Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/26/20
AREA FORECAST DISCUSSION
National Weather Service Albany NY
937 PM EDT Sat Apr 25 2020
.SYNOPSIS...
High pressure will move east of New England tonight. A
complex storm system will approach from the Ohio Valley for the
second half of the weekend. Rain will overspread the region
tomorrow mixing with and even changing to snow in the higher terrain
areas for Sunday night into Monday morning, as a new low pressure
system forms near Long Island. The higher terrain will have the
better chance of accumulating snowfall, especially the southern
Greens. The coastal low pressure system will continue to bring rain
and higher terrain snow showers to start the week with cool
temperatures for late April.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 930 PM EDT, high/mid level clouds have overspread most of
the region. Temps remain mild, generally 50s to around 60
within the Hudson Valley from Albany south to Poughkeepsie, with
upper 40s to mid 50s elsewhere.
Some sprinkles were noted across portions of northern PA and the
southern/western Catskills, in association with a band of
increasing mid level frontogenesis. This band of F-gen is
expected to slowly track northward overnight and strengthen,
possibly leading to an uptick in sprinkle/light shower coverage
across portions of the eastern Catskills/Schoharie Valley
through midnight, and the western Mohawk Valley into the Lake
George/Saratoga region closer to, or just after midnight, and
SW Adirondacks well after midnight.
Otherwise, all else remains on track. Previous discussion
follows...
As of 410 PM EDT...High pressure moves east of New England and
the Gulf of Maine early this evening, as the flow flattens
briefly over the Northeast ahead of a strong mid and upper level
short-wave approaching from the OH Valley. A jet confluent
region sets up over northern NY and southeast Canada. High
pressure builds in from south of James Bay.
Clouds thicken and lower with increasing low and mid level warm
advection across the region. The low-levels of the atmosphere
remain dry, but the 3-km HRRR and NAM continue to show a lead
band of warm advection pcpn moving across the eastern
Catskills, western Mohawk Valley, the southern Adirondacks, and
the Lake Region. This pcpn is driven by the isentropic lift
should dry up east of the Hudson River Valley and produce mainly
light rain or some very light snow above 2 kft AGL over the
eastern Catskills and southern Adirondacks due to evaporative
cooling.
Lows tonight may be shortly after midnight, then slightly rise
with lows in the upper 30s to lower 40s in the valley areas, and
lower to upper 30s over the higher terrain.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
A Winter Weather Advisory has been issued from 8 pm EDT Sunday
to noon Monday for the locations at 1500 feet AGL or higher in
Bennington and western Windham Counties...
Tomorrow...The primary closed compact low moves from the Ohio
Valley to west-central PA and WV. Some short-wave energy shifts
to the Chesapeake Bay corridor with a secondary cyclone forming
in the late morning/early pm. Moisture gradually spreads
north/northeast ahead of the complex system tied to the
isentropic lift on the 290/295k surfaces. High pressure to the
north will continue to funnel some low-level dry air southward.
The column should gradually moisten with better dynamical lift
and low-level jet segment pushing northward with the warm
conveyor belt. PoPs were maintained in the likely and
categorical range in the afternoon. SPC continues to scrape the
southern most zones with General Thunder and with pockets of
elevation instability indicated by the NAM/GFS with Showalter
stability values near 0C, we will place a slight chance of
thunder near the I-84 corridor. We called it periods of rain in
the afternoon and some transition to wet snow is likely over the
southern Dacks, and the southern Greens before nightfall with a
coating to an inch or snow. Highs on Sunday will be in the
upper 40s to lower 50s in the valleys, and 40s over the higher
terrain.
Sunday night...The guidance diverges with the role of the
secondary low with the NAM keeping most of the pcpn going with
the primary low, and a dry slot trying to sneak into locations
from ALY south and east during this time frame. The GFS is
further south with the primary and its closed circulation. We
collaborated with WPC and WFO BTV and believe the 00Z and 12Z
ECMWF are most on track with the placement of this Miller Type B
system. The secondary cyclone scoots east of Long Island with a
strong east to northeast LLJ with -U wind anomalies -2 to -4
STDEVs below normal. The favorable jet dynamics and this jet
will help the pcpn to intensify in the mid to upper deformation
zone for some snowfall over the southern Greens and southern
Adirondacks. The cooling aloft with also allow for a transition
to snow over the eastern Catskills, Helderbergs, northern
Taconics and Berkshires. The dynamical and wet bulb cooling
should allow for all snow above 1500 feet and it could be
briefly an inch an hour over the southern Greens. We have total
snowfall amounts above 1500 ft at 3-6 inches. We have generally
1 to 3 inches over the southern Adirondacks and 1-4" over the
eastern and northern Catskills. 1-2" is possible over the
northern Berkshires and northern Taconics. Some wet snowflakes
are possible in the valleys with the Lake George and Glens Falls
area getting a coating to a few tenths of an inch. The diabatic
heating in the river valleys and the temps staying in the mid
and upper 30s should prevent any snow accumulation. SLR`s were
used in the 5-7:1 range over the mtns, and 3-5:1 range over
elevations below 1500 feet.
The dendritic growth zone remains high and pcpn intensity will
play a factor. Again, the southern Greens have the best shot for
the heavy pcpn. If the NAM is right on the northwest shift,
then we may have to up totals in the southern Dacks. Lows will
be in the upper 20s to mid 30s over the mountains, and
mid/upper 30s in the valleys. Some sleet could briefly mix in
over the western New England higher terrain too. The north to
northeast winds will increase to 10 to 20 mph with some gusts
around 35 mph.
Monday...The fairly weak coastal low drifts to near Cape Cod and
the broad closed H500 circulation remains over upstate NY and
New England. Occasional rain and snow showers will persist over
the forecast area due to the cyclonic vorticity advection and
steep lapse rates. The late April sun angle should disrupt the
shower activity and may it cellular with mainly rain showers in
the afternoon. We only have the advisory going to noon time.
