Tropical storm WARNING for Fl. Panhandle & Big Bend...WATCH for Cental Fl. west coast...Tropical storm "Debby" edging north/northeast...heavy rain for the First Coast....
** Potentially significant flooding threat for the First Coast...isolated tornadoes late tonight & especially Monday, possibly continuing into at least Tue. depending on exact track **....
"Debby" continues to suffer from southerly shear & mid & upper level dry air to its west (see 2nd satellite [water vapor] image below) causing a lopsided tropical cyclone heavily weighted on the east side. Hurricane hunter aircraft found a widening wind field to the north & east which has caused the NHC to issue tropical storm warnings for the Fl. Panhandle. As I mentioned last week, this may end up being classic early season development on the west end of a trough where development is almost painstakingly slow but once established, the tropical cyclone pretty quickly organizes in the long run then would have the chance to intensify. So this bears a great deal of scrutiny the next few days especially as the upper low weakens & peels away to the west & south & loses some of its influence on the tropical low.
As for the track....a good deal of uncertainty continues. The European remains the farthest west but has shifted north bringing the storm to the Central or Eastern Gulf Coast by Tue./Wed. Several other models has similarly shifted north. The GFS remains the opposite but has slowed considerably & has now been joined by the Canadian model. So from a timing standpoint, the models have come into better agreement but remain far apart on track.
The GFS still takes the storm across Central or N. Florida but not until midweek. The ultimate track will continue to hinge on the strength & depth of an upper level trough in the Eastern U.S. and
an upper level ridge across the Southern U.S. For the First Coast
...heavy rain & a few t'storms will occur through at least Monday with the potential for several inches of rain, especially across NE Fl. into S. Central Ga. If the westward move is accurate then any other significant impacts from the storm would stay well west of Jacksonville. If the eastward track -- or if the storm remains stationary for extended time -- then a significant flooding threat will develop along with at least isolated tornadoes.
Given the weakening upper low in the NW Gulf & only the slow strengthening of the upper ridge, I personally favor the slower move northward then holding stationary then a move west/northwest as the ridge to the north strengthens. But the move east is by no means completely off the table, so the ultimate track remains unusually tricky to forecast at this point.