Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/27/18
Area Forecast Discussion
National Weather Service Albany NY
1052 PM EDT Fri Oct 26 2018
.SYNOPSIS...
Precipitation overspreads eastern New York and western New
England after midnight, as a coastal low approaches the region.
Widespread rainfall and mountain snow, along with gusty winds
are expected. The precipitation will be mainly rain at lower
elevations including the Hudson and Mohawk Valleys, however some
snow will fall over higher elevations Saturday morning with
light accumulations likely along with a bit of sleet or freezing
rain possible. The precipitation will diminish to rain showers
and drizzle across all areas late Saturday and Saturday night.
Cool, unsettled weather will linger into Sunday.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1052 pm EDT...A double barrel low pressure system is
lifting northeast from the Carolina`s and OH Valley. The warm
advection pcpn has reached southeast PA and southern NJ based on
the latest local and regional radars. Some light showers have
reached north-central PA and western NY in the region of upper
level diffluence in the southwest flow aloft with the mid and
upper level trough becoming negatively tilted with the short-
wave energy upstream phasing into the coastal low. This update
continued the trend with the last few runs of the 3-km HRRR
slowing down the onset of the pcpn. The 00Z KALY sounding is
very dry below 850 hPa. It will take some time to saturate. Dry
air is in place with the retreating high offshore. Temp/dewpt
depressions look large enough that some wet snow may mix in with
wet bulb cooling between 4 and 6 am across even the Capital
Region. We may see a coating to a slushy couple tenths of an
inch before mixing with a little sleet, and then changing to
rain. We increased the amounts slightly based on the latest NAM
profiles over the eastern Catskills/eastern Adirondacks with 2-4
inches. We also think 1-4 inches is possible Sat-Sat night in
the southern Greens. We slowed the onset timing for mainly 2-4
am for the southeast Catskills and mid Hudson Valley and NW CT,
4-6 am for the Capital Region, Berkshires, Mohawk Valley, and
6-8 am for the northern tier of southern VT, the Lake George
Saratoga Region, and the southern Dacks.
The headlines remain in place in terms of the Winter Wx
Advisories and Wind Advisory tomorrow.
Previous discussion follows:
The main challenge with this forecast will be how much if any
snow or mixed precipitation will fall, and also wind potential.
Starting with the mixed precipitation potential, a rather chilly
and dry airmass covers the area this afternoon with dew points
mainly in the teens across northern NY and 20s to near 30 across
the south. Temperatures are mostly in the lower to mid 40s. High
pressure associated with this air mass will drift across
northern New England tonight moving off the coast on Saturday.
The combination of high pressure to the northeast and low
pressure moving north along the coast will favor cold air
stubbornly hanging on across much of our area into Saturday.
Model thermal profiles suggest that higher elevations will
experience a period of snow late tonight and Saturday morning
along with perhaps a few hours of a mix including some sleet and
possibly even a little icing, before the precipitation
transitions to rain then showers and drizzle Saturday afternoon.
A winter weather advisory has been issued for the Catskills,
Greens and Adirondack mountains for late tonight and Saturday
morning for up to a couple of inches of snow along with the
potential for an icy mixture of precipitation. In the Hudson
and Mohawk Valleys temperatures will be a bit warmer, and
precipitation type will be mainly rain, although a brief period
of wet snow or sleet cannot be ruled out at the onset late
tonight from the Capital District and points north.
The main focus for lift will shift north of the area later
Saturday with precipitation diminishing to rain showers and
drizzle.
