Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Omaha/valley NE
624 PM CDT Thursday Mar 26 2015

Short term...(tonight through sunday)
issued at 304 PM CDT Thursday Mar 26 2015

Active and cooler pattern is in place across the Continental U.S.. subjective
12z upper air analysis indicates 500mb trough digging into the Great
Lakes...with rising 500mb heights in the west. Water vapor imagery
indicated a shortwave embedded behind the digging upper trough
making its way through the Dakotas toward Nebraska. 850mb analysis
indicated a low in western ont...with a cold front across Minnesota/central
Nebraska toward nm...and with colder 850mb temperatures around -5 to -10c
spilling into the Dakotas/MN. Precipitation /some rain and some
snow/ had spread into northeast to north central Nebraska.

Main forecast concerns are potential for light precipitation tonight
and again tomorrow night...before milder weather returns.
Temperatures are cooling in association with precipitation...with light
rain able to turn to light snow based on webcams...but with little
accumulation noted so far. Have kept mainly rain mention for
southern County Warning Area temperatures are near 50f right now and
would have to fall a ways for snow...and think precipitation will largely
be out of the County Warning Area by around 03z. Once precipitation exits...the rest of the
night will be dry and cool as high pressure slides through the area.

Next shortwave trough in the stream should slide through the area
tomorrow afternoon and evening. A sharp thermal gradient will
remain across the County Warning Area as upper-level trough continues to dig into
the east and ridging builds to the west. Have nudged maximum temperatures
downward given weak mixing and cold middle-level temperatures. After
skirting into northeast Nebraska in the afternoon...precipitation should follow
a relatively narrow axis roughly aligned with the MO river by around
00z Saturday...sliding east of the river through 12z Saturday and
out of the area. With evening and overnight timing...and colder
850mb temperatures...precipitation type should incline more toward snow
after an early rain/snow mix potential...but accumulations should
remain light and should be limited to along/east of the MO river.

On Saturday...warm air advection commences across the MO River
Valley as the eastern trough slides eastward and upper-level ridging
nudges into the area. With southwesterly 850mb winds and
south/southeasterly surface winds...temperatures should recover
quickly...especially in the western County Warning Area...with a warming trend
continuing into Sunday.

Long term...(sunday night through thursday)
issued at 304 PM CDT Thursday Mar 26 2015

Milder weather will continue through Tuesday...with temperatures
reaching the 70s both Monday and Tuesday across the area. Will need
to keep an eye on those days for fire potential...but will remain benign. By Wednesday...a cold front
is forecast to move across the area as an upper-level shortwave
crosses the northern plains. GFS is slower with the front and more
aggressive with precipitation than the European model (ecmwf)...with the Gem falling
between the two. Cannot rule out thunder with the frontal
passage...but with so much uncertainty in timing
precipitation...will hold off on mention for now and just include
showers on Wednesday until consistency is better established. The
cold front does not appear to bring significantly colder surface
temperatures behind it...and have kept temperatures above normal
/though less so/ for Wednesday and Thursday.


Aviation...(00z tafs for kofk...klnk and koma.)
Issued at 621 PM CDT Thursday Mar 26 2015

Band of rain and snow moving southeast through eastern Nebraska
will bring IFR ceilings and MVFR visibilities to all taf sites through about
04z before improving conditions are expected. Ceilings should lift to
VFR by 06z most areas with unlimited visibilities. However there is a
slight chance for IFR fog to develop near 12z. Otherwise north
winds will turn to the south between 15z and 21z...but speeds
should remain under 12kt for the most part.


Oax watches/warnings/advisories...


Short term...Mayes
long term...Mayes

National Weather Service Glossary of Abbreviations