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

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609 FXUS64 KMRX 221838 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 238 PM EDT Wed Mar 22 2017 .SHORT TERM...(Tonight and Thursday)...Surface high pressure over the Great Lakes Region will shift east and southeast, as the upper ridge to our west edges east. Flow over our area will turn more southerly, allowing some moisture return. Expect an increase in clouds overnight, then expect some decrease in clouds again during day Thursday. Biggest question will be need for any freeze warnings or frost advisories tonight. Right now appears portions of Northeast TN and Southwest VA that are in the freeze program will get cold enough before clouds move in to warrant a freeze warning. Will not include frost further south as expect too much cloud cover and in many areas a light wind will be stirring. .LONG TERM...(Thursday night through Tuesday night)...Thursday night through Saturday morning...High pressure off the east coast will continue to move out in to the Atlantic. At the same time...a low pressure system over the Great Plains will approach the mid MS Valley. Our area being between the high and low pressure...SW flow will increase beginning Friday morning...bringing an increase in warm and moist air advection. Temperatures Friday and Saturday will be several degrees warmer than normal...and cloud cover will increase along with the moisture advection. Saturday afternoon through Sunday afternoon...the low pressure will begin a sharp N to NE climb towards the Great Lakes with another low pressure system and associated trough developing in its wake. A boundary that approaches the area Saturday afternoon will cause scattered showers and thunderstorms to develop in areas generally south of I40...moving to the north. Instability is low and winds will be fairly unidirectional and gusty through the midlevels. PW values are above normal for this time of year...especially in areas south of I40. With the atmospheric profile...not expecting any severe threats to be low. However...gusty winds and flooding rains could be a concern...especially with the flow moving parallel to the boundary...storms could easily train over the same area causing the flooding. Sunday night through Tuesday night...The low pressure will move off to the NE...with only a slight chance for light scattered lingering showers over NE TN and SW VA through Sunday night. Behind the low pressure...flow continues from the S and SW...with the moisture and warm air advection continuing. Temperatures will remain several degrees above normal. The next low pressure system and associated trough will move through the area Monday afternoon through Tuesday night...keeping scattered showers over the area each period. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 42 64 47 68 / 0 10 10 10 Knoxville McGhee Tyson Airport, TN 39 60 43 66 / 0 0 0 10 Oak Ridge, TN 37 61 44 66 / 0 0 10 10 Tri Cities Airport, TN 29 59 39 66 / 0 0 0 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...Freeze Warning from midnight tonight to 10 AM EDT Thursday for Hancock-Hawkins-Northwest Carter-Northwest Greene-Sullivan- Washington TN. VA...Freeze Warning from midnight tonight to 10 AM EDT Thursday for Lee-Scott-Washington. && $$ LW/JW is the U.S. government's official web portal to all federal, state and local government web resources and services.