Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/01/22
Area Forecast Discussion
National Weather Service La Crosse WI
1010 PM CDT Fri Sep 30 2022
.DISCUSSION...(This evening through Friday)
Issued at 230 PM CDT Fri Sep 30 2022
Key Messages:
- Predominantly dry and seasonal weather into early next week.
- Rain possible midweek, followed by cooler weather.
Tonight through Monday - Seasonal Weather w/ Pesky Sprinkles
The overall forecast for the next four days features little
variability in the pattern owing to a upper level Rex Block that
develops in conjunction with a cutoff low over the northern
Rockies. There is minimal spread in the NBM temperature inputs for
this period, thus confidence in the forecast temperatures is
high. Seasonal temperatures with highs in the 60s to low 70s can
be expected each day with periods of sun and clouds.
The one fly in the ointment is the persistent risk for a stray
sprinkle/shower that dots the forecast through the weekend. A
modified plume of mid-level moisture streaming northward from the
tropical Pacific and interacting with a quasi-stationary zone of
310K isentropic ascent wrapping north and east over the Northern
Plains is the culprit for this precipitate. The low-levels are
quite dry given the easterly flow off a Great Lakes high and
overall impacts should be minimal. Nevertheless, the showers today
have outperformed the deterministic and certainly the ensemble-
based guidance and it is likely that this trend will continue into
the weekend. For now have increased the mention of sprinkles in
the forecast through Sunday with the idea that more targeted PoP
increases be made as the showers manifest themselves upstream.
Tuesday/Wednesday - Increasing Rain Threat
The aforementioned Rex Block swings eastward and reorients itself
with a central Appalachian low for Monday into Wednesday. In
doing so, this allows the northern Rockies low to advance eastward
towards the Dakotas and open into a shortwave trough. The
upstream block presents a challenge to the timing of this wave as
it approaches the region Tuesday into Wednesday. NBM cluster
analysis show the various ensemble members pretty evenly split on
the timing of the wave, with the two solutions meaning the
difference between precipitation arriving Tuesday night versus
Wednesday afternoon. Rainfall amounts and overall impacts look to
be light no matter how one slices the data. PoPs for this period
are therefore low and broad-brushed as a result of this guidance
spread.
Thursday/Friday - Cooler Weather
A solid signal exists that a pattern change is shaping up for the
end of next week as a seasonably deep longwave trough digs
southward from north-central Canada into the Great Lakes. The
details of this wave, such as its position and amplitude, remain
somewhat nebulous with no clear cut signal in the ensemble
clusters. However, what is certain is that there will be a cooling
trend at the end of the week, just exactly when and how cold
remain the topics up for debate. The 12Z consensus guidance shows
Thursday night being the next potential for a widespread
frost/freeze over the region.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1010 PM CDT Fri Sep 30 2022
CIGS: SCT-BKN VFR mid/upper level clouds expected through Sat night,
associated with ripples in the upper level flow/warming in the mid
levels.
WX/vsby: persistent isentropic upglide through the mid level
saturation should continue to spark mostly afternoon -shra Sat.
Currently layout of the forcing suggests chances will mostly hold
west of the Mississippi river. Where the rain falls accums would be
minimal with no impacts to vsby anticipated.
River valley fog potential at KLSE tonight...
If NO high/mid clouds (SCT/SKC instead): near ideal setup for fog in
the river valley, spreading onto the airport (low T/Td spread,
favorable wind fields). 1/4SM would be likely for 1-3 hours coupled
with BKN002 - centered around 12z.
If YES to high/mid cloud (BKN): fog and/or stratus development will
be inhibited and the threat for fog/LIFR cigs at KLSE is diminished.
With current satellite and RAP RH fields pointing to mid clouds
spreading in overnight, will continue to hold with BCFG and watch
trends closely.
Winds: east/southeast through the period, holding under 10 kts.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Skow
AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Boston/Norton MA
1005 PM EDT Fri Sep 30 2022
.SYNOPSIS...
Large high pressure nearby will keep our weather dry tonight.