For the wind, expect a band of 60 kt 850 mb easterly flow to
sweep across the area from south to north late tonight through
Saturday as the coastal lows moves north up the coast. The
strongest winds will remain decoupled from the boundary layer
but some 40 to 50 kt gusts could reach the ground over higher
elevations of the Berkshires and Greens on Saturday, along with
favored downslope areas to the west. Wind advisories have been
issued for those areas from late tonight through Saturday.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Saturday night and Sunday will feature clouds, and a few
showers mainly north and west of the Capital district in
northwest flow around low pressure spinning across northern New
England and southern Quebec. Cooler air will be filtering across
the area aloft so some higher elevations will mix with snow
showers Sunday, although little to no snow accumulation is
expected in our area after late Saturday.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
The long term forecast period will be active with multiple chances
for precipitation due to a rapidly translating shortwave trough
swinging through on Monday, followed by a quasi-stationary boundary
oriented SW-to-NE over the region for the second half of the week.
Monday and Tuesday... A shortwave trough and associated clipper-like
low will be quick on the heels of the exiting low pressure system on
Monday. This will bring some rain showers to the region with the
higher terrain of the Adirondacks, southern Vermont and eastern
Catskills seeing a chance for some snow showers. Some very light
snowfall accumulation will be possible over the mountain peaks of
the aforementioned regions. Mid-level height rises and surface high
pressure will build into the region on Tuesday keeping conditions
dry. Some guidance suggests that there could be some lake effect
precipitation over the western Mohawk Valley and Adirondacks with
westerly flow over Lake Ontario on early Tuesday but moisture looks
too limited at this time to include any PoPs. Most locations will
see partly cloudy to mostly sunny skies by the afternoon hours
Tuesday. Temperatures will be in the 40s for most locations with the
higher elevations being stuck in the 30s. Lows will be in the low
30s to low 40s.
Wednesday through Friday... The high pressure will slowly drift east
as a quasi-stationary boundary looks to set up over the region for
the second half of the week. Multiple waves of energy will likely
traverse the boundary and bring multiple rounds of precipitation to
the region. Deterministic guidance differs greatly with respect to
the placement, movement and magnitude of the boundary/precipitation
so forecast confidence is low at this time. Have kept chance PoPs in
the forecast for now, based on all the guidance suggesting
precipitation, but disagreeing on the other aforementioned
characteristics. Highs will be mild in the 40s to upper 50s with
lows in the upper 30 to mid 40s.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A low pressure system will slowly move northeast along the
coast from the Carolina`s this evening to the Chesapeake Bay
Region by daybreak, and then towards eastern New York and New
England by late Saturday morning through the afternoon.
VFR conditions will continue until about 06Z-09Z for
KPOU/KALB/KPSF/KGFL with clouds thickening and lowering ahead of
the low pressure system and its warm front. The pcpn will first
move into KPOU with light rain between 07Z-09Z. The rain may
briefly mix with some wet snow there. Further north, due to wet
bulb cooling the precipitation will likely begin as snow at
KALB/KPSF between 08Z-10Z, and later toward 10Z-12Z at KGFL.
Expect conditions to lower to low VFR/MVFR with the pcpn onset. The
thermal profiles are tricky, but a mix with some sleet and rain
may briefly occur 12Z-15Z at KALB/KPSF with snow and sleet
persisting towards KGFL closer to noon or 16Z. The column should
begin to warm with a anomalously strong low-level jet with
winds in the 1.5-2 kft AGL layer increasing to 35-45 kts. In the
mixed precipitation, expect MVFR/IFR conditions, and then
fairly widespread IFR/low MVFR cigs/vsbys in the rainfall in the
afternoon. The precipitation may taper to light rain or drizzle
at KPOU after 20Z.
Low level wind shear will be a problem shortly before daybreak,
and wind shear groups were kept in the TAFs from 09Z-13Z from
KPOU northward to KGFL, as the 1.5-2.0 kft AGL winds increase
from the east at 35-45 kts. The sfc winds will be from the east
to north/northeast at 5-10 kts during the onset time. Initially,
the winds will calm to light prior to 06Z, before they increase
towards daybreak. The north to northeast winds will increase in
the late morning into the afternoon at 10-16 kts with some
gusts in the 20-30 kt range with the higher gusts near KPSF, as
the coastal wave gets closer to the region, and some stronger
winds mix to the sfc. We removed the LLWS groups after 19Z and
20Z at KALB/KPSF respectively, but kept them going at KGFL/KPOU
until the end of the TAF cycle, as there is some uncertainty if
the better wind gusts translate to the sfc at those two
terminals.
