Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/24/24
Area Forecast Discussion
National Weather Service Boston/Norton MA
1005 PM EDT Wed Oct 23 2024
.SYNOPSIS...
A weak cold front arrives late tonight and could bring a few
brief showers, followed by somewhat cooler conditions Thursday
but still above normal. Generally dry and pleasant weather is
on tap for Friday and Saturday with a brief shot of chilly
temperatures Sunday into Monday behind a cold frontal passage.
High pressure then shifts east of the region early next week
allowing unseasonably warm temperatures to return Wednesday and
especially by Thursday. The extended period of dry weather also
looks to continue well into next week with just a low risk for a
few brief scattered showers on Saturday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Made some tweaks to rainfall chances this evening based on the
last few runs of the HRRR, which appeared to be handling the
band of showers across NY state pretty well. Clouds expected to
arrive overnight. Low level dew points surged upward this
evening, increasing the risk for rainfall to reach the ground.
Still not very confident in measurable amounts, but did
increase PoPs for portions of the western half of southern New
England.
Minor tweaks to temperatures as well.
7 PM Update...
Upper trough approaches from the Gt Lakes tonight with the
accompanying cold front moving across SNE 06-12z. This is a
sharp trough axis with a narrow band of 1"+ PWATs moving across
the region ahead of the trough. However, much of the global
guidance is pretty muted with QPF and suggest a mostly dry
fropa as the column does not fully saturate. That being
said...based on latest radar trends and the last few runs of the
HRRR opted to include the risk for brief isolated showers
overnight. Clouds will be increasing ahead of the front and pre-
frontal SW flow will result in milder temps with lows mainly in
the 50s.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday...
The upper trough axis moves through during Thu with closed low
possibly developing south of New Eng. This will slow the
eastward progression of the front but not until it moves off the
coast by 12z. A few morning showers will be possible with the
trough passage, mainly near the south coast. Drier air will
gradually move in from west to east with any lingering morning
clouds giving way to increasing sunshine. Airmass not all that
cool behind the front with 925 mb temps 8-12C so while it will
be cooler, temps will still be above normal with highs mid-upper
60s, cooler interior high terrain. Becoming breezy behind the
front with soundings supporting N-NW gusts to 20-25 mph, perhaps
up to 30 mph for the Cape and Islands.
Thursday night...
Upper trough moves offshore with rising heights and surface high
pres gradually building in from the west. Expect clear skies
with diminishing wind, especially interior but winds will stay
somewhat gusty along SE coastal MA and Cape/Islands. Coolest
temps in the low- mid 30s will be in western MA where best
radiational cooling, with mildest temps mid-upper 40s
Cape/Islands. Low temps mostly upper 30s and lower 40s
elsewhere.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Key Points...
* Extended period of dry/tranquil weather continues into next
week
* Low risk for brief scattered showers Sat...but may remain dry
* Pleasant Fri/Sat with a brief shot of chilly air Sun into Mon
* Unseasonably warm temps return Wed & especially Thu...record
highs?
Details...
Dry and tranquil weather will continue through much of next
week. A ridge of high pressure builds into the region Fri and
slides to our east Sat as a cold front approaches. There is the
low risk for a brief round of scattered showers Sat...but model
guidance currently does not show any QPF as the front is
moisture starved. We can not rule out that the models begin to
indicate a bit better chance for a few showers as we get closer
to Sat...but either way not expecting much if anything. Main
impact with the front will be a shot of chilly air Sun into Mon.
Highs should mainly be in the 60s Fri & Sat...but more like 50s
Sun. Mon should be the chilliest day with the chilly start and
high pressure overhead limiting mixing. Highs Mon likely remain
in the 40s in parts of the high terrain and struggle to get too
much passed 50 elsewhere. It will be quite chilly Sun
night...when many locales may drop well down into the 20s to the
lower 30s as high pressure builds over the region.
