4/18 – The Chief’s “Modifying Air Mass” Tuesday Morning Forecast
The upper troughs are located north of the Great Lakes and off the British Columbia coast this morning with high pressure over the center of the country. There was a weak disturbance moving across Texas to the south of the upper high pressure. At the surface, high pressure was centered just south of Grand Isle. Mid and high cloud cover were associated with the Texas disturbance, but were mainly to the west of Louisiana moving east.
The Texas disturbance will move across the local area late this afternoon and tonight. Considering the dry airmass, I don’t anticipate any precipitation, but cloud cover will increase late in the day. The question will be whether it arrives soon enough to stop temperatures from reaching forecast highs. Forecast soundings show high level moisture becoming significant enough to produce ceilings by mid to late afternoon, so there may not be much effect on high temperatures. Boundary layer temperatures remain little changed from Monday afternoon, so would expect similar highs for the most part. Cloud cover will likely keep morning lows Wednesday morning 3-5F warmer than this morning, especially over the northern half of the area.
High pressure off the Atlantic coast will hold the western trough over the Rockies Wednesday night and Thursday, providing a warm April day with most areas getting into the lower 80s. The western trough and associated cold front will move into the area at the end of the week, with the leading edge of any showers/storms potentially reaching the western portion of the area around sunrise on Friday. There are still some spatial and temporal differences between the global models. At this point, can`t take heavy rain threat or severe threat off the table, and we’ll continue to monitor.
Both global solutions have the trough and cold front well east of the local area by sunrise Saturday, ushering in much cooler and drier air for the remainder of the weekend.