Moisture from the remnants of Ian will bring steady rain on
Saturday to the areas south of the Massachusetts Turnpike with
spottier lighter showers expected further north. Rain continues
across the south coast on Sunday, but should see a drying trend
elsewhere as a high nudges in. Strong gusty winds on Sunday
into parts of Monday. The remnants of Ian will be nearby early
to mid night week, which would bring chances of rain from time
to time. Drier late in the week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
1005 PM update...
Northern edge of rain lifting north across NJ and approaching
NYC. However, RAP shows rather dry air in the 925-850 mb layer
and rain is falling out of a mid deck so the leading edge is
likely sprinkles. Will see some light rain or sprinkles move up
along the south coast after 06z, but steadier rainfall will hold
off until daybreak. Forecast on track.
Previous discussion...
A ridge of high pressure will remain anchored across New England
tonight. Meanwhile...Hurricane Ian which just made landfall this
afternoon in South Carolina will lift into North Carolina
tonight. A warm frontal boundary will develop to the east
northeast of this system and be located south of Long Island by
daybreak. This may allow for some light rain to develop near the
south Coast as well as the Cape/Islands toward daybreak Saturday.
However, the vast majority of the night will feature dry
weather with just mid/high level cloudiness. Low temps should
drop into the middle 40s to the lower 50s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Highlights...
* Period of Steady Rain expected Saturday south of I-90 with
the highest risk for heavy rain near the south coast
* Sharp Cut-off in rain shield in the vicinity of I-90, but 25
miles in either direction make this a very difficult forecast.
Details...
Saturday...
Quite the challenging forecast on Saturday with the likelihood
in a sharp cut-off to the main rain shield. This is expected to
be in the vicinity of the MA Turnpike. We will break it down a
bit more below.
Ian/s remnants will lift northward through North Carolina and
into southwest Virginia on Saturday. However, it will transfer
some of its surface energy to the south of our waters. This will
setup a mid level/850 MB warm front near the south coast along
with Pwats climbing to 1.5 inches. While this setup is favorable
for heavy rain; the big wildcard is upper level confluent flow
that sets up across northern New England. This will result in a
sharp cut-off in the northern extent of the main rain shield.
The big question is where exactly does this occur? The 12z
guidance continues to have considerable disagreement for a
deterministic forecast inside 36 hours. The NAM remains the
most aggressive with 1 to 2 inches of rain depicted even in
northern MA. On the other extreme, the RGEM is the southern
outlier with little appreciable rainfall away from the south
coast. The rest of the guidance seems to indicate the sharp QPF
gradient somewhere in the vicinity of I-90.
Give the uncertainty...we ran with model consensus indicating
the main shield of steady rain setting up south of I-90. The
threat for heavy rain should be near the south coast, Cape and
Islands given a strong 850 mb front and its associated
frontogenesis. To the north of the MA Turnpike...thinking is
that we may see a period of spotty lighter showers but much of
the could end up just cloudy and cool. The upper level confluent
flow and low level dry air depicted on model cross sections will
become more of a limiting factor the further north one travels.
Later forecasts may certainly have to make adjustments when the
00z model data arrives. These forecasts are notoriously
challenging when there is a sharp QPF cutoff with strong forcing
to the south and low level dry air. A shift in the main rain
shield of 25 miles or so north/south of the MA Turnpike will
have a big difference in the outcome. So confidence is
definitely lower than normal in this time range.
High temps will mainly be in the 55 to 60 degree range given
clouds and rain. In fact...temps could drop into the lower to
middle 50s during steady rainfall so definitely a cool start to
the month of October.
Saturday night...
Strong high pressure around 1035 MB with weak low pressure near
the Benchmark will result in northeast low level flow. The
increasing gradient will result in northeast wind gusts of 20 to
30 mph developing overnight along the immediate coast, but
perhaps 30 to 40 mph gusts across Nantucket. The gusty onshore
flow should result in some showers at times towards the
southeast New England coast Saturday night. Further to the
northwest, deeper moisture/forcing will be more limited so while
a few showers will be possible much of Saturday night may end up
just cloudy. Low temps will mainly be in the upper 40s to the
lower 50s.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Highlights
* Still have a tight precipitation gradient on Sunday, but precip
chances decrease throughout the day. Increasing northeasterly
winds/gusts. Wind Advisories may be needed for parts of the region.
* The combination of gusty winds and building seas may cause some
beach erosion or minor coastal flooding Sunday into early next
week.
