Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/23/17
Area Forecast Discussion
National Weather Service Albany NY
1043 PM EDT Thu Jun 22 2017
.SYNOPSIS...
A more humid air mass will return tonight into Friday
as a warm front moves through the region, along with increasing
chances for showers and thunderstorms, some of which may produce
locally heavy rainfall. The showers and thunderstorms should
continue Friday night, before gradually tapering off Saturday as a
cold front moves through and south of the region. Another upper
level disturbance could trigger a passing shower or thunderstorm
Sunday.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1043 PM EDT...A few light rain showers associated with
the warm advection/isentropic lift ahead of a warm front over
west- central NY extending southeast over the lower Hudson
Valley and Long Island continues to lift slowly north/northeast
tonight. The 00Z KALY sounding continues to be dry in the low-
levels with mid-level moisture between 7-12 kft AGL. The PWAT
has increased from 0.70" at 12Z to 1.32". We slowed down the
trend for more widespread showers and sct thunderstorms into
locations west/northwest of the Hudson River Valley until around
midnight or shortly thereafter. The latest NAM12 and the 3-km
NAM and HRRR have better shower and thunderstorm coverage ahead
of the warm front over the southern Adirondacks between 05Z-09Z
with Showalter indices of 0 to -3C on the NAM and MUCAPE close
to 1000 J/kg. The warm advection and H1000-850 theta-e advection
will increase overnight with sfc dewpts rising into the 60s and
PWATS to 1.4-1.7 inches. Some brief bursts of heavy rainfall
will be possible. Lower chance pops south and east of the
Capital Region are likely tonight, as the better synoptic
forcing is north and west. Lows tonight will be in the 60s to
close to 70F in the mid-Hudson Valley and Capital District.
Friday could be an active day as combination of high moisture
content, approaching pre-frontal and main frontal zones and
positive tilted trough could allow for some training cells to
evolve. Question is overall instability and latest model trends
are less with the QPF. Yet if we are able to see breaks in the
overcast then greater instability can be realized hence the
marginal risk continued by SPC. The main threat will be from
heavy rainfall as PWATs are at or above 2" but through the day
not widespread enough for headlines at this time. We will
continue to watch and collaborate along with future upstream
trends and guidance.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Friday night, as upper level jet energy, and the low/mid level
thermal gradient slowly approach from the west, chances for
showers and thunderstorms should continue well through the night.
Locally heavy rainfall will be possible, as PWAT`s remain close
to 2 inches, especially for areas near, and to the south and
east of Albany. It will remain warm and humid, with low
temperatures only falling into the mid/upper 60s.
Saturday, still could be a few rounds of showers and
thunderstorms from the Capital Region and points south and east
in the morning, as the cold front slowly settles southeast,
while some of the remnants, or moisture associated with Cindy
rides just south/east of the frontal boundary. Locally heavy
downpours will remain possible, especially across portions of NW
CT, the mid Hudson Valley, and southern Berkshires. The main
band of showers/thunderstorms should move south/east of the
region by afternoon. However, lingering upper level energy and a
possible weak reinforcing cold front may trigger an additional
shower or thunderstorm in the afternoon, especially across the
eastern Catskills into the mid Hudson Valley. It should
gradually become less humid in the afternoon, with late day high
temperatures ranging from the lower/mid 70s across higher
elevations of the Adirondacks, to the lower/mid 80s across
valley areas within the mid Hudson Valley.
Saturday night, generally fair conditions, after any isolated
evening showers dissipate. It should be cooler, with low
temperatures mainly in the 50s.
Sunday-Sunday night, a couple of strong yet compact upper level
impulses look to track across the region during Sunday. Strong
dynamical forcing associated with these impulses could lead to
at least isolated-scattered showers/thunderstorms, although the
areas which may be affected overall could remain limited since
these systems are fairly compact. Would not rule out some gusty
winds/hail with any thunderstorms given fairly low wet bulb zero
levels and strong winds aloft, even though the tops of any
convection may remain relatively shallow/low topped. High
temperatures should reach the mid/upper 70s in valleys, with
mainly 60s across higher terrain. After any isolated convection
dissipates Sunday evening, expect clear to partly cloudy skies
to remain, with temperatures cooling into the lower/mid 50s for
many areas, with perhaps some 40s across portions of the
Adirondacks and higher terrain across western New England.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
The extended forecast will be dominated by a mean longwave mid and
upper level trough over the eastern CONUS into the middle of the
week. Cool and unsettled weather is expected into Wednesday for
early summer. Some ridging may briefly build into the the Northeast
by Thursday.
Mon-Mon Night...A deepening and amplifying H500 long-wave trough
will be setting up over the Great Lakes Region, OH Valley into the
Northeast. A series of short-wave troughs will be impacting the
forecast area migrating through the mid and upper level trough.
Heights will be falling across the region with a cold front
initially descending southward from the St Lawrence River Valley,
but will likely lift north late in the day ahead of the short-wave
trough. The 12Z GFS continues to show modest amounts of instability.
A chance of showers with a slight chc of thunderstorms was kept in
the forecast during the day. Highs will be in the upper 60s to mid
70s in most of the valley areas with upper 50s to upper 60s over the
higher terrain in the cool cyclonic flow. The showers will become
isolated to scattered at night with the loss of the diurnal heating
with lows in the upper 40s to mid 50s across the region, as H850
temps will be about 1 to 2 standard deviations below normal
according the latest 12Z GEFS.
Tue-Tue Night...The latest GFS/ECMWF/CAN GGEM have a stronger short-
wave embedded in the long-wave trough impacting the region on TUE.
At the sfc, a wave of low pressure will be lifting north of the
region towards the St Lawrence River Valley with a cold front moving
through in the late morning into the afternoon. The cyclonic
vorticity advection with some thermal advection will generate enough
synoptic lift for showers likely especially from the Capital Region
north, with high chc pops to the south. The amount of heating and
sfc destabilization is still uncertain, but there could be enough
instability with SBCAPEs in the 500-1000 J/kg for at least a slight
chc of thunderstorms in afternoon. High temps will be similar to MON
with 60s to mid 70s across the region which is about 5-10 degrees
below normal.
Wed-Thu...Much of eastern NY and western New England will still be
under the influence of mid and upper level cyclonic flow with the
trough axis attempting to move downstream. With the cold pool aloft
and weak impulses rotating around the upper low, then some
instability showers are possible across most of the region. A little
more sunshine before the pop-up showers will allow for highs in the
mid 60s to lower 70s over the higher terrain, and mid and upper 70s
in the valley locations. There are some signs of ridging building
in from the south and west Wed night-THU with heights rising across
the region based on the 12Z EC and the WPC guidance. The GFS wants
to the close the upper low over eastern New England with with N/NW
flow isolated-sct showers over the higher terrain. We trended WED
night dry, and based on a blended model approach we kept a slight
chc of showers in the valley areas in the grids during the day, and
a very low chc over the southern Adirondacks, southern Greens,
northern Catskills, and the western Mohawk Valley. Again, this day
is trending drier if the 12Z EC does not close the upper low off
like the latest 12Z GFS.
Overall, temps look below normal in the long term with pcpn normal
to above normal.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
A warm front will approach eastern NY and western New England
tonight with some isolated to scattered showers and
thunderstorms. It will move through tomorrow morning, as the
region will get into a warm sector. The cold front will approach
from the west late tomorrow afternoon into the evening with
widespread showers and a chance of thunderstorms.
VFR conditions will continue early tonight with mid and high
clouds over the terminals. Expect cigs to continue to lower to
5-8 kft AGL with the best chance of showers or thunderstorm
close to KGFL. We placed some VCSH groups for KGFL/KALB/KPSF in
the 08Z-09Z time frame. The increase of low-level moisture may
allow for some vsbys to get in the 4-6SM range with the best
chance of MVFR vsbys near KPOU. PROB30 groups were used for a
chance of thunderstorms between 11-15Z at KGFL/KPSF and 14-18Z
at KALB/KPOU. It is not clear cut, but entering the warm sector
there will be a chance of thunderstorms with MVFR vsbys and
possibly cigs for a brief time. After 18Z, VFR conditions will
return with a better chance of showers and thunderstorms close
to 00Z/FRI, but our confidence was not high enough to include in
the TAFs at this time in terms of chances of showers and
thunderstorms.
The south to southwest winds at 4-7 kts will become light and
variable tonight at KGFL/KPOU, but remain steady at KALB/KPSF.
The winds will increase from the south at 10-15 kts with some
gusts in the 20-25 kt range at KALB/KPSF in the late morning
into the afternoon. Stronger wind gusts may occur with any
thunderstorms.
Outlook...
Friday Night: High Operational Impact. Likely SHRA...TSRA.
Saturday: Moderate Operational Impact. Breezy Chance of SHRA...TSRA.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Moderate Operational Impact. Scattered SHRA...TSRA.
Sunday Night: Low Operational Impact. Isolated SHRA.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday Night: Low Operational Impact. Slight Chance of SHRA.
Tuesday: Moderate Operational Impact. Likely SHRA...TSRA.
&&
.FIRE WEATHER...
Warmer and more humid conditions will return tonight into
Friday, along with increasing chances for showers and
thunderstorms, some of which may produce locally heavy rainfall.
The showers and thunderstorms should continue Friday night,
before gradually tapering off Saturday as a cold front moves
through and south of the region. Another upper level
disturbance could trigger a passing shower or thunderstorm
Sunday.
Relative humidity values are expected to increase to between 80
and 100 percent tonight. Minimum RH values on Friday will be
around 55 to 70 percent.
Winds will shift into the south tonight at 5-10 mph. Winds on
Friday will be south to southwest and increase to around 10 to
15 mph, with gusts up to 25 mph possible.
Winds will be stronger, and variable in direction in and near
any thunderstorms.
&&
.HYDROLOGY...
A few showers will be possible well west of Albany early this
evening.
More widespread showers and thunderstorms will start to move in
tonight, and especially on Friday as a frontal system gradually
moves across the area. It will become more humid, so there is
the potential for locally heavy rainfall Friday into Friday
evening. Some urban/poor drainage flooding and isolated flash
flooding will be possible with thunderstorms. Basin average
rainfall forecast to be around a half to three quarters of an
inch, with locally higher amounts where persistent
thunderstorms occur. Showers and thunderstorm with locally heavy
downpours may linger into Saturday morning from the Capital
Region and points south and east.
Mainly dry weather then expected for Saturday afternoon with
just a few showers around, with isolated to scattered showers
and thunderstorms possible Sunday into Monday.
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.
&&
.EQUIPMENT...
KGFL airport observation has been intermittently missing again
as technicians continue to troubleshoot. We will continue to
monitor and update this statement as needed.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...KL/BGM/Wasula
NEAR TERM...BGM/Wasula
SHORT TERM...KL/JPV
LONG TERM...Wasula
AVIATION...Wasula
FIRE WEATHER...KL/JPV
HYDROLOGY...KL/JPV
EQUIPMENT...WFO ALY
forecast, please read the previous forecast discussion below.
Previous forecast discussion...
Tonight...An increasingly moist southwest flow will develop
overnight with PWATs rising to around 1.50". Surface low
pressure in the western Great Lakes will push a warm front
through the region although the forcing with this feature is
fairly weak. Best moisture and lift continues to be in the far
northern forecast area where we will keep high chance pops later
tonight with slight chance across the central and southern
forecast area. Due to mid level instability will keep the
mention of thunder. It will be mild and increasingly muggy as
dew points rise and lows range from the middle 60s to lower
70s.
Friday/Friday night...A deep southwest flow of increasing
moisture from Tropical Depression Cindy will bring PWATs to
around 2 inches by afternoon. Models have slowed the progress
of the surface cold front with passage now expected Friday
evening. Model soundings show tall/skinny CAPE and warm cloud
layer around 11k-12k feet. These are indications of potentially
very heavy rainfall with any convection. Due to a really juicy
atmosphere with plenty of clouds the amount of destabilzation
that occurs tomorrow is a big question mark. Low level shear
still looks fairly good to support severe weather but many
elements are lacking. There still is the threat for isolated
severe thunderstorms during the afternoon and evening but more
concerning is the heavy rainfall threat. Later shifts may need
to issue a flash flood watch if the event looks more certain.
Will continue with likely pops from Friday afternoon into
Friday evening then lower pops after midnight as this boundary
drops through. Highs will range in the upper 70s to lower 80s
with dewpoints around 70 making it feel rather muggy. Friday
night temperatures cool off in the lower to middle 60s.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
Remains of T.S. Cindy will pass just south of the area early
Saturday and may bring a few showers to NEPA. Later in the day,
surface trof and mid level short wave will drop into the area
from the Great Lakes resulting in scattered afternoon showers.
