####018005490#### FXUS66 KPDT 162245 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 345 PM PDT Thu Jul 16 2026 .KEY MESSAGES... - Isolated thunderstorms over the Blue Mountains and their adjoining foothills this afternoon and evening. The environment is supportive of isolated strong to severe storms, capable of producing gusty outflow winds and hail. - Breezy to windy this afternoon and evening, then breezy Friday. - Predominantly above-normal temperatures likely (50-80% confidence) to persist through next week. && .DISCUSSION... Water vapor imagery shows a deep closed low churning offshore in the vicinity of 45.6N, 126.5W this afternoon. Meanwhile, a broad ridge of high pressure is located over the western CONUS, leading to southerly to southwesterly winds aloft over the forecast area. Monsoonal moisture from the Southwest is still present over the region with RAP-based Mesoanalysis suggesting PWATs of 1-1.2" over the Blue Mountains and their adjoining foothills. Coupled with ample surface moisture (dew points in the upper 40s to lower 60s from surface observations), sufficiently steep mid-level (700-500 mb) lapse rates of 7-8 C/km, and modest synoptic-scale forcing associated with the upper low, the environment is primed for additional shower and thunderstorm development through the evening. The northern Blue Mountains, their foothills, and Wallowa County are under a Marginal risk of severe thunderstorms per SPC's latest forecast, with the main hazards being severe outflow wind in excess of 50 kts and hail up to 1" in diameter. DCAPE 1300-1500 J/kg is strongly supportive of gusty outflow winds with any stronger convection that develops. A strong cross-Cascade temperature gradient (25-30 degrees), marine layer on the west side, and cross-Cascade pressure gradient should support widespread breezy to windy westerly to northwesterly winds through the Cascade gaps and into the western portion of the Columbia Basin through the evening and into the overnight period. Have issued wind advisories for the aforementioned area through 08Z tonight. Looking ahead, confidence is very high (95%) that the upper low will lift northeast into British Columbia through tomorrow and into the weekend. Breezy winds will continue through the Cascade gaps each day, and lower RH on Friday may lead to localized overlap of critical wind/RH (see Fire Weather discussion below). Heading into next week, there is still uncertainty in details of the 500-hPa pattern, but confidence is medium-high (50-80%) in predominantly above-normal temperatures across the forecast area as the region remains under the influence of a broad ridge of high pressure over the western CONUS. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...VFR conditions to prevail through the period. Showers and thunderstorms are expected to develop over areas of the Blues and eastward. There remains a low chance (<10%) of showers/thunderstorms impacting sites PDT/ALW/PSC through this evening and overnight. Breezy to gusty west winds will impact site DLS through the period, with strongest winds expected through 05Z. Breezy winds at sites PDT/RDM/BDN/ will persist through this evening, becoming light through the remainder of the period. Light winds will prevail at all other sites. Lawhorn/82 && .FIRE WEATHER... Isolated thunderstorms are expected to continue through this evening, mainly over the Blue Mountains. Stronger thunderstorms will be capable of producing strong, gusty, and erratic outflow winds in excess of 60 mph. Tonight into early Friday, there is a very low chance (15% or less) of additional high-based showers and isolated thunderstorms over the Blue Mountains and eastern half of the Columbia Basin. Breezy to windy westerly to northwesterly winds of 15-30 mph with gusts of 25-45 mph will persist through the Columbia Gorge and into the Basin through early Friday, but RH should remain above critical values so no Red Flag Warnings have been issued. Warm, dry, and locally breezy conditions are then forecast Friday through the weekend with very low chances (15% or less) of showers or thunderstorms. Portions of the eastern Columbia River Gorge and western half of the lower Columbia Basin of Oregon may (50% confidence) flirt with overlap of critical wind/RH Friday afternoon and evening. && .Preliminary Point Temps/PoPs... PDT 56 90 57 91 / 0 0 0 0 ALW 63 92 63 93 / 10 0 0 0 PSC 61 94 60 95 / 0 0 0 0 YKM 59 93 59 94 / 0 0 0 0 HRI 59 92 61 94 / 0 0 0 0 ELN 56 88 56 86 / 0 0 0 0 RDM 46 89 50 91 / 0 0 0 0 LGD 58 93 57 93 / 20 0 0 0 GCD 54 96 54 95 / 0 0 0 0 DLS 58 87 60 90 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...Wind Advisory until 1 AM PDT Friday for WAZ024. Heat Advisory until 9 PM PDT this evening for WAZ026>029. Wind Advisory until 1 AM PDT Friday for WAZ026. OR...Wind Advisory until 1 AM PDT Friday for ORZ041-510. Heat Advisory