* Dry for most on Monday, but rain forecast will be tricky heading
into midweek as it will depend on the track of the remnants of
Ian. At this point best shots for rain are across coastal areas.
* Temperatures remain cooler than normal for much of the extended.
Sunday...
Caught between the remnants of Ian over the Mid Atlantic, ridging
over southern New England and a northern stream trough digging
across Quebec through northern New England. A 1030+ mb high will
build into Quebec, while a secondary low develops along a retreating
warm front.
Confidence much higher in strengthening northeasterly winds as the
pressure gradient tightens and we mix down a 30 to 40+ kt 925 hPa
jet. Did bump up the wind speeds/gusts toward the NAMNest guidance
to bring things up a bit. Confidence was high enough at this point
to hoist a Gale Watch through Sunday into parts of Monday for our
waters. Think that there will be spots along the coast where Wind
Advisories will be needed especially given it should not be
difficult to mix down these winds per NAM/GFS Bufkit soundings.
Still considerable uncertainty in the forecast with a tight
northwest to southeast precipitation gradient across our region.
This is a result of the shortwave sliding through northern New
England, which will shunt any deeper moisture to the S/SE. Best shot
for rain will be during the morning timeframe as the shortwave will
still be digging toward the region. Should see this wave moving in
late in the morning through the afternoon and gradually push
activity offshore. Best shot for more widespread rains will be along
the south coast, but especially the Cape/Islands. Will need to keep
a close eye on these spots as the 1.5-1.75 inch PWAT plume is not
too far offshore.
Did bump down high temps across southern New England toward the 50th
percentile of guidance given the northeasterly winds. Expect most to
see highs in the mid/upper 50s. Lastly, given the prolonged
northeast winds and building seas, it is not out of the question
there could be some minor coastal erosion during the afternoon high
tide for portions of the east coast.
Monday...
The remnants of Ian rotate around the Mid Atlantic on Monday, while
a ridge builds over the western/central Great Lakes. High pressure
will continue to assert itself into our region as it builds into the
Great Lakes. Should see a low develop/deepen off the Carolina coast.
Anticipating dry and quiet weather for much of the region on Monday.
There could be some spotty rain across the south coast given we`ve
still got a 20-30+ kt low level jet moving offshore. This could
provide enough lift to bring some light rain, but moisture will be
meager as it lowers to the 0.5-0.75 inch range. Once again bumped
down temps a bit from the NBM given the prolonged onshore flow.
Highs again in the mid to upper 50s.
Fortunately expect the gusty winds to gradually diminish across the
interior as the pressure gradient relaxes due to the high building
in. Still will be breezy along the coast with gusts of 20-30 kts
during the morning lowering to 15-25 kts by the afternoon. Still
could have some minor coastal erosion during the afternoon high tide
for parts of the east coast.
Monday night through Wednesday...
Considerable uncertainty through this timeframe as the remnants of
Ian get pulled into the jet and eventually kicked out to the
northeast. Does appear that there will be chances of rain late on
Monday through Tuesday and perhaps into Wednesday.
Anticipate the upper energy associated with the remnants of Ian to
rotate near/south of southern New England late Monday/Tuesday before
lifting out on Wednesday at some point. All clusters at this point
indicating some precipitation across our region, so have stuck with
NBM slight chance to chances of precipitation. Appears that any
precip would be light at this point, but it will largely depend on
the track of a deepening low south of the region. High temps range
from the mid 50s to the mid 60s.
Late in the week..
Appearing drier late in the week with some ridging on Thursday
before flow becomes more cyclonic late Thursday into the weekend.
Given the uncertainty from Monday night through Wednesday not
certain how things will evolve late in the week especially as Ian
gets absorbed into the flow. Temperatures increase on Thursday as we
tap into southwesterly warm air, but cool down late in the week
under more cyclonic northwesterly flow. Highs Thursday range from
the mid 60s to the mid 70s. Should cool into the 50s and 60s on
Friday.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight...High confidence.
VFR conditions for the vast majority of the region. Will need to
keep an eye on locations along the south coast as am already
seeing some 2.5-3 kft ceilings spreading in. This has not been
handled by guidance well. Think best opportunity for MVFR to
spread into south coast is in the 09-12Z window. Light NE
winds.
