FXUS64 KHUN 262001

AFDHUN



Area Forecast Discussion

National Weather Service Huntsville AL

301 PM CDT Thu Jun 26 2025



...New NEAR TERM...



.NEAR TERM...

(Rest of Today and Tonight)

Issued at 301 PM CDT Thu Jun 26 2025



There have been no significant changes to near term forecast 

reasoning since the update earlier this morning. Current thinking 

is that convection (in progress across the higher terrain of 

northern GA/western SC/southwestern NC) will eventually send an 

outflow boundary eastward into our forecast area, perhaps 

resulting in development of new thunderstorms across northeast AL 

in the 22-0Z timeframe. Around this same time, additional cells 

may develop across northwest AL within a zone of differential 

heating (extending northeastward into Middle TN and originating 

from precipitation earlier this morning). There is considerable 

uncertainty regarding how far west into the CWFA storms 

(originating on the outflow boundary to our east) will survive, 

but present indication are that the majority of impacts should 

occur this evening (rather than during the early morning hours). 

Given sufficiently high values of both MLCAPE and DCAPE (as 

referenced in the previous discussion), damaging downburst winds, 

large hail and vivid CG lightning strikes will be the most 

significant concerns, although flash flooding will certainly be 

possible in a few locations, as well.



Previous Discussion:

In the mid/upper-levels, a flat subtropical ridge (initially 

positioned across the central Appalachians) will translate 

southeastward over the course of the near term period as a 

shortwave trough lifts northeastward into southern Ontario, with 

the ridge becoming centered off the southeastern Atlantic Coast by

12Z Friday. As this occurs, a weak mid-level trough (initially 

across the southern FL Peninsula) will lift northward around the 

western rim of the ridge, becoming centered along the GA coast by 

12Z Friday, as well. Although light northeasterly steering flow 

will remain in place across the TN Valley today, these currents 

are predicted to collapse overnight as the height gradient aloft 

relaxes.



At the surface, our forecast area remains along the western edge 

of an Atlantic ridge centered south of Bermuda, resulting in 

light/variable environmental flow. In the absence of synoptic 

scale forcing for ascent, convection today will largely be tied to

mesoscale outflow/differential heating boundaries related to 

convection in adjacent portions of the southeastern CONUS. In 

similar fashion to what occurred yesterday, thunderstorms have 

already begun to develop late this morning in the higher terrain 

of the southern Appalachians, with additional convective 

development expected by early afternoon across central/southern 

portions of MS/AL/GA. Although lingering debris clouds and a 

convectively-overturned airmass (both stemming from widespread 

nocturnal convection last night) will likely delay convective 

initiation in our region until late this afternoon (when temps 

should finally recover into the l-m 90s), gradual cooling at the 

500-mb level and dewpoints in the u60s-m70s will support MLCAPE of

2500-3500 J/kg (if not a bit higher). This along with steep lapse

rates in the subcloud layer and DCAPE values of 1000-1250 J/kg 

range will support a risk for locally damaging downburst winds (up

to 65 MPH), large hail and frequent lightning. Additionally, 

storms will be efficient rainfall producers, and with PWAT values 

solidly in the 1.7-1.8" range, flash flooding may also occur in a 

few locations.



There are indications that afternoon thunderstorms to our 

south/east may eventually evolve into a small cluster early this 

evening as outflows merge and consolidate, with some concern that 

a similar scenario (compared to this morning) may unfold across 

our CWFA once againthis evening. Otherwise, abundant mid/high- 

level clouds will support warm/muggy conditions overnight, with 

lows in the u60-l70s.



&&



.SHORT TERM...

(Friday through Saturday night)

Issued at 1138 AM CDT Thu Jun 26 2025



Latest short term model consensus suggests that the remnants of a

weak mid-level shortwave trough will lift slowly north- 

northwestward across GA through Saturday night, around the western

edge of a subtropical ridge off the southeastern Atlantic Coast. 

