TROPICAL WEATHER FORECAST SYNOPSIS AND DISCUSSION…MON. AUG. 12, 2013…ISSUED 12:20 P.M. EDT…PHFC

Good day everyone!

Still somewhat quiet in the tropics as of  this morning’s analysis.

I am currently monitoring an increase in thunderstorm activity just NE of the Isthmus of Panama.  This activity is in association with a partial extent of the EPAC Monsoon trof, and a surface trof moving through the Caribbean Sea.  Both features can be noted in the 06Z NHC Surface Analysis Map.

NHC 06Z SURFACE ANALYSIS MAP

WATL SATELLITE LOOP IMAGERY

Albeit satellite loop imagery indicates the main area of cyclonic turning to be over the Isthmus, 850 mb vorticity has become more prominent just north of this landmass.

CIMSS 850 MB VORTICITY MAP

Currently, the wind shear map from CIMSS shows around 15-20 knots of westerly shear over the area at the moment.  However, the current wind shear and zonal shear forecast maps indicate upper level conditions may improve over the next 12-18 hours, with an upper level anticyclone projected to develop over the area.  Wind shear has decreased somewhat over the past 24 hours directly over the area.

CIMSS CURRENT WIND SHEAR AND TENDENCY MAPS

Analysis this morning of Global Models tends to indicate we may see development out of this feature, which I have been speaking of over the past few days.  Model suggestions are anything from a tropical depression, to a mid grade tropical storm at possible landfall.  Three of the models giving this indication are the GFS, CMC, and the FIM Experimental model.

GFS MODEL
06zgfs500mbHGHTPMSLtropical126 (1)

CMC MODEL
00zggem500mbHGHTPMSLtropical156

FIM MODEL

I cannot rule this out, given that we have conditions as mentioned.  And based on the supposed track, the upper level anticyclone I mention, may move with anything that may develop.  So, based on this, and current and forecast steering layers maps, I believe a good probability exists for development of this area.  The NCEP/EMC Ensemble output indicates a high probability at the moment for this area to develop during the next 48-120 hours.

NCEP/ECM MAPS

12Z SREF

06Z MULTI MODEL AND NCEP ENSEMBLE

Should we see development, right now based on forecast steering, I would expect this to enter the Southern GOMEX in a few days, and would prefer the track presented by the FIM, albeit a little more toward the west (Central LA?).  As a reminder, this is conjecture at best right now, being we have nothing that is developed.  In fact, since the models have been so quiet, I am going to be forecasting mainly on a real time basis through analysis of various items, and take things from there on a daily basis.

I will continue to monitor this area for any significant changes during the next 96 hours.

Elsewhere, the area of low pressure that moved off the African Coast previously, has pretty much been affected by some drier air.  However, I will be monitoring the next MCS over Africa at the moment as it moves into the Atlantic.  Indications seem to be, that the upper level environment may improve as this moves off the continent.

EUMETSAT_MSG_IR108Color-westernAfrica (1)

EUMETSAT SATELLITE LOOP

I realize it’s been very quiet so far, since the demise of Dorian.  However, based on various items analyzed almost daily, we seem to have more favorable parameters pointing toward and above average season.  A couple of factors that have been detrimental thus far, is the SAL outbreaks we experienced near the end of July, and earlier this month.  Another is, the Azores Bermuda high has been hovering around 1028-1030 mb (30.36-30.42 in), although there have been constant fluctuations, for the most part, the high has been relatively stronger longer than it has been near average.  This does a few things in the MDR.  Given where the SAL has been originating from (well over N and E Africa), the dust has been picked up by the stronger NE winds, and carried across the Atlantic.  With the high being stronger, sinking air is much greater.  As this air sinks, which is what happens with high pressure cells, air compresses, warms, and dries out the atmosphere…hence the lack of instability in the Tropical Atlantic.

The stronger the high, the quicker the surface winds…which doesn’t allow for lower level convergence to take place, in addition, any surface feature would have the tendency to “outrun” slightly, any associated convection.  The stable atmosphere can be noted in RGB satellite loop imagery as indicated by the Stratocumulus cloud deck east and NE of the Cape Verde Islands.

RGB SATELLITE LOOP IMAGERY

As I stated earlier, I do believe activity will pick up, albeit not until around the third week of the month, possibly very close to around 25-28 Aug. I am going to attribute this on one lone forecast parameter at the moment, should the forecast pan out.  The majority of the Dynamic Models indicate a return of an upward motion phase of the MJO by the time mentioned.  Instead of posting all the model graphics, here is the forecast OLR (Outgoing Longwave Radiation) projections for the MJO, with blue being upward motion, or upward vertical velocity, and lighter greens and then orange, representing downward motion, or downward vertical velocity.

OLR FORECAST

Tropical Storm formation is not expected during the next 48 hours.

Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)
CoCoRaHS OBSERVER

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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6 Responses to TROPICAL WEATHER FORECAST SYNOPSIS AND DISCUSSION…MON. AUG. 12, 2013…ISSUED 12:20 P.M. EDT…PHFC

  1. dellamom says:

    Thanks, Storm. One of the local TV weather websites had mention of something in the caribbean possibly developing, so I clicked over to your site to check your report, but when I clicked back that report was gone and now I don’t see it anywhere. Wierd and kind of sad. If they’d have left it up, it would have had more people watching the tropics instead of figuring the season was going to be smooth sailing. You’d be surprised (or maybe not) at how many people think that since we have not had anything yet, we won’t. I then mention that Betsy, the second worst hurricane to hit New Orleans in the past 50 years, wasn’t until September 7-9, and it was only a “B” storm. We have already had “D” and it is only early August. That usually gets them thinking …

  2. stefanie says:

    Thanks Storm. 🙂

  3. Alicia Lindsey says:

    Thank you for the update.

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