Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Hastings NE
1152 PM CST Thursday Feb 26 2015
Short term...(this evening through friday)
issued at 335 PM CST Thursday Feb 26 2015
Quiet conditions in place across the region this afternoon...with
upper air/satellite data showing northwesterly flow in place as
ridging remains in place off the West Coast and troughing lingers
across the north central Continental U.S.. outside of some cumulus affecting far
NE/SW fringes of the County Warning Area...skies have been clear. At the
surface...the main player across the County Warning Area is high pressure...which
is currently centered near the NC Continental U.S./Canadian border. This
has kept winds out of the north...and they have been on the gusty
side...sustained speeds are around 15 miles per hour with gusts peaking
around 25 miles per hour. As expected...temperatures have been well below average
for this time of year...with 3 PM temperatures ranging from the middle teens
to middle 20s.
Through the rest of the short term period tonight/tomorrow...hasnt
been any significant changes with the models...still showing an
upper level shortwave disturbance pushing S/southeast through the region.
There is good agreement showing the better potential for
precipitation to remain barely off to the west/SW of the County Warning Area as we
get into the early morning/daytime hours tomorrow...so have kept
the forecast dry.
Expecting another cold night across the County Warning Area tonight...with that
surface high pressure system currently to the north/northwest expected to slide
south. By midnight models show the center of the high starting to
move in the northestern corner of the County Warning Area...and at 12z is centered over
the NE/Iowa border. Winds will taper off to light/variable if not
completely calm...especially across northern/eastern portion...and with not a lot
of cloud cover expected lows falling into the single digits below
zero are expected. The light winds are expected to keep wind chill
values from dropping below 15 degrees below zero. Further
SW...models showing a better potential for a few more clouds...and
with not sitting with the calm winds have their lows in the single
digits above zero.
Long term...(friday night through thursday)
issued at 335 PM CST Thursday Feb 26 2015
Main concerns will be regarding precipitation chances on and off
through the period and cold temperatures.
Moisture starts to spread north into the area Friday night. This
is ahead of an upper wave that affects the area Saturday and
Saturday night. Precipitation spreads into the area from the
southwest mainly Saturday morning. By Saturday afternoon and
evening the snow should increase with the best chances in the
southeast part of the forecast area. The wave continues to affect
the area Sunday...but by afternoon the snow should diminish or
even come to an end.
Not expecting a Big Break because the next upper wave starts
moving into the area Sunday night. Models have some fairly
significant differences with this system as it moves through the
area. As the upper wave moves into the area there is warm
advection and the temperatures at 850mb warm up. The GFS is much
warmer than the European model (ecmwf) with the temperatures at 850mb. Then later
Monday a cold front moves through and temperatures cool back down
again Monday night. Have kept snow for most locations Monday...but
put in a little mixed rain and snow in north central Kansas...then
back to snow Monday night as the colder air comes back in.
Temperatures will be a little warmer again and so there could be
some rain and snow mainly in the southeast.
Models continue with some differences for Tuesday night through
Wednesday night. The GFS continues to bring through an upper wave
which brings another chance for some light snow...but the European model (ecmwf)
has the precipitation moving out of the area Tuesday night as
the GFS moves the precipitation in. With the uncertainty in the
models...have kept some low probability of precipitation in through Wednesday night.
By Thursday the upper trough moves through the area and there is a
little warm advection. Temperatures will warm a little but still
expect below normal temperatures.
Aviation...(for the 06z kgri/kear tafs through 06z Friday night)
issued at 1152 PM CST Thursday Feb 26 2015
Rest of tonight: VFR sky clear. Light north winds will become southeast by dawn.
Fri: VFR with some high cirrostratus ceilings off to the S and west.
Some model guidance is suggesting middle-level ceilings around 13k feet...but
this may be overdone based on current satellite. S winds under 10
kts. Confidence: medium
Friday eve: VFR with high cirrostratus ceilings possible. S winds around
10 kts. Confidence: medium