Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/24/16
Area Forecast Discussion
National Weather Service Bismarck ND
1040 PM CDT Fri Sep 23 2016
.UPDATE...
Issued at 1040 PM CDT Fri Sep 23 2016
Convection continues to increase/lift north/northeastward into
and across southwest and central North Dakota, along a low level
convergence zone as forcing aloft increases as divergent flow
overspreads the Northern Plains. Modified POPs based on latest
model data and radar trends. HRRR is catching up and I was able
to actually use its reflectivity output somewhat for this update.
Will need to keep a close eye on precipitation totals as the area
of convection over the southwest continues north into northwest
and north central areas. These areas received the higher rainfall
totals the past 12-24 hours and additional moisture may create
some problems depending if the robust convection can sustain
itself.
UPDATE
Issued at 833 PM CDT Fri Sep 23 2016
As forcing begins to increase from south to north, showers and
storms are now flaring up across portions of the southwest and
south central. Quick update sent to speed up the increase in POPs
and to try to fine tune the aerial coverage.
While we remain in the Marginal Risk area (southwest), SPC has
removed the Slight Risk area from North Dakota. Agree with this
change.
UPDATE
Issued at 615 PM CDT Fri Sep 23 2016
We are mainly dry across western and south central ND at the
moment so significantly reduced POPs for these areas. Main band of
showers and scattered thunderstorms currently lifting north-
northeast across north central and eastern ND. Kept high POPs for
these areas. Models are trying to catch up to radar, so populating
POP grids was a bit tricky for this update. High res models
continue to be in agreement with convection developing over or
into southwestern ND this evening and lifting north and northeast
across the area. Additional development possible elsewhere as the
surface low lifts north and embedded mid level energy approaches
the state this evening. Will likely have to send 2-3 updates over
the next 3-5 hours to account for radar trends. Last couple of
HRRR iterations have backed off on robust convection across the
southwest, so will see if this trend continues. Will continue to
mention possible severe storms in the State Forecast and HWO
products for the southwest.
Other update was to trend sky cover down over my south central and
southeast a bit more. Latest visible satellite imagery shows
clearing moving towards my far southeast counties now with both
the HRRR/RAP/NAM showing this trend continuing north and slightly
northwestward as we progress through the evening and into later
tonight.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 248 PM CDT Fri Sep 23 2016
Severe thunderstorm potential southwest this evening and tonight
highlights the short term forecast.
The 15-18 UTC operational and experimental HRRR iterations
continue to show strong run to run consistency in developing
convection across eastern Wyoming this afternoon, and propagating
this convection into southwest North Dakota by 02-04 UTC,
sustained by a strengthening low level jet and a resurgence of
upper level forcing ejecting out of the intermountain west upper
level low. This is supported by the greater 12 UTC CAM suite.
These HRRR iterations continue to depict in their 2-5 km updraft
helicity fields tracks of 75-100+ m2/s2 across southwest North
Dakota, supporting the potential for organized convection
possibly in the form of elevated low topped supercells to survive
from Wyoming into southwest North Dakota. Large hail and damaging
winds are the primary threats given the likely elevated nature of
these storms.
For Saturday, followed a blend of the 12 UTC global suite given
good agreement amongst the larger scale guidance for the
aforementioned upper level low to propagate into southwest North
Dakota by early Saturday evening. A dry slot is favored across
much of the south central for Saturday, with wrap around
stratiform precipitation across the far west, and potentially more
convective precipitation across the north central and James River
Valley.
.LONG TERM...(Saturday night through Friday)
Issued at 248 PM CDT Fri Sep 23 2016
Strong winds across the west Saturday night with a dry forecast
for the remainder of the period thereafter highlight the extended
forecast.
Given good agreement, followed a blend of the 12 UTC global
guidance suites for most fields. The nearly stacked low from the
short term is forecast to propagate across North Dakota Saturday
night. All ingredients will be available for strong winds on the
backside of the low, with a tight pressure gradient and strong
cold air advection aided by isallobaric forcing. 0.5 km winds
around 50 kts are forecast across the west, which will have to be
monitored for the next few models runs should a high wind watch
become necessary across the west for Saturday night into Sunday.
Thereafter, broad upper level ridging builds across the central
CONUS Tuesday through the remainder of next week, signaling a
drier pattern with near to slightly above average temperatures.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1040 PM CDT Fri Sep 23 2016
Widespread IFR/LIFR conditions in stratus, fog, rain showers and
thunderstorms will continue across western and central North
Dakota tonight. A brief improvement to MVFR-Low VFR remains in the
forecast for KBIS/KJMS late tonight into Saturday morning as dry
air works north-northwestward from South Dakota into the storm
system impacting our area.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...AYD
LONG TERM...AYD
AVIATION...NH
Area Forecast Discussion
National Weather Service Taunton MA
1009 PM EDT Fri Sep 23 2016
.SYNOPSIS...
A cold front will cross the region this evening, bringing lower
temperatures. A band of rain showers is also expected behind this
front later this evening into tonight, but amounts will be light.
Cool and dry weather will follow this weekend into early next
week. A slow-moving low pressure and cold front could lead to
some showers late next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
10pm update...
Widespread shra have developed in the deep moisture behind a cold
front which is currently moving into RI/CT and SE MA this hour.
1.5 inch PWATS are enough to allow as much as 0.20-0.30 of total
rainfall as these shra move through. Not as much as is needed of
course, but even this little bit well help. HRRR/RAP capturing
this band well, so POPs were updated toward their solutions. These
should be mostly offshore by about 2AM or so.
Previous discussion...
Short-term guidance, such as the HRRR and RAP,
continues to indicate a higher likelihood of at least some lightly
measuring showers. Will continue with a brief period of likely
PoPs this evening.
Band of rain showers will continue to press from north to south with
band of mid level frontogenesis/moisture behind a cold front. Much
cooler air will continue to work into the region tonight and northeast
winds will be a bit gusty along the coast.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Drier air will move in from the northwest, allowing for skies to
become mostly sunny during the morning. Mostly clear skies
continue through Saturday night.
Below normal temperatures during this time as well. If winds can
diminish enough, there is the remote possibility of some frost
across portions of the east slopes of the Berkshires Saturday
night, particularly in Franklin county. Will need to monitor this,
but think it is a low probability event at this time.
However, a fall-like
atmosphere will be in place with 850T between +3C and +5C. High
temps should still recover well into the 60s to near 70 given lots
of sunshine, but certainly be our first true taste of early fall.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Highlights...
* Dry and cool weather continues through Monday with patchy
frost possible for some locations Sunday night.
* Precipitation chances increase Monday night thru Wednesday
night, with a return to seasonable temperatures.
Overview and model preferences...
Omega block over the Mississippi Valley continues to translate east
and gradually deamplify through the middle of the upcoming week.
The 23/12Z model suite begins to diverge around 12Z Monday, with the
ECMWF notably weaker, and thus more progressive, with its handling
of the closed low over the Great Lakes. We leaned toward the slower
and more amplified GFS solution, given the interaction of several
pieces of energy, as the ECMWF may be breaking down the block too
quickly. But confidence in the details is below average, and will
remain so, until the models better resolve competing shortwave
energy interacting with the closed low.
Details...
Sunday and Monday...
Northwest flow aloft will keep the region dry during this time frame,
as Canadian high pressure crests across the region by Monday morning.
Given the combo of a dry airmass in place, as well as a decoupled
boundary layer, we anticipate ideal radiational cooling conditions
to occur Sunday night. Thus, we went below guidance on temperatures,
which may bottom out in the low to mid 30s for portions of the
region. In particular, the interior locations northwest of the Mass
Pike and I-495, as well as interior southeast Massachusetts, have
the potential for their first frost of the season. Otherwise, there
will be an increase in mid and high level cloudiness on Monday, as
a warm front approaches the region.
Monday night thru Wednesday... There is still uncertainty with the
timing of a cold front during this time frame, with the more
progressive ECMWF keying in on Tuesday morning, while the GFS holds
off until Wednesday afternoon. We leaned more toward the GFS, and
focused PoPs in the Monday night to Wednesday morning period. We
also kept consistency with the previous forecast, with the greatest
chance of precip focused in the late Tuesday thru early Wednesday
time frame, when the deepest moisture and strongest dynamics
coincide. This system does not have much in the way of moisture to
work with, as Precipitable Water values only rise to 1.5 inches, so
rainfall will be generally light. We also cannot rule out a rumble
of thunder along the south coast Monday night into early Tuesday, as
some elevated instability traverses this area.
Thu and Fri...
Still some uncertainty regarding how quickly the upper low departs
the region. We maintained NIL to low PoPs, especially considering
the amount of moisture along the back side of this feature.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...Moderate to high confidence. A period of MVFR CIGS and a band
of showers are likely behind a cold front. Northeast wind gusts of
20 to 25 knots expected along the coast.
Saturday...High confidence. Mainly VFR. Any leftover MVFR Cigs,
and perhaps some patchy early morning fog in the typical
locations, will improve to VFR by mid morning.
Saturday night...High confidence. VFR.
KBOS TAF...High confidence in TAF and trends, slightly lower
confidence in exact timing, particularly of showers.
KBDL TAF...High confidence in TAF and trends, slightly lower
confidence in exact timing, particularly of showers.
Outlook /Sunday through Wednesday/...
Sun thru Mon...High confidence. Predominantly VFR. Northwest
winds may gust to 25 kt near shore on Sunday.
Mon night thru Wed...Moderate confidence.
Localized MVFR conditions possible in showers, mainly Tue night into
Wed, with uncertainty with regard to timing. Otherwise VFR.
&&
.MARINE...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...High confidence. A strong cold front should result in a
period of northeast wind gusts up to 25 knots, and 3 to 6 foot
seas across our open waters, early this evening into the
overnight hours. Small craft headlines posted for all waters
except Narragansett Bay.
Saturday into Saturday night...High confidence. Leftover 25 kt
wind gusts diminish by mid morning as pressure gradient weakens.
However, small craft headlines will continue across our outer
waters into mid afternoon from leftover swell. These seas should
finally drop below small craft advisory thresholds by late
afternoon. Increasing north to northwest winds with a stronger
surge of colder air over the waters. Not confident there will be a
long period of sub advisory winds. So, will continue the small
craft advisory into Saturday night across the outer coastal
waters.
Outlook /Sunday through Wednesday/...
Sunday and Sunday night...High confidence.
Small craft advisory conditions prevail. Northwest wind gusts
around 25 knots Sunday, with seas 5 to 6 feet expected into
Sunday night.
Monday...
Conditions are expected to remain below Small Craft Advisory
criteria with high pressure building over the waters.
Monday night thru Wednesday...
An approaching storm system will lead to a period of southerly flow
over the waters during this time frame. Small Craft Advisory criteria
is possible during this period, however, the timing is uncertain.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ231>235-
237-251.
Small Craft Advisory until 11 PM EDT this evening for ANZ230.
Small Craft Advisory until 6 AM EDT Sunday for ANZ250-254>256.
&&
$$
SYNOPSIS...Belk/99
NEAR TERM...Belk/Doody
SHORT TERM...Belk
LONG TERM...99
AVIATION...Belk/99
MARINE...Belk/99
Area Forecast Discussion
National Weather Service Grand Forks ND
934 PM CDT Fri Sep 23 2016
.UPDATE...
Issued at 927 PM CDT Fri Sep 23 2016
Arc of showers and T continues across north half of the forecast
area in zone of strong warm advection/low level moisture
transport and on nose of 45kt low level jet. T mainly confined to
the DVL basin. Model guidance consistent in gradually lifting arc
northward towards the international border. Adjusted pops
accordingly with no other changes needed.
UPDATE Issued at 625 PM CDT Fri Sep 23 2016
This update adjusted pops based on current and expected radar
imagery using the HRRR which is handling current pcpn positioning
well. Also added fog to the Devils lake basin based on majority
model guidance.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 257 PM CDT Fri Sep 23 2016
Precipitation timing and how strong tomorrow`s convection will be
are the main challenges for the period.
Showers and thunderstorms stretch from northwestern ND into
central MN across our southwestern counties. This activity will
lift north and east throughout the rest of the afternoon into the
evening as isentropic lift along the mid level baroclinic zone
moves through. The main surface warm front is well to our south,
and the model have it moving slightly northward towards our
southern border later tonight. Both the high resolution models as
well as the synoptic runs have the most significant precip along
the mid level front and lifting north towards the Canadian border
throughout tonight. There is some weak elevated CAPE as seen on
the SPC meso page and the models have this continuing so will keep
the mention as showers with isolated thunderstorms. With the warm
front still mostly to our south there will be plenty of cloud
cover overnight and southeast winds will keep us mixed. Have some
mild low temperatures in the 50s to low 60s.
Tomorrow, the main upper low currently over the Rockies will
progress into western ND. The models are in decent agreement at
this point in the forecast and have the surface low moving up into
western to central ND during the day and starting to wrap up.
Southeasterly winds will continue for our area and the tongue of
warmer air will start to move into the southern Red River Valley.
There is still some question how much clearing there will be
during the day on Saturday, with most of the models having quite a
bit of moisture lingering in the area. At this point think there
will be at least some breaks and allow temperatures to get into
the 60s and 70s by afternoon. The NAM has a narrow band of surface
based CAPE moving into our western counties late in the day. Deep
layer bulk shear is better further west, but there could be some
30-40kts of 0-6km shear. Storms should start to redevelop by
afternoon in the western counties into the Red River Valley. Still
a lot of uncertainty, but there is enough CAPE and bulk shear
predicted by the models for a marginal risk tomorrow afternoon.
.LONG TERM...(Saturday night through Friday)
Issued at 257 PM CDT Fri Sep 23 2016
The primary challenge for the long term period will be timing and
placement of the dry slot associated with an area of low pressure
over western North Dakota. GFS and ECMWF are in similar agreement
with 00Z Sunday spatial characteristics of the surface low,
positioned from Sakakawea area to Medora with the ECMWF slightly
southwest at 00Z. However, GFS positions upper low further north.
A band of showers and embedded storms will develop sometime in the
late evening to overnight period. With subtle model differences,
leaning toward SREF solution for timing and placement...which
gives likely POPs over eastern zones and a sharp transition to dry
conds westward into the dry slot. Next challenge becomes track of
upper low and location of the wrap around moisture that should
eventually fill in western and northern zones later in the long
term period. Favored superblend solution for this portion of the
system`s evolution. Throughout the last three shifts monitoring
this system, models have been fairly consistent with no to low
CAPE values for this time period...and have once again revert wx
type grids back to the most likely scenario, predominant rain
showers with small potential for embedded thunder.
After the upper low/trough swings through, northern tier transitions
to NW flow pattern aloft with an amplifying ridge over the Canadian
rockies that slides over the Dakotas by Tue night. This will bring
dry weather the the middle portion of next week, with fall like
temperatures. Chances for precip increase again near the end of
next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 625 PM CDT Fri Sep 23 2016
Band of -ra will continue to propagate northward through the
evening and by 06z or so should be confined to the far north.
Expecting CIGs to lower to MVFR and IFR ranges most areas in wake
of rain band passage. Guidance also indicating potential for BR
over the DVL basin and added although not as low as guidance with
expected wind and cigs.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Voelker
SHORT TERM...JR
LONG TERM...Speicher
AVIATION...Voelker
Area Forecast Discussion
National Weather Service Grand Rapids MI
743 PM EDT FRI SEP 23 2016
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 315 PM EDT Fri Sep 23 2016
Fair weather will return tonight through Saturday and most of Sunday
with seasonably mild temperatures. A cold front will bring rain and
perhaps a few thunderstorms Sunday night into early Monday. A cooler
airmass will move in behind the front from Monday night
through Wednesday.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 315 PM EDT Fri Sep 23 2016
Primary short term fcst concerns involve timing rain into our fcst
area Sunday night.
An isolated light rain shower or sprinkle is still possible into
this evening mainly along the I-94 corridor closer to the nearly
stationary frontal boundary that extends across far northern IN/OH.
Otherwise quite a bit of cloud cover will linger overnight and some
patchy fog may develop during the early morning hours Saturday.
High pressure anchored to the northeast of our region will bring
fair weather Saturday through most of Sunday. It will be
seasonably mild in spite of easterly winds Saturday with high
temperatures reaching the middle 60s to lower 70s. It will be a
bit milder Sunday as winds veer to the southeast to south. This in
conjunction with some sun will help to boost max temps into the
lower to middle 70s.
The cold front approaching from the west will bring rain showers
Sunday evening that will become more widespread late Sunday night.
Convective potential late Sunday night is fairly low due largely to
frontal timing and weak instability.
.LONG TERM...(Monday through Friday)
Issued at 315 PM EDT Fri Sep 23 2016
Models are in decent agreement in showing the cold front moving east
of the forecast area Monday morning. Less of a risk for
thunderstorms exists as the main instability axis will be ahead of
this front. With a post frontal airmass moving in during the day on
Monday the highest potential for measurable rain will be in the
morning.
