Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/12/23
Area Forecast Discussion
National Weather Service Amarillo TX
640 PM CDT Mon Sep 11 2023
...New AVIATION...
.SHORT TERM ...
(This evening through Tuesday night)
Issued at 242 PM CDT Mon Sep 11 2023
Showers and thunderstorms chances will continue tonight through
Tuesday night for the Panhandles. An isolated strong to severe
thunderstorm is possible in the far southwestern corner of the TX
Panhandle this evening. If a storm becomes severe, damaging winds
and large hail would be the primary hazards. Given lingering cloud
cover, temperatures will remain below average in the 60s and 70s.
The latest (1930z) visible satellite imagery shows persistent
cloud cover over the Southern Plains early this afternoon. Cloud
cover has been slowly decreasing across far eastern NM and west
TX. Some clearing has been noted across the southwestern TX
Panhandle and temperatures at Hereford have warmed into the low to
mid 70s. Further north, rain showers continue across the northern
half of the CWA and the showers continue to slowly drift off to
the east. A weak surface boundary is moving south across the
Panhandles and winds behind the front are out of the north around
10 to 20 mph.
Later this afternoon, showers and thunderstorms should continue to
develop off of the higher terrain to the west in NM and drift
towards the southeast. Given west TX into the southwestern TX
Panhandle has been able to clear out somewhat from cloud cover and
has warmed up slightly, some instability is present based on the
latest RAP mesoanalysis across this area. Combined with decent
shear (30-35 kts) a strong to severe storm may move across the far
southwestern TX Panhandle this evening. Main hazards would be
large hail and damaging wind gusts, with the hail threat being
more likely given the cool temperatures aloft. Rain chances will
decrease from north to south overnight.
The synoptic pattern does not have any notable changes for
tomorrow, with westerly flow remaining over the forecast area.
Another disturbance is forecast to move over the Panhandles and
will provide additional chances for showers and isolated
thunderstorms. The better chances for rain with this passing wave
looks to be across the central and southern portions of the CWA.
Rainfall totals are not looking to be all that great on Tuesday,
with the area having around a 25 to 50 percent chance of reaching
a quarter inch based on the latest NBM probabilities. Temperatures
will remain below average due to plentiful cloud cover along with
cooler air over the Plains. Highs should continue to be in the mid
60s to mid 70s.
Muscha
&&
.LONG TERM ...
(Wednesday through next Sunday)
Issued at 242 PM CDT Mon Sep 11 2023
Northwest flow aloft becomes more zonal Wednesday with continued
moisture advection keeping clouds in place across the Panhandles.
Some clearing may be allowed to occur during the day, possibly
helping to destabilize areas in the southwest TX Panhandle enough
for storms to develop. If a shortwave within the flow times out
favorably, storms could initiate in the day with enough CAPE and
shear to become strong to marginally severe. While there`s still a
good shot for rain in at least parts of the area, deterministic
guidance has trended less aggressive with thunderstorm potential
for the Panhandles, pushing better instability further south and
west with a sfc low in eastern New Mexico. But if ingredients
come together far enough east, an isolated storm or two capable of
hail and damaging winds could find itself in our CWA.
Latest trends show the sfc low traversing over the Panhandles
Wednesday night into Thursday, bringing in storms from NM while
also generating additional convection. Thursday afternoon/evening
could also be another day worth monitoring for severe weather.
Forecast soundings from the NAM and GFS both indicate the
potential for a modestly unstable and uncapped environment with
sufficient shear in place. This will likely hinge on how any
overnight/early day activity evolves, and could very well stay
quiet until the next disturbance moves in overnight into Friday.
Friday into Saturday, an upper level trough digs into the Plains
and across the Rockies, pushing a cold front southward through the
Panhandles. Once again, rain and storms look to be possible as
these features come through, but precip chances progressively
decline into the weekend through Sunday. Temperatures stay in the
70s heading into the weekend, gradually warming towards the 80s
next week.
With high PWATs in place and multiple rounds of storms feasible
during the long term, flooding concerns from additional heavy
rainfall will continue to loom. Probabilities to receive another
inch or more of rainfall are highest in the east/northeast
Panhandles where some have already been experiencing issues with
flooding. Any stronger storms will only enhance these precip
totals and in turn flooding potential.
Harrel
&&
.AVIATION...
(00Z TAFS)
Issued at 637 PM CDT Mon Sep 11 2023
MVFR conditions expected to start at all TAF sites for the 00Z TAF
period. MVFR/IFR cigs expected to continue through around 18Z
Tuesday, before conditions slowly improve to VFR cigs through the
end of the TAF period at all TAF sites. Winds to start will be
out of the northeast, becoming more southeasterly towards the end
of the TAF period with speeds of 5-10 kts.
