Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/01/23
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1025 PM EDT Sun Apr 30 2023
.SYNOPSIS...
Periods of rain, heavy at times, will continue through tonight
before tapering off from south to north toward daybreak Monday.
It will remain cool and showery for much of the upcoming week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Flood Watch in effect through 2 am for Ulster and Greene
Counties...
Wind Advisory has been cancelled...
.UPDATE...As of 1025 PM EDT, an upper-level low continues to
slowly track eastward across the Great Lakes while a potent,
upper-level shortwave rotates around the main low across the
northeast. A rather seasonably strong area of low pressure (986
hPa per latest RAP analysis) is tracking northward toward Long
Island. An inverted trough is located just to the west of our
area closer to the I-81 corridor. Overall, strong forcing from
all of these features is resulting in widespread rainfall, which
will continue through much of the overnight hours. A convective
band of showers and thunderstorms is lifting northward and
approaching Long Island and will then move into southern areas
around and shortly after midnight. Here, rainfall rates may
increase to 0.50 to 1.00 inches per hour for a short time and
may result in some localized minor flooding in urban and poor
drainage areas. Despite a decrease in precipitation intensity,
we have extended the current flood advisory for portions of the
mid-Hudson Valley and eastern Catskills as we anticipate this
convective band to impact the area shortly, which could increase
minor flooding problems in the area once again. We will also
keep the flood watch as is until it expires at 2 am, though,
areas across Dutchess and Litchfield counties should be on alert
for some possible minor flooding with the approaching
convective band. Elsewhere, we still expect this rainfall to
lead to little if any hydrological issues.
Wind speeds across portions of western New England and the
Taconics of eastern New York have generally been in the 30 to 40
mph range. With the nose of the low-level jet now lifting
northward out of our area, wind speeds are expected to slowly
trend downward through the remainder of the night. As we have
not observed any wind advisory criteria winds (46 mph or
greater), we have cancelled the wind advisory an hour earlier
than its original expiration time.
Precipitation will begin to taper off from south to north during
the overnight and early morning hours on Monday. With the clouds
and the rain, temperatures will hold fairly steady tonight in
the 40s with some upper 30s across some of the higher terrain.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Monday, subsidence behind the shortwave trough rapidly
translating north of the area, combined with midlevel dry air,
should result in a dry start to the day. However, the
combination of midlevel cold advection and diurnal heating
should allow showers to quickly develop during the afternoon
hours as shallow instability develops. The most widespread
showers will be located north of I-88 and west of I-87 where the
midlevel cold pool will be strongest (700 mb temps falling to
minus-10C). Equilibrium levels will be rather high at around 15
kft, so isolated thunderstorms producing graupel or small hail
will be possible. Highs are expected to range from the upper 40s
to low 60s. The showers and isolated storms are expected to
wane Monday evening, but coverage will likely increase again
late Monday night as a shortwave trough pinwheels into the area
around the upper low wobbling around just north of Lake Ontario.
Lows Monday night should range from the mid-30s to mid-40s with
a few snowflakes possible in the higher elevations.
Tuesday, the upper low will remain rather stationary in the
vicinity of the local area thanks to an evolving omega block
over the CONUS. Associated midlevel cold pool combined with
diurnal heating will result in numerous to widespread showers
and isolated storms, with coverage likely better than Monday
over most areas. It should be cooler than Monday with highs only
reaching the mid-40s to mid-50s. Scattered rain and high-
terrain snow showers will continue Tuesday night with lows in
the low 30s to low 40s. Little to no accumulation is expected.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Upper cutoff low and associated midlevel cold pool are expected
to remain over the local area at least Wed/Thu thanks to an
omega block over most of the CONUS, keeping temps on the cool
side and showers prevalent. Numerous to widespread showers
expected again on Wednesday, especially during the afternoon and
evening as weak diurnal instability develops. 700 mb temps
continue to average around minus-10C, which is -1 to -2 standard
deviations. The midlevels may warm slightly Thursday as the
core of the cutoff low shifts east, so showers may be a bit less
widespread compared with Wednesday, but scattered to numerous
showers can still be expected. Highs both days are likely to be
in the 40s and 50s.
