Severe threat tomorrow
I wrote about tomorrow's impending storm yesterday (see Related links article) and most of that forecast still looks valid. Only change is the threat for severe weather tomorrow afternoon is increasing in eastern Nebraska. The SPC now has most of the eastern sixth of the state in the slight risk category with the marginal risk extending out to O'Neill and Holdrege. The high-resolution models are getting a bit more bullish on thunderstorms developing in the eastern third of the state after 1:00. Supercell development with hail would be possible east of Highway 77. The good news is the threat will be relatively short-lived but the bad news is that threat may still be there in the Omaha and Lincoln metro areas during rush hour. Best chance of seeing tornadoes tomorrow will be in eastern Iowa and Illinois. Areas to our south have elevated to critical levels of fire danger.
Figure 1. SPC outlook for tomorrow
Warm and sunny
Sunday will feature warmer temperatures and lighter winds than Saturday and things look very nice for St. Patrick's Day. A ridge will be sitting over us (Fig. 2) during the day and this will bring ample sunshine and warm temperatures. Highs likely to be in the 70's statewide with temperatures at or slightly above 80°F possible across south central and southeast Nebraska.
Figure 2. 500-mb height anomalies on Monday
Figure 3. Projected high temperatures on Monday
Winds will be a bit elevated on Monday in the northwestern quadrant of the state Nebraska, so there will be some fire danger risk between Valentine and Chadron. Elsewhere winds will be lighter. Perfect day for playing hooky from work and golfing or enjoying a green beverage on a patio!
Snow?
Mother Nature has a sense of humor and wants to keep us on our toes so the warm weather isn't going to last. A front will be moving through the state on Tuesday, bringing sharply colder temperatures compared to Monday for the western and northern halves of the state. The southeast quadrant should enjoy another warm day in the 70's but temperatures may drop quickly in the afternoon if the front is a little speedier than currently forecast.
Figure 4. 500-mb height anomalies on Wednesday morning
As we move into Tuesday night, another trough will be moving into the Central Plains and this will help generate the rising motion needed to produce precipitation across the state. There is still some uncertainty as to the exact path and strength of the storm system. But there is a good chance of moisture statewide starting Tuesday night in western Nebraska and during the day Wednesday in the eastern half of the state. Current indications are that there will be sufficient cold air and dynamics for a rain to snow scenario for basically the entire state, with 1-3" of snow likely for the whole state and areas from Hastings to Omaha having the best chance at more than 4".
Figure 5. Probability of 3" according to the ECMWF ensemble
The ECMWF AI model has been more aggressive on moisture return and shows a better chance of 0.5-1.0" of total moisture across eastern Nebraska, with some falling as rain initially followed by 4-6" of snow. Wind speeds are also likely to be in the 15-25 mph range from the north and northwest, so visibility may be an issue, especially on east-west roads if snow does indeed come to fruition. It is quite possible that roadway accumulation will be minimal in the eastern half of the state due to falling on warmer ground and during the daytime hours. Nevertheless, it will be a raw and cold day on Wednesday with temperatures likely not getting out of the 30's in eastern Nebraska and only getting to 40-45°F in central and western Nebraska.
Mild weather returns. More precipitation next weekend?
Temperatures should moderate later next week and the CPC favors warmer than average in the period from March 20-26th. But we may be done with the exceptionally warm temperatures for a little while after Monday. Additional precipitation is also possible next weekend as another storm system moves into the Central Plains. That would most likely be all rain and it is possible that the northern third of the state misses out on precipitation.
Figure 6. CPC 8-14 day temperature outlook
Figure 7. CPC 8-14 day precipitation outlook
Drought update
Precipitation last week did improve soil moisture percentiles a bit across northeast Nebraska and portions of the Sand Hills. But most of the state is still under the 30th percentile for soil moisture in the top 1-meter of soil. Thus, any and all moisture that falls over the next few weeks will certainly be welcome as soil moisture is still quite short across much of the state and the broader region in general.
Figure 8. Soil moisture percentiles from NASA SPoRT LIS
The latest Drought Monitor shows some improvement in the Sand Hills from severe (D2) to moderate (D1) drought from western Rock and Cherry County down into McPherson and Logan counties. There was a small area of degradation from abnormal dryness (D0) to moderate drought (D1) in Deuel and Keith counties. 91 percent of the state is in some form of drought, up slightly from last week. It is possible enough precipitation may fall over the next 10 days to bring improvement in drought status in parts of eastern Nebraska.
Figure 9. Latest U.S. Drought Monitor