Some differences show up for Monday night into Tuesday. The GFS
wraps around considerably more moisture behind the departing system.
This occurs partly because the GFS is much cooler and the lakes add
moisture to this low pressure system. The new High Res Euro is
still dry as it is not as cool and it keeps the low further north.
Will hold onto the low risk for showers Monday night into Tuesday
given the spread in the models.
Ridging moves in for Wednesday into Friday. Thus any risk for rain
looks minimal. A moderating trend to the temperatures will occur as
the ridge builds east for the end of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 742 PM EDT Fri Sep 23 2016
This is a questionable forecast at best (just how fast the skies
will clear tonight). The current trend is toward clearing of the
lower clouds. Both MKG and GRR have had celling improve low MVFR
to VFR within the past hour. Similarly the BTL and AZO have gone
from IFR to low MVFR during the past hour. Both the RAP model and
NAM show the low level RH in the 1000 to 3000 ft layer drying out
but the RAP model is much slower showing the MVFR/IFR cigs holding
all night and not mixing out for the I-94 tafs sites till around
15z. Given the current trend I went for a quicker clearing but
time will tell how great of an idea that was.
Another issue is fog for the I-94 taf sites. BUFKIT profiles
suggest fog possible fog those taf sites. However the RAP and NAM
fog forecast does not show any fog tonight. I help on to the idea
of fog in the TAF for continuity I am on the fence with this. If
the sky can clear by 06z or so down by the I-94 taf sites I would
think the chance for fog is greater. If the low clouds hold that I
would think only MVFR fog is likely.
&&
.MARINE...
Issued at 315 PM EDT Fri Sep 23 2016
Northeast to east winds in the 5 to 15 kt range through Saturday
will result in minimal wave heights mainly in the 1 to 2 foot
range. Winds will veer to the se to south and strengthen somewhat on
Sunday out ahead of an approaching cold front. This will result in
building wave heights to at least 2 to 4 feet and potential for
wave heights to flirt with small craft criteria by Sunday
afternoon.
&&
.HYDROLOGY...
Issued at 1032 AM EDT Fri Sep 23 2016
Hydro concerns are minimal through the weekend, as little rain is
expected and river levels are around normal for the time of year.
Showers and thunderstorms are expected Sunday into Monday night with
additional rain possible Tuesday into Wednesday. Around 1 inch of
rain is expected and therefore rivers and streams should remain
below bankfull through the week.
&&
.GRR Watches/Warnings/Advisories...
MI...None.
LM...None.
&&
$$
SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...MJS
AVIATION...WDM
HYDROLOGY...63
MARINE...Laurens
Area Forecast Discussion
National Weather Service Gray ME
957 PM EDT Fri Sep 23 2016
.SYNOPSIS...
Showers will continue along a cold front through this evening
over southern New Hampshire and far southwestern Maine before much
cooler and drier air arrives for the weekend as Canadian high
pressure builds into the region. This will bring the potential for
frost or freezing conditions Saturday and Sunday nights...
especially over northern areas. Gradually moderating temperatures
are expected Monday before another approaching cold front brings
the threat for showers on Tuesday.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
10 PM Update...Band of showers is quickly exiting the southern
NH zones and will move out of the area within the next hour or so.
Otherwise, cool temperatures and clearing skies will prevail for
the rest of the region.
8 PM Update...Narrow band of rain showers are progressing across
southernmost NH as forecast and should exit over the next 1-3
hours. Therfore, very little changes to the going forecast.
530 PM Update...Have updated the grids for the next few hours
based on latest trends in observations and mesoscale model
guidance. The result was little change to the going forecast.
However, we did tighten up the PoP gradient a little bit across srn
NH for this evening based on latest radar mosaic loops and HRRR
guidance. Narrow stripe of showers is beginning to take shape
across Upstate NY to the NW of ALB. This area of showers is
expected to mainly affect Cheshire and Hillsborough counties this
evening.
Previous discussion...
High Impact Weather Potential: Patchy frost in the far northern
valleys possible.
Current Pattern: Water vapor imagery early this afternoon shows an
onslaught of northwesterly flow extending from Manitoba south and
east to a leading shortwave now pressing through New England. This
shortwave is interacting with a modest /although thinning/ moisture
plume along the east coast to produce multiple bands of showers as
it pushes south and east. Also of interest is an area of darkening
in water vapor imagery over western Ontario which represents another
upstream shortwave that will sharpen as it rapidly pushes southeast
into New England during the first half of the night. Beyond
this...sprawling 1030mb high pressure over northern Ontario will
begin to push toward the region...bringing a clearing/drying/
cooling trend to the area. Forecast concerns are thus focused on
precipitation potential through this evening...and temperatures as
the continental polar airmass arrives tonight.
Through Early Evening: Shower activity has dwindled markedly over
the past 1-2 hours...so through 6pm expect little more than a few
sprinkles/very light rain showers over southern areas with some
breaks in the clouds opening up over northern areas.
Tonight: High resolution near term guidance consensus has been
honing in on another period of more widespread shower activity over
southern NH and far southwestern ME this evening as aforementioned
shortwave over Ontario sharpens and interacts with H8 frontal zone.
The best window of opportunity for rain looks to be between 8pm
and midnight...generally south of a LEB-PWM line. This will
certainly help to boost meager rainfall totals in these areas thus
far...with another few tenths of an inch of rain quite possible.
Beyond this...cold and dry advection will be the rule with gradual
clearing from north to south as PWATs retreat back below 0.5".
Temperatures will fall rapidly...particularly with partial
clearing after midnight...with consensus lows in the upper 30s
north to mid/upper 40s south looking reasonable. Can/t rule out a
few patches of frost over the far north...but not widespread /or
confident/ enough to warrant a county-based headline.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
High Impact Weather Potential: Frost/Freeze Potential Saturday
Night.
Pattern: The short term forecast period will be dominated by
continued northwesterly flow aloft given highly amplified
trough/ridge/trough pattern across North America...with large
surface high over eastern Ontario Saturday morning remaining nearly
stationary through this forecast period. T8s start the period near
the freezing mark...and gradually settle lower by Saturday night
with these values representing -1 to -2 sigma departures from
climatology. PWATs will similarly be in the -1 to -2 sigma
range...promising little in the way of sensible weather through the
period. Forecast concerns will center around temperatures Saturday
night as the coolest night of the early fall season is expected.
Saturday: Longwave trough will continue to deepen along the east
coast of NOAM as sharp longwave ridging over the central portion
of the continent slowly builds and moves east. This will maintain
northwesterly flow through the column over our region...although
any significant cool advection will be over by daybreak. BUFKIT
profiles agree with CU rule suggestions from the guidance
indicating some SCT cumulus development in the mountains...with
very little in the way of cloudiness making it to the coast.
So...expect a mostly sunny day for most spots. T8s will only be
around +1-3C...so expect northern areas to remain in the
50s...with areas south of the mountains to reach the lower/middle
60s. Given the robust gradient aloft...expect northwesterly winds
10-20kts for the day...adding a bit of chill to the air.
Saturday Night: High pressure remains north and west of the area
with PWATs falling to around 0.25" in continental polar airmass.
Expect any afternoon cumulus to clear...with a chilly night in
store across the region.
Primary factor potentially limiting the chill will be an ongoing
breeze as 1000mb geostrophic winds remain 20-30kts overnight likely
keeping many locations coupled. Honestly...this looks more like a
freeze vs. no freeze situation with perhaps too much wind to support
frost. Given the breeze...have kept overnight lows a bit higher
than statistical guidance. Breeze will also restrict widespread
fog...but given how cool temperatures will be...some CT valley
locations will still probably see some patches.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Chance of High Impact Weather: Minimal.
Where for the last few months 500mb blocking was hard to come by
south of 50 N, we are finally starting to see sow blocks develop
that will bring troughs down in the 30-40 N range. The models do
not show stable blocking, but it is enough to bring temps to
around normal with some fluctuations either side of normal through
the long range. However, with the instability of the blocking,
systems will be mobile and not very strong, so any chance for a
soaking rain remains low through next week.
The cold air will continue to stream in Sunday, as 500 mb trough
works through in the morning. this air is very dry, but should
produce some clouds in the mountains Sunday, maybe become mostly
cloudy for a few hours. The coastal plain will see more sun in the
downslope as N-NW winds pick up in the 10-20 mph with some higher
gusts. Highs will be cool, and a few degrees below normal ranging
from the low to mid 50s in the mountains to the low 60s in srn NH
and along the ME coast.
Sunday night will turn out to be an very good rad cooling night as
sfc high builds in ands winds die off quickly with clearing
skies. Lows will range from the mid-upper 30s in the mountains to
the low 40s along the coast and in urban areas of the Merrimack
valley. This will bring the threat of frost to almost everywhereexcept
the immediate coast.
Light winds shift to the SW on Monday as the high shifts offshore
and it looks to be mainly a sunny day with highs a few degrees
warmer than Sunday, bring temps to around normal, generally in the
60s. The next chance for rain will be in the Mon night thru Wed
time frame as 500mb closed low tracks NE out of the great lakes
and drags a cold front across the region. The Euro is a little
progressive the fropa, ad moving the rain out by Tue night, with
the GFS lingering it. However, the Euro also merges the two closed
500 lows to our north and spins the resultant low back SW and
brings it just N of ME. This would result in cooler temps late in
the week than the GFS. Went with Superblend, which split the
difference which keeps temps around normal Wed-Fri, though if the
Euro is right, they would be cooler, and if the GFS they would be
warmer.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Short Term...
Summary: A cold front will push south of the region this evening
with high pressure building in it/s wake through Saturday and
remaining over the region through Saturday night.
Restrictions: Band of showers will bring MVFR restrictions northern
terminals...with CON/MHT/PWM/RKD likely seeing brief drops to MVFR.
Conditions improve to VFR as showers depart this evening...with
LIFR/IFR fog likely HIE/LEB...and possible CON/AUG. VFR for Saturday
/ Saturday night with the exception again being overnight fog
HIE/LEB.
Winds: Northwesterly winds 10g16kts this afternoon will diminish to
5-10kts /light and variable in the valleys/ for the overnight before
increasing to 12g20kts from the northwest for the day Saturday.
Northwest winds will diminish to below 10kts again Saturday night.
LLWS: No LLWS expected through Saturday night.
Thunder: Very slight chance of thunder MHT through 21UTC...but
chance not great enough to mention in TAF. No thunder beyond this
through Saturday night.
Long Term...Sunday could continue to some N-NW wind gusts in the
20-25 kt range, but VFR Expected Sun-Mon. Some showers are
possible Tuesday and Tue night, and could see a period of flight
restrictions ahead of cold front Tue afternoon and night.
&&
.MARINE...
Short Term...Strengthening northerly winds tonight will bring
winds/seas close to marginal SCA values for the overnight before
shifting northwest on Saturday...with winds/waves remaining near
marginal SCA values through Saturday night...after a brief lull
in the winds early Saturday.
Long Term...Borderline SCA possible Sunday in N-NW winds, but
winds diminish by Sunday evening and stay below SCA through Wed.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ154.
&&
$$
SYNOPSIS...Arnott
NEAR TERM UPDATE...Ekster
SHORT TERM...Arnott
LONG TERM...Cempa
AVIATION...Arnott/Cempa
MARINE...Arnott/Cempa
Area Forecast Discussion
National Weather Service Wilmington NC
1045 PM EDT Fri Sep 23 2016
.SYNOPSIS...
A cold frontal passage followed by modest and dry high pressure
will build southward across the Great Lakes and into the Mid-
Atlantic region this weekend. Moisture and rain chances will
return by Tuesday as the high moves offshore. The next cold front
will arrive from the west Wednesday, followed by autumn high
pressure accompanied by a dry and cool airmass.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As OF 1000 pm Friday...Could see a lingering shower along the
immediate coast but for the most part, via latest 88D mosaic
trends, the pcpn over land areas looks done. Could see activity
fire up over the adjacent Atl waters overnight, but for the most
part this activity will be drifting/moving with a southerly
trajectory. It could swipe Cape Fear or Cape Romain, but for the
most part land areas, away from the immediate coast, should stay
pcpn-free. Still a dilemma of whether to go with a predominate
stratus or fog night across the ILM CWA. The progged soundings are
not clear cut for stratus nor ground based fog. But given dewpoint
depressions, although not huge, within the 1k foot agl, will lean
toward more fog with indications of areas to widespread. Not very
much, if any, tweaking applied to overnight mins. If any, it was
towards a degree lower due to the lack of a low stratus blanket
across the FA.
PREVIOUS....................................................
As of 700 PM Friday...The Flood Watch has been cancelled do to
lack of additional pcpn expected.
The evening will feature a diminishing and dissipating trend to
the showers and isolated thunderstorms as witnessed by the latest
mosaic 88D trends and the latest near term models, HRRR RAP and
HiResWrf. Will indicate a lowering of POPs over land areas this
evening, leaving widely scattered activity over the adjacent Atl
local waters. Trajectories in the lower levels tonight indicate
the pcpn that develops over the Atl Waters will not have that
onshore and inland movement like the past 5 days. May see a few
shra develop nearshore and clip possibly Cape Fear or Cape Romain.
For the pre-dawn Sat hrs, low level moisture will remain avbl as
drier air aloft works its way southward. Will either see low
level stratus or ground based fog. Not bought on which wx
phenomena will dominate. For now, will include variable amounts of
clouds and patchy to areas of fog during the pre-dawn Sat hrs up
to a few hrs after daybreak. No tweaks to the min temps needed at
this time.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...As our low drifts farther south Saturday and
high pressure to the north begins to build in, the airmass should
dry appreciably from the top down. Precipitable water values in the
1.8 to 2.0 inch range today should fall to 1.5 inches Saturday
afternoon and to 1.25 inches Saturday night. Using 850 mb relative
humidity as a guide, I am limiting showers Saturday afternoon to
just the seabreeze convergence zone of Horry and Georgetown counties
in South Carolina, anticipating the airmass will become too dry
elsewhere to overcome the convective cap. With skies becoming mostly
sunny by late morning, highs should reach the upper 80s inland, 82-
86 closer to the coast.
High pressure north of the Great Lakes Saturday will build southward
down the Mid-Atlantic coast on Sunday. This should push a cold front
through the coastal Carolinas early Sunday. With a building ridge
aloft and meager moisture, this front will probably come through dry
with only an increase in low-level wind speeds expected. Winds
behind the front Sunday should become east-northeasterly, perhaps
picking up enough Atlantic moisture for scattered showers to develop
and advect onshore. Since this is heavily modified Canadian air that
will have spent a thousand miles or so over the warm western
Atlantic, low-level lapse rates should be steep which may help
support these shallow convective showers.
Given the significant post-frontal influence off the Atlantic, I am
not forecasting Saturday night and Sunday night low temperatures to
fall quite as low as recent MOS guidance would indicate,
particularly along the coast.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...High pressure will be to our north on
Monday but rather than a wedge-like NE flow wind will remain out
of the E. This will keep shower chances in the forecast as
Atlantic moisture is handily advected ashore. They may tend to
favor coastal areas though as mid level ridging keeps the upper
levels of the column quite dry. This onshore flow will turn more
southerly with the approach of a cold front on Tuesday, its
passage slated for Tuesday night. Wednesday and Thursday could
feature the strongest cool advection we`ve seen in a while and
bring some unseasonably cool weather with Thursday night possibly
slipping below 60 away from the coast. A wedge then sets up on
Friday continuing the cool weather.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
As of 00Z...Expect a mixture of VFR/MVFR/IFR tonight through
Saturday morning due to passing low cigs, isolated showers and
developing fog towards morning. Otherwise expect VFR with
isolated showers on Saturday.
Latest guidance and weather pattern trend continue to suggest
potential for widespread fog late overnight into the early
morning hours. Thus have noted in going forecast with light
winds and passing low cigs. After daybreak, expect conditions
to gradually improve to VFR and continue through the remainder
of the TAF period. Northeasterly winds will increase to 5 to 8
kts, becoming east- southeasterly in the afternoon hours.
EXTENDED OUTLOOK...Chance for SHRA/TEMPO MVFR Sunday.
Chance for SHRA/TSRA Tue through Wed. Otherwise expect VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1015 PM Friday...Rather weak sfc pg and somewhat diffuse
pressure pattern to continue across the local waters due to the
weak sfc low now well south of the ILM CWA. Will continue with
the NE wind directions and speeds at 5 to 10 kt. The pcpn
coverage over the local waters has shrunk a good deal this evening
but could temporarily peak back up mainly over the offshore waters
south of Cape Fear during the pre-dawn Sat hours. With pcpn
movements slated to have mainly a southward trajectory, the
majority of the pcpn will likely remain over the offshore waters.