Weak surface ridging builds in for Saturday night and Sunday,
but yet another mid level wave passes through later in the day
some additional showers are possible, especially during the peak
heating hours with the cold pool aloft.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Unsettled weather continues into the long term with a persistent
upper low over the central Great Lakes creating instability,
especially during the afternoon hours. Solution to the problem
is still up in the air (pun intended) as the GFS and EURO come
to different conclusions on the eventual disposition of the low.
The latest GFS develops a slow moving closed low that will
linger somewhere in the NY and New England area through and
beyond the period. EURO is more progressive and would sweep the
low through as a deep but open wave by Wednesday. In any event,
it looks as though cool and unsettled weather with mainly
afternoon showers will continue through the long term.
Temperatures will average below normal, especially during the
daylight hours.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
The forecast calls for continued VFR conditions into Friday
morning, as a high-deck slowly lowers to a mid-deck. Winds will
be light overnight.
Showers and thunderstorms, some with heavy rain, will develop on
Friday. As the atmosphere moistens, MVFR ceilings and
visibilities will become more prominent. Southwest winds will
gust to 20 knots Friday afternoon.
Outlook...
Friday night...Showers and thunderstorms through Friday evening,
with associated restrictions.
Saturday - Monday...Mostly VFR, but shower/storm and brief
restriction possible.
Tuesday...Convection with restrictions.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...RRM
NEAR TERM...KAH/RRM
SHORT TERM...DGM
LONG TERM...DGM
AVIATION...DJP
Area Forecast Discussion
National Weather Service Denver/Boulder CO
744 PM MDT Thu Jun 22 2017
.UPDATE...
Issued at 712 PM MDT Thu Jun 22 2017
Convection across the area has dramatically underperformed this
afternoon into the evening. The primary reasons for weak and poor
coverage of the thunderstorms this afternoon and this evening came
about just before noon when the convective temperature was
reached across the Foothills and adjacent Plains...thunderstorms
quickly formed and developed a thick cirrus shield that overspread
much of our area. As the storms moved east of I-25 they
encountered a robust cap, and storms weakened then dissipated as
they moved further east. The cool outflows from the initial storms
and thick cirrus limited instability this afternoon and evening.
Where the models were predicting 1500+ J/kg MUCAPE, probably more
like 500 J/kg were available. Given the convective stability east
of the Continental Divide this afternoon that will continue into
the overnight hours, updates were made to the forecast...namely
eliminating any threat of severe weather and reducing PoPs overall
from chance to slight chance or less.
After 1 AM tonight the HRRR and ESRL HRRR, and the NAM all show a
cold front entering the state from Wyoming and Nebraska. They
have been consistent for the past 4-5 hourly runs. Current surface
obs across the central high Plains are showing fairly strong N/NE
flow, and there is a strong surface high over Montana moving
south. GOES-16 WV currently shows a weak short wave trough moving
south into Wyoming. Feel these are the features the high res
models are latching onto. Fully buying into the northerly frontal
surge solution will take a leap of faith given how poorly the high
res models handled today`s convective evolution. Additionally, the
global models are also overdoing precipitation tonight...so the
updates made to PoPs were to lessen them and synch the PoPs with
the timing of the front. Given all this, and assuming the frontal
passage occurs as shown in the high res models, there should be
an hour or two of light rain showers occurring behind the front
along with low clouds and much cooler temperatures. The cool
temperatures and cloud cover will continue through Friday, and
given how hot it was this week, it will feel quite cool to most of
us throughout the day.
&&
.SHORT TERM...(This evening through Friday)
Issued at 255 PM MDT Thu Jun 22 2017
Storms continues to spread west to east across the forecast area.
With the front now all the way through the area, upslope flow
continues to increase. However, the better moisture has been slow
to work its way in, so strength of storms are weaker at this point
than initially thought. More threat right now is strong outflow
winds, with hail threat increasing as the afternoon goes on.
A shortwave currently in southern Idaho into central Wyoming is
progged to push south tonight, to push additional moisture and the
cooler air in with an increase in upslope flow. Will see a
continuation of showers and storms likely through midnight, with a
possibility of seeing convection for a few hours after midnight
with the shortwave. Forecast soundings show lower levels
moistening up with stratus expected to push in, however upper
levels still remaining unstable. For now will remove mention of
thunder after midnight for the high terrain and after 3am over
the plains, with stratus spreading across the plains and into the
foothills up to about 10kft. This will create areas of fog along
the foothills and adjacent plains.
High surface pressure will remain over the Great Plains to keep
upslope into NE Colorado Friday. Clouds will likely remain over
the most of the plains to keep temperatures readings in the 60s,
a nice respite from the heat of late. Further west of the divide,
temperatures will still be cooler than today, but some instability
may allow for isolated weak afternoon thunderstorms.
.LONG TERM...(Friday night through Thursday)
Issued at 255 PM MDT Thu Jun 22 2017
Cooling trend continues through the weekend with a moist and cool
airmass in place on the plains. A cold front will move into NE
Colorado Saturday ushering in cooler air. Easterly winds will
help to keep moisture pooling into the foothills with clouds
persisting through the evening into Saturday afternoon. Model air
soundings show increased mid-level subsidence through the weekend.
Some light precipitation will be possible but expecting more
showers and closer to the foothills vs convection. The convection
potential will increase over the higher terrain for Saturday and
Sunday as conditions will be warmer and more unstable then on the
plains. Brief heavy rain, deadly lightning and small hail with
gusty winds will be possible with any convection. Temperatures
will continue to be below seasonal normals with highs in the 70s
through the weekend.
For Monday into mid week the upper level ridge will start to build
back into the Great Basin ushering in a warmer airmass for Monday
and slowly increasing temperatures through the week. With the
warming airmass...at least for Monday into Tuesday do not expect
much in the way of convection due to a stable mid level. A lee
side trough will help to increase downsloping and warming
temperatures for Monday evening into Tuesday with lows in the 60s
and highs on Tuesday reaching back above normals in the low 90s.
Chances of convection increase on Wednesday with the possibility
of breaking the cap and having some isolated storms in the
afternoon on the plains. By Thursday GFS and EC showing a front
moving in late Wednesday that could help to destabilize the
atmosphere and increase storm chances for Thursday. Will continue
to monitor to see how models time the incoming front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 712 PM MDT Thu Jun 22 2017
Convective potential has waned this evening and thunderstorms are
not expected through the TAF period. Light winds from an easterly
direction should occur this evening and into the overnight hours.
Between 10 and 11Z, expect a strong northerly push to occur
across the three TAF sites, with north winds 15-20kt with higher
gusts at DEN, and around 10-15 kt at APA and BJC. Rain showers are
possible (20-30% chance) for an hour or so behind the front and
have handled this with TEMPO groups. Low stratus development is
also a strong possibility ahead of the front in the upslope flow,
and especially after frontal passage when CIGs may drop to 010. In
precipitation CIGS may briefly drop to 006 or 008. At this time
VIS should stay up around 5 SM, but in precipitation it could
briefly drop to 3 SM. It looks like CIGS will lift with drier air
and the late June sun Friday morning, such that by 16/17Z and
beyond VFR conditions should prevail.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Schlatter
SHORT TERM...Kriederman
LONG TERM...Bowen
AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Duluth MN
636 PM CDT Thu Jun 22 2017
.SHORT TERM...(This evening through Friday)
Issued at 313 PM CDT Thu Jun 22 2017
An upper level low was over the Manitoba Lakes region this afternoon
and is forecast to move southeast through northwest Ontario toward
northeast Minnesota overnight. The low will open up as it progresses
southeast through the day Friday. The rain over northwest Wisconsin
will diminish through the evening as the frontal boundary sags south
and FGEN decreases. More showers are possible over portions of
northern Minnesota late this afternoon into the overnight period.
The HRRR has been consistent for the last several runs developing an
area of showers over western Minnesota then moving them east and
north through the evening. Area radars have yet to show any
appreciable echoes there but visible satellite imagery does show
a growing cumulus field. We will have a chance for showers into
the evening over parts of northeast Minnesota then over far
northern Minnesota through the overnight period as the low moves
southeast. Cold air advection will continue overnight and lows are
expected from the upper forties to lower fifties.
A chance for showers and perhaps an afternoon thunderstorm will
continue Friday across much of the Northland due to a weak shortwave
and enough instability present from the colder air moving in. Highs
will be below normal, ranging from the lower to middle sixties along
the International Border to the mid to upper sixties over northwest
Wisconsin.
.LONG TERM...(Friday night through Thursday)
Issued at 313 PM CDT Thu Jun 22 2017
The extended forecast continues to feature weekend chances of
showers and thunderstorms, along with some below seasonal
temperatures Saturday through Monday.
The extended period begins with a cut-off upper-level low advancing
southeast towards the Northland. An associated mid-level shortwave
trough, with a concentrated maxima of positive vorticity advection
will translate just across our southwest. The models have come into
better agreement with the position of this mid-level trough compared
to yesterday`s corresponding runs. Despite the main trough diving
south of the area, a corridor of better mid-level isentropic lift
and 850-700 mb Q-vector convergence is progged on the northern
periphery of the trough. Chances of thunderstorms will mainly be in
the afternoon and early evening since that will be when the better
instability will be in place. MLCAPE values of up to 500 J/kg will
be possible when the low-level lapse rates steepen, thanks to low-
level diabatic heating. No severe weather is expected as the
instability and deep layer shear just looks too low to support any
substantial threat. A lingering secondary shortwave will continue
chances of showers into Sunday, with another round of thunderstorms
possible for Sunday afternoon. The best chances of storms will be
over northwest Wisconsin, where the better instability should be in
place. Again, no severe weather is expected. Due to this trough
pattern and persistent northwesterly flow over the region, cooler
air advection will take control. This will lower temperatures mainly
from Saturday through Monday, with highs in the lower to mid 60s.
Temperatures will start to increase Monday and Tuesday as winds turn
more southerly.
A mid-level ridge will develop Monday morning into early Tuesday
over the Great Plains region, which should bring mostly dry and
warmer conditions. This should bring some light winds and mostly
clear skies, so it could be a pretty chilly morning on Monday,
perhaps even better radiational cooling for Tuesday morning. Did
lower the temperatures for Tuesday below the consensus blends a bit
to better correspond to this radiative cooling, with lows into the
lower to mid 40s both mornings.
More showers will ramp up again Tuesday night into Wednesday morning
as a region of upper-level divergence develops out of the
Intermountain West. The GFS is showing some stronger lift in the mid-
levels as well, so some good forcing could be in place for some
showers and thunderstorms through the day Wednesday. It`s possible
that this will bring the best chance of strong thunderstorms, as
instability looks to be much higher, but it`s still too far to
really nail down a solution, especially when the magnitude and
placement of the axis of instability varies between the
GFS/CMC/ECMWF models. Showers and storms could continue into
Thursday as another potent shortwave moves in closely behind the
Wednesday morning system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 633 PM CDT Thu Jun 22 2017
A weak disturbance will move across the Northland this evening,
generating some isolated showers and possibly even a thunderstorm.
The best chance will be in the northern TAF sites. Another front
will drop southeastward out of Canada late tonight and on Friday.
This front will bring cooler and more moist air, which will result
in areas of MVFR CIG, especially north. KDLH and KHYR should
generally remain VFR throughout the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 52 66 49 63 / 10 20 10 40
INL 50 62 48 60 / 30 40 40 50
BRD 53 65 47 64 / 10 10 0 30
HYR 52 69 49 64 / 20 20 10 40
ASX 53 69 50 64 / 10 20 10 40
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...Melde
LONG TERM...JTS
AVIATION...DAP
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
942 PM EDT Thu Jun 22 2017
.UPDATE...
It has been an active evening as cluster of severe thunderstorms
lifted northward through a good portion of the southern Detroit metro
area. Initial cell appeared to get mid to upper level support by
gravity wave forcing to the south of Toledo. The thunderstorm quickly
latched onto the main 850-700mb gradient of tropical moisture and
provided the perturbation to drive additional thunderstorm activity
northward along a mature outflow boundary. Overall, hi-resolution
models have done a poor job resolving this initial thunderstorm
activity within the broad anticyclonic ridging and confidence remains
lower than average. With that stated the signal points to activity
migrating northward throughout the remainder of the evening as the
main equivalent potential temperature gradient lifts northward and
merges with the synoptic scale cold front now over sections of
northern Lower Michigan.