Outlook...
Saturday Night: High Operational Impact. Definite SHRA.
Sunday: Moderate Operational Impact. Chance of SHRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: Moderate Operational Impact. Chance of SHRA.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: Low Operational Impact. Slight Chance of SHRA.
Wednesday: Moderate Operational Impact. Chance of SHRA.
&&
.FIRE WEATHER...
Dry into this evening then precipitation overspreads the area
late at night into Saturday morning. The steady precipitation
is expected to gradually taper off to showers Saturday night.
&&
.HYDROLOGY...
Dry into this evening then precipitation overspreads the area
late at night into Saturday morning. The steady precipitation
is expected to gradually taper off to showers Saturday night.
Expecting between 1 to 1 1/2 inches of QPF generally along and
south of I-90 with between 1/2 to 1 inch to the north of I-90.
The bulk of this precipitation is expected to occur Saturday
morning into the early afternoon. Mainly rain is expected with
snow generally above 1500 feet. This rainfall is not expected
to cause flooding at this time, however ponding of water will
occur, especially where storm drains are clogged by fallen
leaves. The Hudson River at Poughkeepsie could reach flood
stage Saturday morning.
Our weather will remain unsettled Sunday through Monday with
light QPF amounts expected.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Wind Advisory from 5 AM to 5 PM EDT Saturday for CTZ001.
NY...Wind Advisory from 5 AM to 5 PM EDT Saturday for NYZ054-061.
Winter Weather Advisory from 2 AM to 11 AM EDT Saturday for
NYZ047-048-051-058-063.
Winter Weather Advisory from 5 AM to 2 PM EDT Saturday for
NYZ032-033-042.
MA...Wind Advisory from 5 AM to 5 PM EDT Saturday for MAZ001-025.
VT...Wind Advisory from 5 AM to 5 PM EDT Saturday for VTZ013-014.
Winter Weather Advisory from 5 AM to 2 PM EDT Saturday for
VTZ013-014.
&&
$$
SYNOPSIS...MSE/Wasula
NEAR TERM...MSE/Wasula
SHORT TERM...MSE
LONG TERM...Cebulko
AVIATION...Wasula
FIRE WEATHER...IAA
HYDROLOGY...IAA
Area Forecast Discussion
National Weather Service La Crosse WI
1100 PM CDT Fri Oct 26 2018
.SHORT TERM...(This evening through Saturday)
Issued at 220 PM CDT Fri Oct 26 2018
An active northwest flow pattern will continue this weekend with
periodic rain chances and cloudy skies.
For tonight, an area of showers ahead of a surface trough associated
primarily with low to mid-level warm advection will impact areas
primarily near and west of the Mississippi River, weakening eastward
into Saturday morning. By afternoon, any lingering showers should
diminish leaving mostly cloudy skies with maybe some breaks in the
clouds developing from the southwest. Rainfall amounts will
generally be around a tenth of an inch or less in most areas.
Temps once again will be in the mid 40s to mid 50s.
.LONG TERM...(Saturday night through Friday)
Issued at 220 PM CDT Fri Oct 26 2018
Model agreement continues to be better with a potent upper wave
tracking from the northern plains into the southern Great Lakes
Saturday night into Sunday with the surface low tracking from ND
into northern/central WI by Sunday morning. An area of showers will
work southeast given synoptic forcing with the upper wave and a
favorable upper jet position. An enhanced heavier frontogenetical
band is expected near and northeast of the low track. Right now,
this looks to be across portions of northern into central WI, where
rain amounts of up to around half an inch are possible. Outside this
band, amounts will be lighter, and current trends favor areas
generally along and east of the Mississippi River for the higher
rain chances. This system quickly pushes southeast of the area on
Sunday with drying conditions. Some guidance keeps a few showers
around into the afternoon across central WI along the periphery
of the cyclonic flow with clearing from the west late in the day.
