Storm totals from the storm that impacted the NDAWN mesonet stations from May 9-11 is presented below.
In the next 48 hours there will be two disturbances (voracity maxes) will move across North Dakota. The first disturbance in association with increased lift in the atmosphere associated with a push of warm air (Warm Air Advection) will bring a band of rain from southwest to northeast across the state. Amounts will be fairly minimum with totals expected in the 0.25 inches or less category.
Another disturbance will follow on Thursday. The rain on Thursday will be associated with a surface low and stronger upper-air support than the wave that will move through tomorrow. It appears much (not all) of the rain form the Thursday event will bypass North Dakota to the south. A sub voracity maximum on the northwestern corridor of the main event will bring some rainfall into the eastern part of North Dakota. The moisture in Minnesota will likely exceed 0.75 inches in localized areas were thunderstorms will occur, yet, in North Dakota in the cooler sector will just a lighter rainfall, totals again in most locations will stay under 0.25 inches
A much more widespread rain (snow?) event will move into the upper Midwest and the Northern Plains on Sunday and Monday (May 17/18). It will be in many ways similar to the event of this past Sunday/Monday (May 10, 11) but perhaps a bit farther north. If the northern track is taken as expected, it would mean more heavier rain in the northern tier of North Dakota than what occurred with the previous event, plus, bring a threat of severe weather into at least the southern portions of North Dakota. Although still several days out, the storm should have similar potential for rain amounts as the Mother’s Day Storm, just the specifics as to where the heavier snow bands will set up is always the question this far out.
After the May 17-18 event, there still appears to be a frost threat on the mornings of May 19 and 20. This was the frost event mentioned in a late April blog posting. One (or both) of those mornings may be similar to what occurred this morning. One advantage to the coolness in that time period is the additional low level moisture associated with wetter soil conditions helps keep the temperatures warmer than the drier soils we had previous to these rain events.
After May 20, at least near normal temperatures (65 to 75) is expected with yet another possible strong storm around May 25/26 time frame. Although the animation below goes through quickly (pauses on Day 10, May 22), the idea of below normal 500 mb heights in the southwestern part of the United States, is a strong indication of continued southwesterly upper level wind flow into North Dakota, which is by far our wettest pattern. Therefore another storm near Memorial Day with severe weather in the plains is expected. This will leave our extended drier period followed by a wet May for much of North Dakota.
Current thinking is that this wet flow will break down for a while after Memorial Day and therefore in early June the region will move back into an above average temperature/drier pattern.
Daryl Ritchison