Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Goodland Kansas
727 PM MDT Tuesday may 5 2015
issued at 724 PM MDT Tuesday may 5 2015
Updated forecast to reflect the latest trends in radar data.
General trend from previous forecast was kept as far as rainfall
chances. Best chance for rainfall will be during the evening.
Overnight isentropic lift and drier air move into the area. There
is some lingering lift over the area so low rainfall chances seem
Short term...(this evening through wednesday)
issued at 1250 PM MDT Tuesday may 5 2015
Upper low currently over The Four Corners area early this afternoon
is forecast to lift northeast toward the Colorado/Wyoming border by 12z
Wednesday then into South Dakota by 00z Thursday.
First batch of moisture/rainfall spreading north across the area
early this afternoon and by the end of the day we may see a tapering
off of areal coverage across the south where some drier air starts
to move in. This trend continues overnight and especially after
midnight. For Wednesday some wraparound moisture and precipitation moves in
from the west.
Low temperatures tonight in the middle 40s to around 50 in far
eastern Colorado with low to upper 50s east of the state line.
Highs tomorrow in the upper 60s to low 70s in far eastern Colorado
with low to middle 70s east of the border.
Long term...(wednesday night through tuesday)
issued at 131 PM MDT Tuesday may 5 2015
Precipitation chances continue into Wednesday night as wraparound
moisture moves out of Colorado. Model quantitative precipitation forecast is generally less than a
quarter of an inch and with northwesterly surface winds developing
behind the surface front/loss of upslope component/not expecting
any Hydro issues. The front will stall out near the Kansas and
Oklahoma border Thursday afternoon...leaving the local area in the
cooler airmass resulting in only limited instability. Moisture
will however remain plentiful and with an upslope low level
component redeveloping there will be another chance of
precipitation mainly Thursday night with a shortwave trough moving
up from the southwest. Chances for light rain will continue
through Friday with moist easterly flow in the low levels and
another in the series of weak shortwaves aloft.
Saturday will be a bit different. The main cut off low will eject
northeast out of Colorado with a negative tilt. 500mb jet maximum
rounding the base of the system will result in deep layer shear
near 50kts. Instability will be the biggest question mark...but
GFS showing up to 1500 j/kg by the afternoon south of Interstate
70...which given the synoptic set up would be enough for a few
severe storms. The other concern will be quantitative precipitation forecast. Both the GFS and
European model (ecmwf) show 1 to 2 inches of rain possible in the 24 hour period
ending 12z Sunday. Given antecedent rainfall over the past week
and moist soil conditions ffg values may be lower and will have
to monitor for the potential of flash flooding.
Latest run of the GFS has thrown some doubt on the Sunday and
Monday period. It keeps the cut off low lingering over the area
for several days while the European model (ecmwf) lifts it out into Canada. Cut off
lows can be slow to move out so not going to dismiss the GFS
solution and keep some slight chances for precipitation through
Monday. Both models show shortwave ridging on Tuesday so will keep
that day dry.
Temperatures will generally be near to slightly below normal
through the long term period.
Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 559 PM MDT Tuesday may 5 2015
VFR to IFR conditions forecast for the 0z tafs. Low clouds/vis.
And rainfall will continue through the evening then end from east
to west overnight...although cannot rule out some isolated to
scattered rainfall. Am thinking once ceilings/visible drop this
evening they should remain down through the night and not improve
until the morning. Tomorrow scattered rainfall does look very
favorable...with chances for rainfall increasing during the
afternoon. Would expect similar conditions that occurred for today
As a side note...there is some uncertainty regarding the onset of
MVFR and IFR conditions for kmck. Based timing off of when lower
ceilings moved through sites to the south.