INVEST 99L FORECAST SYNOPSIS…ISSUED AUG. 16, 2018…11:05 P.M. EDT

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(T. F. “Storm” Walsh III)

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StormW’s 2018 HURRICANE SEASONAL FORECAST

TOTAL STORMS: 12 – 13
HURRICANES: 5 – 6
MAJOR HURRICANES: 2 – 3

2018 CURRENT SEASON TOTALS

TOTAL STORMS: 5
HURRICANES: 2
MAJOR HURRICANES: 0

Greetings everyone!

The non tropical low that was meandering  over the far N. Atlantic, attained sub-tropical characteristics, and was named Ernesto.  Ernesto is no threat to land as it continues to move off to the NE at 18 mph.

Elsewhere I am monitoring a tropical wave, which I believe is the one I circled in my last update, which now has some limited convection,and is further west  At 00Z this evening the wave was located near 10.2°N and 52.2°W. The current intensity was 30 mph and the center was moving to the west at 15 mph. The minimum central pressure was 1013 mb, or 29.91 inches.

NHC 5 DAY GTWO (LINKED FOR OUTLOOK TEXT)

RAMSDIS FLOATER SATELLITE LOOP (CLICK IMAGE FOR LOOP)

Based on my analysis of current and forecast wind shear charts, 99L could slowly strengthen and may become a little better organized during the next 48 hours.  Current wind shear is only somewhat conducive, as the disturbance remains south of a semi upper level anticyclone.  The configuration is not optimal, however may be conducive for slow organization. The wind shear forecast from the GFS indicates that the upper level feature may remain slightly ahead of 99L, but tends to indciate shear values may relax to lower values.

CURRENT AND FORECAST WIND SHEAR

GFS SHEAR FORECAST


The current SHIPS diagnostic report indicates this, with shear values increasing over the next 18 hours, then dropping to somewhat favorable levels.  I do not foresee any appreciable change to the upper level feature, so it may be the fact that shear values will be fairly favorable.

SHIPS DIAGNOSTIC REPORT
http://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2018/al992018/stext/18081700AL9918_ships.txt

I am a little perplexed at the moment, as to why intensity guidance indicates this becoming a tropical storm within 48 hours.  The upper level pattern may not be optimal, and the models indicate some drier air out in time near 5,000 ft, and at the 700 mb level.

00Z INTENSITY GUIDANCE

RELATIVE HUMIDITY FORECAST 850 AND 700 MB LEVELS ECMWF MODEL

So it will be a matter of wait and see, but at this time, I only expect slow organization and strengthening over the next 24-36 hours.

Based on analysis of current and forecast steering layers maps, 99L should continue to move on a due north of west, to WNW motion during the next 36-48 hours, before a more WNW motion occurs.  Based on this, I concur with the NHC forecast hatched area in the 5 day outlook map above, however I am on the southern portion of current track guidance.

RAL 00Z TRACK GUIDANCE

I’ll continue to monitor everything, but with my job and all, will only be updating on my time off, unless we have a threatening system.

Have a blessed evening!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER

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