624
FXUS64 KMRX 081753 AAC
AFDMRX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MORRISTOWN TN
153 PM EDT THU MAY 8 2025
..NEW AVIATION
UPDATE
ISSUED AT 937 AM EDT THU MAY 8 2025
OVERALL THE FORECAST IS IN DECENT SHAPE AND ONLY SOME ADJUSTMENTS
TO RAIN CHANCES WERE NEEDED, BASED ON CURRENT RADAR TRENDS.
REGIONAL RADAR IMAGERY SHOWS SOME SCATTERED STORMS ONGOING ACROSS
EASTERN KY THIS MORNING, ASSOCIATED WITH AN AREA OF FOCUSED
ISENTROPIC ASCENT WHICH WILL PUSH OFF TO THE EAST BY NOON. SOME OF
THESE HAVE BEEN DECENTLY TALL, WITH TOPS NEAR 35K FT AGL, AND ARE
LIKELY PRODUCING SOME SMALL HAIL AS THEY GO ALONG. DON'T EXPECT
THERE'S MUCH SEVERE POTENTIAL WITH THESE AS THE INSTABILITY ALOFT
DOESN'T LOOK TOO SUPPORTIVE OF SEVERE STORMS, BUT I WOULDN'T BE
SURPRISED TO SEE THESE STORMS CONTINUE TO SUPPORT SOME SMALL HAIL
AS THEY TRAVERSE OUR VIRGINIA COUNTIES OVER THE NEXT COUPLE OF
HOURS. LOOKING FURTHER SOUTHWEST, SOME MID LEVEL STRATOCU IS
EXPANDING ACROSS NORTHERN AL AND MS WHICH ALIGNS WELL WITH MODEL
DEPICTIONS OF A H3 JET STREAK THAT IS MOVING ENE TOWARDS THE
TENNESSEE VALLEY THIS MORNING. THAT INCREASING LIFT COMBINED WITH
DAYTIME HEATING SHOULD ALLOW FOR THE LOW CLOUDS ACROSS EAST TN TO
BEGIN TO RAPIDLY BREAK UP AS WE MOVE TOWARDS MIDDAY. SATELLITE
IMAGERY SHOWS THAT TREND UNDERWAY ALREADY. THAT BRINGS US TO
INSTABILITY AND PRECIP/STORM CHANCES FOR LATER TODAY. I UPDATED
POPS THROUGH THE MORNING TO REFLECT CURRENT TRENDS AND THE LAST
COUPLE OF RUNS OF THE HRRR, ALL OF WHICH DON'T SUPPORT MUCH IN
THE WAY OF RAIN CHANCES THROUGH MIDDAY OUTSIDE OF OUR VA COUNTIES.
DIDN'T MAKE MUCH IN THE WAY OF CHANGES TO THE AFTERNOON HOURS.
CURRENT MODEL GUIDANCE STILL SUPPORTS A RISK OF SEVERE STORMS AND
I DON'T THINK THE MESSAGE HAS REALLY CHANGED IN THAT REGARD. THE
ENVIRONMENT WILL BE SUPPORTIVE OF ORGANIZED CONVECTION, WITH
INSTABILITY AND SHEAR VALUES GIVING US A RISK OF LARGE HAIL (GOLF
BALL SIZED PERHAPS) AND DAMAGING WINDS. SEE THE SHORT TERM
SECTION FROM THIS MORNING'S AFD BELOW FOR MORE DETAILS ON THE
SEVERE THREATS.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 313 AM EDT THU MAY 8 2025
KEY MESSAGES:
1. STORMS WILL MOVE THROUGH THE REGION LATE THIS AFTERNOON INTO THE
EVENING HOURS.
2. SOME STORMS WILL LIKELY BE STRONG TO SEVERE WITH LARGE HAIL AS
THE GREATEST CONCERN, UP TO THE SIZE OF GOLF BALLS. LOCALIZED
DAMAGING WINDS ARE ALSO POSSIBLE.
DISCUSSION:
CURRENTLY EARLY THIS MORNING, A WEAKENING CLOSED LOW IS CENTERED
OVER MISSOURI WITH A FRONTAL BOUNDARY JUST SOUTH OF OUR REGION. A
WEAK AREA OF LOW PRESSURE IS ALSO CENTERED JUST SOUTHEAST OF THE
UPPER LOW. THROUGHOUT THE DAY, THE UPPER LOW WILL LIFT TOWARDS THE
OHIO RIVER VALLEY WITH THE WEAK SURFACE LOW FOLLOWING A SIMILAR
TREND. THIS WILL ALSO ALLOW PULL THE FRONTAL BOUNDARY NORTHWARD INTO
OUR AREA AS A WARM FRONT. THE COMBINATION OF SURFACE HEATING AND
HEIGHT FALLS WILL ENHANCE THE THERMODYNAMIC ENVIRONMENT. THIS IS
ESPECIALLY TRUE WITH INDICATIONS OF MLCAPE TO 1,500 J/KG OR MORE AND
MID-LEVEL LAPSE RATES AROUND 7 CELSIUS/KM. THE CAMS INDICATE
DEVELOPMENT BEING GENERALLY TO OUR NORTHWEST DURING THE AFTERNOON
WITH A PROGRESSION THROUGH OUR AREA AROUND 4 TO 9 PM. THIS TIMING
WILL ALLOW FOR FURTHER DESTABILIZATION.
