Chase forecast update 7, for April 26
As next week comes into clearer focus on the GFS and Euro models, my enthusiasm for a chase trip has waned. The return of southwest upper flow and low-level moisture to the Plains means severe weather and tornadoes are likely, but not always chaseworthy ones. Negative number one is that the individual day's setups are shown mostly in far southern Oklahoma near the Red River or farther south into Texas. Limited roads and more difficult storm observing terrain makes this an area I'm less likely to be happy about chasing in. I want a setup of stellar quality to be present before I look to start heading down there - and that brings me to negative two: the chase setups as they're shown right now aren't close to being stellar.
At Tuesday's favored "dryline bulge" target (this time in southwest Oklahoma), the GFS shows veered 850mb flow, barely-southerly surface winds, only moderately-favorable lapse rates, the main upper jet streak departing the area early in the day and widespread convection breaking out in the morning. The Euro is similar, showing a huge moisture-scouring thunderstorm complex roaring through the area in the morning, shunting the moisture southeast away from the area with little time for afternoon recovery. Wednesday looks equally messy, with continued early-day storms and only a weakly-unstable dryline play in west Texas.
On top of all this, a Midwest warm front will be in place right here at home, with essentially equal tornado chances as the Plains triple point. Since my standard protocol is to stay home if a favorable supercell/tornado threat exists here, at this point a Plains expedition next week is looking less likely.
Beyond the midweek setups, a cold front is shown pushing moisture back into the southern Gulf of Mexico - a "Gulf scouring front" as we call it. This will require an extended recovery period before the Plains can see quality moisture again. The good news is that extended-range data still leans toward an active mid-May, so we'll have to wait and see what that brings.
The following table charts the probabilities for a Plains chase expedition taking place for the date ranges shown:
|2019 Plains Chase Expeditions - Probabilities as of April 26|
|April 30-May 5||25%|