000 AXNT20 KNHC 201107 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 706 AM EDT Mon Apr 20 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 0600 UTC surface analysis and satellite imagery through 1045 UTC. ...SPECIAL FEATURES... Atlantic Gale Warning: A cold front will enter the waters east of northern Florida this afternoon, then cross the waters N of 22N through Wed evening. Fresh to strong southerly winds will precede this front north of 27N beginning early this morning and increase to gale force in deep convection north of 29N by mid to late morning today. The gale force winds are forecast to lift north of the area by this evening. Then winds in the vicinity of the front will diminish to fresh to strong speeds as the front shifts E. Seas of 9 to 12 ft can be expected in the gale force wind area north of 29N between 70W-80W late this morning into this evening. Please see the High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC or at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends southwestward from the coast of Sierra Leone on the coast of Africa near 07N12W to 01N22W, where overnight scatterometer data indicates that it transitions to the ITCZ and continues to 02N35W and to 01N50W. Scattered moderate to isolated convection is within 120 nm northwest of the trough between 12W-14W, within 60 nm northwest of the trough axis between 15W-18W and within 60 nm south of the ITCZ between 24W- 28W. Scattered moderate convection is within 180 nm north of the ITCZ between 23W-27W, and also north of the ITCZ within 30 nm of a line from 03N30W to 04N33W and to 05N36W. An area of scattered moderate to strong convection is observed from 01N to 07N and west of 49W to the coast of Brazil. GULF OF MEXICO... As of 09Z, a cold front has pushed southward into the northern Gulf waters. It is analyzed along a position from Cape San Blas in the Florida panhandle to just south of the Mississippi Delta and west-northwest from there to just east of Galveston, Texas. A rather potent squall line racing southeastward is out ahead of the front from Apalachee Bay to near 28N87W, while a rather vigorous mid-level shortwave trough advances eastward over the western Florida panhandle. This along with plenty atmospheric instability in place along with a strong low-level jet has lead to the overnight development of strong to severe thunderstorms along and within 60 nm southeast of the squall line. This activity is capable of producing strong and damaging winds as well as frequent lightning strikes and very rough seas as it races southeastward during the morning hours today. Otherwise, a surface ridge extends from western Cuba to the central Gulf of Mexico. Overnight Ascat data indicates fresh to locally strong southwest winds over the north- central Gulf, with fresh southeast winds farther south near the Yucatan Peninsula. Gentle winds are present over the western Gulf. The forecast calls for the aforementioned cold front to reach the east-central Gulf this afternoon while weakening, with fresh to strong southerly winds ahead of it diminishing to mainly fresh speeds. Scattered showers and thunderstorms with the preceding squall line will continue southeastward to the east- central Gulf this morning. The next cold front is forecast to approach the NW Gulf Wed night into Thu morning. Fresh to strong winds are forecast to develop ahead of the front over the western half of the Gulf by Tue night. The front will reach from near Cross City, Florida to 28N90W by Fri morning. Otherwise, smoke from agricultural fires in southern Mexico could reduce visibility in the SW Gulf. CARIBBEAN SEA... Mid to upper-level ridging and associated strong subsidence will maintain dry and stable weather conditions across the majority of the basin for the next few days. There are presently two exceptions. The first is in the eastern Caribbean, including the vicinity of Puerto Rico and the Leeward Islands, where patches of low-level moisture in the form of mainly broken low clouds are noted moving quickly westward in the trade wind flow. Scattered shower activity is present with some of this moisture. The other exception is in the northwest Caribbean, where isolated showers are seen between the northeast coast of Honduras to just south of Jamaica and to east-central Cuban coast. Overnight Ascat data shows fresh trade winds in the central Caribbean, except locally strong near the coast of Colombia. Fresh wind speeds are also present from the Yucatan Channel to the coast of Honduras, with strong east winds within 60 nm of the north coast of Honduras. Moderate trade winds are present elsewhere. The forecast calls for high pressure north of the area to maintain fresh to strong winds in the south-central Caribbean and the Gulf of Honduras through Fri night. Mainly moderate to fresh winds are expected elsewhere during the entire period. Otherwise, smoke from agricultural fires in Central America could reduce visibility near the Yucatan Peninsula and offshore of Belize and Honduras. ATLANTIC OCEAN... A warm front extends southeastward from a 1004 mb low near Cape Hatteras, North Carolina to Wilmington where it transitions to a warm front that stretches southwestward to the Georgia/Florida border and northwestward from there to a 1008 mb low over west- central Alabama. Very active strong to severe shower and thunderstorm activity occurring over most of the southeastern U.S. has moved offshore the coast from just north of northeastern FLorida to the southern section of South Carolina. Similar activity, of scattered moderate to isolated strong intensity, has moved farther offshore, and is noted from along the coast from 30N to 33N, east to near 69W. This activity is under an area of upper-level diffluence that is helping to sustain it. As the mid-level shortwave trough, that is currently over the western Florida panhandle, continues eastward along with a cold front, it will act to push the shower and thunderstorms activity to east and northeast of the southeastern U.S. coast during this afternoon. Overnight Ascat data passes depict fresh to locally strong southerly winds north of 29.5N between 72W-77W. Strong to gale force winds are seen north of 30.5N in the same area. The 06Z synoptic analysis has a cold front extending from near 32N49W southwestward to 28N56W and to 26N65W, where it transitions to a warm front northwestward from there to north of the area at 32N72W. Broken to overcast low and mid-level clouds along with isolated showers and thunderstorms are noted within 120 nm east of the cold front north of 29N. Broken low clouds with isolated showers are along and within 120 nm southeast and south of the cold front from 27N to 29N. Farther east, another cold front with no significant convection or wind is along a position from 32N20W to 29.5N31W where it becomes stationary to 32N56W and a warm front northwestward from there to a triple point well north of the area. A 1026 mb high center is analyzed well north of the area near 35N30W and a 1019 mb high center is analyzed near 31.5N63W. Ridging associated to both of these features is maintaining gentle to moderate east winds over much of the Atlantic from 15N-28N and between 35W and the Bahamas. For the forecast west of 65W, the western segment of the cold front extending from 32N49W to 28N56W and to 26N65W will pull away from 65W during this morning as the warm front lifts north of the area. A second cold front, as mentioned in the first paragraph, will move over the waters east of northern Florida this afternoon, and a Gale Warning is in effect for the waters north of 29N and between 70W-80W as southerly winds ahead of this front significantly increase in response to a very strong low- level jet that will shift from the Gulf of Mexico to east of northern Florida and the southeastern U.S. See the Special Features section above for details. Another cold front will move across the SE U.S. on Thu with strong to possibly near gale force southerly winds developing ahead of the front over the waters east of northern Florida. $$ Aguirre