For Friday into next weekend, there are some signals that the
blocky pattern breaks down somewhat, with higher midlevel
heights gradually building in. There is uncertainty as to how
quickly this happens, however. At least isolated to widely
scattered showers remain possible Fri/Sat, and will trend the
forecast mainly dry by Sun. Temps will increase as well,
possibly back to near seasonal normals over the weekend with
highs mainly in the 50s and 60s.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Through 00z Tuesday...While there are a few pockets of VFR
vsbys/cigs this evening, seeing mostly MVFR and some IFR
conditions. Expecting conditions to deteriorate over the next
few hours as additional moderate to heavy rain moves in from the
south. GFL may stay low-end MVFR, but expecting IFR vsbys/cigs
with moderate to heavy rain at ALB/POU/PSF from late this
evening through around 8- 10z tomorrow morning. Rain tapers to
showers late tonight/early tomorrow morning, and improvement
back to VFR conditions is expected after 12z tomorrow at
ALB/POU/GFL and after 15z at PSF. VFR conditions prevail through
the rest of the day, although additional scattered "pop-up"
showers are expected tomorrow afternoon. Will use VCSH and prob
30 groups at all TAF sites to highlight brief MVFR vsby and
possibly cig restrictions in these showers.
Winds will be at 5-10 kt from the east/northeast tonight, with
some gusts of 15-20 kt possible. Between 6-9z, winds switch
abruptly to the west/southwest behind a frontal passage. Note
that there is some uncertainty in the exact timing of the wind
switch, and it is possible this wind shift could occur an hour
or two earlier than the current TAFs indicate. Tomorrow morning,
winds will be at around 10 kt with some gusts to 20 kt from the
southwest. Winds become more southerly tomorrow afternoon still
at around 10 kt with some 20 kt gusts. Included low-level wind
shear at POU and PSF this evening with a strong low-level jet
overhead. ALB and GFL will come close, but likely fall just
short of LLWS criteria. However, at these sites winds between
2000-3000 ft will likely be at 40-50 kt from the east/southeast
this evening through 3-4z before diminishing afterwards.
Outlook...
Monday Night: Moderate Operational Impact. Likely SHRA...TSRA.
Tuesday: High Operational Impact. Definite SHRA...TSRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: High Operational Impact. Definite SHRA.
Wednesday Night: Moderate Operational Impact. Chance of SHRA.
Thursday: Moderate Operational Impact. Chance of SHRA.
Thursday Night: Low Operational Impact. Slight Chance of SHRA.
Friday: Low Operational Impact. Slight Chance of SHRA.
&&
.HYDROLOGY...
A stronger storm system will bring moderate to possibly heavy
rainfall through tonight. It appears this next round will bring
0.75 to 2.00 inches of rain in most areas, with higher amounts
of 1.50 to 3.00 inches over easterly aspects of the eastern
Catskills and southern Greens. Furthermore, elevated
instability will cause brief heavy downpours this evening. This
rainfall could result in minor urban and poor drainage flooding.
Most rivers are forecast to crest below flood stage on Monday,
but a few spots along the Schroon, West Canada, Schoharie,
Esopus, Rondout, and Housatonic may get close to minor flood
stage. A Flood Watch was issued for Greene and Ulster Counties
to account for the heavy upslope rainfall in the Catskills and
rises on the creeks and streams draining the Catskills. This
area was preconditioned a bit by 1-1.5 inches of rain over the
last 48 hours. Overall, do not expect this to be a major or
widespread flood event, but at least some flooding is possible,
especially in small creeks and streams, urban areas, and typical
low lying spots.
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...None.
NY...Flood Watch until 2 AM EDT Monday for NYZ058-059-063-064.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Thompson/Rathbun
NEAR TERM...Thompson/Rathbun
SHORT TERM...Thompson
LONG TERM...Thompson
AVIATION...Main
HYDROLOGY...Thompson
Area Forecast Discussion
National Weather Service Cheyenne WY
530 PM MDT Sun Apr 30 2023
.SHORT TERM...(This evening through Monday)
Issued at 300 PM MDT Sun Apr 30 2023
Forecast challenges deal with precip chances the next couple days.
Currently...surface low in central Colorado with a stationary
front extending north into Albany County near Laramie...north
northwest to Casper and then northwest into western Montana this
afternoon. Winds northeast east of the front...westerly to the
west of the front. Surface ridge of high pressure extends south
out of Saskatchewan Canada...south to western South Dakota...all
the way down to the Oklahoma/Texas Panhandle area. Radar has been
PPINE so far this afternoon with a few mid and upper level clouds.
Most areas are clear.
RAP and HRRR mesoscale simulated radar continues to remain dry
this afternoon. Went ahead and removed PoPs from the forecast
this afternoon and early evening.
Real nice day Monday across the CWA as upper ridge axis begins to
move into Carbon County. Seeing 3 to 6C warming of 700mb
temperatures over the next 24 hours...so afternoon highs Monday
likely to be several degrees warmer over todays highs.
