Ridge Breaking Down, Possible MS Surface Low

[GeneratorPower]

The seemingly permanent high pressure ridge over the SE US is finally breaking down/moving off. First day under 100F here in a long time, and we're getting rain daily. Also mentioning a GOM surface low hitting MS Gulf Coast from the current BOC blob.

May get some action out of this pattern.

000
FXUS64 KHUN 260820
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
320 AM CDT SUN AUG 26 2007

.DISCUSSION...
EARLY MRNG SFC ANALYSIS SHOWING A WEAK SFC TROUGH/LLVL BOUNDARY
SLOWLY SHIFTING SEWRD INTO NORTHWEST AL. THIS FEATURE...ALONG WITH
NUMEROUS RESIDUAL OUTFLOW BOUNDARIES...CONTINUE TO HELP FOCUS
SCT`D AREAS OF -SHRA ACROSS NORTHERN/WESTERN SECTIONS OF THE HUN
CWA. WATER VAPOR IMAGERY AND UPPER AIR CHARTS SHOW THE SOUTHERN
EXTENSION OF AN UPPER TROUGH AXIS ALSO MOVING THROUGH...WITH A
NARROW POCKET OF DRIER AIR DROPPING SEWRD BEHIND THIS TROUGH
ACROSS PARTS OF AR/MO. AREA TEMPERATURES AS 08Z REMAIN IN THE
LOW/MID 70S...WITH DEWPTS AROUND 70F.

THE AFOREMENTIONED FRONTAL BOUNDARY WILL CONTINUE TO SLIDE ACROSS
THE CENTRAL TN VALLEY THROUGH THE DAY. THE ADDED LLVL CONVERGENCE...
COMBINED WITH SUFFICIENT MOISTURE...WILL MAINTAIN AT LEAST A LOW
PCPN CHANCE ACROSS WESTERN/CENTRAL AREAS DURING THE MORNING
HOURS...WITH A POTENTIAL UPSWING IN DEVELOPMENT COINCIDING WITH
PEAK HEATING ACROSS EASTERN AREAS BY THIS AFTN/EARLY EVNG.
THUS...WILL TAPER POPS FROM LOW CHANCE EAST...TO ONLY 10% ACROSS
NORTHWEST AL. LATEST SOUNDING DATA ACROSS EASTERN AREAS SHOW
DEEPER MOISTURE EXTENDING THROUGH THE MID-LEVELS...WHICH MAY
HINDER MICROBURST POTENTIAL TODAY. HOWEVER...NAM BUFR SOUNDINGS
INDICATE CAPE VALUES APPROACHING 3 KJ/KG AT ALBERTVILLE...SO WITH
STEEPENING LAPSE RATES CANNOT RULE A FEW STORMS CONTAINING
STRONGER WIND GUSTS DURING PEAK HEATING. IN ADDITION...DRIER AIR
ABOVE 600 MB WILL BE ADVECTING INTO WESTERN SECTIONS BY THIS
AFTN...WHICH COULD ALSO HELP ENHANCE DOWNDRAFT POTENTIAL. AS FOR
TEMPERATURES...GENERALLY LOWER UPPER HEIGHTS THAN IN RECENT DAYS
WILL HELP HOLD DAYTIME READINGS DOWN A TAD...ALTHOUGH ACTUAL HIGHS
WILL CONTINUE TO RUN SLIGHTLY ABOVE NORMAL IN THE 90-95F RANGE.

MONDAY THROUGH WEDNESDAY...FOCUS TURNS TOWARD THE GULF OF
MEXICO...AS MODEL DIFFERENCES QUICKLY ARISE IN THE HANDLING OF
UPR LVL ENERGY AND RESULTANT SFC LOW DEVELOPMENT IN THAT REGION.
LATEST GFS AND ECMWF CONTINUE TO INDICATE UPR RIDGING TEMPORARILY
BUILDING BACK IN DURING THIS PERIOD...KEEPING CONVECTIVE
DEVELOPMENT CONFINED TO THE EXTREMELY ISLTD DIURNAL VARIETY WITH
PW VALUES CREEPING BACK UP TO AROUND 2.0"...AND MAINTAINING ABOVE
NORMAL DAYTIME TEMPS IN THE LOW/MID 90S. MEANWHILE...00Z NAM LIFTS
A STRONG SFC LOW INTO SOUTHERN MS...AND PUSHES A DEEPER SWATH OF
MOISTURE NORTHEAST TOWARD THE TN VALLEY. WHILE THE FORMATION OF A
LOW IS ALSO SUPPORTED BY THE GEM/UKMET...THE NAM APPEARS TO BE
SUFFERING FROM GRID SCALE FEEDBACK WITHIN THE QPF/MOISTURE
FIELDS...AND CONSEQUENTLY MAINTAINING COOLER DAYTIME TEMPS
(ESPECIALLY TUESDAY). GIVEN THESE ISSUES...AND THE FACT THAT THE
UPR RIDGE HAS BEEN THE PREDOMINANT FEATURE ALL SEASON...PREFER THE
WARMER/DRIER SOLUTION AT THIS TIME...AND WILL JUST TEMPER THE
DAYTIME WARMING SLIGHTLY DURING THIS PERIOD.

