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FXUS64 KMRX 030545 AFDMRX

Area Forecast Discussion National Weather Service Morristown TN 145 AM EDT Fri May 3 2024

New AVIATION

UPDATE
Issued at 825 PM EDT Thu May 2 2024

POPs were nudged up slightly in the southern Valley and southern Plateau late tonight into the early morning hours. Consshort and HRRR guidance is somewhat high in that area but CAMs have very spotty light activity, so I was hesitant to increase POPs much before sunrise. That was the only minor change to the forecast for tonight. Thunder potential is fairly low through sunrise but a few strikes will be possible. Expect increasing clouds overnight.

SHORT TERM
(This evening through Friday)
Issued at 306 PM EDT Thu May 2 2024

Key Messages:

1. Increasing chances for rain and storms tonight and into Friday.

2. While severe weather is not expected, a few instances of 1/4" hail and wind gusts up to 40 mph are possible tomorrow afternoon with any stronger storms.

Clouds increase tonight as high pressure shifts east due to a shortwave pushing in from the west. This shortwave will bring increasing chances of POPs, mainly after midnight. Precip most likely arrives onto the Cumberland Plateau somewhere around daybreak, then spreading further east into the east TN Valley through mid to late morning. From late morning into early afternoon we should see enough instability develop to produce a few scattered thunderstorms. Shear profiles remain very weak so no threat of severe weather. HRRR SBCAPE probabilities of 500 J/kg or greater is around 50%. This lines up with what the HRRR is showing for tomorrow afternoon with SBCAPE values ranging from 300 to 800 J/kg. 0-6km shear will generally be around 20kts, so perhaps just enough to produce some 1/4" sized hail with any stronger updrafts. Along with wind gusts up to 40 mph. Again, just garden variety thunderstorms. High temps will be a touch cooler tomorrow with the scattered showers and cloud cover around with highs in the upper 70s to low 80s.

LONG TERM
(Friday night through next Thursday)
Issued at 306 PM EDT Thu May 2 2024

Key Messages:

1. Near normal to above normal temperatures through the long term.

2. Unsettled pattern with chances for showers and thunderstorms each day of the long term. More diurnal pattern of convection last three days of the period Tuesday through Thursday next week.

Discussion:

Showers and a few storms will likely be ongoing at the start of the long term period as another shortwave rolls in from the west. By Saturday morning, the shortwave should be somewhere between western and middle TN. This wave will nearly be cutoff from the upper level flow and be a slow mover. Meaning, shower and storm chances remain on the high side through the day. While showers and a few storms will be in place Saturday morning, it looks like the highest chances occur Saturday afternoon. This is due to increasing instability and the shortwave pushing further east into our area. As with Friday, any stronger storms will have the ability to produce small hail and gusty winds but no severe threats are anticipated at this time due to weak shear.

On Sunday, this shortwave will still be impacting the area as it won't completely lift off to our northeast until Sunday evening.
This means another day of scattered showers and storms, though less coverage compared to Saturday. No severe threats, just garden variety storms.

On Monday, yet another shortwave rolls through. You guessed it, more chances for showers and storms. Tuesday through Thursday, a broad and deep upper trough sets up across the western and central U.S.
With high pressure to our south, this puts our region in quasi- zonal, southwesterly, flow pattern. During this time, shower and storm chances will be more diurnally driven. Also, stronger upper level winds are progged to move in from the west with the approach of the trough, which means higher shear. This will set the stage for an increase in severe weather chances. We remain too far out for much detail other than to keep an eye on the forecast in the coming days to see how next weeks' pattern evolves.

AVIATION
(06Z TAFS)
Issued at 139 AM EDT Fri May 3 2024

VFR conditions will be predominant through the TAF cycle, with mid to low level BKN/OVC clouds increasing through the morning into the afternoon. Continue to expect increasing rain chances near CHA and TYS this morning, with chances for a few thunderstorms by the afternoon. Rain chances increase late morning to mid-day at TRI, and have kept thunder omitted. Recent hi-resolution guidance suggest by late Friday evening activity becomes more isolated so have transitioned the mention of showers and storms to vicinity.

PRELIMINARY POINT TEMPS/POPS
Chattanooga Airport, TN 81 64 81 63 / 50 40 80 30 Knoxville McGhee Tyson Airport, TN 81 64 78 62 / 60 40 90 50 Oak Ridge, TN 81 63 78 62 / 60 50 80 40 Tri Cities Airport, TN 82 61 75 60 / 50 40 90 60

MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.

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