NE Alabama
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Severe March 13-15 Central Upper South Severe Threat
- Thread starter Webberweather53
- Start date
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- Tags
- severe weather
NE Alabama
RAP sounding for South East TN
Threat continues to increase
Worse then above. Dangerous
THIS SOUNDING IS FROM "LITERALLY" MY ROOF TOP
These storms/supercells that fire up before linear convection dominates needs to be watched, it’s a short window but anything that fires up discrete would likely be more dangerous, that moist layer from sfc-just above 700 hPa can really aid in the development of tornadoes, 3CAPE is ehh but enough in this sounding, that’s also one heck of a dry layer around 500 hPa
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
425 PM CDT WED MAR 13 2019
.SHORT TERM...
THROUGH TONIGHT.
AND SEVERE CHANGES...
WE WILL BEGIN TO SEE SMALL RAIN CHANCES RETURN AS EARLY AS THIS
EVENING IN THE FAR WEST. BETTER RAIN CHANCES WILL BEGIN TO SLOWLY
NUDGE INTO THE WEST/NORTHWEST AFTER MIDNIGHT. AS FOR TEMPERATURES,
WE WILL BE VERY MILD TONIGHT AS WARM ADVECTION FROM THE GULF OF
MEXICO STREAMS INTO THE STATE. OUR LOWS TONIGHT WILL BE WELL ABOVE
NORMAL AND HIGHER THAN OUR EXPECTED HIGHS FOR MOST OF FRIDAY. WINDS
WILL REMAIN UP WITH TIGHT SURFACE PRESSURE GRADIENTS BETWEEN OUR
TWO AIRMASSES. WE SHOULD REMAIN BELOW WIND ADVISORY CRITERIA FOR
THE MOST PART.
THERE IS LITTLE CHANGE IN THINKING FOR THE SEVERE FOR THURSDAY'S
EVENT, EXCEPT TO PUSH BACK THE IMPACT START TIME FROM 1 PM TO 3
PM IN THE NORTHWEST. FOR THE CENTRAL AREAS, WE WILL DELAY THE
START TIME FROM 4 PM TO 6 PM. WE WILL LEAVE THE THREAT AREA THE
SAME AS OUR INSTABILITY AREAS ARE STILL ON TRACK. STILL EXPECTING
THE SYSTEM TO LOSE INTENSITY AS WE TREK INTO THE LATE NIGHT HOURS
AS THE FRONT MOVES INTO THE SOUTHEAST HALF OF THE AREA. WITH ALL
OF OUR HYDROLOGIC RIVER POINTS FINALLY NOT IN FLOOD OR AT ACTION
STAGE, WE ARE IN BETTER SHAPE TO HANDLE THE UPCOMING EXPECTED
RAINFALL. THE EXPECTED FORECASTED STORM TOTAL RAINFALL FROM NOW
THROUGH FRIDAY NIGHT INDICATES THE LARGEST SWATH ALONG THE I-59
CORRIDOR OF AROUND 1 TO 1.5 INCHES. SO, NO FLOOD WATCHES ARE
PLANNED AT THIS TIME.
08
.LONG TERM...
