Posted: Wed Apr 18, 2012 11:58 am Post subject: Strong Gulf LOW this weekend.
The NAM, GFS, and Euro are forecasting a strong Gulf LOW to form this weekend. The NAM has the furthest south position while the GFS and Euro have it near the Panhandle and Big Bend area. Pressures range from 1000 mb to 1003 mb. Regardless, the weather will be going down hill with the potential for heavy rain, strong gradient winds, and nasty boating conditions with gusts reaching well into the gale force range. This system will be a slow mover and it will have good upper level support which means possible severe weather.
Posted: Wed Apr 18, 2012 12:01 pm Post subject: Re: Strong Gulf LOW this weekend.
CONDITIONS REMAIN BELOW HIGHLIGHT CRITERIA OVER THE NEXT FEW DAYS
EXCEPT IN THE VICINITY OF ANY THUNDERSTORM THAT MAY FORM WITH A
WEAKENING FRONT MOVING ACROSS THE EASTERN GULF TODAY. THEN BY FRIDAY
A STRONG MID LVL TROUGH BRINGS A ROBUST COLD FRONT BOUNDARY INTO THE
GULF AND THROUGH THE REGION FOR SATURDAY AND SUNDAY WITH POSSIBLE
WIND SPEEDS REACHING OR EXCEEDING THE 30 KNOTS RANGE AND SEAS WELL
ABOVE ADVISORY LEVELS. MARINERS MUST REMAIN WELL INFORMED ABOUT THIS
POTENTIAL HAZARDOUS WEATHER SCENARIO FOR THIS UPCOMING WEEKEND." _________________ LOU
Posted: Wed Apr 18, 2012 12:07 pm Post subject: Re: Strong Gulf LOW this weekend.
".LONG TERM...(Friday Night through Wednesday).
Challenging long term period of the forecast with the potential for
a very active early start to the period with an approaching storm
system on Friday night. Model guidance has been flipping and
flopping for the last few cycles now, but it appears that a trend is
emerging and the 18/00z guidance set has provided some much needed
clarity on the weather picture for this weekend. All of the guidance
is consistent on the pattern across the CONUS amplifying markedly
Friday night with a large trough digging into the Western Gulf.
Surprisingly, the GFS has been the more consistent of the available
guidance members with its forecast for the last couple of days, at
least on the 00z and 12z runs. The Euro seems to be going back and
forth between the more progressive solution offered by the GFS and a
much slower pattern that doesn`t match up well with the more
amplified pattern. This 18/00z model cycle is similar to the cycle
just 24 hours ago with the operational GFS and Euro nearly on top of
each other through 00z Monday. This more progressive pattern has
support from the 18/00z GFS ensemble mean as well as the 17/12z
ensemble mean. Though there are still differences, as is usually the
case at the day 4-5 timescale, enough consistency is present to
indicate a rather stormy weekend across the region with a
multi-faceted hazardous weather threat through Sunday.
Saturday/Sunday...As the potent upper level low plunges toward the
Gulf Coast on Saturday morning expect surface cyclogenesis to occur
rapidly across the Mississippi River Delta. With strong forcing for
ascent occurring across the Northern Gulf expect to see showers and
thunderstorms increasing throughout the day. As the surface low
rapidly deepens across the North Central Gulf, expect winds to
increase as well with gale conditions possible across the marine
area. Given the 36 to 48 hour duration of these strong southerly
winds, there is some concern of coastal flooding and minor beach
erosion due to high surf, though it is just a little too early to
pinpoint the placement and magnitude of this threat.
The severe weather potential appears to be increasing, particularly
because the surface low track may be more inland across Southern
Alabama and into Middle Georgia. This will keep much if not all of
the forecast area in the warm sector throughout the event, and given
the strong dynamical forcing and deep layer shear values, organized
severe storms are looking more likely." _________________ LOU
Posted: Fri Apr 20, 2012 3:21 pm Post subject: Re: Strong Gulf LOW this weekend.
"GFS/NAM/EURO ARE LOOKING A LITTLE BETTER IN TERMS OF OVERALL
SCENARIO FOR THE APPROACHING DEEP TROUGH AND MID LVL LOW/SFC FRONT
COMPLEX. TIMING ON ECMWF REMAINS AS THE MOST CONSISTENT DURING THE
LAST 12-24 HOURS...ALTHOUGH GFS/NAM HAVE COME A LITTLE CLOSE TO EACH
OTHER ON THE 12Z RUN. WINDS HAVE BEEN BASED ON 6 HOUR EURO...THEN
BLENDED FOR SPEEDS AND DIRECTION WITH NAM/GFS.