Significant seas will be totally a function of the 2.0 to 3.5 foot
e to ese ground swell at 11 to 12 second periods from Tropical
Cyclone Karl. The higher end of this range of swell will occur
north of Cape Fear, with 3 to 4 foot significant seas being
fcst...and with 2 to 3 foot south of the Cape.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...Surface high pressure north of the Great
Lakes on Saturday will build southward down the Mid-Atlantic
coast Sunday. This should push a cold front through the coastal
Carolinas early Sunday. Winds both ahead and behind the front will
be northeasterly, and since the front will come through dry the
only change heralding the front`s arrival will be an increase in
wind speed. Winds Saturday and Saturday night around 10 knots
should increase to around 15 knots for Sunday. These winds, in
combination with swells from Tropical Storm (or Hurricane) Karl
out near Bermuda, will build seas to 3-4 feet with some 5-footers
probably lurking not too far from 20 miles from shore near Cape
Fear.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 300 PM Friday...Monday starts off with easterly winds as
high pressure is centered well to our north. This flow will then
veer as the day wears on as the high progresses eastward and a
cold front approaches from the northwest. This boundary comes
through Tuesday night and it will usher in an increasingly strong
NE surge of cooler air. Ahead of the front on Monday seas will be
quite manageable and any prefrontal increase in seas Tuesday
should be quite gradual. This may not hold true with and
following FROPA Tuesday night into Wednesday where headlines may
become necessary.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...TRA
NEAR TERM...DCH
SHORT TERM...TRA
LONG TERM...MBB
AVIATION...SGL
Area Forecast Discussion
National Weather Service Lincoln IL
833 PM CDT FRI SEP 23 2016
.UPDATE...
Issued at 833 PM CDT Fri Sep 23 2016
Upper level ridge building into the area will provide subsidence
for clear skies tonight with just some scattered high clouds
possible mainly north of I-74. Meanwhile...a frontal boundary
moved in from the north earlier today and has made very slow
progress since arriving roughly at a Schuyler county to Paris
orientation west-east across central IL. Main impact of the
boundary should be a good chance for some fog to form overnight
along and behind the front in the cooler moister air with
dewpoints in the upper 60s to around 70 along with good cooling
due to the clear skies. Even to the south of the
boundary...dewpoints this afternoon were still fairly moist in the
mid 60s and could result in patchy fog with similarly effective
radiative cooling. Otherwise...expect lows to reach the mid 60s
tonight. No major updates needed to the forecast tonight.
&&
.SHORT TERM...(This evening through Saturday)
ISSUED AT 310 PM CDT Fri Sep 23 2016
A surface boundary/back door cold front just south of I-74 this
afternoon will continue to slowly sag sw across central IL into
tonight, with 1029 mb surface high pressure over Ontario ridging
into the Great Lakes region. Latest run of HRRR is now showing
some convection from I-74 northeast late this afternoon and early
evening but feel its coverage is too high and earlier runs of HRRR
were dry. Current radar mosaic shows just isolated very light
showers ne of Vermilion county IL which latest RUC model shows, so
will keep pops at 10% over northeast CWA through 00Z/7 pm today.
Dewpoints in the 60s across CWA and models show some increasing
low level moisture near and northeast of the front tonight
especially overnight into early Saturday morning allowing patchy
fog to form with light wind regime.
The latest forecast models continue to have a strong upper level
ridge over IL on Saturday with 500 mb heights around 589 dm. This
should bring another very warm summerlike day to the area with
highs 85-90F and dewpoints in the mid to upper 60s.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 310 PM CDT Fri Sep 23 2016
The main focus for this forecast cycle will be the frontal passage
and associated precipitation for this weekend. The 12z models seem
to have better agreement on the a more progressive theme to the
upper level pattern progression. The Canadian NH no longer cuts off
a low behind the front, for later passage mid-week. The consensus
indicates the occluded surface and upper low pressure centers will
move from the western Dakotas Saturday afternoon northeast into
Manitoba and western Ontario by Sunday evening. Then the upper
trough is projected to deepen toward the southeast, into the central
Great Lakes region. This will provide the reinforcing push of cooler
air for our mid-week cool down.
As for the sensible weather during this scenario, we are looking for
increasing clouds Saturday night as the cold front moves half way
across Iowa. We included a narrow ribbon of slight chance PoPs along
our far western counties in Knox, Fulton and Schuyler counties. The
strongest forcing for precip will generally remain north of our
forecast area on Sunday as the surface and upper lows lift into
western Ontario. As a result, the front circulation and low level
moisture convergence will most likely be weakening during FROPA
Sunday afternoon and early evening. Support for any thunderstorms
will come from high boundary layer moisture with dewpoints around 70
in the pre-frontal air mass. Instability params will support a line
of storms, with MUCAPES of 1500-2200 J/kg Sunday afternoon. Bulk
shear will be marginal, in the 20-25kt range. The better agreement
on frontal timing has increased confidence in precip on Sunday
afternoon/eve, and PoPs were increased to Likely /60-70%/ north of
I-72, progressing from west to east between Noon and midnight.
Precip chances will linger into Monday as a secondary lobe of energy
rotates through the upper trough before it departs to the east on
Tuesday. A much cooler and drier air mass will settle into Illinois
for Tuesday through Thursday. Highs will be below normal in the low
70s on Tuesday, then warm to near normal in the mid to upper 70s for
Thursday, with upper 70s across the board on Friday. No
precipitation is expected from Monday night through Friday, and
possibly into next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 613 PM CDT Fri Sep 23 2016
Dry conditions will continue over the next 24 hours for the
central IL terminals as a high pressure ridge builds over the
area. At the surface a weak frontal boundary has pushed into the
area from the north bringing additional moisture and a shift to
northeast winds. Behind and along the boundary the moisture should
be adequate for fog to develop overnight. This boundary looks to
stall in the vicinity of I-72 overnight, so have included
conditions dropping to IFR vsby for the I-74 terminals KPIA-KBMI-
KCMI while only MVFR vsby for the I-72 terminals KSPI-KDEC due to
uncertainty in the impacts there. Fog should diminish by 14Z.
Scattered cumulus cloud cover around 5000 ft AGL should develop
by late morning Saturday across the area.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...Onton
SHORT TERM...07
LONG TERM...Shimon
AVIATION...Onton
Area Forecast Discussion
National Weather Service Pueblo CO
807 PM MDT FRI SEP 23 2016
.UPDATE...
Issued at 803 PM MDT Fri Sep 23 2016
Updated to expire red flag warning. Winds are still strong, but
humidity has increased above 15 percent most areas. Storms firing
in moist air over the plains east of the dry line, though modest
instability has kept intensity below severe levels so far. Still a
threat of a few severe wind gusts as storms fly north at 40-50
mph, with threat ending 05z-06z acording to latest HRRR.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 301 PM MDT Fri Sep 23 2016
...A variety of high impact weather to continue across southern CO...
An intense upper low over NW UT/SW WY will continue to lift
northeastward with trailing trof axis swinging across southern CO
during the evening hours...a little behind earlier model
projections. This will put the brunt of the energy crossing the
eastern mountains between 00z and 03z with strong downward forcing
coming in quickly behind. Dry line has been slow to sharpen
up...though in last hour dew point at COS plummeted from 39 to 15
degrees F...so once winds shift out of the southwest to west...it
shouldn`t be too long before rapid drying takes place. Winds have
been gusting to 40-50 mph at times and this will continue through
the evening and overall Red Flag Warning still looks on track. To
the east of the dryline...high res models are developing a broken
line of thunderstorms between 4 PM and 5 PM. Dew points in the lower
50s yield mixed layer CAPE values of 1000 J/kg in SPC meso analysis.
Deep layer shears will be running around 30-40 kts...so potential
for one or two severe thunderstorms across the eastern counties
still looks possible. Storms will be moving rapidly north
northeastward with HRRR showing most of the activity done by 06z.
Given high based nature to thunderstorms...main threat still looks
to be winds over 60 mph and hail to around 1 inch in diameter.
As the upper low lifts northeastward should see activity tail off
from west to east...though northern portions of the Continental
Divide may continue to see off and on snow showers through the
overnight hours. Cold front moves in overnight...and a widespread
freeze still looks likely for the San Luis Valley. Have upgraded the
freeze watch to a freeze warning. Temperatures will be cooler
elsewhere...but winds should keep temperatures from dropping too
close to the freezing mark.
Saturday will be cooler behind the front...though secondary push of
cooler air will approach the Palmer Divide during the afternoon.
Just enough moisture will be present along the CONTDVD and northern
portions of the southeast mountains for some isolated to scattered
showers and thunderstorms to redevelop...but overall...any
precipitation looks light at this point. -KT
.LONG TERM...(Saturday night through Friday)
Issued at 301 PM MDT Fri Sep 23 2016
...Feeling more like Fall on Sunday...
The global models have come into better agreement today. The
strong upper low moving through W CO today will split this
weekend, with most of the energy lifting off to the NE. The base
of the trough will cut off over W NM, then slowly eject to the NE
during the mid to latter portion of the coming week.
Sat night...the main low will be well north of our area...over
the Nrn High Plains, while the trough axis is moving through E CO
and the base of the trough beginning to split and cut off over NM.
This will be the coldest air mass of the extended, with H7 temps
getting down to around zero degrees over Teller County by early
Sun morning. So...there could be a few snow showers above 9000
feet early Sunday, and possibly some light localized accums...but
significant or widespread snow appears unlikely, and the latest
model trends are for less QPF over the area.
Main impact from this system will be considerably cooler wx on
Sunday, with high temps only in the 60s for the Plains and 40s
for the mts. WIll clear out pretty quickly Sun morning-afternoon,
leaving our area with building high pressure from the west, which
will keep us dry through at least Tuesday. Temps will gradually
increase during this time period.
By early Wednesday, the cut-off low to our south will finally
begin moving into SW CO. This system will be much weaker than the
current upper low, and with the Southwesterly trajectory, will
also be quite a bit warmer aloft. So, snow levels will likely stay
pretty high for the last week in September, generally above 12000
feet. Showers will be on the increase, especially for the latter
part of Wed into early Thu. Have left mention of TS in the grids
for this period since there will be some modest instability with
the upper low. But for the balance of the forecast period,
climatology does not favor widespread TS, so left any precip as
Showers for the rest of this period.
Once the second upper low moves through from the SW, our area will
likely stay in an unsettled pattern with shortwaves moving through
the Central Rockies. Current forecast assumes southwest flow over
the CWA, so temps will remain generally above average. Rose
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 301 PM MDT Fri Sep 23 2016
South winds 25-40 KTS will shift around from the west during the
late afternoon and early evening and remain gusty through 03-04z
before gradually diminishing. TAF sites will remain VFR...but
CONTDVD region will see off and on IFR to LIFR conditions in SHRASN
through the early evening. Isolated TSRA will be possible to the
east of the KLHX this evening...with the potential for a strong to
severe storm or two through the evening hours. Clearing will take
place through the evening...though some IFR to MVFR stratus may
persist along the CONTDVD through Saturday morning. Winds will be
much lighter on Saturday with another cold front expected to drop
through the plains late Sat afternoon and early Sunday evening. -KT
&&
.PUB Watches/Warnings/Advisories...
Freeze Warning from midnight tonight to 9 AM MDT Saturday for
COZ069>071.
&&
$$
UPDATE...PETERSEN
SHORT TERM...KT
LONG TERM...ROSE
AVIATION...KT
Area Forecast Discussion
National Weather Service SAN ANGELO TX
637 PM CDT FRI SEP 23 2016
.AVIATION...
/00Z TAFS/
Current VFR conditions will deteriorate to MVFR after midnight
tonight with most locations settling between 1500 and 2000 feet.
Expect the MVFR CIGs to persist through most of the morning
Saturday before lifting to VFR by around 18Z. Winds will be light
and southeasterly tonight, becoming more southerly around 12 knots
tomorrow afternoon with gusts to around 20 knots. 20
&&
.PREV DISCUSSION... /issued 349 PM CDT FRI SEP 23 2016/
SHORT TERM...
(Tonight and Saturday)
The primary heavy rainfall event starts to occur Saturday Night, so
the long term part of the discussion will deal with those concerns.
For tonight, visible satellite shows some agitated cu across much of
West Central Texas, but the latest HRRR is showing only a few
isolated showers and storms developing this evening. This pretty
well covered in the current forecasts so left that part of it alone.
Convection will likely develop tonight to the west across the South
Plains and Permian Basin as lift ahead of the large upper level
trough axis begins to move into West Texas. These storms should
slide east and increase in coverage Saturday afternoon. Have
increased rain chances across the northwest Big Country, mainly
north of a Sweetwater to Throckmorton line for Saturday afternoon.
Areas farther south will wait for Saturday Night and beyond for
their best chances.
As for temperatures, mild again tonight as low clouds develop across
much of the area by morning. Increasing cloud cover during the day
on Saturday will begin to cut into afternoon highs. Still, enough
sunshine in the afternoon for upper 80s and lower 90s, the hottest
day we will likely see for the next week.
07
LONG TERM...
(Saturday Night through next Friday)
The main focus is with the likelihood of heavy rainfall and the
threat for flooding this weekend into Monday.
By Saturday evening, an upper low is forecast to be over the
Montana/ North Dakota border, with an upper trough extending south
across western New Mexico. The GFS and ECMWF are in better agreement
with the development of a closed low over southwestern New Mexico
Saturday night. This low is progged to drop slowly south-southwest
into Mexico on Sunday, and then retrograde slowly Sunday night into
northwestern Mexico by Monday evening. With the northern part of the
aforementioned trough progged to move east across the northern
Plains on Sunday, trailing portion of a cold front is progged to
move south into our northern counties Sunday afternoon, and then
to make slow progress south through the rest of our area Sunday
night and early Monday morning.
Abundant moisture will be in place with precipitable water values
1.5 to 2 inches across our area, with low-level moisture influx from
the Gulf of Mexico, and mid-high level moisture incorporated into
the system from the eastern Pacific.
In the Saturday night to Monday time frame, several disturbances
aloft are progged to rotate around the eastern periphery of the
upper low and into the western half of Texas. With this setup,
anticipate several rounds of showers and thunderstorms with
increased coverage and heavy rainfall. In addition, the slow-
moving frontal boundary will provide an additional focus for heavy
rain. Rain chances will ramp up Saturday night and continue
through Sunday night, with likely PoPs extending through Monday.
From Saturday night through Monday, widespread rainfall totals of
2-4 inches will be likely, with locally higher amounts possible.
While our area can take some rain initially, expect multiple rounds
of convection to saturate the ground and lead to excessive runoff/
flooding. A flash flood threat will also exist. We are monitoring
this developing wet weather situation closely, and a Flash Flood
Watch may be issued if the next set of models continue to show this
setup for our area.
Temperatures will be much cooler at the beginning of the week,
especially on Monday. Rain chances will be lower, but still present
in parts of our area Tuesday and Wednesday. Later in the week,
temperatures are expected to warm back into the lower to mid 80s for
highs (Thursday and Friday), when an upper level ridge tries to
build back into our area.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 71 88 69 77 / 20 50 70 80
San Angelo 73 92 71 78 / 10 40 70 80
Junction 73 91 72 82 / 20 30 60 70
Brownwood 71 89 71 80 / 20 40 50 80
Sweetwater 69 88 69 73 / 20 60 80 90
Ozona 72 89 70 78 / 10 40 70 80
&&
.SJT Watches/Warnings/Advisories...
None.
&&
$$
Area Forecast Discussion
National Weather Service Bismarck ND
458 AM CDT Sat Sep 24 2016
.SHORT TERM...(Today and tonight)
Issued at 450 AM CDT Sat Sep 24 2016
The mid level low was on the forecast track of the NAM and it was
followed more closely this forecast cycle. Temperatures today
will have a wide range from the cloudy, showery Divide County to
where the sun breaks out in Logan County.
Mid level low was moving through Wyoming this morning toward North
Dakota with its surface feature out ahead. As the circulation
approached, showers were moving more northwest, caught in the
circulation. With no returns upstream and the short term hi res
HRRR showing no showers for much of the morning, have dropped pops
all but the west and north. The central part of the forecast area
breaks into some sunshine this afternoon in the dry slot. CAPE and
instability increase in warm air advection and support
thunderstorm development in central North Dakota. As the storms
move northeast they`ll encounter increasingly unstable air and sub
severe hail and wind will become a concern. Any severe weather
should be very limited in the Bismarck NWS forecast area and
confined to low end severe if it reaches that level at all.
Concern for tonight is the next short wave moving through the
circulation with another round of showers, maybe a rumble of
thunder. As the surface low moves through the wind shifts and
increases. Bufkit soundings for southwest North Dakota show steady
30 to gusts 45 mph of wind will reach the surface. There is
higher wind than that aloft and it is possible this could mix
down to the higher terrain southwest. For now will go with
advisory for winds 30 to 45 mph and keep the high wind warnings
in our toolbox until we see the whites of its eyes. Any showers
will act to mix that higher wind to the surface so we`ll have to
monitor closely.
