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

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000 FXUS64 KMRX 170754 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 254 AM EST Fri Feb 17 2017 .SHORT TERM (Today and Tonight)...
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Temperatures this morning are the coldest forecast over the next 7 days. Expect values in the mid 20s to mid 30s by daybreak this morning. Current water vapor imagery and RAP upper air analysis indicates a shortwave trough moving southeast across the Great Lakes. This shortwave will bring an increase in clouds later this morning to Northeast Tennessee and Southwest Virginia but no precipitation is expected with the lack of moisture. A ridge extends from the Northern Gulf of Mexico northwards to the Northern Plains. A closed low is currently spinning across Texas and will impact the weather just beyond the short-term forecast period. At the surface, a ridge of high pressure stretches from the Northern Gulf Coast into the Great Lakes region. Southwesterly winds will develop today as the surface ridge shifts to the east. Increasing heights aloft and an ample supply of insolation will lead to highs in the upper 50s to mid 60s this afternoon. The closed low currently across Texas will transitions into an open wave and track to the northeast into the Mid-Mississippi River Valley by late tonight. Model soundings indicate saturation developing in the mid to upper levels late in the forecast period with PW values increasing into the 0.7-0.9 inch range by early Saturday morning across the western half of the forecast area. Latest model trends indicate precip. starting around 12z Saturday morning and have left the short-term forecast dry for now. Cloud cover will increase tonight with lows in the mid 30s to mid 40s. .LONG TERM (Saturday through Thursday)... A low pressure system will track northeast across the Southern Appalachian Region on Saturday and Saturday night. Scattered showers will accompany the low spreading rain across the MRX CWA. Temperature profile looks warm enough for an all rain event. A ridge of high pressure builds in on Sunday through Monday night for dry conditions and above normal temperatures. Model consistency becomes quite poor by Tuesday and confidence is low. The GFS model shows a more active weather pattern through the rest of the extended with a cold front moving into the area late Tuesday/Tuesday evening...then a low pressure system tracking through along the gulf on Wednesday...and a weak short wave on Thursday. The ECMWF is slower with the cold front...bringing it in Tuesday night into Wednesday with weak ridging for Thursday. For now will compromise between the two with the best chance of pops Tuesday night into Wednesday and a mix of 20 to 30 pops through the rest of the extended. With a warm air mass in place...expect generally rain thorugh the period.
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&& .PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 67 45 59 45 / 0 10 50 20 Knoxville McGhee Tyson Airport, TN 64 42 59 44 / 0 0 40 30 Oak Ridge, TN 65 41 59 44 / 0 0 40 30 Tri Cities Airport, TN 62 37 57 43 / 0 0 40 40
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&& .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ MA/MJB

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