248 FXUS65 KGJT 271127 AFDGJTArea Forecast Discussion National Weather Service Grand Junction CO 527 AM MDT Sat Sep 27 2025
.KEY MESSAGES...
- Afternoon and evening convection continues each day through the weekend, possibly beyond. Sunday looks to be the most active day.
- Some storms may be capable of producing strong winds as well as heavy rainfall, which could impact the recent burn scars.
- Light snow can`t be ruled out for the highest elevations over the weekend though no impacts are expected to roadways.
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.SHORT TERM /THROUGH SUNDAY/... Issued at 258 AM MDT Sat Sep 27 2025
H500 hand analysis and satellite imagery is showing the closed low has migrated to the Baja region as anticipated while the northern stream wave is moving through the Northern Plains. Satellite derived PWAT suggests the SW cyclone is tapping into the SubTropics and possibly even pulling in moisture associated with Narda out in the EPac. The first spiral of this mositure looks to lift across our southern border by mid morning just slightly slower than thought yesterday. With the northern wave out of the picture we should get a better push of this moisture into the central CWA and precipitation chances reflect this today. Water vapor is showing a dry slot behind this spiral of mositure over central AZ this morning. Model dynamic trop and mid level moisture fields show this feature lifting across the 4 Corners by mid afternoon on the nose of a jet emerging on the downstream side of the low. The added ascent from these features and some insolation should help tap into the moderate instability and produce more organized convection. Heavy rainfall rates...hail and gusty winds will all be threats across the 4 Corners through the PM hours. Nocturnal convection is more likely tonight with this strong moisture continuing to lift northward along with any convectively forced mesoscale spins. The SoCal low will begin to lift northward on Sunday as a larger trough moves into the EPac. QG ascent increases ahead of this over our CWA as a result and with well above normal moisture in place it`s not hard to see why there will be a fairly good chance of widespread shower and thunderstorm activity. CAPE values in some of the CAMs are 700-1200 j/kg by the afternoon but not sure all of that can be realized with the amount of cloudiness in place. However there will be some probability of stronger storms again over the southern and western part of the CWA. Sunday has consistently been the apex of this event and will have to watch several burn scars and other areas for excessive runoff as well. Above normal temperatures today drop back toward normal tomorrow.
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.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 258 AM MDT Sat Sep 27 2025
Models have slowed down the arrival of the shortwave trough by about 12 hours the past fews runs, but despite that we are still expecting scattered to widespread showers during day. This could result in less forcing than previously anticipated. Another uncertainty is the amount of cloud cover in the morning, which will dictate how much instability can build for the afternoon convection. The more sun the more storms. The strongest cells may be capable of small hail, gusty winds and heavy rainfall. A few models do not bring the shortwave overhead until Monday morning therefore showers could stick around through out the day. Another shortwave trough could come in from the west bringing the next chance for precipitation. As of the now the timing is uncertain and overall it looks to be a quick wave. The long term will be comprised of temperatures near normal to slightly below normal due to the wave activity.
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.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 525 AM MDT Sat Sep 27 2025
VFR condition are prevailing attm and this should continue over through the day at most TAF sites with mid and high level cloudiness moving through. Showers and thunderstorms will be most prevalent over the south where KTEX and KDRO may be impacted by gusty winds and low probability MVFR conditions this afternoon. Shower and isolated thunderstorms lift farther north through the evening and overnight with PROB30 in many TAF forecasts. VFR should remain the prevailing condition at most TAF sites however the higher terrain of the central and southern zones are likely to be obscured at times in clouds.
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.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None. UT...None.
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SHORT TERM...15 LONG TERM...KJS AVIATION...TGJT
NWS GJT Office Area Forecast Discussion