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Area forecast discussion 
National Weather Service Hastings NE
1155 am CST Wednesday Nov 25 2015

issued at 1148 am CST Wednesday Nov 25 2015

Dense fog has lifted and thus the dense fog advisory for portions
of the forecast area was allowed to expire.

Previous forecast for winter storm on Thanksgiving is still on
track. Will be considering an upgrade to a warning for portions
of the watch area later this afternoon. Coordination regarding
the type of warning and area is still ongoing. Some areas within
the watch may be transitioned into a Winter Weather Advisory.

Update issued at 535 am CST Wednesday Nov 25 2015

Dense fog has developed along the edge of a swath of low level
stratus across the region. Observation/webcams show reductions in a dense fog advisory has been issued through
middle morning.


Short term...(today and tonight)
issued at 411 am CST Wednesday Nov 25 2015

Quiet conditions currently in place across the area early this
morning...with upper level flow remaining slightly southwesterly ahead of
the main feature of area of low pressure spinning
over the or/NV/CA border region. At the surface...the County Warning Area is
primarily influenced by low pressure over the High Plains...but
its a weaker pattern...thus winds for most are on the lighter
side. As expected...satellite imagery shows a sizable swath of
increased lower level moisture/stratus stretching from southern Texas into
southern Minnesota. Have seen ceilings gradually drop across the eastern half
of the County Warning Area...with some variability in visibilities at a few
locations. Will continue to keep the mention of fog/dz in for this
morning. This has also resulted in quite a gradient in
3 am observation range from the middle 20s in the west/northwest to the middle to upper
40s in the southeast.

Short term hi-res models continue to show the potential for a
larger area of fog to develop early this morning...and if it
does...last through a good chunk of the first half of the day.
Kept that mention going...but will have to see how things actually
pan out in the next few hours.

Otherwise with the main focus of the approaching storm...overall
through today and tonight...there hasnt been any significant
changes looking at the general upper level pattern. Models
continue to show the main upper level low over the western Continental U.S.
Not making a lot of progress 12z Thursday it looks to
only have moved into the western Utah area. At the surface...still expecting
to see a cold frontal boundary sag south through the County Warning Area with
time...switching winds to the N/NE...though the colder air mass
isnt exactly speedy when building in behind. Larger scale lift is
expected to continue to gradually increase with time...especially this
evening and tonight. Will continue the mention of drizzle through
the daytime hours where models suggest the lower level stratus will
linger...with increasing probability of precipitation after 00z and the highest probability of precipitation lie
in the 09-12z period.

The main question has been...and continues to be...with
precipitation type. The timing of the colder air push aloft and at
the surface still look to be a bit offset from another. The quicker
push of colder air at the surface will keep that threat of freezing
precipitation in the forecast...mainly for the northwest half/two-thirds
of the County Warning Area...further southeast...there is better potential things will
remain liquid.

One forecast change was to go ahead and add valley and Dawson
counties to the Winter Weather Advisory /no changes were made to
times/ the threat for freezing precipitation causing travel concerns
is there...though that threat may not last as long as other areas
before it switches over to all snow.

Long term...(thursday through tuesday)
issued at 411 am CST Wednesday Nov 25 2015

A messy wintry mix of precipitation is still on track to impact
our region on Thanksgiving.

The weather on Thanksgiving remains complicated and messy due to a
variety of precipitation types in the form of freezing
drizzle/rain...sleet and snow expected which will result in
accumulations of some ice and light snow. All of this will likely
cause impacts for Thanksgiving Holiday travel.

Moisture will increase across the plains ahead of a potent low
pressure system in the Great Basin...while cold air infiltrates
the Central Plains behind a cold frontal boundary during the day
Thursday. The cold air will displace the warmer airmass with surface
temperatures steadying/falling during the day while warmer air
above the surface will produce a wintry mix of precipitation in the form of
freezing rain as those surface temperatures fall below freezing during the
day. As the cold air deepens with time...a transition to sleet and
snow is expected before ending. The better moisture and highest
precipitation amounts will occur across our southeast zones with the main
question being how much of this will fall as rain initially before
changing over to freezing rain and a wintry mix. The NAM/sref keep
surface temperatures above freezing in our southeast zones through 18z Thursday then
drop them below freezing in the afternoon...whereas the GFS/European model (ecmwf) drop
temperatures below freezing faster. Timing of the transition will impact
the rain vs freezing rain forecast and ice accumulations.
Regardless...surface temperatures will eventually fall below freezing leading
to the freezing/frozen transition. It is hard to argue with
current headlines for this event as ice and sleet accumulations
are expected...while overall snow accumulations will be lighter.
Just not ready to upgrade to a warning as surface temperatures will be key to
amount of accumulating ice in our southeast zones and this could
go either advisory or warning.

This round of precipitation winds down Thursday night into Friday
as the cold frontal boundary reaches the Southern Plains states
and a frigid 1042mb surface high pressure builds south onto the
plains. Some very light snow or flurries may linger across our far
southern zones into the first part of the day with little if any
accumulation expected. Temperatures will struggle in the cold
airmass with highs expected to generally remain below freezing and
those venturing out for black Friday should be prepared to bundle

Friday night through Monday the weather remains unsettled with
continued chances for light wintry precipitation in southwest flow
with the closed upper low pressure system in The Rockies through
at least Saturday. Models suggest the system or a part of the
system will begin to lift out onto the northern or Central Plains
Sunday into Monday...however models are not in good agreement on
this at this time with the operational GFS favoring a farther north track
than the GFS ensemble and the European model (ecmwf). Hard to tell at this point
and did not make a whole lot of changes given the uncertainty in
the track. Of note is that in this pattern...we will be in a
prolonged period of lift which will provide chances for light
precipitation through the weekend and possibly into Monday as
well. The farther north solution of the models brings the dry slot
across the plains and we lose dendritic moisture while the llvls
remain saturated. Precipitation type could be anything from
freezing drizzle/rain to sleet or snow depending on the track of
the system and thermal profile. Still plan to keep things simple
and go with snow for precipitation type but this will need to be monitored
closely especially once we get through the Thanksgiving wintry
event. Those traveling over the weekend for or
returning from the Holiday will need to monitor weather conditions
due to unsettled weather persisting through the weekend and early
next week.


Aviation...(for the 18z kgri/kear tafs through 18z Thursday afternoon)
issued at 1148 am CST Wednesday Nov 25 2015

The primary forecast concern will be the threat of freezing rain
and runway icing at both kear and kgri late Wednesday night after
midnight...but becoming more likely just before dawn on
Thanksgiving morning. A tenth of an inch of ice accumulation
followed by up to 1 inch of sleet and snow appears likely on
Thanksgiving day. Hazardous impacts to aviation are likely.
Ceilings will also be low.


Gid watches/warnings/advisories...
NE...Winter Storm Watch from late tonight through Thursday evening
for nez049-063-064-076-077-086-087.

Winter Weather Advisory from midnight tonight to 6 PM CST
Thursday for nez039>041-046>048-060>062-072>075-082>085.

Kansas...Winter Storm Watch from late tonight through Thursday evening
for ksz007-019.

Winter Weather Advisory from midnight tonight to 6 PM CST
Thursday for ksz005-006-017-018.



short term...adp
long term...Fay

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