TROPICAL DEPRESSION FRED / TROPICAL DISTURBANCE INVEST 91L FORECAST SYNOPSIS…ISSUED SEP. 04, 2015…1:55 P.M. EDT

TROPICAL STORM FORMATION: FRED, INVEST 91L

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: 6
HURRICANES: 2
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2

StormW’s Seasonal Forecast:

TOTAL STORMS:             8
HURRICANES:                   3
INTENSE HURRICANES: 1

Good day everyone!

Tropical Storm FRED, as of the 11:00 a.m. advisory from the NHC in Miami, has been downgraded to a Tropical Depression.  The following information was available on the depression at 11:00 a.m. EDT:

Location: 22.3°N 38.3°W
Moving: WNW at 9 mph
Min pressure: 1006 mb / 29.71 in
Max sustained: 35 mph

NHC TRACKING MAP
144740W5_NL_sm

FRED has been undergoing wind shear once again, and the LLC has been exposed to the west of the convection.  Based on the current wind shear forecast map from the GFS, I tend to agree with the NHC intensity forecast in the 11:00 a.m. Forecast Discussion.  The shear forecast does indicate upper level winds in the projected path of the depression, could become favorable again within 72 hours, with an upper level anticyclone once again developing.

NHC FORECAST DISCUSSION (WITH INTENSITY FORECAST)
http://www.nhc.noaa.gov/text/refresh/MIATCDAT1+shtml/041446.shtml

FRED FLOATER SATELLITE LOOP IMAGERY
avn0FRED-lalo

rgb0FRED-lalo

Based on my analysis of the current forecast steering layers maps, I concur with the NHC forecast track, which lies in agreement with the dynamic model guidance, which is tightly clustered.  This will be my last post on FRED.

Elsewhere, INVEST 91L was designated yesterday as it exited the west African coast.  Based on the 12Z ATCF FTP information, the following was available on the disturbance:

Location: 11.2°N 19.5°W
Moving: W at 15-20 mph
Min pressure: 1009 mb / 29.80 in
Max sustained: 30 mph

The disturbance has become slowly better organized during the past few hours.  Based on my analysis of the current wind shear product from CIMSS, upper level winds were favorable for further slow development of this disturbance.  Analysis of the wind shear forecast products from FSU and PENN State (GFS and CMC modeling), upper level winds are forecast to remain pretty much favorable for at least the next 96 hours, with the premise of an upper level anticyclone being maintained over the disturbance should it continue it’s current motion for the next 72-96 hours.  The NHC in the 2:00 p.m. EDT Tropical Weather Outlook designated a HIGH (70%) probability of cyclone formation during the next 5 days

NHC GRAPHICAL TROPICAL WEATHER OUTLOOK
two_atl_5d0

RAMSDIS-CIRA METEOSAT 4 FLOATER 91L
tropical_met_4km_ir4_floater

tropical_met_4km_visir2_floater

GFS 200 MB STREAMLINE FORECAST (INDICATING UPPER WIND PATTERN)
200 mb streamline
200 mb streamline2
200 mb streamline3
Albeit, based on water vapor floater imagery, it appears 91L has had a little bout with dry air, based on the forecast shear pattern, warm SST’s, and high TPW surrounding the system, I do believe the disturbance should be able to eventually mix out the drier air.  Kind of not unlike what we saw with Erika.

91L FLOATER WATER VAPOR SATELLITE LOOP IMAGERY
wv0-lalo

INVEST 91L TPW IMAGERY
tccapturetpw

Based on the combination of all these parameters, I do believe further slow development should occur, with possible development of a Tropical Depression within the next 24-36 hours, should this organization continue.  Convection has been noted flaring, just north of the center.  Some slight banding features appear to be trying to develop, mainly south of the center, as based on upper level satellite derived winds, this is where the strongest outflow channel is at the moment.  It is too early to tell how strong this disturbance may become.  Based on analysis of the 12Z AMSU and WINDSAT data, 91L did not have a closed LLC at the time.  The 12Z Intensity Guidance does bring this to tropical storm status within 4 days, based on both the majority, and the more accurate modeling.  However, THIS IS TO BE CONSIDERED PRELIMINARY, as early runs of these models, when a system does not have a closed LLC, are not to be deemed as accurate.

WINDSAT DATA
WMBas32_noaa

ATCF 12Z 91L INTENSITY GUIDANCE
91L 12Z INTENSITY GUIDANCE
The disturbance is currently moving in a westerly fashion, or just north of due west, based on the ATCF FTP information, satellite loop imagery, and current shallow layer steering.

CURRENT STEERING LAYER MAP
wg8dlm1

Based on my analysis of the current run of the forecast steering layers maps, valid for 00Z this evening, I expect this motion to continue during the next 72 hours, with maybe more of a bend to due west thereafter, as the subtropical ridge expands westward and strengthens somewhat on it’s extreme southern periphery.  This tends to coincide with the ATCF 12Z Dynamic Model guidance, in which I am leaning toward the TVCN-TVCC consensus models.  Again, this should also be considered PRELIMINARY, as strength of the system will determine which layer the system is steered by, and should also be considered PRELIMINARY, as the models currently have no LLC to track.

INVEST 91L ATCF 12Z DYNAMIC GUIDANCE (BOTTOM SET OF MODELS)
91L 12Z DYNAMIC GUIDANCE

I will continue to monitor this disturbance for any significant changes to strength and track during the next 72 hours. 

I am also curious in another tropical wave over the African continent.  Right now, the CMC model is the only one indicating development of this.  The wave in question is circled in yellow.

EUMETSAT LOOP IMAGERY
EUMETSAT_MSG_RGB-dust-all

Elsewhere, Tropical Storm formation is not expected during the next 5-7 days.

Have a blessed day!

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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5 Responses to TROPICAL DEPRESSION FRED / TROPICAL DISTURBANCE INVEST 91L FORECAST SYNOPSIS…ISSUED SEP. 04, 2015…1:55 P.M. EDT

  1. dellamom says:

    It would appear that Fred, having visited the Cape Verde islands and finding that he liked island life, may be attempting a visit to the Azores, given the forecast path

  2. dellamom says:

    Thank you, Storm.

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