Wednesday - Partly Cloudy, with a chance for showers in the evening. High: 87-91
Wednesday Night - Partly Cloudy. Low: 72-76
Thursday - Clouds building through the day. Storms in the afternoon/evening. High: 86-90
Friday- Clouds moving out. High: 82-86
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Tuesday afternoon again brings a chance of isolated showers to Columbia. Showers that do develop will disappear as the sun goes down. Temperatures tonight will remain still fairly high for September, being in the low 70s. Wednesday will see abnormally high temperatures once again, with humidity also remaining high. In the afternoon, the chance for a few isolated showers on Wednesday is still there, however these will also fade as the sun goes down. Wednesday night will be even warmer than Tuesday night, with temperatures in the mid 70s. Thursday will see our next big chance at rain, with a cold front expected to sweep across the area in the late afternoon/early evening, bringing storms with it. Friday will see our cloud cover start to leave, with temperatures that are lower, but still above average, being in the mid 80s. Humidity is expected to be much lower, however, so it will be more pleasant outside.
Issued: 4:00 p.m. ; September 10, 2019
Technical Discussion (The nerdy stuff we are discussing in class!)
WPC Diagnostics prefer the 12Z GFS, and thus will be the model of choice. The 18Z HRRR and 15Z SREF will be used to supplement the forecast. Tonight will see the return for the possibility for pulse storms, given our high temperatures and dew points. The dew point at Sanborn is currently 71F, leading to muggy conditions outside, which is expected to continue through Thursday night. We will remain in south to southwesterly flow up until Thursday night, with these winds advecting moisture into the area. This moisture is being advected by a surface low based in southern Wyoming. While this low is advecting moisture, there is very poor showing of any WAA. No solenoids are being rendered near Columbia, as 500-1000mb thickness lines are widely spread and parallel to lines of MSLP. Thus, a warming trend is not expected through the week. Wednesday will see relatively high temperatures once again, with humidity values remaining high. 12Z GFS Skew-Ts were indicating some sort of lower level cloud cover popping in and out, and thus partly cloudy skies are expected. 18Z HRRR indicates that Wednesday will once again see a chance for pulse storms in the afternoon. Any storms or showers will die out as sunlight fades. Winds will remain out of the south, as our low over Wyoming will begin to trek eastward during the day Wednesday. As this low comes off the mountains, it will begin to deepen rapidly. This low will start to set up its stationary front into proper warm and cold fronts during the day Wednesday, however we will not be impacted by the cold front until Thursday. Thursday will see clouds building in ahead of the approaching cold front. Temperatures will remain high along with dew points. Cold frontal passage is currently expected in the late afternoon on Thursday, bringing with it a linear system. This MCS has the possibility to be severe, however SPC Day 3 Outlook has us on the edge of the marginal risk. 12Z GFS sounding based in Columbia at 21Z on Thursday has ~4000 J/kg of CAPE with a weak cap of 7 J/kg of CIN. PWAT values will be approaching 2 inches. DCAPE is expected to be around 800, and thus the potential for severe winds will need to be monitored. If any bowing sections were to occur over Columbia, severe winds would be likely. The GFS has pushed this even forward a couple hours, from being late Thursday night to Thursday evening since yesterday, with location of the front moving slightly north. This situation will need to be monitored as newer runs come out. Friday will see temperatures still remain unseasonably warm, however they will be cooler than the previous part of the week. The cold front that passes through Thursday will greatly decrease humidity, and thus make it feel less sticky than the previous couple of days. Clouds will move out with the cold front, and leave us with fairly clear skies Friday afternoon.