THURSDAY AND THURSDAY NIGHT:
A CONDITIONAL RISK OF ISOLATED TO WIDELY SCATTERED SEVERE STORMS,
INCLUDING THE POTENTIAL FOR ISOLATED TORNADOES REMAINS IN THE
FORECAST FOR THURSDAY. THE EXTRATROPICAL CYCLONE THAT WILL UNDERGO
RAPID DEEPENING OVER THE PLAINS TODAY WILL BE GRADUALLY FILLING
ON THURSDAY AS IT LIFTS NORTHEASTWARD THROUGH THE UPPER MIDWEST,
AS IT WILL BE OCCLUDED AND VERTICALLY STACKED BY THIS TIME. A
POSITIVELY TILTED MID/UPPER LEVEL TROUGH AXIS WILL EXTEND
SOUTHWESTWARD FROM THE CYCLONE TO THE FOUR CORNERS REGION. MID AND
UPPER LEVEL SOUTHWESTERLY JETS WILL BE LOCATED ON THE SOUTHEAST
FLANK OF THE TROUGH/CYCLONE EXTENDING FROM TEXAS TO MICHIGAN. A
PACIFIC COLD FRONT WILL BE CROSSING MISSISSIPPI, PRECEDED BY A
40-50KT LLJ. THE QLCS CURRENTLY MARCHING ACROSS TEXAS WILL WEAKEN
AND THEN DISSIPATE ACROSS MISSISSIPPI/FAR NORTHWEST ALABAMA BY
EARLY THURSDAY MORNING AS IT OUT-RUNS THE INSTABILITY AND UPPER-
LEVEL SUPPORT LIFTS NORTH OF THE AREA. WHILE HIGH-RES MODELS
SEEMINGLY WASH OUT ANY APPARENT OUTFLOW BOUNDARY FROM THE FEATURE,
WILL NEED TO WATCH AND SEE IF IT DOES IN FACT LEAVE A BOUNDARY
AND/OR MOISTURE AXIS SOMEWHERE AS THIS COULD TRIGGER STORMS
THURSDAY AFTERNOON, OR ALTERNATIVELY TRIGGER SHOWERS THAT PREVENT
LATER DESTABILIZATION.
MID TO UPPER 60S DEW POINTS WILL POOL ALONG THE FRONT, AND WITH
STRONG SOUTHERLY FLOW TEMPERATURES SHOULD WARM WELL INTO THE 70S.
THIS WILL RESULT IN THE POTENTIAL FOR CAPE VALUES OF 1000-1500
J/KG WITH MID-LEVEL LAPSE RATES AROUND 6.5 C/KM. 50-60 KTS OF 0-6
KM WEST-SOUTHWESTERLY BULK SHEAR WILL BE PRESENT. WHILE THE
SURFACE CYCLONE WILL BE WEAKENING, ITS PRESSURE WILL STILL BE LOW
ENOUGH FOR PRESSURES TO FALL ACROSS THE NW HALF OF ALABAMA IN THE
SURFACE TROUGH, KEEPING WINDS RELATIVELY BACKED, WITH SRH VALUES
OF 200-300 M2/S2. SO WE HAVE INSTABILITY, MOISTURE, AND SHEAR, AND
FAVORABLE VALUES OF VARIOUS COMPOSITE PARAMETERS BASED ON THOSE
VARIABLES. THE BIG QUESTION MARK WILL BE A SOURCE OF LIFT. 500MB
HEIGHT TENDENCIES WILL BE FAIRLY NEUTRAL, WITH LITTLE IN THE WAY
OF UPPER-LEVEL JET DYNAMICS. CONVERGENCE ALONG THE PACIFIC FRONT
IS RELATIVELY WEAK DURING THE AFTERNOON HOURS, WITH WINDS SHIFTING
FROM SW TO WSW ALONG THE FRONT. THERE WILL BE SOME BROAD WARM AIR
ADVECTION PRESENT, POTENTIALLY A WEAK IMPULSE IN THE SUBTROPICAL
JET, AND DAYTIME HEATING.