Highs will only be in the mid 30s to around 40F over the mtns,
and mid and upper 40s in the valleys.
Monday night...The upper level low slowly shifts downstream
with the rain and snow showers diminishing. Some light snow
accums are possible over the upslope areas of the southern
Greens and western Adirondacks with a coating to an isolated
inch. Lows will fall into the upper 20s to mid 30s over the
elevated terrain and mid and upper 30s in the valley with mostly
cloudy conditions.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Departing upper level disturbance east of the region will allow for
shortwave ridging to build into the area for Tuesday. Any lingering
morning clouds or sprinkles will give way to afternoon sunshine,
with temps warming into the mid 40s to mid 50s. Continued dry and
mainly clear conditions, along with light to calm winds, will allow
for a chilly night on Tuesday night. Many spots will fall below
freezing, with just the immediate Capital Region and mid Hudson
Valley staying in the mid 30s, with upper 20s to low 30s elsewhere.
Sky cover will be quickly increasing on Wednesday as the next storm
system approaches and high pressure starts departing off to the
east. This will be yet another large closed off upper level low
approaching from the Ohio Valley. There still is some uncertainty
regarding the exact speed of this system. POPs increase to CHC by
afternoon and it may take until Wed evening or night for rain to
begin across the entire area.
With a strong southerly low-level jet ahead of the advancing storm
system, there should be a period of steady rainfall, most likely for
Wed night into Thursday. Some moderate to locally heavy rainfall
can`t be ruled out, especially across the higher elevations, where
upslope flow will enhance rainfall. With plenty of mild air, both
at the surface and aloft, p-type will be all plain rain. Daytime
temps should be in the 50s for most spots, with upper 30s to mid 40s
at night.
As the best isentropic lift shifts away, the steadiest rainfall will
end for later in the week. However, plenty of lingering clouds and
showers will continue for Thursday night through Friday, as the slow
moving upper level low passes over the region. Will keep POPs
fairly high for Thursday night into Friday with more rain showers.
Drier weather, with temps closer to normal, should arrive for
Saturday.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Low pressure developing over the Ohio Valley will track
northeast tonight into Sunday, as a secondary area of low
pressure develops near Delmarva and tracks east northeast late
Sunday and Sunday night.
Clouds will thicken tonight into early Sunday morning, but
flight categories will remain VFR. An band of sprinkles/light
rain showers may develop around KGFL overnight, but there
remains uncertainty if this precipitation will reach the ground.
Therefore, will include a VCSH at this time.
Steadier rain will then spread from south to north during the
day Sunday, reaching KPOU in the morning, KALB/KPSF mid to late
morning, and KGFL in the afternoon. At the onset of
precipitation, cigs will start in the VFR range but trend down
to MVFR for most sites (for Vsbys and Cigs). Periods of IFR
could occur by late afternoon, especially at KPSF.
Winds will become light/variable overnight, although may become
southeast to south at KALB and increase to 5-10 KT with a few
gusts up to 15-20 KT possible. On Sunday, winds will back from
the southeast into the northeast by late morning, and will
increase to 8-12 KT by afternoon, with some gusts of 15-20 KT
possible.
Outlook...
Sunday Night: High Operational Impact. Breezy. Definite RA.
Monday: High Operational Impact. Likely SHRA...RA.
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Low Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Moderate Operational Impact. Chance of SHRA.
Wednesday Night: High Operational Impact. Likely RA.
Thursday: High Operational Impact. Breezy. Definite RA.
&&
.FIRE WEATHER...
High pressure will move east of New England tonight. A
complex storm system will approach from the Ohio Valley for the
second half of the weekend. Rain will overspread the region
tomorrow mixing with and even changing to snow in the higher terrain
areas for Sunday night into Monday morning, as a new low pressure
system forms near Long Island. Cool and unsettled conditions
continue for Monday.
The RH values will increase to 70 to 90 percent Sunday morning,
and then lower to 55 to 70 percent only Sunday afternoon with
rain overspreading the region. The RH values will remain
elevated at 90 to 100 percent Monday morning with rain and
elevation snow persisting.
The winds will light from the east to southeast at less than 10
mph tonight. They will increase from the east to northeast at 5
to 15 mph on Sunday. As the secondary low forms near Long
Island, expect the winds to increase from the north to
northeast at 10 to 20 mph with some gusts in the 25 to 35 mph
range Sunday night into Monday.
&&
.HYDROLOGY...
Widespread hydrological problems are not expected prior to the
middle of next week.
There are two main storm systems that look to bring widespread
precipitation to eastern NY and western New England over the next 7
days. The first will be a long duration event occurring late
tonight into Monday with mainly rain for valley areas and rain
transitioning to accumulating snow for elevations above 1500ft
before turning back to rain or rain/snow mix. Total QPF or
liquid equivalent for this event ranges between 0.75 and 1.25
inches. Some elevated river flows are possible, but no flooding
is expected at this time.
The second system may bring another long duration pcpn event
that looks to arrive Wednesday night into Thursday. Guidance
shows a plume of moisture rich air feeding into the Northeast
allowing the steadiest precipitation to occur through Thursday
with lingering wrap around showers possible into Friday. Since
there are strong moisture connections out of the Gulf of Mexico
and Atlantic, widespread amounts of 1 to 2 inches are possible
with this second event and given that soils will likely still be
saturated from the Sunday/Monday event, elevated river rises
are expected and if terrain effects lead to locally higher
amounts, then river responses will need to closely monitored.
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...None.
MA...None.
VT...Winter Weather Advisory from 8 PM Sunday to noon EDT Monday
for VTZ013-014.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...KL/Wasula
SHORT TERM...Wasula
LONG TERM...Frugis
AVIATION...KL/Rathbun
FIRE WEATHER...Wasula
HYDROLOGY...Speciale/Wasula
Area Forecast Discussion
National Weather Service Bismarck ND
947 PM CDT Sat Apr 25 2020
.UPDATE...
