Calhoun Cy, Mississippi Weather Forecast Discussion

945
FXUS64 KMEG 191731
AFDMEG
Area Forecast Discussion
National Weather Service Memphis TN
1231 PM CDT Fri Sep 19 2025
...New DISCUSSION, AVIATION, FIRE WEATHER...
.KEY MESSAGES...
Updated at 1231 PM CDT Fri Sep 19 2025
- A localized flash flooding threat will continue this afternoon
  over northwest Mississippi and portions of eastern Arkansas.
- High temperatures will remain in the low to mid 90s through
  this weekend, gradually cooling through next week.
- Drought conditions are expected to persist or worsen due to a
  lack of appreciable rainfall and prolonged heat. This also
  raises wildland fire concerns through the weekend.
&&
.DISCUSSION...
(This afternoon through next Thursday)
Issued at 1231 PM CDT Fri Sep 19 2025
A more active morning that what was expected yesterday is
currently unfolding. A lead shortwave element on the southern
periphery of larger troughing across the Plains was able to
provide enough forcing for storms to form overnight with
marginally severe hazards this morning. Storms have begun to
dissipate, except for a stubborn cluster over northwest MS and
portions of east AR. Current RAP analysis shows a tongue of PWATs
around 1.5-1.7" across the southern portions of the region. With
the presence of a surface boundary draped east-west on these
areas, subtle low level flow and higher moisture have lead to a
localized flash flood threat. RFC 3-hour FFG values are between
3-4 inches, but MRMS 3-hour QPE has risen above 4 inches in
Phillips/Coahoma Counties. Training storm development, a stalled
boundary, and prior rainfall of 3"-6" in northwest MS and east AR
could prolong the threat for localized flash flooding through this
afternoon.
Taking a step back to the broader upper patterns reveals an upper
low over the Northern Plains with weak ridging over the eastern
CONUS. Water vapor imagery also shows a few shortwave impulses on
the outside of this trough, one of which moved across the area
this morning. Others still exist upstream of the region and should
eventually make their way through tonight and tomorrow. An undular
bore emanated out from this mornings storms, providing just enough
lift for isolated convection as it propagated east through the
region. The bore, in combination with another upper impulse, could
increase afternoon thunderstorms chances, especially east of the
MS River in areas that see ample afternoon sunshine. HREF guidance
shows additional storm development in the Ozark Mountains
this evening, but keep them south and west of the region. That
being said, the forecast has proven volatile in the last 24 hours.
So, this could change on a dime in future forecasts.
The upper low in the northern Plains will begin to drift north and
east tomorrow. We will remain in a belt of weak westerlies along
this southern side of the trough, allowing subtle shortwaves to
continue moving into the region. Tomorrow should be drier, barring
any overnight convection from the west, allowing for more diurnal
heating. As such, MLCAPE will increase to around 1000 J/kg into
the afternoon with a low (20%) chance for thunderstorms through
the early evening hours. Highs are expected to be in the low to
mid 90s.
A similar upper pattern will remain on Sunday, although less
amplified. NBM/NAM guidance brings decaying convection to northern
portions of the area during the morning. PoPs are low, likely a
consequence of low confidence in the placement of precipitation
and boundaries, which is reasonable at this range. A southward
pointing temperature gradient is also present with highs in the
upper 80s north of I-40 and in the mid to upper 90s to the south.
Depending on the timing of morning storms, 500-300 mb troughing
could be enough to spawn more afternoon storms down to the TN/MS
border, especially along any remnant boundaries. A similar
forecast to Sunday will exist through Tuesday, containing lower
confidence from uncertainty in any decaying overnight convection.
By mid-week, the upper trough that will keep zonal flow over the
region into next week will have decayed and merged with the
broader polar westerlies. A new wave will take its place late
Tuesday into Wednesday, quickly ejecting out of the Rockies and
into the Central Plains. Ensembles have struggled with regards to
the evolution of this trough through the past few days, split
between a meandering cutoff low and a tight, progressive wave.
This has changed this morning as LREF members now favor a southern
CONUS cutoff low at a 70%/30% ratio. This now gives more
confidence to a cooler, rainier forecast to end next week.
However, exact amounts of rain and cooling are still uncertain as
the placement and motion of the upper wave is still riddled with
variability. If the cutoff low does develop, this forecast is
likely to remain through the end of the forecast.
&&
.AVIATION...
(18Z TAFS)
Issued at 1231 PM CDT Fri Sep 19 2025
Low confidence TAF this afternoon with regard to additional
afternoon convection, especially along and west of the Mississippi
River. Will maintain the inherited Prob30`s this evening at MEM,
MKL and TUP as there is ample clearing west of the MS River, and
developing CU over central and western Arkansas. No mention for
now of additional convection at JBR.  Only minor adjustments to
Prob30 times. Otherwise, prevailing winds will be from the
northwest to southwest around 5kts this afternoon and tomorrow,
light and perhaps a bit more southerly tonight. Tomorrow should be
VFR and dry at all sites.
&&
.FIRE WEATHER...
Issued at 1231 PM CDT Fri Sep 19 2025
A complicated fire weather forecast today as decaying
thunderstorms have kept RH high through this morning. At the same
time, a localized flash flood threat continues along the MS River
in Phillips/Coahoma counties. Additional thunderstorms are
expected throughout the day, especially in areas that area able to
get plenty of afternoon sunshine. Min RH should therefore stay
around 40 percent or higher through this evening.
Tomorrow`s forecast has lower precipitation chances with minimum
RH values in the 30s and 40s. Clearer skies may allow for lower RH
values towards 30 percent and below. 20ft winds will be light
which will mitigate higher fire concerns. Wetting rain chances
increase through Sunday and into next week.
Burn bans remain in effect for portions of east Arkansas and north
Mississippi.
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...JAB
AVIATION...JDS

NWS MEG Office Area Forecast Discussion