This high pressure system will slide east of the region by Tue
and Wed. This will allow a return southwest flow of much
milder air back into the region Wed and especially by Thu. The
EPS/GEFS anomalous upper level ridging setting up across the
mid-Atlantic coast. Southwest flow should allow highs to
probably reach back into the 70s by Wed and perhaps taking a run
at 80 by Thu. Still quite a ways out...but certainly may
challenge a few record highs given strong support from the
EPS/GEFS guidance.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00z TAF Update...
Tonight and Thursday...Moderate confidence.
Mainly VFR conditions...but may see enough marginal moisture
return to result in a period of MVFR to even localized IFR
conditions towards the south coast, Cape and Islands overnight.
But thinking it does not make it much further north than that.
SW winds shift to NW 06-12z behind a cold front with gusts to
20 kt developing during Thu. Gusts to 25 kt possible
Cape/Islands. Nothing more than an isolated brief shower or
two with the cold front...but it mainly moves across the region
dry.
Thursday night...High confidence.
VFR. Diminishing wind, but gusts to 20 kt Cape/Islands.
KBOS TAF...Moderate confidence. Some risk for MVFR cigs
developing tonight but just included SCT035 layer in the TAF
for now as confidence was not high enough. Thinking main risk is
south of the terminal.
KBDL TAF...High confidence.
Outlook /Thursday Night through Sunday/
Friday: VFR. Breezy.
Friday Night: VFR.
Saturday through Sunday Night: VFR. Breezy.
Monday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
High confidence through the end of this week.
Another round of gusty NNW winds to 25 kt will develop over
eastern MA waters during Thu afternoon and evening. Small Craft
Advisories have been re-issued for this time period. We also
hoisted Small Craft Headlines later Thu into Fri for the outer-
waters...where seas are also expected to build to 5+ feet.
Outlook /Friday through Monday/...
Friday: Winds less than 25 kt. Local rough seas.
Friday Night through Saturday: Winds less than 25 kt. Areas of
seas approaching 5 ft.
Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Seas up to 5 ft.
Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft.
Sunday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
&&
.FIRE WEATHER...
For Thursday, expecting minimum relative humidity values of 35
to 45 percent are expected. N to NW winds will gusts to 20 to
25 mph. Based on input from our area Fire Weather Partners...a
Special Weather Statement will be issued to highlight the
elevated fire weather concerns.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from noon to 7 PM EDT Thursday for
ANZ231>234-251.
Small Craft Advisory from noon Thursday to 8 PM EDT Friday for
ANZ250-254-255.
Small Craft Advisory from noon Thursday to 2 PM EDT Friday for
ANZ256.
&&
$$
SYNOPSIS...KJC/Frank
NEAR TERM...Belk/KJC/Frank
SHORT TERM...KJC
LONG TERM...Frank
AVIATION...KJC/Frank
MARINE...KJC/Frank
FIRE WEATHER...Staff
Area Forecast Discussion
National Weather Service State College PA
1119 PM EDT Wed Oct 23 2024
.SYNOPSIS...
A cold front will push through the region tonight, then high
pressure will build in behind it for late week. Another cold
front will push across the region Friday night, followed by
high pressure that will linger over the region through early
next week.
&&
.NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
A cold front, which lies across Central PA at 03Z, will push
southeast overnight, exiting the southeast portion of the
forecast area by around 06Z. Although this front is lacking
deep moisture, fairly robust large scale forcing is currently
supporting a broken line of showers and even a few tsra along
and just ahead of the front. Based on radar trends and latest
HRRR output, we will carry chance POPs for the southeast half of
the forecast area between 03Z-06Z. Any rainfall should be quite
light (<0.10 inches) based on latest near term models.
The post-frontal NW flow will be cold enough to support lake
effect stratocu and isolated rain showers/sprinkles over the NW
Mtns late this evening. However, falling inversion heights
should cause any showers to taper off after 2 or 3 AM with
clearing skies downwind of the Appalachians. See no reason to
deviate significantly from NBM min temps, which range from
around 40F over the Allegheny Plateau, to the low and mid 50s
in the Lower Susq Valley.
&&
.SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY/...
