073 FXUS62 KJAX 100915 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 515 AM EDT Wed Oct 10 2018 ...TORNADO THREAT INCREASES THIS AFTERNOON AS MAJOR HURRICANE MICHAEL MAKES LANDFALL ALONG THE FLORIDA PANHANDLE COAST... ... ...FLASH FLOOD WATCH ISSUED FOR PORTIONS OF INLAND SOUTHEAST GEORGIA... .Currently... Early morning surface analysis depicts Category 4 Hurricane Michael centered about 140 miles to the southwest of Panama City, FL. Weakening Atlantic high pressure (1024 millibars) was centered near Bermuda, with its axis extending westward into the southeastern U.S. Meanwhile, a cold front was progressing eastward across the mid and lower Mississippi Valleys. Aloft...a highly amplified pattern prevails as deep layered ridging remains centered off the U.S. eastern seaboard and deep troughing prevails over the western half of the nation. Gusty showers associated with a deep southeasterly flow have migrated north of the Altamaha River, with subsidence on the periphery of Michael's circulation resulting in little to no shower activity throughout southeast Georgia, northeast and north central Florida during the overnight hours. Michael's outer rain bands are moving onshore along the southwest and west central Florida coasts as well as the Big Bend and panhandle coasts as of 09Z. The subsident and unseasonably humid airmass over our region has resulted in low stratus formation over inland southeast Georgia, with high cirrus clouds on the periphery of Michael's circulation otherwise blanketing our region. Unseasonably warm conditions prevail as breezy southeasterly winds are already in place over coastal southeast Georgia, northeast and north central Florida, where temperatures are holding steady in the upper 70s to lower 80s. Lighter east- southeast winds are in place over inland southeast Georgia, where temperatures and dewpoints were in the mid to upper 70s. .Near Term /Today through Thursday/... Major Hurricane Michael will make landfall along the Florida panhandle coast early this afternoon, likely at Category 4 intensity, which is an unprecedented event for the month of October in that area. Latest short-term, high resolution guidance indicates that outer rain bands associated with Michael will move north-northeastward and will enter the western portions of north central Florida and the western Suwannee Valley during the late morning hours today. Another rain band may develop near the Altamaha River over eastern sections of southeast Georgia late this morning. Latest 06Z model guidance depicts an environment that will be increasingly favorable for supercells and tornadoes this afternoon as Michael's outer rain bands begin to overspread our region from southwest to northeast. Mixed Layer CAPE values of 1000-1500 j/kg will be in place across north central Florida, the Suwannee Valley and inland southeast Georgia by late this afternoon as Storm Relative Helicity values increase to 400-600. Much of our region will likely be placed in a Tornado Watch later this morning through tonight given these variables. Breezy conditions will prevail in advance of the arrival of Michael's outer rain bands, and filtered sunshine this morning will boost highs into the mid to upper 80s by early afternoon. Heavy downpours will overspread inland southeast Georgia as the afternoon progresses, with the heaviest rainfall occurring this evening and tonight as Michael accelerates north-northeastward across southwest and south central Georgia. The potential exists for widespread 3-5 inch amounts tonight for locations northwest of Waycross, where a Flash Flood Watch has been issued. The tornado and sustained wind threats will also be maximized early this evening as Michael makes it closest approach to our western Georgia counties. Several outer rain bands will likely rotate northeastward through our region, with the highest helicity values generally remaining west of the U.S. Highway 301 corridor. Sustained tropical storm force winds will be possible this evening across the western Suwannee Valley, generally east of Lake City, and for locations west of Waycross throughout the overnight hours. Winds will quickly veer to southerly this evening and will remain breezy elsewhere, shifting to south-southwesterly during the predawn hours. Heavy rainfall should begin to exit inland southeast Georgia from southwest to northeast towards sunrise as Michael turns northeastward towards the Savannah River Valley. Breezy southerly winds will keep lows in the upper 70s to around 80. Winds will shift to westerly early on Thursday as Michael continues to accelerate northeastward through the Carolinas. Lingering outer rain bands along the Altamaha/Ocmulgee Rivers will diminish as the morning progresses, with skies clearing from west to east during the afternoon. A much drier air mass will filter into inland southeast Georgia. and some slight cool air advection will develop during the afternoon hours as winds become west-northwesterly, which will keep highs in the upper 80s. Meanwhile, breezy westerly winds, and increasingly dry and subsident air mass and mostly sunny skies will boost highs to near daily record values for October 11th, with low and even mid 90s possible for much of northeast and north central Florida. These unseasonably hot temperatures will extend all the way to the coast, where maximum heat index values around 100 degrees are expected throughout the afternoon hours. .Short Term /Thursday Night thru Friday Night/... Thu Night...Clearing skies in the wake of Michael as it tracks through the Carolinas and drier NW flow develops across the region. Temps will actually be able to fall into the 60s for most areas by Fri Morning except some lingering lower 70s along the Atlc Coast and St Johns River basin. Friday...Mostly Sunny and a bit cooler day than Thursday in the drier NW