000 AGXX40 KNHC 260759 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 359 AM EDT Sun Mar 26 2017 Marine Weather Discussion for the Gulf of Mexico, Caribbean Sea, and Tropical North Atlantic from 07N to 19N between 55W and 64W and the Southwest North Atlantic including the Bahamas ...GULF OF MEXICO... High pressure extending from western Atlantic across the gulf to 92W will weaken during the upcoming week. A squall line is advancing rapidly to the east from just west of Panama City Florida southwest to near 28N88W. Scattered to numerous thunderstorms along the squall exhibited frequent lightning strikes during the past several hours, however the lightning detection display on satellite imagery is presently indicating that the lightning is diminishing. The thunderstorm activity is still capable of producing strong bursts of wind gusts as well as cloud to water lightning strikes as it makes headway across the northern part of zone GMZ015 during the morning. Currently, gentle to moderate southeast to south flow is observed, with the exception of the waters near the Yucatan Peninsula where northeast to east moderate to fresh flow is found. Observed sea state is of the 3-5 ft range throughout, except for lower seas of 2-3 ft in the far northeast and east portions and small pockets of 5-6 ft seas in the eastern section south of 26N. Southeast wind flow will increase to fresh to strong category on Tuesday over the western portion of the gulf, and spread eastward to cover much of the central gulf on Wednesday as a weak cold front approaches the Texas coast. The front is forecast to move over the far western gulf on Thursday, with the fresh to strong southerly winds shifting to the central waters. The typical climotological thermal trough will move westward across the Bay of Campeche each night and dissipate by late morning. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... The pressure pattern across the Caribbean continues to weaken as broad low pressure northeast of Hispaniola lifts northward. The pressure pattern will remain weak through Tuesday as the low pressure pulls further away from the Caribbean and weak high pressure settles over the Bahamas. This will support mainly moderate trades across the Caribbean through Tuesday night. High pressure ridging associated with the high over the Bahamas will build southward over the northwest and north-central Caribbean zones beginning Tuesday night. This should allow for fresh to locally strong easterly winds to materialize over the Gulf of Honduras and zone AMZ011 from early Wednesday through Thursday. Strong east to southeast winds will become confined to the Gulf of Honduras late Wednesday night through Thursday. A trough currently extending south from the low pressure northeast of Hispaniola to 15N70W will become diffuse by this afternoon. Scattered showers and thunderstorms that yesterday were occurring over much of the eastern Caribbean have decreased, with only isolated shower/thunderstorm activity noted over the open waters east of 70W. Scattered showers and thunderstorms are primarily located in the vicinity of Puerto Rico, the Mona Passage and the Leeward Islands. Overall, this activity is expected to decrease by late Monday afternoon at which time the remaining activity should be mainly over and near the Leeward Islands. For the tropical Atlantic zones, north swell of 8-9 ft seas is propagating through zones AMZ127 and AMZ027. Wave model guidance indicates that this swell will decay today. Seas lower to below 8 ft this evening in the northern part of zone AMZ127. Another batch of long period northerly swell will propagate into the eastern section of zone AMZ127 on Wednesday or Wednesday night, and produce seas of 7-10 ft. The swell will be short-lived as it will exit east-southeast away from the zone on Thursday. ...SW N ATLANTIC INCLUDING THE BAHAMAS... Both satellite imagery and an Ascat pass from 0204Z confirm the position of the low pressure that develop yesterday just northeast of the eastern tip of the Dominican Republic to be near 21N68W. A trough extends from the low southward through the Mona Passage and to the Caribbean Sea near 15N70W. Another trough extends from the low northeastward to near 25N63W. The same Ascat pass highlighted a large swath of 30 to 35 kt gale force east winds from 22N to 27N between 64W and 69W, and to the southeast of the low from 20N to 22N between 63W and 66W. An extensive area of 20-30 kt east winds are noted elsewhere south of 29N east of 70W. The aforementioned winds are supported by a very tight pressure gradient between the low pressure and strong high pressure entrenched over the basin to north and northwest of the low. It is estimated that the gale winds developed in the late afternoon hours to very near evening time. Recent altimeter data along with buoy observations reveal seas up to the 14 ft east of the Bahamas near 24N69W, and seas of 8-12 ft elsewhere south of 29N east of the Bahamas. Waveheights were adjusted with guidance from the TAFB NWPS output to account for these observed waveheight values. The low is forecast to track northward across zones AMZ125 and AMZ121 through tonight, then turn northeastward late tonight into Monday as it tracks over the northern portion of zone AMZ121, and continue northeastward across the southeast portion of zone AMZ115 by Monday afternoon and east-northeast to just east of the southern portion of the same zone by late Monday night. The associated winds and long duration of the winds will build seas up to around 18 ft to the north of the low, with 8-12 ft swell across the majority of the SW N Atlantic waters outside of the Bahamas through Monday. The highest of the seas are expected to be confined over the northeast zones Monday night through Wednesday. There is still uncertainty with respect to the actual intensity of the low as tracks across much of the eastern zones during the next few days. Of importance here with regards to the low pressure system is that marine hazardous conditions will be found well to the north and northeast of the low. These conditions are already underway, and will deteriorate further as we go the into the early part of the upcoming week. Model prog weak high pressure to settle in over the Bahamas as the low exits the basin bringing rather tranquil weather conditions. Seas subside to less than 8 ft in the eastern portions of zones AMZ121 and AMZ115 late Wednesday night into early Thursday. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... .AMZ115...ATLANTIC FROM 27N TO 31N BETWEEN 65W AND 70W... Gale Warning Today into Mon. Gale Conditions Possible Mon night into Tue. .AMZ121...ATLANTIC FROM 22N TO 27N BETWEEN 65W AND 70W... Gale Warning tonight into Sun night. $$ *For detailed zone descriptions, please visit: http://www.nhc.noaa.gov/abouttafbprod.shtml#OWF Note: gridded marine forecasts are available in the National Digital Forecast Database (NDFD) at: http://www.nhc.noaa.gov/marine/grids.php For additional information, please visit: http://www.nhc.noaa.gov/marine $$ .Forecaster Aguirre. National Hurricane Center.