Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Hastings NE
1138 am CST Monday Nov 24 2014
Short term...(today and tonight)
issued at 529 am CST Monday Nov 24 2014
..NW winds gust 35-40 miles per hour with isolated g45 with diminishing
clouds in mostly colder than normal temperatures...
Aloft: the newly reestablished longwave trough axis was shifting east
of the forecast area. Back to northwest flow through tonight. The next shortwave
trough to affect the forecast area was over British Columbia. This trough
will pass through here tonight with only an increase in high clouds.
Surface: the forecast area was in the cold sector of deep low pressure
over the Great Lakes this morning. We will remain in the cold
sector through tonight. Western USA high pressure will gradually build in
with cyclonic boundary layer flow becoming anticyclonic. Its ridge
axis will pass through after midnight. A clipper will form over western
Canada tonight and an associated warm front will develop southward
into the region.
529 am: lots of wrap around clouds in cyclonic northwest flow...north and east
of the Tri-Cities. Still cant rule out a stray flurry although
have not seen any in regional observation recently.
Bbw measured a g39 kts at 421 am. That is indicative of what our
maximum wind potential is today once convective mixing commences.
Today: continued windy. Northwest winds will gust 30-35 kts in downward
Transfer as the boundary layer becomes unstable. Potential peak
gusts as high as 40 kts per BUFKIT mixing algorithm. Used GFS
with its deeper mixing.
The rap/NAM/GFS agree the western fringe of the wrap-around clouds
will gradually shift east of the forecast area leaving skies sunny.
Simulated infrared imagery from the 4 km NAM nest suggests some patches
of cirrostratus will begin moving in from the northwest late and this
is reasonable based on current satellite...with the northern rockies
shortwave trough diving to our west.
Internal verification shows we have been running too cool on high
temperatures recently. So used 06z rap to nudge temperatures upward slightly.
Highs will still be 5-10f colder than normal for most of the forecast
Tonight: winds drop off early evening with decoupling. Patches of
cirrostratus continue to drift through but should be no worse than
Used the weighted consensus of the 3 best-verifying temperature guides
for lows...which favored the colder MOS temperatures. Just slightly
colder than normal.
Long term...(tuesday through sunday)
issued at 407 am CST Monday Nov 24 2014
The big Holiday weekend is fast approaching and no travel
problems are expected across Nebraska and Kansas. Always remember
you can check www.Weather.Gov for the latest weather conditions
and forecast for anywhere in the country where you might be
traveling to this Holiday weekend.
The biggest concern for our area during the Holiday weekend will
center around several big temperature swings.
Tuesday...this should be a warmer day with lighter winds. The
strong northwest wind of Sunday and Monday will give way to a more
gentle southwesterly breeze that will help to warm highs into the
middle and upper 40s across most Nebraska zones to the lower 50s
across portions of northern Kansas. There are some model
differences with the 00z GFS trying to bring the next cold front
into Nebraska zones by Tuesday afternoon along with some sprinkles
and slightly cooler air. However...the 00z NAM and 00z GFS are
both slower with the cold front and are dry. This forecast leans
towards the European model (ecmwf)/NAM solution.
Tuesday night into Wednesday...cooler air will filter into our
region behind a cold front. We can not rule out a flurry or
two...but given most forecast models are completely dry...we will
keep the forecast dry and withhold any flurries for now. Forecast
models are not as cold with this airmass as they were several days
ago and expect highs on Wednesday should still reach the upper 30s
across northeastern zones to the middle 40s over north central
Thanksgiving...unfortunately the Holiday itself appears to the be
coldest day of the weekend as the cooler air that settles in on
Wednesday may hang around through Thanksgiving day.
However...forecast models have been trending warmer and so would
not be surprised if our forecast highs on Thanksgiving day
eventually get raised some. For now will continue to go with the
overall superblend of models...which results in highs in the middle
30s in the Tri-Cities...to the lower and middle 40s over northern
Friday through Sunday...the overall upper flow becomes more zonal
with the real cold air boxed up in Canada. This will also keep the
storm track well to our north resulting in continued dry
conditions. There is good confidence in Friday being a very nice
day with highs likely around 50 in the Tri-Cities to the middle and
upper 50s over north central Kansas with just a light southwest
wind. Saturday is much more uncertain with a cold front on our
door step. The latest 00z European model (ecmwf) is slower with the cold front and
indicates that highs on Saturday may be even warmer than on Friday
possibly reaching into the 60s...but the 00z GFS is much quicker
with the cold front and would have temperatures falling through
the 30s Saturday afternoon. Our official forecast is currently
somewhere in the middle with a high degree of uncertainty at this
time. Confidence really does not improve much on Sunday as there
is uncertainty with regard to how cold the next air mass will be.
The 00z GFS and 00z European model (ecmwf) have both trended downward and would
result in highs only in the 20s on Sunday while our forecast still
is incorporating recent runs that were warmer and is calling for
highs in the 30s and 40s. Basically...expect forecast changes in
the coming days as the uncertainty issues get ironed out.
Aviation...(for the 18z kgri/kear tafs through 18z Tuesday afternoon)
issued at 1125 am CST Monday Nov 24 2014
Gusty northwest will be the main concern for the taf period
through the afternoon hours. Northwest winds of 20 to 25kts and
gusts of 30kts are forecast until the gradient relaxes this
evening. Cloud cover is expected to thicken toward Tuesday morning
and have kept ceilings at VFR.