Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/27/23

Area Forecast Discussion

National Weather Service Caribou ME

 1034 PM EDT Tue Sep 26 2023

.SYNOPSIS...
High pressure will continue to prevail across the region
through the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
10:30 PM Update...Forecast remains on track. Modified temps to
cool them a bit in the northern valleys. Otherwise, no major
changes this hour.

Tonight... Expecting patchy, mainly river valley fog
again tonight as strong subsidence will be over the region with
strong upper level and surface high pressure building in from
the north. Should be a little later start to the fog than last
night since it got warmer today and we have a bit more to cool
off before relative humidities get near 100%. Should be patchy
frost in the north again, though expecting 2-3F warmer than last
night and think frost is patchy enough that we don`t need any
advisories. Clear skies tonight other than the patchy fog, the
upper level smoke, and perhaps some cirrus sneaking into the far
SW corner of the forecast area around MDI.

Wednesday...
Strong, blocking upper level and surface high pressure
remains, which will be centered immediately north of us on
Wednesday. Fog will dissipate by mid morning, leaving generally
clear skies with little if any afternoon cumulus development.
Still expecting some upper level smoke. Can`t totally rule out a
little surface smoke, as HRRR smoke model brings the smoke down
in the atmosphere some. If any smoke is at the surface, don`t
anticipate visibilities less than 10 miles. Light winds
Wednesday, with highs around 70.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Upper lvl high pres ovr QB will cont to prevail thru Thu Ngt
with cont`d dry conditions and gradually warming sfc temps. Fri
and Fri Ngt, the upper ridge will break down somewhat as s/wvs
track ewrd from the Midwest and Nrn Can well S and N of the FA
as the Rgn remains in a neutral zone between a Nrn and Srn
stream upper jet streams. This will keep the FA precip free durg
this tm, but with increasing cldnss. High and low temps will
remain sig abv normal durg this tm. Will keep a mention of late
night til mid morn patchy rvr fog for each day.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Long range models re-build the upper lvl ridge/high pres ovr
the FA from the W ovr the weekend and then conts to hold it ovr
the FA thru Mon forced by amplifying anomalous troffing ovr the
Wrn U.S. Temps will cont sig abv normal ovr the Rgn durg this
tm frame, perhaps warmer on Mon than we are currently advertising.
However, the uncertainty of tmg of a semi-back door cold front
from Nrn Can for late Mon/Mon Ngt keeps us from going much abv
lower to mid 70s on Mon attm. All 12z dtmnstc models agree on
the prospect of a decent cold frontal passage Mon Ngt into Tue,
but disagree on the tmg with the GFS fastest and the CanGem
slowest. For now, we show some increase in cldnss and slgt chc
shwrs msly across the N by Mon Ngt followed by fair, breezy,
cooler conditions for Tue.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: VFR into this evening. Periods of IFR/LIFR visibility
possible late tonight once again with patchy river valley fog.
Sites with best shot of fog in TAFs are PQI, HUL, and BGR. Think
that fog will set in a little later than last night. N winds
5-10 kts today, diminishing to 5 kts or less tonight into
Wednesday. VFR Wednesday with fog dissipating by about mid
morning. Some smoke aloft, not expected to impact surface
visibility.

SHORT TO LONG TERM: Wed Ngt - Sun...all TAF sites mainly VFR
with patchy IFR clgs/vsbys in late ngt til mid morn patchy fogRest of this Afternoon...
Warming up nicely today, with mid to upper 60s for highs with a
light north breeze. Not a cloud in the sky, not even any
cumulus, with very strong upper level and surface high pressure
continuing to build in from the north. However, there is some
smoke aloft, coming all the way from Northern Alberta, that is
dimming the sunshine a bit. The smoke is not impacting surface
visibility or air quality.possible each day spcly at KPQI,
KHUL, and KBGR.

&&

.MARINE...
NEAR TERM: Winds and seas easily below small craft levels. No
marine fog expected through Wednesday.

