Area Forecast Discussion
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
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
583 FXUS65 KBOU 170944 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 344 AM MDT Wed Jul 17 2024 .KEY MESSAGES... - Scattered showers and thunderstorms today, with a slight uptick in storm intensity and some severe threat. - Temperatures a few degrees below normal for a change today. - More typical summer weather through next weekend with scattered afternoon showers and storms most days. Temperatures slightly above normal Thursday and Friday, then a few degrees below normal for the weekend into early next week. && .SHORT TERM /Through Thursday/... Issued at 343 AM MDT Wed Jul 17 2024 Satellite shows somewhat drier air aloft has moved over the area, while at the same time the low/mid levels had moistened a bit from 24 hours ago. At the surface, a weak surge was noted pushing across northeast Colorado in these early morning hours, and is attempting to support the development of an isolated shower/storm. The surge/front will also act to enhance the low level easterly upslope flow and keep moisture advection in place today. With plenty of morning sunshine, we expect the airmass to destabilize sufficiently to bring a round of scattered to numerous showers and storms this afternoon and early evening. It could be a fairly early start as well, with convective temperatures (per forecast soundings) being reached late this morning over the higher terrain and by noon or shortly thereafter on the adjacent plains/I-25 Corridor. The models have kept the highest instability east of the I-25 Corridor, and that`s where CAMs are a bit more promising regarding strength of storms and a low severe threat. That said, if the push this morning ends up being a little stronger then a small threat of a stronger/low end severe storm would be possible closer to I-25. In any case, the bulk shear profiles are also marginal, and it appears MLCAPE will be limited to about 1000-1500 J/kg in the main instability axis - most likely over the plains. Overall, we`ll show the highest PoPs in the mountains early to mid afternoon, shifting to the I-25 Corridor by mid afternoon, and then the eastern plains late this afternoon and early evening. A weak disturbance as seen in the QG fields should support a bump in shower/storm coverage, as well as serving to push a somewhat organized area of convection east of the I-25 Corridor before 5-6 pm. Then clearing can be expected tonight with low temperatures near normal. Highs today will be a few degrees below normal, with mid and a few upper 80s on the plains, and upper 60s and 70s in the mountains, foothills, and high valleys. && .LONG TERM /Thursday night through Tuesday/... Issued at 343 AM MDT Wed Jul 17 2024 On Thursday, the 500 MB high will be centered just west of the Four Corners with a north-northwesterly flow aloft over the CWA. Models are showing some drying at lower and mid levels which should result in a decrease in coverage and intensity of shower and thunderstorm activity. Most of the storms should be underwhelming with only light to moderate rain and gusty winds. However, there is the potential for one or two stronger storms with locally heavy rainfall and small hail across the plains, mainly east of the Front Range Urban Corridor during the afternoon and evening hours. On Friday, we may see a better chance for precipitation across the forecast area due to a slight increase in moisture combined with a passing shortwave. Some of the stronger storms, east of the Continental Divide could produce locally moderate to heavy rainfall, hail and gusty winds. Over the weekend into early next week, the upper high amplifies as it shifts westward over the Intermountain West. This pattern will place Colorado under the influence of a northerly flow aloft with upper level shortwaves moving south across the Central Plains States. This setup should allow a couple of cold fronts to move across the Northeastern Plains, resulting in cooler and unsettled weather across the area. At this time, PW`s and instability behind the surges appear to be somewhat lackluster. Therefore, most of the precipitation may be showery in nature with limited precipitation amounts. In this type of pattern, the greatest forcing and moisture convergence is usually focused from the Continental Divide eastward across the Southern Foothills and Palmer Divide. Consequently, some stronger storms with locally heavy rainfall and small hail will be possible, mainly in these areas. && .AVIATION /06Z TAFS through 06Z Thursday/... Issued at 1156 PM MDT Tue Jul 16 2024 Main concern will be thunderstorms on Wednesday afternoon and early evening. Guidance suggests another pretty early start to convection (around 20Z), and at least scattered coverage. That`s enough to have TEMPO VRB winds gusting to 35-40 kts and -TSRA in the forecast...starting at KBJC and KAPA by/shortly before 20Z, and 21Z at KDEN. Most storms should be out of the area again before 00Z, with only a small chance thereafter. Outside of the storms, fairly normal diurnal wind patterns and VFR conditions will prevail. && .HYDROLOGY... Issued at 343 AM MDT Wed Jul 17 2024 Model soundings show slightly lower LCLs today resulting in a slightly deeper warm cloud depth of 2000-2500 ft. Precipitable water values increase to 1-1.20" for the plains and 0.45 - 0.65" for the high country. As a result, stronger storms will be capable of locally heavy rain. Overall, the threat of flooding remains relatively low as storms should be outflow driven and moving about 20 mph. There will be a limited threat of flash flooding for the 2020 burn scars given the uptick in moisture, as the locally stronger storms in the high country will be capable of producing a quick one half to three quarters inch of rain in 30 minutes. Isolated stronger storms on the plains could produce 1 to 1.5 inches of rain, but most areas will see much less. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Barjenbruch LONG TERM...JK AVIATION...Barjenbruch HYDROLOGY...Barjenbruch