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Winter 2015-16

Mr Bob

By Mr Bob,
in Tennessee Valley

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JayCee

JayCee

Posted
Posted

I find these mountain wave events very interesting, especially considering how localized they can be.  I've observed howling winds close or in the foothills, while 10 miles away at my house northeast of Sevierville, there is just a light breeze blowing.  Fascinating--how different the weather can be within such a short distance. 


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Stovepipe

Stovepipe

Posted
Posted

12z Euro parallel FTW, ya'll. Time running out so I feel it is perfectly acceptable to go to d10 since we may have nothing else to track. Nice blocking and storm signals for that time frame. If nothing else, it keeps things interesting...

 

Nice 10+ inches on the eastern third of TN there.  The lack of fantasy has been boring, good find!

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Runman292

Runman292

Posted
Posted

Here's the AFD from MRX. They appear to be concerned about the Severe threat Wednesday morning.

FOR TUESDAY...GENERALLY A BREAK IN THE ACTION ANTICIPATED AS THE

GULF COASTS CYCLONE INTENSIFIES. A STRONG NEGATIVELY TILTED WAVE

WILL MOVE QUICKLY NORTHEAST ACROSS THE TENNESSEE VALLEY TUESDAY

NIGHT AND OHIO VALLEY FOR WEDNESDAY. STRONG JET DYNAMICS WILL MOVE

THROUGH THE AREA TUESDAY NIGHT AND WEDNESDAY WITH FRONTO BOUNDARY

MOVING ACROSS CHA BETWEEN 12-15Z...TYS NEAR 18Z...AND TRI AROUND

21Z WEDNESDAY.

FORECAST SOUNDINGS SHOW MAGINAL INSTABILITY WITH CAPES OF 500-1000

J/KG ALONG WITH STRONG LOW-LEVEL JET OF 60-65KTS AT 850MB...AND

GOOD SHEAR. WE ARE CONCERNED THAT A LINE OF SHOWERS AND

THUNDERSTORMS WILL QUICKLY MOVE NORTHEAST UP THE VALLEY BEGINNING

WEDNESDAY MORNING WITH DAMAGING WINDS BEING THE MAIN CONCERN.

HOWEVER...ENOUGH LOW-LEVEL INSTABILITY AND POTENTIAL WARM FRONTAL

BOUNDARY ACROSS THE CHA AREA FOR A LOW CHANCE OF TORNADOES. HAVE

INCLUDED IN THE HWO.

BESIDES THE SHOWERS AND STORMS...THE TIGHTENING PRESSURE GRADIENT

AND THE STRENGTHENING CYCLO-GENESIS WILL PRODUCE A STRONG LOW-LEVEL

JET FOR TUESDAY NIGHT AND WEDNESDAY. CONDITIONS ARE FAVORABLE FOR

MOUNTAIN WAVE DEVELOP AS WELL...SO HAVE ISSUED A HIGH WIND WATCH

FOR THE EAST TENNESSEE MOUNTAINS AND ADJACENT FOOTHILLS.

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Stormcatt

Stormcatt

Posted
Posted

12z Euro parallel FTW, ya'll. Time running out so I feel it is perfectly acceptable to go to d10 since we may have nothing else to track. Nice blocking and storm signals for that time frame. If nothing else, it keeps things interesting...

12z euro op was very close to the para solution just needs to shift the ridge a little west and sharpen it up. 18z GFS was also very close to a para solution . The 3rd-5th period is very interesting

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jaxjagman

jaxjagman

Posted
Posted

Here's the AFD from MRX. They appear to be concerned about the Severe threat Wednesday morning.