THE WEAK FORCING AND SHEAR VECTOR ORIENTATION RELATIVE TO THE
FRONT SUGGEST A LACK OF UPSCALE GROWTH DURING THE AFTERNOON, WITH
INITIALLY SEMI-DISCRETE CELLS POTENTIALLY EVOLVING INTO BROKEN
LINES. CAMS GENERALLY AGREE WITH THIS, WITH SOME SMALL SUPERCELL
STRUCTURES AND WEAK UPDRAFT HELICITY PRESENT. NON CONVECTION-
ALLOWING MODELS GENERALLY INDICATE A BIT MORE QPF, THOUGH IT'S
UNCLEAR IF THIS WOULD BE CONVECTION OR JUST SHOWERS THAT HAVE A
STABILIZATION EFFECT (SUCH AS WHAT HAPPENED LAST SATURDAY). ALL IN
ALL, THE ENVIRONMENT IS THERE FOR SEVERE STORMS WITH ISOLATED
TORNADOES, BUT IT WILL COME DOWN TO WHAT HAPPENS ON THE STORM
SCALE, IF UPDRAFTS ARE ABLE TO SUSTAIN THEMSELVES WITHOUT BEING
SHEARED APART AND CAN OVERCOME SOME MID-LEVEL DRY AIR. SO THE
SEVERE THREAT REMAINS CONDITIONAL AND COVERAGE OF SEVERE STORMS
SEEMS TO BE LIMITED. THE MAIN THREAT SEEMS TO BE ISOLATED
TORNADOES AS THE CONVECTIVE MODE DOES NOT APPEAR TO FAVOR DAMAGING
WIND. THERE IS A FEW HUNDRED J/KG IN THE HAIL GROWTH ZONE, WHICH
SHOULD BE ENOUGH FOR SUB-SEVERE HAIL, BUT POTENTIAL FOR SEVERE
HAIL IS TOO LOW TO MENTION AT THIS TIME. MADE MINIMAL CHANGES TO
THE RISK AREAS, WITH THE SLIGHT RISK GENERALLY FOR THE
NORTHWESTERN THIRD OF THE AREA IN CLOSER PROXIMITY TO THE FRONT
AND BEST INSTABILITY. THE WRF-ARW WOULD SUGGEST A SMALL EASTWARD
EXTENSION OF THE SLIGHT RISK ACROSS OUR NORTHERN COUNTIES, BUT
REMAINS AN OUTLIER AT THIS TIME.
AS WE MOVE INTO THE EVENING HOURS, WINDS BEHIND THE FRONT BECOME
NORTHWESTERLY, INCREASING CONVERGENCE, AND WEAK HEIGHT FALLS BEGIN
AS THE TROUGH SLOWLY SINKS SOUTHEASTWARD. THIS WILL PROBABLY ALLOW
A MORE SOLID CONVECTIVE LINE TO FORM ALONG THE FRONT, BUT OF
RELATIVELY WEAK INTENSITY GIVEN THE ORIENTATION PARALLEL TO THE
LOW-LEVEL FLOW/0-3KM SHEAR VECTOR. WILL KEEP THE SEVERE THREAT
DURING THIS EVENING TRANSITION PERIOD, ENDING IT AFTER MIDNIGHT
WHEN LOW-LEVEL FLOW WEAKENS/VEERS. OUR FORECAST WILL REFLECT A
NON-NAM CONSENSUS ON TIMING. OVERALL RAINFALL AMOUNTS SHOULD
MAINLY BE AN INCH OR LESS, LIMITING FLOODING CONCERNS BEYOND MINOR
FLOODING OF POOR DRAINAGE AREAS. GRADIENT WINDS WILL ALSO BE
BREEZY AHEAD OF THE FRONT, BUT FORECAST GUSTS AT THIS TIME REMAIN
BELOW WIND ADVISORY CRITERIA.
NATIONAL WEATHER SERVICE BIRMINGHAM AL
425 PM CDT WED MAR 13 2019
.SHORT TERM...
THROUGH TONIGHT.
AND SEVERE CHANGES...