SHORT TO LONG TERM: No hdlns xpctd attm, with wv hts ovr outer
MZs perhaps apchg 5 ft by late Sun into Sun Ngt. Kept close to
blended wv model wv hts this update with wv pds msly between
10-12 sec durg these ptns of the fcst.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.

&&

$$

Near Term...Bloomer/Foisy
Short Term...VJN
Long Term...VJN
Aviation...Bloomer/Foisy/VJN
Marine...Bloomer/Foisy/VJN



Area Forecast Discussion

National Weather Service Twin Cities/Chanhassen MN

 1102 PM CDT Tue Sep 26 2023

.DISCUSSION...(This evening through Tuesday)
Issued at 302 PM CDT Tue Sep 26 2023

KEY MESSAGES:

- Well-above normal temperatures expected late this week & through
  the weekend.

The slow-moving area of low pressure that brought our first
appreciable widespread rainfall in months continues to slowly exit
the region to the southeast, but cloud cover & a few showers still
remain with lingering cyclonic flow in its wake. Some breaks in the
cloud cover are possible tonight, & fog will likely develop again in
these areas of clearing given the moist ground & cool daytime
temperatures. We remain under the influence of the slow-moving low
for one more day tomorrow, with continued cool temperatures & mostly
cloudy skies - although more persistent clearing of the cloud cover
looks possible by tomorrow evening.

The main weather story this week begins on Thursday, as broad
ridging develops over the Great Lakes through the weekend, leading to
well-above normal temperatures along with a chance for near-record
high temperatures. Thursday should be dry with temperatures warming
to near-normal values, but continued southerly winds & warm advection
will allow for temperatures to approach 80 across much of the area
on Friday. We’ll have to keep an eye on the thunderstorm potential
Friday night, as ensembles suggest an unstable atmosphere with high
likelihoods of greater that 1000 J/kg MUCAPE & strong deep shear
values in the vicinity of a slow-moving front expected to end up
somewhere over the Dakotas/Minnesota Friday night. Current guidance
suggests the bulk of the thunderstorm activity will end up north &
west of the area but we will have to monitor the speed of the front &
where it ends up Friday.

Temperatures will continue a warming trend through the weekend as
the ridge peaks in strength over the western Great Lakes by Sunday.
Current middle-of-the-road NBM guidance suggests highs in the mid-80s
are likely over the weekend along with very warm overnight lows in
the mid to upper 60s. However, a few individual model members suggest
the potential for highs in the upper 80s & even 90s, especially
across western MN. This isn’t shaping up to be a typical September
“dry heat” either, with moist southerly flow bringing summer-like dew
point values in the mid to upper 60s into the area. For reference,
average highs for late September are in the upper 60s with overnight
lows around 50, with record high temperatures generally in the upper
80s. Rain/thunderstorm chances will generally be suppressed by the
strong ridging overhead, but can’t totally be ruled out if any
frontal boundaries linger over the area. Looking ahead, the strong
ridging overhead will begin to weaken early next week, but continued
above-normal temperatures look likely through the first week of
October.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1052 PM CDT Tue Sep 26 2023

As expected, cloud heights have begun to drop, though it started in
southern MN, with the lower cigs expected to build north through the
night. Outside of RWF/MKT, the going TAFs were trending well, so
didn`t change much with respect to timing MVFR or lower cigs back in.
Confidence is low with cigs on Wednesday and how quickly they`ll
improve. The 00z HRRR came in similar to the 18z run with decent
coverage on scattered showers for Wednesday afternoon, so did bring
in precip mentions to MSP/RNH/EAU.

KMSP...Shower threat could start as early as 15z. No TS is expected,
with rain rates lower even than what we saw today as we see our last
gasp from the upper low that has plagued us since the weekend. For
cigs, there is potential for IFR cigs in the morning, though the LAV
has been too aggressive with how low it takes cigs since the weekend,
so maintained MVFR cigs for now.

/OUTLOOK FOR KMSP/
Thu...VFR. Wind SE 10-20 kts.
Fri...VFR. Chc TSRA overnight. Wind S 15G25 kts.
Sat...VFR. Wind SE 10-15 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&

$$

DISCUSSION...ETA
AVIATION...MPG