Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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176 FXUS65 KBOU 171620 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 1020 AM MDT Fri May 17 2024 .KEY MESSAGES... - Much warmer and drier today. Only isolated high based shower/storm possible mainly in the mountains. - Breezier Sunday into Monday. - Cooler, unsettled pattern with increasing precipitation chances across the region early next week. && .UPDATE... Issued at 1020 AM MDT Fri May 17 2024 Satellite shows mostly sunny skies across the forecast area. Temperatures were responding quickly to the sunshine, weak downslope flow, and shallow inversions. We`ve already warmed into the mid 70s as of 10 am across the plains, and well on our way to the mid 80s and summerlike warmth today. There is some mid level moisture noted in the water vapor and IR satellite imagery skirting through northern Utah and into northwest Colorado this morning. As a result, we will be adding some low PoPs for most of the northern mountains this afternoon and early evening. Most of these would be only isolated very light showers/sprinkles, but can`t totally rule out an isolated rumble or two of thunder. Plains should see scattered virga and gusty outflow winds to around 35 mph possible. Finally, we`ve received fuel status updates from our fire weather partners. Not surprisingly, the greenup appears sufficient now to reduce any significant wildfire threat due to the breezier conditions Sunday into Monday. && .SHORT TERM /Through tonight/... Issued at 223 AM MDT Fri May 17 2024 Water vapor imagery shows a very dry airmass entering Colorado as well as upper level ridging. Colorado will be under the right exit region of a jet that moves over Wyoming today. This will lead to strong subsidence and the vast majority of our forecast area will be dry as a result. Some high resolution models indicate that very weak instability in the late afternoon could lead to a few virga showers. Some of these could create brief wind gusts and perhaps a few rain showers could make it to the surface. The strong subsidence aloft and downslope, westerly winds at the surface will lead to very warm conditions across the urban corridor and plains. Highs will reach well into the 80s and it is even possible a location or two could reach 90 in the usual warm spots in the South Platte River Valley. The record high for Denver is 91 and that is out of reach. The only minor weather concern today is elevated fire weather conditions across northern Larimer and Weld Counties. Minimum relative humidity will drop to as low as 12 percent there and wind gusts could reach 25 mph. Across the rest of the plains, winds will be too light to increase fire weather conditions. && .LONG TERM /Saturday through Thursday/... Issued at 333 AM MDT Fri May 17 2024 Cooler weather is expected Saturday behind a weak cold front. This should keep highs in the 70s across most of the plains, though a few of our warmer spots still could reach 80F. Main question for Saturday is how much moisture lingers across the region behind the front, and what that looks like for a PoP forecast. Pretty good confidence that the high country (especially along/south of I-70) sees typical afternoon showers and storms, with lower confidence along/east of I-25. High resolution guidance supports at least widely scattered convection across the plains by the late afternoon hours which is reflected in the current grids. Sunday should be warmer and drier as westerly flow aloft begins to gradually strengthen ahead of a trough axis. The added downslope component to the flow should usher out any lingering moisture with the best chance of any showers/storms confined towards the Wyoming border. Highs again should rebound into the upper 70s to low 80s across the lower elevations. Southwesterly flow aloft will increase Monday as the trough axis approaches, with a lead shortwave expected to eject into the Central Plains from Monday into Tuesday. A surface low is generally expected to form across southern Colorado on Monday afternoon and quickly shift east... with a strong cold front expected behind it. There are still a few questions about the timing and evolution of the primary shortwave (and the overall synoptic pattern) which will ultimately influence the mesoscale environment as well. While it`s a fairly low confidence forecast period, the overall pattern does look quite favorable for cooler/wetter weather across the forecast area. Model guidance gradually diverges by mid/late next week. The mean pattern would favor zonal flow with enough moisture embedded to support isolated/scattered showers and storms, mainly across the higher elevations. Temperatures in this period look to be near normal. && .AVIATION /12Z TAFS through 12Z Saturday/... Issued at 524 AM MDT Fri May 17 2024 VFR through the TAF period. Drainage flow this morning will weaken and turn more to the west/west-northwest by early afternoon. Generally expect winds to be 10kt, but there will likely be lulls and times where gusts approach 20kt. Light westerly flow will continue this evening into the early overnight hours. A weak cold front will try to push towards the terminals overnight with a shift to the north or northeast possible after 09z. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Barjenbruch SHORT TERM...Danielson LONG TERM...Hiris AVIATION...Hiris