Meccariello
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 55 70 56 70 / 20 30 50 70
Beaver OK 50 71 52 70 / 20 0 20 40
Boise City OK 49 68 53 70 / 10 20 30 40
Borger TX 57 73 58 74 / 20 30 40 70
Boys Ranch TX 54 71 57 74 / 20 40 50 70
Canyon TX 56 69 56 70 / 30 40 60 80
Clarendon TX 59 70 59 69 / 30 40 50 80
Dalhart TX 50 68 53 71 / 20 30 40 60
Guymon OK 50 70 52 71 / 10 10 20 50
Hereford TX 55 69 56 73 / 30 60 60 80
Lipscomb TX 53 72 53 71 / 30 10 20 50
Pampa TX 55 69 56 69 / 20 30 30 70
Shamrock TX 57 73 57 71 / 40 30 30 70
Wellington TX 59 74 59 73 / 40 40 40 70
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...None.
OK...None.
&&
$$
SHORT TERM...05
LONG TERM....38
AVIATION...29
Area Forecast Discussion
National Weather Service La Crosse WI
1043 PM CDT Mon Sep 11 2023
.DISCUSSION...(Tonight through Monday)
Issued at 230 PM CDT Mon Sep 11 2023
Key Messages:
- Potential for fog tonight. Lower end threat it could become
dense.
- Cool start to the work week with below normal temps, even some
potential for patchy frost in drainage areas of central WI Wed/Thu
mornings. Scattered showers/(non severe) storms Tue.
- Seasonable temps return for the latter half of the week with
scattered showers possible later Fri/Sat. No significant wetting
rains on the horizon.
* TONIGHT - fog for some.
Clearing skies, light wind field and a relatively low T/Td spread
suggests patchy to areas of fog are possible later tonight. There
are questions on how much cloud works in from the north and/or
lingers in areas to the east and south - limiters to fog. HREF shows
some support mostly from southwest WI along the Miss r into
southeast MN. Some CAMS a tad more bullish pushing that into
southeast MN. Have added more fog mention into the forecast, keeping
as patchy for the moment. Will have to a keep a close eye obs and
meso model trends - updating if needed. Can`t rule out the potential
for a dense fog advisory for some location if conditions pan out
"just right".
* COOL START TO THE NEW WEEK...scattered showers/isolated storms
Tue. Patchy frost possible Wed/Thu mornings in cold
drainage/cranberry bog region of central WI.
Upper level trough continues to influence the region through Tue,
pushing cooler, Canadian air southward along with spinning bits of
shortwave energy through the trough.
Most of the morning showers have shifted south/east of the local
area, with a smattering of light showers dropping southward across
northeast MN/northwest. CAMs suggest an uptick in coverage/intensity
as we move through the afternoon, tapping into a few hundred J/kg of
MUCAPE. Same short term models quickly diminish the activity with
the loss of daytime heating while they also outpace the upper level
forcing southward.
The front and shortwave track south/southeast across MN/WI late
morning-afternoon Tue and should provide enough punch for scattered
showers/storms. Moreso in the afternoon where 500+ J/kg of MUCAPE
will be available to aid storm development. Shear is meager, but 20
kts of 0-3km per the RAP could help the storms along. No severe
expected, and "stronger" storms would seem to be a stretch too.
Little if any moisture transport and the front does not appear
overly convergent. CAMs a bit at odds with where the higher pcpn
chances will lie, but overall scattered coverage looks to be the way
to go.
Temps will remain 5 to 10 degrees below the seasonable normals Tue
with 60s on the docket for highs for most. A slight uptick Wed with
seasonable temps then by Thu. With clearing skies and generally
light winds Wed and Thu mornings, diurnal cooling could push temps
into the low/mid 30s across drainage areas/cranberry bog region of
central WI. Patchy frost possible (likely?).
* LATE WEEK/WEEKEND: seasonable temps return, shower chances Fri/Sat
(low end chances right now with minimal amounts currently
expected).
Medium range guidance in good agreement with sliding a shortwave
upper level ridge from the plains to across the upper mississippi
river valley by 00z Thu. 850 mb temps bump from +7 C at 12z Tue to
+12 C by 12z Fri. Not a big push of warmer air, but should result in
highs climbing back into the mid/upper 70s (around 80 for some) -
seasonable for early/mid Sep.