Issued at 947 PM CDT Sat Apr 25 2020
Model guidance is in pretty good agreement of fog developing in
the James River Valley overnight due to the weak high pressure
currently over central North Dakota, so added in patchy fog with
this update. There is some indication that fog might expand
further north to the Turtle Mountains. Only other change with this
update was to increase cloud cover, as high clouds have begun
streaming in across the west.
UPDATE Issued at 643 PM CDT Sat Apr 25 2020
A few scattered rain showers continue to linger in the James River
Valley area, but precipitation chances are quickly declining. We
have yet to see any lightning with any showers in the forecast
area, so went ahead and removed the chance for thunderstorms for
this evening. No major changes to the forecast with this update,
just blended in the latest observations.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 212 PM CDT Sat Apr 25 2020
Critical fire weather conditions are possible in northwest North
Dakota Sunday. This is where the greater potential for the lowest
RH and stronger winds to overlap and a Fire Weather Watch has
been issued.
This afternoon, the synoptic pattern was characterized by a broad
trough over the eastern CONUS, a ridge building over the Rockies,
and a trough developing over the Pacific Northwest coast.
Northwest flow was over the Northern Plains with an embedded
shortwave trough placed over the eastern Dakotas. Scattered
showers and possibly a few thunderstorms are expected to persist
in the James River Valley counties into this evening before loss
of heating and a weak surface high cuts off precipitation.
Southerly flow develops overnight in our west as the
aforementioned upstream and attendant surface low develop over
southwest to south-central Canada.
By Sunday morning, the frontal trough is expected to reach the
Montana/North Dakota border with south/southwesterly winds in the
prefrontal region to the east. As the surface low moves eastward
through the day, dry westerly surface flow will fill in behind
with sustained surface winds of 15 to 25 mph expected and clearing
skies. As usual, the RAP continues to be the low- end of guidance
for surface dew points...which has performed generally well in
these dry post- frontal events. Blending the RAP with the NBM to
create the relative humidity forecast, minimum RH values dipping
into the teens in northwest North Dakota are expected. This,
combined with the winds, puts conditions at near critical for fire
weather Sunday afternoon and evening. The wiggle room in the
forecast will be the relative humidities, with these events known
to produce even lower RH values than forecast. Thus the Fire
Weather Watch was issued with future shifts able to judge if an
upgrade is necessary.
In other weather potential, there will be a chance of showers
along the surface trough, favoring the northern and central to
eastern portions of the state where mid-level height falls to the
north overlap with diurnal heating timing. Mid-level lapse rates
look fairly meager so thunder was left out of the forecast for
now.
.LONG TERM...(Sunday night through Saturday)
Issued at 212 PM CDT Sat Apr 25 2020
A chance of showers and thunderstorms is expected Monday evening
with breezy northwest winds on Tuesday. Warming temperatures are
then expected through the middle of the week.
High pressure develops behind the frontal passage Sunday night and
into Monday as mid-level heights build ahead of the next oncoming
shortwave.
Monday evening, a shortwave and surface trough are expected to
move out of the northern Rockies and dive southeast through the
Northern Plains through Tuesday. Showers and thunderstorms should
accompany the frontal passage Monday evening beginning in the west
and moving eastward overnight. Behind the front, winds will
increase on Tuesday as northwest flow and modest pressure rises
overlap in west/central North Dakota. Winds are currently sub-
advisory criteria in the forecast, but will continue to highlight
in the HWO as they`re still near criteria.
The following several days are kept dry in the forecast as
guidance is consistent in developing an upper level ridge over the
Rockies and transitioning it eastward over the Northern Plains by
Thursday evening. Ensembles have enough signal for a ridge
breakdown and shortwave arrival Thursday evening to have chance
PoPs. Otherwise, the pattern brings warmer temperatures with the
NBM bringing highs in the upper 70s in the southwest on Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 643 PM CDT Sat Apr 25 2020
VFR conditions expected at all terminals through the 00Z TAF
cycle. Scattered showers in the James River Valley are expected to
end by 03Z. Cold front will move through the forecast area
tomorrow, with winds transitioning from southerly to westerly at
15 knots, gusting to 25 knots. Some rain showers are possible in
portions of northwest and central North Dakota, but only included
at KMOT at this time, and even that is only marginal confidence.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Sunday afternoon through Sunday evening
for NDZ001-002-009-010-017.
&&
$$
UPDATE...MJ
SHORT TERM...AE
LONG TERM...AE
AVIATION...MJ
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
626 PM CDT Sat Apr 25 2020
.DISCUSSION...Updated for latest aviation discussion below.
&&
.AVIATION...VFR to MVFR conditions are expected through this
evening, before generally VFR conditions return and persist
through the remainder of the TAF period. There have been numerous
storms southwest of the RGV in Mexico and there is a chance a few
of these could make a run for the border late this evening through
tonight. At this time, confidence is lower that any convection
would make it to MFE, and even lower for any storms near HRL and
BRO. Any tall CB across the west should be avoided as they may
contain hail.
&&
.PREV DISCUSSION... /issued 236 PM CDT Sat Apr 25 2020/
SHORT TERM (Tonight through Sunday Night): The weak cold front
has started pushing into the northern Ranchlands this afternoon
with a light to moderate easterly low level flow prevailing over
the RGV. (Dewpoints north of a Baffin Bay to LRD line is in the
50s while south of this line dewpoints still remain in the upper
60s to lower 70s) This cold front is expected to edge through the
rest of Deep South TX and the RGV later this afternoon and evening
allowing for some generally drier air to finally filter into the
region later tonight into Sun. The GFS is the coolest of the
NAM/GFS/ECMWF trio with both the NAM and ECMWF temps coming in on
the warmer side. Will lean closer to the NAM/ECMWF solution since
the GFS is the current outlier.
