TROPICAL STORM HENRI / TROPICAL ATLANTIC QUICKCAST SYNOPSIS…ISSUED SEP. 10, 2015…9:00 P.M. EDT

TROPICAL STORM FORMATION: HENRI

ALL forecasts contained on this site,  are based on my analysis and knowledge of various forecast tools, including information contained in NHC products, and are not copies from any other entity.

*NOTE: In the TROPICAL STORM FORMATION line above, probabilities are for during the next 5 day period.  My personal probability will be listed as either NONE, MONITORING or PROBABLE.  This does not necessarily mean something will develop, but that certain forecast conditions are likely to be present, favoring development.  Once NHC products become available, then the appropriate probability and percentage will be used.

Please refer to the link for the Storm Prediction Center in the box at the top of the page, just below the Hurricane Hunter graphics.

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Current Storm Total for 2015:

TOTAL STORMS: 8
HURRICANES: 2
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2

StormW’s Seasonal Forecast:

TOTAL STORMS:             8
HURRICANES:                   3
INTENSE HURRICANES: 1

Good evening everyone!

This will have to be short, as I just got home from work about 6:00, and I’m beat!  Hence the “quickcast” in the title.

T.D. 8 became Tropical Storm HENRI yesterday.  As of the 5:00 p.m. advisory from the NHC, the following was available on HENRI:

5:00 PM AST Thu Sep 10
Location: 33.9°N 60.7°W
Moving: N at 15 mph
Min pressure: 1008 mb / 29.77 in.
Max sustained: 40 mph

NHC TRACKING MAP
203439WHENRI_NL_sm

Satellite loop imagery indicates the LLC of HENRI is exposed well to the SW of the convection.  This is attributed to some southerly wind shear which was noted in analysis this evening.

HENRI FLOATER SATELLITE LOOP
avn0HENRI-lalo

swir0HENRI-lalo

CIMSS  WIND SHEAR

tccaptureshear

The NHC forecast discussion indicates the shear may relax somewhat tonight, which “could” allow for some slight strengthening, albeit very briefly.  However, based on my analysis of the 12Z wind shear forecast map, the upper level pattern may not be optimal enough for strengthening, unless what is mentioned in the discussion of HENRI beginning to resemble a subtropical system, in which that some slight strengthening could occur, as the forecast flow would not affect HENRI as much in being subtropical.  Based on this, I tend to agree with the NHC intensity forecast, although personally I am leaning toward a Status Quo system, until weakening begins.

Based on analysis of the current forecast steering layers maps, I concur with the NHC forecast track, which is in the center of the dynamic guidance.

ATCF 18Z DYNAMIC GUIDANCE
HENRI 18Z DYNAMIC GUIDANCE

Elsewhere, another well defined Tropical Wave is abut to leave the African continent, and is displaying a pronounced cyclonic rotation.  Convection is limited at the moment, however upper level winds are favorable for development at the moment, with the most recent wind shear forecast indicating upper level winds to remain conducive for slow development during the next 48-60 hours.  Soon thereafter, upper level winds may only be marginal.

RAMSDIS METEOSAT 4 SATELLITE FLOATER LOOP IMAGERY
tropical_met_4km_ir4_floater

tropical_met_4km_visir2_floater

There is some dry air present, but is very limited at the moment, based on analysis of water vapor imagery products.  Current MIMIC TPW loop indicates a moderate to high TPW associated with the wave.  IF the analyzed forecast parameters hold, we should see slow development of this wave during the next 72 hours.  At the moment, it is to early to speculate as to whether or not we would see a depression by then, although the NHC has increased the 5 day probability from 20% to 30% in the latest TWO.

EATL WATER VAPOR IMAGE
wv-l

MIMIC TPW LOOP
latest72hrs
I will continue to monitor this wave closely during the next 72-96 hours for any significant changes.

Elsewhere, the ECMWF model has backed off in strength and size of a possible low in the BOC in a few days.  The ECMWF and CMC pretty much agree on a very small, weak low now in the BOC in about 5 days.  The GFS, NAVGEM, and UKMET are not impressed, however tend to hint at lower pressure.  Again, this doesn’t mean a development is for sure, as I’ve explained previously.  However, if one looks at the models closely, each model pretty much indicates high pressure over or near the Virginia area.  When surface pressures are high, or should I say, rise over an area in such a location, it is good to pay attention south of the area, in this case over the W. Caribbean, or in this case with the “hints”, over the BOC, as pressures south of the high tend to lower, which is a natural occurrence of what we term the PGF (Pressure Gradient Force).  This type of setup can lead to what we term as a “situational development”.  I’ll post a very simple explanation of PGF after the global model graphics.  I will keep tabs on the BOC next week as a precaution.

ECMWF
ECMWF120
CMC
CMC.120
GFS
GFS
NAVGEM
NAVEGM
PRESSURE GRADIENT FORCE
http://ww2010.atmos.uiuc.edu/%28Gh%29/guides/mtr/fw/pgf.rxml

Elsewhere, Tropical Storm formation is not expected during the next 7 days.

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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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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2 Responses to TROPICAL STORM HENRI / TROPICAL ATLANTIC QUICKCAST SYNOPSIS…ISSUED SEP. 10, 2015…9:00 P.M. EDT

  1. originallt says:

    Thanks, Storm. Another “weak” system, Henri. I wonder , if many years ago, this system would have even been noticed–along with one or two other ones this year? These type of systems, “inflate” the # of named storms, in my opinion. In the NLF, we had, “Deflate Gate” in the NHC, we may have, “Inflate Gate”!

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