Air Resources Laboratory banner image
Air Resources Laboratory web site National Oceanic and Atmospheric Administration (NOAA)

tn discuss

Office: MEG

FXUS64 KMEG 212322 AAA

Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
622 PM CDT Sun Oct 21 2018

Updated for 00Z Aviation Forecast Discussion below.


.PREV DISCUSSION... /issued 325 PM CDT Sun Oct 21 2018/

DISCUSSION...Surface analysis this afternoon places a 1028 mb
ridge of high pressure over the Mid South. This has resulted in
sunny skies and cool temperatures in the 50s at most locations.
Frost/freeze potential late tonight into early Monday morning and
rain chances for the latter half of this week are the predominant
forecast challenges in this afternoon's forecast issuance.

The aforementioned ridge of high pressure overhead will result in
clear skies, light to nearly calm winds, and temperatures dropping
into the lower to middle 30s across many locations overnight into
early Monday morning. Current short term trends suggest
temperatures may reach between 30 to 32 degrees across portions of
West Tennessee near the Tennessee River and middle 30s across much
of the forecast area. Consequently, I've issued a Freeze Warning
for some locations near the Tennessee River and continued but
expanded the Frost Advisory to include more of Northeast
Mississippi and include the Memphis area. The evening shift will
continue to monitor trends and adjust hazards as needed if
conditions warrant any changes.

Otherwise, models indicate a ridge of high pressure will remain in
place across the Mid South through Wednesday resulting in mainly
precipitation free weather with highs in the 60s and lows mainly
in the 40s.

Long term models suggest an initial mid-level shortwave trough
will move through portions of the Middle/Lower Mississippi Valleys
late Wednesday night into Thursday and a reinforcing shortwave
trough Friday night into Saturday. Some model run to run
differences remain between the GFS and ECMWF and have kept rain
chances to a minimum until models come into better agreement.



00Z TAFs

Clear skies and light winds to prevail through the period, with
surface high pressure over the Midsouth.



AR...Frost Advisory from 3 AM to 9 AM CDT Monday for Clay-Craighead-
     Crittenden-Cross-Greene-Mississippi-Poinsett-St. Francis.

MO...Frost Advisory from 3 AM to 9 AM CDT Monday for Dunklin-Pemiscot.

MS...Frost Advisory from 3 AM to 9 AM CDT Monday for Alcorn-Benton MS-
     Calhoun-Chickasaw-DeSoto-Itawamba-Lafayette-Lee MS-Marshall-