.LONG TERM...(Sunday through Friday)
Issued at 450 AM CDT Sat Sep 24 2016
Showers taper off west early Sunday as the cyclone pulls away and
becomes an open wave, but the wind will be left behind. Have
continued the wind advisory for the southwest through Sunday but
wouldn`t be surprised if the Sunday day shift can cancel it a bit
early. Generally cooler and windy to very windy Sunday, but with
increasing sunshine from the west.
After that an H5 ridge builds over the area and much of the coming
work week is dry and mild with lows in the 40s and highs 65 to 75.
The coolest night starts the period, Sunday night-Monday morning,
with a lot of places dipping into the upper 30s.
The next rain producer looks to come in late in the week and into
next weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 100 AM CDT Sat Sep 24 2016
Widespread IFR/LIFR conditions in stratus, fog, rain showers and
thunderstorms will continue across western and central North
Dakota through the overnight into Saturday morning. A brief
improvement to MVFR to low end VFR remains in the forecast for
KBIS this morning as drier air works north-northwestward.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 5 PM this afternoon to 5 PM MDT Sunday for
NDZ040-041-043-044.
&&
$$
SHORT TERM...JPM
LONG TERM...JPM
AVIATION...JJS
Area Forecast Discussion
National Weather Service Wilmington NC
329 AM EDT Sat Sep 24 2016
.SYNOPSIS...
High pressure today will bring dry weather and above normal
temperatures. A back door cold front will be accompanied by
slightly cooler temperatures and increasing shower chances late
this weekend and into the early week. A more robust cold front
will cross Tuesday into Wednesday with continued rain chances.
Drier and potentially much cooler air will build southward for
late in the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Saturday...We will finally experience drying today as
weak ridging develops ahead of a backdoor cold front which will be
approaching the area tonight. Offshore showers are generally not
expected to reach the beaches this morning. A resultant boundary
should become rather pronounced, but given the lack of moisture
depth to support convection, will keep POPs below threshold. A good
deal of sunshine is expected and this will make for summer like
highs today, upper 80s to around 90. Lows tonight will be in the
upper 60s to around 70. Model soundings are showing considerable
saturation near ground level overnight and with cloud cover not
expected to increase until late, from N to S, will include at least
patchy fog at this time.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 300 AM Saturday...A backdoor cold front will move slowly
across the area on Sun. Moisture convergence along this front will
allow columnar moisture to increase both in magnitude and depth as
onshore flow deepens. Mixed layer CAPE values also project
increasing instability. However, there will be no appreciable upper
level support with ridging aloft. Thus, will only include isolated
to scattered showers and thunderstorms in the forecast favoring the
afternoon and eve hours for the best coverage.
High pressure centered across New England Mon morning will shift
offshore through the remainder of Mon and Mon night. This will veer
the low level flow across the eastern Carolinas from E to SE. Weak
shortwave energy will lift N toward the forecast area Mon and Mon
night coincident with an inverted trough along the coast. Depth of
moisture looks rather shallow. Still, POPs are warranted and will
include isolated to mainly scattered during this time.
Highs will be slightly cooler on Sun, mainly mid 80s with lower 80s
more common on Mon. Lows will be in the upper 60s to around 70.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 300 AM Saturday...Deep early fall trough will dig across New
England mid-week pushing a slow moving cold front through the
Carolinas. This front will drag slowly southward Tuesday into
Wednesday, and while total forcing is not very strong thanks to the
primary vorticity center moving east, increasing moisture and
instability combined with at least weak PVA within the stretching
lobe of vorticity will drive showers with isolated tstms the first
48 hours of the extended. This front looks to provide a true air
mass change for the latter half of the week, as 850mb temps drop to
10-12C, and much drier air advects down the coast within large high
pressure expanding from the northeast.
Must note that the 00z/24 ECM guidance has changed drastically -
stalling the upper low across the OH VLY - with height falls and a
pressure trough locally continuing rain chances right into the wknd.
While this is new to the ECM, it mimics at least somewhat previous
runs of the GFS from 24-48 hours ago, which begs the question
whether this will be a trend towards that more amplified solution. At
this time will favor the faster solution of the GFS and preferred by
WPC which would bring cooler and drier weather in here by week`s end.
After above climo temps on Tuesday, MOS numbers suggest slightly
below normal temps for both max and min by the end of the week, with
lows possibly dropping into the 50s for the first time since the end
of May.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
As of 06Z...IFR likely overnight, but moderate nocturnal boundary
layer winds may cause periods of VFR as well.
Fog has been spotty so far across the area, but with dewpoint
depressions approaching 0, and winds decoupling at the surface,
expect fog to become more widespread in the next few hours. Local
UPS Fog procedure has widespread fog away from the coast, and with
the wet ground in place, expect this to occur. The caveat to this
is VWP winds showing up at 20-25 kts presently, well above any
available guidance. The RAP soundings are closest to reality this
morning and are preferred, and these winds could lift the fog into
an IFR stratus deck, especially at the coast. Of course, if the
winds remain too strong stratus may be fractured leaving transient
VFR, and this will need to be monitored for possible AMDs. A few
showers developing offshore are not expected to affect the
terminals, and have shown IFR at all sites through daybreak
Saturday with very light north winds.
IFR will break an hour or two after sunrise, with VFR expected
thereafter. A much drier column forecast for Saturday will preclude
any showers, and only sct diurnal CU is forecast beneath winds
becoming easterly at less than 10 kts. More fog/stratus is possible
Saturday night, but any restrictions are expected beyond this valid
period.
EXTENDED OUTLOOK...Chance for SHRA/TEMPO MVFR Sunday.
Chance for SHRA/TSRA Tue through Wed. Otherwise expect VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Saturday...Weak ridging will develop today ahead of an
approaching backdoor cold front which is expected to move slowly
through the area on Sun. isolated to scattered showers are expected
to dwindle and come to an end this morning. Winds will be from the
NNE or NE at 10 to 15 kt. Seas will remain 2 to 4 ft with most of
the 4 ft seas near Frying Pan Shoals. A robust 10 to 12 second
easterly swell will be present.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 300 AM Saturday...A backdoor cold front will move slowly
across the waters on Sun. NE to ENE winds Sun and Sun night will
be up to 15 to 20 kt. Seas will be mainly 3 to 4 ft with some 5 ft
seas across the outermost northern waters. High pressure ridging
across the waters from the N is expected to push eastward and with
that, winds should veer from E Mon morning to ESE or SE. Wind
speeds should be no higher than 10 to 15 kt. Swell energy is
expected to weaken Mon and Mon night and seas should drop about a
foot.
LONG TERM /TUESDAY THROUGH WEDNESDAY/...
As of 300 AM Saturday...Slow moving cold front will be the primary
weather concern through mid-week as it drags NW to SE across the
area. Ahead of this boundary, broad high pressure will create light
E/SE winds over the waters, with the direction slowly veering to the
SW and eventually N as FROPA is slated by Wednesday morning. Speeds
will remain light much of Wednesday before a NE surge develops late
in the period, increasing winds to 10-15 kts. Although wind speeds
will create only limited amplitude in any wind-wave groups until a
NE 4 sec wave develops late, continuing 10-12 sec swell from distant
tropical systems will allow seas to persist at 2-4 ft through the
period.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...JDW
NEAR TERM...RJD
SHORT TERM...RJD
LONG TERM...JDW
AVIATION...JDW
MARINE...RJD/JDW
Area Forecast Discussion...UPDATED
National Weather Service Marquette MI
558 AM EDT SAT SEP 24 2016
.UPDATE...
Issued at 557 AM EDT SAT SEP 24 2016
Showers over western Lk Superior getting a bit too organized to just
have slight chance pops over western cwa this morning. Blend of HRRR
and ESRL HRRR and RAP suggest showers continue east where h7-h5 RH
is maximized and on edge of stronger h85 warm air advection. Showers
then slide ene across the Keweenaw Peninsula rest of this morning.
Now even some potential for rain as far east as north central Upper
Michigan this morning. Main change for now was to increase pops
across Keweenaw to likely. Just looking at a few hundredths of rain
but certainly enough to get the ground wet. Placed chance pops over
rest of western cwa next few hours and based on radar trends did
bring slight chances to the ncntrl before they lift out across Lk
Superior. No change to slight chances along WI border. Tweaked temps
down through the morning with the higher rain chances and thicker
cloud cover. Still expect skies to try to clear some possibly by
early aftn over the west half. &&
.SHORT TERM...(Today and tonight)
Issued at 349 AM EDT SAT SEP 24 2016
Sharp upper level confluent northwest flow is present aloft over the
Great Lakes this morning between sharp ridge over central Conus and
broad trough over eastern Canada. Warm and moist air ahead of strong
Upper low over CO/WY is driving clusters of shra and tsra from
western KS and Neb and also over the western Dakaotas into southern
Manitoba where h85 warm air advection is strongest. The confluent
flow is resulting in large area of sfc high pressure from northern
Manitoba to the Upper Great Lakes. Even with the sfc high nearby,
mid and high clouds are increasing in the warm air advection pattern
aloft. Enough moistening/isentropic ascent on the 305k sfc /800-
750mb/ from northern MN to far western Upper Michigan and northern
WI to support light echoes on the regional radar and multiple obs
are showing light rain is indeed occurring under some of these
echoes. Strongest h85 temp advection remains northwest of Lk
Superior today so once the isentropic ascent and mid level moisture
begins to wane expect the sprinkles or light showers to do the same.
Have small pops over west/southwest through 14-15z then have it dry
the rest of the day with minimal additional forcing and mid levels
drying out. Mostly cloudy this morning but could see filtered
sunshine this aftn. H85 temps bounce up over 10C over the west
though looks like we will only mix to 900-875mb. Overall expect
highs in the mid-upper 60s but could see low 70s over the west.
Center of sfc high slowly moves east tonight as low pressure system
in the plains this morning /tied to the upper low/ lifts toward
southern Manitoba by daybreak on Sun while occluded front crosses
northern MN. Upper level ridge axis remains over Upper Michigan most
of the night while upper trough crosses the Dakotas. A lot of dry
air around in low levels so think the interior central and east
could see temps into the 40s inland where winds try to decouple. 50s
elsewhere as clouds increase and as southeast to south winds stay up
ahead of the front. Forecast soundings did not look promising for
any rain to reach far west by 12z Sun. However, when looking at
where the shra/tsra are occuring this morning on edge of higher h7-
h5 RH/higher pwat and fact this gradient of moisture will be pushing
over far west cwa 09z-12z tonight did bring chance pops to the far
west at that time. SI/s also nearing 0c so retained slight chance of
tsra. A lot of tsra is occurring this morning on the moisture
gradient so feel good about having at least a small mention in there
late tonight. Over most of the rest of the cwa though it should stay
dry though at least 12z with the lingering ridging aloft and dry low-
levels.
.LONG TERM...(Sunday through Friday)
Issued at 317 AM EDT SAT SEP 24 2016
Nam has a trough in the northern and central plains 12z Sun with a
shortwave ridge over the upper Great Lakes and ridging in the
western U.S. The trough moves east into the upper Great Lakes Sun
night into Mon and then moves into the lower Great Lakes Mon night.
Deeper moisture and 850-500 mb q-vector convergence arrive on Sun
and last through Sun night with Mon having the wraparound part of
system affecting the area. Did not make too many changes to the
going forecast and have likely pops overspreading the cwa Sun into
Sun night and then chance pops on Mon with wraparound part of storm
coming through.
In the extended, GFS and ECMWF are showing much better agreement at
96 hours with both having a closed 500 mb low east of Lake Superior
in Ontario 12z Tue and ridging into the Rockies and southern plains.
By 12z Wed, the trough is over the lower Great Lakes and the ridge
is into the Plains. The 500 mb ridge then builds into the upper
Great Lakes 12z Thu into Fri. Confidence is now a bit higher due to
better agreement between the GFS and ECMWF now. Temperatures look to
be above normal for this forecast period. Also looks a bit drier now
starting Wed afternoon through Friday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 132 AM EDT SAT SEP 24 2016
Despite some mid/hi clds invading the Upr Lks to the ne of a slowly
aprchg warm fnt, a dry e veering sse flow arnd hi pres moving e thru
Ontario wl result in predominant VFR conditions at the TAF sites
this fcst period. Although there could be a --shra at IWD early this
mrng under some thicker clds, there wl be no vsby restriction.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 349 AM EDT SAT SEP 24 2016
East to southeast winds less than 20 kts today, then southeast winds
increase Tonight into Sun as high pressure moves toward Quebec and
New England and a low pressure system lifts across Mantioba to
northern Ontario. Winds may gust as high as 30 kts Sun into Sun
evening over north central and eastern sections of Lk Superior. The
low will move east of the region Mon into Tue and a cold front will
cross Lk Superior. Winds shifting to the west-northwest will
increase to 20-25 kts on Mon and could reach 30 kts Mon afternoon
into Mon night. Northwest winds to 25 kts continue on Tue then winds
diminish to 20 kts or less by Wed as high pressure crosses the
Great Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
UPDATE...JLA
SHORT TERM...JLA
LONG TERM...07
AVIATION...KC
MARINE...JLA
Area Forecast Discussion
National Weather Service Omaha/Valley NE
319 AM CDT SAT SEP 24 2016
.SHORT TERM...(today through Monday)
Issued at 259 AM CDT SAT SEP 24 2016
Precipitation chances will be increasing through the day with
strong and possibly severe storms affecting the area later this
afternoon through early evening.
An accas field noted on recent 11-3.9u satellite imagery was
moving through the forecast area, with radar now picking up a few
very small but potent showers in northwest/southeast oriented
band. Most recent HRRR model runs picked up on this well, with
best forcing continuing to lift northward through the forecast
area before 12z.
Meanwhile, the eastward advancing north/south band of
thundershowers across central NE and western KS oriented ahead of
an advancing cold front should make progress eastward into at
least eastern NE 12-15z, although these should not be particularly
strong. By mid morning, we may also see new development in the
warm sector across eastern KS, which may move into our southern
forecast area south of I80 15-18z. Beyond then, thunderstorms
should become more numerous through the remainder of the afternoon
as instability builds, eventually reaching 2000-2500 J/kg as
surface dewpoints peak near or in the lower 70s. Bulk shear of
30-35 knots and more unidirectional hodographs should support
multicells, with at least a marginal risk of severe storms. NSSL
WRF 4km model suggests hail in some of the strong storms could
reach 1-1.5", which may be a bit greater probability than latest
Day outlook from SPC. PW values also increase to around 2" during
the afternoon and early evening...which is 2-3 standard deviations
above normal. Thus locally heavy rainfall will be possible. Storms
should be progressive, but some areas could see 1-1.5" before all
precip comes to and by daybreak Sunday.
Much cooler and drier weather for Sunday and Monday.
.LONG TERM...(Monday night through Friday)
Issued at 259 AM CDT SAT SEP 24 2016
Dry weather through Thursday as upper ridge builds across the
Plains. Temps do warm back into the mid to upper 70s during this
time. Rain chances increase by Thursday night and Friday as the
next upper wave moves out of the central Rockies, although timing
is off between the models with GFS about a day faster than the
ECWMF.
&&
.AVIATION...(06Z TAFS for KOFK...KLNK and KOMA.)
Issued at 1152 PM CDT FRI SEP 23 2016
VFR conditions are expected tonight, with wind shear likely at all
sites through morning. Have indicated showers reaching KOFK in the
morning and KOMA/KLNK in the early afternoon, with a couple hours
of PROB30 thunder mention at each site at the best guess of
timing. Front will bring winds around to the west/northwest at
KOFK before the end of the TAF period.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...DeWald
LONG TERM...DeWald
AVIATION...Mayes
Area Forecast Discussion...UPDATED
National Weather Service Mount Holly NJ
432 AM EDT Sat Sep 24 2016
.SYNOPSIS...
A cold front will move southward through the Delmarva region
early this morning. High pressure over eastern Canada will build
southward toward the mid-Atlantic states through the weekend. The
center of the high will retreat off the East Coast Monday
afternoon. A cold front is expected to move in from the west
Monday night before pushing offshore sometime on Tuesday. An area
of low pressure may cutoff to our west midweek. High pressure
looks to eventually build back into the region late in the week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A cold frontal boundary will continue to push southward through
the region this morning. As a result, a thick overcast will
continue to build southward ahead of the front. The overcast
should slowly lift and thin out this afternoon with the front
moving well south of the region. Due to the overcast, temperatures
will struggle to rise into the low 70`s today. The NAM and HRRR
indicate enough lift for a brief light shower or two across
southeastern PA, central and southern New Jersey during the
morning hours. We have some slight chance pops across these
regions. Any rainfall will be light.
