Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 282052
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
252 PM MDT Fri Apr 28 2017

.SHORT TERM...(This evening through Saturday)
Issued at 216 PM MDT Fri Apr 28 2017

Latest upper level analysis shows a closed low over the central
Rockies. Ahead of the closed low southwest flow was pulling higher
moisture onto the High Plains. At the surface a cold front was
near the I-70 corridor. Behind the front northeast winds were
gusting up to 30 MPH.

Tonight the cold front will slide south through the rest of the
forecast area in the evening. Any lingering thunderstorms will be
pushed south with the front. Meanwhile frontogenesis and
isentropic lift will develop over the forecast area, with the
lift/frontogenesis strongest over the southeast portion of the
forecast area. At the surface rain will change to snow from west
to east as temperatures cool. The higher snowfall amounts for the
night will occur after midnight when the lift/frontogenesis will
be strongest.

Saturday morning there will be a lull in the precipitation
intensity. Light precipitation will continue as weak frontogenesis
and isentropic lift continue. In the afternoon a stronger band of
frontogenesis and isentropic lift will develop over the southeast
half of the forecast area, causing precipitation intensity to
increase.

Snow will change back to rain generally north of I-70 and east of
Highway 83, but how quickly this change-over occurs is highly
dependent on temperature. If temperatures are a couple degrees
cooler than forecast, snow will persist longer through the day
before changing to rain, if it changes over.

Saturday night through Sunday the main snowfall event will occur
as strong, deep isentropic lift and repeated rounds of
frontogenesis move over the southeast half of the forecast area.
Snowfall amounts are actually lower Saturday night than what they
should be based on the lift due to a dry pocket of air moving
north over the area. As precipitation ends from west to east
Sunday afternoon, the snow may change to rain as warmer
temperatures move in behind the storm system.

Sunday morning into early afternoon strong to possibly high winds
will occur mainly east of the Colorado border and west of Highway
83 on the back of the storm system. Considered issuing a high wind
watch, but confidence was too low at this time to warrant a
watch. Am expecting gusts of 55 MPH in this part of the forecast
area, but a few gusts near 60 MPH can`t be ruled out.

Snowfall for this storm system will come in two different rounds.
The first round will begin tonight and last through Sunday evening
for counties in the winter storm warning, with next round starting
Saturday night in watch area and lasting through Sunday evening.
Due to the change- over of rain to snow being dependent on
temperatures there will be a sharp cut- off between the higher
snowfall amounts and the lower snowfall amounts along the Highway
36 corridor up to McCook. Could have gone either way including
Cheyenne County KS in the warning, but decided to play it safe and
include them since current forecast has 7 inches in the far
southern part of the county. If temperatures are a couple degrees
cooler for the forecast area, snowfall amounts will be higher.
Already cooled temperatures a couple degrees below most models,
but that may have not been enough.

Looking at CIPS Analog analysis, this event is similar to the
April 2, 1988 and the April 12, 1994 events which both had close
to a foot of snowfall with them. Current forecast has close to a
foot of snow south of I-70.

Impacts with this storm system will be tree limbs breaking and
possibly power lines being blown down from the weight of the
heavy wet snow combined with the strong winds. As such people
should make preparations for no power during the storm. The cold,
wet conditions, with wind chills in the teens and 20s, will be
very hard on newborn livestock.


.LONG TERM...(Monday through Friday)
Issued at 114 PM MDT Fri Apr 28 2017

For the extended period...the passage of the weekend storm off to
our east will allow the Tri State region to have a dry day ahead of
next system...set to affect the region by midweek. The passage of
the expected shortwave will bring a round of shower activity to the
region. By Wednesday night on into Friday...broad H5/H7 ridging
builds over the western half of the country setting the area up for
a warming trend by the end of next week.

On Monday...short-lived ridging over the area thru the day before
the arrival of the next system looks to afford the area msunny
conditions at best...and with WNW surface flow over the area...not
big rebound in area highs temps...with mid and upper 50s at best.

For Monday night on thru the day Wednesday...H5/H7 shortwave will
approach the region from the NW...swinging thru the area before
exiting east on Wednesday. Inverted surface trough does work out
ahead of the shortwave late Tuesday into Wednesday. Deeper
moisture/QPF does look to be focused more along the surface trough
and will limit overall QPF totals for the area as this system exits
east before bulk of mid level shortwave arrives into the CWA.
Overall QPF for this system will bring rainfall totals near 0.10-
0.30" and with lack of instability there is no mention of thunder in
to enhance any local totals. Temps during this period fairly steady
due to expected cloud cover. Looking for highs on Tuesday/Wednesday
from the upper 50s to lower 60s at best...off of overnight lows
mainly in the mid to upper 30s. Main p-type will be showers...w/
some spotty -sw in our far western zones in Kit Carson county w/ no
accum expected.

Going into Thursday and Friday...models showing warming trend is on
tap...as strong mid level ridging pushes eastward from the west
coast...nosing into the Plains region by Friday. Strong subsidence
associated with this ridge and surface ridging will give daytime
highs Thursday well into the upper 60s...and by next Friday 75-80F
is possible. Overnight lows will be in the low 40s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1146 AM MDT Fri Apr 28 2017

COMPLICATED FORECAST OVER NEXT 24 HOURS. AN AREA OF STRATUS
REMAINS ALONG AND NORTH OF I-70, IMPACTING BOTH THE KMCK AND KGLD
SITES. STRATUS EVENTUALLY SPREADS SOUTHWEST THIS AFTERNOON WITH
CEILINGS LOWERING AS WE APPROACH THIS EVENING. HOWEVER, TIMING
REMAINS A LITTLE UNCERTAIN REGARDING THE TIMING. ONCE STRATUS
SPREADS SOUTHWEST, ANTICIPATE IFR CEILINGS FOR MOST OF REMAINING
TAF PERIOD. SHOWERS/ISOLATED STORMS SHOULD DEVELOP THIS AFTERNOON
AHEAD OF AN APPROACHING COLD FRONT. AS OF NOW, STORMS SHOULD
REMAIN SOUTHWEST OF KGLD WITH NO THREAT FOR KMCK. LATER THIS
EVENING, WIDESPREAD PRECIPITATION DEVELOPS. PRECIP TYPE WILL
INITIALLY BE RAIN BUT A CHANGE TO SNOW IS FORECAST. REDUCED
VISIBILITIES FROM FOG, DRIZZLE, AND SNOW SHOULD BE EXPECTED.
NORTHEAST WINDS WILL INCREASE IN SPEED, PARTICULARLY AFTER
MIDNIGHT WHEN A SURFACE LOW INTENSIFIES TO THE SOUTH.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Winter Storm Watch from Saturday evening through Sunday evening
     for KSZ002>004-014>016-028-029.

     Winter Storm Warning from midnight MDT /1 AM CDT/ tonight to 6
     PM MDT /7 PM CDT/ Sunday for KSZ001-013-027-041-042.

CO...Winter Storm Warning from midnight tonight to 6 PM MDT Sunday
     for COZ091-092.

NE...Winter Storm Watch from Saturday evening through Sunday evening
     for NEZ081.

&&

$$

SHORT TERM...JTL
LONG TERM...JN
AVIATION...RRH



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