Uncertainty remains high with specifics, but expectations are for
shower and thunderstorm activity to become more organized over the
northern cwa, north of I 69 primarily between 02-09Z tonight.
Activity should then transition south again, south of the I 69
corridor between 09-14Z Friday morning. Severe threat appears to be
waning as model soundings show loss of diurnal heating significantly
compromising lower level lapse rates. One factors in current
activity overturning the air mass, and confidence increases that high
static stability will exist through a deep layer between 2.0 and 9.0
kft agl. Current SPC RAP based shows just a pocket of MLCAPES of
between 1000-1250 J/KG where current thunderstorms reside. Expecting
this instability to lessen considerably during the next hour or two
to around 500 J/KG for the course of the overnight. Deep layer shear,
particularly closer to the front across the north will remain good
enough for storm organization so will continue to monitor. However,
signs point to the severe threat lowering considerably. The main item
to watch for is heavy rain potential with training of elevated
thunderstorm activity. Right now it appears best potential for this
heavy rainfall will be north of I 69.
Inherited grids are in reasonably good shape and little changes are
anticipated.
&&
.PREV DISCUSSION...
Issued at 811 PM EDT Thu Jun 22 2017
AVIATION...
Cluster of severe thunderstorm activity lifting northward through
Detroit is being forced along the lead gradient of 850-700mb
tropical moisture. The thunderstorm activity will continue for the
first hour or two at Detroit terminals before lifting northward with
time tonight. There is a high amount of uncertainty with how tonight
will play out. Hi resolution guidance this afternoon missed
completely on this warm sector thunderstorm development within
overwhelmingly anticyclonic flow trajectories. The idea right now is
that tstorm activity should transition northward to possibly between
the I 69 corridor to Tri Cities sometime after 02-03Z this evening.
This activity should then continue (expected to be elevated and
weaker) throughout much of the night along a slowly sagging cold
front.
Shower and tstorm potential will then pick up towards daybreak again
around the Detroit Metro area before transitioning southward over
portions of Ohio by late morning Friday.
//DTW THRESHOLD PROBABILITIES...
* High for thundestorms early at start of period, low for much of
tonight and medium for 09-13Z Friday.
* High confidence in ceilings aob 5kft tonight into Friday Morning.
PREV DISCUSSION...
Issued at 353 PM EDT Thu Jun 22 2017
DISCUSSION...
Warm and humid southwest flow will be firmly established over lower
Michigan during late afternoon through tonight. Temperatures will
come down from highs near 90 and heat index in the mid 90s but it
will remain warm and muggy through the night. This will leave
convective trends as the main concern beginning with scattered late
day/early evening development followed by storms arriving from the
Midwest frontal system during the night into Friday morning. Passage
of the front through SE Michigan by early to mid Friday afternoon
will then bring cooler and less humid air into the region for the
weekend.
Afternoon satellite imagery and hourly mesoanalysis/surface
observations indicate warmer and more humid air moving in through
the boundary layer in southwest flow over the region. This is
occuring under a relative theta-e minimum that is a result of both
warmer air moving in aloft that is not quite as moist and possibly
some subsidence trailing morning convective activity. The warmer air
is at least temporarily capping off additional shower/storm
development through peak heating. There is also observational
evidence of deeper moisture moving in from the Ohio valley
associated with the northern fringe of TD Cindy. It is this moisture
surge that is shown to produce late afternoon/early evening
convection over northern OH/IN developing into lower Michigan during
the evening. This activity will occur ahead of the convection
upstream over the Midwest that is being forced along and ahead of
the cold front/outflow combination and which is expected to progress
eastward into SE Michigan during the night. Both rounds of storms
will share a similar near storm environment. Model derived ML CAPE
and shear projections best supported by observations are in the
range of 1000-1500 J/kg along with marginal bulk shear around 30
knots. This combination will be capable of some multicell structures
with otherwise moderate mid level wind speed that could produce some
near severe wind gusts in line with the borderline slight/marginal
SPC outlook that covers SE Michigan. Locally heavy rainfall will
likely turn out to be the main concern as PW ramps up to near 2
inches overnight. Individual convective cells will be moving quickly
enough but there will be a tendency for some training lines that
will have localized potential for flooding of prone areas.
Numerous to widespread showers/storms that spread into the region
overnight will tend to break up as they will be ahead of the surface
front and upper level wave toward Friday morning. As this convection
continues to dissipate during the morning, there will be another
narrow window of opportunity for new development along the cold
front before peak heating and before it boundary exits SE Michigan
during early to mid afternoon. Passage of the front will then open
the door on cooler and less humid air Friday night into Saturday.
Some weak instability showers will be possible Saturday afternoon
and evening but the large scale pattern does not look very
supportive. Neutral southwest flow aloft downstream of the main
upper trough and a featureless westerly low level flow might support
isolated to scattered coverage of light showers during peak heating.
The region will remain in longwave troughing to close out the
weekend and into the beginning of next week. This will allow for
chances for unsettled weather through this time period before things
start to dry out by the middle of the week. Longwave ridging starts
to build in on Tuesday as surface high pressure takes control over
the Great Lakes region. As far as temperatures are concerned, highs
will be noticeably cooler on Sunday and Monday as highs hold around
70 degrees. Temps then rebound back towards the upper 70s though
the end of the extended forecast period.
MARINE...
Warm and moist southerly flow this afternoon, but topping out around
20 knots for the most part. Scattered showers and thunderstorms
around late today and this evening, with more solid line of showers
and embedded thunderstorms later tonight with cold front, which will
pass through the Central Great Lakes tomorrow. Winds will shift to
the west-northwest behind the front and remain from that general
direction through the weekend with wind speeds under 20 knots. An
unseasonably cold airmass this weekend will bring the chance for
light showers across most of Lake Huron.
HYDROLOGY...
An influx of moisture will trigger scattered showers and
thunderstorms late today and this evening, with more widespread
shower and thunder activity with cold front late tonight into early
tomorrow morning. All told, localized rainfall amounts may reach an
inch or more, especially from around Flint on north into the Saginaw
Valley, where storms expected to arrive earlier and are able to
utilize the waning daytime instability. Urban and small stream
flooding will be possible with the stronger activity.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
UPDATE.......CB
AVIATION.....CB
DISCUSSION...BT/SP
MARINE.......SF
HYDROLOGY....SF
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
931 PM EDT Thu Jun 22 2017
.SYNOPSIS...
High pressure will move away from the region tonight. Tropical
moisture from the remnants of Cindy...and an approaching
frontal system will result in showers and thunderstorms Friday
into Friday Night. A series of surface troughs or weak cold
fronts will cross the area this weekend into early next week
bringing us the chance of showers from time to time...especially
over central and northern areas.
&&
.NEAR TERM /THROUGH FRIDAY/...
926 PM Update: Have made minor changes to the forecast this
hour...slowing precipitation arrival just a tad...but boosting
cloud cover based on evening satellite imagery. Am watching
shower activity moving east near KRME/KUCA along the elevated
warm front and expect this to make a run at the area after
midnight. Still...best forcing waits until well after midnight
with best confidence in the north...where PoPs were upped based
on latest HRRR simulations which line up well with upstream
trends and movement of the warm front. Temperatures nudged up a
bit given current observations...increasing cloud cover...and
GFS LAMP trends.
552 PM Update: Going forecast in good shape with only minor
adjustments needed for temperatures. Expect the evening to
remain dry based on upstream radar evolution and recent HRRR
simulations with shower and embedded thunder chances arriving
from the west after midnight.
Previous discussion below...
A weak 500 mb ridge moves across the CWA tonight, which should
help to keep the evening dry, for the most part. Cannot rule out
a shower or sprinkle in the north and west, but this will
probably not produce enough to measure if it occurs at all.
Clouds will thicken from the west this evening. Very latitudinal
stretched trough to our west will bring some WAA across the CWA
tonight, with the better chance of showers after midnight and
in the nrn and western zones. Some elevated instability as well,
so cannot rule out some thunder, but all in all nothing
significant overnight, and some places will see nothing at all.
Temps will fall this evening, but increasing low level moisture
and clouds will likely stall the the temp drop around midnight
or so, and lows will range from the mid to upper 50s in the
north and east, to the low to mid 60s in southern NH and along
the coast.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH 6 PM FRIDAY/...
The big question for Friday is whether any part of the sfc CWA
can break into the warm sector and get some sun and heating. The
warm front should be exiting to the north in the morning,
before secondary low forms on the triple point just N of New
England, which would allow some southern zones to break out
given decent SW flow. This would destabilize the atmosphere
enough to produce TSRA, which would open doors for training of
cells, producing very heavy rain, and potential for severe
storms developing in the afternoon. Since best dynamics will lag
a little behind the warm sector, and its questionable how
unstable things get given clouds, will not highlight any severe
at this time. Heavy rain, however is a better bet, with very
moist air, some of it from the remnants of tropical storm Cindy,
will produce PWATS of around 2 inches. So, could still see heavy
downpours late in the day into the evening, when the better
dynamics aloft move through ahead of the front. Highs are a
tough forecast, and dependent on if and when any locations see a
decent amount of sun, but they will range from the low to mid
to 70s in the mid coast area, where onshore flow will hold for
most of the day, to the low to mid 80s in srn NH and the CT vly,
where the SW flow will be warm and there will be the chance for
some sun.
The from looks to move through late Friday night, and will
follow the best dynamics as well, so while showers will be
possible through the night, the threat for torrential downpours
should diminish around and after midnight. It is unlikely to
see the front at the sfc, until mixing begins Sat morning, so
expect humid conditions to linger with lows in the 60s, and
mostly in the mid to upper 60s outside the mountains.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Global models in general agreement over this period. A cold
front will be located over the coastal plain early Saturday.
This could result in a few early morning showers. As the front
pushes offshore expect drier air to move in during Saturday. A
couple of mountain showers may develop in a developing NW flow.
Coastal areas will see a downsloping wind resulting in dry
weather.
On Sunday the NW flow will continue. A short wave of vorticity will
approach which could produce a few showers...again the best chances
will be over northern and mountain areas. This pattern will persist
on Monday. Late Monday low pressure will develop along the Mid
Atlantic Coast. The most recent runs of the models still track
this low offshore but hold back some troffiness over New England
which would result in a period of rain or widespread showers
for Tuesday. As the low continues to move NE the 500 mb trough
sharpens and looks to keep the area unstable with the threat of
at least a few showers and thunderstorms Wednesday and
Thursday.
Temperatures will start off normal to slightly above normal
Saturday but will become normal to slightly below normal Sunday
through Thursday.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term...
Summary: A warm front will lift north across the region tonight
with an increasing chance for showers and a few thunderstorms after
midnight. A warm and very moist airmass will then yield
an increasing risk for showers and thunderstorms by the
afternoon hours on Friday under southerly flow. A cold front
arrives from the west Friday night with continued chances for
showers and thunderstorms.
Restrictions: Generally VFR through tonight with some threat for
temporary restrictions primarily HIE/LEB after midnight in a shower
or embedded thunderstorm. On the day Friday...VFR conditions should
dominate all locations through the morning...but by
afternoon...expect increasing shower and thunderstorm coverage
to result in some occasional MVFR/IFR restrictions...esp at
HIE/LEB/AUG. Also...marine layer will likely work into RKD with
IFR CIGS/MVFR VSBYS. Shower/thunderstorm coverage will decrease
Friday night...but with moist airmass still in place...expect a
good amount of haze and fog...with locally dense fog possible
depending on how much rain we realize.
Winds: Winds less than 5kts overnight before becoming southerly on
Friday and increasing to 10g18kts. Southerly winds continue Friday
night but diminish to less than 10kts.
LLWS: There is some risk of LLWS in the vicinity of RKD after 18Z
Friday with low level jet overriding stable air off the ocean.
Thunder: Some risk of an isolated thunderstorm through daybreak
Friday for LEB/HIE. Thunder threat will increase all areas for the
day Friday...particularly afternoon and evening...but remain
greatest at HIE/LEB...with thunder threat diminishing with the loss
of daytime heating Friday night.
Long Term... Mostly MVFR to VFR conditions south
of the mountains Saturday though Monday although brief IFR
possible in any showers. MVFR to IFR conditions over the
mountains in clouds and scattered showers. A better chance of
IFR conditions on Tuesday as more widespread showers/rain is
expected.
&&
.MARINE...
Short Term...SCA issued for SW winds Fri afternoon into early
Saturday morning. Winds will likely peak Sat evening.
Long Term...
Waves and winds to remain below SCA levels. Visibilities may
become reduced in rain on Tuesday.