With a more eastern track of the low favored, much of the area
will get into a period of gustier winds behind the low on Sunday.
925 mb winds are forecast in the 30-40 kt range, with 3-hr
pressure rises of 3-4 mb and along with low- level cold advection.
Winds look to be sub- advisory at this point, but likely will
gust above 30 mph for a time on Sunday.
The flow remains quite progressive, with ridging building into the
area on Monday. With the surface high already to the southeast of
the area on Monday afternoon gradient winds will pick up from the
south. This should boost temps up into the 50s at least, but these
type of days have generally been over performing over the past few
weeks, so wouldn`t be surprised to see some 60+ degree highs.
By Tuesday an upper trough will move into the Upper Midwest dragging
a cold front through the area. Model guidance suggests a quick
frontogenetical band of rain as the system sweeps through, but
differ on whether the band organizes over or east of the area.
Tuesday still should be mild, again with some 60s not out of the
question, with breezy westerly winds ahead of the lower 850 mb
temps.
For mid to late week, the mean longwave trough will be anchored over
the central US. At this point, guidance favors dry weather for
Halloween with high pressure. The 26.12Z GFS/ECMWF indicate an
embedded shortwave trough and associated surface cyclone lifting up
towards the mid-Mississippi Valley or Ohio Valley later in the
week, but it`s too early to have a high degree of confidence in
this scenario out given the degree of model spread and time range.
Under the upper trough, temps will cool down with highs mainly in
the 40s by late week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday evening)
Issued at 1100 PM CDT Fri Oct 26 2018
Active northwest flow a loft will keep the area under mostly cloudy
(mvfr) conditions with periodic showers. Higher rain threat sat
night into sun.
Cigs: mostly MVFR expected through Sunday. Models look a bit more
optimistic with bringing a period of vfr (to sct) conditions from
late Sat afternoon into the evening - esp the RAP and GFS. NAM
remains more pessimistic, esp where KLSE is concerned. Going to lean
the forecast toward a few hour break for the moment, with the
anticipation that MVFR returns late Sat night as another shortwave
trough moves through.
WX/vsby: showers continue to develop around a northwest-southeast
running sfc boundary and upper level shortwave at late evening, and
should linger into the early/mid morning hours of Sat - albeit with
a diminishing trend. Don`t expect much vsby impacts with minimal
accums.
Another round of showers moves in sat evening, persisting into
Sunday morning.
Winds: mostly southeast to variable and fairly light, holding under
10 kts in Sat night. Tightening pressure gradient post the Sat night
system will lead to an increase in winds for Sunday - strong/gusty.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...JM
LONG TERM...JM
AVIATION...Rieck
Area Forecast Discussion
National Weather Service Grand Forks ND
947 PM CDT Fri Oct 26 2018
.UPDATE...
Issued at 947 PM CDT Fri Oct 26 2018
Fog is an issue again tonight, with some localized fog in the
Devils Lake area becoming more widespread and dense during the
past few hours. Devils Lake Basin and parts of the northern Red
River Valley have been down to 1/4 mile or less at times, and web
cams look poor in areas where there is enough ambient light or
headlights to see something. None of the models have a good handle
on this particular fog area, although the RAP is somewhat close.
In theory the west winds moving into the Devils Lake basin during
the next few hours should improve things. Put out a short-ish
dense fog advisory for the Devils Lake Basin and northern RRV,
with possibility of cancelling the western portions early if
needed.