FOR TUESDAY...GENERALLY A BREAK IN THE ACTION ANTICIPATED AS THE

GULF COASTS CYCLONE INTENSIFIES. A STRONG NEGATIVELY TILTED WAVE

WILL MOVE QUICKLY NORTHEAST ACROSS THE TENNESSEE VALLEY TUESDAY

NIGHT AND OHIO VALLEY FOR WEDNESDAY. STRONG JET DYNAMICS WILL MOVE

THROUGH THE AREA TUESDAY NIGHT AND WEDNESDAY WITH FRONTO BOUNDARY

MOVING ACROSS CHA BETWEEN 12-15Z...TYS NEAR 18Z...AND TRI AROUND

21Z WEDNESDAY.

FORECAST SOUNDINGS SHOW MAGINAL INSTABILITY WITH CAPES OF 500-1000

J/KG ALONG WITH STRONG LOW-LEVEL JET OF 60-65KTS AT 850MB...AND

GOOD SHEAR. WE ARE CONCERNED THAT A LINE OF SHOWERS AND

THUNDERSTORMS WILL QUICKLY MOVE NORTHEAST UP THE VALLEY BEGINNING

WEDNESDAY MORNING WITH DAMAGING WINDS BEING THE MAIN CONCERN.

HOWEVER...ENOUGH LOW-LEVEL INSTABILITY AND POTENTIAL WARM FRONTAL

BOUNDARY ACROSS THE CHA AREA FOR A LOW CHANCE OF TORNADOES. HAVE

INCLUDED IN THE HWO.

BESIDES THE SHOWERS AND STORMS...THE TIGHTENING PRESSURE GRADIENT

AND THE STRENGTHENING CYCLO-GENESIS WILL PRODUCE A STRONG LOW-LEVEL

JET FOR TUESDAY NIGHT AND WEDNESDAY. CONDITIONS ARE FAVORABLE FOR

MOUNTAIN WAVE DEVELOP AS WELL...SO HAVE ISSUED A HIGH WIND WATCH

FOR THE EAST TENNESSEE MOUNTAINS AND ADJACENT FOOTHILLS.

Instabilities were better this afternoon.Last run of the NAM and GFS  showed some better cape,espeicaly the NAM

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John1122

John1122

Posted
Posted

Regardless of what the GFS is currently showing in the LR, if the AO tanks down towards -3 the first week of March, and the PNA is positive as it's forecast to be, cold air will come south. MJO has bigger effects the later on in the year, as has been discussed here, it's supposed to enter 8 in a day or two. There is often a 10-12 day lag in it's effects reaching the United States. 

 

So right now, if all those indicies forecast come to pass, it should be a cold period from probably March 2nd - 10th at least.

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Runman292

Runman292

Posted
Posted

Looks like MRX is backing off the Severe threat somewhat. They still think the Southern Valley (Southwest of Knoxville) could see scattered damaging wind gusts up to 60mph and flash flooding possible in the stronger storms, while an isolated Tornado can't be ruled out with the wind shear. Everywhere else, a few thunderstorms with gusty winds and localized flooding possible.

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JayCee

JayCee

Posted
Posted

VERY detailed discussion from MRX this afternoon:

 

 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
334 PM EST TUE FEB 23 2016

.SHORT TERM...TONIGHT AND TOMORROW)...POTENT LOW PRESSURE SYSTEM WILL
TRACK TOWARD OUR AREA TONIGHT AND TOMORROW...WHICH WILL TRANSLATE
TO INCREASING COVERAGE IN SHOWERS THIS EVENING FROM SOUTHWEST TO
NORTHEAST AS THE SYSTEM APPROACHES. THERE ARE A FEW DIFFERENT
THREATS WITH THIS SYSTEM AND WILL BREAK THEM UP ACCORDINGLY.

