Rochester, Minnesota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

458
FXUS63 KARX 082322
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
622 PM CDT Tue Oct 8 2024

.KEY MESSAGES...

- Gradually warming temperatures are anticipated this week,
  eventually reaching into the middle 70s to lower 80s for
  Thursday and Friday.

- Dry conditions persist through Friday with precipitation
  chances (20-50%) returning for late Saturday and Sunday.

- A cooling trend begins this weekend with below normal temperatures
  to start next week. High temperatures by Monday likely will
  not escape the 40s and 50s. Frost/freeze will be possible
  areawide during the morning hours early next week.

&&

.DISCUSSION...
Issued at 250 PM CDT Tue Oct 8 2024

Tonight - Friday: Warming Trend Throughout The Week

GOES-16 water vapor imagery and 08.15z RAP 500mb heights show the
general synoptic pattern over the northern CONUS with a broad upper-
level trough northeast of the Great Lakes and a building upper-ridge
ejecting into the Great Plains. As a result, temperatures today were
fairly seasonable albeit slightly above average given the lack of
sky cover and increasing warm air advection with the incoming ridge.
Frost seems reasonable yet again across typical cold spots of
central/north-central WI with surface high pressure overhead
tonight. As a result, have issued a Frost Advisory for these
locations. Continuing through Friday, the aforementioned upper-
level ridge will continue to push eastward which will increase
the warm air advection regime into our region. As a result,
temperatures will continue to increase through Friday. Thursday
and Friday will be the warmest part of the week with highs in
the middle 70s to lower 80s both days.

Later into the afternoon and evening on Friday, deterministic
guidance (08.12z GFS/EC/NAM) generally agrees on pushing a
surface cold front through the region which will shift surface
flow to northerly bringing cold air advection along with it.
Currently, sub-cloud layers in current GFS model soundings lack
saturation up to around 10kft, so any precipitation would
struggle to materialize to the surface. However, with
probabilities of up to 10% for measurable precipitation in the
08.00z grand ensemble (GEFS/EC ensemble/Canadian ensemble),
would not rule out a sprinkle or two.

Saturday - Tuesday: Cooler Trend, Rain Chances Late Saturday & Sunday

Looking towards the weekend, northerly surface winds and upper-level
northwesterly flow will aid in keeping our temperatures more
seasonable for the day Saturday with median high temperatures in the
08.00z grand ensemble (GEFS/EC ensemble/Canadian ensemble) being in
the 60s for most. However, a secondary trough will swing through the
region by later Saturday and early Sunday along with a surface cold
front yet again. As this occurs, precipitation chances will increase
with the recent 08.06z EC ensemble having high probabilities (60-
90%) for measurable precipitation. This is contrasted by the GEFS
which has slightly lower probabilities (30-60%) north of I-90.
Regardless, with median precipitable waters across the GEFS/EC
ensemble of around 0.5" to 0.75", really not expecting more
significant rainfall amounts with the wave ejecting from central
Canada and having limited moisture to work with.

The larger story with this more substantial trough swinging through
will be the sharper downturn in temperatures heading into early next
week. With the general cyclonic flow perpetuating northwesterly flow
into the region through early next week, temperatures will fall well
below normal. Monday into Tuesday morning appears to be the coldest
period with 850mb temperatures in the grand ensemble having fairly
high probabilities (50-80%) of falling below minus 3 C. This is
reflected in surface temperature fields as well with low confidence
(15-40%) that temperatures would even be able to break the 50 degree
mark north of I-90 on Monday afternoon. Compared to previous
forecast cycles, the recent run of the NBM has started to catch onto
this shift as well with the operational run having widespread
temperatures below freezing on Tuesday morning and highs in the 50s
on Monday. This to some extent is consistent with the grand ensemble
where medium probabilities (30-50%) for below freezing surface
temperatures can be noted areawide.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 621 PM CDT Tue Oct 8 2024

VFR conditions through the TAF period. Light southeasterly winds
overnight shifting slightly on Wednesday to a more easterly
direction.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Frost Advisory from midnight tonight to 9 AM CDT Wednesday for
     WIZ017-029-034-042>044.
MN...None.
IA...None.

&&

$$

DISCUSSION...Naylor
AVIATION...Cecava