Further south, the KGFK and KFAR airports are starting to drop in
visibility, although the KGFK tower is reporting visibility above
the surface is fine and web cams are pretty good still. Think fog
is shallow and localized at the moment. Think that fog could
become more widespread in the next few hours, but am uncertain yet
over which area and how dense. Will hold off on any dense fog
advisory for this area yet but will adjust and add if needed.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 311 PM CDT Fri Oct 26 2018
The thickest clouds are now along and east of the Red River, with
some breaks showing up to the west. Drizzle and very light rain
are low level features which are not picked up well by the radars,
but surface observations show a good number of stations east of
the Red River reporting light pcpn. This light pcpn and cloud
cover will likely linger tonight east of the Red River. To the
west, the main question is probably fog formation again. With
clearing, low winds, the recent rain, and already close temp/dew
point spreads, think fog will reform again along and east of the
Red River Valley. Not sure how low visibilities will get, but that
can be monitored. There will still be a few breaks in the clouds
on Saturday, but another system will begin moving in, especially
by later morning into the afternoon. Again, this will not be a big
rain producer, but more light nuisance rain again.
.LONG TERM...(Saturday night through Friday)
Issued at 311 PM CDT Fri Oct 26 2018
The progressive upper pattern continues through the forecast period
with a series of small short wave troughs moving through largely
northwest flow aloft. This will promote periodic chances for light
rain and snow. The first wave will be passing through Saturday night
bringing rain showers and gusty northwest winds behind a cold front.
Gusts could exceed 40 mph in southeast North Dakota overnight
Saturday into early Sunday given strong surface pressure rises over
a relatively short amount of time. Rain showers have the chance of
coinciding with leading edge of strongest winds which could help
transfer higher winds in the 925-800 mb layer towards the surface.
Winds will be less outside of southeast North Dakota. Wind and rain
end by midday Saturday with mild temperatures reaching into the
upper 40s to mid 50s.
Dry conditions last late Saturday through Sunday until another wave
moves through from the west bringing the chance for light snow
Monday morning turning to all rain by midday. Another breezy day may
be in store behind this wave`s cold front late Monday into Tuesday.
Mid to late next week hold light precipitation chances with a
gradual cooling trend as flow becomes more northerly and a pocket of
cooler air moves near the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 656 PM CDT Fri Oct 26 2018
Fog has already developed at KDVL, near the lake which none of the
models have a very good handle on at this point. Have that
continuing for a while longer this evening before some improvement
as winds shift around. KBJI remains 2SM with -RA/-DZ and that will
continue for a few more hours. The central airports are mostly
MVFR although KGFK started to scatter out just as TAFs were going
out. Think there will be a brief period of VFR this evening at
KFAR and KGFK, but then fog and stratus build back towards the Red
River. Have most of the TAF sites going down to 1 or 2SM for a
while during the early morning hours. There is the potential for
greater density but not sure exactly where at this point and will
reevaluate for the 06Z TAFs. Some improvement to MVFR and then VFR
by tomorrow. Winds will be variable direction but mostly below 10
kts.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Dense Fog Advisory until 4 AM CDT Saturday for NDZ006>008-
014>016-024-026-028-054.
MN...Dense Fog Advisory until 4 AM CDT Saturday for MNZ004-007.
&&
$$
UPDATE...JR
SHORT TERM...Godon
LONG TERM...CJ
AVIATION...JR
Area Forecast Discussion
National Weather Service Lincoln IL
905 PM CDT Fri Oct 26 2018
.UPDATE...
Issued at 905 PM CDT Fri Oct 26 2018
A lingering area of drizzle will affect areas east of I-55
through 1 am or so, as the upper level trough axis shifts east of
Illinois. Rainfall amounts will remain light, but wet conditions
will still affect any evening outdoor plans. NW winds will
generally remain light, but chilly and damp conditions will be
the rule for this Fall evening. Mostly cloudy conditions will
continue through tomorrow morning in most of central IL. That will
help stabilize the low temperatures in the lower 40s, or about 3-5
degrees below current temps.