SEVERE THREAT...STRONG 300 MB JET WILL ROUND THE BASE OF THE TROUGH
AND PUT OUR AREA UNDER THE RIGHT EXIT REGION OF THE JET BY LATE
TONIGHT AND THROUGH EARLY TOMORROW MORNING. CLOSED LOW AT 500 MB
SHOWS STRONG VORTICITY MOVING INTO OUR AREA AFTER MIDNIGHT. MAIN
LINE OF CONVECTION WILL CLOSELY ALIGN WITH THIS AREA OF VORTICITY
MOVING IN. A VERY STRONG 850 MB JET WILL ALSO MOVE IN OVERNIGHT. THE
NAM SHOWS A 60 TO 70 KTS WHILE THE GFS IS A LITTLE LOWER AT 55 TO 65
KTS. HI RES SHORT RANGE MODELS SHOW BROKEN LINE OF CONVECTION MOVING
INTO THE SOUTHERN PLATEAU AROUND 06Z. BY 09Z THE LINE SHOULD BE
ACROSS MOST OF THE SOUTHERN VALLEY...BY 12Z INTO THE CENTRAL AND
NORTHERN VALLEY AND BY 15Z UP INTO NETN AND SWVA. SOUNDINGS SHOW AN
INVERSION IN PLACE WHILE THE MAIN LINE OF CONVECTION MOVES THROUGH.
THIS WILL LIKELY INHIBIT SOME OF THE STRONGER WINDS FROM MIXING DOWN
TO THE SURFACE BUT ANY STRONGER CORE COULD POTENTIAL TAP INTO THE 60
TO 70 KT 850 JET AND BRING HIGHER WINDS DOWN TO THE SURFACE. THE
INVERSION SHOULD KEEP THE RISK OF AN ISOLATED TORNADO EXTREMELY
LOW BUT DUE TO THE HIGH SHEAR VALUES IN THE LOWEST LEVELS STILL
CAN`T 100% RULE OUT AN ISOLATED SPIN UP ACROSS OUR SOUTHERN MOST
AREAS. AGAIN...THE SOUTHERN PLATEAU AND SOUTHERN VALLEY HAVE THE
GREATEST RISK OF SEEING A STRONG STORM...BUT EVEN THAT RISK IS
RELATIVELY LOW. THE MAIN THREATS WILL BE WIND DAMAGE AND HEAVY
RAINFALL. THE HEAVY RAINFALL THREAT IS DUE TO SOUNDINGS SHOWING PWS
AROUND THE 95TH PERCENTILE BY EARLY TOMORROW MORNING. WILL LEAVE
PREVIOUS FLASH FLOOD WATCH UNCHANGED AS GREATEST THREAT FOR HEAVY
RAIN STILL APPEARS CONFINED TO THOSE SAME AREAS. 1 TO 2 INCHES OF
RAIN STILL LOOK POSSIBLE ACROSS THE WATCH AREA FROM TONIGHT THROUGH
TOMORROW AFTERNOON.


WIND THREAT....DECIDED TO UPGRADE THE HIGH WIND WATCH TO A HIGH WIND
WARNING AS THE CONDITIONS LOOK FAVORABLE FOR BOTH HIGH WINDS AND
MOUNTAIN WAVES. ALSO ADDED A FEW COUNTIES THAT WEREN`T PREVIOUSLY IN
THE WATCH AREA. THE INVERSION AND SE WINDS COMING ACROSS THE
MOUNTAINS AT 850MB SHOULD PROVIDE IDEAL CONDITIONS FOR MOUNTAIN
WAVES ACROSS THE HIGHER TERRAIN AND FOOTHILLS. LOCATIONS SUCH AS
CAMP CREEK COULD SEE WIND GUSTS IN EXCESS OF 75 MPH. ALL OTHER
AREAS HAVE BEEN PLACED IN A WIND ADVISORY DUE TO THE STRENGTH OF
THE GRADIENT WINDS AND ORIENTATION OF THE WINDS THEMSELVES. SW
WINDS GIVE FAVOR TO HIGHER WINDS UP THROUGH THE VALLEY.


