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

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032 FXUS64 KMRX 180756 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 256 AM EST Sat Feb 18 2017 .SHORT TERM (Today and Tonight)... Temperatures this morning are the coldest expected throughout the forecast period. Some of the cooler valleys will start off in the mid to upper 30s with most locations in the 40s. The main feature in the short-term forecast will be the closed low currently located near Texarkana. Current water vapor imagery indicates moisture being pulled northward with this system from the Gulf of Mexico into the Lower Mississippi and Tennessee River Valleys. An upper level ridge exists just ahead of the advancing closed low stretching from the Florida Peninsula northwestward into the Ohio River Valley. At the surface, high pressure is now over the Atlantic with southerly flow across the area in the low levels. PW values will increase throughout the morning as moisture advects into the area. Model soundings indicate that the atmosphere will saturate from the top down as the upper low moves closer. Widespread light showers are forecast today as the system moves in. Rainfall amounts should be light with amounts ranging from 0.10-0.25 inches. Widespread cloud cover and precipitation will keep temperatures in the 50s throughout much of the day. Due to this, went on the lower side of guidance. The closed low will transition into an open wave late in the short-term period over the Mid-Atlantic. A ridge will build in quickly behind the departing system. Northwesterly flow will keep precip. chances in for the higher elevations early Sunday morning. .LONG TERM (Sunday through Friday)... A few showers may linger over far northeastern locations early Sunday morning as Saturday`s system exits the area. Otherwise...the extended begins in a quiet weather pattern as a high pressure ridge builds into the eastern U.S. This will result in dry and seasonally warm conditions for Sunday and Monday. For the rest of the extended...model and run consistency remains quite poor. The GFS is faster and wetter with the approach of a cold front...progging it into the region Tuesday into Tuesday night. The ECMWF is slower with the feature...bringing it through Tuesday night into Wednesday and trending towards a weakening frontal passage. For Thursday...the GFS has fairly zonal flow in place with a weak impulse moving through then brings low pressure system in around the Friday time frame. The ECMWF for the same period shows weak ridging for Thursday with a system approaching but not quite reaching into the area for Friday. With overall confidence low...will make little in the way of changes to the current forecast and continue with a strong chance pops for Tuesday night and Wednesday...low pops Thursday with increased chances for Friday. As for temperatures...will remain in a warm pattern with above seasonal temperatures throughout. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 61 45 70 46 / 60 10 10 0 Knoxville McGhee Tyson Airport, TN 59 46 67 44 / 40 30 10 0 Oak Ridge, TN 58 46 67 44 / 40 30 10 0 Tri Cities Airport, TN 59 44 64 42 / 50 50 10 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ MA/MJB

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