147 FXUS65 KBOU 110950 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 350 AM MDT Thu Jul 11 2019 .SHORT TERM...(Today and tonight) Issued at 250 AM MDT Thu Jul 11 2019 A small moisture tongue moved over areas east of I-25 this morning increasing dew points to the mid to upper 50s. This moisture is rather shallow and should mix out quickly this morning with the aid of downslope winds and strong solar radiation. Models indicate the moisture will not fully mix out east of line from Limon to Akron as a weak dryline will develop during the afternoon. Convergence will be weak along this dryline but it may be just enough to create a few showers and storms. I added POPs mainly in Washington and Lincoln Counties so that the forecast will mention a slight chance of afternoon storms. Elsewhere, isolated showers and storms will develop mainly over the mountains and foothills. Inverted V soundings and large downdraft CAPE values indicate that these showers and storms will produce gusty winds up to 40-45 mph. Any showers and storms should dissipate shortly after sunset. High temperatures will be about 5 degrees above normal. Some areas in the South Platte River Valley near the Nebraska border may reach 100 degrees. .LONG TERM...(Friday through Wednesday) Issued at 250 AM MDT Thu Jul 11 2019 A ridge of high pressure will prevail over Colorado through the period. Friday through Monday the center 500 mb, 594 dam ridge is expected to stick around southeastern CO/northeastern New Mexico. This will allow for a weak southwesterly flow aloft to be over the forecast area which will advect subtropical moisture from the Desert Southwest into the region. GFS/NAM12 Layer Precipitable Water values increase through the period. In the mountains, PW values will be around 0.50 in. on Friday afternoon, then around 0.80 in. Sunday afternoon. Similarly across the northeast plains, 0.80-1.0 inch on Friday, increasing to 1.1-1.2 inches over the weekend. The weak flow aloft will increase the risk of flooding as well. Greater thunderstorm coverage is forecast by the weekend in addition to an increasing threat of heavy rainfall. Wet microburst thunderstorms the main concern, a few of which could produce marginal severe threat with gusts in the 50-60 mph range in addition to a localized flood risk. This already addressed in the previous package so overall no significant adjustments to the grids. This unsettled pattern will continue into early next week. By Wednesday however, the ridge is expected become stretched more west to east which could produce a drier westerly flow in the mid levels and pinch off the subtropical moisture plume. Consequently, less thunderstorm coverage will be possible by midweek. With the ridge expected to remain over the region, high temperatures will be locked in the lower to mid 90s across the urban corridor and northeast plains through the period. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 250 AM MDT Thu Jul 11 2019 VFR conditions will continue through Thursday night. Drainage flow will continue into the mid morning hours. Light winds will shift out of the northeast around midday. A few isolated showers and storms are possible over the mountains this afternoon. It is possible that these produce gusty winds that reach one of the airports but the chances remain rather small due to the limited extent of these storms. Winds return to drainage overnight. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Danielson LONG TERM...Cooper AVIATION...Danielson