Update this evening was mainly to the PoP/weather grids to account
for the slower departure of the rain/drizzle. Otherwise, the
remainder of the forecast looks on track.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 304 PM CDT Fri Oct 26 2018
Deep h5 wave over the Midwest this afternoon is keeping low clouds
and persistent showers through the morning and into the afternoon
hours. The upper trough is widening more than actually propagating
out to the east this afternoon, prolonging the low cigs and
showers a little longer than prev forecast. Overcast skies are
expected through the overnight, limiting the min temps to the low
40s, even with a northerly component to the winds persisting. In
contrast to the trough over the eastern half of the country, the
slight ridging over the western half of the country will assist a
slow warm up just to the west. The forecast has a bit of
variability in temperatures with the northwesterly flow giving way
to influence of the warmer air from the west...starting with
tomorrow. The cyclonic flow aloft lingers long enough to keep the
first half of tomorrow cloudy before some drier air to the west
works into the region, clearing from west to east in the
afternoon. The western border of IL may approach the mid 60s,
while the eastern border may only see the mid 50s.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 304 PM CDT Fri Oct 26 2018
Sunday will see a bit of that warmer air from the west with a
brief weak ridging in btwn the exiting mid level low and
reinforcing wave. Sunday temps will climb into the low to mid
60s until displaced by a wave approaching the night before spreads
a quick chance for precip early Sunday morning into midday. Monday
will be dry at this point, with temperatures very close to
seasonal normals for the end of October. A storm system moving
across southern Canada and dropping into the Great Lakes in the
first half of the week will pull a front into Central IL overnight
Monday into Tuesday. The system is evolving quite differently at
500 mb in the ECMWF and the GFS. The GFS is actually faster with
the northern stream low, and the initial onset of the precip, but
lags the front considerably, tying it to another southern stream
wave lagging back over the SW. The ECMWF is slower with the parent
low, phasing in the southern stream into one trough, moving the
front through the FA quicker, and not lingering the precip as
long. At this point, the blended forecast is a prolonged pd of
precip from overnight Monday night into early Thursday morning.
With this longer duration event, cold air has the potential to
move in behind slow moving precip, resulting in a possible ra/sn
mix after midnight Wed night NW of the IL River.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 648 PM CDT Fri Oct 26 2018
Lingering MVFR or low VFR clouds and drizzle will affect the
terminal sites for the first 3-4 hours of the 00z TAFs. The upper
level trough axis will pull away to the east tonight, helping to
bring an end to the precipitation, but low level moisture will
linger through the morning on Saturday. Enough drying and mixing
of dry mid-level air will help clouds to clear out Saturday
afternoon, as NW flow becomes dominant behind the departing
trough. HRRR is showing a few bands of IFR clouds late tonight
around sunrise, so a brief tempo was included to account for those
potential cloud ceilings.
Winds will generally be light from the north overnight, and light
NW tomorrow.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...HJS
LONG TERM...HJS
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Indianapolis IN
1152 PM EDT Fri Oct 26 2018
.UPDATE...
The AVIATION Section has been updated below.
&&
.SYNOPSIS...
Issued at 242 PM EDT Fri Oct 26 2018
Low pressure in place over Kentucky and Tennessee is expected to
drift northeast toward Appalachia tonight. The bulk of rain
showers should come to an end as the low departs...but some
lingering clouds and lower level moisture may result in some very
light showers tonight and early on Saturday.
A weak area of high pressure will move across the area on Saturday
afternoon and Saturday night. This should lead to mainly dry and
cool weather then.
Another quick moving low pressure system and upper level weather
disturbance is expected to push across Central Indiana on Sunday.
This will once again lead to chances for showers.
High pressure and dry weather is expected to return for Sunday
night and the start of the work week. More rain will be possible
on Tuesday and Wednesday as another low pressure system arrives.
&&
.NEAR TERM /Tonight/...
Issued at 848 PM EDT Fri Oct 26 2018
Radar loop and short term model data suggest organized lift will
be pushing off to the east of the forecast area over the next
couple of hours, so should continue to see a diminishing trend in
the precipitation over the rest of the evening. However, the upper
trough will linger over the area most of the night. As a result,
may see some patchy light rain or drizzle, mainly over the
eastern zones, most of the night.