WE WILL BEGIN TO SEE SMALL RAIN CHANCES RETURN AS EARLY AS THIS
EVENING IN THE FAR WEST. BETTER RAIN CHANCES WILL BEGIN TO SLOWLY
NUDGE INTO THE WEST/NORTHWEST AFTER MIDNIGHT. AS FOR TEMPERATURES,
WE WILL BE VERY MILD TONIGHT AS WARM ADVECTION FROM THE GULF OF
MEXICO STREAMS INTO THE STATE. OUR LOWS TONIGHT WILL BE WELL ABOVE
NORMAL AND HIGHER THAN OUR EXPECTED HIGHS FOR MOST OF FRIDAY. WINDS
WILL REMAIN UP WITH TIGHT SURFACE PRESSURE GRADIENTS BETWEEN OUR
TWO AIRMASSES. WE SHOULD REMAIN BELOW WIND ADVISORY CRITERIA FOR
THE MOST PART.
THERE IS LITTLE CHANGE IN THINKING FOR THE SEVERE FOR THURSDAY'S
EVENT, EXCEPT TO PUSH BACK THE IMPACT START TIME FROM 1 PM TO 3
PM IN THE NORTHWEST. FOR THE CENTRAL AREAS, WE WILL DELAY THE
START TIME FROM 4 PM TO 6 PM. WE WILL LEAVE THE THREAT AREA THE
SAME AS OUR INSTABILITY AREAS ARE STILL ON TRACK. STILL EXPECTING
THE SYSTEM TO LOSE INTENSITY AS WE TREK INTO THE LATE NIGHT HOURS
AS THE FRONT MOVES INTO THE SOUTHEAST HALF OF THE AREA. WITH ALL
OF OUR HYDROLOGIC RIVER POINTS FINALLY NOT IN FLOOD OR AT ACTION
STAGE, WE ARE IN BETTER SHAPE TO HANDLE THE UPCOMING EXPECTED
RAINFALL. THE EXPECTED FORECASTED STORM TOTAL RAINFALL FROM NOW
THROUGH FRIDAY NIGHT INDICATES THE LARGEST SWATH ALONG THE I-59
CORRIDOR OF AROUND 1 TO 1.5 INCHES. SO, NO FLOOD WATCHES ARE
PLANNED AT THIS TIME.
08
.LONG TERM...
THURSDAY AND THURSDAY NIGHT:
A CONDITIONAL RISK OF ISOLATED TO WIDELY SCATTERED SEVERE STORMS,
INCLUDING THE POTENTIAL FOR ISOLATED TORNADOES REMAINS IN THE
FORECAST FOR THURSDAY. THE EXTRATROPICAL CYCLONE THAT WILL UNDERGO
RAPID DEEPENING OVER THE PLAINS TODAY WILL BE GRADUALLY FILLING
ON THURSDAY AS IT LIFTS NORTHEASTWARD THROUGH THE UPPER MIDWEST,
AS IT WILL BE OCCLUDED AND VERTICALLY STACKED BY THIS TIME. A
POSITIVELY TILTED MID/UPPER LEVEL TROUGH AXIS WILL EXTEND
SOUTHWESTWARD FROM THE CYCLONE TO THE FOUR CORNERS REGION. MID AND
UPPER LEVEL SOUTHWESTERLY JETS WILL BE LOCATED ON THE SOUTHEAST
FLANK OF THE TROUGH/CYCLONE EXTENDING FROM TEXAS TO MICHIGAN. A
PACIFIC COLD FRONT WILL BE CROSSING MISSISSIPPI, PRECEDED BY A
40-50KT LLJ. THE QLCS CURRENTLY MARCHING ACROSS TEXAS WILL WEAKEN
AND THEN DISSIPATE ACROSS MISSISSIPPI/FAR NORTHWEST ALABAMA BY
EARLY THURSDAY MORNING AS IT OUT-RUNS THE INSTABILITY AND UPPER-
LEVEL SUPPORT LIFTS NORTH OF THE AREA. WHILE HIGH-RES MODELS
SEEMINGLY WASH OUT ANY APPARENT OUTFLOW BOUNDARY FROM THE FEATURE,
WILL NEED TO WATCH AND SEE IF IT DOES IN FACT LEAVE A BOUNDARY
AND/OR MOISTURE AXIS SOMEWHERE AS THIS COULD TRIGGER STORMS
THURSDAY AFTERNOON, OR ALTERNATIVELY TRIGGER SHOWERS THAT PREVENT
LATER DESTABILIZATION.