Ridge axis right over eastern Wyoming Tuesday morning...with
afternoon highs in the mid 70s in the Panhandle and near 70 west
of the Laramie Range. By Tuesday afternoon...ridge axis forecast
to be near the Nebraska Panhandle. GFS/ECMWF/NAM/SREF guidance all
in agreement with showers developing over the western half of the
CWA west of the Laramie Range. So continued high end chance PoPs
from Cheyenne to Elk Mountain Tuesday afternoon.
.LONG TERM...(Monday night through Sunday)
Issued at 330 PM MDT Sun Apr 30 2023
As the calendar flips to May, the weather looks likely to reflect
the changing seasons. The primary focus of this outlook is a period
of unsettled weather increasingly likely for Thursday through
Saturday, that will bring daily chances for showers and
thunderstorms.
The synoptic pattern this week will be dominated by an omega-block,
with a narrow but amplified ridge over the Rockies/central Plains
sandwiched in by two stubborn upper level lows meandering near each
coast. Expect warm temperatures underneath the ridge, with Wednesday
likely the warmest day of the week. GEFS mean 700-mb temperatures
maximize around 00z Thursday at about +8C likely supporting
widespread 70s to 80s across the area. Wednesday is likely to
continue the pattern of isolated afternoon convection, but this is
not expected to be widespread or organized. By Thursday, however,
models continue to show a weak point in the middle of the ridge over
our area developing. This will allow a series of vort-maxes rotating
around the west coast upper level low to push through the area from
southwest to northeast. Simultaneously, the break in the ridge may
allow deeper southeasterly flow to develop on the southwest flank of
the lobe of the ridge left to our north over Canada. The result of
this will be fairly deep moisture advection through the day on
Thursday into the high plains. GEFS mean dewpoints at KBFF exceed
50F by 00z Friday. Moreover, the NAEFS mean and ECWMF ensemble mean
precipitable water and 700-mb specific humidity values both
approach or exceed the 99th percentile of climatology. With
plentiful moisture present, all we would need is some lift to get
precipitation going. One piece will come in the form of the
positive vorticity advection from the vort-max aloft.
Additionally, the GFS depicts a mid-level convergence boundary
developing between southwest flow over the mountains and southeast
flow over the high plains, producing significant frontogenesis
and vertical motion in the 700 to 500-mb layer. Modest instability
will also be present, indicating the possibility for
thunderstorms. The ECMWF is not as aggressive with the convergence
boundary and thus still produces numerous showers and storms, but
with a bit less QPF.
Additional vorticity lobes moving through are likely to additional
rounds of scattered to widespread showers and thunderstorms on
Friday. Finally, models are in fairly good agreement of a more
significant shortwave passing through on Saturday. This activity is
reflected in the forecast with widespread PoPs in the 40 to 60%
range each afternoon and evening with rounds of precipitation
developing over the higher terrain and moving off to the northeast
through the overnight. This overall pattern has fairly strong
ensemble support, with almost all members showing widespread
precipitation. The highest confidence in higher rainfall totals is
further off to the east, whereas Carbon county will likely receive
less. The GEFS 50th percentile total QPF exceeds 1.25" at KCYS by
Saturday evening, while the ECMWF ensemble 50th percentile is a
little more modest at 0.75". Observed precipitation will likely
depend on mesoscale features, so may be quite a bit more variable
than what is depicted in an ensemble mean, but this is where the
confidence is right now at several days lead time. Temperatures look
to cool down a bit for Thursday-Sunday as model mean 700-mb
temperatures drop to the +2 to +4C range. As far as the severe
potential goes, we will have modest instability and some vertical
wind shear, but parameters look on the low end for what could
produced organized severe convection. However, we still are likely
to see isolated to scattered strong convection with gusty winds and
small hail. It`s a little early to be going into the details on
storm type and threat though, so this will be ironed out in the
coming days. We will also need to closely monitor snow levels with
this event. Substantial snowpack remains as low as 7500 ft in some
areas, and current best estimate snow levels for the late week
precipitation are around 9000 ft or higher. Warm rain on snow could
lead to accelerated runoff and the potential for flooding. Thus,
the main takeaway here is to expect a period of unsettled weather
from Thursday through Saturday, with scattered to numerous showers
and thunderstorms likely each afternoon extending into the
overnight, though details on rainfall totals, severe potential,
and flood potential remain uncertain.