Saturday...Moderate confidence.
MVFR conditions develop south of the MA Turnpike during the
morning hours and lower to IFR levels during the afternoon. To
the north of the MA Turnpike, some light showers may develop
but areal coverage/duration will be more limited. VFR conditions
may persist in these locations or only trend to borderline MVFR
levels for a short time. The northern edge of the main rain
shield still remains uncertain; so while we are thinking it
will be in the vicinity of I-90 it has the potential to shift
20-40 miles north or south. NE winds may gust to 20-25 knots on
parts of the Cape and Islands.
Saturday night...Moderate Confidence.
Low end VFR to MVFR ceilings mainly expected Saturday night.
The lower/MVFR conditions will generally be south of the MA
Turnpike, but these lower ceilings may spread northward toward
daybreak based on Bufkit Soundings. Bulk of the leftover rain
should be towards the southeast New England coast. NE winds
gusts of 20 to 30 knots expected to develop along the immediate
coast by daybreak Sunday and perhaps near 35 knots in Nantucket.
KBOS Terminal...High Confidence in TAF.
KBDL Terminal...High Confidence in TAF.
Outlook /Sunday through Wednesday/...
Sunday: Mainly VFR, with local MVFR possible. Strong winds with
gusts up to 40 kt. Slight chance RA.
Sunday Night: VFR. Windy with gusts up to 35 kt. Slight chance
RA.
Monday: VFR. Windy with gusts up to 30 kt. Slight chance RA.
Monday Night: VFR. Breezy. Slight chance RA.
Tuesday: VFR. Windy with local gusts up to 30 kt. Slight chance
RA.
Tuesday Night through Wednesday: VFR. Breezy. Slight chance RA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Saturday night...High Confidence.
High pressure will still be in control of our waters tonight, so
expect winds/seas to generally remain below small craft advisory
thresholds. However, wave of low pressure developing south of
Long Island coupled with strong high pressure over Quebec will
result in an increasing pressure gradient. NE wind gusts will
increase to between 20 and 30 knots on Saturday with the
strongest of those winds across the southern waters.
Therefore...we have issued small craft headlines for those
locations. Wind gusts should further increase towards 35 knots
near daybreak Sunday...so Gale Watches have been issued for all
waters very late Saturday night and into Sunday.
Outlook /Sunday through Wednesday/...
Sunday: gale force winds with gusts up to 40 kt. Rough seas up
to 11 ft. Chance of rain.
Sunday Night: Strong winds with gusts up to 40 kt. Rough seas
up to 12 ft. Chance of rain.
Monday: Strong winds with gusts up to 35 kt. Rough seas up to
12 ft. Slight chance of rain.
Monday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 11 ft. Chance of rain.
Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 10 ft. Chance of rain.
Tuesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Rough seas up to 9 ft. Chance of rain.
Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 20 kt. Rough seas up to 9 ft. Chance of rain, isolated
thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Watch from late Saturday night through Monday morning for
ANZ230>237-250-251.
Small Craft Advisory from 8 AM Saturday to 2 AM EDT Sunday for
ANZ231>235-237-254>256.
Gale Watch from late Saturday night through Monday afternoon
for ANZ254>256.
&&
$$
SYNOPSIS...Frank/BL
NEAR TERM...KJC/Frank
SHORT TERM...Frank
LONG TERM...BL
AVIATION...Frank/BL
MARINE...Frank/BL
Area Forecast Discussion
National Weather Service Green Bay WI
1045 PM CDT Fri Sep 30 2022
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Saturday
Issued at 222 PM CDT Fri Sep 30 2022
The latest RAP analysis and satellite/radar imagery show high
pressure stretching from Maine to Wisconsin early this afternoon.
Precipitable water values are generally around 50% of normal
above the surface high. Higher amounts of moisture exist over
western Wisconsin and Minnesota where a weak upper level shortwave
is contributing to areas of light showers. The likelihood of these
showers sustaining themselves as they run into this much drier
airmass is relatively low. As a result, forecast concerns mainly
revolve around cloud cover and temps.
