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Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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360 FXUS63 KFGF 201730 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1230 PM CDT Sat Jul 20 2024 .KEY MESSAGES... - Daily shower and thunderstorm chances through the period. Severe weather unlikely. && .UPDATE... Issued at 1220 PM CDT Sat Jul 20 2024 Signs of convection are starting to present itself over the Lake of the Woods area. Biggest uncertainty is still the timing of thunderstorm activity with this thick layer of smoke aloft. Latest report was from the grand forks airport that had the smoke up to 5000ft. However thoughts are still thinking thunderstorm development to start around 21z at the earliest. UPDATE Issued at 1013 AM CDT Sat Jul 20 2024 Morning light on visible satellite reveals widespread, thick smoke aloft around much of the Northern Plains and southern Canada. Weak winds aloft keeps confidence high in this smoke will linger through the day. This will have an influence on our daytime temperatures by slowing diurnal heating and tampering maximum temperatures some. During this update, leaning on CAMs that include affects from smoke like HRRR/RAP, both of which still reach convective temperatures progged to be around 85 this afternoon. However, these guidance start thunderstorm development later than some other guidance, likely owing to the influence of smoke. Adjusted PoPs a bit to delay the start of isolated to scattered thunderstorms into the 3pm-5pm timeframe, ending between 8pm-10pm. The exception to this may be in lakes country of west-central Minnesota where smoke is thinnest leading to earlier initiation of storms. Lack of shear today coupled with marginal but sufficient instability (MLCAPE 1000-2000 J/kg) lends high confidence in today`s storms being unorganized, pulse-type thunderstorms depositing outflow boundaries that kick off subsequent thunderstorms. Main hazards from this type of activity will be lightning and gusts 40-50 mph in relatively stronger storms. UPDATE Issued at 625 AM CDT Sat Jul 20 2024 Mostly quiet weather prevails this morning across much of the area, with only isolated shower activity in west-central Minnesota. Temperatures are generally in the low to middle 60s with light and variable winds. && .DISCUSSION... Issued at 253 AM CDT Sat Jul 20 2024 ...Synopsis... Current water vapor imagery nicely showing an upper level trough over the intersection of Minnesota, South Dakota, and North Dakota. Satellite shows some clouds over the FA, High confidence in lack of shear to organize thunderstorms puts confidence high in expecting thunderstorms to be mainly in the southern Red River Valley and MN Lakes country associated with this low. Northwest flow is here to stay for the majority of the forecast period, flattening to more westerly to end the week. Temperatures will be in the 80s through the work week, possibly warming into the low 90s as the UL ridge gets compressed before flattening. ...Daily Precipitation Chances... With the northwest flow, shortwaves are increasingly common in the mid levels. These shortwaves will bring numerous rounds of precipitation chances through mid-week, with shower and thunderstorm chances somewhere in the FA every day between now and then. With most of these, moisture is lacking to even get a quarter of an inch. However, Monday into Tuesday morning, WSUP Probabilities are 20 - 30% around the international border for greater than or equal to a quarter inch of precipitation. With these precipitation chances, severe chances are very low (less than 5%) with any of these weak systems that transit the area. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1220 PM CDT Sat Jul 20 2024 VFR conditions throughout the TAF period with the exception of vicinity thunderstorms. Looking at satellite the thick smoke aloft covers all the TAFS sites. According the latest PIREPs the smoke layer stops at 5000 ft so that is represented in the TAFS as the SCT layer. The smoke layer may also delay thunderstorm development to create more uncertainty but still thinking after 21z scattered thunderstorms may pop up until 0300 to 06z. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...CJ DISCUSSION...AH AVIATION...MM