TROPICAL WEATHER OUTLOOK…EVENING EDITION…JUNE 20, 2103…ISSUED 7:20 P.M. EDT…PHFC

Good evening!

As promised earlier, the outlook of the premise for future storm development in the Caribbean / GOMEX during the first week of July.

Analysis today revealed some positive factors that indicate another possible Tropical Storm development IVO where Tropical Storm Barry just came from.  These factors are the same that bore both Andrea and Barry.

The GFS has been fairly consistent so far in indicating another development at the very end of the month, to first week of July.  Using the mean of the runs, we’ll say close to July fourth.  The GFS starts this out in almost the exact area the INVEST for Barry was located.  The model starts this around the 28th, and moves it NW across the Yucatan Peninsula, then into the GOMEX, targeting the LA/TX area.  As far as exact track, this should be taken with a grain of salt right now, however, as far as cyclogenesis, I will not rule this out, as the GFS thus far is 2 for 2 on detecting cyclogenesis at 2 weeks out.

GFS SOLUTION

Another item that supports this, is the current forecast of the NCEP Ensemble 500 mb anomaly departure.  A significant lowering of pressures is forecast within the the forecast time mentioned.

NCEP 500 MB ANOMALY DEPARTURES

Analysis of MJO forecast products indicates a fairly moderate to strong upward motion phase of the MJO (Madden-Julian Oscillation).  This promotes upward vertical velocities and moisture in the atmosphere.  In the index forecast, the first graphic, I have drawn the favored areas of Octants 8 and 1 for development in the GOMEX and Caribbean.

MJO INDEX FORECAST

ECMWF

GEFS

UKMET

GEFS BIAS CORRECTED

MJO OLR FORECAST (BLUE SHOWS UPWARD MOTION)

The current wind shear forecast from the GFS medium and long range forecast times indicates a fairly large and well established upper level anti-cyclone that develops weakly in the very first stages of the system shown, but moves in tandem, becoming better established over the GOMEX in that portion of the forecast period.  One note on the shear forecast…as the upper level anti-cyclone moves in tandem, the zero line (Purple line) remains pretty much over the center of the system throughout its trek.  IF all of these factors come together as shown, the GFS may be underestimating strength of this possible Tropical Storm.  I am posting the times which coincide with the GFS output showing the system so you may see where the zero line is in relation to the storm

GFS ZONAL SHEAR

192 HOURS

240 HOURS

276 HOURS

I will continue to monitor subsequent runs on the Global Models, Wind Shear forecast, and any significant changes to the MJO pattern.

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