Today the squall lines marched across Mississippi. All of this stormyness was in the warm moist air a few hundred miles ahead of a cold front. Even at 12Z (7:00 AM) this morning, the upper air soundings were showing unstable air across the region, with CAPE of 666 J/kg at Jackson and 1375 at Shreveport (which was already near the squall line). The severe winds of the squall line came through the Jackson Metro area around 12:30 this afternoon, resulting in widespread damage. The ASOS at Hawkins Field in Jackson recorded the following report of 47 kt wind gusts before apparently losing power:
KHKS 041729Z 28035G47KT 1 1/4SM HZ SQ FEW036 BKN046 BKN070 24/17 A2994 RMK AO2 PK WND 26047/1728 PRESRR P0002
Earlier this morning, the surface charts provided a good example of potential problems in frontal analysis due to squall lines, outflow boundaries, and rain-cooled air.
For the most part, the fronts and air masses are easily identified in the RUC Theta-e analysis, including the relict cool air mass to the east of the Appalachians. The important point to note is that the low Theta-e air mass extending from northern Louisiana to Ohio is due to low-level rain-cooled air behind the squall line.
In east-central Texas the visible satellite imagery showed a dramatic shadow from the anvil of a complex of severe storms. Overshooting tops were also fairly pronounced in the morning sunlight.
Here is the radar reflectivity showing the squall line approaching Jackson:
And a close-up of the Doppler velocity just before the strongest winds reached JSU, showing storm-relative winds in excess of 50 kt:
1 comment:
It was a bit scary when the tornado sirens started going off. Glad everyone is okay.
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