235 
FXUS65 KBOU 281606
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1006 AM MDT Sat Apr 28 2018

.UPDATE...
Issued at 1006 AM MDT Sat Apr 28 2018

Forecast is on track with warmer weather today and a few
showers/storms mainly over the mountains this afternoon and
evening. A few of these could still drift off the Front Range and
into the I-25 Corridor late in the day, producing gusty winds up
to 45 mph and just a brief sprinkle/light shower. We have nudged
up high temps a couple degrees based on the latest 12Z raobs and
lack of significant mid level moisture. However, composite Layered
Precipitable Water products show this mid level moisture slowly
arriving from the southwest this afternoon to help the isolated to
scattered convection. 

&&

.SHORT TERM...(Today and tonight)
Issued at 400 AM MDT Sat Apr 28 2018

A plume of mid-level moisture ahead of weak shortwave trough 
riding up the west side of a mid-level shortwave ridge presently 
over western Colorado will continue its slow eastward progression 
across Colorado today. The shortwave itself was still back over 
wrn Utah/n-central Arizona. GOES-16 IR and H20 Vapor imagery 
indicate the core of this moisture is just about to reach wrn 
Colorado. Model soundings indicate the bulk of this moisture is 
concentrated within the 500-400mb layer. Should see the leading 
edge of this moisture reaching the CWA's high country by late 
morning, and therefore a fairly quick increase in convective cloud
formation with strong solar heating, and not long after that 
shower development mainly over the higher terrain. By mid to late 
afternoon further increase in moisture and instability should 
lead to scattered showers and isolated t-storms across the high 
country, with southwesterly flow concentrating the greater precip 
producing showers over the high terrain generally south of I-70. 

Meanwhile east of the mtns...the passing upper ridge this morning
and dry west-northwest flow aloft will allow for strong solar 
heating to quickly drive temperatures up into the upper 60s/70s by
midday, ending up with low-mid 70s for highs on the plains, and
balmy 50s and 60s in the high country. The strong heating will 
further strengthen the sfc trough up along the Front Range, which
will steepen the pressure gradient between this trough and the 
strong sfc high crossing cntrl Nebraska. The result will be gusty  
winds on the plains later today, esply east of a Ft Morgan-to- 
Elbert line where sely winds of 25-30kts could linger until early 
this evening. West of there, winds are not expected to be as 
strong but still in the 15-25kt range after 18z. With the ridge 
migrating east of the area this afternoon, should see a steady 
increase in mid and high clouds and later a stray showers and/or 
t-storms moving off the foothills. Would not expect to any shower
activity east of the I-25 corridor where the boundary layer 
should remain capped due a weak intrusion of slightly cooler and 
more humid air in the past couple of hours. 

Tonight, should see an end to most the shower activity before 
midnight and gradual clearing from west to east with the influx of
drier warm air from the Desert Southwest. As a result, overnight 
lows should be a few degrees warmer, esply in downslope areas 
along the foothills.

.LONG TERM...(Sunday through Friday)
Issued at 400 AM MDT Sat Apr 28 2018

Much of the upcoming week will be characterized with a moderate
southwest flow regime with the mean trof position over the Great
Basin. Several disturbances will move across Colorado resulting 
in a more active upcoming weather week with an increase chance of
thunderstorms and elevated fire weather concerns over portions of
the plains.

For Sunday, Colorado will be under an increasing southwest flow 
as a ripple in the flow rapidly moves through Colorado during the 
day. The airmass really dries out behind it with the possible 
exception of the far eastern plains of Colorado where dry line set
up may still be over the far northeast plains with potential CAPE
values of 800-1300j/kg. Models have the drier air almost to the 
Kansas border before 00z with the potential for thunderstorms 
pushing east of Colorado by evening. Temperatures will be very 
warm on Sunday afternoon with readings closing in on 80 degrees on
the plains as 700mb temperatures will be +10c and should have a 
well mixed airmass up to 500mb. With the well mixed airmass, 
expect gusty southwest winds as well over portions of the plains, 
especially Palmer Divide and further east. 

Deepening low pressure over the Great Basin on Monday will result
in stronger southwest winds on Monday while a cold front expected
over northeast Colorado Monday afternoon/evening. This could
result in a few showers/thunderstorms with the frontal boundary
interaction with potential CAPES up to 1500j/kg. Airmass is still
somewhat dry so overall pops will be on the low side. Cooler and 
more moisture on Tuesday would result in higher chances of showers
and thunderstorms. The upper low over the Great Basin begins to 
eject and weak and becomes more disorganized as it moves over 
Colorado in the Wednesday/Thursday time frame. Certainly this time
frame will have the best chances for showers/storms and cooler 
temperatures over the mountains and plains. 

Friday and Saturday look to be drier and warmer as high pressure
builds over the region under a northwest flow regime. 

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1006 AM MDT Sat Apr 28 2018

VFR conditions today and tonight at Denver area terminals. High
based convection late this afternoon may produce a period of gusty
southwest winds with 35 knot gusts possible, but the chance of
seeing thunder at any of the TAF sites is only around 10-15%. Main
threat of the gusty winds/high based showers is 23Z-04Z. 

Variable winds this morning will turn more east/southeast this
afternoon and gradually increase. Look for a later arrival of
gusty winds than earlier forecast, with gusts reaching 20-25 knots
at KDEN and KAPA after 22Z, and then weaken again to around 10
knots after any potential gusty shower outflows. 

&&

.FIRE WEATHER...
Issued at 400 AM MDT Sat Apr 28 2018

Will be begin to see an increasing threat of critical fire weather
conditions by later this weekend and especially Monday afternoon.
The plains will be under an increasing southwest flow aloft and
dry conditions. The driest and windiest day looks to be on Monday
afternoon with low humidities and gusty southwest winds. Main
impact areas would be over eastern Elbert, Lincoln and portions of
Washington counties. No watches will be posted as of yet. 

&&

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

$$

UPDATE...Barjenbruch
SHORT TERM...Baker
LONG TERM...Entrekin
AVIATION...Barjenbruch
FIRE WEATHER...Entrekin