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Area forecast discussion 
National Weather Service Sioux Falls South Dakota
252 am CST Friday Mar 6 2015

Short term...(today and tonight)
issued at 252 am CST Friday Mar 6 2015

Main challenge today is forecast highs. A mild flow of westerly
surface wind will dominate...and some middle level cloudiness will
likely pass through from west to east. 925mb temperatures are warmer
than yesterdays highs and we have lost snow cover over our entire
southwest quarter of the forecast area. Yesterday...the European model (ecmwf) MOS
guidance being warmer proved the best across locations that had
little to no snow cover. The trend looks similar to today...
especially noting a west wind is in store. Therefore favored the
European model (ecmwf) MOS guidance where snow cover does not exist. Where snow cover
still exists across the Highway 14 corridor and locations east of
Interstate 29...favored more of the American MOS guidance blends to
keep highs in those locations in the middle 30s to lower 40s. But where
areas our snow free...see no reason why middle 40s to middle 50s should
not pan out. One note about surface winds...not much of a gradient
exists but winds are a bit brisk in the mixed layer...so would not
be surprised if 10 to 20 miles per hour winds prevail in the afternoon hours.

Tonight...a short wave moves southeastward down the northwest flow
aloft. Middle clouds once again move into the forecast area...
especially throughout the northern half. In addition...all models
have now backed off the stratus behind the accompanying cold front
to our northern zones and moving in very late tonight. With a lack
of ascent and the stratus depth looking a bit shallow in our
north...for better or worse decided to not keep the mention of
patchy freezing drizzle in our northeast zones late tonight. However
would not totally rule out a sprinkle or freezing sprinkle in our
north under the middle clouds. But the potential for that looks a bit
weak at this time. Previous lows still look on target with
widespread middle 20s to lower 30s.



Long term...(saturday through thursday)
issued at 252 am CST Friday Mar 6 2015

Between minor cool intrusions over the weekend...we have a short
wave pushing through Saturday night with not much dynamic support
but decent thermal banding developing in prime position over the
southern end of the area. Have kept the light snow chance north and
east at a very modest level...30 percent maximum...because of the wimpy
dynamic support. There is also the question of position of any light
snow bands. For now have elected to keep the threat over the
northeast half of the area though models especially the GFS hint at
a further south track. The questionable nature of precipitation
production is the key...for a higher threat would probably slip the
maximum probability of precipitation south a bit...but whatever dynamic support there is seems
to be to the north. Will continue to end the mention by Sunday
morning though will keep probability of precipitation at decent non mention levels far east
for that time period.

The forecast for Saturday and Sunday daytime will be dry. Cloud cover
will be variable Saturday with low clouds in the cool push
decreasing during the late morning and afternoon while higher
clouds increase late Saturday ahead of the Saturday night wave.
Sunday cloud cover should decrease steadily. Temperatures both days
will be above normal with highs in the upper 30s northeast to 50
plus southwest.

Am going with the extended guidance idea of a dry and very mild
Monday through Thursday. This means ignoring the 00z GFS which seems
to be an outlier with its cool push Tuesday...an obvious response to
its handling of a very strong Canadian wave digging toward the upper
Great Lakes. The ec is much more modest on this and the Canadian/Gem
does not really have it at all. All this means daytime temperatures
mostly in the 50s and 60s...which is not too violently warm compared
to the warming that can happen this time of year...in fact if the
very mild pattern remains undented...some 70 plus highs west during
midweek would not be out of the question. Even the GFS brings upper
ridging back pretty quickly after its cool intrusion.



&&

Aviation...(for the 06z tafs through 06z Friday evening)
issued at 1052 PM CST Thursday Mar 5 2015

VFR conditions expected through the period.



&&

Fsd watches/warnings/advisories...
South Dakota...none.
Minnesota...none.
Iowa...none.
NE...none.
&&

$$

Short term...mj
long term...
aviation...chenard

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