The GEFS and EPS members take the ridge east by the weekend, driving
an upper level trough from western Canada to across the upper
mississippi river valley Fri night/Sat. SPC cluster analysis show
differences in strength/timing, with model outlay across all 4
outcomes. Individual members in both of the models` ensemble suites
show a smattering of generally light QPF in some, dry in others,
with the passage of the system. Stronger, deeper forcing could hold
well north of the local area, with only a weakly convergent
associated cold front/meager moisture transport to fuel pcpn
chances. Model blend has low end pcpn chances which look reasonable
given the model differences.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1043 PM CDT Mon Sep 11 2023
Main taf concern is potential for fog formation tonight at both taf
sites. Latest nighttime satellite imagery shows residual cloud cover
from shower activity over central Minnesota/northwest Wisconsin this
evening. These clouds are moving southeastward and will track over
western Wisconsin/parts of southeast Minnesota overnight. This could
inhibit widespread fog over parts of the area. Drier air over
southeast Minnesota/northeast Iowa will allow for mainly VFR
conditions overnight at the RST taf site...per latest guidance. At
LSE taf site overnight/Tuesday morning...MVFR condition is possible
with a slightly more moist airmass near the surface and fog could
form in river valleys/low lying areas. Have continued MVFR
condition at LSE and expect VFR conditions at RST taf sites.
Another disturbance will move over the region Tuesday afternoon.
Scattered showers/isolated storms are expected to develop after
18z Tuesday. Have continued vicinity showers at both RST/LSE taf
sites.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Rieck
AVIATION...DTJ
Area Forecast Discussion
National Weather Service Boston/Norton MA
923 PM EDT Mon Sep 11 2023
.SYNOPSIS...
Low pressure in the southern coastal waters will bring rounds of
showers and embedded thunderstorms capable of heavy rain through
early tonight. Overcast skies with fog is expected on Tuesday as
high pressure over Maine briefly builds in. A frontal system
interacting with subtropical moisture will bring soaking rains
to parts of southern New England Wednesday. Much drier and more
seasonable weather then arrives for Thursday into at least
Friday, although Hurricane Lee still could make a closer pass
late this week or next weekend. Increasing surf and rip currents
are likely to begin around Tuesday and continue into the
weekend, although there is low confidence in any other impacts.
Refer to the latest forecasts on Hurricane Lee from the National
Hurricane Center.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
9:30 PM Update...
Significant rainfall resulting in flash flooding across the CWA
continues at this hour, though some of the heaviest cells have
finally begun to move off of areas that received upwards of
4-8" of rain this afternoon; namely the Providence
Metro/Attleboro area and Springfield Metro area. Rain continues
to fall, though at a lighter intensity, across the
Leominster/Fitchburg area where a Flash Flood Emergency remains
in place as reports of compromised buildings and washed out
roads filter in.
Rain intensity is expected to wane into the overnight hours,
though pockets of intense precipitation persist over eastern
Connecticut and Plymouth county, with 1 hour MRMS precip
estimates coming in around 2 inches. Brief improvements in
visibility and ceilings will be short lived, as fog will fill in
behind the departing rain.
Previous Update..
Significant rainfall occurring across portions of north central
MA, as well as northern RI into SE MA. Unfortunately, looking
like a few more hours of rain. Updated the rainfall timing using
the latest runs of the HRRR and RAP to help highlight the
movement of the heaviest rainfall. Minor tweaks to temperatures.
Otherwise, the main theme of the previous forecast continues
overnight.
245 PM Update:
Key Points:
* Slow-moving showers with embedded t-storms to produce periods
of heavy rain and potential urban and poor drainage street
flooding through 9 PM, greatest risk in the Hartford,
Worcester, Providence to Metrowest/Greater Boston corridors.
* Impacts to the Monday PM commute expected. Localized rapid-onset
flooding possible.
Weak area of low pressure in coastal eastern NJ extends a
stationary frontal boundary seen as a windshift/local
convergence zone from southern CT into central RI and SE MA.
This is helping to focus more numerous showers and embedded
t-storms along its extent. While scattered lighter showers are
evident in radar mosaic imagery across northern and western MA,
the greatest risk for showers and thunderstorms capable of heavy
rain appears to be aligned on this existing area of localized
convergence. This feature stands to lift slowly northward late
this afternoon to early evening near or into some of our major
metropolitan areas during the PM rush. It`s a pattern that may
lead to repeated rounds of showers and embedded t- storms, one
in an environment of high warm cloud depths favoring efficient
rainfall production in even showers. Soils are highly saturated
from recent rains and some areas (e.g. Providence/Cranston) saw
flooding just yesterday. So the risk for reduced visibilities
and heavy rain capable of street flooding will exist anywhere
along the Flood Watch area, but especially aligned in vicinity
of the Hartford-Worcester- Providence-Metrowest/Greater Boston
corridor. That rains may be fairly persistent/redeveloping may
lead to street flooding, and we can`t rule out localized flash
flooding in isolated to scattered instances especially in areas
that have been harder- hit over the last 2 to 3 days. Potential
exists for local amts up to 3 inches of rain in any areas that
see persistent, heavy downpours.
Flood Watch continues in effect until late evening with no
changes made in time or location(s) from the mid-morning
expansion. Trend will be for showers and embedded storms to
collapse/shift southeast after the PM commute into the mid-
evening hours along with a decrease in overall intensity.
