72 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning until 10 PM PDT Thursday for ORZ041-044- 505-507-508-510-511. Heat Advisory from noon Monday to 10 PM PDT Thursday for ORZ049- 050-502-503. Heat Advisory from noon Monday to 10 PM PDT Tuesday for ORZ509. WA...Excessive Heat Warning until 10 PM PDT Thursday for WAZ024- 026>029-521-523. Heat Advisory from noon Monday to 10 PM PDT Thursday for WAZ030. Heat Advisory from noon Monday to 10 PM PDT Tuesday for WAZ522. && $$ SHORT TERM...82 LONG TERM....90 AVIATION...90