Temperatures look to hold about where they are for the rest of the
night.
Previous discussion follows.
Surface analysis shows low pressure in place across Kentucky and
Tennessee. Cyclonic northeast flow was in place across Indiana.
GOES16 showed a large cloud shield in place across Indiana. Radar
shows numerous rain showers across the forecast area
...drifting northeast. Water vapor showed an upper trough near
southern Illinois...pushing northeast toward Indiana.
The GFS and NAM suggest the upper trough axis will slowly push
across the forecast area tonight. Best forcing associated with the
trough axis looks to exit the forecast area by 00z-03z.
However...forecast soundings and time height sections continue to
suggest good lower and middle level moisture available through the
night. HRRR suggests the bulk of the precipitation should be
limited to the eastern 1/3rd of the forecast area by 00Z...and
pretty much over OH by 03Z. This seems reasonable given the
expected progression of the upper trough providing the forcing and
the departure of the surface low to the east. Will continue to
keep some pops in the forecast...particularly across the east
during the first few hours of the evening. Broad cyclonic flow
will continue to remain in place across Indiana along with
plentiful lower level moisture. Thus an isolated light shower or
sprinkle cannot be ruled out...but amounts and coverage will be
minimal. Thus will trend to lower pops overnight.
Given the expected clouds...will trend overnight lows at or above
the forecast builder blends.
&&
.SHORT TERM /Saturday Through Monday/...
Issued at 242 PM EDT Fri Oct 26 2018
The quick moving upper trough will exit Central Indiana on
Saturday...allowing weak ridging to build across Indiana aloft.
Meanwhile...time height continue to suggest saturated lower and
middle levels as the lower level flow remains predominately
cyclonic...influenced by the low over the middle Atlantic States.
Thus with strong forcing out of the area...organized rain is not
expected...but given the lower level moisture and flow...an
isolated very light shower cannot be ruled out on Saturday.
Chances for shower will continue to diminish on Saturday night as
the low and upper wave continue to exit east and weak ridging
develops across the area. Forecast soundings appear to
agree...showing some drying within the mid and upper levels. Thus
will trend toward a dry forecast on Saturday night forecast
builder willing.
GFS and NAM suggest a quick moving upper wave and an associated
surface low pressure system pushing out of the northern plains and
crossing Central Indiana on Sunday morning. Forecast soundings
show a good return of moisture as these features pass on Sunday.
With ample forcing expected...another round of rain showers will
be expected. Best chances will be across the north and east parts
of the forecast area where the proximity to the forcing will be
best. Will use highest pops here and taper lower to the southwest
where dynamics will be less. As the forcing quickly departs in the
afternoon...pops will decrease as the day progresses.
Dry weather will be expected on Sunday night and Monday as high
pressure and ridging aloft builds across Indiana and Illinois.
Forecast soundings again trend toward a dry column again on
Sunday and Monday. Will stick close the forecast builder blends.
&&
.LONG TERM /Monday night through Friday/...
Issued at 311 PM EDT Fri Oct 26 2018
Dry weather will be in place to start the long term as high
pressure moves across central Indiana. On Tuesday, though, the
next low pressure system will approach the area and bring chances
for rain. There are some differences on timing of the system right
now, with the GFS being faster with the arrival and ECMWF slower
and ensembles showing similar differences. There is some
indication that the front could get hung up nearby, and this would
keep rain in the forecast through at least the day on Thursday.
May need to monitor Tuesday into Wednesday for a thunder inclusion
at a later issuance, but right now too low of confidence of
instability getting this far north. Also of note, some hinting in
the operational solutions of potential for heavy rainfall Tuesday
afternoon into Wednesday across the southern counties. Not a
consistent signal so at this point just need to continue to
monitor. Temperatures should run below normal through much of the
long term, with the exception of Tuesday which could get warmer
than normal and see highs in the mid 60s.
&&
.AVIATION /Discussion for the 270600Z TAFS/...