&&
.TIDES/COASTAL FLOODING...
Astronomical high tides will continue through the weekend with
the possibility of nuisance flooding Saturday night at high tide
which will occur at 12:05 am Sunday Morning at Portland and
12:16 am at Portsmouth/Fort Point.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 2 PM Friday to 8 AM EDT Saturday for
ANZ150-152-154.
&&
$$
SYNOPSIS...
NEAR TERM...Arnott/Cempa
SHORT TERM...Cempa
LONG TERM...Lulofs
AVIATION...Cempa
MARINE...Cempa/Lulofs
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Houston/Galveston TX
903 PM CDT Thu Jun 22 2017
.UPDATE...
At 01z, the remnants of Cindy was located over southern Arkansas.
A few showers lingered over the extreme eastern zones this evening
but these showers look like they are in the process of
dissipating. Can`t rule out a few isolated showers over the
eastern half of the region, closest to Cindy, so will maintain 20
PoPs. Low level moisture has increased and overnight lows are
going to be on the warm side. 00z soundings show 850 temps have
warmed at CRP and are near 24 C. The CRP sounding still looks dry
although PW values have increased to 1.50 inches. LCH shows a
moist profile with an 850 temp of 18 C. Fcst soundings for Friday
show 850 temps near 22 C over Houston so max temps look warmer.
Low level moisture will make it feel even warmer with HI values
between 103 and 110 degrees. Looking ahead to Saturday, a slow
moving cold front coupled with PW values near 2.20 inches should
be a favorable environment for shra/tsra. The slow movement favors
some locally heavy rain over parts of the region. Previous
forecast has most of this covered nicely. Have tweaked hourly
grids to match obs but otherwise no changes are needed. 43
&&
.PREV DISCUSSION... /ISSUED 626 PM CDT Thu Jun 22 2017/
AVIATION...
Radar shows some potential for feeder bands into TD Cindy
affecting KIAH, KCXO and KUTS through about 02Z. Chances go down
through the mid and late evening. MVFR looks likely to develop
between 06Z and 09Z. The ceilings should lift to VFR between 16Z
and 18Z on Friday. Also expect winds to pick up as well. The Texas
Tech WRF and HRRR both show some potential for isolated showers
during the afternoon from KIAH eastward.
40
PREV DISCUSSION... /ISSUED 301 PM CDT Thu Jun 22 2017/
DISCUSSION...
Remnants of Cindy continue moving into far nw LA this afternoon.
As Cindy continues to move newd tonight, she will leave an
elongated axis of low level convergence and abundant moisture in
her wake across southeast TX. Will keep chance to slgt chance PoPs
running accordingly across eastern counties tonight with some
hint in the short range guidance that we could see showers develop
near the coast/bay newd. All in all, we expect conditions to
continue improving from west to east with gradual reduction in
winds and showers overnight. However, it will remain quite mild
with min Temps well in the 70s /lower 80s along the coast/ given
the rich tropical moisture still in place.
This will help set the stage for a very hot and muggy Friday.
While forecast max temps are not out of the ordinary in the upper
80s near the coast to mid 90s inland, combination of tropical dew
points will boost heat indicies significantly. HIs will get well
into the lower to mid 100s by early afternoon nearly areawide and
could approach or briefly exceed advisory conditions for some
spots in the afternoon. Fortunately south winds will remain in the
10-15 mph range, especially near the coast, which will help some.
Pattern will settle into a very unstable regime with rain chances
increasing into the weekend as a cool front moves into the region
and stalls. This will keep chance to good chance of showers Sat
through Mon. At least the rain chances and clouds will reduce the
heat a bit through the weekend, before we settle back into a more
typical summer pattern next week.
Evans
MARINE...
Winds in the wake of Cindy are backing through west on their way to
southerly. We are entering a relatively lull in the winds, but with
the pressure gradient expected to tighten back up, winds back up to
around or a little above 20 knots is expected. Because of this, have
extended the small craft advisory through the morning. Winds and
seas will slowly diminish through the weekend, but periods of
moderate onshore winds can be expected into early next week.
Tides are still elevated as winds are somewhat slow to come down,
but now only in the neighborhood of 9 inches to a foot above normal.
Because of this, low water in Upper Galveston Bay is likely not so
much a concern. Indeed, the above normal levels may be a continued
focus around high tide tomorrow morning, but at this time don`t
expect it to be quite high enough to cause significant troubles.
Luchs
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 76 95 77 88 73 / 10 10 30 50 30
Houston (IAH) 77 92 78 88 75 / 30 20 30 60 40
Galveston (GLS) 82 87 81 87 79 / 30 20 30 40 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 7 AM CDT Friday for
the following zones: Galveston Bay...Matagorda Bay.
Small Craft Advisory until 7 AM CDT Friday for the following
zones: Coastal waters from Freeport to the Matagorda Ship
Channel out 20 NM...Coastal waters from High Island to
Freeport out 20 NM...Waters from Freeport to the Matagorda
Ship Channel from 20 to 60 NM...Waters from High Island to
Freeport from 20 to 60 NM.
&&
$$
Discussion...43
Area Forecast Discussion
National Weather Service Lincoln IL
914 PM CDT Thu Jun 22 2017
.UPDATE...
Issued at 910 PM CDT Thu Jun 22 2017
The primary concern the rest of the night is the coverage and
timing of the storms as the cold front pushes southeast across
Illinois. The earlier evening showers have diminished to a few
sprinkles east of Champaign, near I-70, and approaching toward
Galesburg. Pre-frontal showers are expected to fill after 06z/1am
north of I-72. However, storms will be mainly confined to closer
to the cold front as it reaches our NW counties by 07z-08z. The
front will progress southeast the rest of the night, reaching near
I-70 by 13z/8am. A narrow corridor of instability will progress
southeast ahead of the front, but with very weak wind shear, no
severe storms are expected. SPC removed all Slight Risk from
Illinois, and Marginal Risk is only N of Peoria to El Paso. With
the very moist boundary layer, very high rainfall rates could
occur with any stronger storms. Flooding could develop in areas
susceptible to floods.
Showers and storms on Friday will become confined to areas mainly
east of I-55, and especially along and south of I-70, in closer
proximity to the passage of the remnant low from TS Cindy.
Updates this evening were mainly to fine tune timing in the PoP/Wx
forecast. Minor updates were done to hourly temps/dewpoints,
otherwise the forecast database was generally on track. Updated
information is already available.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 255 PM CDT Thu Jun 22 2017
A warm/moist airmass is in place across central Illinois this
afternoon...with 19z/2pm temperatures in the 80s and dewpoints in
the lower 70s. Deep-layer moisture associated with the remnants of
Tropical Storm Cindy continues to flow northward from the Gulf
Coast, allowing isolated showers to develop east of the I-55
corridor. HRRR has been consistently showing these showers becoming
more numerous over the next few hours, especially south of I-70.
Current mesoanalysis shows SBCAPEs of less than 1000J/kg across the
SE KILX CWA, so only isolated thunder is anticipated late this
afternoon/evening. Meanwhile further northwest, a cold front
extending from Lake Superior southwestward to Nebraska will begin to
drop into the area late tonight. Models are in fairly good
agreement that a line of thunderstorms will develop within a narrow
corridor of favorable instability/shear across Wisconsin/northern
Iowa late this afternoon...then will slowly drop southeastward into
central Illinois tonight. Consensus keeps this activity northwest
of the CWA until after midnight: however, the 12z WRF-ARW is
slightly faster and brings storms into the northwest counties
shortly before midnight. Have adjusted PoPs to keep low chance
going through the evening along/east of I-57 where deep-layer
moisture will be most prevalent. Further west, have kept the I-55
corridor dry...and have brought chance PoPs into the Illinois River
Valley after 03z. Best rain chances will arrive overnight as the
line of storms tracks/spreads southeast. While storms may initially
become strong to severe across Iowa, they will be losing daytime
instability as they come into the CWA overnight, with MUCAPE vales
decreasing to 1500-2000J/kg. Wind shear will be quite weak, so
think as instability wanes...so will the storms. Could potentially
see a few non-severe wind gusts across the N/NW between midnight and
4am, but the overall trend will be for the storms to weaken.
Cold front will sink southward through central Illinois on
Friday, bringing scattered showers and thunderstorms. Have
lingered rain chances through the morning, with the convection
dropping south of I-70 by late afternoon. High temperatures on
Friday will range from the middle to upper 70s across the SE
counties where cloud cover and rain will persist...to the lower
80s further northwest where sunshine will return during the
afternoon.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 255 PM CDT Thu Jun 22 2017
Cold front will sink southward into the Ohio River Valley Friday
night, allowing a much cooler/drier airmass to settle into the
region over the weekend. A series of short-waves dropping out of
Canada will carve a significant trough over the Great Lakes. While
most of these weak features will remain well to the north, one may
come close enough to trigger widely scattered showers across the
north Sunday afternoon. Have included slight chance PoPs
along/north of a Galesburg to Chenoa line accordingly. As the flow
becomes increasingly cyclonic, showers may also be possible across
parts of central Illinois Monday afternoon: however, with surface
high pressure over the region...have opted to leave them out of the
forecast for now. Main story Saturday through Tuesday will be the
cool temperatures, with highs remaining in the 70s and overnight
lows dropping into the lower to middle 50s.
The upper trough will lift northeastward by the middle of next
week...replaced by a zonal or perhaps even slightly southwesterly
flow aloft. Degree of weak ridging that develops over the Midwest
in the wake of the trough remains in question, thus the timing of
the next significant rain chance is also somewhat uncertain. The 12z
GFS features a stronger ridge and thus a slower eastward progression
of the next cold front until next Thursday. Meanwhile, the GEM is
quite a bit faster and brings rain into Illinois as early as during
the day Wednesday. With the ECMWF/GFS both trending slower, think
this is the way to go. As a result, have kept Wednesday dry...with
PoPs coming back into the picture Wednesday night into Thursday.
With rising upper heights, temperatures will climb back into the 80s
by Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 659 PM CDT Thu Jun 22 2017
Showers have been decreasing early this evening in the warm
sector across central Illinois. Steady southerly winds are pumping
low level moisture into the area, from the remnants of TS Cindy.
However, the coverage of precip from that system should remain SE
of the TAF sites until later in the day tomorrow. The initial
forcing for showers/storms will come with a cold front later
tonight. High resolution guidance still show a consensus that
storms will arrive after 06z/1am near PIA, and then progress to
the southeast in a line, affecting the remaining TAF sites through
13z/8am Friday morning. A narrow corridor of instability is
expected to precede the front, and a few stronger storms could
reach as far southeast as PIA. However, storm intensity should
steadily weaken as the front progresses southeast of PIA.
Cloud cover could drop from MVFR to IFR as the front moves across
Illinois, with a few storms possibly even producing brief LIFR
conditions. Have not included any tempos for those conditions yet,
and kept MVFR in the prevailing weather. Will monitor closely for
a stratus IFR layer near and just behind the front.
Winds will remain southerly the first 6-8 hours of this TAF
period, then begin to shift around to the southwest and eventually
W-NW behind the cold front. Wind speeds early this evening could
linger at 10-15kt, but prevailing winds should remain 10kt or less
for later tonight and tomorrow morning. Increased mixing Friday
afternoon will push winds back into the 10-15kt range.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Indianapolis IN
1015 PM EDT Thu Jun 22 2017
.UPDATE...
The AVIATION Section has been updated below.
&&
.SYNOPSIS...
Issued at 130 PM EDT Thu Jun 22 2017
High pressure est of Indiana will exit the area tonight. A
tropical low pressure system over the lower Mississippi Valley
will surge northward tonight...bring rain showers to Central
Indiana for late tonight and Friday. Heavy rain will be possible
with some of the rain showers as the low moves through the Ohio
valley on Friday.
As the low departs on Friday night...dry weather is expected to
return to Central Indiana for the weekend as cool high pressure
settles across the Great Plains. This will result dry weather for
the weekend.
The large high will remain the dominate weather feature for much
of the next work week. This will keep mainly dry weather with
below normal temperatures through next week.
&&
.NEAR TERM /Overnight/...
Issued at 930 PM EDT Thu Jun 22 2017
Scattered showers expected to linger over the southern zones for a
couple more hours as a mid level vorticity lobe drifts northeast
through southern Indiana.
Better threat for shower and thunderstorm activity expected to
develop during the pre dawn hours of Friday, as a southwesterly low
level jet of 35-40 kts begins to interact with a frontal system
dropping south through the Great Lakes.
Current forecast handles this idea well, with the highest PoPs
before dawn. Increased the wind forecast a bit based on current
observations.