flow with Max Temps in the lower 80s across SE GA and middle to upper 80s across NE FL. Fri Night...Mainly clear skies continue as High Pressure begins to rebuild N and NW of the region with mainly light north winds and the drier airmass will allow for low temps to fall into the mid- upper 50s inland for the first time this fall and in the 60s along the coast. .Long Term /Saturday-Tuesday/... Saturday...High pressure builds into the Carolinas and winds become NE once again but airmass still too dry to support any coastal showers and Max Temps continue in the 80s. Sunday...Onshore flow increases slightly with steering flow out of the south just off the surface but Pops still generally just below 20% with just a few coastal showers expected. Temps warm to above normal levels in the mid to upper 80s, with a few near 90 readings over inland NE FL. Monday/Tuesday...Onshore flow and deeper moisture aloft along with above normal temps will help to trigger some scattered showers and isolated storms mainly during the daytime hours. Max Temps will continue well above normal with highs in the upper 80s/near 90 inland and middle 80s along the coast. && .Aviation... MVFR to IFR ceilings are expected this morning, and other than a few breaks between rainbands, MVFR to low end VFR conditions are expected through the period. Isolated showers are moving inland near the coastal terminals, and rainbands from Major Hurricane Michael will approach north central Florida throughout the morning and spread inland throughout the day. Winds will remain east- southeasterly at 12 to 20 knots, with gusts near 25-30 knots by mid-morning. Higher wind gusts can be expected with rainbands, and across the western third of the forecast area as Michael tracks inland tonight as winds shift south to southwesterly. Sustained 20 to 30 knot winds with higher gusts can be expected across southeast Georgia and the Suwannee Valley. && .Marine... Major Hurricane Michael is approaching the Florida panhandle coast and will make landfall early this afternoon. South-southeasterly winds will remain sustained in the 20-25 knot range today and will become increasingly gusty this afternoon as outer rain bands reach the coastal waters. These rain bands will increase in frequency early this evening and will be squally with waterspouts possible. Seas today will build to 6-9 feet, with occasional seas up to 14 feet possible well offshore by late afternoon. Tropical Storm Warnings remain posted for the southeast Georgia coastal waters through early Thursday afternoon, with Small Craft Advisories in place for the northeast Florida waters. The strongest winds over our waters will occur overnight through the early morning hours on Thursday, as sustained winds shift to southerly by this evening and strengthen to 25-30 knots with occasional gusts to around 40 knots. Higher winds will be possible within squalls embedded in the outer rain bands. Seas will peak in the 7-111 foot range overnight, with occasional seas up to 14 feet possible well offshore. Rain bands should depart the coastal waters during the morning hours on Thursday as Michael accelerates northeastward towards the Savannah River Valley, with offshore winds developing and gradually subsiding during the afternoon hours. Seas will fall back to Caution levels of 5-6 feet in the Georgia waters by Thursday night and 3-4 feet for the northeast Florida waters as Michael moves through eastern North Carolina. Offshore winds will prevail Thursday night and Friday and will turn northerly by Friday night as our local pressure gradient continues to loosen. High pressure will then build southeastward into the Ohio and Tennessee Valleys by Saturday, with onshore winds developing over our waters this weekend. Coastal Flooding/Rip Currents: A high risk of rip currents will continue through Thursday, with rough and dangerous surf conditions prevailing with breakers generally in the 5-7 foot range. Minor flooding will be possible during the morning high tide along the Atlantic coast and within the St. Johns River basin through this evening, mainly due to strong onshore winds combining with high astronomical tides created by the new moon cycle. && .PRELIMINARY POINT TEMPS/POPS... AMG 85 78 89 60 / 60 90 40 10 SSI 85 80 89 68 / 50 50 20 10 JAX 89 80 91 68 / 50 40 10 10 SGJ 89 81 92 73 / 40 30 10 10 GNV 88 79 90 68 / 50 60 10 10 OCF 88 79 90 69 / 70 60 20 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Tropical Storm Warning for Columbia-Gilchrist-Hamilton-Suwannee. High Rip Current Risk through late tonight for Coastal Duval- Coastal Flagler-Coastal Nassau-Coastal St. Johns. High Surf Advisory until 10 AM EDT Thursday for Coastal Duval- Coastal Flagler-Coastal Nassau-Coastal St. Johns. Coastal Flood Advisory until 6 AM EDT Thursday for Clay-Coastal Duval-Coastal Flagler-Coastal Nassau-Coastal St. Johns- Inland Duval-Inland St. Johns. GA...Tropical Storm Warning for Appling-Atkinson-Bacon-Brantley- Charlton-Clinch-Coastal Camden-Coastal Glynn-Coffee-Echols- Inland Camden-Inland Glynn-Jeff Davis-Pierce-Ware-Wayne. Coastal Flood Warning until 6 AM EDT Thursday for Coastal Camden- Coastal Glynn. High Rip Current Risk through late tonight for Coastal Camden- Coastal Glynn. High Surf Advisory until 10 AM EDT Thursday for Coastal Camden- Coastal Glynn. Flash Flood Watch from 2 PM EDT this afternoon through late tonight for Appling-Atkinson-Bacon-Coffee-Jeff Davis. AM...Tropical Storm Warning for Coastal waters from Altamaha Sound to Fernandina Beach FL out 20 NM-Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM. Small Craft Advisory until 3 PM EDT Thursday for Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM-Coastal waters from St. Augustine to Flagler Beach FL out 20 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. && $$ Nelson/Hess/McGinnis/Elsenheimer/Wolf