&&
.AVIATION...(For the 00Z TAFS through Monday afternoon)
Issued at 530 PM MDT Sun Apr 30 2023
A weak convergence boundary will remain near the Laramie Range this
evening before weakening tonight. Shower activity associated with
this boundary has mainly been confined to the mountains and even
there has been short-lived. Expect SCT to BKN skies around 6k feet
agl this evening to dissipate.
HAZARDS/WEATHER TRENDS: VFR conditions are expected with probability
of fog or low CIGS near zero percent tonight and into Monday
morning.
&&
.FIRE WEATHER...
Issued at 300 PM MDT Sun Apr 30 2023
Stationary front currently lays from Laramie to just south of
Casper...west northwest to Riverton and then north into western
Montana this afternoon. East of this front...northeasterly winds
are common...while west...westerly winds prevail. Minimal fire
weather conditions with above critical afternoon humidity and
light winds this afternoon. Warmer Monday as upper high pressure
builds into the area from the west. Again...afternoon humidity
expected to stay above critical levels. By Tuesday...upper ridge
moves east into the Panhandle with chances for showers and
thunderstorms developing along and west of the Laramie Range. May
see critical afternoon humidity Wednesday...but strong winds are
not expected.
&&
.HYDROLOGY...
Issued at 310 AM MDT Sun Apr 30 2023
Warmer temperatures this week will produce snowmelt runoff into the
Little Snake River and Upper North Platte River basins. The CO Basin
RFC is still forecasting the Little Snake River to climb above action
stage near Dixon by the middle of next week. We will also need to keep
an eye on snow levels later this week as the closed low approaches
from the southwest. If snow level stays above 9000 ft we may be looking
at the potential for rain on snow, which may ripen the snow pack more
or cause faster snowmelt.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...MN
AVIATION...TJT
FIRE WEATHER...GCC
HYDROLOGY...MJ
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
605 PM CDT Sun Apr 30 2023
.Discussion...
Issued at 259 PM CDT SUN APR 30 2023
Key Messages:
- Breezy Through Monday
- Seasonable Temperatures
- Next Precipitation Chances: Thursday/Friday
Discussion:
500mb pattern currently dominated by a closed-low system over the
Central Great Lakes Region with open short-wave trough axis through
the southeast Atlantic Coast. An amplified ridge axis currently sits
over the Intermountain West. This has left our forecast area in mid
to upper-level northwesterly flow, forcing the cold front that
passed through last night well south of the Ozarks. At the surface,
low pressure is directly underneath the closed H5 low over the
Central Great Lakes. There is a stronger high pressure over the
Canadian Prairie Provinces with inverted ridge extending into the
Central High Plains. With stronger AVA and subsidence over the
central CONUS, would anticipate for the surface high pressure to
strengthen over the next 12 to 18 hours, and with the exiting low
over the Great Lakes Region should maintain a stronger pressure
gradient across the region. This along with stronger mixing this
afternoon will continue gusty northwesterly winds up to around 35
kts. Locally higher gusts are possible, especially in northeastern
portions of the forecast area where winds at the top of mixed layer
are progged around 37 kts. This afternoon, GOES 16 satellite imagery
has shown the development of a cumulus field across most of the
forecast area. With steeper boundary layer lapse rates and weak lift
still on the backside of cyclonic flow, expect this to continue
through the afternoon and dissipate after peak insolation is lost.
The boundary layer is quite dry after yesterday`s FROPA, and will
prevent any precipitation that may try to form from the cumulus
field. For Monday, subsidence downstream from the H5 ridge axis will
continue to keep skies mostly clear. Additional clouds are possible
in our far east and northeast which may be on the very edge of the
cyclonic flow from the closed-low system to the east. Most of the
moisture though is being held east of that system, which should
inhibit broken or overcast skies. Another breezy day may be in store
for eastern Kansas into east-central Missouri with strong gradient
flow still in play, and boundary layer mixing through afternoon
again. Current RAP soundings indicate 30 to 35 kts toward the top of
the mixed layer again, especially east of Interstate 35.
Temperatures will be in the lower to mid 60s. Cooler temperatures
possible in the far northeast if cloud cover from central Illinois
drops southwestward into our area.
A quick note on fire weather conditions for Monday: RH values may
drop below 30 percent in northwest Missouri with wind gusts 20 to 25
MPH. Wind gusts above 30 MPH are favored more for northeast
Missouri, where temperatures should be cooler and not nearly as dry.
Therefore, no fire weather headlines were issued, but will need to
watch the winds closely in northwest Missouri. An increase in winds
could increase fire weather concerns in northwest Missouri on Monday.