MID TO UPPER 60S DEW POINTS WILL POOL ALONG THE FRONT, AND WITH
STRONG SOUTHERLY FLOW TEMPERATURES SHOULD WARM WELL INTO THE 70S.
THIS WILL RESULT IN THE POTENTIAL FOR CAPE VALUES OF 1000-1500
J/KG WITH MID-LEVEL LAPSE RATES AROUND 6.5 C/KM. 50-60 KTS OF 0-6
KM WEST-SOUTHWESTERLY BULK SHEAR WILL BE PRESENT. WHILE THE
SURFACE CYCLONE WILL BE WEAKENING, ITS PRESSURE WILL STILL BE LOW
ENOUGH FOR PRESSURES TO FALL ACROSS THE NW HALF OF ALABAMA IN THE
SURFACE TROUGH, KEEPING WINDS RELATIVELY BACKED, WITH SRH VALUES
OF 200-300 M2/S2. SO WE HAVE INSTABILITY, MOISTURE, AND SHEAR, AND
FAVORABLE VALUES OF VARIOUS COMPOSITE PARAMETERS BASED ON THOSE
VARIABLES. THE BIG QUESTION MARK WILL BE A SOURCE OF LIFT. 500MB
HEIGHT TENDENCIES WILL BE FAIRLY NEUTRAL, WITH LITTLE IN THE WAY
OF UPPER-LEVEL JET DYNAMICS. CONVERGENCE ALONG THE PACIFIC FRONT
IS RELATIVELY WEAK DURING THE AFTERNOON HOURS, WITH WINDS SHIFTING
FROM SW TO WSW ALONG THE FRONT. THERE WILL BE SOME BROAD WARM AIR
ADVECTION PRESENT, POTENTIALLY A WEAK IMPULSE IN THE SUBTROPICAL
JET, AND DAYTIME HEATING.
THE WEAK FORCING AND SHEAR VECTOR ORIENTATION RELATIVE TO THE
FRONT SUGGEST A LACK OF UPSCALE GROWTH DURING THE AFTERNOON, WITH
INITIALLY SEMI-DISCRETE CELLS POTENTIALLY EVOLVING INTO BROKEN
LINES. CAMS GENERALLY AGREE WITH THIS, WITH SOME SMALL SUPERCELL
STRUCTURES AND WEAK UPDRAFT HELICITY PRESENT. NON CONVECTION-
ALLOWING MODELS GENERALLY INDICATE A BIT MORE QPF, THOUGH IT'S
UNCLEAR IF THIS WOULD BE CONVECTION OR JUST SHOWERS THAT HAVE A
STABILIZATION EFFECT (SUCH AS WHAT HAPPENED LAST SATURDAY). ALL IN
ALL, THE ENVIRONMENT IS THERE FOR SEVERE STORMS WITH ISOLATED
TORNADOES, BUT IT WILL COME DOWN TO WHAT HAPPENS ON THE STORM
SCALE, IF UPDRAFTS ARE ABLE TO SUSTAIN THEMSELVES WITHOUT BEING
SHEARED APART AND CAN OVERCOME SOME MID-LEVEL DRY AIR. SO THE
SEVERE THREAT REMAINS CONDITIONAL AND COVERAGE OF SEVERE STORMS
SEEMS TO BE LIMITED. THE MAIN THREAT SEEMS TO BE ISOLATED
TORNADOES AS THE CONVECTIVE MODE DOES NOT APPEAR TO FAVOR DAMAGING
WIND. THERE IS A FEW HUNDRED J/KG IN THE HAIL GROWTH ZONE, WHICH
SHOULD BE ENOUGH FOR SUB-SEVERE HAIL, BUT POTENTIAL FOR SEVERE
HAIL IS TOO LOW TO MENTION AT THIS TIME. MADE MINIMAL CHANGES TO
THE RISK AREAS, WITH THE SLIGHT RISK GENERALLY FOR THE
NORTHWESTERN THIRD OF THE AREA IN CLOSER PROXIMITY TO THE FRONT
AND BEST INSTABILITY. THE WRF-ARW WOULD SUGGEST A SMALL EASTWARD
EXTENSION OF THE SLIGHT RISK ACROSS OUR NORTHERN COUNTIES, BUT
REMAINS AN OUTLIER AT THIS TIME.