Tonight...High pressure will remain at the surface, which should
lead to another quiet and cool night. Ample dry air will exist below
700mb which should prevent showers should any precip try to move
in from the west. Otherwise, the weak upper level shortwave will
bring scattered clouds at times. Trended temps to the better
performing statistical and bias-corrected guidance.
Saturday...The large scale features only move slightly to the
east, which shouldn`t cause much change to the sensible weather.
Low level winds will shift to the northeast, which may keep temps
slightly cooler over far northeast WI than today. Under mostly
clear to partly cloudy skies, temps should rise into the middle to
upper 60s away from Lake Michigan.
.LONG TERM...Saturday Night Through Friday
Issued at 222 PM CDT Fri Sep 30 2022
A surface high over southern Canada will slowly build southeast
over the Great Lakes region late this weekend into early next
week, which should provide dry and mild weather through this
period. A weakening cold front will bring slightly cooler
conditions to the region on Sunday; however, given the dearth of
moisture this feature is expected to track through the area
without much fanfare. Temperatures will quickly rebound during the
early part of next week as the high shifts east and return flow
resumes across the western Great Lakes region.
The next chance for precipitation will be Wednesday and Wednesday
night as a strong cold front sweeps through the area late
Wednesday into Wednesday night. The front will usher in a much
colder airmass across the area as 850 mb temperatures plummet into
the single digits below zero. This cold push of air will keep high
temperatures limited to the 40s and 50s by the end of next week,
with some lake effect clouds and showers at times behind the
front, especially across northern Wisconsin. Some snow could mix
in at times at night across the far north starting late Wednesday
night; however, accumulations are not expected during this period.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1044 PM CDT Fri Sep 30 2022
Fog will be the main aviation concern. Patchy fog was beginning
to develop across the area in the late evening hours. Look for the
fog to continue to expand across the area. HREF/SREF
probabilities continue to show the Fox Valley having the best
chance of VLIFR/LIFR conditions, so will keep the 1/4 mile
visibilities. Trends will need to be monitored overnight at the
other sites, where 1/4 to 1/2 mile fog will be possible where
skies stay clear. The ground fog will burn off/lift by 13-14z
Saturday morning. Otherwise, some mid-high clouds will be found
across the area at times with light and variable winds becoming
east/northeast on Saturday.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kurimski
AVIATION.......Bersch
Area Forecast Discussion
National Weather Service Pueblo CO
313 PM MDT Fri Sep 30 2022
.SHORT TERM...(This evening through Saturday)
Issued at 312 PM MDT Fri Sep 30 2022
Key Messages:
1) Critical fire weather conditions are expected to continue until
7pm in Baca and Prowers counties.
2) Showers and thunderstorms continue across the Continental Divide
and into northern Teller and El Paso counties this evening.
3) Cold frontal passage tonight cools us down to near normal
temperatures for tomorrow.
Rest of today and tonight..
A deep low pressure system can be seen over the Northern Rockies,
making its way towards the Great Basin, on water vapor imagery this
afternoon. Ahead of this system, moist southwesterly flow is
sparking weak showers and thunderstorms across the Continental
Divide. Showers and thunderstorms are expected to spread into
northern portions of Teller county and the Palmer Divide by this
evening. A cold frontal boundary is expected to pass into El Paso
county near 6pm this evening, and continue to make its way south and
southeastward through the overnight hours tonight. Can`t rule out
some 25 to 30 mph post frontal northerly wind gusts this evening,
especially with the HRRR picking up on the potential to see
enhancement from nearby outflow boundaries. Strongest winds look to
stay in El Paso, Pueblo and maybe into Crowley counties though, as
the pressure gradient begins to weaken after sunset for the rest of
our plains. A Red Flag Warning remains in effect for Baca and
Prowers counties until 7pm, when winds are expected to drop below 20
mph. Relative humidity values will recover nicely through the
overnight hours as tonight`s cold frontal boundary helps to usher in
some more moisture for our weekend.
Tomorrow..
