000 AXNT20 KNHC 140005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 725 PM Wed May 13 2020 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough axis passes through the coastal sections of Guinea near 11N15W and reaches to 06N20W, where scatterometer data from this afternoon indicated that it transitions to the ITCZ and continues to 05N28W to 02N36W to 01N42W and to the coast of Brazil near 01S48W. Numerous moderate to strong convection is seen within 60-90 nm of the trough between 16W-21W. Scattered moderate to isolated strong convection is within 30 nm of the ITCZ between 24W-28W, and also north of the ITCZ within 30 nm of line from 05N30W to 03N36W. Similar activity is north of the ITCZ within 30 nm of 04N48W. GULF OF MEXICO... A mid-level shortwave tough extending from the north-central Gulf to the southeastern Gulf is moving eastward. At the surface, ridging extends across the region from a 1028 mb high centered off the U.S. Eastern Seaboard. A stationary front extends from east of the Bahamas to the Straits of Florida along a position from 24N80W to 24N85W. This is presently acting serving as the focus for scattered showers and thunderstorms to persist across the Straits of Florida as well as along and inland northwestern Cuba and the over the southeastern Gulf waters to the south of 25N and east of 86W. Similar activity is noted over the northern Gulf waters from 27N to 29N and between 90W-94W. With the mid- level shortwave trough advancing eastward toward Florida through the next couple of days or so, expect for the scattered shower and thunderstorm activity to increase in coverage, while it lifts northward across southern Florida and the adjacent Gulf waters. Both buoy observations and the latest Ascat data indicate moderate to fresh east to southeast winds across just about the entire area, with the exception of the southeastern Gulf, where a tighter gradient in place there along with wind gusts from the aforementioned shower and thunderstorm activity is producing strong east winds across those waters and peak wave heights of up to 8 ft. Elsewhere, wave heights are in the range of 4-7 ft except in the extreme NW Gulf where lower wave heights of 2-4 ft are observed. As for the forecast, the stationary front will weaken through late tonight and dissipate by late Thu afternoon. The tight gradient in place over the southeastern Gulf and over southern Florida will maintain little change with winds over those water through Thu night. Elsewhere, the moderate to fresh east to southeast winds will continue through the upcoming weekend. A weak cold front may approach the northern Gulf late on Mon night. CARIBBEAN SEA... Mid-level ridging, with an axis stretching roughly from the Honduras/Nicaragua northeastward to Puerto Rico, is providing for light to moderate subsidence and associated drier air over the western and central sections. Upper-level riding is over the far eastern Caribbean. Its axis is identified to be along 63W, and stretches north-northeastward well north of the Sea to the central Atlantic. Strong subsidence and dry sinking air accompanies this ridge from along the coast of Venezuela northward to 17N and east of 69W. Only a few low cloud streamers, with possible isolated showers are seen east of 69W. Afternoon scattered shower and thunderstorm fired up over the interior of the western part of the Dominican Republic and in some interior sections of Cuba. With gradual loss of day time heating, this activity appears to be weakening. Small patches of low clouds moving west-northwestward with isolated showers are seen from 15N-18N and between 72W-76W. Moderate to fresh trade winds are over the eastern and central Caribbean, while gentle to moderate trade winds are over the western Caribbean and fresh to strong trade winds over the south- central Caribbean waters. Wave heights are in the 3-6 ft range, with higher wave heights, up to 7-8 ft, offshore the northwest coast of Colombia. As for the forecast, a relatively weak pressure gradient will strengthen later this week as high pressure builds north of the area. The fresh to strong trade wind will change little over the south- central Caribbean through the upcoming weekend. Northerly swell over the Tropical N Atlantic waters south of 15N will subside into Thu. Fresh winds will pulse over the Gulf of Honduras from Thu night into early next week. ATLANTIC OCEAN... Westerly upper-level flow is over the western half of the area, with an embedded sub-tropical jet stream branch that extends from South Florida northeastward across the NW Bahamas and eastward to near 26N61W. Another jet stream branch extends from 26N61W northeastward to north of 32N57W. A narrow mid to upper- level trough is along a position from near 26N46W to an elongated mid to upper-level low lifting northward at 18N52W and from the low it extends south-southwest to near 08N56W. Moderate to strong subsidence is within 240 nm west and 60 nm east of the low and trough. A highly amplified mid and upper-level ridge, with a crest north to near 24N41W, is to the east of these features to 25W. East of 25W, broad mid to upper-level troughing is the main feature over this section of the area. At the surface, a cold front enters the area at 32N56W and continues southwestward to 29N62W, where it becomes stationary to 25N69W and west-southwest to the Bahama Islands near 23N76W and to the Straits of Florida at 24N81W and to 24N83W. A pre- frontal trough extends from 28N59W to 22N68W. Scattered to numerous showers along with isolated thunderstorms cover the waters south of 27N and west of about 71W. A more concentrated area of scattered showers and thunderstorms is along and within 120 nm north-northeast of the Cuban coast from 74W to 79W. In addition to the nearby frontal boundary and jet stream energy aloft in play, the occurrence of moist fresh to strong northeasterly winds converging along the Cuban coast will continue to sustain this activity through possibly Fri. Isolated showers and thunderstorms are possible between the front and the trough. Another trough is analyzed from 27N55W to 21N58W. Broken low and mid-level clouds with isolated showers are seen from 21N to 27N and between 54W-58W. Strong high pressure ridges southward over the western Atlantic waters north of the stationary front. The resultant tight gradient is allowing for fresh to strong east winds and wave heights peaking to 8 ft over these waters. In the eastern Atlantic, a cold front supported by the broad mid to upper-level trough mentioned above, recently passed the Canary Islands. It extends from near 32N10W to 27N16W to 26N66W and northwestward to 30N35W. Isolated showers are possible along this front. Otherwise, high pressure, anchored by a 1026 mb high center just north of the area at 33N32W, covers this part of the area. Light to moderate winds are noted throughout the central and eastern Atlantic with wave heights in the 4-7 ft range. As for the forecast, the stationary front will will weaken through late tonight and dissipate by late Thu afternoon. The strong high pressure over the western waters will continue through Fri, maintaining the tight gradient and fresh to strong east winds and wave heights to 8 ft there. An area of low pressure is expected to form near or just north of the Bahamas in a couple of days, and potentially develop into a subtropical depression or storm this weekend while moving to the northeast over the western Atlantic. $$ Aguirre