AS WE MOVE INTO THE EVENING HOURS, WINDS BEHIND THE FRONT BECOME
NORTHWESTERLY, INCREASING CONVERGENCE, AND WEAK HEIGHT FALLS BEGIN
AS THE TROUGH SLOWLY SINKS SOUTHEASTWARD. THIS WILL PROBABLY ALLOW
A MORE SOLID CONVECTIVE LINE TO FORM ALONG THE FRONT, BUT OF
RELATIVELY WEAK INTENSITY GIVEN THE ORIENTATION PARALLEL TO THE
LOW-LEVEL FLOW/0-3KM SHEAR VECTOR. WILL KEEP THE SEVERE THREAT
DURING THIS EVENING TRANSITION PERIOD, ENDING IT AFTER MIDNIGHT
WHEN LOW-LEVEL FLOW WEAKENS/VEERS. OUR FORECAST WILL REFLECT A
NON-NAM CONSENSUS ON TIMING. OVERALL RAINFALL AMOUNTS SHOULD
MAINLY BE AN INCH OR LESS, LIMITING FLOODING CONCERNS BEYOND MINOR
FLOODING OF POOR DRAINAGE AREAS. GRADIENT WINDS WILL ALSO BE
BREEZY AHEAD OF THE FRONT, BUT FORECAST GUSTS AT THIS TIME REMAIN
BELOW WIND ADVISORY CRITERIA.
Still looking at mainly a high wind threat and low tornado threat.
LOOKS LIKE SOME PRETTY GOOD DISCREET CELLS
Z
Zander98al
Guest
Guys check out that 00z hrrr ?
WIATING ON IT TO FUN A LITTLE FURTHER NOW
Z
Zander98al
Guest
Z
Zander98al
Guest
Supercells popping up around the 2-4 time frame it looks to stay discrete at the begging. Instability is pretty good for these storms too feed on, especially prime heating of the day.
Last edited by a moderator:
YEA THOSE CELLS WILL HAVE PLENTY TO FEED ON TEMPS IN THE 70'S DEW POINTS IN THE HIGH 60'S /LOW 70'S SBCAPE ANYWHERE FROM 1300/2100J/KG
GeorgiaGirl
Member
I just briefly checked the HRRR, yeah it's more nasty than I thought it'd be in Alabama.
Good news however is the long range HRRR isn't exactly reliable. But stay aware for sure.
Good news however is the long range HRRR isn't exactly reliable. But stay aware for sure.
Z
Zander98al
Guest
hopefully thatll be correct, just checked the sounding for birmingham at 4 oclock and it indicated a pds watch. Doubt thatll happen but something that needs to be watched for sure wouldnt be suprised for a tornado watch around 2 oclock
Not bad, it does dry out quick tho as you go up further (above 850 hPa), which tornadoes don’t like, also you want BRN shear over 200 m2/s2, lapses aren’t the best as well, this pds is a bit deceiving 
Even with what I mentioned, I never like discrete activity, hopefully the LR hrrr just being the LR hrrr, lol
Z
Zander98al
Guest
Lets hope, will know more by tommrow morning, and what environment storms will be working in.
NWMSGuy
Member
Any thoughts on the severe warned storm in northwest Ms? Looks like some rotation to me.