Previous discussion follows.
Surface analysis early this afternoon shows Low Pressure in place
across Louisiana. Warm and moist southerly flow was spilling
northward into the Ohio Valley ahead of the low pressure system.
GOES16 shows plentiful moisture streaming northward ahead of the
low. Meanwhile to the north...a cold front stretched across
Western Wisconsin and Iowa to Nebraska...progressing
southeastward. These two systems will be on a collision course for
the Ohio Valley Tonight and Friday.
Forecast soundings and Time Height remains mostly dry this evening
across Central Indiana. Models suggest a slow and steady
saturation of the column through the evening hours which should
just be increasing clouds. However...overnight...stronger lift
arrives as seen within the mid levels...particularly across the
southern half of Indiana. Lower level Q vectors also indicate
good convergence developing late tonight and HRRR suggests precip
arriving from the southwest associated with the low. Furthermore
as the front arrives in the area front the northwest late
tonight...and interacts with the warm and moist air mass across
Indiana...precip chances will continue to increase. Forecast
soundings by 12Z show deep saturation with very high pwats over 2
inches.
Thus summing up will try and keep evening dry across Central
Indiana...but trend pops toward 100 overnight...particularly
across the south. Pops will be considerably lower farther north as
interaction with the tropical air mass will be less at those
locations. Given the expected rain and ongoing warm air advection
will trend lows toward expected wet bulb temps.
&&
.SHORT TERM /Friday through Sunday/...
Issued at 130 PM EDT Thu Jun 22 2017
Ample dynamics will be in place on Friday for rain...some of which
could be heavy at times. The GFS suggests the approach of the
tropical low...reaching western Kentucky by late afternoon. Warm
and moist southerly flow will continue to stream into the Ohio
valley on Friday. Models continue to suggest excellent lower level
Q vector convergence. Forecast soundings show deep saturation and
Time heights also show excellent lift...particularly across the
southern half of the state. Forecast soundings also show pwats
remaining at or near 2 inches through much of the afternoon. Thus
given the dynamics and available moisture will include a FLASH
FLOOD WATCH for the southern parts of Central Indiana. Given the
expected rain...will trend highs cooler than MAVMOS.
GFS and NAm suggests the upper flow keeps a broad yet shallow
trough in place aloft on Friday night through Sat least sunday
across Indiana and the Great Lakes. This flow aloft will help to
quickly usher the tropic low east of the Ohio valley on Friday
Night. Cool and dry northwest surface flow will replace previous
flow on Friday Night and continue into the weekend. Forecast
soundings and Time height show rapid drying on Friday night as the
Low and associated forcing departs. Thus may keep a small pops on
Friday night...mainly across the southeast as the system
departs...however most of the area will remain dry. Given the
change in air mass...will stick close to the blend on lows.
Saturday through Sunday should remain dry. forecast soundings show
a dry column. Convective temperatures appear reachable...however
a mid level inversion that appears to be present should prevent
any deep cumulus growth. A the weak broad trough will remain in
place aloft...but organized forcing fails to be seen and moisture
remains lacking with NW flow. Thus will trend toward partly clouds
this period. Given the expected cold air advection and...may
trend temps cooler than blends.
&&
.LONG TERM /Sunday through Wednesday/...
Issued at 400 AM EDT Thu Jun 22 2017
Models continue to trend toward a drier forecast for the extended
period. The only chances for a few showers and thunderstorms will be
on Sunday and Monday afternoons, mainly over the northern counties,
as a few upper waves move through the area. Otherwise, expect dry
conditions throughout the extended period with a gradual warming
trend. Highs will start out in the 70s on Sunday and Monday,
eventually topping off in the low to mid 80s by Wednesday.
Meanwhile, overnight lows will increase from the mid 50s on Sunday
night to low/mid 60s by Wednesday night.
&&
.AVIATION /Discussion for the 230300Z KIND TAF Update/...
Issued at 1015 PM EDT Thu Jun 22 2017
Shower activity just about done for now at the KIND terminal,
based on radar loop. Previous discussion follows.
Scattered showers expected in the vicinity of the terminals
through about 230200Z as a mid level vorticity lobe drifts
northeast through southern Indiana. Lapse rates rather poor, so
sustained lightning activity not expected.
Better threat for organized shower and thunderstorm activity
expected to develop over the terminals during the pre dawn hours
of Friday, as a southwesterly low level jet of 35-40 kts begins to
interact with a frontal system dropping south through the Great
Lakes. IFR visibility restrictions probable in the heavier
precipitation areas at this time.
Otherwise, MVFR ceilings 015-030 should gradually spread in from
the south this evening. Ceilings may drop into the IFR category by
the pre dawn hours under sustained warm and moist advection.
Surface gusts 18-20 kts early this evening should diminish, with
winds settling to 170-190 degrees at 9-12 kts later this evening.
Winds should gradually veer during the pre dawn hours of Friday
to 200-220 degrees by sunrise.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from Friday morning through Friday evening for
INZ052>057-060>065-067>072.
&&
$$
SYNOPSIS...Puma
NEAR TERM...Puma/JAS
SHORT TERM...Puma
LONG TERM....TDUD
AVIATION...JAS
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
933 PM CDT Thu Jun 22 2017
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
TD Cindy was noted spinning over southwest Arkansas and is
expected to track northeast through the night. The pressure
gradient around Cindy was still resulting in gusty southeast to
south winds across the CWA. These winds will continue through the
night with the strongest winds still expected across the northwest
most zones. Water vapor imagery has continued to show dry slotting
over the eastern half of our CWA with the 18Z and 00Z JAN sounding
showing a PWAT less than 1.7inches. This has limited convection
across our area this afternoon and into this evening. Local radars
still showed banded pcpn across the region. Considering the low
level shear a brief tornado will remain possible in the bands that
develop the remainder of the night but chances are low and the
current Tornado Watch will be allowed to expire with no additional
watches anticipated. The potential for locally heavy rain will
exist within the banded pcpn as well so wl continue the Flash
Flood Watch that is in effect. /22/
Prior discussion below:
This Evening through Friday: Rain bands associated with Tropical
Depression Cindy continue to pivot across our forecast area this
afternoon, bringing periods of heavy rainfall and gusty winds. A
Slight Risk for severe weather continues across the entire area
into early tonight due to the threat for damaging wind gusts as
well as brief spin-up tornadoes. Moderate amounts of instability
and strong low-level wind shear have resulted in decent spin even
in deeper rain showers without lightning. Despite a "dry slot"
wrapping around Cindy and across the central portions of our area,
adequate moisture has overspread even these areas (PWAT > 1.9
inches per RAP analysis) to make showers and storms into efficient
rain makers. Therefore we will continue the Flash Flood Watch
into tomorrow and keep a mention of Limited to Elevated flooding
threat in the Hazardous Weather Outlook. The heaviest rain
overnight tonight will likely be confined to northeast Louisiana,
far southeast Arkansas, and northwest/north-central Mississippi
near the core of the Tropical Depression. Given the recent rounds
of rainfall, flash flooding as well as creek and river flooding
will be possible wherever heavy rain falls on wet ground. Daytime
heating tomorrow could also lead to some marginally severe
thunderstorms developing over mainly the Golden Triangle and
surrounding areas as Cindy`s remnants are lifted northeastward out
of our region. /NF/
Friday night through Thursday. The remnants of Cindy will continue
to impact the area through the weekend. Cindy was not moving very
quickly to the north, but models continue to show the system into
Kentucky by Friday afternoon. However, with the area still to the
east, the risk for severe storms will continue into Friday
evening. Also, the area was in a dry slot and saw a good amount of
sun this afternoon. Low level wind shear and plenty of moisture
helped to support thunderstorm development. By Friday evening, the
trough axis will be lagging behind and low level winds will not be
that bad, so the potential for strong storms and maybe some severe
seemed ok for the northeastern portions of the rain. Trees were
falling across the region in sub-severe winds due to saturated
ground. Will likely see more of the same in heavily wooded areas
in the northeast sections of the CWA. Widespread heavy rainfall
has not occurred with this system, but waves of downpours was
causing flooding, so will maintain the flash flood watch through
the Friday evening. Wanted to monitor activity through tonight
before extending the watch into Saturday. Models show the area of
greatest rainfall being over the Delta before shifting south and
east in the evening. The lagging trough axis associated with Cindy
will be absorbed by an approaching cold front and be the focus
for shower and thunderstorm activity for much of Saturday.
Rainfall amounts were not great, but another inch of rain on top
of what is out there will aggravate flooding. High pressure moves
in quickly on Sunday and helps push convection to the coast.
Another front sweeps across the area with little impact before a
1023 high settles over the mid-south and keeps the area dry from
Tuesday into Thursday. As the ridge shifts east, there may be some
activity skirting around the ridge that moves into the southwest.
going into the weekend.
Temperatures will be mild, slightly below normal following the
cold front. A few days of sun will bring some much needed drying
to the region.
&&
.AVIATION...
00Z TAF discussion:
Rainbands from Cindy are still passing across the area this
evening...but dry slotting has allowed clouds across some
terminals to scatter out this evening. VFR will be common as we
start the 00Z TAF...but as rainbands approach terminals we may
have to adjust with amendments for an hour or so TS and vis
conditions. MVFR cigs should return later tonight...with VCSH
remaining common. Winds will remain generally 10 to 20 kts across
the area...and may increase slightly as Cindy makes her progress
to the northeast.
MIC
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 76 86 73 83 / 41 79 63 63
Meridian 75 86 73 84 / 48 69 62 64
Vicksburg 76 85 74 83 / 61 84 61 59
Hattiesburg 75 88 74 87 / 53 66 34 68
Natchez 76 85 73 82 / 59 77 63 61
Greenville 75 84 72 82 / 86 92 64 41
Greenwood 75 82 71 82 / 50 89 66 42
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flash Flood Watch through Friday evening for MSZ018-019-025>066-
072>074.
LA...Flash Flood Watch through Friday evening for LAZ007>009-015-016-
023>026.
AR...Flash Flood Watch through Friday evening for ARZ074-075.
&&
$$
NF/05/07/22
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1052 PM EDT Thu Jun 22 2017
.UPDATE...
Issued at 1052 PM EDT THU JUN 22 2017
Main area of rain with this first push has now moved northeast of
the CWA, with only isolated light showers lingering in the
southern CWA. Went ahead and reduced pops across the CWA through
much of the night to reflect this trend. Latest hi-res data also
supports this idea, however they also are all trending dry through
the morning across much of the CWA as well. This will be something
to continue to monitor over the next couple of hours, as further
updates to reduce pops may be needed closer to dawn. At this
time, have pops increasing towards scattered again by daybreak as
we get sun/heating taking place. Otherwise, grids seem to be in
good shape. Loaded in the latest observations to make sure
temps, dew points, and winds were on track with current
conditions. All changes have been saved and sent to NDFD/web. A
new forecast package was sent out to change to overnight wording
and reflect updated pops. An update to the Flash Flood watch was
also sent out, though no significant changes were made.
UPDATE Issued at 747 PM EDT THU JUN 22 2017
Continuing to monitor the rain as it moves across eastern
Kentucky, with what looks to be a pretty good back edge now moving
into our SW CWA. That being said, there is still another round of
precipitation located to our south that will likely make it into
our SE counties over the next few hours. Generally favoring the
HRRR solution which is initializing well with the ongoing
conditions, and has this secondary area of rain moving across the
eastern half of the CWA overnight. Will continue to monitor and
adjust pops and needed. Otherwise, main updates at this time were
just to make sure the temps, dew points, and winds were on track
with current conditions. All changes have been published and sent
to NDFD/web.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 504 PM EDT THU JUN 22 2017
The leading edge of deeper moisture associated with Cindy has
brought widespread showers to eastern Kentucky through the day.
Lightning has been scarce so far today, with most locations
receiving between a few hundredths of an inch and a half inch of
rainfall, as some downsloping flow has cut into totals.
The main band of showers will lift off to our northeast through
this evening, with generally lesser chances expected through the
overnight hours. A low level jet does pick up towards dawn, and
this may initiate some better areal coverage.
The remnants of Cindy will track up the Mississippi Valley on
Friday, before turning more northeast across the northern half of
Kentucky Friday night. An approaching cold front will interact
with this system, allowing for a period of heavy rainfall that
will move in to eastern Kentucky later Friday afternoon into
Friday night. The models have generally shifted the higher QPF
amounts more to the north with time, although given the high
moisture content of the air mass, any location would have the
potential for heavy rainfall and flash flooding.
