Bad Storms Wed. Night; 2 Cold Spells

Much to discuss. Tomorrow night’s thunderstorms could pack a punch. Normally, the severe stuff - high winds, tornadoes stay north of here from Natchez to Hattiesburg, but this one could be the exception.

This ECMWF forecast for tomorrow evening explains why. An upper level trough (centered around the green dash line) lies just west of here. Often, these troughs go north of here during the spring, but not this one. It will provide upper level wind divergence (notice the green arrows) which will help thunderstorm updrafts. The blue line represents the cold front and the black arrow shows the moist inflow off the Gulf. In short, most of the ingredients are in place.

Though there will be a few light showers during the day, the bad storms will wait until after 10 PM at night (perhaps as late as 5 AM Thursday). No one knows exactly who will bear the brunt of the storms, so keep your phone or weather radio handy to experience “Sleep us Interrupt us”. I can see widespread rains of about an inch from this.

Read on for details and for more information on two brief cold spells.

The Foreca graphic clearly shows the roller coaster temperatures we’ll experience in the next week. Tomorrow’s high of 83 will be followed by a windy, cooler, much less humid Thursday and a chilly 42 on Friday. Sunday’s 81 will be followed by a brisk and windy 61 on Monday and downright cold 39 on Tuesday morning. This ECMWF forecast for Tuesday morning shows the reason for the cold: A deep upper trough (and a strong surface low over the Great Lakes) will move cold Canadian air into the Ohio Valley and Upper South. Though there is some disagreement between with the warmer ECMWF and the colder American GFS, the key to avoiding a frost in rural areas is keeping the heart of the surface high away from us and the winds up. Tuesday’s morning’s winds are coming in at a stout 7-9 mph, so this doesn’t look likely. Wednesday’s winds are lighter, but the core of the cold will be away from us.

The good news in all of this is the mostly sunny weather we’ll experience starting on Thursday. The only chance of a shower is Monday morning with before the next cold front.

Here’s the next six days from the ECMWF showing quite a recovery in temperatures. Weather should remain mostly rain free through this period.