Winds will increase out of the north and northeast around 10-15 mph
with slightly higher gusts today centered in the late morning and
early afternoon hours. High pressure building toward the region
later today will actually allow winds to decrease some by days end.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
High pressure will continue to build southeastward into the region
tonight eroding away any remaining clouds. Conditions will be
favorable for radiational cooling across the region. More rural
locations should fall a few degrees below MET and MAV statistical
guidance with most of the region in the 40`s for lows. Still to
warm for any frost concerns.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
High pressure centered over Hudson Bay and along the Ontario-Quebec
border will continue to build southward into the mid-Atlantic region
on Sunday. The CAA pattern that develops behind the cold front today
will persist over the area on Sunday but start to weaken. Even with
abundant sunshine, high temperatures in the lower 70s (60s in the
higher elevations) will likely fall shy of climo but only by a
couple of degrees. Nonetheless, it will certainly feel like autumn
after the summer-like warmth that has occurred across the region
through much of September.
On Sunday night, there will be a very favorable setup for
radiational cooling with the surface ridge axis in the area. With
clear skies, calm winds, a very dry airmass in place and
increasingly longer nights this late in the year, Sunday night has
the potential to be the coolest night of the month and possibly
since late May in spots. Under this type of pattern, sided with the
colder MOS guidance, if not below it, for low temperatures. Patchy
frost may form in the sheltered valleys of northeastern PA and
northwestern NJ before sunrise early Monday.
High pressure and H8 ridge axis will shift offshore on Monday.
Southerly return flow around the high will establish a WAA pattern.
However, the WAA will be relatively weak and brief in duration,
precluding a significant warm up early next week. This is because a
progressive cold front will move through the region Monday night.
PoPs were increased to likely for Monday night into Tuesday morning
with the 00Z model runs coming into much better agreement with the
timing of the rainfall along and ahead of the front. While any
rainfall would be much welcomed, it won`t be a drought buster for
portions of eastern PA and NJ that are under a D1 drought with QPF
amounts generally around one-half inch.
There is a significant degree of forecast uncertainty for the second
half of the work week with the potential for the upper low over the
Great Lakes to become cutoff. Models are having a difficult time
handling this system, exhibiting a considerable amount of run to run
spread. For example, the latest 00Z ECMWF showed a cutoff low
forming over the Ohio Valley Wednesday night and stalls it near the
central Appalachians for several days (into next weekend). This run
gives us an extended period of wet weather. Meanwhile, the 12Z ECMWF
from yesterday showed a much more progressive solution as the low
harmlessly kicks out to sea midweek, followed by high pressure in
control late in the week and next weekend. The GFS followed the
opposite trend. Both the GEFS and ECMWF ensembles exhibit large
spread. For now, introduced slight chance PoPs Wednesday afternoon
through Thursday but did not go any higher due to the low
predictability. Temperatures should be near normal mid to late
week.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY and surrounding areas.
A MVFR stratus deck will continue building southward through the
morning hours. This deck has already reached KABE and is encroaching
upon KTTN and KRDG. Timing uncertainties of a couple of hours are
present with the arrival of MVFR ceilings, so TEMPO groups were
included to represent this in the 06Z TAFS. This deck will slowly
thin out and lift from north to south during the late morning and
afternoon hours.
North-northeasterly winds from 7-15 knots are possibile today with
any gusts in the late morning or early afternoon hours. Winds will
decrease tonight.
OUTLOOK...
Sunday through Monday...VFR. Light winds Sunday. Southerly flow
strengthens Monday with gusts to 20 kt possible during the afternoon.
Monday night and Tuesday...SHRA likely as a cold front moves in from
the west. MVFR conditions probable with the potential for IFR in
heavier/steadier rain. Gradual improvement from west to east during
the day Tuesday.
Tuesday night and Wednesday....Predominately VFR.
&&
.MARINE...
Wave heights will gradually build to around five feet on the
ocean waters by this afternoon after the passage of a cold front.
Winds will also increase from the north and northeast around 15
knots with some gusts to 25 knots possibile. A SCA is in effect
through tonight as the five foot seas may linger.
OUTLOOK...
Sunday...SCA extending into Sunday morning for the coastal Atlantic
zones. Long-period southeasterly swells from Tropical Storm Karl is
expected to continue along the coast during the morning. Seas around
5 ft are expecting in the morning before subsiding to 3-4 ft in the
afternoon.
Monday through Wednesday...No marine headlines expected. Winds may
gust out of the south to around 20 kt Monday afternoon and evening
ahead of a cold front.
Rip Currents...Both long period swells and building seas suggest
conditions may be more representative for a moderate risk of rip
currents.
A moderate risk for the formation of dangerous rip currents will
likely continue into Sunday with long-period southeasterly swells
from Tropical Storm Karl expected to impact the eastern seaboard.
&&
.CLIMATE...
The high temperature yesterday, September 23rd, at Allentown, PA
(KABE) was 90 degrees. While this did not set a daily high
temperature record, it marked the second latest 90-degree day in
the calendar year at KABE since 1970. During this span, the only
other date that reached 90 degrees this late in the year was
October 8, 2007.
Note: A high temperature of 90F on October 8, 2007 was also the
latest occurrence of a 90-degree day in a calendar year on record
for KABE. Allentown historical climate records go back to 1922.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...Small Craft Advisory until noon EDT Sunday for ANZ452>455.
Small Craft Advisory until noon EDT Sunday for ANZ450-451.
&&
$$
Synopsis...Klein
Near Term...Gaines
Short Term...Gaines
Long Term...Klein
Aviation...Gaines/Klein
Marine...Gaines/Klein
Climate...Klein
Area Forecast Discussion
National Weather Service Pueblo CO
1033 PM MDT FRI SEP 23 2016
.UPDATE...
Issued at 803 PM MDT Fri Sep 23 2016
Updated to expire red flag warning. Winds are still strong, but
humidity has increased above 15 percent most areas. Storms firing
in moist air over the plains east of the dry line, though modest
instability has kept intensity below severe levels so far. Still a
threat of a few severe wind gusts as storms fly north at 40-50
mph, with threat ending 05z-06z acording to latest HRRR.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 301 PM MDT Fri Sep 23 2016
...A variety of high impact weather to continue across southern CO...
An intense upper low over NW UT/SW WY will continue to lift
northeastward with trailing trof axis swinging across southern CO
during the evening hours...a little behind earlier model
projections. This will put the brunt of the energy crossing the
eastern mountains between 00z and 03z with strong downward forcing
coming in quickly behind. Dry line has been slow to sharpen
up...though in last hour dew point at COS plummeted from 39 to 15
degrees F...so once winds shift out of the southwest to west...it
shouldn`t be too long before rapid drying takes place. Winds have
been gusting to 40-50 mph at times and this will continue through
the evening and overall Red Flag Warning still looks on track. To
the east of the dryline...high res models are developing a broken
line of thunderstorms between 4 PM and 5 PM. Dew points in the lower
50s yield mixed layer CAPE values of 1000 J/kg in SPC meso analysis.
Deep layer shears will be running around 30-40 kts...so potential
for one or two severe thunderstorms across the eastern counties
still looks possible. Storms will be moving rapidly north
northeastward with HRRR showing most of the activity done by 06z.
Given high based nature to thunderstorms...main threat still looks
to be winds over 60 mph and hail to around 1 inch in diameter.
As the upper low lifts northeastward should see activity tail off
from west to east...though northern portions of the Continental
Divide may continue to see off and on snow showers through the
overnight hours. Cold front moves in overnight...and a widespread
freeze still looks likely for the San Luis Valley. Have upgraded the
freeze watch to a freeze warning. Temperatures will be cooler
elsewhere...but winds should keep temperatures from dropping too
close to the freezing mark.
Saturday will be cooler behind the front...though secondary push of
cooler air will approach the Palmer Divide during the afternoon.
Just enough moisture will be present along the CONTDVD and northern
portions of the southeast mountains for some isolated to scattered
showers and thunderstorms to redevelop...but overall...any
precipitation looks light at this point. -KT
.LONG TERM...(Saturday night through Friday)
Issued at 301 PM MDT Fri Sep 23 2016
...Feeling more like Fall on Sunday...
The global models have come into better agreement today. The
strong upper low moving through W CO today will split this
weekend, with most of the energy lifting off to the NE. The base
of the trough will cut off over W NM, then slowly eject to the NE
during the mid to latter portion of the coming week.
Sat night...the main low will be well north of our area...over
the Nrn High Plains, while the trough axis is moving through E CO
and the base of the trough beginning to split and cut off over NM.
This will be the coldest air mass of the extended, with H7 temps
getting down to around zero degrees over Teller County by early
Sun morning. So...there could be a few snow showers above 9000
feet early Sunday, and possibly some light localized accums...but
significant or widespread snow appears unlikely, and the latest
model trends are for less QPF over the area.
Main impact from this system will be considerably cooler wx on
Sunday, with high temps only in the 60s for the Plains and 40s
for the mts. WIll clear out pretty quickly Sun morning-afternoon,
leaving our area with building high pressure from the west, which
will keep us dry through at least Tuesday. Temps will gradually
increase during this time period.
By early Wednesday, the cut-off low to our south will finally
begin moving into SW CO. This system will be much weaker than the
current upper low, and with the Southwesterly trajectory, will
also be quite a bit warmer aloft. So, snow levels will likely stay
pretty high for the last week in September, generally above 12000
feet. Showers will be on the increase, especially for the latter
part of Wed into early Thu. Have left mention of TS in the grids
for this period since there will be some modest instability with
the upper low. But for the balance of the forecast period,
climatology does not favor widespread TS, so left any precip as
Showers for the rest of this period.
Once the second upper low moves through from the SW, our area will
likely stay in an unsettled pattern with shortwaves moving through
the Central Rockies. Current forecast assumes southwest flow over
the CWA, so temps will remain generally above average. Rose
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1030 PM MDT Fri Sep 23 2016
Gusty winds will continue to diminish in the wake of a front
which passed through the region this evening with VFR conditions
anticipated over the KALS...KCOS and KPUB TAF sites into Saturday
night.
&&
.PUB Watches/Warnings/Advisories...
Freeze Warning until 9 AM MDT Saturday for COZ069>071.
&&
$$
Area Forecast Discussion
National Weather Service SAN ANGELO TX
1143 PM CDT FRI SEP 23 2016
.AVIATION...
/06Z TAFS/
VFR conditions persist late this evening. MVFR low clouds can be
seen south of our TAF sites in satellite imagery beginning to
form and move northwest into our area. Going off of current
trends, have delayed the onset of low clouds an hour or two from
the previous forecast. Still expecting these clouds to linger
through most of the morning before lifting to VFR heights for the
afternoon hours. Showers and thunderstorms are expected to begin
affecting the area sometime during the afternoon, so may have to
introduce at least a VCTS for area sites from the afternoon into
the evening hours. 20
&&
.PREV DISCUSSION... /issued 637 PM CDT FRI SEP 23 2016/
AVIATION...
/00Z TAFS/
Current VFR conditions will deteriorate to MVFR after midnight
tonight with most locations settling between 1500 and 2000 feet.
Expect the MVFR CIGs to persist through most of the morning
Saturday before lifting to VFR by around 18Z. Winds will be light
and southeasterly tonight, becoming more southerly around 12 knots
tomorrow afternoon with gusts to around 20 knots. 20
PREV DISCUSSION... /issued 349 PM CDT FRI SEP 23 2016/
SHORT TERM...
(Tonight and Saturday)
The primary heavy rainfall event starts to occur Saturday Night, so
the long term part of the discussion will deal with those concerns.
For tonight, visible satellite shows some agitated cu across much of
West Central Texas, but the latest HRRR is showing only a few
isolated showers and storms developing this evening. This pretty
well covered in the current forecasts so left that part of it alone.
Convection will likely develop tonight to the west across the South
Plains and Permian Basin as lift ahead of the large upper level
trough axis begins to move into West Texas. These storms should
slide east and increase in coverage Saturday afternoon. Have
increased rain chances across the northwest Big Country, mainly
north of a Sweetwater to Throckmorton line for Saturday afternoon.
Areas farther south will wait for Saturday Night and beyond for
their best chances.
As for temperatures, mild again tonight as low clouds develop across
much of the area by morning. Increasing cloud cover during the day
on Saturday will begin to cut into afternoon highs. Still, enough
sunshine in the afternoon for upper 80s and lower 90s, the hottest
day we will likely see for the next week.
07
LONG TERM...
(Saturday Night through next Friday)
The main focus is with the likelihood of heavy rainfall and the
threat for flooding this weekend into Monday.
By Saturday evening, an upper low is forecast to be over the
Montana/ North Dakota border, with an upper trough extending south
across western New Mexico. The GFS and ECMWF are in better agreement
with the development of a closed low over southwestern New Mexico
Saturday night. This low is progged to drop slowly south-southwest
into Mexico on Sunday, and then retrograde slowly Sunday night into
northwestern Mexico by Monday evening. With the northern part of the
aforementioned trough progged to move east across the northern
Plains on Sunday, trailing portion of a cold front is progged to
move south into our northern counties Sunday afternoon, and then
to make slow progress south through the rest of our area Sunday
night and early Monday morning.
Abundant moisture will be in place with precipitable water values
1.5 to 2 inches across our area, with low-level moisture influx from
the Gulf of Mexico, and mid-high level moisture incorporated into
the system from the eastern Pacific.
In the Saturday night to Monday time frame, several disturbances
aloft are progged to rotate around the eastern periphery of the
upper low and into the western half of Texas. With this setup,
anticipate several rounds of showers and thunderstorms with
increased coverage and heavy rainfall. In addition, the slow-
moving frontal boundary will provide an additional focus for heavy
rain. Rain chances will ramp up Saturday night and continue
through Sunday night, with likely PoPs extending through Monday.
From Saturday night through Monday, widespread rainfall totals of
2-4 inches will be likely, with locally higher amounts possible.
While our area can take some rain initially, expect multiple rounds
of convection to saturate the ground and lead to excessive runoff/
flooding. A flash flood threat will also exist. We are monitoring
this developing wet weather situation closely, and a Flash Flood
Watch may be issued if the next set of models continue to show this
setup for our area.
Temperatures will be much cooler at the beginning of the week,
especially on Monday. Rain chances will be lower, but still present
in parts of our area Tuesday and Wednesday. Later in the week,
temperatures are expected to warm back into the lower to mid 80s for
highs (Thursday and Friday), when an upper level ridge tries to
build back into our area.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 71 88 69 77 / 20 50 70 80
San Angelo 73 92 71 78 / 10 40 70 80
Junction 73 91 72 82 / 20 30 60 70
Brownwood 71 89 71 80 / 20 40 50 80
Sweetwater 69 88 69 73 / 20 60 80 90
Ozona 72 89 70 78 / 10 40 70 80
&&
.SJT Watches/Warnings/Advisories...
None.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
304 AM CDT SAT SEP 24 2016
.SHORT TERM...(Today and tonight)
Issued at 302 AM CDT Sat Sep 24 2016
Upper low over CO/WY at this hour pushing a piece of energy
northeast in to Nebraska and western Kansas has generated a broken
line of showers and embedded thunder over the western parts of the
state. Some of these may reach western counties toward sunrise. As
the low approaches, precipitation patterns in the guidance indicate
several rounds of enhanced rain chances. Stronger impulse progged
to lift NE out of central Oklahoma and bring another increase in
coverage for the afternoon hours. This may act in concert with an
increase in instability to bring a strong storm to the area in the
afternoon hours. NAM / HRRR are more generous with the instability
while GFS and RAP less so. As of the early morning hours of
Saturday, area remains in a marginal risk for severe storms with
primary concerns for wind gusts and locally heavy rain. Highs today
forecast in the low to middle 80s.
PW values from last evenings sounding near an inch climb to near 1.5
inches by this morning, and toward 2 inches by Saturday evening as
moisture plume streams northward ahead of the upper low, and initial
stronger storm development could bring some training storms and
locally heavy rainfall. As front moves in for the overnight hours
Saturday night, this plume pivots over the eastern counties and
brings the locally heavy rain threat east as it does so. Total
forecast amounts are generally 2 inches or less, but would
anticipate some locally higher amounts as storms train from SW to NE
along the front as it slowly pushes SE. On the downside will be
decreasing instability which could help diminish precip efficiency.
Overnight lows with clouds and rain look to hold in the upper 50s
far northwest to middle 60s southeast.
.LONG TERM...(Sunday through Friday)
Issued at 302 AM CDT Sat Sep 24 2016
By Sunday morning the cold front will bisect the forecast area as it
continues to progress southeastward. At this time the northern
stream trough will be tracking over ND with the one axis extending
southward over central KS. A few of the models are showing an
increase in mid level frontogenesis at this time as well as energy
lifting out of the southern stream, which may enhance the precip
across the southeast half of the forecast area during the morning.