As such, a flash flood watch is in effect from Friday afternoon
through early Saturday morning. Locations generally near and north
of a line from Mckee to Jackson to Inez will have the higher
flash flood threat, where the higher 6 hour QPF totals will
reside. Depending on the exact amounts, some significant river
rises will also be possible.
In addition to the heavy rainfall, there may also be a severe
threat window Friday afternoon into Friday evening, given the
stronger low level wind profiles in place and the proximity of the
low center. As is typical, instability will be in question as
mid-level lapse rates will be lacking. Have continued to
mention this potential in the HWO.
.LONG TERM...(Saturday through Thursday)
Issued at 244 PM EDT THU JUN 22 2017
The extended portion of the forecast begins on Saturday with the
upper level pattern featuring a stout ridge over the western CONUS
transitioning into a trough over the Great Lakes. The first wave
associated with the combination of tropical moisture and a cold
front will finally exit the area at the start of the forecast
period. So will see a chance of showers over eastern Kentucky
through the day on Saturday as the last of the showers exit the
area by the evening. This will usher in a dry period as models
have trended drier and drier. The mentioned stout ridge in the
west will build as it shifts east nudging the axis over the
Midwest by Wednesday. In addition, a bubble of surface high
pressure will carve out an area of subsidence over eastern
Kentucky and much of the central Appalachians. In fact, the
airmass intrusion behind Cindy will bring some welcomed cooler
temps to start next week with highs in the 70s expected through
Wednesday.
One difference in the forecast might be on Monday afternoon as the
most recent 12Z Euro and GFS has brought a weak wave dropping far
enough south to bring a small chance of showers and a
thunderstorm. This is a change to the model trends so am more
inclined to keep the dry forecast inherited from the super blend.
Otherwise, the extended features dry weather and slightly cooler
high temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 756 PM EDT THU JUN 22 2017
Showers continue to impact much of eastern Kentucky this evening
as a result of moisture advection associated with Tropical Storm
Cindy. There is a defined back edge to this round of showers,
with drying now occurring at the southern most TAF sites.
However, another round of showers is set to begin moving in over
the next hour or two. CIGS are varying across much of eastern
Kentucky, though predominately VFR, with VIS generally P6SM
except where the heaviest rain showers are currently occurring
(KSYM and KJKL). Expect the VIS to improve as these heaviest bands
move out. As for the rest of the night and into the day tomorrow,
there is still quite a bit of uncertainty. Latest trends in the
Hi-Res models are showing a bit of clearing late tonight and
through the morning at most of the TAF sites before round 2 (the
heaviest rainfall) moves into the region from the west ahead of an
approaching frontal boundary. If this dry period pans out we
could see some transitions between MVFR and VFR conditions through
tomorrow morning, but also cannot rule out some potential fog
development. Low level wind shear will threaten later tonight as
well, as 850 mb winds remain around 40 to 50 kts, while south to
southeast winds at the surface remain at around 5 kts or less. By
tomorrow afternoon expect winds to begin picking up from the SW at
the surface, and showers and thunderstorms moving back into the
region, with a general trend towards MVFR CIGS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from Friday afternoon through Saturday morning
for KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...JMW
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...JMW
Area Forecast Discussion
National Weather Service Louisville KY
1154 PM EDT Thu Jun 22 2017
.Forecast Update...
Issued at 1150 PM EDT Thu Jun 22 2017
Issued an update for current radar trends. Looks like we can cut
down on pops some for the rest of the night period, and latest hi-
res guidance does not call for the banded precip over southern IN
until a little later this morning. Also, the development may end up
over our northern row of counties, if not just north of them in
IND`s area. Latest NAM has backed off quite a bit on the low-level
jet ramping up overnight, so consequently, it does not have nearly
as strong of a rains as in its previous runs. Latest RAP is mor in
line with current winds on the LVX VWP, and it still brings in a
stronger jet the rest of the night, with the best convergence again
along that northern row of counties in southern IN.
We still look to have a solid slug of rains moving across the entire
region Friday...so no need to change any of the current Flash Flood
Watch.
Issued at 637 PM EDT Thu Jun 22 2017
The widespread area of light to moderate rainfall has lifted to the
north of the Cumberland Parkway early this evening. To the south of
this area, scattered showers continue to move north out of TN. There
looks to be a relative lull in precipitation later this evening as
the larger rain shield lifts out. Thereafter, rain chances will be
on the increase again, particularly across southern IN during the
early morning hours as discussed in the short term discussion below.
Some changes were made to the pops for this evening to better
reflect the expected lull, though at least slight chances were left
in everywhere through the night.
&&
.Short Term...(This evening through Friday night)
Issued at 223 PM EDT Thu Jun 22 2017
...Torrential Downpours Expected...
...Minor Flooding of Small Rivers and Streams Possible...
...Isolated Tornado Not Out of the Question...
~~Main Threats and Timing~~
The best chance for heavy rain in southern Indiana will be from
after midnight tonight through Friday. The best chance for heavy
rain in central Kentucky will be Friday afternoon and evening.
The best chance for isolated tornadoes or damaging wind gusts will
be Friday afternoon in central Kentucky, especially the Lake
Cumberland region. There is also a small chance of an isolated brief
spin-up or wind gust over southern Kentucky this evening.
~~Summary~~
A cold front coming in from the northwest will meet up with the
remnants of Tropical Storm Cindy coming up from the southwest,
leading to widespread rain. Plentiful atmospheric moisture will
result in locally torrential downpours.
~~Rainfall Amounts~~
General amounts of 1 to 3 inches are expected, with embedded bands
of heavier rain. Today`s model runs, with some exceptions, have come
into decent agreement showing the band of heaviest rain between I-64
and the Cumberland Parkway.
~~Confidence~~
At this time, confidence is high that a band of heavy rain will set
up, likely over central Kentucky. Confidence of heavy rain is less
in southern Indiana and southeastern sections of central Kentucky
(Lake Cumberland area).
Small changes in the track and timing of Cindy will lead to
significant changes in where the heavy rain sets up.
~~Details~~
Tropical Depression Cindy, centered near Shreveport, Louisiana at
the start of the short term, will head north into Arkansas tonight
and then northeast into southern Kentucky Friday afternoon.
Meanwhile, a cold front will approach from the northwest, reaching
the Ohio River by Friday evening. It will then pick up Cindy`s
remnants and whisk them off to northern Virginia by dawn Saturday.
The models, including the HWRF, have come into pretty good agreement
with this.
The rain this afternoon has been efficient, with moderate to
briefly heavy rain despite radar dbz`s only in the 40s. As of 1pm
CDT the Kentucky Mesonet site in Simpson County already received
nearly an inch and a half of rain. The rain will continue to move to
the northeast late this afternoon and evening. The HRRR has been
very consistent with the idea of sprouting isolated convection
behind the departing steady rain early this evening. The chance of
isolated showers/storms will be enhanced during a brief window
before sunset if the breaks in the overcast currently over the lower
Mississippi Valley can work their way in. Isolated wind gusts or
even a brief, weak spin-up wouldn`t be out of the question given
strong low level shear and stronger winds aloft as seen on OHX VWP.
After midnight rain chances will increase significantly over
southern Indiana as moisture pools ahead of a cold front approaching
from the northwest and low level jetting increases. Precipitable
water values will increase to 2 to 2.5 inches, leading to locally
heavy downpours.
On Friday the front and Cindy`s circulation will feed on deep
moisture to produce widespread showers and scattered thunderstorms
with torrential downpours. Low and mid level winds will increase
Friday afternoon and low level shear will be strong ahead of and to
the right of the circulation. Though insolation will be at a premium
and instability will be weak, rotation will be possible in the low-
topped convection and could result in isolated wind gusts or brief,
weak tornadoes in central Kentucky. If we get some breaks in the
cloudcover to increase instability, severe chances will increase.
The best chances will be in the Lake Cumberland region.
.Long Term...(Saturday through Thursday)
Issued at 229 PM EDT Thu Jun 22 2017
The long term will be quiet as Canadian high pressure slowly makes
its way across the central and eastern United States. Could see some
valley fog in the Lake Cumberland region Saturday morning.
Temperatures will be very mild for early summer, with highs in the
70s to around 80 through Wednesday, then warming up a bit late in
the week.
&&
.Aviation...(00Z TAF Issuance)
Issued at 717 PM EDT Thu Jun 22 2017
A large area of light to moderate rain will continue to lift north
this evening. This rain may drop visibility at SDF and LEX to 2SM or
less at times over the next couple of hours. Thereafter, there
should be a lull in precipitation at all the TAF sites. There may be
some brief improvement in the ceilings to VFR during this time as
well.
However, as the remnants of Cindy approach early tomorrow morning,
ceilings will lower to MVFR once again. Rain chances will be on the
increase from the morning into the afternoon with a few
thunderstorms possible. Rain will be heavy at times which could
lower visibilities to IFR or below temporarily in the heaviest
showers, mainly tomorrow afternoon. Winds will be gusty out of the
south-southwest through the day Friday.
&&
.Hydrology...
Issued at 259 PM EDT Thu Jun 22 2017
Areas of heavy rain will extend northward tonight. The rain will end
after midnight early Saturday morning. This is due to a combination
of the remnants of Tropical Storm Cindy coming up from the south and
a cold front sweeping in from the northwest. Between 1 and 3 inches
of rain are expected with the entire system. It is important to
note, though, that within this general area of rain there may be
narrow bands of higher amounts where thunderstorms train over the
same locations.
This will lead to rises streams in the area with minor flooding
possible. The largest threat will be in the Green, Barren, and Rough
basins. However, only minor flood levels are expected.
In addition, thunderstorms will produce locally torrential downpours
which could lead to flash flooding.
If you live in a flood prone area, watch water levels closely over
the next few days.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Flash Flood Watch through late Friday night for INZ076>079-083-
084-089>092.
KY...Flash Flood Watch from 11 AM EDT /10 AM CDT/ Friday through
Saturday morning for KYZ023>043-045>049-053>057-061>067-
070>078-081-082.
&&
$$
Update...RJS/EER
Short Term...13
Long Term...13
Aviation...EER
Hydrology...CMC
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
915 PM CDT Thu Jun 22 2017
.UPDATE...
915 PM CDT
Main concern is isolated risk for strong to severe thunderstorms
tonight. Forecast is largely in good shape, with no significant
changes needed to the grids. The surface cold front is fairly
diffuse across Wisconsin this evening. Some scattered shower
activity with thus far no lightning observed has broken out north
of I-88 in Illinois. While the strongest mid and upper level and
jet forcing lags to the north the more widespread thunderstorm
activity from central IA to central and southern WI is tied to the
cold front and a subtle shortwave noted on W/V imagery.
The shortwave and front will gradually drag this higher coverage
of thunderstorms southward tonight. Current thermodynamic
environment features moderate instability and fairly weak deep
layer wind shear. As the higher coverage of thunderstorms arrive
tonight and sag south through the night, SBCIN and MLCIN should
gradually wane despite warm and humid air mass ahead of the front
with nocturnal stabilization, while MUCAPE will remain in
1500-2000 j/kg range. A modest increase in winds aloft
accompanying the shortwave will bump up deep layer shear a bit,
though still fairly marginal. The moderate instability and
marginal to moderate shear environment will be supportive of
isolated stronger thunderstorms. Had coordinated with SPC to lower
severe risk to Marginal/Isolated. Main risks from any
strong/severe storms will be wind and hail. In addition, high PWAT
air mass (near 2") will make the more intense storms very
efficient rain producers, so some ponding/localized flooding can`t
be ruled out.
Castro
&&
.SHORT TERM...
225 PM CDT
Through Friday...
Concerns center around isolated thunderstorm development this
afternoon, and then with a line of storms late this evening and
overnight.
Inhibition gradually continues to erode from the south generally
driven by low level moisture advection soundings. AMDAR soundings
still depict some decent capping thanks to fairly warm
temperatures in the 800-700 mb layer, at least closer to Chicago
The HRRR now has backed off a bit on the coverage for the
afternoon and early evening, consistent with very little/weak
convergence in place and a lack of a larger scale forcing
mechanism. But there is some weak upper forcing pushing in from
the south, thus we maintain an isolated shower and storm mention
for the afternoon/early evening. Shear profiles are still fairly
weak during this period thus severe threat is low.
