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696 FXUS64 KMOB 072237AFDMOBArea Forecast DiscussionNational Weather Service Mobile AL436 PM CST Tue Jan 7 2025...New NEAR TERM, SHORT TERM, LONG TERM, MARINE....NEAR TERM...(Now through Thursday)Issued at 436 PM CST Tue Jan 7 2025A very cold, dry airmass will continue to filter into the local area through Thursday as a large Canadian high pressure system slowly pushes southeastward. Even under mostly sunny skies during the afternoons, highs for today will only top out in 40s, and highs for tomorrow and Thursday will be in the upper 40s to low 50s. Lows for both tonight and Wednesday night will plummet into the 20s areawide. A Cold Weather Advisory will be in effect from midnight tonight through 9 am tomorrow across the entire area for apparent temperatures (wind chills) in the 15 to 20 degree range. Another advisory will likely be needed for Wednesday night for similar wind chill values. /96&&.SHORT TERM...(Thursday night through Friday)Issued at 436 PM CST Tue Jan 7 2025The most challenging part of the forecast comes during this briefThursday night and Friday period. Upper-level troughing extendinginto the southwest US will begin to push eastwards during late week. As it does so, strong diffluence aloft will overspread much of the Southeast US. At the surface, a low pressure system is expected to develop over the western Gulf on Thursday, quickly lifting to the northeast through Friday. Latest model guidance continues to agree that the low will move onto the MS coast late Friday morning and will lift across our coastal counties throughout the afternoon. Plenty of moisture and forcing will allow for precip chances to increase rapidly throughout the period. With no instability in place, expecting this event to primarily be a widespread stratiform precip shield as opposed to convection. While confidence in precip chances remain high, precip type (particularly in the Thursday night through Friday morning time frame) continues to remain the main challenge of this forecast as temperatures over the northern half of the CWA tumble into the low to mid 30s. To understand what makes this forecast challenging, let's break down the forecast sounding analysis (based on available model guidance) for the northern CWA (Highway 84 corridor and northward) into smaller time periods... note that at this time, rain is the only precip type expected for locations south of Highway 84: Start of Thursday evening (~10.00Z)- Forecast soundings in the dendritic growth zone are beginning to saturate, while the surface to 700mb layer remains rather dry. Temperatures within this dry zone are above freezing, however, the wet bulb profile remains below freezing for the entire sounding. This would suggest that non-accumulating snow flurries would be the primary precip type, however, with the best forcing still to our west and the profile remaining rather dry at this point, not expecting precip to be ongoing at this time. Late Thursday evening into early Friday morning (03Z-09Z) - The better forcing and moisture begins moving into the area from the southwest and precip chances begin to increase. At the same time, as the surface low starts to approach the area, a low-level jet will begin to develop and move into the area. This will support a warm air advection regime, especially in the 850 to 700 mb layer. The result will be the development of a roughly 100-150 mb deep warm layer that peaks at around 3-5C. On the flip side, the onset of precip will begin to saturate the dry layer, allowing for tempsand dew points to approach the wet bulb temperature. Now with warm air advection starting, the wet bulb temperature should beginto slowly increase. That being said, a sub-freezing layer may still exist somewhere above the surface and below the 850 mb level(especially during the onset of precip). Surface temperatures at this point look to hover around 32-34 degrees which would limit any freezing rain potential. At this point, we believe that a coldrain will be the primary precip type, but with the possibility ofa lingering sub-freezing layer, a mix of rain, sleet, and snow ispossible. To match our reasoning, have went with likely to categorical rain chances, with a slight chance to chance of sleet and snow mixing in for these northern areas. Once again, due to surface temperatures remaining just above freezing and the warm nose aloft being rather stout, any frozen precip that does occur should not accumulate. We will monitor temperature trends closely over the coming days. Early Friday morning into mid Friday morning (09Z-14Z): Warm air advection will continue to slowly warm the profile. Any remnant sub-freezing layer should begin to erode and all precip should begin transitioning to a steady, cold rain. Timing of when this full transition occurs is of very low confidence and therefore a lingering slight chance of sleet and snow remains for these northern areas to account for timing uncertainties. Once the transition occurs, the frozen precip threat has ended.Remainder of the period (14Z-00z): The entire layer from 700mb to the surface will be above freezing and no frozen precip is expected by this point. /96 &&.LONG TERM...(Friday Night through Tuesday)Issued at 436 PM CST Tue Jan 7 2025The Longer term starts off with a positive tilt long wave upper trof axis aligned from the Great Lakes, southwest to Cabo San Lucas Friday evening with a fairly active high level southwest flow ahead of it taking a zone of deep moisture and larger scale ascent eastward into the southeast US. At the surface, a wave of frontal low pressure will be moving over the western FL Panhandle and southeast AL Friday evening, lifting quickly up across the Carolinas Saturday AM. Rainfall ends from west to east in the wakeof the low and frontal passage Friday night. High pressure movingeast over the deep south supports a rainfree pattern over the weekend. A nearly zonal (west to east) flow at high levels sets up early next week. There is a signal for deeper moisture andperhaps an increase in rain chances to spread eastward out of Texas to out over the Gulf. The northern extent may ease near thecoast to generate a low PoP early next week.Nights remain cold. Coldest day Saturday with highs in the 40s looking to be some 11 to 16 degrees below normal. 50s Sunday andMonday, perhaps tempered back again by Tuesday as cloud coverthickens. /10 &&.MARINE...Issued at 436 PM CST Tue Jan 7 2025Moderate northerly flow will continue through Wednesday night. Winds will shift to easterly by Thursday night. By Friday, a stormsystem will pass along the Gulf Coast bringing a strong onshore flow and building seas to the marine zones. A Small Craft Advisory will likely become necessary from the Friday through Saturday morning timeframe. Winds quickly return back to an offshore flow by the weekend in the wake of a cold front. /96&&.PRELIMINARY POINT TEMPS/POPS...Mobile 26 49 25 50 38 56 33 48 / 0 0 0 0 60 100 40 0 Pensacola 30 50 29 50 42 60 38 48 / 0 0 0 0 40 90 60 10 Destin 33 51 32 52 44 60 40 51 / 0 0 0 0 20 80 70 10 Evergreen 24 48 23 49 32 49 31 45 / 0 0 0 0 50 100 50 0 Waynesboro 23 46 21 47 33 43 28 43 / 0 0 0 0 80 100 20 0 Camden 23 45 20 46 32 44 27 42 / 0 0 0 0 60 100 50 0 Crestview 25 51 23 50 33 54 35 48 / 0 0 0 0 30 90 70 10 &&.MOB WATCHES/WARNINGS/ADVISORIES...AL...Cold Weather Advisory from midnight tonight to 9 AM CST Wednesday for ALZ051>060-261>266.FL...Cold Weather Advisory from midnight tonight to 9 AM CST Wednesday for FLZ201>206.MS...Cold Weather Advisory from midnight tonight to 9 AM CST Wednesday for MSZ067-075-076-078-079.GM...None.&&$$This product is also available on the web at:www.weather.gov/mob