The NAM is most aggressive with this scenario therefore will have
watch the latest trends to see if the artifact is real, and if so
where it may come together. With the possibility of enhanced precip
rates an additional 0.5 to 1 inch of rainfall may be possible, but
confined to east central KS. This area will have to be monitored for
potential flash flooding, which will depend of how much rain falls
late Saturday and overnight. By mid day though the front should exit
the area and most locations will be drying out. North central KS
will pretty much remain dry after sunrise Sunday. In the evening
another mid level trough axis will swing out over the plains forcing
the moisture and lift southward. The Canadian air mass will quickly
move in behind the front supported by a surface high pressure, which
is forecasted to track through the high plains. The coolest low
temperatures will be on Monday and Tuesday mornings with mid to
upper 40s for most locations. While high temperatures stay in the
70s through Friday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1159 PM CDT Fri Sep 23 2016
VFR conditions are likely for the majority of the TAF period with
the exception being any periods of thunderstorms when vis would be
reduced and locally strong wind gusts will be possible. One round
of storms may impact MHK after 13Z with a lesser chance to reach
as far east as FOE/TOP by 15Z. Better chances for storms are after
20Z and occasional storms may continue through the remainder of
the TAF period.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...67
LONG TERM...Sanders
AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Bismarck ND
943 AM CDT Sat Sep 24 2016
.UPDATE...
Issued at 943 AM CDT Sat Sep 24 2016
Made a few adjustments with the update to extend fog across the
west and north. Based on web cams and some obs, it is eroding at
some locations but slower than expected. HRRR tries to hold onto
fog into early afternoon across the west. Also expanded low pops
across parts of south central ND with some showers continuing to
move through the area.
No changes with latest SPC day 1 outlook with a marginal risk
covering portions of our east. There will be a window of
opportunity during the afternoon for some strong storms. NAM
continues to be more aggressive with instability, showing up to
2500 J/KG of CAPE mid afternoon from James River Valley through
northcentral ND, with GFS not quite as unstable. Latest HRRR
however does not show much convection across our east.
UPDATE Issued at 655 AM CDT Sat Sep 24 2016
Did an update to pops and sky cover to account for convection
passing just west of the Mandan / Bismarck area. Otherwise no
changes to the inherited forecast.
&&
.SHORT TERM...(Today and tonight)
Issued at 450 AM CDT Sat Sep 24 2016
The mid level low was on the forecast track of the NAM and it was
followed more closely this forecast cycle. Temperatures today
will have a wide range from the cloudy, showery Divide County to
where the sun breaks out in Logan County.
Mid level low was moving through Wyoming this morning toward North
Dakota with its surface feature out ahead. As the circulation
approached, showers were moving more northwest, caught in the
circulation. With no returns upstream and the short term hi res
HRRR showing no showers for much of the morning, have dropped pops
all but the west and north. The central part of the forecast area
breaks into some sunshine this afternoon in the dry slot. CAPE and
instability increase in warm air advection and support
thunderstorm development in central North Dakota. As the storms
move northeast they`ll encounter increasingly unstable air and sub
severe hail and wind will become a concern. Any severe weather
should be very limited in the Bismarck NWS forecast area and
confined to low end severe if it reaches that level at all.
Concern for tonight is the next short wave moving through the
circulation with another round of showers, maybe a rumble of
thunder. As the surface low moves through the wind shifts and
increases. Bufkit soundings for southwest North Dakota show steady
30 to gusts 45 mph of wind will reach the surface. There is
higher wind than that aloft and it is possible this could mix
down to the higher terrain southwest. For now will go with
advisory for winds 30 to 45 mph and keep the high wind warnings
in our toolbox until we see the whites of its eyes. Any showers
will act to mix that higher wind to the surface so we`ll have to
monitor closely.
.LONG TERM...(Sunday through Friday)
Issued at 450 AM CDT Sat Sep 24 2016
Showers taper off west early Sunday as the cyclone pulls away and
becomes an open wave, but the wind will be left behind. Have
continued the wind advisory for the southwest through Sunday but
wouldn`t be surprised if the Sunday day shift can cancel it a bit
early. Generally cooler and windy to very windy Sunday, but with
increasing sunshine from the west.
After that an H5 ridge builds over the area and much of the coming
work week is dry and mild with lows in the 40s and highs 65 to 75.
The coolest night starts the period, Sunday night-Monday morning,
with a lot of places dipping into the upper 30s.
The next rain producer looks to come in late in the week and into
next weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday night)
Issued at 655 AM CDT Sat Sep 24 2016
Widespread IFR/LIFR conditions in stratus and fog will continue
across many parts western and central North Dakota through
Saturday morning. Conditions will improved to MVFR to VFR mid-day.
A cold front will move through overnight with gusty winds in its
wake, with a reduction in cigs to IFR/MVFR possible.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 5 PM this afternoon to 5 PM MDT Sunday for
NDZ040-041-043-044.
&&
$$
UPDATE...JNS
SHORT TERM...JPM
LONG TERM...JPM
AVIATION...JJS
Area Forecast Discussion
National Weather Service Lincoln IL
1045 AM CDT SAT SEP 24 2016
.UPDATE...
Issued at 1040 AM CDT Sat Sep 24 2016
Most of the fog lifted across central IL by 10 am and did an
update to the forecast at that time to remove the morning fog
working. Still have lingering stratus clouds below 1k ft along and
north of a Canton to Bloomington/Normal line, but that shallow
cloud layer is starting to dissipate too and should scattered
out by noon. Scattered cumulus clouds should develop by afternoon
across much of CWA with mostly sunny skies overall prevailing.
Another very warm summerlike day expected over central and
southeast IL, with highs ranging from mid 80s from I-74 northeast
to the upper 80s to around 90F sw of I-74.
Latest surface map shows 1029 mb high pressure over central
Ontario province and ridging southward into the Great Lakes and
Ohio river valley. 1005 mb low pressure was along the western
SD/ND border, with IL inbetween these two features. A weak frontal
boundary extended from near Quincy to Taylorville to Robinson.
Models show this frontal boundary lifting back north during the
afternoon especially across western half of IL as weak ENE winds
less than 10 mph veer more southerly. This to keep rather muggy
conditions around with dewpoints of 65-70F. Hi-res models are
keeping much of CWA dry through this evening as strong upper
level ridge (591 dm 500 mb high over mid MS river valley) hold
over IL. HRRR and RAP models do show very isolated convection
along the frontal boundary from mid afternoon into early evening
over IL river valley in nw CWA, but like yesterday feel the upper
level ridge will be strong enough to suppress this convection,
plus forcing/lift along front is quite weak.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 325 AM CDT Sat Sep 24 2016
A weak boundary will located from west central IL into southeast IL
this morning. Most of the CWA is north of this boundary where winds
are primarily out of the east-northeast. Patchy fog has developed
north of this boundary over a good portion of the CWA, as well as in
southeast IL. In addition, stratus is spreading west into northern
parts of the CWA and is forecast to ooze south some early this
morning. Do not expect this area of clouds to remain the whole day,
but could take several hours before it dissipates/burns off/lifts
north out of the CWA. So will have to have some mostly cloudy skies
in the north and northeast this morning, then becoming partly sunny
this afternoon. Temps will be a little cooler as well, probably only
reaching into the lower 80s by this afternoon. Other areas of the
CWA where there will be much more sunshine will see afternoon
highs reaching the mid to upper 80s, and around 90 in some areas.
Late tonight there should be an influx of more moisture and clouds
into the CWA as the next weather system approaches the area. Trend
in the models is for a little slower timing of the onset of precip.
So, any chance of precip will be very late tonight, well after
midnight. Clouds will keep temps up some, but still expecting mid to
upper 60s for overnight lows. In addition, patchy fog should be an
issue across the CWA late tonight.
.LONG TERM...(Sunday through Friday)
ISSUED AT 325 AM CDT Sat Sep 24 2016
Only real precipitation issue in the longer range will be the timing
of the front Sunday afternoon and evening. Most of the model
guidance has it roughly along the I-55 corridor by around 7 pm and
exiting the forecast area toward midnight. While an isolated severe
storm can`t be ruled out, both the GFS and NAM are indicating very
weak bulk shear values where the higher CAPE`s are progged, although
the GFS has the higher CAPE`s more along the front near the edge of
where the shear increases. By evening, the instability quickly
wanes, and any thunderstorms will mainly be east of I-55 and during
the early evening. A few storms may linger past midnight east of I-
57, though.
Welcome shot of more fall-like weather is on tap early next week, as
upper low currently over southwest Wyoming lifts northeast and
reforms near the Minnesota/Ontario border. As the low drifts north
of the Great Lakes, it will draw down a slug of cooler air into the
Midwest, with 850 mb temperatures as low as 3C over central Illinois
by late Monday evening. Temperatures Monday night and Tuesday night
likely to dip into the upper 40s, with daytime highs Monday-Tuesday
in the upper 60s to lower 70s. The strength of the low will also
result in fairly windy conditions on Monday, with Bufkit guidance
indicating some potential for 25-30 mph gusts across the northern
CWA.
The upper low will be a bit slow to depart, with the latest ECMWF
gradually sinking it into the eastern Tennessee Valley late in the
week. That solution would result in a more extended period of cooler
conditions most of the week. This is a fairly substantial change
from the previous run, which was much closer to the evening GFS
solution that builds modest ridging eastward late in the week.
Thus, will follow more of a blend of the current GFS and yesterday
morning`s ECMWF, indicating a gradual warming trend toward the
upper 70s late next week.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 646 AM CDT Sat Sep 24 2016
IFR cig/vis category or worse is present at all sites this
morning. Fog and low stratus present but should begin to dissipate
in next couple of hours at most sites. Timing of this
clearing/dissipation is based on model consensus for this
morning. CU will also develop later this morning but then
dissipate early this evening after loss of heating. Various models
and satellite simulations indicate that fog will occur again at
all sites. Unsure as to exact timing and how low it will get, so
will just show trend of reducing vis into MVFR category around
midnight. Winds through the period will be mainly east to
southeast.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...07
SHORT TERM...Auten
LONG TERM...Geelhart
AVIATION...Auten
Area Forecast Discussion
National Weather Service Melbourne FL
945 AM EDT SAT SEP 24 2016
.DISCUSSION...
...Long period swells will bring an increased risk for strong rip
currents to the local beaches through the weekend...
Current...The weak/broad surface trough that had been over the area
for the past several days has dissipated. The SLP pattern remains
week/baggy across Florida with about a 1 to 1.5MB pressure gradient
from north Florida to the Keys. Visible satellite shows sunny to
mostly sunny skies across the peninsula save for some CI/CS debris
clouds across the southern third to half of the peninsula. Water
vapor imagery and RAP analysis fields show a H30-H20 low centered
over the eastern FL panhandle, extending from SE Alabama/SW Georgia
southward across the eastern GOMEX and the adjacent western FL
peninsula. The low has a W-E elongated reflection at H50.
Morning RAOBs continue to show a decent moisture gradient in place
over the peninsula with 1.55-1.65" PWATs at JAX/TBW and around 2.0"
at XMR/MFL. deep layer flow remains SW, generally light from just
off the deck up to H50, but a little stronger and more backed above
that level, owing to the aforementioned upper low.
Rest of today...Setup looks quite similar to Friday with combination
of deep moisture and weak surface and steering winds. In fact, the
low aloft actually looks like it may be a little more favorably
divergent today. Current POP forecast ranging from 30 north to 50
south looks fine. Am a little inclined to nudge the numbers up by 10
percent across the southern CWA again, but the current forecast is
in decent agreement with surrounding CWAs, so may leave it as is.
Beachgoers are advised that long period swells (3-5 ft/11-12 sec),
emanating from recurving TC Karl, will increase the risk for
dangerous/strong rip currents at the east central Florida beaches
this weekend. Check with your local beach patrol for ocean hazards.
&&
.AVIATION...VFR with some late morning high end MVFR CIGS BKN020-030
developing with diurnal CU field starting ~15Z. MVFR-IFR in SHRA/TS
expected once again by 17Z-18Z, with best chance along the MLB-SUA
corridor through 21Z, shifting toward the inland aerodromes 22Z-02Z.
&&
.MARINE...Another day of minimal wind/chop with a dominant 11-12s
period swell from TS Karl. Local buoys indicate swells of 2-3FT near
the coast and 3-4FT farther offshore, which is right in line with
the current forecast. Both the NWPS and WNAWAVE guidance suggest an
increase in seas of about 1FT late tonight before waning on Sunday,
as Karl accelerates NE across the north Atlantic. No changes to the
grids/CWF.
&&
UPDATE...Cristaldi
RADAR/IMPACT WX/AVIATION...Spratt
&&
.PREV DISCUSSION... /issued 345 AM EDT Sat Sep 24 2016/
Winds will again become L/V this evening/overnight. Highs today will
stay persistent with U80s to near 90 degrees along the east coast
and L90s into the interior. Overnight lows keeping in the L-M70s.
Sunday...Moisture profiles will remain similar to recent days with
deepest moisture lingering from Okeechobee county to the Treasure
coast with PWATs from 1.8-1.9 inches. Aloft a mid/upper level low
will elongate near the FL panhandle with light WSW-SW winds at h5
and light southerly flow aloft. Sfc high well north of the area will
allow low level flow to turn onshore albeit fairly light. Will fcst
40-50 pops far srn areas and 30-40 pct across the nrn CWA. Highs
upper 80s coast to around 90 across the interior. Long period swells
from Karl will keep the rip current risk elevated at east central FL
beaches.
Monday...Light onshore flow will veer to the east-southeast in the
afternoon with models progging lower PWATs from Orlando northward
around 1.6 inches and deeper moisture across srn sections once
again. Will keep POPs around 40 percent northern sections mainly
with scattered convection developing in the mid to late afternoon.
Rain chances in the 40-50 percent range across srn sections where
some convection may begin by early afternoon with deeper moisture
present. Highs upper 80s coastal to around 90 for the interior.
Tue-Wed...Low level flow will continue to veer to SW Tuesday and WSW-
W on Wed ahead of an approaching frontal boundary which will move
toward N Fl Tue aftn and the nrn peninsula by Wed evening.
Increasing moisture levels ahead of the front will support mainly
diurnal scattered showers and storms that will last into evening
each day. Will keep POPs in the 40-50 percent range for now.
Thu-Sat...00Z models begin to diverge for late week forecast with
00z GFS latching closer to yesterday`s more progressive ECM solution
which portends sfc high pressure quickly bridging the front late
week turning low lvl flow onshore by Thu afternoon into weekend with
increasing moisture and scattered to numerous Atlantic showers (and
isolated lightning storms) moving onshore to start next weekend.
Will follow closer to GFS solution at this point which is supported
by WPC preference with 00Z ECM looking like an outlier from recent
other global model runs. Will keep rain chances in the scattered
range Thu-Fri and advertise slightly higher POPs by Saturday with
GFS indicate deep moisture entrenched and stronger onshore low level
flow as pressure gradient tightens some. This type of pattern can be
supportive for coastal heavy rain events for ECFL...though since
this is out at Day 6-7 still have plenty of time to refine any
potential for locally heavy rain next weekend.
&&
.AVIATION...Mainly VFR outside of afternoon/evening convection.
ISOLD-SCT showers/storms will be the main focus again this
afternoon/evening as the ECSB forms and pushes slowly inland. Higher
deep layer moisture continues across the Space/Treasure coasts.
Tempo MVFR with showers/storms, especially south of KMCO.
&&
.MARINE...Today-Tonight...A general light offshore flow early today
will become light onshore this afternoon surrounding ECSB
development and push inland. A light offshore flow will develop
again later this evening/overnight.
TC Karl will re-curve away from the area, sending a small-moderate
easterly long period swell (11 seconds) into the local waters. Seas
generally building to 3-4FT near shore and 4-5FT offshore north of
Sebastian Inlet.
Showers and storm coverage will be isolated to scattered with a few
of these cells potentially moving off of the east coast this
afternoon/evening, especially south from Melbourne.
Sunday...NE-E winds 5-10 knots expected with an east swell to 3-4 ft
near shore and 4-5 ft well offshore. Scattered showers and storms
expected mainly across the waters south of Cocoa Beach.
Mon-Wed...East winds Monday will veer to SE tuesday and SW-S Wed.
Swells from Karl will diminish with seas dropping back to 2 ft near
the coast and 2-3 ft offshore.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 88 72 88 72 / 30 20 30 20
MCO 91 73 91 73 / 30 20 40 20
MLB 89 73 89 74 / 30 40 30 30
VRB 88 73 87 72 / 40 40 40 40
LEE 92 73 91 73 / 30 20 40 20
SFB 91 73 91 73 / 30 20 30 20
ORL 92 75 91 74 / 30 20 40 20
FPR 88 72 88 72 / 40 40 40 40
&&
.MLB Watches/Warnings/Advisories...
FL...None.
AM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
704 AM EDT SAT SEP 24 2016
.UPDATE...
Issued at 557 AM EDT SAT SEP 24 2016
Showers over western Lk Superior getting a bit too organized to just
have slight chance pops over western cwa this morning. Blend of HRRR
and ESRL HRRR and RAP suggest showers continue east where h7-h5 RH
is maximized and on edge of stronger h85 warm air advection. Showers
then slide ene across the Keweenaw Peninsula rest of this morning.