FOR SATURDAY...MODEL SOUNDINGS DEPICT DEEP LAYER MOISTURE IN PLACE
WITH PWATS NEAR 2 INCHES SAT AFTERNOON...TRIGGER TEMPS AROUND 78F
AND INCREASING VERT W/S AHEAD OF THE APPROACHING FRONT. THE LOW
ITSELF IS BROUGHT STRAIGHT THROUGH THE TAMPA BAY AREA BY SUN MORNING
VIRTUALLY BY ALL MODEL SOLUTIONS...WITH A VERY MOIST AIRMASS
SPREADING ACROSS THE ENTIRE STATE FOR MUCH OF SATURDAY. POPS
INCREASE TO 80 PERCENT EVERYWHERE SAT AFTERNOON WITH NUMEROUS
SHOWERS AND SCATTERED THUNDERSTORMS. BEST CHANCES FOR STRONG TO
SEVERE STORMS ARE NOW ACROSS THE TAMPA BAY AREA AND SOUTHWARD
THROUGH SAT NIGHT. SPC INDICATES A SLIGHT RISK FOR SEVERE STORMS
TAMPA BAY AND SOUTHWARD WITH POTENTIAL DAMAGING WINDS...LARGE HAIL
AND ISOLATED TORNADOES WITH THE STRONGEST CELLS.
ONE FEATURE NOW BEING CONSISTENTLY OBSERVED IN ALL THREE MODELS IS A
LAYER OF DRY AIR ENTRAINMENT INTO THE LOW CIRCULATION AND ERODING
SOME OF THE MOISTURE FIELD ACROSS THE SOUTHEASTERN EDGE OF THE LOW.
BUT GIVEN THE AGGRESSIVENESS OF THE MODELS IN TERMS OF OVERALL
POPS...WILL ASSUME THIS FEATURE IS NOT GOING TO HAVE A MAJOR IMPACT
ON THE POTENTIAL FOR HEAVY RAIN ACROSS THE AREA. RAINFALL ESTIMATES
BRING SOME 1-2 INCHES ACROSS THE CWA WITH POSSIBLE HIGHER AMOUNTS
WITH THE STRONGEST CELLS AND POSSIBLY OVER THE TAMPA BAY AREA AND
THE CENTRAL INTERIOR COUNTIES." _________________ LOU
Posted: Sat Apr 21, 2012 3:22 am Post subject: Re: Strong Gulf LOW this weekend.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
403 AM EDT SAT APR 21 2012
.SHORT TERM (TODAY-MONDAY)...
SHOWERS AND STORMS FROM AN UPPER SHORT WAVE WILL CONTINUE TO LIFT
NE AND MOVE OUT OF THE AREA THIS MORNING AS THE UPPER LOW DIGS
SOUTH INTO EAST TX. AS THE LOW MOVES OVER THE NORTHERN GULF COAST
THROUGH THE DAY TODAY...SURFACE LOW PRESSURE WILL ORGANIZE OVER
THE NORTH-CENTRAL GULF WITH MORE SHORT WAVE ENERGY AHEAD OF THE
SYSTEM ALLOWING FOR NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE
AREA TODAY. SOME STRONG TO ISOLATED SEVERE STORMS WILL BE POSSIBLE
WITH THE STORMS WITH STRONG WIND GUSTS AND HAIL. GOOD BENEFICIAL
RAINS WILL ALSO OCCUR WITH THE STORMS TODAY AND TONIGHT...WITH AN
OVERALL 1-3 INCHES POSSIBLE ACROSS THE AREA. WILL BE MONITORING
FOR ANY LOCALIZED FLOODING WITH THIS AS WELL. WILL ALSO HAVE A
MODERATE RISK OF RIP CURRENTS THIS AFTERNOON ACROSS AREA BEACHES
AS WINDS INCREASE AND BECOME MORE SOUTHWESTERLY ALONG THE COAST.
THE SURFACE AND UPPER LOWS WILL THEN MOVE OVER THE STATE SATURDAY
AFTERNOON THROUGH EARLY SUNDAY MORNING AND BRING THE BEST CHANCE
FOR SEVERE WEATHER ACROSS THE AREA WITH THE SQUALL LINE AND
UPPER LOW. THE AREA IS UNDER A SLIGHT RISK WITH DAMAGING WIND
GUSTS...LARGE HAIL AND ISOLATED TORNADOES POSSIBLE. THE HEAVY
RAINS WILL ALSO CONTINUE WITH LOCALIZED FLOODING POSSIBLE AND THE
RIP CURRENT THREAT WILL ALSO CONTINUE.
THE LOW PRESSURE SYSTEM WILL PUSH OFF TO THE NE SUNDAY...DRAGGING
THE COLD FRONT THROUGH THE AREA AND GRADUALLY CLEARING THE AREA
OUT. THERE WILL BE SOME LINGERING SHOWERS AND STORMS INTO SUNDAY
MORNING AND HAVE KEPT SCATTERED RAIN CHANCES...THOUGH LOWERED POPS
TO 40 PERCENT. HIGH PRESSURE WILL RIDGE INTO THE AREA FROM THE NW
BEHIND THE SYSTEM FOR SUNDAY NIGHT AND MONDAY. WILL BE MONITORING
WINDS FOR MONDAY AS THEY MAY APPROACH LAKE WIND ADVISORY CRITERIA.
ONSHORE FLOW MAY ALSO CONTINUE RIP CURRENT CONCERNS...ESPECIALLY
FROM PINELLAS NORTH AND WILL NEED TO MONITOR FOR HIGH SURF
CONDITIONS. _________________ LOU
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