Thursday Weather Discussion

5/28/20


As of 2:30pm: Thunderstorms in progress across the Southern tier of the coverage area. These will move into the Eastern areas along and North of I-40 over the next hour. Nothing severe at this time and storms are having a tough time surviving. An additional line of showers is moving East along the I-40 corridor in McDowell County. The heaviest rain with this line is moving out of Spruce Pine and into North Cove. Conditions ahead of these two clusters are marginal for strengthening. Do expect lightning alerts to extend North to the I-40 corridor within the upcoming hour.


As of 1:15pm: Storm initiation is underway across the mountains and the SC Upstate. Radar and satellite indicate a line segment trying to organize across Northeast Georgia. Storm motion will be from south to north this afternoon. Instability values are probably peaking out for the day. Storms today will produce frequent lightning and gusty, isolated damaging winds.


As of 12:30pm: Water vapor satellite imagery indicates that the upper level low pressure is ejecting out of Arkansas into Northwest Mississippi. Ahead of it dry air at the mid levels coupled with left over low level moisture is producing atmospheric instability on the order of 2400 j/kg across the I-40 corridor and nearly 3000 j/kg. The cap that has been in place this morning is starting to erode so we expect thunderstorm activity to develop within the next two hours. Isolated damaging wind risk still will be the primary risk this afternoon. There is still an isolated risk of flash flooding as well.


7:00am 5/28/2020


Severe Risk Today; Marginal - Risk level 1 out of 5 (Damaging Wind Risk)

Flash Flood Risk Today: Marginal: Risk level 1 out of 4



Good Thursday Morning. Bertha has departed from our area to the Northwest and in its wake it leaves a broken cloud deck. As you head out the door expect mostly cloudy skies but there are some breaks where some will see some sunshine. As the sun gets up this morning we should lose a lot of this stratus layer. Today some areas will warm quicker than others but I think temps will generally be in the upper 70's to around 80° in the northern foothills and the low 80's in the southern foothills.


Low levels remain very moist in the wake of Bertha as mid levels start to dry out in response to increasing winds at the mid levels. This sets the stage for at least spotty convection over the region this afternoon. Thunderstorms should fire with temps in the mid 70's today and that looks most likely around the 2-6pm hour. Atmospheric moisture levels are up around 2 inches. Due to antecedent stream flows being above normal there could be some isolated flash flooding this afternoon. With those mid levels drying out CAPE will increase to 2000-2500 j/kg. Areas along the SC border may see CAPE values increase to 2500-300 j/kg. With the 30-40 knots of shear today storms may try to organize into small clusters. As an upper low approaches the area from the SW this afternoon a few clusters of storms may develop in Georgia and move north-northeast into the area. Today's severe weather risk will be damaging winds. A few isolated large hail events are possible where storms try to cluster together. All storms will produce frequent lightning and torrential rainfall. The only thing saving us from seeing a wider flash flood risk today is that those mid and upper level steering currents that will quickly move storms from south-southwest to north-northeast. That being said anywhere that happens to see repeated convection could see some localized flash flooding issues.


Marginal Risk (Green Shade) For Flash Flooding


Marginal Risk For Severe Weather Today


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