As the low sort of parks itself over the Idaho, Wyoming, Utah border
region for most of Saturday, additional waves of energy embedded in
southwesterly flow traverse the forecast area. This will spark
scattered to numerous showers and thunderstorms across the high
country tomorrow, especially in our central mountains. Convection
spills out into the Palmer Divide after 2pm tomorrow afternoon, when
a few strong to marginally severe storms could develop over El Paso
county. The HRRR is showing up to 35kt of bulk shear tomorrow
afternoon across El Paso county. With an overall lack of sufficient
instability to support hail growth, tomorrow`s main threat looks to
be 45 to possibly 50 mph wind gusts. With the FV3 and the NAM 3k
both showing upwards of 900 J/kg or so of DCAPE tomorrow, even as
far south as southern Pueblo and northern Freemont counties, we
could potentially see some strong to marginally severe outflow winds
across our mountain adjacent plains and into the I-25 corridor
tomorrow afternoon and into tomorrow evening. We`ll also start to
see some light snowfall on our highest peaks tonight and tomorrow,
with snow levels only getting down to about 11,000ft during this
period.
.LONG TERM...(Saturday night through Friday)
Issued at 312 PM MDT Fri Sep 30 2022
Key Messages:
1) Precipitation chances increase for most of the region through
next week, bust especially for the mountains.
2) One or two strong storms are possible along and east of the I25
corridor Sunday afternoon.
Saturday Night... Active weather is expected starting off the long
term forecast period. The the ensemble model guidance, such as the
GEFS and EPS, remain in strong agreement about a closed low staying
relatively stationary to the northwest of Colorado, with just the
southern periphery of the low influencing the southern Colorado
region. This will keep synoptic ascent and southwesterly flow,
leading to greater orographic forcing, persistent overnight. With a
modest moisture stream over southern Colorado, rain and light snow
showers, along with isolated thunderstorms, are expected to persist
during the overnight hours, mostly over the mountains. As for
temperatures, given the increase in cloud cover overnight, values
will stay above seasonal low values.
Sunday... The active weather continues into the last day of the
weekend. The ensemble guidance continue in solid agreement about the
closed low staying the northwest of the region, with just the
southern periphery being the primary influence across southern
Colorado. Given the lows position, synoptic ascent and flow aloft
will persist over the area. This will also increase the orographic
forcing over the terrain as well. With the increase in lifting, and
a modest stream of low to mid level moisture in the region,
precipitation will increase in coverage throughout the day. Numerous
to widespread rain showers and thunderstorms, along with snow
showers at higher elevations above 12,000 ft, are expected over the
mountains and mountain valleys, with more isolated rain showers and
thunderstorms along the I25 corridor and immediate eastern plains.
With the closed low in place, 0-6 km bulk shear will increase,
generally around 20-30 knots, and with the increase in moisture,
instability will also increase, but generally less than 1000 J/kg
MUCAPE. With that though, DCAPE will be around 1000 J/kg, with
pockets of higher amounts, and given that, one or two strong storms
with wind gusts up to around 50 mph will be possible, particularly
along the I25 corridor. Precipitation is anticipated to dissipate
over most of the area during the overnight, with most precipitation
remaining along the mountains as southwesterly flow continues.
Looking at temperatures, a cooler day is expected as compared to the
previous week, with most areas warming to near seasonal values. With
that said though, the eastern plains will likely warm to just
slightly above average values for this time of year.
Monday - Friday... Heading into next week, active weather remains
for southern Colorado. Agreement between the ensemble model guidance
continues, leading to better confidence in the expected forecast.
Starting Monday, the aforementioned closed low will finally push to
the east/southeast and continue to do so through Tuesday. Behind
this system, a long wave trough is expected to persist across much
of the eastern US, with small short waves embedded within that flow.
Given the influence from the closed low, and then northwesterly flow
through much of the period, precipitation chances will remain
elevated for much of southern Colorado, but especially for the
mountains. Looking at temperatures, as the closed low treks over the
area early in the week, a cold front will be pushed southward late
Monday/early Tuesday. This will drop much of the region to below
average values for this time of year. These cooler temperatures are
anticipated to continue through much of the week, as the long wave
trough will continue to push cooler air into the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 312 PM MDT Fri Sep 30 2022
VFR conditions are expected at all three TAF sites, KCOS, KPUB, and
KALS for the next 24 hours. Showers and thunderstorms are expected
within the vicinity of KCOS this afternoon and into this evening,
mainly along the terrain north and west of station. A cold frontal
boundary is expected to pass through KCOS after about 01Z this
evening, and through KPUB after 02Z. This boundary will usher in
some gusty northerly winds for tonight, and will help to increase
chances for showers and precipitation for tomorrow as well.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 PM MDT this evening for COZ236-237.
