POST TROPICAL STORM HERMINE / INVEST 92L FORECAST SYNOPSIS…ISSUED SEP. 05, 2016…11:40 A.M. EDT

TROPICAL CYCLONE FORMATION: POST TROPICAL STORM HERMINE /INVEST 92L

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(T. F. “Storm” Walsh III)

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CURRENT 2016 ATLANTIC TROPICAL CYCLONE TOTALS:

TOTAL STORMS: 8
HURRICANES: 4
MAJOR HURRICANES: 1
U.S.LANDFALLS: 3

StormW’s Seasonal Hurricane Forecast:
TOTAL STORMS: 13-15
HURRICANES: 6-7
INTENSE HURRICANES: 3-4

Good day everyone!

HERMINE remains a very large Post Tropical Cyclone. As of the 11:00 a.m. EDT advisory, the following was available on HERMINE from the NHC:

11:00 AM AST Mon Sep 5
Location: 38.8°N 68.8°W
Moving: NW at 6 mph
Min pressure: 998 mb
Max sustained: 70 mph

NHC TRACKING MAP
143853W_NL_sm

NHC WATCH/WARNING MAP
HERMINE.WWsm

NHC 5 DAY WIND SPEED PROBABILITY LOOP
HERMINE.WINDSPEEDPROB

HERMINE continues to drift slowly to the NW, and this motion is expected to continue through the day.  Forecast steering suggests that the surface center and mid-upper level low will rotate around each other in a counter-clockwise fashion, becoming vertically stacked in about 24-36 hours, which may bring HERMINE a little closer to the coast, before steering suggests a NNE to east motion to resume in about 48 hours.

IF this becomes vertically stacked, one would believe this wold indicate the system could intensify and try to transition briefly to a more tropical state, as the upper level pattern is forecast to become very diffluent.  However, given that the cyclone is over much cooler waters of 23-25C (73-77F), these SST’s are indicative of only supporting extra-tropical to sub-tropical systems.

A Tropical Storm WARNING remains in effect, and the following are links to local NWS office statements.

NWS LOCAL STATEMENTS
http://www.nhc.noaa.gov/text/WTUS81-KOKX.shtml

http://www.nhc.noaa.gov/text/WTUS81-KBOX.shtml

The following map is linked for up to date NWS information.  Click on your area, or area of interest for the latest NWS Warnings and statements.

NWS WARNINGS DISPLAY
US

Elsewhere, I am still monitoring INVEST 92L as it moves west in the Caribbean Sea.  As of the 8:00 a.m. EDT ATCF BTK product, the following was available on INVEST 92L:

8:00 AM EDT Mon Sep 5
Location: 14.5°N 65.2°W
Moving: W at 22-25 mph
Min pressure: 1009 mb / 29.80 in
Max sustained: 40 mph

The disturbance continues to move toward the west at a fairly robust forward speed.  Based on my analysis of current and forecast steering layers maps, I expect this motion to continue through the next 72-96 hours.  The latest model guidance of the consensus models tend to indicate a dive toward the WSW in about 72 hours, however a couple of the global models, and the forecast steering products tend to discount this at the moment.  Based on this, I am currently calling for a continued westward motion through day 4-5. Thereafter, steering suggests the system could begin to gain some latitude, as steering appears to shift sharply to the NW for a brief period, and then weaken.  At this particular point in time, it is unknown if whatever this may or may not become, enters the GOMEX past day 5.  Up to that point however, I do believe this will cross over the Yucatan Peninsula somewhere near or north of Belize.

ATCF 92L DYNAMIC GUIDANCE FROM 12Z
92L. 12Z DYNAMIC

After having a brief run yesterday evening of becoming slightly better organized, INVEST 92L has seen convection wax and wane over the past few hours.  Albeit the convection appears fairly consolidated, the reported center is just to the WSW of the heaviest convection.  Based on my analysis of water vapor image loops, it does not appear that dry air is a problem as of yet, and the INVEST is still in an environment of high TPW.

INVEST 92L FLOATER SATELLITE LOOP IMAGERY
avn0-lalo.92L

rgb0-lalo.92L

The current problem is, it is outrunning the somewhat favorable upper level environment it had yesterday evening, and is now encountering some SWLY wind shear on the order of around  20-25 knots, as it has become positioned closer to the upper level low (ULL) to its west.

CIMSS WIND SHEAR PRODUCT
wg8shr

The quick forward motion (almost 5 degrees west motion in 12 hours), seems to be one of the hindering factors in lack of organization.  With the lower level steering being so quick, this doesn’t allow for surface convergence to occur.  However, based on my analysis of the current forecast steering, I am expecting the INVEST to slow its forward speed in about 48 hours.  This may begin to help in some slow organization at that point.

Based on analysis of both the GFS and ECMWF wind shear forecast products, upper level winds appear to remain marginal during the next 36-48 hours.  Shortly thereafter, both models are in fair agreement of re-establishing an upper level anticyclone over the system from about the 60-72 hour point in the forecast period.  IF the INVEST can survive the current conditions, I believe we should begin to see improvement once the system reaches the central and western Caribbean Sea, as the TPW is forecast to remain high, and the system will be entering an area of some very high OHC.  By all rights, should it make it through the current shear conditions, we should see some development once it reaches the area mentioned, as based on what the current model runs indicate in regard to the parameters mentioned, they point toward favorable conditions.  In fact, the SHIPS, DSHP, LGEM and IVCN intensity guidance models bring the system to minimal tropical storm status by the time it reaches the Yucatan Peninsula.  I cannot rule this out totally at the moment, however again, at this point and time with a disorganized system, track and intensity guidance should be deemed preliminary.

GFS 72 HOUR WIND SHEAR FORECAST
gfs_dl_shear_carib_13
CIMSS OHC PRODUCT
tccaptureOHC.92L

GFS TPW FORECAST
gfs_pwat_carib_13

I will continue to monitor this system for any significant changes over the next 2-3 days.

Elsewhere, at the moment, I am unclear as to which tropical wave the NHC is mentioning in their 5 day graphical tropical outlook.

NHC 5 DAY GRAPHICAL TROPICAL WEATHER OUTLOOK
two_atl_5d0

Satellite loop imagery indicates one wave south of the Cape Verde islands, and another right on the African coastline.  The first is located approximately near 7.0N;25.0W.  This wave is under marginal conditions at the moment, but is under a diffluent flow aloft, which will tend to enhance convection.  The wave along the coastline, is currently under somewhat favorable conditions with a partial upper level anticyclone overhead, and a marginal upper outflow pattern.  It is unclear which one of these may develop, however based on the wind shear forecast, the upper level pattern is forecast to improve during the next 72-96 hours.  I will be monitoring this area as well over the next few days.

METEOSAT SATELLITE LOOP IMAGERY
avn-l.meteosat

I should have another update tomorrow.

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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3 Responses to POST TROPICAL STORM HERMINE / INVEST 92L FORECAST SYNOPSIS…ISSUED SEP. 05, 2016…11:40 A.M. EDT

  1. dellamom says:

    Thank you Storm. Prayers your way, LT.

  2. greg goodman says:

    Thankyou mr storm for the update.Mr storm since we are in September now if anything develops how do you think the steering pattern might set up.I know you don’t like going out about 5 days but I was just curious.do you think the east coast or gulf coast.

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