POSTED: Friday, May 1, 2009 20:37

This is a heads up on what is shaping up to be a potentially nasty weekend.   As a result, I will send out email updates often and will go ahead and schedule at least 1 conference call/webinar for Sunday morning at 9 AM. I’ve also attached some graphics that Mary Mayeaux (forecaster from our office) has put together discussing both the flood threat and severe threat this weekend.

 

Synopsis:  A cold front which has plagued us and the folks along the I-40 corridor this week is on the move finally…but not very quickly.  This front is forecast to move ever so slightly southward overnight tonight and stall in the I-30/I-40 corridor during the day tomorrow.  A potent upper level disturbance is forecast to move toward us on Saturday and across the region during the day on Sunday.  The low level jet is expected to respond by increasing to up around 50 kts by Sunday midday across Deep East Texas and Western LA.    Because it’s May (instead of March), instability will be much higher with this system which combined with wind shear will give us a much higher wind and tornado threat on Sunday.  Also, dewpoints are already in the upper 60’s to low 70’s areawide and model forecasts of total atmospheric moisture are expected to approach 200% of normal during the day Saturday through Sunday.  This combined with the instability will leave us with the possibility of Hail, Damaging winds and flooding Saturday into Sunday morning and all of the above plus tornadoes on Sunday.

 

Timeline:

Saturday:  Storms should be ongoing early in the morning across Oklahoma and Central Arkansas along the frontal boundary which should be along or south of the I-40 corridor.  If the front sags a little further south, then areas north of I-30 would have a greater chance of seeing storms throughout Saturday..which also increases the chances for flooding.  Daytime heating and enough upper level support will aid in strong to some severe storms on Saturday especially in these areas.  Some storms will also be possible further south down to I-20…but the severe threat is limited.

 

Saturday night: the influence of more favorable upper dynamics should start to be felt along and ahead of the front in the I-30 corridor as showers and storms increase in coverage.  Flooding may become an issue given the recent rains and saturated grounds.  We will be evaluating the possibility of a flood watch for Saturday night through Sunday.  The greatest risk for severe storms appears in McCurtain county and possibly spilling over into Little River, Sevier and Howard Counties.

 

Sunday:  The big day where severe weather will be possible area wide..with greatest risk east of a Broken Bow-Tyler line.  The upper level short wave will be moving across us/just north…at the same time a surface low will develop in East Texas and ride northeastward along the slow moving front.  The surface low will aid in enhancing low level shear values at the same time the upper level system will aid in destabilizing the atmosphere.  Currently, SPC has placed the region in a slight risk, but don’t be surprised if that goes up given the shear and instability available on Sunday.  The only fly in the ointment will be any showers or cloud cover that could inhibit instability (but that is always hard to predict at this stage in the game).    Heavy rains along the front and near the track of the surface low will also be possible during the day Sunday with some areas receiving over 5 inches possibly before a line of storms develops and moves across the area Sunday night.   Farmers and ranchers in low lying areas especially along the Red River north of I-20 may want to consider moving cattle given the Forecast along the Red River at and the rainfall in the forecast.

 

 

Spotters:  Please follow the Hazardous Weather Outlook for activation locations and times.   Preliminarily, spotters may be needed in the I-30 corridor tomorrow night and area wide on Sunday….Starting early in day Sunday in Texas to late afternoon from El Dorado through Monroe and Jena.  Timing this far out is tricky, but hopefully we can refine it some as the event gets closer.