Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/20/20

Area Forecast Discussion

National Weather Service Denver/Boulder CO

 814 PM MDT Sun Apr 19 2020

.UPDATE...
Issued at 813 PM MDT Sun Apr 19 2020

Satellite and radar pictures are still showing some weak
convective clouds and a few showers over the CWA right now. There
is still quite a bit upstream as well, so some should continuing
moving over the CWA well after sunset. Skies should stay at least
"party cloudy" much of tonight. Will make some slight GFE grid
adjustments to pops in the mountains, sky cover and winds.

&&

.SHORT TERM...(This evening through Monday)
Issued at 240 PM MDT Sun Apr 19 2020

Convection in the northwest flow aloft is spreading across the
higher terrain and over the Palmer Divide. Looking at recent ACARS
soundings from aircraft shows an inversion around 800 mb keeping
most activity off the plains. However, as the shortwave and
accompanying cold front sliding down over Wyoming and into western
Nebraska nears, will see more activity along the northern plains
later this afternoon into the early evening. Activity will likely
increase over the northern mountains as well, as the activity to
the south decreases with the loss of sun`s heat. Threats from the
weak thunderstorms will be lightning, gusty outflow winds and
possible pea-sized hail over the far northeastern corner. A chance
for snow showers over the high terrain will remain most of the
night as the upper shortwave slows down to remain over northern
Colorado.

Expect warmer temperatures Monday as 500mb height slowly rise,
however another shortwave moving into western Colorado will bring
showers and possible thunderstorms mainly over the higher terrain along
and south of I-70. A more stable airmass will be found over the
plains that should inhibit convection.

.LONG TERM...(Monday night through Sunday)
Issued at 240 PM MDT Sun Apr 19 2020

Model consistency has improved with regards to a trough that is
projected to pass south of the region on Tuesday. Some enhanced lift
will be present with increasing ascent mainly south of I-70 that
will bring some scattered showers and a few storms by the afternoon
hours. Current 700 mb temperatures and wet bulb values project snow
will be possible around and above 10,000 ft with accumulations
ranging from just a trace over the northern mountains up to 6 for
the higher elevations south of Berthoud Pass by Tuesday evening.
Temperatures will be in the mid- to upper- 60s across the plains
with near 70 for the far northeastern plains counties.

As the trough continues transitioning across the desert southwest
and into the southern great plains on Wednesday, subsident flow will
increase drying out conditions across the CWA. Will maintain a
slight chance over the western facing slopes across the northern
mountains to account for some weak moisture in the north to
northwesterly flow that could bring just enough instability for
isolated showers during the afternoon. Wednesday could see the
warmest temperatures of the week with most areas across the plains
seeing near or above 70 degrees with the mountains getting into the
40s and 50s.

As the trough kicks out over the lower Mississippi rive valley the
region will be under moderate northwest flow aloft. Global models
diverge slightly on the strength and timing of these disturbances.
For instance, the GFS is being more aggressive with a digging trough
into the state late Thursday into Friday that could bring increased
showers and storms with the possibility of accumulating snow for
west facing slopes. Will maintain a slight chance with the EC
showing some returns as well, albeit slightly less pronounced.
Surface fields are also indicating the onset of a cold frontal
boundary late Thursday that will help to bring a slight chance of
precipitation to the plains into Friday with temperatures dropping
back into the 50s for the lower elevations.

Confidence breaks down entering into the weekend with models showing
differences in the timing and placement of the exiting trough. Will
lean towards a drying pattern with temperatures rebounding into
Sunday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 813 PM MDT Sun Apr 19 2020

Will continue to leave the showers out of the DIA TAF even though
there is weak convection around. None of the showers should hit
the ground. Most of the models show weak winds by 06Z tonight so
drainage wind directions look to be a good bet at DIA after
06-07Z.  There shouldn`t be any ceiling issues.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE.......RJK
SHORT TERM...Kriederman
LONG TERM....Bowen
AVIATION.....RJK