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

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000 FXUS64 KMRX 261910 AFDMRX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 310 PM EDT SAT JUL 26 2014 .SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)...QUIET WEATHER SHOULD LAST FOR MOST THE NIGHT...EXCEPT FOR SW VA LATE WHERE AN MCS COULD HOLD TOGETHER AND CLIP THAT AREA TOWARD DAYBREAK. THE STRONG WIND FIELDS AND SEVERAL FAVORABLE SEVERE WEATHER PARAMETERS FOR SUNDAY INTO SUNDAY NIGHT...MAKE ONE QUESTION THE LOW MOS PROBABILITIES FOR THOSE 2 PERIODS. THE GFS MODEL SOLUTION SEEMED QUITE REASONABLE TO ME...BUT EVEN THE GFS MOS POPS WERE LESS THAN 50 PERCENT FOR THIS EVENT. I OPTED TO KEEP SOME SWATHS OF LIKELY POPS GOING...ALTHO THE INITIAL LATE NIGHT CONVECTION SHOULD DISSIPATE...LEAVING A FEW HOURS FOR STRONG CONVECTION TO DEVELOP AT LEAST BY NOON OVER THE NRN PLATEAU AND SW VA. DON`T SEE WHY THIS NEW CONVECTION WOULDN`T THEN SWEEP ESE ACROSS THE BULK OF THE FORECAST AREA INTO SUNDAY EVENING. ACTUAL TIMING AND COVERAGE MAY ALSO BE AFFECTED BY POTENTIAL OUTFLOW BOUNDARIES FROM THE EARLY MORNING CONVECTION. MINOR CHANGES MADE TO THE POP AND WEATHER GRIDS TO BE MORE IN LINE WITH GFS MODEL SOLUTION...AS WELL AS TO MESH WITH NEIGHBORING NWS GRIDS. CLOSELY FOLLOWED THE GFS MOS MINS FOR BOTH NIGHTS...BUT THE HOT MAX TEMPS FROM GFS MOS FOR SUNDAY LOOKED SUSPECT. SEVERE WEATHER THREAT LOOKS FAVORABLE...AS ADVERTISED EARLIER. MIGHT SEE MORE HAIL THAN USUAL GIVEN THE COOLING MID LEVEL TEMPS AND OTHER SEVERE PARAMETERS. SHEAR AND HELICITY INCREASE AS WELL...SO CAN`T RULE ISOLATED TO A FEW TORNADOES. WEBINAR TODAY WITH GRAPHICS POSTED TO HIGHLIGHT THIS SEVERE THREAT...AND ALSO CONTINUED A MENTION OF SEVERE THREATS IN THE ZFP PRODUCT. .LONG TERM...(MONDAY THROUGH SATURDAY)...MUCH OF THE EXTENDED FORECAST ACTUALLY LOOKS MORE LIKE A WINTER TYPE PATTERN WITH A PERSISTENT EASTERN U.S. UPPER TROUGH WITH NEVER ENDING NORTHWEST FLOW AND PLENTY OF MOISTURE FOR THE PRODUCTION OF PRECIPITATION. THE PERIOD STARTS OUT ON MONDAY WITH THE EARLY DEPARTURE OF THE SYNOPTIC COLD FRONT POSSIBLY BRINGING A SHOWER TO SOUTHEAST TENNESSEE AND SOUTHWEST NORTH CAROLINA EARLY IN THE DAY. MOISTURE WRAPS BACK INTO THE SOUTHERN APPALACHIAN REGION DURING THE DAY MONDAY AND THIS TREND CONTINUES INTO TUESDAY WITH TWO TO THREE WEAK SHORT WAVELENGTH FEATURES BUILDING SOUTHEAST ACROSS THE CENTRAL AND SOUTHERN APPALACHIANS. KEPT SOME SLIGHT CHANCE POPS FOR SHOWERS AND A THUNDERSTORM GOING THROUGH TUESDAY...MAINLY FOR HIGHER TERRAIN AREAS OF SOUTHWEST VIRGINIA AND EASTERN TENNESSEE. WEDNESDAY AND MUCH OF THE AREA WILL REMAIN DRY ON THURSDAY. HOWEVER...HAD TO KEEP THE CHANCE FOR SHOWERS AND THUNDERSTORMS ALIVE FOR FRIDAY AND SATURDAY AS THE LONG WAVE TROUGH HOLDS ITS POSITION ACROSS THE EASTERN STATES AS A COUPLE OF RELATIVELY SIGNIFICANT SHORT WAVES BUILD THROUGH THE BASE OF THE TROUGH INTO THE FIRST HALF OF THE WEEKEND. OF COURSE TEMPERATURES WILL BE WELL BELOW NORMAL THROUGH THE EXTENDED. IT WILL BE SO COOL THAT IT WILL FEEL MORE LIKE EARLY FALL RATHER THAN THE PEAK OF SUMMER WARMTH. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 71 93 72 84 / 0 30 50 20 KNOXVILLE MCGHEE TYSON AIRPORT, TN 70 90 70 81 / 20 50 60 10 OAK RIDGE, TN 70 90 69 81 / 20 50 60 10 TRI CITIES AIRPORT, TN 66 89 66 78 / 30 60 60 20 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TG

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