Pops are a bit tricky in the immediate near term forecast. The
latest observed LAPS CAPE values show some pretty unstable CAPE
(3000-4000 J/KG) pooling along the Rio Grande and just south of the
river near and ahead of the approaching cold front. LAPS also
currently shows pretty decent CIN values (100-200 J/KG) in place
over Deep South TX and NE Mex limiting conv development.
Accordingly, the immediate KBRO radar imagery shows no echoes
threatening the RGV and Deep South TX. However, the latest HRRR and
RAP model runs are persistent in developing conv over NE Mex as the
cold front pushes up against the higher terrain there. Tha RAP
guidance keeps most of the conv confined south of the Rio Grande
while the HRRR tries to push some sct conv northwards across the
western portions of the region. The short term NAM and ECMWF also is
hinting at some isold/sct conv out west overnight into early Sun
morning. So will maintain a mention of this mainly during the
overnight hours. Since this appears to be firing after max heating
and in the lower CAPE values north of the cold front, will not
mention any potential for svr conv. However, an isold strong
thunderstorm cannot be ruled out.
The air quality may temporarily improve a little bit as the bulk of
the particulate matter from the agricultural burning in Mexico will
likely be shifted a little more to the S and SW out of the RGV.
However, as the SE surface winds return Sun Night, expect the
hazy/smoky conditions to return once again after this weekend.
LONG TERM (Monday through Saturday): Fairly benign pattern to
begin the long term period with generally zonal flow in place
aloft and surface high pressure to the east across the eastern
Gulf of Mexico and into the western Atlantic. Within the flow
aloft, a couple of very weak perturbations move across Mexico
into Texas but these should not affect the weather besides
generating convection over the higher terrain of Mexico. Do
expect for temperatures to run above average into midweek,
especially on Tuesday and Wednesday.
A developing storm system across the upper Midwest will likely
result in breezier conditions on Tuesday. Winds then subside on
Wednesday as a weak front advances across the region late in the
day. This frontal boundary should provide a slight chance for rain
and thunderstorms across Deep South Texas. This front could bump
the temperatures down a couple of degrees for Wednesday night and
Thursday. Otherwise, the temperatures will then rebound back to
well above average levels with little rainfall as surface high
pressure moves atop the region and a strong mid-level ridge
develops across the Desert Southwest.
MARINE (Now through Sunday Night): The low level surface flow
across the lower TX Bay and Gulf waters will shift around from the
E to the NE later this afternoon as the weak cold front moves
steadily southwards. The PGF is not expected to increase
significantly after the fropa, so do not anticipate drastic
increases to the wind and swell activity through Sun Night. The
marine conditions may briefly reach SCEC criteria later tonight
into early Sun Morning mainly for the far offshore waters. The SE
surface flow will then return pretty quickly later Sun into Sun
Night. No SCA conditions expected through Sun Night for either the
lower TX Bay and Gulf waters.
Monday through Thursday night: Moderate to breezy southeasterly
winds are expected early next week as the pressure gradient is
expected to strengthen in response to a storm system across the
upper midwest. Exercise caution to small craft advisory levels
may be possible. Winds subside Wednesday into Wednesday night
as a weak cold front advances into the region. This will shift
winds out of the east-northeast. Winds return to out of the
southeast into Thursday night. Seas improve but remain of
moderate levels from Wednesday through Thursday night.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
56-Hallman...Aviation
Area Forecast Discussion
National Weather Service Quad Cities IA IL
802 PM CDT Sat Apr 25 2020
.UPDATE...
Issued at 802 PM CDT Sat Apr 25 2020
The deformation axis of rain over north central Illinois
continues to weaken and drift slowly eastward this evening. KDVN
dual pol radar and MRMS are showing rainfall rates of less than a
few hundredths of an inch per hour over southeast Bureau and
Putnam counties over the past couple hours. At the current rate,
the light rain or sprinkles should end over this area between 9
pm and 10 pm.
With the threat of heavy rainfall over, the flood watch has been
cancelled.
&&
.SYNOPSIS...
Issued at 254 PM CDT Sat Apr 25 2020
A rather pleasant or not so pleasant Spring day was seen today
depending on where you were located. Clouds and rain kept points
along and east of the Mississippi in the 40s, whereas some filtered
sunshine and dry conditions were seen in the northwest sections of
the CWA, with afternoon temps in the upper 50s and even low 60s.
Breezy northeast winds were also seen.
SPC mesoanalysis page and the 16z RAP model run showed the
heavier fgen band nicely this morning in the 850-700 mb layer,
which stayed mostly to the east of the CWA for much of the day.
Estimated rainfall rates between 0.1" and 0.25"/hr fell for
several hours with the highest 6-hr rain amounts per MRMS highest
in Bureau and Putnam counties in IL, where three quarters to 1.50"
fell. Fortunately, this was in a different location than the rain
that fell prior to 8am this morning.
&&
.SHORT TERM...(This Evening through Sunday)
ISSUED AT 254 PM CDT Sat Apr 25 2020
Forecast focus in the near term is on precipitation exiting the area
and cloud/temperature trends overnight.
Tonight...Upper low will continue to push east into the Ohio river
valley this evening and overnight, with associated def zone also
moving east out of the area. Heavy precipitation has shifted east
out of the initial flood watch area and thus have cancelled early
for McDonough and Warren counties. An additional quarter to three
quarters of an inch will be possible this evening in our far eastern
counties and this may cause some ponding of water in fields in areas
that already received over 1" of rain from this morning. After
collaborating with neighboring offices, have issued an areal flood
watch for Bureau and Putnam counties until 06z tonight to account
for the additional rain. All precipitation should exit the area
early Sunday morning with clearing skies. Sunday lows will drop into
the upper 30s and lower 40s. With north winds remaining above 5 mph
overnight and recent rainfall do not anticipate temperatures from
dropping lower than forecast at this time.
Sunday...warmer and dry conditions will be found, as a surface ridge
moves overhead with plentiful late April sunshine. Forecast
soundings show mixing up to at least 850 mb during the day, which
will boost temperatures into the lower to middle 60s. This is closer
to normal for this time of year.
