Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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611 FXUS63 KFGF 192011 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 311 PM CDT Wed Jun 19 2024 .KEY MESSAGES... - Additional chances for thunderstorms and heavy rain are possible late Thursday through Saturday. - Active weather continues early next week, with another chance for showers and possibly strong thunderstorms Monday and Tuesday.&& .DISCUSSION... Issued at 310 PM CDT Wed Jun 19 2024 ...Synopsis... The high pressure system has remained over Central North Dakota today relatively suppressing any cumulus development closest to the low. However, low level cumulus has gradually increased east of the Red River where more low level moisture was trapped under the high pressure system meandering through our area. This area of high pressure will slowly move off to the east tonight as a 700mb moves through the northern plains and increases brief precipitation chances for areas south of I-94. CAM soundings show the lower levels drying out by this evening so its uncertain if these light showers will reach the ground or remain as virga. Thursday afternoon into the evening a warm front will produce more Thunderstorm chances for the area. The axis of development for this precipitation event looks to be lighter for our area than past events. Precipitation totals looks to to be between 0.5 to an inch by the South Dakota Border, and less than 0.25 inches North of the I- 94 corridor. MUCAPE ahead of the shortwave could be upwards of 2000 J/Kg according to model soundings, which could support a mention of isolated strong to severe thunderstorms, which would likely be elevated due to the overall lack of surface based instability. Shear in both the 0-3Km and 0-6Km layers are supportive of large hail and damaging wind gusts. Friday through Wednesday: Continued warm air advection and a low level jet in conjunction with a shortwave will provide forcing for elevated convection Friday night. At the nose of the low level jet in the far southern FA, CAPE values Friday evening into the overnight are around 1000 J/Kg with favorable shear. Therefore, the main hazards would be large hail and damaging winds. Due to the elevated nature of the storms, the tornado risk is very low. Currently, the better instability is progged to reside south of the area. Therefore, the SPC has placed our extremely far southern FA under a marginal (level 1 of 5) risk. This threat appears conditional on the track of the surface low. If the low tracks further south, the best instability may stay entirely south of our area. Further north, the chance for at least a few isolated elevated severe thunderstorms increases. Heavy rain however will remain a threat with any thunderstorm that develops. While not stationary, storms will travel slowly, resulting in the potential for locally heavy rain. Probabilities of at least an inch of rain are 80% in the southern Red River Valley into west central MN. Probabilities drop quickly to the north. As we work into next week, a progressive pattern will set up over the region. Several shortwaves are expected to propagate through. The first wave arrives Monday, providing a chance for severe thunderstorms. Shear vectors are favorable for discrete storms. Probabilities Monday afternoon of CAPE values of at least 2000 J/Kg are 70% across our southern counties. The fine details that will determine the eventual setup for severe weather such as the orientation of the wave and exact timing are too far out to determine. However it will be a period worth monitoring for strong to severe weather. This active pattern will continue beyond Monday as more waves propagate through the region, with models currently having a poor handle over each waves specific strength and timing. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1244 PM CDT Wed Jun 19 2024 A low level cumulus field is the main reason for the VFR/MVFR conditions at all TAFs site except KDVL which is expected to remain relatively clear because its closest to the surface high. Around 06z to 09z some brief showers will move from the south ahead of the warm front however, there is some uncertainty on how far north these showers will move and may reach KFAR. By 12z these showers will move East and may move over KBJI. VCSH was placed in the TAFS to account for this uncertainty. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ DISCUSSION...MM/Rafferty AVIATION...MM