Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Goodland Kansas
223 PM MST Wednesday Feb 10 2016
Short term...(this evening through thursday)
issued at 204 PM MST Wednesday Feb 10 2016
Warm temperatures have eaten into the snowpack today. Temperatures
today are warmer across the entire area with lower to middle 70s
in the far south where there is no snow to lower and middle 50s
over most of the rest of the area. This has allowed dewpoints to
stay rather high despite westerly winds. More guidance is showing
a front backdooring into the eastern portion of the area later
tonight into tomorrow morning.
This is will create a light upslope to light and variable wind
field...especially in the eastern half to two thirds. Latest
guidance and probabilities are now not only indicating a rather
high chance of stratus but also fog in the above mentioned area.
As a result have added patchy to areas of freezing fog from the
middle of tonight into middle morning tomorrow.
Have temperatures cooler per the latest guidance/overnight
forecaster reasoning. Depending on how fast the stratus and fog
burn off...that could significantly impact tomorrows maxes
especially in the eastern half. It is possible that those
temperatures will need to be lowered some more.
Long term...(thursday night through wednesday)
issued at 220 PM MST Wednesday Feb 10 2016
Thursday night-Saturday....a shortwave trough rotating through the
northern plains around the large scale upper low will kick a strong
cold front south through the central US with Arctic high pressure
sliding south into the Mississippi River valley. The western extent
of this cold front will move from the northeast to the southwest
into our County Warning Area Friday/Friday night. Latest model trends have this
front over the northeast half of our County Warning Area Friday afternoon with
possible stratus following the initial frontal passage which complicates high
temperatures Friday. Adjustments downward were made to account for these
trends...but I still may not be cool enough in the afternoon in
Best upper level forcing and middle-upper level moisture remains
north...however NAM/GFS continue to show a light quantitative precipitation forecast signal late
Friday night into Saturday morning. This appears to be associated
with a low level saturated layer correlating with isentropic ascent
immediately above the shallow cold Post frontal air mass. This
raises concerns for possible freezing drizzle development if it
is realized. Low level flow remains out of the east-southeast and
sref probabilities and NAM visible/bl relative humidity fields show potential for fog
development as early as Friday evening through midday Saturday. Bl
winds begin to increase late however and model soundings indicate
a shallow dry layer in line with increased near surface mixing.
This lowers confidence in fog...but at this point I didnt want to
rule it out if winds do not mix. I added patchy freezing
fog/freezing drizzle mention Friday night/Saturday morning as
coverage/occurrence is still a question mark.
Models show Lee trough redeveloping by Saturday morning with
southern flow supporting moderating temperatures aloft (particularly in
our west). NAM/sref are slow to clear low level clouds and
models currently keep stalled front over our County Warning Area. The result could
be a large spread in highs over our County Warning Area with better chance for
clearing in the far west.
Sunday-Wednesday...large scale ridging builds back over the western
US Sunday and slides eastward into the central rockies/plains
through the first half of next week. There may be a few quick moving
shortwaves initially as the plains remain under northwest flow...however
with substantial/deep dry air mass in place measurable precipitation
appears unlikely with these features. As the ridge slides east
warm/dry conditions should dominate with above normal temperatures
at least through next Tuesday with highs in the 60s returning
early next week. European model (ecmwf)/GFS/gefs show increasing spread by
Wednesday as European model (ecmwf) shows a shortwave trough cutting through the
northern extent of the riding and pushing a cold front
south...which GFS keeps the ridging in place. For now I leaned
towards consensus/persistence (above normal/dry).
Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1028 am MST Wednesday Feb 10 2016
At this time VFR conditions are expected through the period. From
now until near 00z...west to northwest winds of near 15 knots with
gusts into the 19 to 23 knot range are expected at both sites.
Later tonight a front will move in from the east and get close to
kmck. It is possible that some stratus may affect the site. At
this time chose to only have a scattered deck in for kmck. This
will have to be watched closely.