SPECIAL TROPICAL WEATHER DISCUSSION / REVISED SEASONAL HURRICANE FORECAST…ISSUED MAY 09, 2017…4:40 P.M. EDT

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(T. F. “Storm” Walsh III)

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Good day everyone!

I will be focusing on the coastal storm that is forecast for this weekend, in tomorrows forecast.  I did however want to touch once more on the EPAC system.  INVEST 90E has continued to become much better organized, and a definite, closed LLC is noted with the aid of ASCAT imagery.  Satellite loop imagery did indicate the presence of overshooting tops within various locations of the system, indicative of a strengthening system.

RAMSDIS SATELLITE LOOP IMAGERY

Upper level winds are conducive for further development, with the wind shear forecast indicating a favorable upper level environment during the next 5 days.  The NHC issued a special update, and may begin advisories later today.

Guidance indicates the initial motion over the next 3 days to be WNW to NW, and the majority of track guidance brings this system to landfall over a mountainous region.  As I have stated earlier, I’m not really counting on a crossover right now, as the mountain heights reach between 4500-6600 ft, which should quickly disrupt the circulation, unless this storm becomes a very intense hurricane.  Current intensity guidance brings it to near CAT3 status, however, this may be a little overdone, which is common for initial guidance. I’ll be checking in now and then on this system, just to be sure.

INITIAL TRACK GUIDANCE

Having received updated information from the climate models, I wanted to update my  2017 Seasonal Hurricane Forecast.  Original forecasts from earlier in the year, indicated a good probability of the onset of an El Nino.  However the trend over the past 3 months has been downward IRT to the Nino 3.4 forecast plumes.

NINO 3.4 FORECAST PLUMES

Current runs of SST anomaly maps also indicate a possible weak El Nino in region 3.4, however the runs also indicate cooler Nino 1 and 2 anomalies, and warmer Nino 4 anomalies in relation to the Nino 3.4 region, also verified in the Nino plumes.  What this basically describes is the onset of an El Nino Modoki.

CFSv2 SST ANOMALY FORECAST FOR JAS – ASO

NINO REGION 1 + 2, AND 4 PLUMES

Wind shear over the MDR is forecast by the CFSv2 to be below, to within climatology during JUL – OCT.

CFSv2  u200 – u850 (WIND SHEAR)

I could get in trouble for posting the following, BUT, felt it important…so this is a one time shot… the ECMWF Seasonal forecast model is also in agreement with the CFSv2 SST.  The forecast pressure pattern would tend to indicate weaker easterlies in the MDR, as well as a probability for an increase in U.S landfalls

The following is from “colleague” Joe Bastardi of Weatherbell Analytics regarding this:
A look at the SST shows a weak to perhaps moderate enso 3.4 el nino, but a cooler 1.2 and a warm MDR in the Atlantic basin. This is not unlike the 2004 el nino, which I did not incorporate into the totals but may have to now in the update.  In addition the MSLP is one that has my attention for hits even more now that belt of higher pressures north of 40 north is a big deal. The core of the higher pressures has shifted out of the MDR.

ECMWF SEASONAL MSLP FORECAST
Based on the new analysis of the climate models trend, I referenced the ONI using a blend of both Nino 3.4 values and trends, and past SST anomaly maps and information, I came up with 1951, 2002, and 2004 as the analog years.

SST ANOMALY MAPS FOR 2002 AND 2004

Having researched information this afternoon, I have to discard 1951, as it was defined as an El Nino season.  This leaves the two best, based not only the ONI, but comparison SST anomaly maps as far as a Modoki setup.  Based on the average of these analog years and other factors (such as the MDR is still not forecast to reach 2004 levels by both the CFv2 and ECMWF Seasonal forecast), should a Modoki setup take affect, I worked out the following new totals for this coming hurricane season.  Hurricane season 2002 came in at 12-4-2, and 2004 with 15-9-6.  Please note however, if modeling keeps fluctuating, and turns back the other way, my previous forecast could apply.

NEW 2017 SEASONAL HURRICANE FORECAST
Named Storms: 12-15
Hurricanes: 6-7
Major Hurricanes: 3-4

OLD SEASONAL FORECAST
Named Storms: 10 – 12
Hurricanes: 4 – 5
Major Hurricanes: 2

I will begin issuance of my Atlantic Tropical Weather Outlook Synopsis on May 15, 2017

If you have any questions regarding tropical storms and hurricanes, don’t be afraid to ask here, or on my Facebook page:
https://www.facebook.com/groups/636421683206277/?ref=bookmarks

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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2 Responses to SPECIAL TROPICAL WEATHER DISCUSSION / REVISED SEASONAL HURRICANE FORECAST…ISSUED MAY 09, 2017…4:40 P.M. EDT

  1. dellamom says:

    Thank you, Storm.

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