However, the most significant impact that this feature will have 

on our region will be weak storm steering currents, which should 

result in slow/erratic cell motions and perhaps a greater risk for

flash flooding. Otherwise, we expect convection on Friday to be 

most prevalent across the higher terrain to our northeast and in 

the more unstable environment across southern portions of the Gulf

Coast states, with development of thunderstorms across our 

forecast area largely confined to the afternoon hours and in the 

vicinity of mesoscale outflow/differential heating boundaries. We 

will need to keep an eye to our east once again Friday night, as a

small cluster of storms originating across the Savannah River 

Valley of eastern GA/western SC may tend to spread westward across

northern GA and into the TN Valley by early Saturday morning, but

the level of uncertainty in this scenario is rather high at this 

point (especially given the weak nature of steering currents 

aloft).



A similar convective pattern will materialize on Saturday, 

although as 500-mb heights begin to rise along the northwest Gulf 

Coast, a light NW flow aloft should begin to steer convection 

southeastward once again (in a fashion we are more accustomed to),

and this may allow storms to continue into the evening/overnight 

hours, as well. Although MLCAPE values will rise into the 

2500-3500 J/kg range on a daily basis, DCAPE values both Friday 

and Saturday afternoon may be a bit lower (750-1000 J/kg) but 

still sufficiently strong to support locally damaging downburst 

winds. With afternoon high temperatures predicted to fall back 

into the u80s-l90s, we have no plans at this point to extend the 

Heat Advisory beyond its current expiration (0Z Saturday), but 

afternoon heat index readings will remain in the 95-100F range 

throughout the short term period.



&&



.LONG TERM...

(Sunday through Wednesday)

Issued at 1158 PM CDT Wed Jun 25 2025



The weak upper low will be pushed towards the eastern seaboard 

early next week as a low pressure system slides over the Great 

Lakes and its associated cold front approaches the Tennessee 

Valley. With this pattern, expect daily chances of showers and 

storms (30-60% chance), especially during peak heating in the 

afternoon/early evening. By Tuesday, rain and storm chances are 

forecast to increase (40-70%) as the aforementioned surface front 

approaches the region.



Model PWATs range between 1.7-1.9 inches from Saturday through 

Monday and, when compared with BMX Sounding Climatology, fall 

within the 75-90th percentiles. PWATs increase to over 2 inches by

midweek, which would be greater than the 90th percentile. Thus, 

showers will be efficient rainfall producers and could outperform 

current forecast rainfall totals for the long term. At least 

nuisance flooding will therefore be possible this weekend through 

early next week. As for any chance of severe storms, instability 

will be sufficient but bulk shear values are low. So, confidence 

is low in severe storm occurrence.



The good news is that with the return of shower/storm chances 

will come cooler daytime temperatures. Highs in the 85 to 90 

degree range are anticipated from Tuesday and Wednesday due to the

higher rain chances. Lows, however, will remain in the upper 60s 

to lower 70s each night.



&&



.AVIATION...

(18Z TAFS)

Issuedat 118 PM CDT Thu Jun 26 2025



VFR conditions are currently observed at the HSV/MSL terminals, 

featuring few-sct Cu beneath a layer of high-lvl convective debris

clouds. Although the risk for development of convection will 

initially remain low (in the wake of widespread nocturnal 

showers/storms), the local airmass is beginning to destabilize and

as outflow spreads westward into the region from convection 

(currently in progress across the southern Appalachians) we expect

to see new cells form across northeast AL by 21-23Z. This 

activity will progress westward with time this evening, and PROB30

groups have been indicated for HSV/23-3Z and MSL/1-5Z to 

highlight impacts from strong wind gusts and CG lightning (both of

which would prompt AWWs). As convection dissipates across 

northwest AL early Friday morning, patchy BR/FG may develop in a 

few locations that receive rainfall, but this has not been 

included in the forecast at this point. Otherwise, sct Cu will 

redevelop by 15Z, with winds remaining lgt/vrbl.



&&



.HUN WATCHES/WARNINGS/ADVISORIES...

AL...Heat Advisory until 7 PM CDT Friday for ALZ001>010-016.



TN...Heat Advisory until 7 PM CDT Friday for TNZ076-096-097.



&&



$$



NEAR TERM...70/DD

SHORT TERM...70/DD

LONG TERM...KTW

AVIATION...70/DD

