DISTURBANCE INVEST 90L FORECAST SYNOPSIS…ISSUED MAY 19, 2019…6:40 P.M. EDT

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(T. F. “Storm” Walsh)

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Greetings everyone!,

The area of disturbed weather I have been monitoring SW of Bermuda, has been designated INVEST 90L by the NHC.  Based on the 18Z ATCF BTK information, the following was available on INVEST 90L:
LOCATION: 25.8N;65.9W
MIN. CENTRAL PRESSURE : 1015mb / 29.97in

CARIBBEAN SATELLITE LOOP (CLICK IMAGE)

I have not included forward motion on this area, as guidance indicated a motion of 265 degrees, or just south of west, which disagrees with the current lower steering layer.

CURRENT STEERING MAP

The NHC has kept the probability of development at a MEDIUM (40%) probability during the next 5 days.

NHC GRAPHICAL 5 DAY TWO

I really have no change at this time to my previous forecast thinking, which pretty much follows the latest NHC Special Tropical Weather Outlook (STWO).

Based on my analysis this afternoon and evening, the global models are still in good agreement of a surface low developing either late tomorrow, or very early on Tuesday.

ECMWF

GFS

CMC

Currently, upper level winds are still not favorable for development at this time.  However, the current shear tendency indicates wind shear still continues to weaken, and the streamlines, as well as the current upper level wind analysis indicates the upper level ridge I had mentioned in my previous forecasts, may be in the process of developing.  You’ll note the red lines I put in the upper level map, indicating the flow, which is now producing a minimal outflow jet to the north of the INVEST.  Divergence has increased aloft as well since yesterdays synopsis.  Based on analysis of relative humidity forecast maps, and forecast development of the upper level ridge, more favorable conditions are forecast, and a surface low could develop late tomorrow, or very early on Tues., as depicted by the global modeling.

CIMSS UPPER LEVEL WIND MAP

UPPER LEVEL DIVERGENCE

Based on the forecast wind field analysis of the possible low, development of a sub-tropical system appears to be the order.  The intensity forecast remains tricky and of low confidence, as model guidance has just started this afternoon, and the models have no closed circulation to “focus” on at this time.  Given my best estimate, based on analysis of the 18Z intensity model guidance, if development does occur, the low may have the potential to become a sub-tropical depression.  By Wed., upper level winds begin to become unfavorable, due to interaction with the extra-tropical low, and loss of the brief upper level ridge.

GFS 60 HOUR WIND SHEAR FORECAST

18Z EARLY INTENSITY GUIDANCE (LINKED)

Analysis of forecast steering maps, global modeling and ensemble plots, INVEST 90L should begin moving more to the north within the next 24 hours, then begin a turn more to the NNE.  As the system approaches very close to, or possibly over Bermuda very late Tues., or early Wed., the system will be absorbed by an extra-tropical low and should be swept eastward to ENE. The turn to the N and NNE mentioned above will be due to a weakness between ridging over the SEUS and the central Atlantic in about 24 – 30 hours from 12Z this morning.  Of course, subject to change, depending on where, when the low develops, and how developed the low center becomes.  This should be a fairly breif system, seeing it is forecast to become absorbed over the next 60 – 72 hours.

ECMWF EPS

NCEP GEFS

CMC GEPS

I will continue to monitor the area for the development, and for any significant changes, should they occur.  I will update again when warranted. 

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

You may direct any questions this season by contacting me personally, ANYTIME, at: twalsh22000@yahoo.com

Have a blessed and safe week!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS

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