Now even some potential for rain as far east as north central Upper
Michigan this morning. Main change for now was to increase pops
across Keweenaw to likely. Just looking at a few hundredths of rain
but certainly enough to get the ground wet. Placed chance pops over
rest of western cwa next few hours and based on radar trends did
bring slight chances to the ncntrl before they lift out across Lk
Superior. No change to slight chances along WI border. Tweaked temps
down through the morning with the higher rain chances and thicker
cloud cover. Still expect skies to try to clear some possibly by
early aftn over the west half.
&&
.SHORT TERM...(Today and tonight)
Issued at 349 AM EDT SAT SEP 24 2016
Sharp upper level confluent northwest flow is present aloft over the
Great Lakes this morning between sharp ridge over central Conus and
broad trough over eastern Canada. Warm and moist air ahead of strong
Upper low over CO/WY is driving clusters of shra and tsra from
western KS and Neb and also over the western Dakaotas into southern
Manitoba where h85 warm air advection is strongest. The confluent
flow is resulting in large area of sfc high pressure from northern
Manitoba to the Upper Great Lakes. Even with the sfc high nearby,
mid and high clouds are increasing in the warm air advection pattern
aloft. Enough moistening/isentropic ascent on the 305k sfc /800-
750mb/ from northern MN to far western Upper Michigan and northern
WI to support light echoes on the regional radar and multiple obs
are showing light rain is indeed occurring under some of these
echoes. Strongest h85 temp advection remains northwest of Lk
Superior today so once the isentropic ascent and mid level moisture
begins to wane expect the sprinkles or light showers to do the same.
Have small pops over west/southwest through 14-15z then have it dry
the rest of the day with minimal additional forcing and mid levels
drying out. Mostly cloudy this morning but could see filtered
sunshine this aftn. H85 temps bounce up over 10C over the west
though looks like we will only mix to 900-875mb. Overall expect
highs in the mid-upper 60s but could see low 70s over the west.
Center of sfc high slowly moves east tonight as low pressure system
in the plains this morning /tied to the upper low/ lifts toward
southern Manitoba by daybreak on Sun while occluded front crosses
northern MN. Upper level ridge axis remains over Upper Michigan most
of the night while upper trough crosses the Dakotas. A lot of dry
air around in low levels so think the interior central and east
could see temps into the 40s inland where winds try to decouple. 50s
elsewhere as clouds increase and as southeast to south winds stay up
ahead of the front. Forecast soundings did not look promising for
any rain to reach far west by 12z Sun. However, when looking at
where the shra/tsra are occuring this morning on edge of higher h7-
h5 RH/higher pwat and fact this gradient of moisture will be pushing
over far west cwa 09z-12z tonight did bring chance pops to the far
west at that time. SI/s also nearing 0c so retained slight chance of
tsra. A lot of tsra is occurring this morning on the moisture
gradient so feel good about having at least a small mention in there
late tonight. Over most of the rest of the cwa though it should stay
dry though at least 12z with the lingering ridging aloft and dry low-
levels.
.LONG TERM...(Sunday through Friday)
Issued at 317 AM EDT SAT SEP 24 2016
Nam has a trough in the northern and central plains 12z Sun with a
shortwave ridge over the upper Great Lakes and ridging in the
western U.S. The trough moves east into the upper Great Lakes Sun
night into Mon and then moves into the lower Great Lakes Mon night.
Deeper moisture and 850-500 mb q-vector convergence arrive on Sun
and last through Sun night with Mon having the wraparound part of
system affecting the area. Did not make too many changes to the
going forecast and have likely pops overspreading the cwa Sun into
Sun night and then chance pops on Mon with wraparound part of storm
coming through.
In the extended, GFS and ECMWF are showing much better agreement at
96 hours with both having a closed 500 mb low east of Lake Superior
in Ontario 12z Tue and ridging into the Rockies and southern plains.
By 12z Wed, the trough is over the lower Great Lakes and the ridge
is into the Plains. The 500 mb ridge then builds into the upper
Great Lakes 12z Thu into Fri. Confidence is now a bit higher due to
better agreement between the GFS and ECMWF now. Temperatures look to
be above normal for this forecast period. Also looks a bit drier now
starting Wed afternoon through Friday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 702 AM EDT SAT SEP 24 2016
A few showers are expected at KCMX this morning. Otherwise, should
see scattered to broken VFR clouds today and tonight. Next chance of
rain arrives late tonight at IWD as low pressure system and frontal
boundary approach from the west. Conditions should drop to MVFR
at all the TAF sites on Sun as rain spreads over Upper Michigan.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 349 AM EDT SAT SEP 24 2016
East to southeast winds less than 20 kts today, then southeast winds
increase Tonight into Sun as high pressure moves toward Quebec and
New England and a low pressure system lifts across Mantioba to
northern Ontario. Winds may gust as high as 30 kts Sun into Sun
evening over north central and eastern sections of Lk Superior. The
low will move east of the region Mon into Tue and a cold front will
cross Lk Superior. Winds shifting to the west-northwest will
increase to 20-25 kts on Mon and could reach 30 kts Mon afternoon
into Mon night. Northwest winds to 25 kts continue on Tue then winds
diminish to 20 kts or less by Wed as high pressure crosses the
Great Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
UPDATE...JLA
SHORT TERM...JLA
LONG TERM...07
AVIATION...JLA
MARINE...JLA
Area Forecast Discussion
National Weather Service Omaha/Valley NE
654 AM CDT SAT SEP 24 2016
.SHORT TERM...(today through Monday)
Issued at 259 AM CDT SAT SEP 24 2016
Precipitation chances will be increasing through the day with
strong and possibly severe storms affecting the area later this
afternoon through early evening.
An accas field noted on recent 11-3.9u satellite imagery was
moving through the forecast area, with radar now picking up a few
very small but potent showers in northwest/southeast oriented
band. Most recent HRRR model runs picked up on this well, with
best forcing continuing to lift northward through the forecast
area before 12z.
Meanwhile, the eastward advancing north/south band of
thundershowers across central NE and western KS oriented ahead of
an advancing cold front should make progress eastward into at
least eastern NE 12-15z, although these should not be particularly
strong. By mid morning, we may also see new development in the
warm sector across eastern KS, which may move into our southern
forecast area south of I80 15-18z. Beyond then, thunderstorms
should become more numerous through the remainder of the afternoon
as instability builds, eventually reaching 2000-2500 J/kg as
surface dewpoints peak near or in the lower 70s. Bulk shear of
30-35 knots and more unidirectional hodographs should support
multicells, with at least a marginal risk of severe storms. NSSL
WRF 4km model suggests hail in some of the strong storms could
reach 1-1.5", which may be a bit greater probability than latest
Day outlook from SPC. PW values also increase to around 2" during
the afternoon and early evening...which is 2-3 standard deviations
above normal. Thus locally heavy rainfall will be possible. Storms
should be progressive, but some areas could see 1-1.5" before all
precip comes to and by daybreak Sunday.
Much cooler and drier weather for Sunday and Monday.
.LONG TERM...(Monday night through Friday)
Issued at 259 AM CDT SAT SEP 24 2016
Dry weather through Thursday as upper ridge builds across the
Plains. Temps do warm back into the mid to upper 70s during this
time. Rain chances increase by Thursday night and Friday as the
next upper wave moves out of the central Rockies, although timing
is off between the models with GFS about a day faster than the
ECWMF.
&&
.AVIATION...(12Z TAFS for KOFK...KLNK and KOMA.)
Issued at 642 AM CDT SAT SEP 24 2016
An upper level storm system over Wyoming will track toward Canada
through tonight with a warm...moist...and unstable airmass ahead
of the cold front. Multiple rounds of showers and thunderstorms
are expected today. Generally vfr conditions...however mvfr
conditions will be possible with heavier precipitation. Rain
chances will decrease at KOFK after 21z and KOMA and KLNK after
03z.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...DeWald
LONG TERM...DeWald
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Tallahassee FL
958 AM EDT SAT SEP 24 2016
.NEAR TERM [Through Today]...
The 8 am EDT regional surface analysis showed a broad area of
higher pressure across much of the Southeast. There were a few
thunderstorms across our coastal waters, focused mainly along the
nocturnal land breezes, but these were diminishing. Vapor imagery
and upper air data showed a strong ridge from the central Gulf
Coast to the upper Midwest, but there was a weak minimum in the
height/temperature fields centered over Tallahassee. The latest
RAP analysis did not show any Q-G forcing associated with this
low. The air above 700 mb was very dry across our region, and it
will be difficult to get much in the way of deep moist convection
this afternoon. The best chance of getting any convection is along
the coast around Apalachicola, where sufficient PBL moisture and
sea breeze convergence will coincide. Our early morning forecast
package reflects this thinking, with a 30% PoP in this area, and
only 20% or less elsewhere.
&&
.PREV DISCUSSION [655 AM EDT]...
.SHORT TERM [Tonight Through Monday]...
An upper level low positioned across the western part of the CWA
slides slightly west on Sunday but eventually shifts eastward on
Monday as a cold front sinks into the southeast. As the winds
shift to the east on Sunday will see an increase in moisture and
PoPs (30-50%) with a slightly more active day in terms of
coverage on Monday ahead of the cold front.
High temperatures Sunday will remain above normal with highs in
the upper 80s to lower 90s. With slightly more clouds on Monday
and more precip coverage, highs will mainly be in the upper 80s to
90.
.LONG TERM [Monday Night Through Saturday]...
A weakening cold front is forecast to move into the CWA Monday
night. Models slowly push the front through most of the CWA by
Wednesday/Thursday, however it may not clear the CWA. While drier
air with dewpoints in the 50s will move into the northwest part
of the CWA, these lower dewpoints aren`t expected to push into
the TLH area. Main impact from the front in the long term will be
temperatures returning to more seasonable values (upper 80s).
.AVIATION [Through 12Z Sunday]...
Brief reduction in vsby is occurring around TLH this morning, with
MVFR to IFR conditions currently being observed. Expect
improvements to VFR conditions within the next few hours.
Otherwise, VFR conditions are expected through the period at all
TAF sites, with only slight chances for isolated SHRA and TSRA
this afternoon.
.MARINE...
Winds will be light (less than 10 knots) and variable through mid
week with seas around one foot.
.FIRE WEATHER...
Relative humidities will remain well above critical fire weather
thresholds with light winds across the Tri-State Region.
.HYDROLOGY...
While rain is expected over the next few days, significant
rainfall amounts are not expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 95 73 91 72 89 / 20 10 40 20 50
Panama City 94 76 88 74 86 / 20 10 40 20 40
Dothan 95 71 91 70 90 / 10 10 40 20 40
Albany 94 71 91 70 90 / 10 10 30 20 40
Valdosta 93 71 89 70 88 / 20 10 50 30 50
Cross City 92 72 90 71 88 / 20 20 40 30 40
Apalachicola 91 75 87 74 85 / 20 10 20 20 40
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Fournier
SHORT TERM...Fieux
LONG TERM...Fieux
AVIATION...Pullin
MARINE...Fieux
FIRE WEATHER...Pullin
HYDROLOGY...Fieux
...Update to aviation forecast discussion...
.SHORT TERM...(Today and tonight)
Issued at 302 AM CDT Sat Sep 24 2016
Upper low over CO/WY at this hour pushing a piece of energy
northeast in to Nebraska and western Kansas has generated a broken
line of showers and embedded thunder over the western parts of the
state. Some of these may reach western counties toward sunrise. As
the low approaches, precipitation patterns in the guidance indicate
several rounds of enhanced rain chances. Stronger impulse progged
to lift NE out of central Oklahoma and bring another increase in
coverage for the afternoon hours. This may act in concert with an
increase in instability to bring a strong storm to the area in the
afternoon hours. NAM / HRRR are more generous with the instability
while GFS and RAP less so. As of the early morning hours of
Saturday, area remains in a marginal risk for severe storms with
primary concerns for wind gusts and locally heavy rain. Highs today
forecast in the low to middle 80s.
PW values from last evenings sounding near an inch climb to near 1.5
inches by this morning, and toward 2 inches by Saturday evening as
moisture plume streams northward ahead of the upper low, and initial
stronger storm development could bring some training storms and
locally heavy rainfall. As front moves in for the overnight hours
Saturday night, this plume pivots over the eastern counties and
brings the locally heavy rain threat east as it does so. Total
forecast amounts are generally 2 inches or less, but would
anticipate some locally higher amounts as storms train from SW to NE
along the front as it slowly pushes SE. On the downside will be
decreasing instability which could help diminish precip efficiency.
Overnight lows with clouds and rain look to hold in the upper 50s
far northwest to middle 60s southeast.
.LONG TERM...(Sunday through Friday)
Issued at 302 AM CDT Sat Sep 24 2016
By Sunday morning the cold front will bisect the forecast area as it
continues to progress southeastward. At this time the northern
stream trough will be tracking over ND with the one axis extending
southward over central KS. A few of the models are showing an
increase in mid level frontogenesis at this time as well as energy
lifting out of the southern stream, which may enhance the precip
across the southeast half of the forecast area during the morning.
The NAM is most aggressive with this scenario therefore will have
watch the latest trends to see if the artifact is real, and if so
where it may come together. With the possibility of enhanced precip
rates an additional 0.5 to 1 inch of rainfall may be possible, but
confined to east central KS. This area will have to be monitored for
potential flash flooding, which will depend of how much rain falls
late Saturday and overnight. By mid day though the front should exit
the area and most locations will be drying out. North central KS
will pretty much remain dry after sunrise Sunday. In the evening
another mid level trough axis will swing out over the plains forcing
the moisture and lift southward. The Canadian air mass will quickly
move in behind the front supported by a surface high pressure, which
is forecasted to track through the high plains. The coolest low
temperatures will be on Monday and Tuesday mornings with mid to
upper 40s for most locations. While high temperatures stay in the
70s through Friday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 621 AM CDT Sat Sep 24 2016
Tried to get a little better timing on rain chances today, with VC
becoming a tempo then followed by prevailing as precipitation
becomes more stratiform behind convection and as front comes in.
Push of drier colder air is beyond this TAF cycle so prevailing
through 12z. Much water in the column will likely reduce visbys
quite a bit with heaver rain and tempo of 1SM may be too high.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...67
LONG TERM...Sanders
AVIATION...67
Area Forecast Discussion
National Weather Service Bismarck ND
253 PM CDT Sat Sep 24 2016
.SHORT TERM...(This evening through Sunday)
Issued at 253 PM CDT Sat Sep 24 2016
Deep cut off upper level low was centered around southeastern
Montana at 18Z with the associated surface low over southwestern ND.
Dry slot of system was supporting mostly dry conditions across
southcentral ND Saturday afternoon with low level southerly flow in
the warm sector helping increase instability. Dew points in this
area were mainly in the mid/upper 60s and SB CAPE around 1500 J/Kg.
High res models show convection developing after 20Z, with the HRRR
showing the stronger cells just outside our area. Any severe threat
should be relatively short lived and over by 00Z Sun. Also expect
showers and stratiform precip to spread from west to east
overnight as upper low progresses across the state, reaching
southern Manitoba as an open trough by 18Z Sun.
Expect strong winds to develop behind the system as the surface
low reaches northcentral ND this evening. Wind advisory that is
ineffect tonight for the extreme southwest will be expanded to the north
and east. Will also make some adjustments to the starting time as
winds will be a little slower to strengthen than originally
thought. GFS depicts strongest BL winds around 40 kts over this
area. 0.5 km AGL winds also max at around 50 knots near
Adams/Sioux counties at 09Z.
On Sunday, precip will end from west to east and should be
completely out of the area by late afternoon. Breezy to windy
northwest winds will continue through the day as the low pushes away.
.LONG TERM...(Sunday night through Saturday)
Issued at 253 PM CDT Sat Sep 24 2016
A longwave upper level ridge will build over the Plains during the
week leading to mostly dry weather along with a warming trend. High
temps initially in the 60s on Monday will warm to the low 70s on
Tuesday, with similar highs through Friday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1226 PM CDT Sat Sep 24 2016
LIFR and IFR ceilings can be expected through the 18Z TAFs, in
association with showers and isolated thunderstorms that are
projected to move eastward across the state through the overnight
hours. Some storms in eastern areas may become strong this afternoon
and tonight.
Additionally, gusty winds will persist through the 18Z TAF period
with winds predominately become northwesterly through early Sunday
morning.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from midnight CDT /11 PM MDT/ tonight to 6 PM CDT
/5 PM MDT/ Sunday for NDZ019-020-034-042-045-046.
Wind Advisory from 8 PM CDT /7 PM MDT/ this evening to 6 PM CDT
/5 PM MDT/ Sunday for NDZ017-018-031>033-040-041-043-044.
&&
$$
SHORT TERM...JNS
LONG TERM...JNS
AVIATION...AC
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
657 PM EDT SAT SEP 24 2016
.AVIATION...