.LONG TERM...(Sunday Night through Saturday)
ISSUED AT 254 PM CDT Sat Apr 25 2020
Monday and Tuesday
Southerly flow ahead of two separate waves of low pressure will push
warmer air into the region with highs in the 60s on Monday and mid
60s to low 70s (south) on Tuesday. Scattered light showers are
possible Monday as elevated WAA/isentropic lift translates through
eastern Iowa and northwest Illinois. Have rain chances between 20-
40%, and expect most areas to receive less than a tenth.
On Tuesday, a much stronger mid-level wave is forecast to drop
southeastward out of the Northern Plains and continue to dig into
the Upper to Mid Mississippi Valley. A period of showers and
thunderstorms is likely with this system with the best chances from
late Tuesday morning into Tuesday night. It is too early to assess
the risk for severe weather but it`s something to monitor.
Some of the rainfall could be heavy as PWATs peak near 1.25 inches.
Model consensus favors the eastern CWA with the heaviest rain,
possibly 0.50-1.00"+. The track of the upper low will influence how
far north a dry slot reaches later Tuesday night. The ECMWF is most
aggressive on pushing it through our entire CWA.
Wednesday
Wrap around deformation rain is possible on Wednesday in a cold air
advection regime, which could make for a raw day if the ECMWF
verifies. Model blend temps are in the upper 50s to mid 60s and may
need to be lowered in later updates.
Thursday On
Models in good agreement on a building upper ridge late in the week
and drier looking pattern. Model blend highs are in the 60s for
Thursday and 70s Friday. Uttech
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
ISSUED AT 608 PM CDT Sat Apr 25 2020
VFR conditions will prevail overnight into Sunday as weak high
builds into the area behind the storm system moving through the
Ohio River Valley. Initial gusty northeast winds early this
evening will become light and variable overnight into Sunday.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...Sheets
SYNOPSIS...Gross
SHORT TERM...Gross
LONG TERM...Uttech
AVIATION...Sheets
Area Forecast Discussion
National Weather Service Peachtree City GA
1055 PM EDT Sat Apr 25 2020
.UPDATE...
Convection has moved out of the area with just high clouds
streaming across. have made adjustments to hourly temperatures and
dewpoints and dropped POPs through the overnight hours. Updated
forecasts will be issued shortly.
&&
.PREV DISCUSSION... /Issued 314 PM EDT Sat Apr 25 2020/
SHORT TERM /Tonight through Sunday Night/...
Closed upper low continues to push through the Missouri Valley and
into the Tennessee Valley at this hour. Although diffluence ahead
of this system has created the lift for some light shower,
instability has been the limiting factor thus far for more robust
activity. CAPE has been largely on the order of 500 J/KG to 1000
J/KG thus far but RAP indicates within the next 6 hours a marked
increase with in excess of 2000 J/KG by late this afternoon into
the evening hours for far North GA. Will therefore not jump on any
big changes to the forecast as activity should fill in nicely for
aforementioned areas along with the threat for severe storms.
Hail still the primary threat given cold mid levels but
microbursts and to a lesser extent, tornadoes remain a
possibility with this activity through this evening.
Upper low to actually move north of the area tonight but appendage
of vort max will bring additional lift to far north GA. Although
instability will have subsided by then, still enough moisture and
lift to warrant isolated to low end chance shower chances. Cooler
behind this system and despite the cloud cover, still some lower
to mid 40s expected for far NW GA.
Clearing conditions for Sunday bu the drier and much windier
conditions will pose their own issues. Likely that we will need a
wind advisory and a Fire Danger Statement for conditions that
develop by tomorrow afternoon. Will allow mid shift to refine and
issue both of these.
Deese
LONG TERM /Monday through Saturday/...
The long term period picks up on Monday morning with surface high
pressure building across the local forecast area. With high pressure
in place, expecting to have calm and dry weather on Monday with an
increase in cloud cover for Tuesday ahead of the next low pressure
system.
By early Wednesday a mid-level trough is forecast to move into the
area bringing southwesterly flow aloft and moisture to the area. The
associated surface low is expected to be centered north of Georgia
near the lower Great Lakes region on Wednesday before the low lifts
to the northeast. Models have come into better agreement with this
system although there are still some small discrepancies in low
placement and strength. Regardless, a front is expected to move
through the area on Wednesday with showers and thunderstorms
possible.
Rainfall totals for this system around around a quarter inch to an
inch with the highest totals across northern Georgia and the higher
elevations in the northeast. By late Wednesday, the GFS is showing
the front clearing the area in the evening bringing some wrap around
precipitation to far north Georgia. On the other hand, the ECMWF
progresses more slowly, clearing the front on Thursday afternoon
with wrap around precip across far north Georgia late Thursday into
early Friday. Decided to go with a blend for pops in this period
clearing the precipitation by Thursday afternoon. After this system
passes, upper level and surface level ridge is expected to build
into the area, keeping forecast relatively quiet through the end of
the long term.
Temperatures through the extended will generally be around average
with highs generally in the 60s and 70s to lower 80s across the
area, with low temps in the 40s and 50s.
Reaves
AVIATION.../Issued 729 PM EDT Sat Apr 25 2020/
00Z Update...
VFR conditions will persist through the TAF period. Winds will be
southwest to west at 10-15kts with gusts 20 to 28kts throughout
the entire period.
//ATL Confidence...00Z Update...
Medium to high all elements.
Atwell
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 53 67 44 74 / 20 5 5 5
Atlanta 53 66 46 71 / 20 10 10 5
Blairsville 47 55 39 66 / 50 40 40 5
Cartersville 50 62 41 71 / 30 20 10 5
Columbus 54 74 48 76 / 5 0 5 5
Gainesville 53 61 45 71 / 40 10 10 5
Macon 54 74 46 76 / 5 0 5 5
Rome 50 62 42 71 / 30 20 10 5
Peachtree City 51 68 43 73 / 10 5 5 5
Vidalia 58 77 51 76 / 10 5 5 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Atwell
LONG TERM....Reaves
AVIATION...Atwell
Area Forecast Discussion
National Weather Service Grand Forks ND
937 PM CDT Sat Apr 25 2020
.UPDATE...
