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

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000 FXUS64 KMRX 311845 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 245 PM EDT SUN MAY 31 2015 .SHORT TERM (THIS AFTERNOON THROUGH MONDAY)...A WEAK JET STREAK IS MOVING ACROSS THE AREA TODAY ENHANCING CONVECTION OVER AREA. A FRONTAL BOUNDARY IS MOVING SLOWLY SOUTH ACROSS CENTRAL KENTUCKY AND WESTERN HALF OF TENNESSEE. THIS BOUNDARY WILL APPROACH THE AREA OVERNIGHT. AIRMASS IS MODERATELY UNSTABLE WITH CAPES AROUND 1000 J/KG. MODELS SHOW SCATTERED TO NUMEROUS CONVECTION CONTINUING OVER THE REGION THROUGH THE EVENING HOURS...DIMINISHING IN COVERAGE OVERNIGHT. GIVEN PWS AROUND 1.5-1.6 INCHES AND FRONTAL BOUNDARY SLOWLY MOVING INTO THE AREA...TRAINING OF HEAVY RAINS ARE POSSIBLE WITH LOCALIZED FLASH FLOODING. BESIDES THE HEAVY RAIN...THE MAIN CONCERN THIS EVENING AND MONDAY AFTERNOON/EVENING WILL BE STRONG GUSTY WINDS UP TO 50 MPH... SMALL HAIL...HEAVY DOWNPOURS/LOCALIZED RUNOFF ISSUES...AND FREQUENT LIGHTNING. UPPER TROUGH OVER THE WESTERN TENNESSEE VALLEY WILL SLOWLY MOVE ACROSS THE REGION WITH PLENTY OF CLOUD COVER KEEPING TEMPERATURES DOWN FOR MONDAY. .LONG TERM (MONDAY NIGHT THROUGH SUNDAY)...SOMEWHAT OF A STAGNANT PATTERN THROUGH MOST OF THE LONGTERM DUE TO A CUT OFF UPPER LEVEL TROUGH. THIS PATTERN WILL ALLOW FOR CHANCES FOR CONVECTION EACH DAY. A FEW STRONG TO ISOLATED SEVERE STORMS WILL BE POSSIBLE MONDAY EVENING BUT STORM INTENSITY SHOULD QUICKLY FADE WITH THE SETTING SUN. A SATURATED MOISTURE PROFILE WITH HIGH PWS COULD RESULT IN SOME BRIEF HEAVY DOWNPOURS. WEAK FRONTAL BOUNDARY GRADUALLY BEGINNING TO MAKE AN EXIT MONDAY NIGHT BUT NOT MOVING ANYWHERE TOO FAST. THE FRONT FINALLY MOVES EAST OF THE APPALACHIAS BY LATE TUESDAY NIGHT. TUESDAY A CUT OFF UPPER LEVEL TROUGH WILL BE POSITIONED SOMEWHERE OVER THE SOUTHERN U.S. POSITIONING OF THE UPPER LEVEL TROUGH IS HARD TO PIN DOWN DUE TO IT`S WEAK AND BROAD NATURE. EXACT LOCATION OF THE TROUGH WILL HAVE AN IMPACT ON OUR PRECIP CHANCES. THE GFS WANTS TO KEEP THE TROUGH CENTERED FURTHER SOUTH WHICH GIVES US HIGHER PRECIP CHANCES DUE TO DEEPER MOISTURE BEING PULLED UP INTO OUR AREA. THE ECMWF SOLUTION STILL GIVES US PRECIP CHANCES BUT NOT AS HIGH BECAUSE IT KEEPS THE TROUGH CENTERED FURTHER NORTH...OVER OUR AREA. THIS NORTHERN TROUGH PLACEMENT KEEPS THE DEEPER MOISTER TO OUR EAST. OVERALL...TROUGH RESIDES SOMEWHERE ACROSS OUR REGION THROUGH AT LEAST FRIDAY...WHEN IT FINALLY DRIFTS OUT OF THE AREA. SO TUESDAY THROUGH FRIDAY THERE WILL BE CHANCES FOR SHOWERS AND THUNDERSTORMS EACH DAY. COVERAGE WILL DEPEND ON TROUGH LOCATION. STORMS LOOK TO BE THE GENERAL PULSE TYPE DURING THIS PERIOD DUE TO LACK OF SHEAR ASSOCIATED WITH WEAK AND BROAD TROUGH. MODELS IN DISAGREEMENT FOR SATURDAY AND SUNDAY. ECMWF TRIES TO BRING UPPER LEVEL RIDGING IN FROM THE WEST WHILE THE GFS BRINGS IN ANOTHER WEAK TROUGH AND LOW PRESSURE CENTER FROM OUT OF THE NORTH. WON`T GO INTO TOO MUCH DETAIL AT THIS TIME SINCE IT`S AT THE END OF THE LONG TERM AND MODELS AREN`T AGREEING YET. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 67 82 65 80 / 70 70 40 30 KNOXVILLE MCGHEE TYSON AIRPORT, TN 65 81 63 79 / 60 70 50 30 OAK RIDGE, TN 67 81 63 79 / 60 70 50 30 TRI CITIES AIRPORT, TN 62 83 62 77 / 50 70 60 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$

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