WINDS WILL BE FAIRLY UNI-DIRECTIONAL THROUGH THE PROFILE AND WEAKER
IN THE LOWER LEVELS, BUT EFFECTIVE SHEAR OF 30 KTS OR GREATER IS
ALSO ANTICIPATED. THIS ENVIRONMENT WILL SUPPORT ORGANIZED CONVECTION
WITH SOME SUPERCELLS ALSO POSSIBLE. ON TOP OF THE OVERALL LAPSE
RATES AND INSTABILITY, WBZ HEIGHTS WILL BE BELOW 10,000 FEET AGL
WITH INDICATIONS THAT 50 DBZ RETURNS AT JUST 25,000 FEET AGL BEING
SUFFICIENT FOR 1 INCH HAIL. HAIL CAPE (-10 TO -30 CELSIUS REGION) IS
ALSO INDICATED TO SURPASS 600 J/KG. THIS REALLY UNDERSCORES THE HAIL
THREAT WITH GOLF BALL-SIZED REPORTS POSSIBLE. THE ORGANIZED NATURE
OF STORMS WILL ALSO SUPPORT A DAMAGING WIND THREAT AS WELL. WITH HOW
WEAK THE FLOW IS IN THE LOWER LEVELS, THE TORNADO THREAT IS LOW
OVERALL UNLESS SOMETHING WERE TO SPIN UP ALONG THE BOUNDARY ITSELF.
ACTIVITY IS EXPECTED TO DIMINISH ALONG SOUTHERN PORTIONS OF THE AREA
LATER IN THE NIGHT AS THE FRONT DRIFTS BACK SOUTHWARD. MORNING FOG
WILL BE POSSIBLE FOLLOWING THE RECENT RAINFALL.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 313 AM EDT THU MAY 8 2025
KEY MESSAGES:
1. FOR FRIDAY THROUGH SUNDAY, RAIN CHANCES WILL BE VERY LIMITED
OUTSIDE OF THE SOUTHERN HALF OF THE AREA.
2. BY NEXT WEEK, MORE WIDESPREAD RAINFALL IS LIKELY WITH STORMS
POSSIBLE TUESDAY AND WEDNESDAY.
FRIDAY THROUGH SUNDAY
AT THE START OF THE PERIOD, A CLOSED LOW WILL BE CENTERED OVER THE
EASTERN GREAT LAKES WITH ANOTHER CLOSED LOW DEVELOPING OVER
ARKANSAS. THE FRONTAL BOUNDARY FROM THE SHORT TERM PERIOD WILL BE
CENTERED JUST TO OUR SOUTH. THROUGHOUT THE DAY ON FRIDAY, THE CLOSED
LOW TO OUR SOUTHWEST WILL STRENGTHEN WITH THE FRONTAL BOUNDARY
DRIFTING FURTHER SOUTH AS HIGH PRESSURE EXPANDS FROM THE NORTH. THIS
WILL KEEP TEMPERATURES FAIRLY MILD WITH RAIN CHANCES FOCUSED IN
SOUTHERN PORTIONS OF THE AREA. BY SATURDAY, THE NORTHEASTERN CLOSED
LOW WILL BE TRACKING INTO NEW ENGLAND WITH THE SOUTHWESTERN ONE
DRIFTING TOWARDS THE NORTHWESTERN GULF. FURTHER EXPANSION OF HIGH
PRESSURE WILL SHIFT RAIN CHANCES EVEN MORE SOUTHWARD WITH MUCH OF
THE AREA LIKELY REMAINING DRY. BY SUNDAY, THE NORTHEASTERN CLOSED
LOW WILL HAVE LIFTED AWAY FROM THE U.S. WITH THE ONE TO OUR
SOUTHWEST EXPECTED TO DEEPEN. FOR SUNDAY ITSELF, CONTINUED HIGH
PRESSURE WILL KEEP MUCH OF THE NORTHERN HALF OF THE AREA DRY.
MONDAY THROUGH WEDNESDAY
BY EARLY NEXT WEEK, THE CLOSED LOW IS CURRENTLY FORECAST TO TRACK
NORTHWARD ALONG THE MISSISSIPPI RIVER VALLEY, WHICH WILL BRING A
RETURN OF MORE WIDESPREAD RAINFALL TO THE AREA. BY TUESDAY, WAA FROM
ITS PROGRESSION WILL LIKELY BRING INSTABILITY SUFFICIENT FOR
SCATTERED CONVECTION. BY WEDNESDAY, THIS CLOSED LOW WILL LIFT TO THE
NORTH WITH A DEEP TROUGH TO OUR NORTHWEST COMING INTO VIEW. THIS MAY
PROVIDE EVEN BETTER SUPPORT FOR ORGANIZED CONVECTION ACROSS A LARGE
AREA. CURRENTLY, ANALOGS ARE SHOWING AT LEAST LOW-END CHANCES FOR
STRONG TO SEVERE STORMS TUESDAY AND/OR WEDNESDAY, SO IT WILL BE
WORTH WATCHING.
AVIATION
(18Z TAFS)
ISSUED AT 146 PM EDT THU MAY 8 2025
HAVE HIGH CONFIDENCE IN FAIRLY HIGH COVERAGE OF TSRA ACROSS EAST
TENNESSEE LATE THIS AFTERNOON AND EVENING. RELATIVELY SPEAKING,
THE HIGHEST CONFIDENCE IS AT KTYS AND KTRI SO WILL GO WITH TEMPO
GROUPS THERE AND KEEP A PROB30 AT KCHA. AIR MASS STABILIZATION
TONIGHT COMBINED WITH RAINFALL SHOULD PRODUCE A FAIR AMOUNT OF FOG
AND LOW CLOUDS.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 81 58 77 55 / 50 40 20 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 79 57 73 51 / 70 70 20 0
OAK RIDGE, TN 78 56 74 50 / 70 60 10 0
TRI CITIES AIRPORT, TN 76 56 70 45 / 60 70 40 0
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...CD
LONG TERM....BW
AVIATION...CD
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