Issued at 936 PM CDT Sat Apr 25 2020
Any lingering thunderstorms have weakened over our area, but
light showers are still lingering over eastern ND and northwest
MN. This activity is still expected to slowly spread east and then
fall apart with main trough axis shifting east of our CWA. Mid
level stratus is lingering though and if this doesn`t clear by
morning could hold our overnight lows (especially in our east).
Adjustments during this update focused on timing/coverage of
lingering light showers, and held off on temps (clearing could
still spread east by daybreak).
UPDATE Issued at 659 PM CDT Sat Apr 25 2020
Mid level trough axis is still centered near our CWA, with the
surface trough roughly along the REd River Valley. Where there is
clearing there has been enough instability to still support a few
weak thunderstorms, however overall trend has been weakening.
Lighter showers may lingering later tonight in our east, but most
locations should see a drying trends ahead of the next mid level
shortwave/front Sunday afternoon. Adjustment made to reflect
coverage/trends. Due to limited (and quickly decreasing)
instability, isolated lighting and light rain will be only impacts
this evening.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 335 PM CDT Sat Apr 25 2020
Main surface trof axis, now along a Lidgerwood to Finley to
Niagaraline, will continue a slow eastward shift through the
late afternoon and evening period... crossing the RRV corridor
through the dinner hour and much of northwest Minnesota throughout
the evening.
Convection along and ahead of trof axis in southeast ND and
adjacent portions of northwest through west-central MN continues
to become more diffuse as the focus for mid level energy and
surface heating have both shifted well south into eastern Sd and
southwestern MN. However isolated thunderstorms are still possible,
espousal in the southern RRV where early afternoon sunshine and
surface heating was prevalent. The 19z RAP guidance maintains a
fairly broad area of some 200-300 J/KG of 0-2 km CAPE alg and
south of the Hwy 2 corridor through 02z, so convective elements in
the overall pattern are likely to persist well into the evening.
The 12z and 18z NAM runs have been overly wet and quite bullish,
keeping a fair amount of precipitation across northwest MN during
the overnight. However CAMs have steadily shown that convection
should weaken considerably through early evening and essentially
shutdown with nightfall, so have favored this drier soln.
Sunday will see a second weak shortwave move into and across the
area with scattered showers and isolated thunderstorms again
possible through the afternoon and evening hours...though areas
north of the I-94 corridor seem most probable at this point.
Seasonably mild temperatures continue through Sunday into Monday
morning... with highs from the upper 50s to the mid 60s, and lows
in the 40s.
.LONG TERM...(Monday through Saturday)
Issued at 335 PM CDT Sat Apr 25 2020
Active weather coming up for the beginning of the extended period,
with chances for showers and thunderstorms early Mon, and on Tue. A
lull in the action should follow for mid week. Best chances
for more impactful activity would appear to be on Tue.
NW flow regime will see a shortwave moving through Sun night into
Mon. On Tue a more substantial wave and area of sfc low pressure
will be in play, along with more of a moisture feed. So with a
decent boundary approaching and maybe 500 J/kg of CAPE available
would expect a better chance for more sustained tstm activity during
the day on Tue and maybe into the evening. marginally cooler temps
will roll in behind the system Tue night into Wed.
There are good indications that a decent ridge will start to build
over the region for Thu and Fri moving temps trough the 60s and
toward that 70 degree mark. Overnight lows mostly in the 40s, with
30s Tue and Wed night. Another chance for showers could come Fri,
but plenty of variability exists this far out.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 659 PM CDT Sat Apr 25 2020
Besides lingering scattered showers minimal impacts to aviation
during the evening period, with prevailing VFR conditions. There
have been some easterly winds 10-15kt, but these should diminish
and become light/variable tonight. Models show a period of stratus
possibly reduce ceilings over northeast ND to MVFR (maybe even
IFR) late tonight after 10Z which could impact KDVL or even as far
east as KGFK. There should be drier air moving in, so I`m not
confident in how low or widespread this would be. I induced
mention at KDVL where there is more certainty, but held off of
KGFK. This should lift 14-15Z if it occurs. Showers and isolated
thunderstorms should develop into northeast ND as a front
approaches late Sunday afternoon, with the best chances Sunday
evening/Sunday night along/north of Highway 2.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
River point flood warnings continue across portions of
the region. Refer to the latest flood warnings and statements for
detailed information on specific locations.
&&
$$
UPDATE...DJR
SHORT TERM...Gust
LONG TERM...WJB
AVIATION...DJR
Area Forecast Discussion
National Weather Service Louisville KY
747 PM EDT Sat Apr 25 2020
...Updated Aviation Discussion...
.Forecast Update...
Issued at 600 PM EDT Sat Apr 25 2020
Sfc low is just south of Evansville, with an occluding front arcing
east and then SE, just west of Bowling Green but just north and east
of Nashville. A fairly solid rain shield covers southern Indiana and
much of central Kentucky, keeping a lid on SVR potential. There is a
small dry slot near Lake Cumberland, and it will have a very limited
opportunity to destabilize ahead of any convection along the
occluded front. So we can`t rule out a strong storm or two down that
way, but that window is closing and the more favorable environment
for storms to rotate is solidly in TN per latest SPC mesoanalysis.
Expect an update shortly to better convey the precip trends, which
may involve carrying the categorical POP into the evening for more
of the area. Over the next hour or so we expect to tone down our
messaging as the severe threat diminishes.
&&
.Short Term...(This evening through Sunday)
Issued at 315 PM EDT Sat Apr 25 2020
18Z surface analysis reveals an area of low pressure near Mt. Vernon
IL with a warm front extending southeastward through parts of
western Kentucky. Just ahead of this low pressure system,
convection has fired across west-central KY in the Pennyrile region.
