581
FXUS63 KABR 090159 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
859 PM CDT Thu May 8 2025

.KEY MESSAGES...

- Confidence is high that an extended stretch of hot, dry, and
  windy conditions are likely Saturday through Tuesday.
  Temperatures may break the 90 degree mark one or more days,
  which is climatologically significant for early May.

- A non-zero chance for isolated thunderstorms may develop Friday
  afternoon and early evening. At this time, severe weather is
  not expected, but gusty winds could be possible if storms were
  to develop.

- Fire danger will be elevated from Sunday through Tuesday, local fire
  fuel dryness will determine the overall threat from potential
  40 mph winds. A Fire Weather Watch has been issued for locations
  across central and northeast South Dakota on Sunday.

- Rain chances return by the mid-week, though considerable
  uncertainty remains.

&&

.UPDATE...
Issued at 850 PM CDT Thu May 8 2025

Scattered showers and a few thunderstorms stretch from north
central ND southwest into far northwest SD and into southeast MT
this evening, along and ahead of the approaching frontal boundary.
Do expect coverage of showers to wane with the loss of daytime
heating. Currently do not have any PoPs across north central SD,
so will continue to monitor for possible addition if need be.
Otherwise, forecast for the overnight hours remains basically
unchanged as we`ll see southerly breezes and temps bottoming out
in the low 50s for many areas by sunrise.

&&

.DISCUSSION...
Issued at 317 PM CDT Thu May 8 2025

Quiet conditions persist across the area this afternoon. High
temperatures have warm to the 70s to low 80s while winds remain
marginally breezy out of the south/southeast. Winds are on a
decreasing trend and will continue to weaken into the evening hours.
However, slightly elevated winds look to persist through the
overnight hours. This will keep low temperatures a bit on the warm
side with lows only falling to the low to mid 50s overnight.

Upper level ridging will be building over the western CONUS on
Friday. At the same time, a weak cold front will be pushing into the
area. this frontal passage looks to be mostly dry but with the front
pushing through during the daylight hours, a few showers to perhaps
an isolated thunderstorm is possible along or just behind the front.
Instability is minimal at or below 300 J/kg so severe storms are not
expected. Given that the low levels will be dry, some gusty winds
are possible in any shower to weak storm. Latest hi-res guidance has
come in with little to no showers developing along the front. Have
slightly reduced PoPs but still left 15-20% PoPs in place. Aside
from rain chances, high temperatures will warm to the upper 70s to
low 80s across the area while winds remain on the lighter side. Any
chance for rain will come to an end during the evening hours. Low
temperatures will fall to the 40s to low 50s overnight.

Upper level ridging persists aloft for the weekend. This ridging will
be anomalously strong for this time of year as supported by the
NAEFS ensemble. It shows 500 mb heights up to the 97.5 percentile of
climatology. This ridging will result in high temperatures warming
to the 80s on Saturday and upper 80s to even the 90s on Sunday. The
ensembles support this as they show a 60-100% chance for high
temperatures to exceed 85F. Winds will be lighter on Saturday but
low level pressure gradients will tighten on Sunday. Gusts as of
this time look to reach up to 30-40+ mph. This is again supported by
the ensembles as they show a 40-70% chance for wind gusts to exceed
40 mph. With such warm temperatures in place, humidity levels will
be very low, falling to 10-20% across the area. The hot
temperatures, dry conditions, and gusty winds will bring renewed
elevated fire danger chances to the Northern Plains. There is some
uncertainty about this potential as vegetation/fuels continue to
green. However, with continued dry conditions, locations that have
not greened up yet could struggle to sufficiently green come Sunday.
The Hot Dry Windy Index (HDWI) support this potential as it
probabilities have increased up to about a 100% chance for exceeding
the 75th percentile of its climatology. It now has a 60-80% chance
for exceeding the 90th percentile of its climatology. With
confidence increasing in potential fire weather issues, have issued
a Fire Weather Watch for central and northeast South Dakota. The
Watch is in effect from 11 am Sunday to 10 pm Sunday.

No break in the hot, dry breezy conditions for the beginning of next
week as the upper level ridge is slow to push east of the area. This
will result in similar conditions for Monday with high temperatures
again warming to the 80s and 90s, humidity levels falling to
critical levels, and a continuation of gusty winds with gusts up to
about 40 mph. Fire related headlines could be needed on Monday but
trends will be monitored over the coming days. Temperatures will
cool just a little bit on Tuesday with highs warming to the 80s and
low 90s. Winds will still be breezy but weaker then Sunday and
Monday with gusts only reaching up to about 30 mph. With humidity
levels near critical thresholds, fire danger looks to persist
through Tuesday.

Temperatures will begin to cool to the 70s and 80s for next
Wednesday and Thursday. This looks to be in response to an incoming
upper level trough ejecting into the Northern Plains. This trough
looks to bring additional chances for rains with it, especially
since there is modest agreement amongst medium range guidance. The
ensembles support this as they show increasing probabilities up to a
40-60% chance for exceeding a tenth of an inch. However, have stuck
with model blended PoPs at this time as details can still change
this far out.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 636 PM CDT Thu May 8 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. Southerly
surface winds overnight will gradually become northerly during the
day Friday.


&&

.FIRE WEATHER...
Issued at 317 PM CDT Thu May 8 2025

Hot temperatures are expected for Sunday through Tuesday with highs
warming to the upper 80s and 90s. Humidity levels will fall to
critical levels each day with humidity values down to the teens and
low 20s. Southerly winds will gusts up to 30-40+ mph Sunday and
Monday before weakening to about 30 mph on Tuesday. While these
conditions do squarely meet Red Flag criteria, there is some
uncertainty regarding fuels due to recent greening. However, even
with the uncertainty regarding greening, especially heading into the
weekend with dry conditions expected, have decided to issue a Fire
Weather Watch on Sunday. The Watch is in effect from 11 am to 10 pm
Sunday for central and northeast South Dakota. Due to the duration
of the hot, dry, and gusty conditions, additional fire related
headlines could be needed for Monday and Tuesday. However, will
continue to monitor this potential over the coming days.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Fire Weather Watch from Sunday morning through Sunday evening
     for SDZ006>008-010-011-016>023-034>037-048-051.

MN...Fire Weather Watch from Sunday morning through Sunday evening
     for MNZ039-046.

&&

$$

UPDATE...TMT
DISCUSSION...Meyers
AVIATION...TMT
FIRE WEATHER...Meyers