AFTER THE MAIN LINE OF CONVECTION MOVES THROUGH IN THE MORNING HOURS
WE WILL SEE A BRIEF BREAK DUE TO BEING IN THE DRY SLOT. WE MAY EVEN
SEE BRIEF CLEARING ACROSS THE CENTRAL VALLEY. REDEVELOPMENT IS
EXPECTED IN THE AFTERNOON HOURS AS THE CENTER OF THE LOW PASSES
JUST NW OF THE AREA. EXPECTING SHOWERS AT THIS TIME AND LEFT
MENTION OF THUNDER OUT OF FORECAST BUT SOUNDINGS DUE SHOW SOME
INSTABILITY DURING THE AFTERNOON HOURS BUT HOW MUCH MOISTURE IS
LEFT WILL BE THE BIGGEST QUESTION. THE NEXT FORECAST MAY HAVE TO
INCLUDE THUNDER FOR TOMORROW AFTERNOON FOR PORTIONS OF THE AREA.
TEMPS WILL FALL THROUGH THE DAY TOMORROW AS COLD AIR MOVES IN ON
THE BACK SIDE OF THE LOW. BREEZY WINDS CONTINUE THROUGH THE
AFTERNOON HOURS DUE TO A TIGHT PRESSURE GRADIENT.






.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)...MODELS IN DECENT
AGREEMENT EARLY ON...BUT DECREASE IN AGREEMENT AND RUN TO RUN
CONSISTENCY LATE IN THE PERIOD. FORECAST CONFIDENCE IS ABOUT AVERAGE
FOR THIS TIME OF YEAR EARLY IN THE PERIOD...BUT BELOW AVERAGE LATE.
COLDER AIR WILL BE PUSHING IN BEHIND THE DEPARTING LOW PRESSURE
SYSTEM WEDNESDAY NIGHT...AND WITH FREEZING LEVELS LOWERING WE WILL
SEE A TRANSITION FROM RAIN SHOWERS TO SNOW SHOWERS.  ENOUGH MOISTURE
SHOULD LINGER IN THE WEST/NORTHWEST FLOW THURSDAY THROUGH THURSDAY
NIGHT TO KEEP SOME SCATTERED TO NUMEROUS SNOW SHOWERS...POSSIBLY
RAIN SHOWERS VALLEYS...AROUND ESPECIALLY NORTH AND MOUNTAINS. SNOW
SHOWERS THURSDAY NIGHT WILL BE AIDED BY SOME SHORT WAVE ENERGY
DROPPING SOUTHEAST THROUGH THE TROUGH...AND FLOW TURNS MORE
NORTHWEST/MORE FAVORABLE FOR UPSLOPE SNOW SHOWERS THURSDAY NIGHT
WITH A SECOND SURGE OF COLD ADVECTION. WILL LIKELY SEE SIGNIFICANT
SNOW ACCUMULATIONS MAINLY ACROSS THE HIGHER ELEVATIONS...AND SOME
LIGHT ACCUMULATION CANNOT BE RULED OUT EVEN INTO VALLEY AREAS MAINLY
NORTH.

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John1122

John1122

Posted
Posted

A few days ago the models were just showing awesome blocking. The Euro had the polar vortex just north of the Lakes. That's pretty much gone now. We'll see if they bring that look back or something similar. Right now the whole patten is progressive and the cold shots look like they come in a day or two at a time behind cutters.

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Stormcatt

Stormcatt

Posted
Posted

A few days ago the models were just showing awesome blocking. The Euro had the polar vortex just north of the Lakes. That's pretty much gone now. We'll see if they bring that look back or something similar. Right now the whole patten is progressive and the cold shots look like they come in a day or two at a time behind cutters.

Story of the winter

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John1122

John1122

Posted
Posted

Man, the RGEM is healthy with the back side/NW flow snow, drops 2-4+ inches on the Plateau and Mountains and 1-3 in NE TN/SWVA/SEKY. NAM 4K is 1-3 over the Plateau/Mountains and not much elsewhere.  GFS looks like 1-3 over the same areas with 4+ over the favored spots. Both WRF models show similar amounts too.

 

I'd trim 50-60 percent off those totals below 2000-3000 feet.

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