&&
$$
SHORT TERM...EHR
LONG TERM...SIMCOE
AVIATION...EHR
Area Forecast Discussion
National Weather Service Raleigh NC
1156 PM EDT Fri Sep 30 2022
.SYNOPSIS...
Post Tropical Storm Ian will continue to undergo significant
weakening as it moves northward through central NC tonight. Remnants
of Ian will linger over the area through the remainder of the
weekend and into early next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1152 PM Friday...
A Flash Flood Watch remain in effects central and northern
portions of central NC.
Quick update to reflect current headlines. All Tropical Storm
Warning have been cancelled as winds have weakened significantly
below tropical storm force. Have also cancelled the Flood Watch
across southern portions of the forecast area as the back edge
of the rain lifts north across the central and northern piedmont
and coastal plain counties.
...Previous discussion...
As of 900 pm Friday...Post Tropical Storm Ian was located along
the SC/NC state line, approximately 45 miles northeast of
Florence, SC as of 00Z Sat and will continue to track northward
into and through central NC this evening and into tonight. The
persistent dry slot on the southern and eastern sides of the
storm has brought an end to the heaviest rain across the eastern
Sandhills and southern Coastal Plain. As the system continues
to track northward, the area of heaviest rain, currently west of
I-95, will migrate northward as well. Expect conditions to
gradually improve from southeast to northwest overnight. Winds
are still quite strong and gusty, and that will continue for the
next several hours as Ian moves through the area. Generally the
winds will be north or northeasterly, with the exception of in
close proximity to the center of Ian. Winds will become more
southerly in the wake of Ian. The heaviest rain and strongest
winds should be out of the area by 12Z Sat, though some light
rain and breezy conditions are expected. Lows tonight in the low
50s NW to low 60s NE expected.
No record low max temperatures were set today, though it was close.
&&
.SHORT TERM /SATURDAY NIGHT/...
As of 300 AM Friday...
The remnants of Ian will slowly fill as it gyrates and meanders over
the southern Appalachians through midday Sunday. The remnant low is
then forecast to drift southeast, back over central NC late Sunday
and into Sunday night as it begins to feel influence of a northern
stream shortwave trough diving SE through the Great Lakes and Ohio
Valley.
Light rain chances Saturday night through a good part of the
daylight hours on Sunday should remain largely confined to the
northwestern portions of the NC Piedmont. Rain chances are then
expected to spread east and fill in during the evening and overnight
hours, with decent rainfall amounts of 0.25-0.50" possible during
the nocturnal hours.
Temperatures will be govern by the lingering CAD airmass and higher
highest chances that remain in place over the climatologically
favored Piedmont counties. Lows in the lower/mid 50s NW to lower
60s east. Highs Sunday ranging from upper 50s/near 60 NW Piedmont to
mid/upper 70s across the southern coastal plain counties.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 1245 PM Friday...
Sun through Mon night: Unsettled and chilly weather is expected.
Ian`s residual mid-upper level low will persist over SW VA Sun
morning with troughing extending down through NC and the Southeast
states, while low level CAA ramps up between low pressure off the
coast and a cold high centered over the Ontario/Quebec border. The
mid-upper low will remain well removed from the prime belt of
westerlies to the N, and as such will only wobble/drift to E VA and
the Delmarva through Mon night, as batches of energy wrap into it
from the N. During this time, the surface high will drift SSW to the
Great Lakes and weaken a bit, however surface pressures off the Mid
Atlantic coast will fall, maintaining the surface CAA along with
steady low level moisture advection into central NC. Will maintain
good chance pops, mainly across the N and E, through Mon, except
likely pops late Sun afternoon into Sun night as the low aloft
briefly drops into central NC and a surface frontal zone swings
through. Expect considerable cloudiness areawide, greatest coverage
N. These clouds plus thicknesses dropping from around 15-20 m below
normal Sun to around 30 m below normal Mon support highs in the mid
60s to mid 70s Sun then upper 50s to upper 60s Mon, the latter being
10-20 deg below normal. Lows in the upper 40s to upper 50s Sun night
then mid 40s to lower 50s Mon night as the coolest air pours into
central NC from the N.