We will hang onto instability through the evening ahead of the
cold front currently draped across the northern plains/upper
midwest. Stronger upper level winds will approach the area along
the southern fringes of the upper low across Manitoba. Clusters of
storms will continue to develop along and ahead of the front. Any
storms that area able to get going this evening ahead of the front
will form in an axis of 1000+ J/Kg of MLCAPE and shear in excess
of 30 kt, which keep the threat of hail or locally damaging winds,
mainly across north central IL this evening, especially if
anything forms upstream and develops a cold pool while pushing
ahead into the continued unstable airmass. The cold front will
pass through the Chicago area after midnight, with the line of
storms passing southeast with it. There are some waves in the
southwest flow aloft that may initially slow the progression of
the front before it gets shoved southeastward late tonight, and
may prevent a solid line, but confidence is pretty high in many
areas seeing some activity. Moisture pooling ahead of the front
would suggest at least some brief heavy downpours in this
scenario, while the more significant flood threat is largely just
to our north/northwest.
Quite the airmass change will filter air on Friday, with much
drier air across the upper Midwest (note the 40s Tds in MN). These
will not get here that quickly but eventually will get in here
this weekend. Still humidity levels will be much lower, and temps
look to top off in the upper 70s to near 80. It may be a bit
cooler along the IN shore. Showers and storms look to still be
ongoing tomorrow morning, but guidance is in good agreement of
getting the front through in the afternoon.
&&
.LONG TERM...
238 PM CDT
Friday night through Thursday...
For the longer term forecast period, general trends remain
consistent with previous runs and the short term forecast period
trends.
By Friday night, the longwave pattern will be trending toward a
higher amplitude with building ridging over the west coast and broad
troughing over the ern 2/3 of the CONUS. The broad upper trough
will help contribute to a period of below normal temperatures for
the weekend through early next week. The local area will be under
fast nwly flow aloft, with a series of nrn stream shortwaves
dropping through the nwly flow, sharpening the upper trough and
generating sct showers. Chances for thunderstorms will be low,
though not out of the question for the afternoon hours. The highest
chance for any pcpn through the weekend will likely be Sunday
afternoon into Sunday evening when a stronger shortwave is expected
to drop through the upper Mississippi Valley and across the upper
Great Lakes. There are some strength differences noted in the
longer range guidance, with the ECMWF trending stronger than the
GFS/GEM, though all indicate similar timing. So, will carry chance
PoPs for the nrn portions of the CWA with some scattered
thunderstorms possible. Any pcpn should be scattered, so the day
should not be a washout. Temperatures for the weekend through early
next week will be below normal, with highs only in the lower 70s
through Monday. With high pressure associated with a dry continental
polar air mass sliding out of Canada and across the cntrl Plains and
Mississippi Valley, dewpoints will also be anomalously low for late
June and should only be in the upper 40s to around 50 F.
By Tuesday, the upper ridge is still expected to build east across
the Rockies and out over the cntrl CONUS while sfc high pressure
shifts to the east coast. Rising heights aloft and increasingly sly
flow at the sfc will set up a return flow of warm/moist air with
temps reaching the upper 70s for Tuesday and the lower 80s for
midweek. Dewpoints should also be on the rise back into the upper
50s to lower 60s.
&&
.AVIATION...
For the 00Z TAFs...
The scattered shower and isolated thunderstorm development across
the area has seen somewhat of a diminishing trend, with latest
radar imagery depicting lower coverage of both. Don`t anticipate
any increasing trend of coverage through mid evening, with MDW and
GYY having the highest chances of observing a brief shower in the
near term. VFR conditions in place at this time and it does appear
that MVFR ceilings will try to move overhead this evening, but
likely not arriving until later tonight. This will occur with
increasing chances for showers and thunderstorms, stemming from
currently development across WI and eastern IA. No real big
change with this thinking, with this development not arriving
until late tonight into early Friday morning. Will continue to
monitor trends this evening, as coverage and timing of these
thunderstorms could possibly change. Southwest winds will persist
for much of tonight until FROPA turns winds to the north
northwest. Have continued a north northwest wind through Friday,
but in this setup, lake breeze development is a possibility. If
this were to occur, a wind shift to the east in the afternoon
would be possible. However, low confidence with this possibility
at this time, and have continued the northwest direction.
Rodriguez
&&
.MARINE...
245 PM CDT
The low over western Manitoba will weaken as it crosses Ontario
tonight and then continues to Quebec Friday. An associated cold
front will sweep across the lake tonight into early Friday
morning with winds becoming west to northwest behind the front.
Westerly winds are expected to continue through early next week.
High pressure should then build in behind the exiting cold front,
spreading across the plains Sunday and the western Great Lakes
early next week, setting up a period of relatively light and
variable winds. As the high shifts to the east and new low
pressure develops over the northern plains, winds will trend more
southerly and strengthen to arnd 15 to 20 kt by Tuesday. A
strengthening southerly pressure gradient could bring winds up to
30 kt by mid week as high pressure remains parked over the sern
CONUS and the trough and associated cold front track east across
the plains.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
744 PM EDT Thu Jun 22 2017
.SHORT TERM...(This evening through Friday)
Issued at 406 PM EDT THU JUN 22 2017
Water vapor imagery and RAP analysis show a deep mid-level low over
southern Manitoba (500mb height anomalies around 230m). Low is
embedded in overall broad, low-amplitude troffing centered over
central N America. In the weakly cyclonic flow across the n central
CONUS, shra/tstms have been tracking from the eastern Dakotas/IA
toward Lower MI today, aided by right entrance of 120kt upper jet
extending from northern MN across northern Ontario and low to mid
level frontogenesis. Northern edge of this pcpn extends about as far
n and w as a Watersmeet to Marquette line.
As upper jet axis and frontogenesis drift se tonight, ongoing shra
and isolated embedded thunder will also shift se. Much, if not all,
of the shra should be se of the fcst area by 06z. Otherwise, over
the next 24hrs, the deep mid-level low over southern Manitoba will
open up as it moves ese, with remnant vort max passing across
northern Lake Superior Fri aftn. Ahead of it, another shortwave trof
currently over MT/ND will also shift e, moving across Upper MI late
tonight/Fri morning. Not really anything going on ahead of the
latter wave. Farther w and nw under colder mid-levels, isold shra
are developing in nw ND. Given arrival of wave late tonight/Fri
morning, these shra will likely have dissipated before reaching the
area.
On Fri, remnant of the Manitoba mid-level low will arrive at a more
favorably aligned time with respect to daytime heating. Lingering
low-level moisture over the eastern fcst area combined with Lake
Superior lake breeze aided windshift may support sct -shra over the
eastern fcst area inland from Lake Superior in the aftn. No mention
of thunder was included in fcst. However, with model consensus for
mlcape of a couple hundred j/kg, not out of the question that there
could be a rumble or two of thunder. To the w, cooling mid-levels
under somewhat sharper troffing might support a few sprinkles or an
isolated -shra inland. At this point, lack of instability suggests a
mention of pcpn in fcst is not warranted. Otherwise, looks like a
breezy day under deep mixing. Expect gusts to 20-30mph over the w
and central, strongest over the Keweenaw. Deep mixing should also
support dwpts falling to or blo lowest guidance, but no fire wx
issues given the surplus of rainfall over the last couple of weeks.
.LONG TERM...(Friday night through Thursday)
Issued at 409 PM EDT THU JUN 22 2017
The wet and cooler than normal trend will continue through much of
the extended portion of the forecast.
The general trend for much of the extended forecast continues to be
the troughing over the east half of the CONUS with ridging expected
to linger over the west half. The main impact that this will have on
the weather in the U.P. will be increased cloud cover along with
intermittent chance for rain showers and isolated afternoon
thunderstorms. The better chances for rain will occur with the
diurnal instability cycle, during peak heating in the afternoon and
synchronized with the multiple shortwaves sliding around the trough
the area. At this point, the more widespread focus will likely be
Saturday through Sunday, mainly in the afternoon, as a stronger
upper-level disturbance slides through or just south of the U.P.
Temperatures will generally be in the mid to upper 60s with
overnight lows in the 40s to around 50.
Toward the end of the extended forecast, Tuesday through Thursday,
models are trending toward a bit of a brief break in the troughing
across the area. This will allow a brief ridge to build in ahead of
a cold front that is expected to slide into the area Wednesday into
Thursday. As the front slides through Wednesday afternoon into
Thursday, the chance of showers and thunderstorms will return once
again. Ahead of this front and under the ridge, temperatures will
warm closer to normal with highs in the mid to upper 70s and lows in
the mid to upper 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 741 PM EDT THU JUN 22 2017
VFR conditions are expected to prevail at KIWD/KCMX/KSAW through the
forecast period with sct-bkn diurnal cu developing by Friday
afternoon. Gusty winds will develop Friday morning, especially at
KCMX which is more exposed to westerly winds. Gusts up to 30kt are
expected late morning thru the aftn.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 406 PM EDT THU JUN 22 2017
Vis satellite imagery has given hints of patchy fog on Lake Superior
today. This patchy fog may linger tonight and then perhaps thru Fri
over far eastern Lake Superior. Winds will remain generally below
20kts into early next week. Stongest winds should occur later
tonight thru Fri evening when gusts may reach 20-25kt at times.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...KEC
AVIATION...JLB
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Omaha/Valley NE
618 PM CDT Thu Jun 22 2017
.UPDATE...
Issued at 615 PM CDT Thu Jun 22 2017
So far, the cap has been holding. The synoptic scale cold front
is still northwest of Omaha and Lincoln, so still potential yet
this evening. Even after the front passes, there may be some
activity behind the boundary. 22Z SPC mesoanalysis suggests cap
is weakest to the north and northeast of Omaha, with lowest
100 mb MLCAPE around 2000 J/kg and CINH less than 25. RAP model
may be a bit overdone with precipitation coverage and amounts,
based on what happened last evening. 21Z ESRL HRRR suggest some
activity developing by 01Z and then even into tonight.
&&
.SHORT TERM...(Tonight through Sunday)
Issued at 302 PM CDT Thu Jun 22 2017
12z upper-air analysis revealed a belt of stronger cyclonic flow
from the northern Rockies into the Dakotas with an embedded short-
wave trough over the northern High Plains. This disturbance will
track southeast into the mid MO Valley tonight into early Friday,
enhancing forcing for ascent and vertical shear ahead of it. In
the low levels, mesoanalysis depicted a cold front stretching from
north-central IA through northeast into south-central NE as of
early afternoon. The boundary layer ahead of this front has been
warming and moistening today, which when coupled with the steep
lapse rates aloft is yielding a moderately unstable air mass this
afternoon.
Considerable elevated convection is ongoing across the area as of
19z, likely rooted within the EML/steep lapse-rate plume. And
latest convection-allowing model guidance remains relatively
consistent in suggesting that surface-based storms will become
increasingly probable in the 22-00z time frame, generally along
the I-80 corridor. A few of these storms could become strong to
severe this evening with locally damaging winds and hail being
the primary hazards.
Showers and thunderstorm chances should diminish from north to
south tonight into early Friday as a cooler, continental-polar
air mass advances south into the region. This air mass will remain
in place over the mid MO Valley through the weekend with daytime
highs in the 70s.
.LONG TERM...(Sunday night through Thursday)
Issued at 302 PM CDT Thu Jun 22 2017
Longwave troughing from Hudson Bay into the OH Valley at the onset
of the long-term forecast period will gradually shift east ahead
of an evolving trough over western Canada into the northwestern
states. The latter trough will subsequently progress east into the
north-central Plains, supporting an increase in precipitation
chances by about the middle of next week. Daytime highs will
gradually warm back through the 80s during the early to middle
part of the upcoming work week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 615 PM CDT Thu Jun 22 2017
Wind shift will move through the KOMA and KLNK areas early this
evening. Generally expect VFR conditions through the period.
Ceilings with any TSRA could drop below 2500 feet and vsby could
drop below 3 miles, but confidence on exactly when and where is
not high enough to include in TAFs. Will amend as needed. Expect
variable mid clouds after 06z. North winds may be a bit gusty
right behind the cold front for a while, then decrease.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
UPDATE...Miller
SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Miller
Area Forecast Discussion
National Weather Service Mount Holly NJ
908 PM EDT Thu Jun 22 2017
.SYNOPSIS...
Low pressure will track well north of our area Friday and Saturday.
An associated cold front crosses our region during Saturday as some
tropical moisture moves ahead of and along it. As high pressure
builds well to our southwest Sunday into Monday, a weak cold front
moves through our area later Monday. High pressure then builds
across the Mid Atlantic Tuesday and Wednesday, before shifting
offshore Thursday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
While the showers and thunderstorms have weakened and
consolidated across central PA, they continue to track to the
east. POPs were raised to likely adjacent to the CTP CWA. Chance
POPs and the threat of showers were also painted further east
into the western Philly suburbs as the HRRR continues to show
showers approaching I95.
