Sunrise 6:02 AM   Sunset 7:53 PM Moonrise 12:00 AM   Moonset 7:57 AM

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FXUS65 KBOU 281748 AFDBOU

Area Forecast Discussion National Weather Service Denver/Boulder CO 1148 AM MDT Sun Apr 28 2024

KEY MESSAGES

- Not as cool today with a chance of showers and thunderstorms this afternoon and early evening. Alpine areas could see an additional 1 to 4 inches of snow.

- Warmer and drier conditions to start the week.

- Turning to cooler and possibly wetter Wednesday and Thursday.

UPDATE
Issued at 1056 AM MDT Sun Apr 28 2024

Northwesterly winds are developing across most of the plains at this time. There was small batch of light rain showers over Urban Corridor earlier this morning, but they dissipated now. The foothills and western half of the plains are receiving fairly decent sun at this time. There is more cloudiness elsewhere for the CWA

Models are showing some lower end MLCAPE values for the CWA this afternoon, with nothing much above 400 J/kg. Soundings off ACCARS are showing about that assuming it can get to 56 F at DIA this afternoon. The models are showing limited convection into the early evening hours. Current pops aren't too bad so will make minor adjustments, especially early where there is no convection currently.

SHORT TERM /Through tonight/
Issued at 302 AM MDT Sun Apr 28 2024

The upper low this morning is presently over far northeast CO this morning and will continue to lift northeast into central NE by this afternoon. Lows clouds and maybe some patchy fog this morning, but that should decrease after sunrise. The best chance of showers this morning will be in the vicinity of the trough in the far northeast plains, and in the mountains. The flow aloft will remain northwesterly this afternoon with enough moisture and instability to produce additional showers as well as some thunderstorms. The HiRes models all indicate some decent cell development, with sfc based CAPES of 250-600 j/kg and mid level lapse rates over 8 C/KM. In addition, brisk northwest winds will develop across the plains with gusts up 35 mph possible this afternoon. For this evening, the models maintain some qpf through this evening, then it tapers off overnight. High temperatures today will be on the cool side, but 10-12 degrees warmer than Saturday.

LONG TERM /Monday through Saturday/
Issued at 302 AM MDT Sun Apr 28 2024

Weak upper level ridge to move across the Central Rockies Monday bringing dry and mild conditions. High temperatures are expected to top out around 70F across northeast Colorado. For Monday night, a weak trough moving across Wyoming and jet will provide lift to produce an area of rain and high mountain snow over southern Wyoming and the north central Colorado mountains late Monday night and early Tuesday morning. Westerly flow around the base of the trough will produce a downslope flow east of the mountains, bringing the precipitation to an end Tuesday morning. Expect breezy conditions over the mountains and foothills Tuesday. It will be another mild and dry day Tuesday with highs again around 70F degrees over northeast Colorado.

Upper level trough will track across the Northern and Central Rockies Wednesday and Thursday. Model trends have been all over the place with the track and strength of the system. The ECWMF had been tracking slow, stronger, and farther south, until the 00Z run, which is weaker and drier over Colorado. The GFS which was the weaker model and showed this system staying farther north is now the stronger and slower model. All said, confidence in the forecast for Wednesday and Thursday is low. Temperatures should trend cooler with the trough and cold front moving through the region. Chances for precipitation and amounts are still very unclear, so will go middle of the road with PoPs of 30-60 for Wednesday and Thursday.

For Friday, northwest flow aloft will prevail behind the upper level low east of Colorado. Temperatures begin to rebound Friday, but should stay somewhat cool under the northwest flow with highs in the lower to mid 60s over northeast Colorado. Current pattern depicted by the GFS and ECMWF favor dry conditions for Friday, though given the amount of uncertainty in the pattern prior to Friday, will keep the 20-30 PoPs in the forecast from the NBM.

For the weekend, flow aloft will turn westerly for Saturday and then southwesterly for Sunday. Temperatures will continue to warm each day under this pattern with highs returning to the 70s over northeast Colorado Sunday. Models show a weak trough passing north of Colorado Saturday with a cold front dropping south across Colorado, this help keep highs in the 60s. Can't rule out isolated to scattered storms behind the front this far out, so will roll with low PoPs.

AVIATION /18Z TAFS through 18Z Monday/
Issued at 1147 AM MDT Sun Apr 28 2024

Models have weak downsloping surface winds at DIA this afternoon.
Weak normal drainage wind patterns are expected overnight. Will leave the "VCSH" in at this time, however the airmass needs to warm up a bit to hit the convective temperature. If some showers do develop, variable direction outflow winds gusts to 40 knots are possible.

BOU WATCHES/WARNINGS/ADVISORIES
None.

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