The large high pressure system across the eastern Great Lakes will
maintain its influence across Se Mi tonight through Sunday evening.
Very dry air associated with this system will maintain mainly clear
skies. Its gradient will support an easterly component to the light
winds.
For DTW...During the overnight, the low level flow will turn
southeast across wrn Lake Erie. This trajectory will place metro
directly downwind of the lake influence. While the gradient may be
too strong to support fog, there is a chance that the moisture flux
off the lake will lead to some low clouds (based at or below 3k ft
given the expected inversion level). Both the RAP and HRRR are in
support of this, the timing of which being between daybreak Sun
through late morning. Still some question as to if the very dry
ambient airmass will support a solid BKN or OVC cig, so just
scattered clouds will be maintained in the TAF attm.
//DTW Threshold Probabilities...
* Low in ceilings below 5000 ft Sunday morning.
&&
.PREV DISCUSSION...
Issued at 330 PM EDT Sat SEP 24 2016
DISCUSSION...
Anti-cyclonically sheared flow aloft this afternoon is supporting
weak subsidence through the troposphere. Near the surface,
east/northeast flow along the southern periphery of a surface high
over northern Ontario will continue to filter a dry/cool airmass
over Southwest Ontario into Southeast Michigan. A coincident weak
lake-effect response can be observed over southern Lake Huron and
Lake Erie. The dry nature of onboarding trajectories is limiting the
lake response to some cloud streamers. Short range guidance
soundings suggest the moist cloud depth will not be sufficient for
precipitation production within the progressively thinning cloud
field. Elsewhere, a batch of mid-cloud has completely succumb to the
deep subsidence over the region. Additional mid-cloud over northern
Lower Michigan will also cascade southeast over the area prior to
sunset while also thinning dramatically.
Skies will generally be clear tonight. The exception will be
locations near the Ohio border where lower-level moisture along the
old frontal boundary over northern Ohio and Indiana lingers
supporting a little more cloud. The ever drying surface layer in
conjunction with light winds and reasonable radiative cooling should
support a rather cool night - lows in the 40s outside the Metro
Detroit urban area.
Aggressively building ridge along the West Coast will shove the closed
low currently over the Continental Divide out onto the Northern
Plains tonight. Height falls forced by a deepening trough over
northern Alberta and Saskatchewan will coax the upper low
northeastward into southern Manitoba Sunday. The composite trough
structure will have an apparent negative tilt structure and the
associated cohesive PV anomaly will briefly lift to the northwest of
the Great Lakes region Sunday night. It will then undergo a
cycloidal redirection to the southeast early Monday, as a robust
upper-level jetlet in the main trough structure over the Canadian
Prairies surges along the resident tropopause undulation. The net
result is the main PV anomaly bulldozing east/southeast across the
Great Lakes region Monday.
During the reorientation transition, the remnant confluent PV
filament over upper Mississippi Valley will flip eastward across the
region Sunday night into early Monday - owing to wavelength
compression dynamics. This PV feature will force mass overturning
resulting in convection along the mid-level frontal corridor. While
ambient instability will be very limited precluding a free
convective release, expect the forced convection to be capable of
generating some thunder.
As the maturing rejuvenated development sequence occurs over Lake
Superior Monday afternoon, the mid/upper level jetlet will drive
significant drying at mid-levels along with appreciable isentropic
decent in the 292-298K layer. Wind speeds in excess of 40 knots
exist in this layer. Boundary layer mixing appears to reach roughly
5kft - supporting access to gust potential around 30 knots during
the afternoon hours.
The system undergoes a fairly rapid barotropic transition Monday
night, which will allow the low-level cloud field in the commahead
to centrifugally expand across Southeast Michigan after sunset.
Low pressure moving southeast across Lake Superior will bring the
continued chance for rain showers, with rumbles of thunder possible
Tuesday afternoon, as we work with weak instability. The chance for
precipitation will continue on Wednesday as the low centers over
Lake Huron. A drying trend is expected late next week as high
pressure builds back into the region. Temperatures will be on a
warming trend, peaking in the low to mid-60s early next week before
warming into the lower 70s by the week`s end.
MARINE...
Northeast winds of 5 to 15 knots will veer to the southeast late
tonight and then increase to 10 to 20 knots on Sunday. During the
day, the strongest winds will focus over the northern half of Lake
Huron. Winds will increase further Sunday night as the pressure
gradient strengthens in advance of an approaching cold front. Expect
wind gusts into the 25 to 30 knots range over parts of Lake Huron
with the southern expansion of 25 knot wind gusts possibly leading
to Small Craft Advisory criteria over parts of the nearshore marine
zones.
This cold front will bring showers to the area Sunday night into
Monday morning. In its wake, southwest flow will veer to the west
quickly with gusts approaching gale force over parts of the open
waters of Lake Huron, particularly during the Monday evening time
frame.
HYDROLOGY...
Low pressure lifting into Northwest Ontario on Sunday will swing a
cold front through Lower Michigan Monday morning. Showers are likely
late Sunday night into Monday, with rainfall totals of a quarter to
half an inch. The progressive nature of the front and lack of heavy
rain producing thunderstorms will be a limiting factor, thus no
flooding is expected.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....SC
DISCUSSION...Mann/AM
MARINE.......DG
HYDROLOGY....DG
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Peachtree City GA
307 PM EDT SAT SEP 24 2016
.SHORT TERM /Tonight through Sunday Night/...
Surface analysis shows a surface low across the panhandle of Florida
with an upper low across southwest Georgia. High pressure dominates
across the north and central part of the state. A few showers have
developed across southwest Georgia, nearer to the low pressure
systems.
The low pressure centers across the panhandle should slowly meander
to the west, while the surface high to the north will slide east.
The chances for precip will still remain low tomorrow, with only
slight chance/low end chance possible. The best chances for precip
will be in the south, nearest the low centers, and in the mountains.
Min/Max temperatures will continue 8-10 degrees above normal through
the period. But, there is hope...(see extended)
NListemaa
.LONG TERM /Monday through Saturday/...
Only tweaks to the long term based on the latest guidance.
BDL
PREVIOUS DISCUSSION...
The extended period begins with high pressure continuing to be
anchored off the northeast coast with ridging down the east side
of the Appalachians and wedge into most of North and Central GA.
Best deep layer moisture profile looks to be within the wedge
itself affecting mainly North and East GA. Instability on the
other hand will be most prevalent for Central portions of the
area...especially with the heating of the day on Mon. All this
points to a nearly uniform pop distribution of low end chance for
most areas but best thunder chances to the south.
By late Mon afternoon and into the evening hours...will be
watching what should be the strongest frontal boundary we have
seen in this early fall season approach the area. Precipitable
water looks to increase to 1.75 inches across northern portions
and Cape values increase as well although GFS most unstable
remains less than 1000 j/kg for this event. Still though...with
relatively cool temps aloft...should see adequate lapse rates to
allow for enhancement of pops and development of at least isolated
thunderstorm activity. Have kept pops below likely for now but
these may need to be bumped up to likely with subsequent
forecasts.
Front is a slow mover initially keeping mid range pops in place
over central GA through Tue. It does eventually move well south
of the area through mid week allowing for the coolest air of the
season thus far. Although highs will only be able to be reduced
enough to get back to climo...indications now are that mins could
go some 3 to 5 degrees below climo with upper 40s not out of the
question...even into west central GA should GFS verify. Will need
to see some more runs indicating this to jump on it and will keep
most locales in the 50s for now.
Deese
&&
.AVIATION...
18Z Update...
Winds will be the main forecast issue for the period. Speeds will
be light and generally average 6kt or less. VWP shows light NW
winds up to around 8kft this afternoon, but as the high center
slides east, the low level direction should swing over to the
east. There could be a brief period near sunset where the winds
will flirt with due north, but again, speeds will be very light. The
RAP has had a better handle on the surface winds...and have chosen
to follow closely. Otherwise, conditions will be VFR through the
period. No precip anticipated.
//ATL Confidence...18Z Update...
Medium confidence on winds. High confidence remaining elements.
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 67 90 68 88 / 5 20 20 50
Atlanta 71 90 70 87 / 0 10 20 50
Blairsville 62 85 62 83 / 5 30 30 60
Cartersville 66 92 67 87 / 0 10 20 50
Columbus 72 93 70 91 / 5 20 20 30
Gainesville 69 89 68 86 / 5 10 20 60
Macon 69 92 68 90 / 5 20 20 30
Rome 65 93 67 89 / 0 10 20 40
Peachtree City 67 91 66 88 / 0 10 10 40
Vidalia 71 90 71 88 / 5 20 20 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...NListemaa
LONG TERM....BDL
AVIATION...NListemaa
Area Forecast Discussion
National Weather Service Grand Forks ND
255 PM CDT Sat Sep 24 2016
.SHORT TERM...(This evening through Sunday)
Issued at 255 PM CDT Sat Sep 24 2016
The main challenge will be pcpn chances tonight and then the
lingering effects of this system into Sunday. As of mid afternoon
the main tstm action has been over southeast SD into southwest MN.
This activity seems to be more focused along the sfc warm front,
which is tied to the sfc low over southwest ND. The main 500 mb
low is also over the western high plains, quite a bit further west
than our FA. Cloud cover has inhibited temps today, but mainly
over northwest MN. Despite the clouds the strong SSE wind push has
brought up mid 60 dew points and temps in the upper 70s to near
80F across the south.
Instability has risen to about what was expected today, in the
500-1500 J/kg range. However, there still has not been much
activity developing other than that further south. Latest SPC HRRR
shows the activity further south lifting up into mainly west
central MN tonight, but it does have a little pcpn poking up thru
the central and northern Red River Valley. The dry slot will try
to push up into the FA later tonight followed by the wrap around
on Sunday. Gusty northwest winds will also kick up on Sunday, but
at this point it looks like the worst of it may brush the Devils
Lake region and areas just west of the valley. Later shifts can
take another look at that.
.LONG TERM...(Sunday night through Saturday)
Issued at 255 PM CDT Sat Sep 24 2016
Upper level low will begin to exit the area Sunday night with
wraparound showers exiting northwestern Minnesota. Clearing to move
in Monday...though may take a bit longer to clear out the far
eastern fcst area than models indicate. Breezy north-northwest
Sunday night into Monday before diminishing Monday evening as high
pressure ridge begins to move in. Clear or clearing out Monday
night all areas with sfc high over eastern North Dakota by 12z
Tuesday. Looks like a cool night and coordinated with BIS/ABR and
dropped lows below model blend guidance and have mostly upper 30s.
Dry Wed-Thu as upper level ridge builds in for dry and a bit milder
airmass. A weak short wave will move in for Friday into Saturday
giving a chance for precipitation. Temperatures will run a tad
above normal late week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1245 PM CDT Sat Sep 24 2016
Winds have been a little slow to materialize in areas that had fog
earlier this morning. Most of the gusts have been at KFAR and
points southward. Main challenge for the TAFs will be any thunder
development this afternoon and evening. Tried to break down a 2-3
hour period that the SPC HRRR is showing the best chances being
during. Other than that, wind gusts should decrease during the
evening, but ceilings will be highly variable. Wrap around pcpn
and low clouds will roll back into the FA on Sunday.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
SHORT TERM...Godon
LONG TERM...Riddle
AVIATION...Godon
Area Forecast Discussion
National Weather Service Grand Junction CO
252 PM MDT SAT SEP 24 2016
.SHORT TERM...(Tonight through Monday)
Issued at 252 PM MDT Sat Sep 24 2016
A few rain and snow showers hanging on late this afternoon in
wrap-around flow as the main upper low continues to lift northeast
into the North Dakota. HRRR and RAP keep the light showers rolling
through late this evening, before shutting things down as mid
level flow becoming more north to northeasterly introducing more
of a downsloping component for much of our forecast area. Cloud
cover will be the big factor with potential freezing temperatures
overnight with our higher valleys the biggest concern. Steamboat,
Craig and Gunnison have all had hard freezes earlier this month
and other guidance in remaining high valleys holds temps up a bit
with clouds and higher surface moisture in place. Will hold off
on an highlights for freezing temps at this time with expectation
that any run to or slightly below freezing will be very late and
short-lived. Secondary concern will be areas of fog in the
valleys late tonight and have this covered in the latest forecast
package.
Sunday and Monday will be dry with high pressure building
overhead. This will result in light winds, seasonal daytime highs
and cool overnight lows.
.LONG TERM...(Monday night through Saturday)
Issued at 252 PM MDT Sat Sep 24 2016
Upper level ridging will be migrating east Monday night and
Tuesday with southwest flow returning by midweek. Pattern looks to
remain dry through Tuesday before moisture starts lifting back
north into the southern zones on Wednesday as the remnants of
another tropical system get caught up in the flow. ECMWF and GFS
in decent agreement with kicking a wave out across the forecast
area Thursday with additional energy to follow through the
weekend. So after a slow start to this extended period, things
will become more interesting as we close out the week with rain
and mountain snow returning to the forecast.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1112 AM MDT Sat Sep 24 2016
Showers will continue through early afternoon across northwest
Colorado and west-central Colorado as the low pressure storm
system over eastern Wyoming continues to track further eastward.
Reduced cigs/vsby is expected among heavier showers with frequent
mountain obscurations through about 21z in snow. TAF sites are
expected to remain light rain with low ceilings until late
afternoon when clearing skies are seen behind the exiting storm.
VFR conditions will prevail this evening through Sunday morning
as a drier airmass takes hold.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
SHORT TERM...JDC
LONG TERM...JDC
AVIATION...MDA
Area Forecast Discussion
National Weather Service Tallahassee FL
315 PM EDT SAT SEP 24 2016
.NEAR TERM [Through Tonight]...
The 8 am EDT regional surface analysis showed a broad area of higher
pressure across much of the Southeast. Vapor imagery and upper air
data showed a strong ridge from the central Gulf Coast to the upper
Midwest, but there was a weak minimum in the height/temperature
fields centered over Tallahassee. The latest RAP analysis did not
show any Q-G forcing associated with this low. Isolated to scattered
thunderstorms have been developing early this afternoon, but most
have been dissipating quickly once they grow into the dry zone
aloft. We expect isolated storms to continue through the afternoon,
mainly near the coast. It`s interesting to note that a few of the
storms today have had a tremendous amount of lightning. Any
remaining storms from this afternoon will dissipate by evening,
though isolated storms will develop offshore toward dawn. Overnight
lows will be in the lower 70s.
.SHORT TERM [Sunday Through Monday Night]...
An upper level low positioned across the western part of the CWA is
expected to move slightly west on Sunday, and then shift eastward on
Monday. The movement of this low will begin to sink a cold front
into the southeast. Ahead of this cold front, winds will shift east
on Sunday and there will be an increase in moisture. A slightly more
active day in terms of coverage can also be expected on Monday, with
PoPs around 30-50%. High temperatures will remain above normal
through the period, with highs in the low 90s inland and upper 80s
along the coast.
.LONG TERM [Tuesday Through Saturday]...
An upper level trough will amplify over the eastern CONUS Tuesday
and move off the Atlantic seaboard on Thursday. The associated weak
cold front will sweep across the CWA Tuesday/Tuesday night with
surface high pressure and drier airmass filtering in Wednesday
through the beginning of next weekend. Dew points are forecast to
drop into the upper 50s to lower 60s across all but the coastal areas
and southeast Big Bend. Pops will be highest on Tuesday (albeit
only 30%). Highs will be in the upper 80s.
&&
.AVIATION [Through 18Z Sunday]...
Isolated to scattered SHRA/TSRA were developing across northwest FL
early this afternoon, including in the vicinity of KTLH and KECP.
However, we expect these storms to become less numerous as the
afternoon goes on, as much drier air aloft mixes with the PBL.
Otherwise VFR conditions will prevail. There is good agreement
among the NWP guidance in low- end MVFR Vis at KTLH around dawn
Sunday, and for low-end MVFR cigs at KVLD. In fact, some of the
guidance shows IFR cigs at KVLD, which will have to be monitored
in subsequent TAF packages.
&&
.MARINE...
Winds are expected to be light (less than 10 knots) and variable
through the middle of the week, with seas around one foot.
&&
.FIRE WEATHER...
No problems.
&&
.HYDROLOGY...
While rain is expected over the next few days, significant
rainfall amounts are not expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 73 91 72 90 71 / 10 30 20 40 20
Panama City 76 88 74 86 74 / 10 40 20 30 20
Dothan 71 92 70 90 69 / 10 30 20 20 20
Albany 71 92 70 90 70 / 0 20 10 30 20
Valdosta 71 90 70 88 68 / 10 20 20 50 20
Cross City 72 90 71 88 70 / 10 20 20 30 20
Apalachicola 75 87 74 85 74 / 10 30 20 30 20
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Fournier
SHORT TERM...Barry/King
LONG TERM...Barry
AVIATION...Fournier
MARINE...Barry/King
FIRE WEATHER...Harrigan
HYDROLOGY...Fieux