Previous discussion...
The 6:30 pm ESTF update will include a few tweaks with temps
and dewpoints. Sky, weather, and POPs were also adjusted across
our far western zones as the showers and thunderstorms are
dissipating a bit more slowly. The HRRR brings some precip to
I95 corridor between 03-04z, but we feel this over done.
Previous discussion...
The first challenge of the near term forecast will be if and
how quickly any convection associated with a low level trough to
our west reaches our region by early this evening. Showers and
thunderstorms have already developed across western PA, but it
is unclear if they will reach our region before sunset, when we
should see activity diminish (this convection appears to be very
much diurnally driven as there is limited forcing in the mid
and upper levels and model soundings show a low level inversion
developing quickly this evening.
Through the overnight hours, the closed low over south central
Canada is expected to continue gradual progress east. As it does so,
we may begin to see the next round of showers and thunderstorms move
into our region in the pre dawn hours, though latest model timing
indicates it is unlikely we will see this before daybreak.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As the low and it`s associated cold front make slow progress east,
it will interact with remnant moisture of TD Cindy. Through much of
the day tomorrow, it looks like the axis of the deepest moisture and
best lift generally stay to our north and west. Having said that
though, it is likely that some convection will move into our region
through the day especially west of the fall line. It is also likely
that we will keep mid level clouds over our region for much of the
day as the mid level cloud shield associated with this is already
moving into SW VA. Cloud cover will be crucial in determining our
severe potential tomorrow afternoon. Model soundings indicate that
if we can see some clearing by mid day, we could have CAPE values in
our region over 500 J/kg. Bulk shear remains limited (generally less
than 30 kt) until very late in the day. Thus, any severe threat
(hail and strong winds) will be conditional on clearing early enough
in the afternoon.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Summary...Tropical moisture moves through Friday night and the first
half of Saturday with a cold front, then lowering humidity levels
during the second part of the weekend and next week. Some cooling
next week as a trough settles into the East for a time.
Synoptic Overview...An upper-level trough amplifies eastward from
the Midwest and Great Lakes to the Northeast through Sunday. This
will send a cold front our way, however the remnants of tropical
system Cindy interacts with it. This feature, while possibly less
defined at the surface, should have its mid level energy enhance our
chances for locally heavy rain later Friday night and Saturday
morning. The trough is then forecast to sharpen in the East through
the first half of next week, before lifting out later Wednesday or
Thursday. The presence of this trough will result in cooler
temperatures for a few days, with perhaps some instability
showers/thunder especially early in the week. We used a
model/continuity blend for Friday night through Saturday night, then
blended in the 12z WPC Guidance. Some adjustments were then made
following additional collaboration with our neighboring offices.
For Friday night and Saturday...As a trough amplifies eastward from
the Midwest and Great Lakes region, surface low pressure tracks well
to our north. An associated cold front however will be moving
through our area Saturday. While this occurs, the remnant energy
from tropical system Cindy gets caught up in the faster flow aloft
as it moves northward and then accelerates east-northeastward. While
the surface feature should be less defined, the model guidance shows
the mid level energy holding together as it crosses especially the
southern half of our area Saturday morning. There is an axis of very
high moisture content air moving east with PW values of 2.0-2.5
inches. This moisture in combination with lift from the front and
remnant tropical system Cindy will result in locally heavy rain.
While there is some potential for localized flooding, the system
should be moving through fairly quickly. As a result, we held off on
a Flash Flood Watch at this time. This may have to be revisited
though especially for the urban I-95 corridor. The main area of
concern looks to be from the Philadelphia metro area on south and
eastward. The forecast soundings generally show a tall and thin CAPE
profile, which within a very moist air mass tends to lead to areas
of locally very heavy rain. Backing up a bit, there should be
ongoing convection to our west that spreads eastward Friday night
with the front and then the tropical system remnants. We have an
area of likely PoPs across the western/northern areas Friday
evening, then these spread south and eastward overnight and increase
to low end categorical toward daybreak for some areas. For Saturday,
we confined an axis of likely to low-end categorical PoPs to mostly
the morning hours. At least some clearing should then occur from
west to east Saturday afternoon and especially at night with dew
points dropping in the wake of the cold front. It is possible that a
few showers or thunder develops in the afternoon especially across
the eastern and southern zones where lingering instability is
present before the front clears the coast.
For Sunday and Monday...An upper-level trough is forecast to amplify
across the East during this time frame. This should be accompanied
by a secondary cold front at the surface later Monday. While Sunday
overall looks dry with lowering dew points, some instability showers
or low-topped thunderstorms will be possible Monday especially in
the afternoon to early evening. The presence of the upper-level
trough and accompanying cooling aloft will result in cooler surface
temperatures especially more noticeable on Monday.
For Tuesday through Thursday...The upper-level trough in place
Tuesday into Wednesday may begin to lift out later Wednesday or
Thursday. This will allow surface high pressure to build in from the
west-southwest before shifting offshore Thursday. As the main part
of the trough is overhead Tuesday, there will be the chance for some
instability showers during the daytime. The dew points are
anticipated to be in the comfortable zone due to the presence of the
trough and associated cooler air mass. Some moderating of the
temperatures is expected Wednesday and especially Thursday as high
pressure moves offshore and a warm air advection pattern should
begin.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
With showers and isolated thunderstorms still holding together
and now working through Berks and Lancaster counties, VCSHs were
added to the I95 terminals.
Previous discussion...
Tempo -SHRA was added to both KRDG and KABE between 23z and 02z
to account for the showers and thunderstorms moving in from the
west.
Previous discussion...
VFR conditions are expected to continue through at least 00Z, and
likely through 06Z. After 00Z lower clouds and showers and
thunderstorms are expected to approach the region from the
southwest. Though the chance for showers and thunderstorms begins
after 00Z, it looks more likely that precipitation will hold off in
our region until closer to 12Z. With any showers and thunderstorms,
MVFR conditions are likely, and IFR conditions are possible,
especially with heavy downpours which are possible tomorrow morning.
Conditions may improve to VFR for several hours after 18Z.
OUTLOOK...
Friday night and Saturday...Times of MVFR/IFR conditions with
showers and some thunderstorms. Some heavier rain can significantly
reduce the local visibility at times. The greatest coverage of
showers should be late Friday night and Saturday morning, with
improving conditions Saturday afternoon and night.
Sunday...VFR overall.
Monday and Tuesday...VFR overall, however a few mainly afternoon and
early evening showers or a thunderstorm are possible each day.
&&
.MARINE...
Winds and seas should stay below SCA criteria through Friday
morning. By mid day seas and southwesterly winds will increase on
the coastal waters and SCA conditions are likely to develop by early
afternoon. Strong winds are possible in the vicinity of any
thunderstorms that may develop especially Friday afternoon.
OUTLOOK...
Friday night and Saturday...A cold front will approach Friday night
with some increase in a southwesterly flow. The forecast soundings
indicate that the mixing is not all that efficient due to a very
warm and humid air mass, however times of 25-knot gusts can occur
and this should build the seas on the ocean to around 5 feet. As a
result, a Small Craft Advisory was issued for only the ocean zones
through 10z/6 AM Saturday. This advisory may need to be extended
through much of Saturday prior to the frontal passage.
Sunday through Tuesday...The conditions are anticipated to be below
Small Craft Advisory criteria during this time frame, with subsiding
seas during Sunday.
RIP CURRENTS...
We are forecasting that the low risk for the formation of dangerous
rip currents will continue into tomorrow. However, even with a low
risk...the bigger diurnal difference in the tide cycle as we
approach the date of this months new moon could mean some rapidly
changing conditions.
&&
.TIDES/COASTAL FLOODING...
High astronomical tide levels are expected in association with the
new moon on Friday. That, combined with increasing southerly flow,
is expected to result in minor coastal flooding with the afternoon
and evening high tide for the Atlantic coastal areas and the shores
of the lower Delaware Bay. There may be minor coastal flooding
further up the bay, but it is unlikely, so will not expand the
coastal flood advisory at this time.
Minor coastal flooding may occur again with the high tide cycle
Friday afternoon and evening, though the latest guidance has backed
off slightly from previous runs. We will have a better idea of the
potential tomorrow once we see the tidal departures this evening.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Advisory until 9 PM EDT this evening for
NJZ012>014-020-022>027.
DE...Coastal Flood Advisory until 9 PM EDT this evening for DEZ003-
004.
MD...None.
MARINE...Small Craft Advisory from noon Friday to 6 AM EDT Saturday for
ANZ450>455.
&&
$$
Synopsis...Gorse
Near Term...Johnson
Short Term...Johnson
Long Term...Gorse
Aviation...Gorse/Johnson
Marine...Gorse/Johnson
Tides/Coastal Flooding...
Area Forecast Discussion
National Weather Service Shreveport LA
1020 PM CDT Thu Jun 22 2017
.DISCUSSION...
The center of TD Cindy continues to weaken as it shifts NE into
extreme Srn AR this evening, with sfc obs depicting the center
between TXK and ELD as of 03Z. Much of the convection containing
heavy rainfall remains localized near and just S of the center,
from near SHV E to RSN, with the continued dry air entrainment
having limited convection development across much of Ncntrl LA.
However, believe this will change overnight as Cindy continues to
open up into an elongated upper trough as she continues to lift NE
into Scntrl AR, with the trailing H850 trough expected to linger
across Scntrl AR into extreme Nrn LA near the I-20 corridor. S of
this bndry, a 40-50kt Swrly LLJ will continue S of the ejecting
low center, resulting in a period of continued convergence along
the H850 trough and thus renewed development. In addition, 0-6km
winds are expected to remain unidirectional overnight, with the
potential for training across much of Ncntrl LA as evident from
the ongoing convection over extreme SE TX/SW LA over the last
couple of hours. PW`s remain near or in excess of 2.5 inches, with
the strong low level shear expected to maintain/aid in additional
redevelopment overnight. Despite little rainfall having already
fallen over this area, the HRRR and 00Z NAM suggest that
additional rainfall amounts of 1-3+ inches are possible, with
isolated higher amounts of 5+ inches, which could result in
localized flash flooding.
Given this, have cancelled the Flash Flood Watch for all of E TX
as well as Lafayette and Columbia Counties in SW AR W of the
center, but will allow the existing watch to continue for Union
County AR and all of N LA. Should the HRRR/NAM indeed verify, it`s
possible the watch may need to be extended for much of Friday
morning for portions of Ncntrl LA until the heavy rain threat
diminishes by midday. Winds have been struggling across much of
the earlier Lake Wind Advisory, thus have cancelled the Advisory
early. Have also adjusted pops, mainly to drop pops for SE OK and lower
them across E TX/portions of SW AR. Did maintain
likely/categorical pops for N LA/Scntrl AR with the expectation of
renewed development overnight. Did have to make some changes to
pops Friday as well, as the highest pops will remain concentrated
during the morning over N LA. Did lower them elsewhere to low/mid
chance, with diurnal heating contributing to increased instability
ahead of a weak sfc front that will approach SE OK/SW AR Friday
afternoon, resulting in the potential for sct convection. Did make
some minor tweaks to min temps tonight, as only little change is
expected.
Zone update/FFA/NPW cancellation already out...grids will be
available shortly.
15
&&
.PREV DISCUSSION... /issued 717 PM CDT Thu Jun 22 2017/
AVIATION...
For the ArkLaTex, range of flight categories from VFR TX to IFR
LA/AR as TD Cindy moves pretty much overhead. Sfc winds are all
over the place with Southwest to prevail in the wake of the
system. Still gusty S in LA, ENE AR and SW in TX. Aloft, our climb
winds are NW and back to SW for flight levels abv FL200 with only
20-40KTS in the profile. The low will eject NE overnight and the
rain with, but IFR/MVFr cigs and vsby remain. An approaching cold
front will arrive tomorrow late into Sat a.m. with TSTMS. /24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 76 88 74 83 / 80 50 60 60
MLU 76 86 74 83 / 90 80 60 70
DEQ 73 89 70 84 / 20 40 60 40
TXK 74 87 72 82 / 50 40 60 60
ELD 75 85 72 82 / 90 80 60 60
TYR 76 91 74 84 / 20 20 60 60
GGG 76 89 74 83 / 40 20 60 70
LFK 76 90 76 86 / 50 20 40 70
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Flash Flood Watch until 7 AM CDT Friday for ARZ073.
LA...Flash Flood Watch until 7 AM CDT Friday for LAZ001>006-010>014-
017>022.
OK...None.
TX...None.
&&
$$
15