[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 050919
SWOMCD
SPC MCD 050918
GAZ000-TNZ000-ALZ000-MSZ000-051145-

MESOSCALE DISCUSSION 1439
NWS STORM PREDICTION CENTER NORMAN OK
0418 AM CDT SUN JUL 05 2009

AREAS AFFECTED...PORTIONS NRN AL...SRN MIDDLE TN...NERN MS...EXTREME
NWRN GA.

CONCERNING...HEAVY RAINFALL

VALID 050918Z - 051145Z

MCS AND RELATED HEAVY RAIN SUPPORTING CONDITIONS DISCUSSED IN
EARLIER MESOSCALE DISCUSSION 1438 SHOULD SHIFT SWD ACROSS MORE OF
NRN AL THROUGH 12Z.  SOME SEWD TRANSLATION AND WWD
MERGING/BACKBUILDING PROCESSES COULD EXPAND MCS INTO ADJACENT
PORTIONS GA/MS RESPECTIVELY.  AVERAGE RAIN RATES SHOULD BE LOWER
THAN THEY WERE IN TN -- EXPECT 1-2 INCHES/HOUR WITH ISOLATED/BRIEFLY
HIGHER RATES -- BUT STILL SUFFICIENT FOR RELATIVELY CONCENTRATED
HEAVY RAIN THREAT GIVEN EXPECTED MERGING/TRAINING OF CELLS.

ELEVATED INFLOW REGION WILL REMAIN CHARACTERIZED BY FAVORABLE LOW
LEVEL WAA AND PW NEAR 2 INCHES...BASED ON GPS DATA AND MODEL
SOUNDINGS.  LLJ SHOULD VEER SLIGHTLY THROUGH REMAINDER PRE-DAWN
HOURS...AS PART OF DEEP LAYER STG MOISTURE TRANSPORT WITHIN NARROW
E-W CORRIDOR EXTENDING FROM NRN GA BACK WWD ACROSS ARKLATEX REGION.
GIVEN WEAK DEEP-LAYER LAPSE RATES...BUOYANCY WILL REMAIN MRGL BUT
STILL SUPPORTIVE...WITH MUCAPE IN 300-700 J/KG RANGE.  OVER SRN MID
TN...STG LOW LEVEL WAA/ISENTROPIC LIFT ATOP MCS OUTFLOW POOL MAY
CONTINUE TO GENERATE HEAVY RAIN-PRODUCING CONVECTION TO AGGRAVATE
HAZARD FROM EARLIER ACTIVITY.  ISOLATED STG TO DAMAGING GUSTS STILL
MAY OCCUR MAINLY OVER SRN PERIPHERY OF MCS WHERE NEAR-SURFACE
STABILITY IS RELATIVELY MINIMIZED.

MAGNITUDE OF BOTH LLJ AND RELATED MOISTURE TRANSPORT SHOULD WEAKEN
AFTER ABOUT 11Z...WHILE LOW LEVEL FLOW ABOVE SFC ALSO BECOMES
ALIGNED MORE PARALLEL TO CONVECTIVE PLUME.  THIS SHOULD SUPPORT NET
WEAKENING TREND FOR REMAINDER MORNING UNTIL LATER DIURNAL HEATING
STGLY DESTABILIZES AIR MASS S OF RESULTING BOUNDARY...AS DISCUSSED
IN DAY-1 SVR OUTLOOK.

..EDWARDS.. 07/05/2009

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MRX...FFC...OHX...BMX...HUN...MEG...

LAT...LON   34118699 34138863 34558842 35138778 35558761 35458631
            34638552 34288512 33828609 34118699



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