Tuesday and Wednesday, a PV anomaly over the eastern Pacific
develops a strong closed-low at H5 over the west coast and results
in an Omega Block pattern for most of the CONUS, as the closed-low
system currently east of the area slides into the eastern Great
Lakes Region. The back-edge of the cyclonic flow should just exit
out of our area. Meanwhile, low-level flow across the central CONUS
turns southerly in response to the PV anomaly over the west coast,
and helps to amplify the H5 ridge across the central CONUS. While we
will not be in a predominant WAA regime, the nose of the warm air
will attempt to push up against our forecast area. With the mid to
upper-level flow northwesterly and AVA downstream from the ridge
axis, skies should remain clear enough to allow stronger isolation
on Tuesday and Wednesday, increasing temperatures into the upper 60s
and maybe lower 70s, most likely lower 70s for southern reaches of
our forecast area. The winds should also be lighter, as the center
of the high pressure moves over the area and the pressure gradient
slides east of the Mississippi River. The stronger meridional flow
will be confined to the Central and High Plains over the next couple
of days, therefore will not a see a great deal of moisture return as
the access to Gulf moisture will be greatly limited. For Tuesday
afternoon high temperatures, current inner-quartile spread is
between 60 and 68 degrees for most locations, and on Wednesday
between 64 and 72. Temperatures very seasonable for the start of
May. With clear skies and light winds, expecting overnight lows in
the mid to upper 30s. Current model guidance keeps frost/freeze
conditions out of the forecast area, but will need to monitor
diurnal trends closely for the middle part of this week.
Early Thursday, the closed-low over the west coast has most of its
vorticity wrapped around it and will be slow to propagate eastward.
However, there is another H5 wave in Central Canada that is
developing on the backside of the Great Lakes system that has better
flow, but because of the blocking pattern is forced southward into
the upper Midwest. This de-amplifies the H5 ridge across the Central
CONUS, and sends a weak shot of vorticity across the forecast area.
The kinematic lift with this along with the WAA allows a surface
cyclone to develop in the High Plains, and looks to back surface
winds more toward the southeast. This should provide more moisture
transport Thursday morning and into the afternoon. With the
combination of the mid-level vort max and surface response, seeing a
signal for Q-vector convergence across the forecast area that will
help lead to rain shower activity. GFS deterministic solution
depicts around 1000 J/kg CAPE developing as the H5 ridge breaks
down, which may support thunderstorm development. With the better
flow wrapped up with the two closed-low systems, the environment may
not be greatly sheared, thus limits organization potential and could
hinder severe potential. If model guidance is forcing the eastern
low eastward too quickly in this blocking pattern, there may be
slightly better shear. Once the west-coast wave comes ashore, should
be able to better refine the forecast for thunderstorm potential.
Even if instability is not fully realized, still looking at showers
across the area Thursday, with ensemble probabilities for at least
one-tenth of an inch over 90 percent along Interstate 70 and
southward, and between 50 to 60 percent elsewhere. Shower potential
continues into Friday as another vort max breaks away from the west
coast PV anomaly and creates another period of stronger convergence,
as well as return moisture flow into the region. There again is some
signal for instability to develop with stronger theta-e advection
into the region, but deep layer shear again may be displaced from
the better lift and instability. Medium to high confidence in rain
activity on Friday across the forecast area, with potential for
embedded thunderstorms. Like with Thursday, if our area is able to
tap into stronger mid to upper level flow, perhaps wind shear
becomes more prominent to support more organized activity. As for
QPF, ensembles maintain probabilities above 80 percent for at least
one-tenth of inch of QPF for our central and above 50 percent
northward. And for half an inch of QPF, looking at probabilities
above 60 percent southward and 30 percent northward.
For next weekend, lower confidence in how the large scale synoptic
pattern evolves with the break down of the blocking pattern. A ridge
likely sets up somewhere over the CONUS that could give us dry
conditions, but there also solutions that send another vort max
across the region bringing more rain shower activity. NBM guidance
has placed some low end POPs across the forecast area for next
weekend. With overall low confidence, will not make any drastic to
changes to this forecast for next weekend.
&&
.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 605 PM CDT SUN APR 30 2023
VFR conds will prevail thru the pd as sct clouds around 8kft
becomes clr skies by 02Z with just ocnl passing high clouds poss.
The main concern for aviators will be the gusty NW winds. Winds
btn 15-20kts with gusts to 30kts will diminish by 02Z to around
10kts before increasing again btn 14Z-16Z to 15-20kts with gusts
to 30kts.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Krull
Aviation...73