While rain chances trend more intermittent/spotty by late
evening and into the remainder of the overnight, stratus and fog
spreads back in westward. Fog may become rather widespread given
light NE flow, saturated ground and that most areas would have
experienced recent rain. It`s not yet certain if this situation
would rise to the level of needing either fog statements or
dense fog advisories but it is a favorable setting for fog to
develop overnight.
Temperatures only to fall a few degrees from current values,
into the mid 60s to around 70.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
245 PM Update:
Tuesday and Tuesday Night:
The weak area of low pressure bringing the more active weather
for this aftn and early tonight will have moved into the waters
well east of Cape Cod early Tue. However sfc ridging building
down coastal ME and NH will maintain onshore flow on modest NE
winds; models showing a lot of lower level RH trapped in the
lowest few km of atmosphere across much of central and eastern
sections of Southern New England. While any early-day fog should
dissipate by 10 AM, what will not will be a blanket of overcast
stratus, the net effect being little if any significant warming
despite still continued humid weather. Though there may be
intermittent and much lighter showers around in this blanket of
gray stratus clouds, Tuesday is a relative dry day of sorts
compared to recent conditions. Rain amts should be less than a
tenth of an inch in any one area. High temps were on the lower
end of guidance, using some of the higher-res NAM and a blend of
short- term guidance to bring highs in the low to mid 70s for
most of central and eastern MA and RI. Further west, there is
some optimism for more cloudy breaks into Tolland and Hartford
Counties and into western MA, with highs reaching the middle to
upper 70s.
Easterly flow continues into Tuesday evening, which will
maintain low clouds and possible development of foggy areas;
however it may not be as widespread as forecast conditions
tonight. Increasing height falls later in the overnight to early
Wed associated with frontal system bringing another round of
more active weather for Wed brings about an increase in PoP from
sub- mentionable to high chance range into our western counties.
However the bulk of rains should hold until well into Wed. Lows
mainly in the 60s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Highlights...
* Wet weather returns with soaking rain and thunderstorms
Wednesday.
* Dry weather and seasonable temperatures expected Thursday and
Friday, but we continue to monitor Hurricane Lee into this
weekend. It remains unknown whether it will directly impact
New England.
* Increasing rip current risk and high surf continues into part
of next weekend on beaches with southern and southeast
exposures.
An approaching cold front Wednesday should result in another day
of showers and thunderstorms, with locally heavy rainfall. This
front should move offshore sometime Wednesday night into
Thursday.
The main issue with this portion of the forecast remains the
ultimate track of Hurricane Lee. This will be greatly influenced
by the evolution of a mid level trough over SE Canada and the
Great Lakes. Lots of uncertainty remains in the details, which
will be important. Please keep in mind that this is a forecast
4-5 days in the future. it remains too early to focus on the
specifics. This is the plan and prepare for possibilities phase
of the forecast. Those details and expected impacts for southern
New England will come into better focus towards mid week. Stay
tuned to the latest forecasts from the National Hurricane Center
for late this week into this weekend.
Above normal temperatures expected Wednesday, then trending to
near to slightly below normal late this week into this weekend.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight: Moderate confidence.
MVFR-LIFR early, with likely ongoing SHRA/embedded TS moving
ESE 00-03z while weakening as it does so. While rain generally
diminishes in coverage/intensity, with it will be the return of
stratus and fog at IFR to LIFR levels settling in; expanding
soonest eastern areas and a few hrs later toward western
airports. Reduced confidence in the exact timing. NE winds 3-6
kt, calm at times.
Tuesday and Tuesday Night: Moderate confidence.
While fog dissipates, IFR to LIFR ceilings likely central and
eastern airports for most of the time. May see some 1-category
improvement in categories for BAF-BDL but not likely any higher
than MVFR. Spotty, light SHRA during the day. Period of steadier
rains arrives late overnight to early Wed AM. NE to E winds 4-8
kt.
KBOS TAF...Moderate confidence in TAF. IFR and steady/heavy
rain with visbys 1-3 SM. Low risk for TS. Rain gradually shifts
southeast ~04-06z Tue, although NE winds will draw LIFR stratus
and fog back in. Light NE winds.
KBDL TAF...Moderate confidence in TAF. Rain gradually shifts SE
00-02z although w/ fog and stratus at IFR/LIFR levels. Light
north winds.
Outlook /Wednesday through Saturday/...
Thursday: VFR. Breezy. Slight chance SHRA.
Thursday Night: VFR. Breezy.
Friday: VFR. Windy with areas of gusts up to 30 kt.
Friday Night: VFR. Strong winds with gusts up to 45 kt. Slight
chance SHRA.
Saturday: VFR. Strong winds with gusts up to 55 kt. Chance
SHRA.
