NEAR TERM [Through Tonight]...
Although a few locations across our extreme northeastern Georgia
counties may briefly drop below freezing tonight, sustained Sfc
wind speeds are expected to remain at least in the 5 to 10 mph
range throughout the entire night.
This should greatly mitigate the chances for any significant radiational cooling across the previously defined Freeze Watch area (and we are also not quite close enough to the Arctic Ridge for an advection freeze), so went ahead and cancelled the entire watch.
Most locations across the region are expected to bottom out in the lower to mid 30s for low temps, however, these same winds which are expected to prevent the widespread freeze will create minimum wind chill readings of 24 to 30 degrees, which is quite chilly for this time of year.
Further to the south across the Florida Big Bend and Panhandle, low
temperatures are expected to reach the mid to upper 30s, with a
few lower 40s near the coast and over the extreme SE Big Bend.
Factoring in the same sustained winds, and wind chills should
generally range from 30 to 37 degrees.
SHORT TERM [Monday Through Tuesday Night]...
On Monday, the flow will turn more easterly with high pressure
sliding eastward toward the Atlantic coast.
The NAM is very aggressive in developing light showers during the day with likely to even categorical PoPs, but we believe this is overdone and have gone closer to the model consensus with 20-30 PoPs across the area. Any showers that do develop should be brief and very light.
Highs on Monday will still be rather cool with mid 50s to near 60
across the north and low to mid 60s across the south, except upper
60s across the southeast big bend.
By Monday night, a surface low will develop in the western Gulf ahead of a strong upper level low ejecting out of the southwest states.
A large area of rain is likely to spread into the western portions of the forecast area after midnight ahead of this low.
Temperatures will remain nearly steady or may actually rise slightly during the overnight hours across the western areas as strong warm advection takes over ahead of the developing surface low.
Tuesday into Tuesday night will be wet as the main system affects
the area. The threat of severe storms is low with this system, but some important uncertainties remain.
The main issues revolve around the eventual track of the surface low, and then to what extent the airmass can recover in the warm sector
ahead of the low.
The current airmass that has infiltrated the Gulf is quite cold, and there is not a lot of time for return flow to modify the airmass ahead of this approaching system.
In addition, a large area of rain ahead of the warm front could slow
the northward return of favorable thermodynamics.
On the other hand, the system will be quite dynamic with the 24/12z NAM progging a 60+ knot 850 mb jet across the area during the day with a surface low track from near Pensacola up through southeast
Alabama. In addition, the surface low is forecast to be strengthening as it passes through. This really ratchets up the forecast shear and helicity values in the NAM with 0-1 km helicity values over 400 m2/s2 and 0-1 km bulk shear approaching 40 knots over the western zones.
In addition, since the NAM has the surface low moving well inland, it also has mid 60s dewpoints penetrating well up into southwest Georgia with SBCAPE values approaching 1000 j/kg along the coast.
In short, the 12z NAM would give us a bonafide severe weather threat with damaging winds and isolated tornadoes.
Similar to the NAM, the 24/00z ECMWF had a low track inland but a
bit farther west. The 850 mb jet was also not quite as strong, but
still decent near 50 knots. Instability is less though due to slightly poorer lapse rates.
Overall, with a strengthening 1001 mb surface low moving up through Alabama, we would still need to be concerned about some severe threat on this run, although the instability and shear values are a little less than the NAM.
The 24/12z ECMWF came in similar to the previous run with an inland
track, although a couple of mb weaker with the surface low.
Moving on to the 24/12z GFS, it remains more to the southeast with
the low track, moving inland near Destin Tuesday afternoon and
across the Florida panhandle into southwest Georgia. This would
significantly limit the spatial extent of return flow, but it is interesting to note that even the GFS brings in SBCAPE values over 750 j/kg to the coast on Tuesday afternoon.
Putting everything together, the current thinking is that the main
severe weather threat will be mostly confined to areas near the
coast, especially from Panama City to Apalachicola.
However, this is still subject to adjustments as the models get a better handle on the quality of the airmass returning north.
A stronger surface low would likely mean the threat would extend farther north, and a weaker surface low that tracks more to the southeast could keep the severe weather offshore.
LONG TERM [Wednesday through Sunday]...
Most of the guidance shows the surface low and associated front
exiting to the east by Wednesday.
However, there may be some lingering shower activity into early Wednesday as the potent upper low crosses the Northern Gulf Coast.
A fairly cold airmass will move into the region on Wednesday and linger through the period, keeping temperatures below average with dry conditions prevailing after Wednesday.
Outside of some patchy thin Cirrus, virtually unlimited VFR conditions should prevail at the terminals through the early part of the period, with the presently gusty N-NE winds diminishing after sunset.
Towards the end of the period, and especially after 18Z, VFR Cigs will be on the increase.
An extended period of hazardous boating conditions is underway and
will continue through the middle of the week.
Strong northerly flow will become easterly on Monday and remain around 20 knots for most of the area.
Then as a strong area of low pressure moves along the Gulf coast Monday night into Tuesday, the winds will turn southerly and increase across the entire area.
Behind this low, strong west to northwest winds are expected on Wednesday with gale force gusts possible.
Seas are expected to reach 11 feet offshore on Wednesday.
Although afternoon Relative Humidities will still be fairly low across far northern portions of the region on Monday, moist return flow and increasing rain chances will eliminate any fire weather concerns on Tuesday.
Also, although drier air will return behind this next low pressure system, temperatures are expected to be too cold for any Red Flag concerns.
Not much change in the hydrology outlook with the next period of
significant rain Monday night through Wednesday morning.
Latest models have come in with slightly less total accumulations but
still think that some areas will see 1 to 2 inch rainfall totals.
Since we will see embedded convection, isolated heavier amounts are likely which could result in increases on smaller streams and
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 37 62 56 73 51 / 0 30 60 90 80
Panama City 43 62 60 74 47 / 10 30 80 90 70
Dothan 35 57 51 67 42 / 0 30 80 90 70
Albany 33 58 51 68 46 / 0 30 70 90 80
Valdosta 36 61 54 72 52 / 0 30 60 90 80
Cross City 41 68 59 75 57 / 10 30 60 90 80
Apalachicola 46 63 61 74 52 / 10 30 60 90 70
SMALL CRAFT ADVISORY until 10 AM EST Monday for Apalachee Bay or Coastal Waters From Keaton Beach to Ochlockonee River Fl out to 20 Nm-Coastal waters from Suwannee River to Keaton Beach out 20 NM.
SMALL CRAFT ADVISORY until 7 AM EST Thursday for Coastal Waters From Ochlockonee River to Apalachicola Fl out to 20 Nm-Coastal waters from Apalachicola to Destin FL out 20 NM-Waters from Suwannee River to Apalachicola FL from 20 to 60 NM-Waters from Apalachicola to Destin FL from 20 to 60 NM.