671 
FXUS63 KGLD 212350
AFDGLD

Area Forecast Discussion
National Weather Service Goodland KS
550 PM MDT Wed Jun 21 2023

.MESOSCALE DISCUSSION...
Issued at 526 PM MDT Wed Jun 21 2023

Key Message: Strong to severe thunderstorms continue over parts of
Eastern CO. The activity will eventually shift southeast out of 
CO this evening. Low end severe weather may occur this evening 
after storms merge together.


Unseasonably high CAPE values are in place over Eastern CO into
Western KS. At the surface there is a weak warm front over
Southeast CO. A weak boundary extends northward to Akron that
isolated storms are building on. In the Akron, CO area an upper
level short wave trough and surface low have produced a favorable
environment for supercells to form that have produced a number of
tornadoes this afternoon.  

Am thinking this activity will congeal into one main mass and then
move southeast. This is what should bring storm activity to a
large part of the forecast area tonight. Confidence for severe
weather is moderate. The effective shear declines ahead of the
anticipated MCS, down to 20 kts or so. In addition the CAPE
remains high enough for severe weather, however the CINH
increases ahead of the storm activity. However, looking soundings,
there is a good deal of elevated CAPE to work with above the
inversion. Therefore, low end severe weather is not out of the 
question. Am thinking the main threat will be flooding from the 
prolonged rainfall. Storms shouldn't be producing large hail due 
to the many updrafts in close proximity, and the wind threat 
shouldn't be too great due to the inversion being present, 
although a few random gusts around 60 MPH couldn't be ruled out 
due to the moisture advection potentially eroding the inversion.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 1240 PM MDT Wed Jun 21 2023

As of 1 pm CDT, 12 pm MDT, skies across the Tri-State Region were 
partly to mostly cloudy as a result of morning stratus/cumulus as well 
as convective blow off from the overnight elevated storms across 
north central Kansas. Clouds have held temperatures in the 70s so 
far today although a few 80s are starting to show up where more 
sunlight has been received. Low level moisture is quite impressive
with dewpoints in mid 60s with a few readings to around 70, well 
above normal for this time of year. Winds were generally from the 
east at 10-15 mph. At the surface, a clear outflow boundary was 
visible extending from northern Yuma County to around Goodland, 
Kansas and finally to near Russell Springs, Kansas. It's moving to
the west, and should continue to do so over the next few hours. 
Aloft, a shortwave trough is moving northeast, towards the Plains,
across northern New Mexico. Recent KGLD WSR-88D radar imagery and
GOES satellite imagery indicate recent convective initiation 
along the boundary in Yuma County Colorado.

For the rest of the afternoon and into the evening hours, the main 
focus will be this convective outflow and storms firing on that outflow 
across eastern Colorado. Latest mesoanalysis indicates quite an 
unstable environment has developed with SBCape of 2000-5000 j/kg, low 
level lapse rates of 7+ C/km, and DCape of 1000+ j/kg available for 
storm development. Wind shear is presently a limiting factor with 0-6 
km bulk shear of less than 25 kts and 0-3 km SRH nearly non-existent at 
this moment in time. CIN is near zero which is why we're seeing storms 
develop along this outflow boundary. Overall, expect storms to continue 
attempting to fire on the outflow, and eventually some of them will be 
able to sustain themselves. Low level shear should increase later, 
closer towards 6 pm, and with LCLs quite low today, wouldn't surprise 
me if these initial storms were able to produce a tornado or two. Heavy 
rainfall may also be a problem with slower storm movements.

For later tonight, expecting a larger complex to form out of the 
evening convection forecast to fire along and just east of the Front 
Range, east of Cheyenne, WY and Denver, CO. Overall, this looks like a 
fairly confident forecast with the storms moving over as there will be 
plenty of instability to work with, and higher DCape values should 
promote a cold pools/outflow which will help organize the thunderstorm 
complex. The main threats with this complex will be damaging winds and 
also torrential rainfall, especially if there's backbuilding on the 
southwest side of the system as some models indicate. As a result of 
all of this, the flood watch looks good to go and we should see some 
widespread heavy rain. Latest guidance did back off some on how far 
east the complex will make it, so that's something to be mindful of.

