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
065 FXUS65 KBOU 130930 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 330 AM MDT Mon May 13 2024 .KEY MESSAGES... - Drier/warmer Monday, with scattered mountain showers/storms and more isolated coverage for lower elevations. Snow levels should be around 11,000 ft MSL - Scattered afternoon/evening thunderstorms Tuesday, most numerous in the mountains and decaying as they push east. - Front bring cooler and wetter weather on Wednesday. - Warmer and generally drier starting Thursday, with lesser but at least isolated daily afternoon showers/thunderstorm coverage, highest for the mountains. && .SHORT TERM /Through tonight/... Issued at 330 AM MDT Mon May 13 2024 Mostly clear conditions are noted on the satellite pictures at this time. Winds are fairly weak across the forecast area as well. Temperatures in in the upper 30s to mid 40s F over the plains currently, with 30s in the foothills and 20s to mid 30s in the mountains. Models have upper ridging over the CWA today and tonight with fairly weak northerly jet level flow today. It will become northwesterly tonight. The QG fields show weak downward to neutral synoptic scale motion today and tonight. The low level wind proggs indicate normal drainage wind patterns expected with fairly weak speeds both today and tonight. Looking at moisture, it has dried out a bit from yesterday, with precipitable water values progged in the 0.35 - 0.80 inch range today and tonight. There is some CAPE around late in the day, with the highest values over the mountains, foothills and immediate plains, but it is not significant. There is some warming aloft and instability is not great overall. Will leave the highest late day pops in the mountains and foothills with 20-50%s and will go with 10-20%s over the immediate plains. For temperatures, todays highs look 4-6 C higher than yesterday`s highs. I went with lower to mid 70s over the plains. && .LONG TERM /Tuesday through Sunday/... Issued at 135 AM MDT Mon May 13 2024 Zonal flow takes hold aloft on Tuesday as the weak ridge axis departs into the Midwest, keeping a modest stream of mid-level moisture in place over the region. Simultaneously, light downslope flow off the Front Range below 700 mb will allow for marginal additional warming across the lower elevations, where temperatures with climb into the mid to upper 70`s. Weakly unstable conditions will open the door to scattered afternoon convection developing over the high country, then migrating east over the urban corridor. These storms should find it rather hard to sustain their intensities as they push off the higher terrain, so precipitation chances will drop progressively with increasing distance from the mountains. Warm and relatively dry near-surface conditions will provide for DCAPE values of 700-1,000 J/Kg, thus supporting some locally gusty outflow winds from decaying storms as they drift eastward. The approaching upper-level trough moves promptly overhead on Wednesday, and the associated surface cold front is slated to push through likely some time Wednesday morning, although there are still a few differences in timing among the guidance. Highs on Wednesday should be a healthy 10 to 15 degrees below Tuesday`s values as a result. With light northeast flow prevailing in the post-frontal environment, we`ll have a modest upslope component through the day, aiding in the development of mostly stratiform precipitation as it taps into a partially saturated vertical profile. Therefore, not surprisingly, the higher precipitation totals should be focused along the lee of the Front Range, foothills (especially southern), Denver metro, and Palmer Divide, with amounts between 0.20-0.70" looking fairly reasonably as an area-wide average. Latest guidance has trended slightly drier however, so we`ll have to keep an eye on that trend moving forward. It`s worth mentioning that vertical temperature differentials still seem sufficiently high to generate enough instability for a few embedded convective elements in the afternoon. The coldest air looks to remain farther north as this system moves through, but snow levels could nonetheless lower to about 9,000 ft, so potential for locally impactful snow accumulations will still need to be monitored for the higher elevations. The trough exits to the east by Thursday, though northwest flow aloft on the backside will support a low chance (~20%) for a few weak afternoon showers/storms, primarily in the high country. Temperatures will start to rebound as well, with some parts of the plains and urban corridor potentially bouncing back into the 70`s. Warming accelerates Friday into Saturday as a thermal ridge expands over the Rocky Mountain region. Scattered afternoon showers/storms look reasonable each day, but no signals at this time for any overly wet or severe weather pattern. && .AVIATION /06Z TAFS through 06Z Monday/... Issued at 1229 AM MDT Mon May 13 2024 Watching an outflow moving westward towards DIA from the east at this time. I put a wind shift in the DEN TAF for it, however, it is slowing down and fading away. I doubt it will make it. Current winds at DIA are more westerly than the normal drainage patterns for this time of the night. Models show weak winds at DIA through the morning hours with some north to east directions this afternoon and early evening. Little to no convection is expected later today and this evening. There should not be any ceiling issues. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...RJK LONG TERM....Rodriguez AVIATION.....RJK