Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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939 FXUS63 KFGF 281141 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 641 AM CDT Fri Jun 28 2024 .KEY MESSAGES... - There is a level 1 out of 5 risk for severe thunderstorms across the region today in the late afternoon and evening. - There is a low chance for severe thunderstorms again Monday across the region. && .UPDATE... Issued at 641 AM CDT Fri Jun 28 2024 Patchy fog has started forming this morning thanks last nights moisture. There are lingering showers slowly working its way out of northwest Minnesota. Expecting by this afternoon this fog to lift or dissipate as we are mixing out. The severe risk still seems very conditional and heavy rain showers or strong thunderstorms may still be the more likely scenario. && .DISCUSSION... Issued at 404 AM CDT Fri Jun 28 2024 ...Synopsis... The wave responsible for last nights showers is moving off to the east into the great lakes region. The upper level low is currently on the border of Alberta,Canada and Montana. Convective guidance shows the low moving directly over the Northern Plains and then exiting the region via the arrowhead before moving back into Canada over the great lakes. Starting this afternoon this low is depicted as entering North dakota from the West and having this narrow band of instability off the frontal boundary that extends into the valley. However, the moisture and theta-e axis is being pulled across the arrowhead potential leaving our area with very little to lift. Looking at model soundings our mixed layer Cape is around 500 joules which could lead to showers and some pretty lightning bolts but not really severe. However, the catch is the shear profile ahead of the low is about 30-40kts which is sufficient to sustain storms if convection were to initiate. With this upper low passing directly conceptually we can obtain more forcing and instability ahead of the low but I`m not quite to sure if we have a long enough destabilization period to help the dynamics produce more than heavy showers. The model soundings better support heavy rain but SPC did keep the marginal risk over the majority of that CWA because of the low passing through. Because of this going to message severe potential of quarter sized hail and 60 mph just because if we do reach a long enough destabilization period then we might hit severe but another round of heavy rain with lightning is probably more likely. ...Severe threat Monday.... Another mid/upper wave follows a very similar track and evolution as the system Friday, with a period of widespread showers or embedded thunderstorms. There is a signal for a deeper warm sector building into our region within most clusters, and higher probs for SB CAPE to exceed 1000 J/KG during the peak heating/diurnally favored period of the afternoon/evening. CSU GEFS based machine learning (15-30% severe probs) are supported by 100% chance for greater than 55 NBM CWASP and 50-60% probability for NBM CWASP values exceeding 65. That aligns with a threat for isolated to scattered severe convection. This is still farther out, so details/impacts are still inherently uncertain.&& .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1031 PM CDT Thu Jun 27 2024 MVFR to IFR and eventually LIFR conditions expected through tonight into Friday evening. With the TSRA moving through, ceilings are forecasted to drop to around 005 into Friday morning and remain there for the TAF period. Winds will lessen to around 10 knots, but before then they will be gusting up to 20 - 25kts and sustained around 15 kts. Winds will shift into Saturday morning, but that is outside the current TAF period. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 641 AM CDT Fri Jun 28 2024 Fog has moved into some of the TAF sites creating a mix between LIFR,IFR, and MVFR conditions. As we slowly start to mix out during the day the conditions should rise to MVFR/VFR by 18z. However by 23z KDVL could start to see some showers from the start of the next wave. By 03z the Red river valley would then start seeing those showers. KBJI may start seeing those showers by 06z. Ceilings are expected to drop back down into the Low MVFR/IFR category just ahead of those showers. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...MM DISCUSSION...MM AVIATION...MM