[Email1] Area Forecast Discussion for long term outlook

[Ronnie King]

Hello everyone. Here is part of the AFD - Area Forecast Discussion - for
the County Warn Area of the Birmingham NWS Forecast Office.
This was just issued a few minutes ago and I felt it is something we should
all be aware of.

===========

.LONG TERM...

THE MAIN FOCUS OF THE FORECAST IS STILL ON THIS WEEKEND AS A PIECE
OF ENERGY SEPARATES FROM THE MAIN TROUGH AND TRACKS NORTHEAST TOWARD
THE MIDWEST AND GREAT LAKES REGION. THIS SHORTWAVE IS NOW MUCH MORE
DEFINED AND MORE PROMINENT THAN WHAT WAS SHOWN THE PAST COUPLE OF
DAYS. THIS STRONGER SHORTWAVE IS TRANSLATING TO A DEEPENING SFC
LOW...WHICH COULD SPELL MORE TROUBLE FOR OUR AREA. LET'S TAKE A LOOK
AT THE SETUP IN A BIT MORE DETAIL.

MODEL AGREEMENT HAS INCREASED SOMEWHAT BUT THERE ARE STILL SOME
DISCREPANCIES...INCLUDING TIMING...WHICH CREATES A BIT OF A PROBLEM.
DIFFERENCES ASIDE...HERE IS WHAT WE DO KNOW. AS THE OVERALL SYSTEM
BECOMES MORE MATURE AND THE SFC LOW ACQUIRES BOTH WARM/COLD SFC
FRONTAL FEATURES...A DRY LINE WILL ALSO DEVELOP AHEAD OF THE COLD
FRONT JUST WEST OF THE MS RIVER ON SATURDAY. THE SOUTHEAST STATES
WILL BE SITTING IN A VERY WARM...MOIST AND UNSTABLE AIRMASS. A
SQUALL LINE WILL ESTABLISH ITSELF ALONG THE DRYLINE AS IT CROSSES
THE RIVER. SOUNDINGS IN EAST MS SATURDAY AFTERNOON SHOW A VERY WEAK
CAPPING INVERSION...SO WE WILL HAVE TO BE ON THE LOOKOUT FOR
INDIVIDUAL CELL GROWTH AHEAD OF THE SQUALL LINE WHICH COULD MOVE
INTO OUR FAR W/NW COUNTIES LATE SATURDAY EVENING.

EVEN THOUGH THERE ARE STILL SOME TIMING ISSUES REGARDING THE SQUALL
LINE...THE GOOD NEWS IS THAT MODELS ARE TRYING TO COME TO A
CONSENSUS. RIGHT NOW...OUR THINKING IS THAT THE LINE OF STORMS WILL
MOST LIKELY ENTER OUR CWA SOMETIME AFTER MIDNIGHT SATURDAY NIGHT.
SEVERE PARAMETERS ACROSS CENTRAL ALABAMA ARE DEFINITELY NOT LACKING
AND ARE BECOMING QUITE IMPRESSIVE AS OF THE LATEST GUIDANCE. CAPE
VALUES OFF THE GFS ARE AROUND 500 J/KG...BUT IT APPEARS TO TRY TO
DECOUPLE THE BOUNDARY LAYER OVERNIGHT...WHICH DOESN'T SEEM LIKELY AT
THIS POINT. WITH THAT SAID...INSTABILITIES COULD BE A BIT HIGHER
THAN WHAT THE MODELS ARE DEPICTING. AFTER COMPARING PROFILES FROM
YESTERDAY TO THOSE OF TODAY FOR WEST AL WE CAN SEE THAT THERE IS
NOW A BIT OF DRY AIR SHOWING UP IN THE MID LEVELS...WHICH IS KEY IN
HELPING GET THAT EXTRA PUNCH FOR SVR WX. PERHAPS THE MOST IMPRESSIVE
FEATURE IS THE WIND FIELD AHEAD OF THE SYSTEM. WINDS AT 850MB ARE
UPWARDS OF 60-65 KTS WITH 925MB WINDS OF 50+ KTS SATURDAY NIGHT INTO
SUNDAY MORNING. SFC WINDS ALSO TRY TO BACK A LITTLE TO THE SE DUE TO
THE STRONGER SFC LOW CENTER. ALL OF THIS CREATES A MORE THAN
ADEQUATE AMOUNT OF SHEAR...0-6KM BULK SHEAR IS AROUND 60 KTS WITH
0-1KM SRH OF CLOSE TO 400 M2/S2. WITH ALL OF THAT SAID...WE WILL BE
LOOKING AT A THREAT OF DAMAGING WINDS AND ISOLATED TORNADOES
SATURDAY NIGHT INTO SUNDAY.

THE SEVERE THREAT LOOKS TO DIMINISH AS WE MOVE FURTHER INTO SUNDAY
AS THE MAIN DYNAMICS PULL OUT TO THE NORTHEAST. WE COULD SEE SOME
REDEVELOPMENT ALONG THE LINE ACROSS THE SOUTHEAST COUNTIES SUNDAY
AFTERNOON BUT EVERYTHING SHOULD REMAIN BELOW SVR LIMITS. THE COLD
FRONT WILL EVENTUALLY CATCH UP TO WHAT'S LEFT OF THE INITIAL LINE OF
STORMS SUNDAY NIGHT WITH A FEW SHOWERS LINGERING IN THE SOUTHEAST
THRU MONDAY MORNING.

====

OK Folks there you are.  Keep these facts in mind as you plan for
your weekend activities.

Thanks



-- 
Ronnie King
WX4RON
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