THURSDAY THROUGH SUNDAY...UPPER HIGH WILL RETROGRADE BY THE END OF
THE WEEK...WITH GENERAL TROUGHINESS/UPR LVL NORTHWEST FLOW
BUILDING ACROSS THE AREA. WEAK UPPER WAVES EMBEDDED WITHIN THIS
FLOW...COMBINED WITH A RETURN OF DEEPER MOISTURE...WILL ALLOW PCPN
CHANCES TO CREEP UPWARD INTO NEXT WEEKEND. STILL SOME INDICATION
OF A WEAKENING FRONTAL BOUNDARY MOVING TOWARD THE AREA IN THE
THU/FRI TIMEFRAME...WHICH COULD BE AN ADDED FOCUS. THUS...WILL
MAINTAIN ISLTD PCPN CHANCES THROUGH THIS PERIOD...WITH
TEMPERATURES SLOWLY TRENDING COOLER AND BACK CLOSER TO NORMAL.

&&

[Berwick Bay]

Yes the ridge will be breaking down in a few days. And that could signal "our time" along the N Central Gulf Coast--La-Miss-Al-Fl Panhandle. Its true that we do get our share of hits in Aug (witness Katrina-Andrew-Camille), however if you look back you'll see significantly more hits in Sept (as opposed to Tex). So the ridge will break down and as we move into Sep, I'm afraid its gonna be nail bitin' time again along the N Central Gulf Coast.

[Extremeweatherguy]

Yes the ridge will be breaking down in a few days. And that could signal "our time" along the N Central Gulf Coast--La-Miss-Al-Fl Panhandle. Its true that we do get our share of hits in Aug (witness Katrina-Andrew-Camille), however if you look back you'll see significantly more hits in Sept (as opposed to Tex). So the ridge will break down and as we move into Sep, I'm afraid its gonna be nail bitin' time again along the N Central Gulf Coast.

Actually, my area of Texas has seen more hits during the month of September than it has during the month of August. So, IMO, "N Central Gulf Coast" should include the region from Matagorda Bay, TX all the way to the Suwannee river in FL...not just LA, MS, AL and the FL panhandle.

I do agree though that September is looking potentially worse for the U.S. than August was. If another Dean comes along 2 weeks from now, then the chances of it heading due west into Mexico are very slim.

[Berwick Bay]

Perhaps you're right Extreme, in regards to the upper Texas Coast. And there have been very important Sept hits along the Texas Coast in general (1900, 1919, and 1961). But in the context of a ridge which is weakening or breaking down, then I think further east becomes prime real estate for landfall. I live in SW La. and even that may be a little too far west in this admittedly very general context. SE La to Fl Panhandle would seem to have the highest chances at this point. At any rate, I think that N Gulf Coast odds will go up significantly in the Sept 7- Oct 7 period.

[baygirl_1]

Is that the BOC low (Invest 93L) or another wave coming into the Gulf later this week? Check this out from the Mobile NWS forecast discussion:

000
FXUS64 KMOB 262027
AFDMOB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
330 PM CDT SUN AUG 26 2007

LONG TERM (WEDNESDAY THROUGH NEXT SUNDAY): NO CHANGES MADE TO
PREVIOUS LONG TERM PACKAGE. AS MENTIONED...HIGH PRESSURE BOTH SFC
AND ALOFT CONTINUES OVER THE REGION ON WEDNESDAY...BUT BEGINS TO
BREAK DOWN THU AND FRI PER GFS. ALSO NOTED POSSIBLE TROPICAL WAVE
MOVING INTO EASTERN GULF LATE WEEK AND INTO NEXT WEEKEND...BUT FOR
NOW IT LOOKS LIKE ANY EFFECTS FROM THIS WILL REMAIN TO OUR SOUTH.
WILL CONTINUE WITH MORE SEASONAL POPS AND JUST ABOVE NORMAL TEMPS
FOR MID WEEK INTO THE WEEKEND. 12/DS

Doesn't sounds like anything to get too worried/excited about, but something to keep an eye on...

[caneman]

LAtest 06 GFS run hints at some weak development here so we'll need to keep an eye on it.

[HeeBGBz]

Anything going on with the convection around 24n 87w?

[jasons2k]

Looks like a small surface circulation at ~27N 88W but so far most of the convection is to its SE