SUB-TROPICAL STORM ANDREA FORECAST SYNOPSIS…ISSUED MAY 20, 2019…8:45 P.M. EDT

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(T. F. “Storm” Walsh)

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Good evening everyone!,

As of early this evening, the NHC, based on information provided by an Air Force Hurricane Hunter aircraft, and satellite data, has upgraded INVEST 90L to Sub-tropical storm ANDREA.  The following information was available on ANDREA in the 6:30 p.m. advisory from the NHC:

6:30 PM AST Mon May 20
Location: 28.8°N 68.7°W
Moving: N at 14 mph
Min pressure: 1006 mb / 29.71 in
Max sustained: 40 mph

HURREVAC NHC TRACKING MAP

HURREVAC ANDREA 72 HOUR FORECAST WIND SWATH

RAMSDIS ANDREA FLOATER SATELLITE LOOP (CLICK IMAGE)

Based on satellite and aircraft fixes, and my analysis of the recent steering layers maps, ANDREA is moving toward the north.  I expect this motion to continue during the next 12 – 18 hours, before ANDREA before she begins to move toward the NE sometime on Tuesday, and then begins moving more eastward by Tuesday evening.  I am basing this on analysis of the current forecast steering layers maps, indicating a trof associated with an extratropical low, will begin to absorb ANDREA.  ANDREA will be moving between the subtropical ridge to her east, and ridging over the SEUS.  She will be moving through the weakness, which will allow her to be captured by the trof featured in forecast steering.  At this time, I concur with the NHC forecast track, based on the clustering of most of the model guidance through 72 hours.

18Z MODEL GUIDANCE FROM RAL  (ISSUED PRIOR TO ADVISORY)

Based on analysis of the wind shear forecast, and current upper level wind map, which indicates upper level winds to her north, are providing an outflow channel/jet, I concur with the NHC intensity forecast, as the upper riding is forecast to remain intact for the next 24 hours. 

UPPER LEVEL WIND MAP FROM CIMSS

The intensity model guidance right now, is not the best, although the SHIP and DSHIP modeling are the only 2 at the moment that have shown tropical storm status.  The only problem I have at the moment with these two models, is that they continue to show strengthening.  This is not the case however, as by Wed., the semi-favorable upper pattern collapses, as ANDREA becomes absorbed.  Once this occurs, weakening should be in order.  It is also noted that ANDREA is now located over 25C SST’s.  Based on these factors, I believe the NHC intensity forecast to be correct.

SST MAP FROM CIMSS

NHC INTENSITY FORECAST
INIT 20/2230Z 28.8N 68.7W 35 KT 40 MPH

12H 21/0600Z 30.2N 68.9W 40 KT 45 MPH
24H 21/1800Z 31.1N 68.3W 35 KT 40 MPH
36H 22/0600Z 31.5N 66.4W 30 KT 35 MPH
48H 22/1800Z…DISSIPATED

ECMWF SHEAR FORECAST


There have been no watches or warnings issued for Bermuda, and based on the current forecast, I do not expect any to be issued, unless for some unknown reason, forecast conditions change.

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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