Sunrise 5:32 AM   Sunset 8:23 PM Moonrise 2:06 AM   Moonset 1:55 PM

  Print   HELP   Reset   Save   Recall  New

FXUS65 KBOU 311137 AFDBOU

Area Forecast Discussion National Weather Service Denver/Boulder CO 537 AM MDT Fri May 31 2024

KEY MESSAGES

- Chance of more storms today, a few could be severe with the greatest threat over the Palmer Divide into East Central Colorado.

- Severe storm threat again on Saturday, turning warmer.

- Hottest temperatures of the year Sunday into early next week, along with drier weather.

SHORT TERM /Through tonight/
Issued at 353 AM MDT Fri May 31 2024

After last night's significant Denver hailstorm, showers and storms pushed slowly east across the plains, and continue in these pre-dawn hours. The next batch which came in from the northwest appeared to have some forcing going for it with a cold front/enhanced convergence, and some lift in the right rear entrance region of a departing speed max. As the front continues to undercut that, there will be a gradual weakening and diminishing trend in the early morning hours.

For late this afternoon and evening, there is still a conditional threat of severe storms. The cold front early this morning will not help our cause for instability, as we'll see areas of stratus fill in behind it. That means somewhat cooler temperatures than originally forecast. The low level winds fields do turn from northerly to more easterly in the afternoon, which would support some modest warming. However, given this morning's frontal surge and slow recovery, we think if any place had a higher threat of warming/destabilization and convective initiation it would be the Palmer Divide into southeast Colorado. That said, the low level flow turns more southeasterly in the evening and could allow further destabilization and weakening cap. Given MLCAPE is advertised to climb into the 800-1500 J/kg range (if we do see more heating e.g. Td 72/48), and deep layer shear increasing to 50+ kts, a few supercells are possible with large hail being the primary threat again. Finally, with low level theta-e advection this evening and another speed max passing to our north, the severe threat could retreat northward as we head into the evening hours possibly spreading up toward the I-76 Corridor. The highest probabilities of anything severe would still be over the Palmer Divide to Limon and perhaps as far north as Akron.

Some drying is then noted overnight and with the passing speed max we think most of this convection will be ending before midnight.

LONG TERM /Saturday through Thursday/
Issued at 353 AM MDT Fri May 31 2024

Saturday could be yet another day of severe storm threat. In fact, it's looking more favorable for severe storms than it did just 12-24 hour ago. There is less drying noted aloft, and thus we'll see higher storm coverage. Granted, most of the storms over the mountains and along the I-25 Corridor will be higher based.
BUT...there is less lee troughing than previously advertised, and thus there is reasonable potential the low level moisture does not scour as far east as previously forecast. The severe threat for Saturday afternoon into early evening could be back as far west as the southern/eastern portions of Denver onto the adjacent plains, with the highest probability of severe storms toward Fort Morgan, Strasburg, and points east across the plains. MLCAPE is advertised to get a bump up with the warmer temperatures and still moisture advection over the plains, with 1400-2000 J/kg expected. Low level wind shear will increase, but hodographs right now are still fairly straight so hail and high winds will be the primary threats. But, it'll be the first of June and that could spell a couple landspouts too in typical first week of June fashion.

Summer heat will take hold by Sunday, with high temperatures pushing 90F across the I-25 Corridor and plains. We still can't totally rid ourselves of a severe threat over the northeast plains, but other locations in/near the Front Range will almost certainly be turning drier with a more pronounced downslope.
Models are still indicating a bit more mid/upper level moisture for Sunday, enough for some virga or light rain showers in/near the mountains especially toward the north.

For Monday and Tuesday, flat ridging in the westerly flow aloft is expected to keep temperatures warm, in the mid 80s to lower 90s. The airmass is looking too dry for showers or storms. On Tuesday, models are coming into better agreement showing a trough tracking across the Northern Plains. This will cause flow aloft to turn northwesterly and bring a cold front into the area by Monday night or Tuesday. The front should be fairly shallow though so still expect a warm day Tuesday. There would be just a slight (10-20%) chance of a storm.

For Wednesday and Thursday, an upper level ridge builds somewhere over the western half of the country. Models are still unclear where the ridge will set up. Expect warm conditions to continue Wednesday and Thursday though slight cooling may occur behind Tuesday's cold front. Chances for showers and storms continue to be low, with the vast majority of the ensemble members showing dry conditions continuing through Thursday. One of the outliers remains the operational GFS. It shows some subtropical moisture moving northward late next week. Can't rule this out, though this seems to be a stretch given what the other models show.

AVIATION /12Z TAFS through 12Z Saturday/
Issued at 537 AM MDT Fri May 31 2024

Stratus the main concern in the short term, then chance of storms late this afternoon and evening.

A weak cold front had moved across the area early this morning, with a stratus deck near 7500 ft MSL and MVFR developing across the Denver area TAF sites. Those conditions should persist most of this morning and last close to 18Z-19Z, but considering the relative breaks in the stratus to the east at the present time, it could break a couple hours earlier. Scattered showers/storms are possible in the late afternoon and evening (22Z-04Z), but coverage may very well be limited by low level stability behind the front.
We'll have a VCTS or Prob30 to account for the somewhat lower probability of storms today.

There is a low risk (20-30% chance) of stratus and IFR/MVFR redevelopment overnight tonight, considering the low level moisture in place and potential for weak Denver Cyclone.

BOU WATCHES/WARNINGS/ADVISORIES
None.

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Denver/Boulder, CO,