Scientific Forecaster Discussion
000 FXUS62 KJAX 110124 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 824 PM EST Tue Dec 10 2019 .NEAR TERM [Through Tonight]...Cold front just nw of area will move across se Ga this evening and across ne Fl after midnight. Low clouds and patchy fog off the Gulf will spread ne across mainly ne Fl ahead of the cold front. Scattered showers will accompany the frontal passage. The front will be south of the area by morning with lows in the mid 50s over se Ga and upper 50s/lower 60s across ne Fl. .AVIATION...[Through 00Z Thursday] Current VFR conditions will lower to IFR-LIFR as low cigs and vsbys move in ahead of approaching cold front. Behind the front winds will shift to the nw between 06z-10z and increase Wednesday morning. Gradual improvement to MVFR conditions expected Wednesday morning. && .PREV DISCUSSION [409 PM EST]... .SHORT TERM [Wednesday Through Friday]... Front will push south of the region Wednesday with little chance of any precip in the morning, as most of the energy from shortwave is not located close to the CWA. Still likely to see overrunning clouds Wednesday with some sprinkles possible as what's left from shortwave trough passes through the area. Temps will be much cooler than today's upper 70s and lower 80s, with highs only upper 50s to around 60 over the northwest zones, mid 60s around I-10 area, and lower 70s possible over the far srn zones. Breezy north-northeast winds mainly around coastal counties near 20 mph and gusty. Wed night, sfc high pressure pushes east to be due north of the area bringing sfc flow to the northeast, with the cold front slowing down as it pushes southward down the FL peninsula. Northeast flow may bring some chance for a few showers for the southeast zones, with breezy flow continuing for coastal counties up to 20-25 mph at times. Lows are colder as coolest air arrives with lows in the 40s and 50s, coldest over interior southeast GA. Thursday, more changes occurring as the front stays to our south, and another shortwave moves into the south central U.S. helping to enhance lift and cloudiness across the northern Gulf, and north FL and srn GA. Winds will be continuing out of the northeast with chance of showers expected. Breezy north-northeast winds expected again near 20 mph. Rain chances ramp up late Thursday-Thursday night and Friday as the shortwave moves through the lower MS valley and the southeast states and induces sfc low cyclogenesis over the northern Gulf of Mexico. The low will push northeast and will be north of the area late Friday night. Ahead the low pressure, warm front is likely to push into northeast FL which should enhance rainfall chances. A few strong storms possible Friday afternoon and evening as the low passes through the region and low level winds increase. .LONG TERM [Saturday Through Tuesday]... Sfc low pressure will likely be north of the area with a trailing cold front to push south of the area Saturday, and weak high pressure will gradually build into the area Saturday night through Sunday. Gradual clearing skies Saturday through Sunday with near seasonable temperatures. Weak high pressure moves east of the area Monday and resultant warm front will push northward through the area Monday. Temps warm Monday to above normal. A cold front is forecast to approach the area Monday night with a chance of precip again Tuesday as the front makes its way into the deep south, with frontal passage either as early as early Tuesday morning or Tuesday night, given the timing disagreement between GFS and ECMWF. .AVIATION... [Through 18Z Wednesday] VFR conditions will prevail through the remaining daylight hours, but another round of IFR-LIFR cigs and vsbys is anticipated late tonight/early Wed morning ahead of an approaching cold front. Behind the front Wed morning, winds will pick up from the northwest, blowing out low vsbys, but those low cigs may be stubborn to lift even at the end of the TAF cycle. .MARINE... South to southwest flow continues into this evening ahead of an approaching cold front. The cold front is forecast to push into the GA waters around 06z and then into northeast FL waters 06-12z Wed. Cold front should be south of the waters 15z Wed. Small Craft Advisory conditions (20-33 kt and seas 7 ft) will be possible starting around as 14z-18z. Some gale force wind gusts are likely and due to lower confidence on gale warning have elected to have SCA at this time. Pressure gradient remains pinched Wed night through Thu night between the front to our south, which becomes stalled over srn FL, and high pressure ridge to our north. Pressure gradient becomes loose Friday as trough develops offshore of northeast FL and wedge of high pressure gives way to a developing low pressure system moving through the northeast Gulf of Mexico. As the low tracks northeastward across the southeast late Friday night into Saturday, winds may shift around to the south, but forecast is highly dependent on the eventual track of the low. It does appear winds will come around the northwest sometime on Saturday as the low pressure moves away and trailing cold front from the sfc low moves through the area. Weak high pressure builds into Sat night to Sun likely resulting in winds and seas on the low side. Rip Currents: Moderate risk of rip currents at northeast Florida and southeast Georgia beaches rest of today and possible high risk of rip currents on Wednesday. Coastal impacts: We will see elevated water levels Wed night through Thursday evening due to increased northeast flow (and higher surf) and the astronomical full moon phase Thu, Dec 12th. Model extratropical surge fcst suggesting about 1 foot, and for now no coastal advy is anticipated but will be monitored. .HYDROLOGY... At this time, rainfall forecast amounts with the stronger system Thursday night into Friday night week range from a low of only 0.5 inches over coastal northeast FL to 1.5 inches over parts of southeast GA. && .PRELIMINARY POINT TEMPS/POPS... AMG 53 62 44 60 49 / 30 10 10 20 60 SSI 56 63 50 62 56 / 30 10 10 30 60 JAX 59 68 52 65 58 / 30 10 10 40 60 SGJ 62 69 56 69 61 / 40 20 20 40 50 GNV 61 71 54 68 59 / 30 10 10 20 40 OCF 62 75 55 72 60 / 30 20 10 20 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...Small Craft Advisory from 10 AM Wednesday to 9 AM EST Friday for Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-Waters from Fernandina Beach to St. Augustine FL from 20 to 60 NM-Waters from St. Augustine to Flagler Beach FL from 20 to 60 NM. Small Craft Advisory from noon Wednesday to 5 AM EST Friday for Coastal waters from Altamaha Sound to Fernandina Beach FL out 20 NM-Coastal waters from Fernandina Beach to St.