Saturday Night: VFR. Strong winds with gusts up to 45 kt.
Slight chance SHRA.
Sunday: Windy with gusts up to 35 kt. Slight chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
245 PM Update:
Overall high confidence.
For this afternoon and tonight: Mainly E winds around 10 kt (NE on
northern waters, ESE/SE on the southern waters) tonight. Seas 2-4 ft
on most waters. Main risk for mariners is patchy fog (locally dense)
through overnight and showers and t-storms this afternoon into
evening.
For Tue and Tue night: Winds become NE to E around 10 kt, seas
continue mainly around 2 to 4 ft, though an outside chance of a 5 ft
wave is possible on the far outer waters by early Wed AM. Fog may
continue on the waters through Tue night.
Outlook /Wednesday through Saturday/...
Thursday: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers.
Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas.
Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 11 ft.
Friday Night: Moderate risk for gale force winds with gusts up
to 45 kt. Rough seas up to 17 ft. Slight chance of rain
showers.
Saturday: Moderate risk for storm force winds with gusts up to
55 kt. Rough seas up to 20 ft. Chance of rain showers.
Saturday Night: Moderate risk for gale force winds with gusts
up to 45 kt. Rough seas up to 19 ft. Chance of rain showers.
Sunday: Low risk for gale force winds with gusts up to 35 kt.
Rough seas up to 11 ft. Slight chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch until 2 AM EDT Tuesday for CTZ002>004.
MA...Flood Watch until 2 AM EDT Tuesday for MAZ004>007-012>021-026.
RI...Flood Watch until 2 AM EDT Tuesday for RIZ001>007.
MARINE...None.
&&
$$
SYNOPSIS...Belk/Loconto
NEAR TERM...Belk/Loconto/KS
SHORT TERM...Loconto
LONG TERM...Belk
AVIATION...Belk/Loconto
MARINE...Belk/Loconto
Area Forecast Discussion
National Weather Service Grand Forks ND
1034 PM CDT Mon Sep 11 2023
.UPDATE...
Issued at 1034 PM CDT Mon Sep 11 2023
Other than one lingering shower in our southeast most activity
has ended, and most CU has dissipated with clear over a lot of our
area (a few pockets of stratus). Upstream Tds are sill in the
upper 30s and lower 40s, so there isn`t a change in expected
impacts from the last update. The main adjustments were to reflect
near term trends.
UPDATE Issued at 640 PM CDT Mon Sep 11 2023
What few showers are left are quickly weakening/falling apart with
peak heating past and sunset approaching, leading to stabilizing
BL conditions. Patchy ground fog remains possible in our far
south where BL moisture may be just deep enough, while lower Td
arrive where that main surface ridge is projected to build south
later tonight/Tuesday morning.
Clearing skies (outside of areas of stratus) are already occuring
as CU breaks up with decoupling at sunset, but we should see good
radiational conditions in our north. Upstream surface Tds are in
the upper 30s though where the ridge center is moving out of
Manitoba, lowering confidence in a frost threat (requiring 36F or
less 6ft temps). Still, RAP BL Tds do drop to around 35 after
10Z, and if those drier Tds mix to the surface as the surface
inversion steepens, a few spots may drop in the 33-36F range
(mainly in Towner, Cavalier counties in ND and eastern Marshall,
northwest Beltrami- bog areas of MN). Due to the marginal/highly
localized nature of any frost potential, I am still opting not to
go with a frost advisory. I would feel more confident in frost
potential if lower Tds were observed upstream than what I am
seeing.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 313 PM CDT Mon Sep 11 2023
-Showers and a few thunderstorms pushing southeastward this
evening.
-Some stratus/fog possible in some areas overnight
-Clearing in northern counties could drop temps close to frost
point.
Vorticity lobe on the backside of the upper trough continues to
dig down out of Canada this afternoon, and will progress
southeastwards into MN overnight. Cold front has pushed through
most of the CWA, but scattered showers continue across many of the
counties except the northwest. With 500 J/kg of ML CAPE in
portions of southeastern ND and western MN, some thunder will
continue to be possible for the next few hours. CAMs and larger
scale models are in pretty good agreement on shower and isolated
thunderstorm activity continuing to push southeastward through
this afternoon and early evening. By midnight, think we should see
the showers push fully out of our area.
Tonight, there will be some subsidence and high pressure coming in
behind the frontal boundary. However, several ensemble members
show some lingering low level moisture, particularly across our
southern and eastern counties. Think our eastern tier will stay
pretty cloudy, as there are high probabilities for low clouds and
even some fog over central ND that could drift westward. There are
even some low probabilities for stratus and fog extending from
southeastern into central ND along the edge of the surface high.
Think at least there will be some cloud cover lingering overnight,
which will have an impact on temperatures.
