Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS64 KMRX 181728 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 128 PM EDT Mon Mar 18 2024 ...New AVIATION... .UPDATE... Issued at 1144 AM EDT Mon Mar 18 2024 Observations this morning were running a little warm against the forecast, but did not want to make much changes to the max temperature since expect temperatures today will struggle with the cold airmass moving across. Dewpoints are running pretty close to the forecast, so just blended in observations and smoothed the hourly forecast out. A special weather statement was issued area wide earlier this morning for fire danger today, breezy winds especially this afternoon combined with the low relative humidities means outdoor burning is strongly discouraged. && .SHORT TERM... (Today and tonight) Issued at 340 AM EDT Mon Mar 18 2024 Key Messages: 1. Cold weather arrives today and with cold air advection. Temperatures will be 10 to 15 degrees below normal. Winds from the northwest 15 to 25 mph with higher gusts to 35 mph at times this afternoon and evening. 2. Wind chills will be significant tonight and Tuesday morning. The wind chill values will be from 15 to 25 lower elevations and from zero to 10 degrees across the higher elevations of the eastern Tennessee mountains. Discussion: The stronger cold air advection has lagged behind the cold front that is now made it well into the Carolinas to around Raleigh to Charlotte NC and south of Atlanta early this morning. Temperatures have dropped into the 40s lower elevations and 30s higher elevations at this time. The airmass behind the front is very dry and skies are partly cloudy to clear. Some locations will be near freezing tonight where winds decrease but frost formation is expected to be limited. Right now dewpoint depressions are still 10 to 20 degrees. Northwest flow looks to strengthen this afternoon, bringing stronger winds to east Tennessee and southwest Virginia. This will happen as the deepening upper trough moves into the region. Precipitable water values are forecast to be around 0.20" across all of East Tennessee and southwest Virginia which is near a daily minimum for this time of year. So with this happening afternoon relative humidities will dip to around 25 to 35 percent area wide. This will give fire weather concerns with the strong wind gusts. Some cloud cover is expected across the northern sections of the area late today with the deepening trough which may keep relative humidity values higher there. Will be deciding on a Special Weather Statement for Fire Weather for TN and NC this morning. Monday night and early Tuesday morning the coldest air settles southward into the Tennessee valley and southern Appalachians with a hard freeze across much of the area. With the continued cold air advection although winds will be decreasing, the dry airmass will limit frost development. The main impacts will be low wind chills below 20 degrees lower elevations and below 10 degrees in the higher elevations above 3000 feet across the higher mountains. && .LONG TERM... (Tuesday through Sunday)... Issued at 248 AM EDT Mon Mar 18 2024 Key Messages: 1. Low RH values with gusty winds will pose fire weather concerns on Tuesday afternoon. 2. Dry conditions continue but with warmer temperatures Wednesday and Thursday. 3. Rain chances return Friday. Discussion: On Tuesday a low pressure system will be over the Great Lakes, with high pressure over LA. Aloft, a dry NW flow pattern will continue with a trough off the East Coast. The surface pressure gradient will likely create a SW wind of 10-20 mph with gusts of 25-30 mph. The dry air mass in place and afternoon mixing will lower min RH values to 20-30%. For now, these conditions will be headlined in the FWF, although a Red Flag Warning may be needed with later forecast issuances. On Wednesday a dry frontal passage will occur, shifting winds to a more westerly direction. Breezy conditions with RH values in the 25- 35% range will likely continue. As high pressure builds in from the northwest Wednesday night, colder air will advect in behind the front. Lows in the 30s to upper 20s north are expected Thursday morning. Low RH values continue Thursday afternoon, although winds should be lighter. A southern stream shortwave trough will approach the area Thursday night, and cross the area Friday. Chance PoPs will be forecast for this period, with light QPF. Beyond this period, forecast confidence is low as the models diverge in their solutions for the weekend. Will have dry conditions Saturday and Sunday with temperatures near to slightly above normal. && .AVIATION...
-- Changed Discussion --
(18Z TAFS) Issued at 117 PM EDT Mon Mar 18 2024 VFR conditions are expected to continue through the TAF period. Scattered midlevel cumulus field will continue to build this afternoon before clearing out overnight. Breezy winds with gusts to 20 knots expected periodically this afternoon, winds will weaken tonight before pivoting to more westerly or west- southwesterly flow tomorrow.
-- End Changed Discussion --
&& .PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Chattanooga Airport, TN 29 57 39 69 / 0 0 0 0 Knoxville McGhee Tyson Airport, TN 27 55 38 66 / 0 0 0 0 Oak Ridge, TN 27 56 36 67 / 0 0 0 0 Tri Cities Airport, TN 25 53 36 63 / 0 0 0 0
-- End Changed Discussion --
&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...Wellington LONG TERM....DGS AVIATION...Wellington

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.