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FXUS65 KBOU 281622

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1022 AM MDT Sun May 28 2017

Issued at 1022 AM MDT Sun May 28 2017

No changes to the forecast at this time. Skies across the state
began the day cloud-free. Now a few fair weather cumulus are
popping up over the mountains and foothills. Expect to see clouds
continue developing through the afternoon with isolated/scattered
showers over the mountains. The plains should stay mostly sunny
through the afternoon.  


.SHORT TERM...(Today and tonight)
Issued at 423 AM MDT Sun May 28 2017

Drier air over Colorado today with a little warming both at the
surface and aloft. A little more moisture by afternoon will lead
to some convective cloud development, but a warmer layer around
500 mb should limit the depth. Still a chance of some showers, but
threat of thunder is lower and I will limit it to this afternoon.
Most likely area is over the mountain ridges and east slopes, and
also perhaps in the northeast corner this evening as a weak ripple
in the flow moves by with slight cooling aloft and a little surge
of north winds. Moisture associated with this will keep some cloud
cover around overnight, though the threat of showers should
diminish. Forecast highs today look good, models are showing a bit
more cold advection tonight so I lowered tonight's lows a couple
of degrees.

.LONG TERM...(Monday through Saturday)
Issued at 423 AM MDT Sun May 28 2017

There is a substantial upper ridge initially over the Great Basin
northward well into western Canada on Monday. It's axis moves 
slowly eastward into Utah by Tuesday. At 12Z Wednesday morning it
gets into western Colorado. The flow aloft is weak and 
northwesterly for the CWA Monday through Tuesday afternoon, 
becoming due westerly Tuesday night. The QG-Omega fields show 
benign energy for the forecast area in the synoptic scale Monday 
through Tuesday night. There is a weak cold front with upslope 
flow behind it for Monday. From Monday night through Tuesday 
normal diurnal wind patterns dominate the CWA. The low level dew 
points are in the 40s to lower 50s F for the plains and foothills 
Monday through Tuesday night. Moisture is pretty decent through 
the period. The QPF fields have measurable precipitation for the 
western 2/3rds of the CWA both late day Monday and late day 
Tuesday. There is decent CAPE progged both days, with the highest 
values over the mountains and foothills east of the divide into 
the western Urban Corridor. Cross sections show pretty steep 
lapse rates late day Monday. There is a more substantial mid level 
stable layer over the plains late day Tuesday. The current going 
"chance"s for pops over the western 2/3rds of the CWA during the 
late day periods look good. Maybe not as far east on Tuesday. For
temperatures, Monday's highs are 1.5-3.0 C cooler than this 
afternoon's readings. Tuesday's highs are 1.5-4.0 C warmer than 
Monday's. For the later days, Wednesday through Saturday, the 
upper ridge is over Colorado through Thursday. There is some weak
troughiness on the ECMWF Thursday night, and on the GFS Friday. 
There is more ridging on Saturday from both. There will be enough
moisture around for some late day showers and thunderstorms, more
so in the high country. Temperatures will be near seasonal 
normals all four days. 


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1022 AM MDT Sun May 28 2017

VFR conditions through tonight. Just a slight chance of showers or
thundestorms moving off the mountains between 3 PM and 8 PM. KBJC
would have the best chance of seeing and showers. KDEN should see
no aviation impacts. 




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