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Area forecast discussion 
National Weather Service Omaha/valley NE
1142 am CST Tuesday Dec 1 2015

issued at 1132 am CST Tuesday Dec 1 2015

Have updated the forecast to increase probability of precipitation today across the
northern half of the County Warning Area. The 12z koax sounding indicated a fairly
deep thermal layer in the dendritic growth zone. This along with a
couple areas of 700-300 mb DPVA rotating through the County Warning Area should
provide periods of -sn over the northern County Warning Area through the
afternoon. Not expecting a sig accumulation...but periods of -sn
seemed like a sure thing and so increased probability of precipitation. Still have 1-2
inches of new snowfall indicated in the Highway 20 corridor.
Another band of lift will rotate southward tonight toward the County Warning Area and
may provide one last shot of -sn to a good part of the area
/except the southwest/ tonight...and we will look at this further
for the afternoon update. Other elements of the forecast seemed on
track and few other changes were made.


Short term...(today through thursday)
issued at 302 am CST Tuesday Dec 1 2015

With large upper low spinning over the central US today...flurries
and light snow will linger. Subjective 00z upper air analysis
indicates upper low centered in Nebraska/southern South Dakota...with 500mb height
falls up to 190m at koma. Upper-level jet was punching across the
southern US...with 150kt winds in southern AZ/nm. Low at 850mb was
centered in northeast Nebraska/southeast South Dakota...with strongest temperature
gradient across eastern to central Iowa and northern to western MO. An
850mb cold air pocket was noted from the MO River Valley west toward
Idaho/Washington associated with the upper low. Surface low at 08z was centered
in southwest Minnesota/southeast South Dakota...with surface cold front still west of
the County Warning Area...from northeast to south central Nebraska.

Main forecast concern is lingering light snow associated with the
large upper low. As low ejects eastward...County Warning Area will be in the
cyclonic flow behind the low...with a few ripples in the flow to aid
development/persistence of light snow. With a deep dendritic growth
zone in forecast soundings...the lingering low should be fairly
efficient in producing light snow. Have increased probability of precipitation tonight to
account for system lingering just a little longer...and lift
persisting into this evening and overnight. Additional snow amounts
of a few tenths to around an inch through tonight are
possible...with no accumulation expected roughly south of a line
from David City to Bellevue to Red Oak and with the higher
accumulations close to the Nebraska/South Dakota border.

Under cold air advection on Wednesday...temperatures will remain on
the cold side. Upper low will continue to slide eastward and
open...with rising heights across the central US. Low-level flow
will turn southwesterly...with dry conditions across the central
US...and temperatures will begin a moderating trend on Thursday.

Long term...(thursday night through monday)
issued at 302 am CST Tuesday Dec 1 2015

Dry weather is expected through the rest of the forecast. Upper-
level ridge will slide across the MO River Valley by late
week...with southwesterly low- to middle-level winds aiding
moderating trend. Have nudged temperatures upward for middle to late
week...especially given lack of snowpack in the southern County Warning Area...but
think forecast temperatures may still not be quite warm enough. European model (ecmwf)/GFS
both indicate another upper low traversing the Southern Plains by
Sunday/Monday...but precipitation is currently prognosticated to stay
south of the County Warning Area as the low bowls across the plains.


Aviation...(18z tafs for kofk...klnk and koma.)
Issued at 1132 am CST Tuesday Dec 1 2015

The cyclonic flow around the low over eastern South Dakota will continue to bring
periods of -sn to the tafs over the next 18 hours. During these
periods we will see MVFR to IFR visby and along with the
widespread MVFR ceilings...some IFR as well. Along with the occasional
flurries through the day we expect a better batch of -sn to move
through the taf sites from late evening at kofk...and at koma/klnk
after 06z. Conditions will improve late tonight with VFR
conditions into the day on Wednesday.


Oax watches/warnings/advisories...



short term...Mayes
long term...Mayes

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