For tomorrow, the overnight complex should have an impact on the 
environment, though currently not sure how much of an impact. There 
should be remaining cloud cover, and perhaps some ongoing shower and 
thunderstorm activity during the morning. During the afternoon, 
instability will once again build and we should see initiation along 
any remnant outflow boundaries. As a result of the previous night's 
convection, the instability isn't nearly as high as what we're 
currently observing. Wind shear does improve tomorrow though, with 0-6 
km bulk shear of around 30-35 knots anticipated, so that may be a 
compensating factor. The biggest question will be the CIN as a result 
of the anticipated MCS and resulting daytime cloud cover. Overall, do 
expect thunderstorm development during the afternoon, and some of these 
could be strong to severe. However, did go ahead and lower pops as it 
seems convection will be more isolated to scattered, not widespread as 
previously anticipated. During the evening and overnight hours, it does 
look like another complex of storms moves through the area from 
northwest to southeast. There may be some potential for damaging winds 
again, though the primary threat seems more likely to be heavy
rainfall.

.LONG TERM...(Friday through Wednesday) 
Issued at 155 PM MDT Wed Jun 21 2023

Another round of severe weather is expected to start off the 
extended period on Friday. The latest guidance is showing a 
low/trough along the Front Range begin to slowly shift eastward late 
in the day towards the KS/NE border. There is a weak 500/700mb 
shortwave that works northeast along the periphery of the upper 
ridge in the Plains. This will interact with the surface feature by 
late afternoon into the evening hours to trigger some convection. 
With a moist airmass in place with dewpoints in the 60s, PW values 
are ranging from 0.90" west to the 1.50" mark east where the best 
low level moisture resides. There will be a strong S/SE surface 
gradient with gusts to 30 mph. Aloft, SW flow 20-30kts will provide 
some decent shear with storms. Sfc/MUCape values around the 2000-
2500j/kg level with provide fuel to trigger strong to severe storms. 
SPC continues to have Slight/Marginal risk areas for the 
afternoon/evening hours. Best chances for severe potential look to 
occur along/north of the Interstate, which tracks areas closer to 
the surface low/trough that moves off the Front Range. WPC does have 
a Marginal risk for excessive rainfall for mainly east of the 
Colorado border. Torrential rainfall is probable with yet another 
flood watch likely, but areas will be determined on what counties 
get affected wed/thu.

This system clears the area by the upcoming weekend allowing for a 
warm and dry period. Meandering upper ridge will provide a W/SW flow 
aloft during this time. The ridge does sink a bit going into the 
first half of next week as a couple shortwaves will move across the 
northern periphery of the system. Passage will occur for the evening 
and overnight hours, allowing for a dry yet humid daytime period(s) 
each day through Wednesday. Best chances for storms will occur north 
of the Interstate. While strong to severe storms could occur, with 
high PW values/dewpts, heavy rainfall will probably occur in spots 
and need to be monitored as the week progresses.

For temps, daytime highs for Friday into the first half of the 
upcoming weekend will have low to mid 80s give way to mainly upper 
80s to the lower 90s on Saturday, with warmest areas east. Going 
into sunday, northerly flow will bring a cooler wider range with 
upper 70s west into the upper 80s east. For the first half of next 
week and that models carry most of the precip at night, mainly 80s 
expected with some locales east around 90s, especially Wednesday. 
Overnight lows will have mainly 50s with some 60s east for Friday 
night into this weekend. For Monday night onward, 60s will begin to 
build in from the east.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 526 PM MDT Wed Jun 21 2023

VFR to MVFR conditions forecast for the TAFs. Main impact will be
the storm activity impacting both TAF sites. The storm activity in
CO will move east out of CO during the evening. The activity may
reach KGLD as soon as 6z and KMCK as early as 9z. KMCK should be
north of the majority of the storm activity. Difficult to
determine how long the storm activity will last for KMCK.

Another round of storm activity may move through the TAF sites
during the latter half of the morning.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Flood Watch through Thursday morning for KSZ013-014-027-028-041-
     042.

CO...Flood Watch through Thursday morning for COZ090>092.

NE...NONE.
&&

$$

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