While the south and east look to remain cloudy with dew points in
the 40s, think there will be some drier air and clearing skies
across our northern counties. Temps should drop down at portions
of the northern Devils Lake basin and northern RRV, just a
question of how much. NBM probabilities of less than 40 degrees in
that area are between 40 and 70 percent. Confidence in 36 or less
is lower, around 10 to 20 percent, although more recent runs have
been bringing that value up a bit in portions of our far
northwest. Given upstream dew points are still pretty high in the
low 40s to upper 30s, leaned towards the middle of the ensemble
pack with low temps around 37 to 38 in our northwest. Confidence
in anything lower is not high enough to include a frost advisory
at this point.
Upper ridging between systems will nose into the Plains later
Tuesday into Tuesday night, with the surface high shifting east.
Temps should stay mainly in the 60s during the day on Tuesday even
with some sunshine, but increasing southeasterly winds Tuesday
night will keep our temps in the 40s with some upper 30s in
northwestern MN.
.LONG TERM...(Wednesday through Monday)
Issued at 313 PM CDT Mon Sep 11 2023
Wednesday and Thursday...Upper ridging comes into the Plains for a
brief period mid-week before another shortwave comes over the top of
it into the Prairie provinces and Northern Plains on Thursday.
Southerly winds will be ramping up on Wednesday as a surface trough
gets going over the High Plains. This should help boost temps back
into the 70s by Wednesday afternoon for areas along and west of the
Red. A cold front will start pushing in late Thursday, but with
warming ahead of the boundary some spots could still push 80 in the
southern Red River Valley. Some showers and thunderstorms possible
as the front pushes through, although moisture is not great and
coverage looks somewhat scattered. Instability seems fairly limited
with ensemble averages in the 100-500 J/kg range and even the
bullish NAM mostly under 1000 J/kg. Severe weather threat is
minimal. Blended solution gives 30 to 40 percent probs of any
precip as the front moves through, which seems reasonable.
Friday through Monday...Upper troughing digs into the Great Lakes
for the end of the week and into the weekend. This will bring a bit
of a cool down for the first part of the period, with temps rising
back to above average values for the first part of next week. Other
than a few isolated showers possible near Lake of the Woods with the
cyclonic flow aloft for Fri/Sat, the period seems fairly dry.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 640 PM CDT Mon Sep 11 2023
Showers are quickly dissipating across eastern ND and northwest MN
with the loss of peak daytime heating/approaching sunset. There
is still a lingering stratus layer that may survive beyond sunset
in north central MN towards KBJI that is shown by guidance to
fill back in overnight with possible IFR by 12Z before eventually
clearing later Tuesday morning. Other terminals are favored by
guidance to remain VFR through the remaining TAF period, though
there is a signal for possible fog and stratus formation in far
southeast ND and west central MN that could result in
temporary/brief aviation impacts at KFAR around 12Z (not favored
but still possible and worth monitoring).
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...DJR
SHORT TERM...JR
LONG TERM...JR
AVIATION...DJR
Area Forecast Discussion
National Weather Service Gray ME
1125 PM EDT Mon Sep 11 2023
.SYNOPSIS...
Chances for showers with few thunderstorms will continue into
the first part of tonight with localized heavy rain possible.
Cooler conditions arrive Tuesday with mostly cloudy skies and
widely scattered showers. A frontal system crosses Wednesday
into Thursday bringing widespread rain. Drier weather arrives
for the second half of the week while long period swell arrives
into the Gulf of Maine.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
1120 PM Update...The heaviest rainfall has ended. However,
pockets of moderate to heavy rain still exist in small areas,
especially in central ME. The latest CAMs do show then
persisting overnight or at least reinvigorating to some extent
in Maine well after midnight. Highest PoPs will be there
overnight with lower PoPs in NH. Probability of flash flooding
overnight is lower than this past evening, but non-zero.
7 PM Update...Focus continues to be flash flooding across
southern NH this evening as near-stationary convective banding
continues to take place. Additional isolated flash flooding is
possible on the Maine coastal plain as well.
Rainfall amounts in the Hollis NH area and surrounding towns
are likely in the 3 to 5 inch range in less than 2 hours and
flash flooding is likely occurring eventually this will rain
itself out but heavy rain is likely to continue for at least a
couple more hours.
Previously...
Subtle short waves embedded in SW flow aloft will cross the
area through the first part of tonight. These waves along with a
stationary boundary draped SW to NE through the area will lead
to an expansion of showers developing over the area. Latest RAP
analysis shows an axis of MU CAPE around 1000 J/kg arcing from
southern NH through the lakes region of Maine and NH towards
interior portions of the Mid Coast. CAMs suggest this
instability axis will hold into early this evening and then
diminishes with the setting sun. PWATs along this axis of
instability are around 1.6 inches and it is here where slow
moving convection will be possible into this evening that could
produce localized instances of flash flooding. Current flash
flood guidance in this region is around 2 to 4 inches in 3
hours. The ensemble max from the 12Z HREF does show pockets of
up 4 inches in 3 hours while the ensemble mean tops out around 1
inch in 3 hours indicating the isolated nature of heavy rain.
