Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service North Platte NE
258 PM CST Thursday Mar 5 2015

issued at 258 PM CST Thursday Mar 5 2015

At 19z water vapor imagery showed a deep trough extending from
eastern Canada down into the lower Mississippi River valley with
ridging across the West Coast. The northern and Central Plains Sat
in northwest flow between these two features...where a weak
shortwave trough was seen over western South Dakota. Further
upstream multiple upper level shortwave troughs were moving over the
ridge in the Gulf of Alaska and northern Pacific. A warm front was
being pushed east across Nebraska today by the shortwave trough over
South Dakota. This was bringing warmer air aloft and with downslope
westerly winds...the boundary layer was mixing well across western
Nebraska...with some areas seeing mixing to 750mb. This brought
warming into the middle and upper 40s for much of the area.


Short term...(this evening through friday)
issued at 258 PM CST Thursday Mar 5 2015

The upper level shortwave over South Dakota will move southeast
across Nebraska tonight and be into Illinois by 12z Friday. This
will spread the warmer airmass across the entire forecast
area...with 850mb temperatures rising above 0c in all areas. Lows
tonight are expected to be warmer than the past few nights due to
the warmer air...however with a weak pressure gradient winds will
diminish as the boundary layer decouples. There may be some
clouds...but not more than scattered coverage so anticipating good
radiational cooling for most areas which will still drop lows into
the teens in some locations.

Then for Friday...the airmass continues to warm...with 850mb
temperatures increasing further...ranging from around 2c to 5c
across the forecast area. Skies should be mostly sunny as the models
are showing little moisture over the area as most of the cloud cover
moving over the ridge in southwest Canada will pass across the
Dakotas as the ridge begins to broaden causing more westerly flow
than northerly flow locally. The low level flow will also be
westerly...bringing some downslope effect to the area. The
combination of good sunshine...downslope flow...decent mixing and a
warming layer looking for temperatures to rise into the upper 40s to
upper 50s.

Long term...(friday night through thursday)
issued at 258 PM CST Thursday Mar 5 2015

Saturday highs will continue to be mild in the near 60 in
the southwest. A weak Pacific cold front will bring an increase
of clouds overnight. Temperatures drop off slightly behind the
front for Sunday...for highs of 50 to 55.

For Monday through Thursday...the upper ridge along the West Coast
on Sunday will flatten out and progress eastward Tuesday and
Wednesday. Highs into lower 60s Monday to warm further into the
middle and upper 60s Tuesday and Wednesday. Highs near 70 look
attainable across south each day.

By Thursday...a backdoor cold front remains forecast by the
GFS...while the European model (ecmwf) keep mild temperatures across the region.
Prefer the warmer European model (ecmwf) solution. Going highs to range from near
65 far south to the lower 50s nctrl. Model differences in the
medium range are not unusual for this time of year...although do
expect better agreement in the next few days. Regardless of
synoptic differences...dry conditions are forecast to persist.


Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 1225 PM CST Thursday Mar 5 2015

A warm front was moving across western Nebraska
Thursday...switching winds to the west. The westerly winds will
persist through Friday afternoon. Wind speeds will be light
tonight then may increase late Friday morning as the boundary
layer mixes. However...not expecting winds over 20kts. Cloud cover
will be intermittent over the next 24 hours...and remain VFR.


Lbf watches/warnings/advisories...


short term...Brooks
long term...roberg

National Weather Service Glossary of Abbreviations