until 9 PM PDT this evening for ORZ044-049-050- 507. Wind Advisory until 1 AM PDT Friday for ORZ044. && $$ DISCUSSION...86 AVIATION...82 FIRE WEATHER...86 ####018005014#### FXUS65 KBOU 162248 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 448 PM MDT Thu Jul 16 2026 .KEY MESSAGES... - Hot weather continues with the heat now expected to last through Monday. The highest temperatures will occur Sunday and Monday with a Heat Advisory for the urban corridor possible. - Scattered afternoon/early evening storms in the mountains expected through Sunday with the plains remaining dry. - Significant monsoonal moisture and cooler temperatures will arrive on Tuesday of next week. The thunderstorms that develop will be capable of producing locally heavy rainfall. && .DISCUSSION /Through Thursday/... Issued at 1200 PM MDT Thu Jul 16 2026 Water vapor imagery shows a very weak shortwave trough over northeast Colorado moving southwestward with plenty of dry air aloft. At the surface, there are warm temperatures and decently high moisture values given the warmth. With very steep lapse rates and most-unstable CAPE approaching 1,000 j/kg over the mountains, widespread thunderstorms are expected in Park County with scattered coverage in Grand and Summit Counties. Some storms could have nickel size hail in South and Middle Parks. In addition, multiple rounds of storms could lead to rainfall totals around an inch in Park County. Otherwise, some isolated showers or storms could develop in the southern foothills. It is unlikely but possible that a storm or two moves onto the adjacent plains in the southwest Denver metro which could produce some wind gusts up to 35 mph this evening. Slightly warmer temperatures aloft with less moisture will lead to an increase in surface temperatures by a degree or two on Friday with less coverage of showers and storms over the mountains. A ridge of high pressure aloft will strengthen on Saturday and Sunday and place itself directly over Colorado. 500 mb heights will increase to around 594 dm over our CWA on Saturday and up to 596 dm on Sunday. High temperatures will increase as a result and highs will be 96-98 in the downtown areas of Denver, Fort Collins, and Greeley on Saturday. The warmest day of the 7-day forecast appears to be Sunday as highs in the downtown areas of those three cities will be between 99-101. The latest HeatRisk forecast value for Sunday shows most of the urban areas will have a value of 3. If models continue to show this level of heat tomorrow, a Heat Advisory may be issued for the urban corridor for Sunday. One of the bigger forecast changes over the past 24 hours is the delay in the arrival of the monsoonal moisture and cooler temperatures. The ECMWF ensembles now have a much tighter range of forecast high values with the 25th percentile in Denver of 97. This is likely due to a slight shift with the center of the upper level ridge to the northwest throughout the forecast runs. If this trend continues, it is possible that high temperatures will be around 100 degrees again in urban areas with a HeatRisk value at 3 on Monday. That means, a Heat Advisory will again be considered for Monday. Showers and storms will increase in coverage over the higher terrain on Monday as more monsoonal moisture makes its way northward. But it is not until Tuesday that the plains will begin to see better coverage of showers and storms. With the upper level ridge shifting to the south, there will be light westerly flow aloft which will allow storms to move off the higher terrain and onto lower elevations. The storms Tuesday night and into Wednesday will have ample moisture and moderate instability. It does look like the first couple of days that this monsoonal moisture arrives will have a flash flooding concern due to heavy rainfall. && .AVIATION /00Z TAFS through 00Z Saturday/... Issued at 444 PM MDT Thu Jul 16 2026 VFR conditions will prevail for all terminals through the TAF period. ESE winds will continue to persist at the terminals through early this evening with gusts generally in the 19-25 kt range. Latest guidance has accelerated the rotation to southerly drainage flow this evening, so the TAFs reflect this quicker transition. Ongoing convection across Park County could induce some sw-erly outflows after ~01Z, with corresponding impacts to KAPA in the form of occasional gusts 25-30 kts, however confidence is low. This potential is notably lower for the other two terminals. Tomorrow, expect very similar diurnal wind patterns with development of robust E/ESE flow by early afternoon. An isolated high-based shower and associated outflow wouldn't be out of the question later in the day, but neither confidence nor projected coverage are high enough to warrant any explicit inclusion in the TAFs. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Danielson AVIATION...BRQ