This area saw a bit of clearing and insolation earlier this
afternoon which allowed temps to surge well into the upper 60s.
Current mesoanalysis showed a bubble of instability from Hopkinsville
northward to Owensboro where 750-900 J/Kg of CAPE was available and
this area was coincident with moderately steep lapse rates of
around 7-7.4 C/KM. The storms have been pulsing up and down
producing up to 1 inch hail. Latest high resolution guidance
suggests that this convection may organize into a short segment line
and lift northeast, posing a threat of near severe hail, heavy
rainfall, lightning, and gusty winds across Hancock, western
Breckinridge, and Perry county IN over the next hour or so.
Instability does wane a bit to the north and east of the current
convection where earlier cloud cover has limited heating and near
surface instability.
Further south and east, mainly across the karst region, ongoing
cloud cover and convective debris has thus far limited instability
across the region. Convection has developed across west-central TN
as expected and should continue to move northeastward this
afternoon. While shear profiles remain favorable for severe
convection, aforementioned concerns about instability results in
lower certainty to severe potential. Latest HRRR guidance continues
to show the potential for stronger storm development across southern
KY this afternoon. Overall, thinking is that we`ll see widespread
rain showers, with isolated to scattered stronger storms developing.
Highest threat of severe weather still looks to remain south of a
line from roughly Bowling Green over to Jackson and points south.
Strongest storms would be capable of hail and damaging winds.
However, shear profiles are strong enough that an isolated tornado
can`t be ruled out.
Convection should continue to move eastward and diminish in
intensity this evening as the surface low moves through central
Kentucky. Widespread rain showers will continue on the backside of
the system this evening and will persist into the overnight hours.
Lows tonight look to drop into the upper 40s.
For Sunday, widespread cloudiness will continue with scattered to
numerous rain showers continuing across the region. The shower
activity looks to diminish in coverage by late afternoon, perhaps
lingering into the evening in the east. Highs on the day will
likely range from the lower 50s over across the Bluegrass region and
the I-75 corridor, with middle middle 50s across the I-65 corridor.
Some partial clearing could take place across the far west by
afternoon which may allow temps to warm into the upper 50s.
.Long Term...(Sunday night through Saturday)
Issued at 245 PM EDT Sat Apr 25 2020
By Sunday evening the upper level trough axis will lie over the
spine of the Appalachians with the surface low out east over the
Garden State. Any remaining light rain should shut off around
midnight in our eastern counties as wrap around moisture exits in
the area. Low amplitude ridging aloft and associated surface high
pressure will usher in drier air presenting the OH Valley with a
pleasant Monday with morning temps in the high 30s. Could see a
patchy fog scenario in the AM hours if clouds roll out early enough
during the night to allow for sufficient radiational cooling.
Otherwise, mostly sunny skies and light winds will see max temps
rise into the mid 60s.
By Tuesday a shortwave ejecting SE out of Canada will undergo lee-
side cyclogenesis forming a closed low aloft and bringing showers
and thunderstorms back to southern Indiana and central Kentucky from
Tuesday through Thursday. Warm sector air ahead of the cold front
and a modest LLJ will allow for a chance of showers through the day
on Tuesday. Showers become more widespread Tuesday night and
throughout the day Wednesday as the cold front sweeps through the
region. Best chance of storms will likely be Wednesday afternoon
into early evening with the aid of actual frontal lifting. The low
center is progged to track across the Lower Great Lakes, which could
place our area in a more favorable environment for potential severe
weather, though dew points at this time are only expected to reach
into the mid 50s with highs in the upper 60s. Will keep an eye on
this system as newer data becomes available.
By Wednesday evening, the vertically stacked low will begin moving
east with wrap around moisture prolonging cloud cover and light rain
chances through Thursday morning. Removed any mention of
thunderstorms on Thursday as model soundings show a strong
subsidence inversion at around 850mb capping any deep convective
potential. Therefore, expect to see dry conditions for the latter
half of Thursday with the exception of any pop up diurnal showers.
Friday also looks to be dry as high pressure returns to the region.
NW flow aloft will allow for subtle impulses to ride along the
northern stream that could bring rain shower chances back to the
area on Saturday.
&&
.Aviation...(00Z TAF Issuance)
Issued at 745 PM EDT Sat Apr 25 2020
Rain is currently being seen across much of the area and is expected
to continue into Sunday as a surface low moves northeast along
the Ohio River, with some breaks in the rain possible overnight.
Ceilings are currently MVFR to VFR and look to lower into IFR
range over the next few hours. IFR ceilings will then persist into
tomorrow morning, eventually lifting from west to east during the
day on Sunday as the rain pushes off to the east.
Winds will start off out of the southeast and then shift to the
west/northwest tonight as the low slides off to the east, with
sustained wind speeds increasing to 10-15 kts. Wind gusts of 20-30
kts will be possible tonight and into tomorrow, eventually
decreasing by Sunday evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...RAS
Short Term...MJ
Long Term....CG
Aviation...JML
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1052 PM EDT Sat Apr 25 2020
.SYNOPSIS...
A warm front will push north through the region this evening.
Another low pressure system will pass to the north late tonight
pushing a weak cold front through tomorrow. A stronger cold
front will cross the area Monday morning with high pressure
building in behind it. A strong cold front will impact the
region mid to late next week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 1000 PM Sat...Impressive shortwave trough continues to pivot into
the TN/OH valleys this evening. The associated warm front is
pushing northward slowly, currently settled around Cape Fear and
spread NEwrd nearly paralleling our southern coast up to Cape
Hatteras. This boundary is expected to push N over our CWA and
priming the atmosphere for decent instability overnight.
A dry line (well defined by Td gradient) will be approaching
from the west but the best upper level support and omega will be
displaced north and west towards the Triad. However, an upper
level dry slot will be nosing into the region overnight
depriving the region of deep moisture, though forecast soundings
are beginning to show a weaker dry slot overnight and PWAT
values over 1 inch, but uncertainty still remains regarding how
much impact this will have on convective development.