TN...Frost Advisory from 3 AM to 9 AM CDT Monday for Chester-Crockett-

     Freeze Warning from 3 AM to 9 AM CDT Monday for Benton TN-



Office: OHX FXUS64 KOHX 212300 AFDOHX Area Forecast Discussion National Weather Service Nashville TN 600 PM CDT Sun Oct 21 2018 .UPDATE... FOR 00Z AVIATION DISCUSSION. && .DISCUSSION... Clear skies with cool, fall air -- and a bit of a breeze -- have settled into Middle TN this afternoon. The wind will die down in the next couple of hours and with the surface ridge axis over the state, we can expect Monday morning lows to be even colder than they were last night. A few hours of widespread freezing temperatures will be seen prior to sunrise. For this reason, the Freeze Warning for all of Middle TN will continue. Temperatures should recover back to the upper 30s by 8 am tomorrow. This CP air mass will push east of the state tomorrow and allow for some southerly flow to begin. This should allow us to warm into the mid 60s Monday and Tuesday. However, a dry, reinforcing frontal system due in here Tuesday afternoon will negate the continued warmup Wednesday. Our next chance of rain is a little muddled in the models right now. The GFS suggests it could be Saturday before we see any appreciable rain, whereas the latest Euro is progging rains move in by Thursday. With the inconsistencies, I'll just carry a small chance starting Thursday across the south, carry it through the weekend for now and adjust as models become clearer. If I had to pick a time frame right now for the best rain chances it looks like next Saturday night, but that is a week away. && .AVIATION... 00Z TAF DISCUSSION. VFR. Cirrus clouds will increase overnight into tomorrow but no low or mid level cloud cover is expected. Winds will be light or even calm tonight, but increase out of the southwest to 5-10 knots on Monday morning. && .OHX WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 3 AM to 8 AM CDT Monday for Bedford-Cannon- Cheatham-Clay-Coffee-Cumberland-Davidson-De Kalb-Dickson- Fentress-Giles-Grundy-Hickman-Houston-Humphreys-Jackson-Lawrence- Lewis-Macon-Marshall-Maury-Montgomery-Overton-Perry-Pickett- Putnam-Robertson-Rutherford-Smith-Stewart-Sumner-Trousdale-Van Buren-Warren-Wayne-White-Williamson-Wilson. && $$ DISCUSSION......Unger AVIATION........Shamburger
Office: MRX FXUS64 KMRX 211918 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 318 PM EDT Sun Oct 21 2018 .SHORT TERM...(Tonight and Monday)... A sunny afternoon across the Southern Appalchians with temperatures currently in the upper 40s to mid 50s. Current water vapor imagery indicates a large area of dry air in place across the Southeastern U.S. PW values are currently around 0.2-0.3 inches. At the surface, high pressure is located just to the northwest of the forecast area. This high pressure will move into the forecast area tonight. Radiational cooling conditions will setup tonight with clear skies, light winds, and surface high pressure. Temperatures at 850 mb will warm into the 5-7 degrees Celsius range tonight as weak low-level southwesterly flow develops late tonight. Due to this, expect the colder locations tonight will be in the sheltered valleys of northeast Tennessee and southwest Virginia where temperatures will drop down into the upper 20s to low 30s. Further to the south, expect frost in the central and southern valley with temperatures dropping down into the mid-30s with light winds. Temperatures will warm quickly on Monday with mostly sunny skies and weak warm air low level advection. Monday should be an excellent weather day for outdoor activities with sunny skies and highs in the 60s. .LONG TERM...(Monday night through Saturday)... Overall, not much change in the long term. Northwest flow briefly becoming more zonal Monday night but a weak and dry frontal passage on Tuesday will reestablish northwest flow across the area. Tuesday looks to be the warmest day of the period with highs in the mid to upper 60s. After the frontal passage on Tuesday night, colder air moves back into the region. Dry conditions but below normal temperatures expected Tuesday night through Thursday. Moisture begins to increase across the area Thursday/Thursday night and through Friday as a shortwave slides across to our south. There is still model disagreement on how far north the moisture makes it. The ECMWF continues to show the moisture up across our area while the GFS keeps it south. Because of the disagreement, continued with a slight chance and low-end chance POPS starting Thursday night. Then, a low pressure system quickly dives down into our area over the weekend and brings a better shot of precip. This system will bring additional cold air into the area just beyond this extended period. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 37 66 43 68 / 0 0 0 0 Knoxville McGhee Tyson Airport, TN 35 65 41 67 / 0 0 0 0 Oak Ridge, TN 35 65 40 68 / 0 0 0 0 Tri Cities Airport, TN 30 63 37 64 / 0 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...Freeze Warning from 2 AM to 9 AM EDT Monday for Cherokee-Clay. TN...Freeze Warning from 2 AM to 9 AM EDT Monday for Blount Smoky Mountains-Campbell-Claiborne-Cocke Smoky Mountains-East Polk-Grainger-Hamblen-Hancock-Hawkins-Jefferson-Johnson- Morgan-Northwest Carter-Northwest Cocke-Northwest Greene- Scott TN-Sevier Smoky Mountains-Southeast Carter-Southeast Greene-Southeast Monroe-Sullivan-Unicoi-Union-Washington TN. Frost Advisory from 2 AM EDT /1 AM CDT/ to 9 AM EDT /8 AM CDT/ Monday for Anderson-Bledsoe-Bradley-Hamilton-Knox-Loudon- Marion-McMinn-Meigs-NW Blount-North Sevier-Northwest Monroe- Rhea-Roane-Sequatchie-West Polk. VA...Freeze Warning from 2 AM to 9 AM EDT Monday for Lee-Russell- Scott-Washington-Wise. && $$ MA/SR