ENHANCED SEVERE WEATHER RISK / TROPICAL WEATHER OUTLOOK FORECAST SYNOPSIS…ISSUED MAY 17, 2017…12:35 P.M. EDT

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(T. F. “Storm” Walsh III)

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Good day everyone!

The SPC has designated the following severe weather risk areas in the Day 1 Outlook as of the 1630Z issuance:

…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF IA…SOUTHEAST MN…SOUTHWEST WI…AND SMALL PARTS OF NORTHWEST IL AND NORTHERN MO…

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENH RISK AREA…

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENH AND SLGT RISK AREAS…AND EXTENDING SOUTHWARD ACROSS THE OZARKS AREA…

…SUMMARY…
Severe storms are expected to develop this afternoon from the Mid Missouri Valley into Wisconsin. A few tornadoes, large hail, and strong wind gusts are possible. Farther south, at least a marginal severe risk will extend south across southern Missouri and possibly into Arkansas.

SPC DAY 1 CONVECTIVE OUTLOOK MAPS

Based on analysis of forecast sounding data from F5 DATA software, utilizing the RAP model, along with analysis of the SPC outlook text, the RAP suggests the strongest of the severe weather may initiate as early as 2:00p.m. EDT (1:00 p.m. CDT) over Iowa.  Sounding indices and values indicate the strongest severe weather, especially tornadoes, may occur between 5:00 p.m. – 8:00p.m. EDT in the outlined areas in the following maps.

F5 DATA RAP MODEL 2:00 P.M. – 5:00 P.M. EDT SOLUTION

F5 DATA RAP MODEL 8:00 P.M EDT SOLUTION

Tornado activity is probable within the 5% area in the SPC map, however near 7:00 – 8:00 p.m. EDT, the RAP model is suggesting a shift almost due east for probable tornadic activity.

Residents in the outlined SPC ENHANCED and SLIGHT risk area, should monitor NOAA Weather Radio, and local NWS statements for up to date information regarding any necessary actions.

IF A TORNADO WARNING IS ISSUED FOR YOUR AREA…SEEK SHELTER IMMEDIATELY!

The following graphics are linked to their respective sites.  Mouse over and click on the graphics for up to date information.

SPC CONVECTIVE WATCH DISPLAY

SPC MESOSCALE DISCUSSIONS DISPLAY

NWS DOPPLER RADAR SITE MAP

INTELLICAST RADAR SUMMARY (Click local area once map displays to zoom in)

NWS HAZARDS AND WARNINGS DISPLAY (click on graphic, then your area of interest)

TROPICAL WEATHER OUTLOOK

Analysis of satellite imagery and forecast normalized MSLP anomaly maps from both the ECMWF and GFS indicates the trof of lower pressure I had discussed yesterday, still remains in the W. Caribbean Sea.

RAMSDIS FLOATER SATELLITE IMAGERY LOOP (CLICK IMAGES FOR LOOP)

GFS MSLP NORMALIZED ANOMALY MAPS

Convection has increased slightly, however this is not due to organization, but to the diffluent flow aloft, east of the trof axis (this acts of somewhat as a lifting mechanism).  The area of low pressure itself is well west of the convective area, as 25-30 kts of wind shear is noted, blowing the convection away from the broad, and almost non discernible low level open circulation.

Drier air was noted in water vapor loop imagery to be moving into the area was well.

RAMSDIS WATER VAPOR LOOP

Based on my analysis of current and forecast wind shear products, I am not concerned about any development in this area, as upper level winds are forecast to remain unfavorable for development during the next 5-7 days.

CURRENT WIND SHEAR MAP FROM CIMSS

In about 7 days however, there is some disagreement between the ECMWF and GFS, in that the ECMWF eventually indicates pressure anomalies rising over the Caribbean, while the GFS indicates an area of moderate lowering of pressure anomalies.  At this time, I am more inclined to favor the ECMWF as none of the models indicates any type of development during that time.  However, it is noted that the GFS shows upper level winds becoming favorable, with an upper level anticyclone developing over the Nicaragua and Gulf of Honduras area.  I doubt if any development is likely, however this may be an area to keep tabs on should upper level winds become favorable…just as an area of interest.

GFS MSLP NORMALIZED ANOMALY AND WIND SHEAR FORECAST MAPS

As far as the status in the overall scheme of things, I am still expecting the SOI to continue to trend upward, and still expect to see some cooling in the NINO 1 & 2 region probably by months end.  Both the MJO forecast and CHI 200mb Vertical Velocity forecast for the next 2 weeks, indicates downward vertical velocities, or sinking air over the EPAC, and upward vertical velocities, or rising air over the WPAC and Australia region.  This should cause trades to flow from east to west, and may allow for upwelling of the Peruvian current, which is colder.

SOUTHERN OSCILLATION INDEX (SOI)

MADDEN JULIAN OSCILLATION FORECAST (MJO)

CHI 200 MB VERTICAL VELOCITIES FORECAST

Elsewhere, Tropical Storm formation is not expected during the next 7-10 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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