High pressure building into PA should result in fair weather
and diminishing winds Thursday. Lingering lake effect stratocu
is likely across the N Mtns during the morning. Otherwise, model
RH fields support mostly sunny skies. GEFS 2m temps return to
near average for late October, with expected highs ranging from
the mid 50s over the higher terrain of the Alleghenies, to the
low and mid 60s across the Lower Susq Valley. Model soundings
show very dry air above a weak inversion Thursday afternoon, a
signature that reliably predicts dewpoints falling below NBM
guidance.
All guidance supports fair and chilly conditions Thursday night
with min temps likely a bit below NBM, as surface high and low-
pwat airmass builds directly over PA. A milder return southwest
flow is expected Friday, as the high drifts off the Mid Atlantic
coast. GEFS 2m temp anomalies indicate highs will be several
degrees above climo. Increasing clouds are expected across the
northwest half of the forecast area Friday afternoon ahead of
an approaching cold front, with the chance of showers toward
dusk over the NW Mtns.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The cold front is progged to push southeast across PA Friday
night. However, the bulk of the large scale forcing should pass
north of the state, so any rainfall should be very light and
confined mainly to the Allegheny Plateau, where lift will be
enhanced by orographic forcing.
All medium range guidance supports an extended stretch of fair
weather Saturday through early next week, as a large surface
high builds east across the state. Slightly below normal temps
appear likely Sat night into Monday AM, then a pronounced
warming trend should commence Tuesday into Wednesday, as the
surface high slips off of the Mid Atlantic coast and a return
southwest flow develops.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Late evening update.
Upper level forcing has resulted in some showers and even
a rumble of thunder across the north and west so far.
Adjusted the western TAF sits for this activity. Will adjust
the sites to the east shortly.
Earlier discussion below.
Edge of the cold front was just west of the office here late
this afternoon, now waiting for the upper level trough to move
across later this evening. This has resulted in showers and even
some borderline thunderstorms over far western PA.
For the 00Z TAF package, will leave showers out for now, but
will adjust the fcst as needed. With the dry air in place and
loss of heating most if not all the activity to the north and
west will likely fall apart.
I also did back off on lower CIGS a bit at BFD and JST, still
forecasting MVFR CIGS late. Otherwise expecting VFR conditions
elsewhere. A bit breezy on Thursday, but not real windy, as the
the pressure gradient not that tight and the high builds in
rather quickly.
Outlook...
Fri...VFR/no sig wx.
Friday Night-Sat...Showers and MVFR conditions possible at BFD
and JST. Sfc wind gusts from 280-320 degrees 20kt. Showers less
likely to the south and east.
Sun-Mon...Brief IFR conditions possible early (07Z-13Z Monday)
at KBFD and KIPT as a result of fog/stratus, otherwise VFR
conditions.
&&
.CLIMATE...
A record high temperature of 79 degrees was set at Altoona on
Wednesday (October 23rd), breaking the record of 78 degrees set
in 2020.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Fitzgerald
AVIATION...Martin
CLIMATE...Steinbugl/NPB
Area Forecast Discussion
National Weather Service Des Moines IA
1049 PM CDT Wed Oct 23 2024
...Updated for the 06z Aviation Discussion...
.KEY MESSAGES...
- Quiet and cool tonight into tomorrow morning.
- Breezy winds followed by shower and storm chances late
tomorrow through early Friday morning. A few strong storms are
possible with hail and wind the main threat.
- Quiet and seasonal conditions through the weekend.
&&
.DISCUSSION...
Issued at 253 PM CDT Wed Oct 23 2024
After sporadic gusty winds overnight and into this morning, high
pressure has begun to set in, resulting in diminishing winds from
north to south this afternoon and evening. The cooler air mass
behind the cold front has kept temperatures in the upper 50s to low
60s this afternoon, even with completely clear skies overhead. High
pressure dominates the pattern through the evening, but quiet
conditions come to an end tomorrow surface low pressure arrives
tomorrow.
