Area Forecast Discussion
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
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559 FXUS65 KGJT 021137 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 537 AM MDT Sun Jun 2 2024 .KEY MESSAGES... - Isolated to scattered thunderstorm development remains a threat each afternoon through through Monday with gusty outflow winds more likely than wetting rainfall. - Afternoon showers and thunderstorms return Thursday into next weekend favoring the higher terrain. - Temperatures remain above normal today and into the coming week. The warmest temperatures of the season thus far will be Thursday and Friday at 10 to 15 degrees above normal. - The warmer temperatures means runoff will be well underway with most major stem rivers showing rises over the next several days. && .SHORT TERM /THROUGH MONDAY/... Issued at 329 AM MDT Sun Jun 2 2024 The weather pattern we`ve had for the past week will continue for another couple days with the zonal flow aloft and diurnal heating driving orographic showers and thunderstorms over the higher terrain. Drier air is moving into the southern areas of the region that will significantly limit any convection in the San Juans today and tomorrow. The stream of Pacific moisture to the north continues to dip south to feed the shower and thunderstorm activity along and north of the I-70 corridor. A weak shortwave embedded in the flow will help support convecting this afternoon, and we may see an isolated stronger storm, but lack of upper-level dynamics should keep most of the activity on the tame side with the primary threat continuing to be strong outflow winds gusting 35 t 45 mph. Convection will die out through the early evening with mild weather overnight. Tomorrow will see a similar pattern with afternoon showers and thunderstorms along and north of the I-70 corridor, but with the approach of a more active shortwave that will move through overnight Monday (more on this system below in the long term discussion), expect to see the storms to generally strengthen going into the evening. Temperatures Today and tomorrow will continue about five degrees above normal && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 329 AM MDT Sun Jun 2 2024 The base of a shortwave trough will edge into our northern CWA and pass through Monday evening, allowing for showers and some isolated thunderstorms to continue through Monday night across the north. Moisture remains elevated and the northern mountains stand the best chance at seeing wetting rain, not snow, as the temperatures stay fairly mild. The lower elevations look to see trace amounts with gusty winds the better bet. This shower and storm activity should clear out by Tuesday morning as a ridge of high pressure builds out west and drier northwest flow takes hold. Tuesday should provide for highs a couple degrees cooler than Monday but still warm as we sit near normal across the north and about 5 degrees above normal along and south of I-70. The drier northwest flow should put an end to convection with not much forcing or instability to really get things going aside from perhaps some building cumulus over the high terrain and a few isolated storms but chances are fairly low for any convection Tuesday as a much more stable atmosphere moves in place. Same goes for Wednesday as the high pressure ridge moves east and builds overhead. Even drier air expected Wednesday as mixing ratios drop to below 2 g/kg. This is the start of a significant warming trend from mid to late this coming week as highs rise up 5 to 10 degrees above normal by Wednesday. Again, limited convective potential for any storms to form Wednesday. By Thursday and Friday, the ridge axis will have shifted overhead or just east of the Divide, allowing some subtropical moisture to advect northward as the flow becomes southwesterly. The fly in the ointment is a cut off low off the Baja Peninsula and how this impacts our weather as the models are struggle busting with how to handle this cut off low as it tries to force its way through the high pressure ridge. In the grand scheme of things, Thursday and Friday afford to be our hottest days thus far in 2024 as high temperatures climb to 10 to 15 degrees above normal. That`s right, we are looking at near to low triple digit heat for the lower Grand Valley and desert valleys of east-central and southeast Utah. Also, the rest of the lower valleys should see 90s, the higher valleys 80s and the mountain towns 70s. In addition to the heat, afternoon convection should crop up again Thursday afternoon, mainly along the western Colorado high terrain along the divide. By Friday and even Saturday, shower and thunderstorm coverage looks to expand as models try to move this cut off low into the ridge, some models breaking the ridge down and allowing this cut off low to draw more moisture and forcing into the region, while some models keep the high pressure ridge in place, almost forming a Rex Block as the cut off low remains over Arizona with the high pressure centered over the Great Basin. Time will tell how this plays out, but for the time being, higher confidence exists in the high temperature forecast with the projected heat. Low confidence exists for the shower and thunderstorm activity and how widespread it may be. Can pretty much at least bet on our typical afternoon storms favoring the high terrain primarily due to the southerly flow, afternoon diurnal heating and instability. Low levels still appear dry and with the heat sticking around and not much impact on temperatures, gusty outflow winds would be a better bet with any storm activity than wetting rain at this time. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 520 AM MDT Sun Jun 2 2024 Expect VFR conditions through the TAF period with high-based afternoon and evening showers and thunderstorms generally over the higher terrain north of I-70. Gusty outflow winds of 35 to 45 kts will again be the primary concern with any storm activity. Otherwise, winds will be light this morning becoming breezy westerlies after about 18Z. Winds drop off again overnight. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...DB LONG TERM...MDA AVIATION...DB