Issue Date: Thursday, August 23rd, 2018
Issue Time: 09:40AM MDT
— NO flood threat today.
After sponsoring a round of showers and thunderstorms across the northwestern portion of the state last night, an upper-level trough over Wyoming is now quickly moving off to the east. Moisture is starting off high ahead of this feature in many areas today (approaching the 90th percentile values for August 23rd at both Grand Junction and Denver), but the back (west) side of the trough will usher in predominantly subsident air. Subsidence produces warming and drying and will also help suppress any convection that attempts to develop this afternoon; this is evident in this morning’s lower-level water vapor imagery, which shows that the trough axis divides a starkly drier airmass to the northwest from the moist monsoon flow to the south.
While the trough is progressing to the east fairly rapidly, it may take much of the day for dry air to take hold across the southern 1/3 or so of the state. Where above-average moisture lingers, a few storms are possible, particularly across the high terrain. With a predominantly subsident airmass and storm motions of 20-30 mph, storm coverage is expected to be limited and they should move to the east or east-southeast at a sufficient rate to avoid flood concerns. Any storms that do develop may be capable of producing brief gusty winds, but a substantial severe weather threat is not expected today.
Today’s Flood Threat Map
For more information on today’s flood threat, see the map below. For Zone-Specific forecasts, scroll below the map.
Zone-Specific Forecasts:
Northwest Slope, Northern Mountains, Grand Valley:
Showers that lingered from last night’s area of rain have faded out as of the forecast issuance time. Sunny but smoky skies are expected for the rest of the day, with some fair-weather cumulus possible over the mountains later in the afternoon. No additional notable rainfall is expected.
Southwest Slope, San Juan Mountains, Central Mountains, San Luis Valley, Southeast Mountains, Raton Ridge, Southeast Plains:
Some cloud cover is present across mountainous areas this morning, but skies may be expected to generally clear. Isolated storms may develop this afternoon, primarily in the higher terrain, moving east-southeastward at 20-30 mph. Rainfall rates should primarily be just 0.10-0.20 inches per hour or less. An isolated late-evening storm is also possible on the eastern plains. Smoke blowing in from the west-northwest is also expected to increase this afternoon and evening.
Primetime: 12PM to 10PM
Front Range, Urban Corridor, Palmer Ridge, Northeast Plains:
Areas of clouds this morning are expected to decrease throughout the day as drier air aloft moves in. Smoke will also become more prominent, however, so hazy skies and deteriorating air quality should be expected as well. Temperatures should be right around seasonal averages, with highs in the mid-80s °F on the plains.
