364 FXUS63 KBIS 180827 AFDBISArea Forecast Discussion National Weather Service Bismarck ND 327 AM CDT Thu Sep 18 2025
.KEY MESSAGES...
- Showers, along with a few rumbles of thunder, remain in the forecast through Friday. The highest rain chances are today over south central and southeastern parts of the state. The highest chances tonight and Friday will be along and east of the Highway 83 corridor.
- Severe weather is not expected, though periods of heavy rain may bring some localized minor flooding at times.
- High temperatures will be mainly in the 50s and 60s today and Friday, then warming into the 70s and low 80s by Sunday. Low temperatures will be in the 40s to mid 50s.
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.DISCUSSION... Issued at 327 AM CDT Thu Sep 18 2025
Quasi-stationary low pressure system is currently, and will remain, centered over South Dakota today, before very slowly meandering northward tonight and through the day Friday. As a result, expect widespread rain showers to continue today through tonight, especially for south central and eastern North Dakota. Showers will then push northward before gradually ending from west to east on Friday, though may linger in the Turtle Mountains and eastern ND into Saturday. A few rumbles of thunder are possible today, mainly in far south central and southeastern portions of the state. Though a few rumbles are also possible in western ND. Severe weather is not expected, though localized minor flooding is possible if moderate to heavy rain (thunderstorms) remains over one place for an extended period.
Once this system clears out, mostly dry conditions are expected through the middle of next week. The one exception is late this weekend and into Monday when a passing shortwave may produce a few showers. Fortunately, the NBM has finally latched onto this idea and put mentionable PoPs into the forecast.
Due to widespread rain showers and cloud cover, highs today will be mostly in the upper 50s to low 60s, and mostly in the 60s on Friday. A warming trend is then expected this weekend as a thermal ridge passes through, bringing highs into the mid 70s to low 80s by Sunday. The aforementioned shortwave Monday favors cooler highs back into the mid 60s to low 70s. Beyond Monday, uncertainty remains in whether ridging will prevail, or if flow aloft will be more zonal or northwesterly. The NBM favors a seasonable temperature outcome with highs mostly in the upper 60s to low 70s. Lows through the next week are also favored to be seasonable to seasonably warm and in the 40s (seasonable) to low 50s (seasonably warm).
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.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1253 AM CDT Thu Sep 18 2025
Showers are expected to continue across much of the state through the period, while ceilings will lower to MVFR/IFR levels. An occasional rumble of thunder is possible, though confidence of lightning at any terminal at any time is very low. Or in other words, every terminal is far less likely than likely to experience a thunderstorm. Patchy fog may develop in northwestern and far southwestern ND tonight into early Thursday morning. However, this is highly dependent upon cloud cover and shower progression.
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.BIS WATCHES/WARNINGS/ADVISORIES... None.
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DISCUSSION...Telken AVIATION...Telken
NWS BIS Office Area Forecast Discussion