Highlight: MJO induces heavy rain FLA, severe WX northern U.S. and Mid-South to Mid-Atlantic warmth. Tropical low emerging eastern Gulf of Mex.
Discussion: Amplified signal strength of the Madden Julian oscillation (MJO) causing anomalous tropical convection from the far eastern East Pacific into the Atlantic equatorial region brings substantial influence to U.S. weather the next 7-10 days. The prevailing upper flow across the eastern U.S. invites tropical/subtropical moisture to gather in Florida causing soaking rains and enhance a stalled frontal boundary across the northern U.S. inducing frequent thunderstorms and heavy rain for the next week (or more). The release of heat from the convection causes areas in-between to turn quite warm at times Mid-South U.S. to the Mid-Atlantic States.
ECMWF indicates a surface low pressure area forming southwest of Tampa before sunrise tomorrow. The low pressure area drifts north into the northeast Gulf of Mexico tomorrow night. Presence of this subtropical low enhances Florida rainfall tomorrow. By Tuesday morning the low pressure area is into the Florida Panhandle but stays close to shore and may move west and southwest back over the northern Gulf of Mexico later late Tuesday/Tuesday night.
This system is subtropical in nature tomorrow meaning attached to an upper level cold trough. However, this system may become more tropical in nature is shifting offshore again Tuesday.
Gulf of Mexico SST are not currently quite warm enough to cause/sustain a tropical cyclone. Please note that NOAA/NHC is indicating a 30-40% chance of a tropical cyclone.
Fig. 1: NCEP MJO 14-day forecast and annotated implications.
Fig. 2: Satellite view of MJO convection in the tropics. Upper low over the eastern Gulf of Mexico is inviting that moisture northward to soak Florida.
Fig. 3: NOAA/WPC 7-day rainfall forecast identifies MJO-induced soaking rains in Florida and the enhancement of rainfall along northern U.S. frontal boundary.
Fig. 4: Convection across Florida releases heat pole ward dynamically forced warmer south of a persistent northern U.S. cold front days 1-5 ahead.
Fig. 5: Lingering warmth Mid-South to Mid-Atlantic in-between subtropical rains in the Southeast U.S. and frontal boundary across the northern U.S.