Issued at 1152 PM EDT Fri Oct 26 2018
Ceilings generally 030-045 expected at the terminals through the
midday hours of Saturday for the most part. Short term model data
suggest these lower ceilings may temporarily scatter out later
tonight into the mid morning hours of Saturday, particularly at
KHUF/KLAF.
Surface winds 330-350 degrees at 6-9 kts overnight will become
310-330 degrees at 9-13 kts by midday Saturday. Occasional surface
gusts around 18 kts possible by midday as well.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Puma
NEAR TERM...Puma/JAS
SHORT TERM...Puma
LONG TERM....CP
AVIATION...JAS
Area Forecast Discussion
National Weather Service Key West FL
946 PM EDT Fri Oct 26 2018
.DISCUSSION...In the middle and upper levels( 700-200 mb), latest
available GOES-R satellite imagery overlaid with model streamline
analysis as of 900 pm, detail the sharpening axis of a positively
tilted full latitudinal trough presently extending from Northern
Lake Michigan south southwest to the Edwards Plateau of Texas.
The center of a deep and warm core anticyclone is centered over
the South Central Caribbean Sea. South Florida and the Keys,
however are becoming increasingly underneath lowering mid-level
heights on the outer flank of the aforementioned deep troughing.
At the surface and in the lower to mid levels(Surface to 700 mb),
latest available GOES-R satellite imagery overlaid with marine
and land surface observations and surface analysis, depict an area
of low pressure near Savannah which presently is trailing a cold
front southwest to the Central Gulf of Mexico, or several hundred
miles west of Key West. As a result, this evenings 00Z sounding
illustrates a drying lower to mid troposphere with columnar PWAT
only at 1.07 inches and a gentle to moderate westerly flow from
the surface to 850 mb, then freshening above that up to 600 mb
where a moist patch of altocumulus exists.
.CURRENTLY...As of 900 pm, radar only detects a few precip-free
boundaries on either side of the Florida Keys attm. skies are
partly cloudy across the islands and surrounding waters, owing
mostly to some coverage of middle level clouds aoa FL130-170.
Temperatures across the islands are in the lower 80s with
dewpoints in the lower 70s. C-man stations along the Florida Reed
are recording southwest to west winds at 10 to 15 knots and at
Smith Shoal light. Island platforms are recording southwest to
west winds near 10 mph.
.SHORT TERM...Overnight, the surface front, now located about 150
miles west of Key West, will continue to move east overnight, and
move across the Keys during Saturday. This will occur as low
pressure develops along the Middle Atlantic Coast and then
intensifies during Saturday, reaching Long Island by sunset.
Ahead of this feature, weak low level confluence and a lack of
upper support, will only support development of isolated showers
along some boundaries. HRRR and Wrf models indicate best chances
for showers, albeit low, remains tomorrow morning. Surface winds
will remain gentle tonight and through the morning, as there is
very little 1000-850 thickness advection over very warm Gulf
waters upstream of the Keys. Slight cold thickness advection will
hold off until the afternoon hours, when local breezes veer around
to northwest to north and increase. No changes to the ongoing
forecast on this cycle.
&&
.MARINE...Gentle to moderate west breezes will become gentle west
to northwest breezes by sunrise, becoming northwest and moderate
thereafter. No headlines or advisories overnight and Saturday.
&&
.AVIATION...
VFR conditions expected to prevail at both island terminals. Drier
low level air will preclude the need for VCSH in the short term
(first 12 hours), with a bit more uncertainty in the long term (last
12 hours) as a cold front approaches the area. Opted to leave VCSH
out of the TAF for now given uncertainty. Relatively light westerly
winds, veering to northwesterly.
&&
.CLIMATE...
On this date in 2015, the daily record warm low temperature of 80
degrees was last recorded. Assuming the temperature does not fall
below 81 degrees by midnight, we are on track to break the record.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...Futterman
Aviation/Nowcasts....WLC
Upper Air/Data Collection......SD
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