Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 152002

Area Forecast Discussion
National Weather Service Goodland KS
102 PM MST Thu Feb 15 2018

.SHORT TERM...(Today through Saturday night)
Issued at 345 AM MST Thu Feb 15 2018

Synoptic Overview: A weak surface low over northern KS will
progress to the MS river valley today as a de- amplifying
shortwave lifts rapidly northeast from the Central Plains to the
Upper Great Lakes. Canadian high pressure will build quickly
southward through the Dakotas into the Central Plains this
afternoon and evening in assoc/w subsidence in the wake of
shortwave energy progressing east of the Rockies /ejecting across
the Northern Plains/. Meanwhile, additional shortwave energy (in
northern CA/NV this morning) will de-amplify as it progresses
across the central Rockies into the Central/Northern Plains this
afternoon and evening. A series of small amplitude waves will
traverse the region in NW flow aloft Fri-Sat, with flow aloft
backing to the west later this weekend as more substantial
shortwave energy moves ashore the PAC NW.

Today/Tonight: A cold front will surge southward through the Tri-
State region today as Canadian high pressure progresses from the
Dakotas to the Central Plains. Highs today will largely be a
function of 1) cold advection in the wake of the frontal passage
this afternoon (esp to the north) and 2) increasing mid/upper
level cloud cover from the W/WSW. At this time expect highs
ranging from the upper 40s (N) to upper 50s/lower 60s (S). Winds
will become NNW at 15 to 20 mph late this morning and early this
afternoon as a weak sfc low progresses east of the region. In the
wake of the cold frontal passage, winds will veer to the N/NNE
and increase to 20-30 mph sustained with gusts up to 40 mph for
several hours late this afternoon and evening (primarily between
00-06Z) when cold advection /pressure rises/ are progged to be
most pronounced. A short period of light precipitation (SN or RA=>SN)
will be possible in the same time-frame, however, due to the
brief/light nature of precipitation in addition to uncertainty
with regard to p-type at onset, little accumulation is
anticipated. At most, a half inch to an inch may be possible,
primarily in eastern Colorado. Temperatures tonight are expected
to fall into the teens, driven primarily by cold advection.

Fri/Fri night: Canadian high pressure will progress eastward from
the Central Plains to the MS river valley in this period as a lee
cyclone develops in advance of additional shortwave energy
progressing toward the region in NW flow aloft. Southerly return
flow will develop/strengthen from west-east Friday afternoon,
with highs ranging from the 30s to 40s, coldest in northeast
portions of the area. Southerly flow may reach 20-30 mph sustained
with gusts to 35-40 mph for a short period late Fri afternoon and
evening, particularly S/SW of I-70. Expect moderating temps with lows
in the 20s.

Sat/Sat Night: Winds will shift from S to NW on Saturday as the
aforementioned shortwave energy /attendant lee cyclone/ progress
east of the Central Plains. However, in the absence of a cold
upstream airmass, expect neutral thermal advection with highs Sat
in the 40s to perhaps lower 50s (S/SE). Winds will back to the
south and strengthen to 15 to 25 mph with gusts up to 35 mph
Saturday night as flow aloft backs to the west, a sfc trough
deepens in the lee of the Rockies, and the MSLP gradient tightens
over the High Plains.

.LONG TERM...(Friday night through Thursday)
Issued at 100 PM MST Thu Feb 15 2018

Friday night-Sunday: Shortwave ridging transitions over our CWA
Friday night, with west then southwest flow developing Saturday
through Sunday. Pattern will remain dry with a warming trend through
the weekend. A quasi-stationary front lingering through Saturday
morning eventually lifting north as a warm front as lee trough
deepens Saturday afternoon. Strongest WAA Sunday may be associated
with strong southwest flow ahead of an approaching arctic front.

Surface pattern and mixed layer winds are uncertain Sunday which
will determine potential for RFW conditions to be met. Due to the
mild temperatures and dry air mass in place RH will likely reach 15
percent at least for a period in the afternoon Sunday.

Sunday night-Thursday: Longwave trough develops across the western US,
with an arctic front moving over our CWA Sunday night and Monday.
Several shortwave troughs break off the main upper low and
transition across the Rockies and Plains, and could result in
increasing snow chances (deepening on evolution/track). Models are
coming into better agreement for snowfall Monday night through
Tuesday morning, however still vary on amounts. ECMWF shows a
stronger lobe of vorticity and more of a closed H7 center which
would represent better potential for stronger forcing in our NW CWA.
GFS is weaker and shows less amounts accordingly. For now consensus
is for sub advisory amounts (generally around 1"), but this could
change if we see good banding and a slower transition eastward.
Shortwave ridging is currently shown to move over our CWA by
Thursday and help bring dry conditions and a slow moderation in
temps (particularly Thu ahead of next trough).


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1029 AM MST Thu Feb 15 2018

For KGLD...VFR conditions thru 00z Friday w/ increasing low/mid
ceilings. 00z-09z...MVFR with 5sm in light snow and ceilings BKN-
OVC020-030. From 09z onward...VFR conditions.

Winds...NW 10-20kts thru 19z then N 20-30kts. By 09z Friday...N
around 10kts shifting to the SW by 14z.

For KMCK...Mainly VFR conditions thru the forecast period...w/
MVFR conditions from 00z-08z with ceilings OVC030 and flurries.

Winds...N around 10kts thru 20z then N 20-30kts. By 08z
Friday...NW around 10kts becoming SW around 10kts by 14z.




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