Tue through Fri: With the mid level shortwave trough axis heading E
of our longitude, we`ll see an increasing downslope component to the
low level winds which will extend into Wed as the low aloft finally
shifts off the Mid Atlantic coast. Models favor fairly deep drying
mid week with a period of mid level shortwave ridging ahead of a
broad/minor shortwave trough over the Great Lakes into the Ohio
Valley. This feature will dampen with stronger troughing digging
over the Upper Midwest later in the week, and overall our
thicknesses will moderate back toward normal Wed and above normal
Thu. The large Upper Midwest trough will shift E into E NOAM and
push a surface cold front southeastward toward NC by Fri. Pops look
on the low side with this, given little opportunity for moisture
advection ahead of it. Will not depict a major cool down for Fri
quite yet, as model details and timing vary and it may take some
time for the cooler air to breach the higher terrain and spill into
our area. After highs in the 60s to low 70s Tue, highs should warm
back into the 70s Wed-Fri, with Thu as the warmest day, with few
to no pops. -GIH
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
As of 900 PM Friday...
24-hour TAF period: Aviation conditions will remain poor through
tonight as the center of Post-Tropical Cyclone Ian currently over
the Sandhills continues to lift north. Overall trended toward the
faster end of model guidance for this forecast based on how the
storm has trended. Widespread MVFR to IFR ceilings are expected to
lower to IFR/LIFR overnight. Meanwhile, widespread MVFR to IFR
ceilings will persist in heavy rain, but this rain has already
lifted north of FAY and the heaviest will be largely out of central
NC after midnight. Some lighter showers and MVFR visibilities may
linger overnight, particularly over the NW Piedmont (including INT
and GSO). Ceilings will gradually lift through the morning and
afternoon and should eventually scatter to VFR at FAY and possibly
RWI. However, they may remain MVFR through the end of the TAF period
at INT, GSO, and RDU. Winds will also remain strong for another few
hours, gusting up to 30-45 kts particularly in pockets of heavy
rain. However, they will gradually lessen through the night, with
gusts more in the 20-35 kt range after midnight and only in the 15-
20 kt range by daybreak. The wind direction will shift from the NE
ahead of Ian`s center to SE behind it, eventually becoming SW
everywhere by tomorrow.
Looking beyond 00z Sun: Ian will continue to weaken and slow way
down as its center drifts just slightly N then E through Sat night.
Sub-VFR cigs are likely to return Sat evening and persist through
Sat night. A slow moving upper level low will track ESE into central
NC Sun, bringing another chance of rain with mostly sub-VFR cigs Sun
afternoon into early Mon. Improvement back to mostly VFR is expected
late Mon lasting through Wed, although periods of early morning MVFR
cigs remain possible.
&&
.HYDROLOGY...
As of 220 PM Friday...
Rainfall totals so far have ranged from 1.0 to 2.0 inches in the
coastal plain to generally 0.5 to 1.0 inch the heart of the
Piedmont. With Hurricane Ian (near the Myrtle Beach, SC area at 2pm
Friday) expected to track through the Piedmont, the latest rainfall
guidance suggests a swath of heavier amounts neat Fayetteville and
just west of the Triangle toward the Triad. An additional 2.0 to
3.0 inches will be possible this evening. The steady rain today has
helped to reduce storage in area soils and most small creeks and
streams, while still well within their banks, are starting to show
more dramatic response to the rain and run off. National Water Model
Rapid Onset Flooding guidance (using HRRR qpf) highlights portions
of the Cape Fear and Haw River Basins as having the highest
probability flooding this evening, and certainly urban areas in the
Piedmont will be at risk. River flood forecasts indicate borderline
minor flooding on the Haw and Deep Rivers, as well as the Rocky
River south of Albemarle, though the trend has been downward there
with eastward track shifts.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 9 AM EDT Saturday for NCZ007>011-021>027-
038>042-073>077.
&&
$$
SYNOPSIS...RAH
NEAR TERM...KCP
SHORT TERM...CBL
LONG TERM...Hartfield
AVIATION...Hartfield/Danco
HYDROLOGY...BLS