WPC has placed much of southern NH into the coastal plain of
Maine in a Slight Risk of excessive rainfall and will be
watching this area closely into this evening for issuing any
short fused flood products. Effective shear remains less then 25
kts so the risk for strong thunderstorms is low.
Chances for showers will continue into tonight while the risk for
convection decreases with the loss of instability. Chances for
showers decrease late tonight with areas of fog and patchy drizzle
into Tuesday morning. Lows will range from the upper 50s north to
mid 60s south.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
The boundary that has sat over New England for the past couple
of days will shift into the Gulf of Maine Tuesday. A wave of low
pressure will track along this boundary and will maintain
mostly cloudy skies will cool northeast winds. This northeast
flow and low ceilings could lead to patchy drizzle continuing
into Tuesday morning along the coastal plain. There will remain
some chances for showers, mainly across the interior.
Not much in the way of drier air will be able to work into the area
leading to more fog chances Tuesday night. Lows Tuesday night will
range from the upper 50s north to low 60s south.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Overview: Heavy rainfall may again be possible mid-week, this
time atop soils that have been dampened by weekend and early
week rainfall. With some question to its forward motion, a
renewed flooding threat is possible for day 3. In the meantime,
Lee will be working north in the open Atlantic. The ensemble
envelop remains broad, but of more certainty will be wave/swell
impacts along the coast, as well as an expanding wind field from
Lee`s center.
Details: Vertically stacked low pressure will be present north
of the Great Lakes Wednesday, with a boundary slowly tracking
into New England. With onshore flow ahead and a decent amount of
moisture with the incoming system, rain will spread across the
region Wed afternoon into Thursday morning.
PWATs do increase above 1.5in through the night, and this
combined with the frontal forcing and just enough elevated
instability could cause heavy rainfall. The bigger discrepancy
may be how quickly the front pushes through the region, as it
will be the primary focal point for periods of rain.
Any sort of regression or stalling by the low pres to the west
would cause a slower passage of the boundary with flow moving
more parallel. Additionally, southerly flow will enhance lift
located over the mountains resulting in the chance for greater
rainfall rates here. WPC`s Excessive Rainfall Outlook also
highlights a portion of the area for a Slight Risk.
The front should depart through the Thursday morning timeframe,
with just a few mountain showers into the afternoon. Drier
conditions move in overnight and through Friday. By this time,
eyes will likely be trained on the passage of Hurricane Lee.
Currently in the open Atlantic, Lee is forecast to approach the
outer Gulf of Maine into Saturday.
Impacts to the Maine and New Hampshire coastline are still
uncertain, but it does not hurt to keep a watchful eye on NHC
forecasts and any guidance on the NWS Gray page. As ANY
tropical season with coastal exposure, it does not hurt to plan
ahead and be prepared with supplies should forecasts trend more
severe. Currently of greater confidence are building sea states
in the way of swell and wave height. Lee will become a broad
storm capable of affecting a lot of water surface area. This
promotes a big fetch with long period swell expected to increase
Friday. Wave heights build Friday night and Saturday,
potentially nearing 15 ft or higher on the outer waters. Thus
high surf conditions, including life threatening rip current
risk, will be possible this weekend. Caution should be
exercised if along the coastal waters this weekend. Wave heights
decrease late weekend into early next week, but swell may
linger.
As alluded to, Lee will become broad, and this will mean an
expanded precip and wind field. Do bring some chance of rain
during this time frame, as well as gusts 20 to 30 mph. The
higher summits may be much windier, and will be something to
take note of if attempting to hike through the Whites this
weekend.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Short Term...Cigs will be around MVFR thresholds into this evening
with scattered SHRA. TSRA cannot be ruled out across the southern
half of NH into the coastal plain of Maine. Cigs lower to IFR/LIFR
tonight along with potential for fog and drizzle. Some improvement
is expected Tuesday although cigs may only lift to MVFR with
isolated SHRA. Conditions likely lower to IFR/LIFR Tuesday night in
low cigs and fog.
Long Term...Ceilings may well remain MVFR to IFR as rain passes
Wed through Thurs AM. RA will also be heavy at times during this
period, resulting in similar vis restrictions. A trend towards
VFR is expected into Friday, with thickening and lowering clouds
through the weekend. North to northeast gusts will be possible
this weekend.
&&
.MARINE...
Short Term...NE Flow will continue over the waters tonight into Monday
night while winds and seas remain below SCA thresholds. Areas of fog
will remain possible over the waters with isolated
thunderstorms possible into this evening. Fog chances continue
Monday into Monday night.