A 500 hPa shortwave trough will lift out of the plains through the
day tomorrow, translating to low pressure at the surface and
flipping winds to southerly. Initially, the tightening pressure
gradients will increase winds during the day, leading to breezy
conditions through the afternoon. With these increasing winds and
clear skies in the morning, mixing through the boundary layer will
dry out conditions at the surface, leading to a brief period of
elevated fire weather conditions in the early afternoon. However,
this system will also be bringing increasing rain chances through
the day, which will help to mitigate fire weather concerns later in
the afternoon and evening.
Two moisture streams will be associated with this wave, a pacific
stream rooted in the mid to upper levels and a gulf stream in the
lower levels. This will result in two initial areas of
precipitation, one over southern Iowa and the other further north.
However, these two streams then meet as a 50 to 60 kt LLJ ramps up
late tomorrow afternoon and into the evening. Rainfall amounts are
expected to be maximized along the nose of the LLJ, where these two
moisture streams meet and convergence is greatest. Most of the
deterministic QPF output shows this in the form of a 2 to 3 county
wide, east to west oriented band of inch or greater rainfall. Models
disagree on exact placement, but the most favored areas are
currently south of Highway 30 and east of I 35. Areas outside of
this band likely wont see nearly as high of values, generally less
than a quarter of an inch, depending on the location. It is worth
noting that models have wavered recently on precipitation placement,
so wouldnt be surprised if the system speeds up, pushing the
highest rainfall amounts and chances a bit further east again.
Beyond just the rainfall, there will be some low end severe chances
with storms in the afternoon and evening. Instability values still
look fairly marginal, but short range guidance has been sneaking a
pocket of 1000+ J/kg of MUCAPE into southern and central Iowa, which
would be sufficient to produce stronger storms. This CAPE will be
fairly shallow, and likely elevated due to a warm nose aloft that
never fully erodes. Wind fields will also have a respectable 30 to
35 kts of effective wind shear aloft, which would be enough to
produce an organized storm or two.
With storms being rooted aloft, hail and wind will be the primary
concerns, with tornadoes being unlikely. Hail will be the most
likely severe hazard, with most of the instability being above
freezing and plenty of CAPE through the hail growth zone. However,
the limiting factors will be the magnitude of the instability as a
whole and the shallow nature of the updrafts, which will reduce
residence time of any hailstones. Therefore, expecting mostly small
hail, with the chance for a few storms nearing severe hail
thresholds (inch or greater). Winds on the other hand will be a more
isolated threat and likely limited to the initial development.
Dewpoints are going to be quite dry as storms develop tomorrow
afternoon and evening, with a T/Td spread of over 20 to 30 degrees F
possible at some locations. This dry layer will be relatively
shallow (~1-2 km deep, at best), but with how dry it will be, could
certainly see a few isolated stronger gusts. SPC currently has a
marginal risk driven by the hail probabilities, which matches with
ML guidance that shows hail as the most likely severe hazard. Of
note, the HRRR neural network output has no severe hazard
probabilities being output with tomorrows storms.
A cold front then swoops in behind this system, bringing
temperatures back down to more seasonal values into the weekend. The
surface high pressure behind the wave will stick around a bit longer
than todays high pressure, keeping conditions dry and quiet through
Saturday. Winds then begin to increase steadily Sunday and into next
week as we shift towards a potentially more active pattern to start
the week. Current long range guidance is depicting a large 500 mb
trough deepening over the western CONUS and tracking east through
the plains region. Wind fields look quite strong as this occurs,
resulting in decent moisture transport and potentially some more
rainfall chances. O06Z_TAFf course, this is still just under a
week out, so will wait until we get a bit closer before getting
too excited over it!
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1049 PM CDT Wed Oct 23 2024
VFR conditions remains widespread overnight into much of
Thursday with increasing mid and high clouds by Thursday
afternoon. Showers and thunderstorms are expected to develop by
early evening Thursday impacting most TAF sites during the
evening before exiting to the east. This will likely produce
MVFR ceilings along with the potential of lightning near the TAF
sites. Have begun to trend the later portion of the TAFs toward
this scenario but with limited details at this point given the
uncertainty.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
DISCUSSION...Dodson
AVIATION...Cogil