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FXUS62 KFFC 070523 AFDFFC

Area Forecast Discussion National Weather Service Peachtree City GA 123 AM EDT Tue May 7 2024

New 06Z Aviation Discussion

SHORT TERM
(This afternoon through Tuesday)
Issued at 251 PM EDT Mon May 6 2024

Notable shortwave is currently traversing the southeastern CONUS with remnant outflow boundary from this morning's convection stationed over northern GA. Deep layer moisture is punching in ahead of the shortwave in a region of strong PVA across northern and eastern GA, allowing for some steepening lapse rates under a region of broad ascent with the afternoon sunshine. Isolated storms are already firing across northern GA with some focus along the terrain, though so far these are certainly feeling our somewhat worked over environment aloft and haven't lasted too long, despite 15-25 kts of bulk shear analyzed on the SPC mesoanalysis. A more impressive storm is going in Jefferson County where a differential heating boundary is likely aiding in convective initiation. Expect isolated storms to continue through the evening hours, with slightly higher coverage possible in parts of northern GA. A Marginal (1 out of 5) risk has been issued for northern GA. The primary threats are isolated large hail and damaging winds.
Continued afternoon heating will allow for MLCAPE values to rise into the 1500-2000 J/kg range, which combined with effective bulk shear values of 20-25 kts as the shortwave continues to move through should allow for a few storms that could become more organized. The tornado threat isn't zero, but it is very low - overall forecast soundings show that low level shear struggles to be streamwise in nature, so a mesoscale accident along a boundary would likely be necessary.

Tonight, the shortwave is expected to move by and this should help suppress the continuation of any convection as region of AVA moves in and shortwave ridging builds. Concerns tonight will be how much rain falls today and how much clearing occurs to allow for some potential vsby and low ceiling issues. Currently have kept any haze or fog out of the forecast, but this could change tonight.

Tomorrow, the shortwave ridging is expected to remain in place over the area during the morning hours ahead of the next system ejecting out of the Plains. This should help keep things in check as far as convection goes for part of the day. However, strong jet streak within an elongating jet over the CONUS will move to the NW of the area, driving height falls and push a cold front/convective outflow into the SE during the afternoon. Some hires guidance redevelops convection along this and pushes into NW GA by the evening hours. This seems like a realistic scenario, though it will certainly be impacted in part by the convective evolution with the Great Plains this afternoon and tonight.
Diabatic pumping of the downstream ridge combined with the strong PV gradient along the jet/jet streak is leading to multiple rossby wave breaks, which is known to be a struggle for models to properly capture.

PoP chances have been concentrated over northern GA as a result of all this, with a Marginal Risk (1 out of 5) currently in place. A tongue of instability will creep into portions of northern GA with HRRR showing means of 1500-2000 J/kg of CAPE by the afternoon. Best shear is currently forecast to remain just to the NW of the region, but organized convection may find its way into NW GA as the evening progresses that may be able to squeeze out some severe wind or hail before becoming more disorganized.

Highs today will be in the 80s with lows overnight in the 60s across the CWA Tomorrow, highs will be in the 80s with even a few 90s possible in portions of central GA.

Lusk

LONG TERM
(Wednesday morning through next Sunday)
Issued at 251 PM EDT Mon May 6 2024

The start of the long term forecast period is quite busy as the upper level ridging gives way to a series of disturbances rounding a strong upper level low over the northern Plains/Great Lakes Region through Friday. As a result, several rounds of active weather with the potential for strong to severe storms is expected through the end of the work week. Wednesday, a stationary boundary will be draped to our north over the Ohio River Valley. As the first shortwave traverses eastward over the northern Plains, a mesoscale convective system is expected to take aim for locations north of the I-20 corridor Wednesday afternoon into the overnight hours.
Depending on the strength of the cold pool, the line of storms may hold on through Thursday morning. At this juncture, SPC has included locations across our far north in a Slight Risk (Level 2 out of 5)
and locations further south to the I-20 corridor in a Marginal Risk (Level 1 out of 5) for severe weather. With bulk shear between 40-50 KT and elevated mid level lapse rates through the overnight hours exceeding 7 C/km, the primary hazards with these storms will be damaging wind gusts and hail up to 1 inch. The next round of strong to severe thunderstorms will be associated with the upper level low progressing over the Great Lakes Region and the aforementioned boundary sagging southward towards our forecast area. At this time, SBCAPE is forecast to be running between 1000-2500+ J/kg, bulk shear between 35-50 KT, and lapse rates between 6-7+ C/km through the afternoon Thursday into Friday. For now, SPC has placed much of north and central Georgia into a 15% probability for severe weather Thursday through Friday morning. The primary hazards in storms would be damaging wind gusts and 1 inch hail (though there is a chance for hail stones to be larger should storms fire across south central Georgia where there is a swath of higher lapse rates around the 8 C/km mark progged). While the risk for flash flooding and river flooding is low at this time, locations across north Georgia could see as much as 2 to 2.5" of rainfall over the next 5 days where locally higher amounts are possible.

While the current trends signal the potential for severe weather through the first half of the forecast period, it is important to note that there is some uncertainty in the overall synoptic pattern moving forward. Additionally, the severe weather threat each day may be limited by any ongoing convection that could inhibit recovery and destabilization. Unfortunately these systems are often notoriously difficult to forecast this far out. We will be closely monitoring how the forecast evolves in the coming days with respect to our severe weather threat. Beyond Friday, we will transition into quasi- zonal flow where drier conditions are anticipated.

KAL

AVIATION
(06Z TAFS)
Issued at 100 AM EDT Tue May 7 2024

VFR through today and this evening. Some patchy few/sct MVFR possible towards morning. Winds will remain on the west side, with speeds around 10-12kt during the afternoon. Some low end gusts are possible. Low clouds will be possible towards 12Z WED. Pops too low to mention at this time.

//ATL Confidence
06Z Update
Med-high confidence all elements.

NListemaa

PRELIMINARY POINT TEMPS/POPS
Athens 68 88 68 83 / 20 40 30 80 Atlanta 69 88 70 83 / 30 40 40 90 Blairsville 64 82 63 77 / 40 40 70 90 Cartersville 66 88 66 83 / 40 40 50 90 Columbus 69 92 71 87 / 10 20 10 70 Gainesville 69 87 69 81 / 40 40 50 90 Macon 69 91 70 87 / 10 20 10 70 Rome 67 88 68 85 / 50 40 60 90 Peachtree City 68 89 69 85 / 20 30 30 80 Vidalia 69 93 70 92 / 10 10 10 50

FFC WATCHES/WARNINGS/ADVISORIES
None.

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