Latest 00Z hi res CAM runs hold onto a line of convection firing
overnight, beginning shortly after 06Z. MLCAPE values across a
variety of hi res models maintain a range of 1500-2500 J/kg with
ample with mid- level lapse rates up to 7 C/km. With low LCL
heights, up to 40 kt of 0-1km shear, 60+ kt of 0-6 km shear, and
consistently curved hodographs, tornadoes continue to be a
concern overnight. The 00Z HRRR shows SC values above 10 and STP
values nearing 5 for much of the southern CWA. It is notable
the 00Z HRRR also showed a decent line of discrete cells
covering our southern coast and infiltrating as far inland as
the coastal plains, essentially covering the entire CWA. While
the greatest severe potential remains along the southern coast,
it is worth emphasizing the entire CWA has a conditionally
sufficient atmosphere conducive for severe weather.
To reemphasize, this threat is highly conditional on a
sufficient lifting mechanism being present and drier air aloft
not depriving the environment of necessary moisture. If storms
do fire, the highest threat window is between 06-12z overnight.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
As of 1000 PM Sat...No changes to prev disc.
Prev disc...The boundary/front will sweep offshore pushing any
potential convection well off the coast with dew points falling
quickly during the day and skies clearing. Despite increasing
CAA late as the upper low lifts north, low- level thicknesses
remain high at around 1385-1390 m along with gusty southwesterly
flow. Thus it should be another warm day with highs climbing
into the upper 70s to potentially a few 80s closer to the coast.
The atmosphere will be well mixed up to 850 mb with winds there
of 30-40 kt, so some gusts to 20-25 kt are likely especially
across the coastal plain.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
As of 315 AM Sat...Mainly dry conditions early next week before
the next frontal system impacts the area Wednesday night
through Thursday.
Sunday night and Monday...The low will move off the Northeast
coast Monday morning, bringing a stronger cold front Monday
morning. While there is some modest pre- frontal moisture
convergence, persistent dry air aloft is expected to win-out,
making precip unlikely. Increased cloud cover associated with
the frontal passage and better CAA behind this front will limit
highs Monday to the mid- 60s to near 70.
Tuesday through Wednesday...Ridging aloft builds overhead
Tuesday and Tuesday night, keep a dry forecast in place. Surface
high pressure passes south of the area during this time,
settling offshore Wednesday as moisture advection begins to
increase. Tuesday will be seasonable, with Wednesday a few
degrees warmer.
Wednesday Night through Friday...The next cold front, associated
with stacked low pressure that will lift from the Midwest across the
Northeast through the second half of the week, will impact the area
Wednesday night and Thursday. Showers and thunderstorms are expected
with this system, with strong low level wind shear thanks to a pre-
frontal LLJ bringing the potential for organized convection. The
severe weather threat will be refined in subsequent forecast
updates.
The cold front is expected to cross the area sometime Thursday into
Thursday night, with high pressure builds back in Friday, bringing a
return to settled weather.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Short Term /through 00z Sunday/...
As of 730 PM Sat...Stratus begins to break for the southern TAF
sites as seen on satellite. Expect pred VFR conditions tonight
for southern sites, but MVFR conditions for northern sites as
lower decks look to linger through the overnight as a warm front
moves north. Possible LLWS is suggested by models as the
boundary moves north over the TAF sites after midnight, veering
vertical wind profiles and forming a strong LLJ. Hi res models
show a broken line of showers and tstms forming after 06z and
pushing west to east over the TAF sites. Best storm coverage
will likely be over the southern half of the region where the
best instability is forecasted to develop. Cigs look to remain
at MVFR for a few hours once the storms move through. VFR
conditions will return after daybreak Sunday with gusty SW winds
up to 20-25 kt.
Long Term /Sunday night through Wednesday/...
As of 320 AM Sat...VFR conditions prevail Sunday night. A cold
front crossing the area Monday morning could bring some low
cloud, but the potential for flight restrictions is uncertain.
VFR returns later Monday and prevail through midweek.
&&
.MARINE...
Short Term /Tonight and Sunday/...
As of 350 PM Sat...Latest local obs and buoys show seas have
finally dropped to around 4-5 feet across the waters today in
northeast to easterly flow of 10-15 kt. Winds will veer
southerly overnight becoming southwesterly by daybreak Sunday as
a warm front advances north across the waters. Winds increase
back to 20-25 kt with gusts up to 30 kt, and seas respond in
turn reaching a peak of 7-9 feet by late Sunday. New SCAs have
been issued starting overnight and extending well into Monday as
seas slowly subside.
Long Term /Sunday night through Wednesday/...
As of 330 AM Sat...Low pressure crossing the Mid-Atlantic will
keep breezy southwesterly winds in place Sunday night. Elevated
seas of 5-8+ ft in mainly southerly windswell will occur during
this times, and SCAs will be need for most of the marine area.
A cold front will cross the waters Monday, with a brief
northwesterly surge behind it. Light winds then prevail Tuesday
as high pressure passes south of the area, allowing seas to
gradually subside, and bringing the best period for marine
weather through the long term period. Southwesterly flow and
windswell increases again Wednesday ahead of the next cold
front.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement through Sunday evening for NCZ195-196-
199-204-205.
MARINE...Small Craft Advisory from 11 AM Sunday to 4 AM EDT Monday for
AMZ135.
Small Craft Advisory from 2 AM Sunday to 8 PM EDT Monday for
AMZ152-154.
Small Craft Advisory from 2 AM Sunday to 2 PM EDT Monday for
AMZ156-158.
Small Craft Advisory from 11 AM Sunday to 2 PM EDT Monday for
AMZ150.
&&
$$
SYNOPSIS...MHX
NEAR TERM...ML
SHORT TERM...ML
LONG TERM...RF/CB
AVIATION...CB/ML
MARINE...CB/MS