Long Term...SCA conditions may be across much of the coastal
waters in the form of waves around 5 ft. A front will slowly
pass over the waters Wed night into Thurs morning. Wave heights
may remain elevated ahead of Hurricane Lee, which will be
nearing the Gulf of Maine Saturday. A broadening wind field will
drive increased swell and wave heights towards the region. Waves
in the outer waters may near 15 ft or more. Gale force winds may
be possible Saturday into Sat night.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
SYNOPSIS...
NEAR TERM...Ekster/Schroeter
SHORT TERM...Schroeter
LONG TERM...Cornwell
AVIATION...
MARINE...
Area Forecast Discussion
National Weather Service Northern Indiana
1110 PM EDT Mon Sep 11 2023
.SYNOPSIS...
Issued at 741 PM EDT Mon Sep 11 2023
Showers will expand across much of the area this evening and
overnight, before ending by Tuesday morning. Cool on both Tuesday
and Wednesday, with some showers lingering Tuesday; less so on
Wednesday. Drier and seasonably warm thereafter.
&&
.UPDATE...
Issued at 728 PM EDT Mon Sep 11 2023
A bit of a lull in showers is expected for the next couple of
hours as initial area of showers across NW areas was shifting NE
into MI. Main area of precip upstream across IL into MO was slowly
working NE but struggling somewhat as we await the main shortwave
energy to arrive. Still keeping with ramp up to a period of cat
pops through the evening but concerned maybe not as widespread as
hoped. Rest of the forecast unchanged for the time being.
&&
.SHORT TERM...(This Evening through Tuesday)
Issued at 310 PM EDT Mon Sep 11 2023
Positively-tiled trough aloft is digging into the Central Plains this
afternoon, while a leading cold front is responsible for rain
showers moving through part of our area. As suspected, thunder has
failed to pan out locally and has been removed from the forecast.
MUCAPE perhaps ticks up to 750 j/kg, but mid-level lapse rates
remain paltry near 5C/km. Curiously, the RAP does show a bullseye of
SCP near White County near 00z (8 PM EDT). This is perhaps due to a
period of increased shear (40 knots) as the base of the trough
nears. Big picture: change of thunder is extremely isolated and was
thus removed from the forecast. Likewise, in coordination with
neighbors I removed fog from the forecast tonight as well. Low
stratus looks to be the theme with perhaps pockets of heavy rain.
The 500-mb jet intensifies tonight and moisture transport from the
Gulf improves a touch (though still perhaps slightly ahead of this
system) as well resulting in widespread rain chances for most of the
forecast area overnight. A period of steady rain may persist beyond
daybreak, especially over northwest Ohio. Meanwhile, lake effect
showers will begin to impact northwest IN and southwest MI and
linger into at least early afternoon. Coverage of showers are more
questionable thereafter. For now, will hedge with a widespread 20%
POP.
Storm total rainfall through Tuesday is generally unchanged, through
perhaps a greater area of 0.50" rain total than advertised
yesterday. Much of the US 6 corridor and points north could see
0.50" to 0.60".
&&
.LONG TERM...(Tuesday Night through Monday)
Issued at 310 PM EDT Mon Sep 11 2023
One more vorticity maximum rotates through Tuesday night and
Wednesday which pattern recognition says would renew scattered
shower chances and clouds. Guidance has trended drier and sunnier,
so, will cautiously take the bait and offer a 10% POP with a mix of
clouds and sun. With large-scale troughing overhead and 850 mb
temperatures near 6C, it will be downright chilly Wednesday with
highs in the upper-60s (a normal high for early October).
Rain departs and temperatures warm Thursday through the end of the
week. The next upper-level low looks to drop in Saturday night or
Sunday, bringing a chance for rain and cooler temperatures once
again. This isn`t a slam-dunk right now, with notable model spread
at this moment.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 1058 PM EDT Mon Sep 11 2023
A cold front has been moving slowly southeast across the area with
post-frontal clouds and precipitation northwest of the front.
Overall, there has been a decrease in rainfall coverage and
intensity over the past several hours. The latest models indicate
IFR clouds will redevelop overnight and expand back into the SBN
area. The front will continue to move southeast with conditions
gradually improving after daybreak.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement from 7 AM CDT Tuesday through Tuesday
evening for INZ103.
MI...Beach Hazards Statement from 8 AM EDT Tuesday through Tuesday
evening for MIZ177-277.
OH...NONE.
LM...Small Craft Advisory from 8 AM Tuesday to midnight EDT Tuesday
night for LMZ043-046.
&&
$$
UPDATE...Fisher
SYNOPSIS...Brown/Fisher
SHORT TERM...Brown
LONG TERM...Brown
AVIATION...Skipper
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