Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 201927
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
127 PM MDT WED JUL 20 2016

.SHORT TERM...(This afternoon through Thursday)
Issued at 127 PM MDT Wed Jul 20 2016

Large scale mid-upper level ridging continues to dominated the
pattern across the US, with monsoonal flow (apparent on WV imagery)
rotating around the western edge of the ridge.

Regarding heat advisory: Temperatures are still in the process of
increasing early this afternoon and already in the mid to upper 90s
for most locations. Tds have mixed lower in the west (as expected),
however they have held up in our east and heat index values should
approach advisory criteria before temperatures begin decreasing.
There is a little less certainty on highs Thursday due to the
possibility of better thunderstorm coverage (discussed below),
however consensus continues to favor at least similar highs as today
and possibly higher Tds raising the possibility some eastern
locations could see heat indices approach 110. Friday highs are
discussed in the long term section. Confidence continues to remain
high enough to maintain current advisory through Friday, though
there could be a larger spread in heat index values in advised area
than currently indicated.

This afternoon-Tonight: Shower/thunderstorm activity has already
developed over higher terrain in colorado and mean flow sill tend
to bring this towards the northwest part of our CWA. Local CAPE
values are relatively weak (500 J/KG MU CAPE), CIN is very strong,
and with main region of forcing well to the west I am not confident
we would see see local initiation this afternoon in all but our far
west near surface trough axis. Better chances would be associated
with activity spreading eastward or outflow weakening the CIN
locally. Strongest signal from high resolution guidance is in our
far western CWA, and this is where I kept chance PoPs.

Thursday: There is a shift in the ridge to the east allowing for
southwest flow to develop over our cwa. This shifts the monsoonal
axis towards northwest Kansas and results in increasing in moisture
profiles and forcing above 700mb. Higher resolution guidance still
favors isolated to widely scattered activity, however considering
the shift in pattern I could see coverage being better than
consensus indicates. CAPE values increase to the 1500-2000 J/KG
range, however effective bulk shear will roughly be in the 15 kt to
25 kt range, so an organized severe threat is unlikely. PWAT values
will increase to be almost 1.5" and considering warm air mass and
skinny CAPE profiles we could see localized heavy rainfall with any
thunderstorm activity.

.LONG TERM...(Saturday through Tuesday)
Issued at 233 AM MDT Wed Jul 20 2016

Ridge breaks down and slides westward as we head into Saturday and
Sunday. A nearly stationary theta-e boundary associated with a
cold front will be in place from southwest to northeast across
the CWA on Saturday and will strengthen as we head into Sunday,
allowing for slgt chc to chc PoPs across the area mainly during
the mid afternoon through late evening. Surface low pressure will
remain in place in the vicinity of this boundary due to lee side
upper level divergent flow. CAPE values are expected to be up to
1600 J/Kg and shear will be very low thus severe potential will be
limited to gusty winds and perhaps large hail in the presence of
DCAPE values around 700 to 1200 J/Kg. Much cooler temperatures
much closer to seasonal averages will prevail in the wake of this
cold front.

Troughing will take shape over the eastern US as we head into
Monday. A cold front will push southward at this time and back into
the CWA on Monday afternoon, giving us another chance of
thunderstorms through the day and into the evening. There is some
disagreement with the placement of the front however; both global
models indicate the same general timing of the feature. The front
will wash out as we head into Tuesday and a ridge will begin to
build over the western states.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1119 AM MDT Wed Jul 20 2016

VFR conditions will continue through the TAF period at both KGLD
and KMCK terminals. Thunderstorm activity may develop along a
surface trough in eastern colorado and move into northwest Kansas
and southwest Nebraska. Confidence was too low to include mention
in either KGLD or KMCK TAF as coverage may remain very isolated.
Winds should remain less than 12kt through the TAF period, though
a LLJ developing tonight may lead to low level wind shear
developing at both terminals. Confidence was higher in wind shear
at KMCK, so I left mention out of KGLD for now.


&&

.GLD Watches/Warnings/Advisories...
KS...Heat Advisory until 7 PM CDT Friday for KSZ002>004-014>016-028-
     029.

CO...NONE.
NE...Heat Advisory until 6 PM MDT /7 PM CDT/ Friday for NEZ079>081.

&&

$$

SHORT TERM...DR
LONG TERM...TL
AVIATION...DR


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