Sunrise 6:27 AM   Sunset 8:39 PM Moonrise 2:16 PM   Moonset 2:31 AM

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FXUS64 KMRX 172324 AAA AFDMRX

Area Forecast Discussion...UPDATED National Weather Service Morristown TN 724 PM EDT Fri May 17 2024

New AVIATION

SHORT TERM
(This evening through Saturday)
Issued at 315 PM EDT Fri May 17 2024

Key Messages:

1. Mostly light and isolated to scattered rain showers this afternoon and evening, with a relative lull in activity overnight.

2. Some fog development possible tonight but extent of coverage/density is a bit uncertain.

3. Additional showers and a few storms possible tomorrow. Isolated stronger storms could result in gusty winds and small hail.

Discussion:

Developing low pressure and a surface warm front remain in place along the Gulf states. A resulting precip shield has notably choked off moisture advection into the region, with light precipitation becoming more isolated to scattered within our forecast area. Light rain showers will continue to remain possible through the evening with a relative lull in activity expected overnight, though we may not stay totally dry. At this point, believe thunder chances are quite low. Additionally, given the low level moisture expect there to be some amount of fog/mist development over night. However, uncertainty exists as to how widespread or how dense this may become as low stratus clouds will promote poor radiational cooling and any light rain showers could result in brief mixing at times.

Additional activity is expected to develop tomorrow afternoon, especially in terrain influenced locations such as southwest Virgina, the Cumberland Plateau, and the East Tennessee mountains.
Recent model derived soundings suggest some some instability will build back into the region - generally 750-1250J/kg as the aforementioned warm front lifts into central Georgia. Lapse rates look to be meager, in the low 6C/km range. Believe thunder chances will be better tomorrow, though activity will generally remain scattered. It is possible that a few general thunderstorms develop and become on the stronger side with gusty winds of 40mph and small hail but think the severe threat is quite low. Considerations to take into account will be additional precip to our south potentially cutting off moisture once again and how long we remain socked in with low stratus/fog. Temperatures will remain mild trough the near term.

LONG TERM
(Saturday night through next Friday)
Issued at 315 PM EDT Fri May 17 2024

Key Messages:

1. Our wet weekend doesn't end until mid to late Sunday afternoon.

2. Drier on Monday and Tuesday.

3. Cold front to bring additional showers, and a few storms, into the area mid to late week.

Discussion:

We begin the period with a weak upper level trough and shortwave traversing across the area. Light and scattered showers will continue until mid to late Sunday afternoon. Then, precip comes to an end as upper riding builds in from the southwest and pushes the trough to the leeward side of the Appalachians.

Ridging further builds into the area and remains in place Monday through Tuesday. Conditions should be mostly dry with warmer temperatures. NBM wants to put in a few isolated showers and storms each afternoon. However, low confidence this actually occurs as there will be very little moisture to work with in the atmosphere under the northerly flow regime that will be in place.

As of now, our midweek system doesn't look very impressive. An area of strong high pressure to our south will really slow down the cold front as it approaches from the west. Also, the best dynamics still remain well north with the low all the way up into the Great Lakes/Canada. Models generally show precip moving into our area Wednesday afternoon into Thursday, along with a few storms but with no concerning severe threat as of now. Model solutions diverge past Thursday with varying solutions. NBM keeps POPs in on Friday behind the cold front but can't find a reason to remove them due to model uncertainty.

AVIATION
(00Z TAFS)
Issued at 721 PM EDT Fri May 17 2024

Low clouds are expected to be the main aviation impact at all sites through the night. Expect that as the moist boundary layer cools, cigs will drop to at least MVFR, possibly IFR or LIFR at times. Fog may develop as well but with overcast cigs in place, vis probably will not drop below MVFR, but confidence is low on this. A gradual rise in cigs is expected through tomorrow morning, followed by VFR cigs with scattered showers and thunderstorms in the afternoon.

PRELIMINARY POINT TEMPS/POPS
Chattanooga Airport, TN 73 66 80 63 / 60 20 70 40 Knoxville McGhee Tyson Airport, TN 73 63 76 62 / 50 40 70 60 Oak Ridge, TN 72 62 77 62 / 60 40 70 50 Tri Cities Airport, TN 73 60 75 60 / 70 60 70 60

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

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