NEAR TERM [Through Tonight]...
Local radars show showers developing over our westernmost zones
early this afternoon lifting off to the northwest. We expect additional convective development as the sea breeze advances further inland. The best chance for rain will be over our SE AL and Florida zones through this evening. Widespread stratus will develop overnight along with patchy fog. Minimum temperatures will be in the lower 70s.
SHORT TERM [Sunday Through Tuesday]...
The large scale longwave pattern will amplify to commence the
period. This is highlighted by mid/upper trough that will continue
to translate EWD with axis from upper Great Lakes SWD into Wrn Gulf
yielding modest 500mb height falls. Potent shortwave moves out ahead across NE states. Ern ridge kicked Ewd with axis along Ern seaboard. Surface reflection over Nrn Great Lakes with cold front SSW across TN Valley, MS and into Ern TX. This continues to erode ridge over SE states. This places local area in warm and moist sector.
During the rest the period, trough will pivot Ewd with axis down into NE Gulf by Mon morning to along Ern seaboard by eve before
moving offshore to be replaced by upstream ridge and dry NW steering flow on Mon night into Tues. Under dampening upper support as upper low ejects NEWD, weakening cold front dragged SEWD to vcnty local area on Mon where it slows and stalls across our forecast area leaving CWA with veering winds in cloudy but warm sector.
There will be enough Q-G forcing and mesoscale boundary interactions within the warm, moist environment to trigger scattered deep moist convection Sun and Mon and possibly into Tues. Will go with 20-50% SW-NE POPs on Sun and Mon, 20-40% on Tues. For Tues, some additional tropical moisture may move far enough NEWD to impact SE Big Bend (see below).
For the entire CWA, the highest rain chances thru the period will be during the afternoon and early evening hours, when instability is maximized. Despite the increased rain chances, the expected cloud cover does not appear enough to prevent high temperatures from reaching 90 each aftn. Fog chances will increase each of the two late nights into early morning.
As far as severe weather, with such weak winds from the surface to
500mb and remnants of surface ridge, significant storm organization
appears unlikely, which should keep our threat of severe storms low.
However, there will probably be sufficient instability for a pulse
strong-severe storm or two during the afternoon hours of especially
Sunday and Monday. (SPC rates it as generally 5% or less).
Although precip water values are not expected to be excessive by summertime standards, there will be enough moisture for heavy rain rates. The steering flow will likely be very weak, which could allow heavy rainfall over very narrow bands so localized flooding is also
possible. This threat is currently not high enough to warrant any
consideration of flood watches.
LONG TERM UPDATED [Tuesday Night through Saturday]...
The long term weather, and especially the latter half remains
uncertain and is largely dependent on the development and track of
a low pressure center near the Yucatan Peninsula.
This is the remnants of Barbara currently over the Bay of Campeche and initial development will be hampered by unfavorable upper winds and proximity to land and NHC with only 10 chance of becoming tropical cyclone in next 48 hrs. Models still show differences in evolution of this system but have trended faster.
For example, now faster GFS and even faster Canadian show system picked up by upper trough late Mon or Tues which would send the low into Cntrl FL Wed and Thurs and place us on the west or drier side into the weekend. In this scenario, system would likely experience significant deep layer shear as its drawn Nwd. Other models like much slower ECMWF do not dig trough as far south and low retains more of its dimension yielding a broad weak area of low pressure over Nrn Gulf of Mex thru most of the period. In any scenario, ample tropical moisture will spread NEWD ahead of low, the question is where will that moisture end up.
For now, ECMWF has been the most consistent and will lean that way.
Still given the degree of uncertainty confidence in final evolution of system still not high. we will focus on daily scattered mainly
seabreeze focused convection each day.
Temperatures will be highly dependent on model evolution hence cloud cover, but for now will lean towards ECMWF numbers. Note, any NEWD shift of low or increase in intensity will notably alter future forecasts. For now, main impact, in any, would be on marine area with potentially heavy rain and higher winds and seas Fri and especially on Sat.
The ECP, DHN and TLH terminals will have the best chance for seeing a shower or thunderstorm through this evening but still not enough confidence to go with tempo convective groups. Went with VCTS at those sites instead.
Any convection that develops will diminish by late evening.
Overnight, expect widespread IFR cigs to develop with MVFR vsbys at most sites toward daybreak. MVFR cigs may linger into early Sunday afternoon.
Winds will continue to gradually diminish as the pressure gradient weakens considerably.
Light winds and low seas will continue until early in the work week, when a low pressure system (currently in the Bay of Campeche) moves northeastward across the eastern Gulf of Mexico and this could potentially result in heavy rains and high winds and seas by mid week.
There remains notable model differences in the intensity and track of this low so late period forecasts are likely to change as these differences are resolved. For now will just show a modest increase in rain, with exercise caution to possibly advisory level winds Tues into Thurs eve.
There are no fire weather concerns in the foreseeable future.
With all of the local rivers currently below action stage, it appears unlikely that the expected rainfall through Tuesday will be heavy and concentrated enough to produce river flooding or widespread flash flooding.
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 89 72 90 71 90 / 40 20 40 30 40
Panama City 86 74 85 73 87 / 40 20 30 20 30
Dothan 91 72 92 72 90 / 30 20 40 40 40
Albany 92 72 91 71 91 / 20 20 50 40 50
Valdosta 90 70 90 70 90 / 20 20 50 40 50
Cross City 90 70 89 70 89 / 40 30 40 30 40
Apalachicola 85 72 83 73 86 / 40 20 30 20 30