Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/07/16
Area Forecast Discussion
National Weather Service La Crosse WI
634 PM CDT TUE SEP 6 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 325 PM CDT Tue Sep 6 2016
The forecast that is most tangible is the next hours and into the
overnight. The greatest potential for flooding and heavy rain has
shifted south into northeast IA, MN-IA border, and
southwest/west-central WI. This is along the outflow boundary
from earlier storms that now lies along a KMCW-KDLL line.
The air mass over IA, south of the outflow boundary, is very ripe
with instability on the order of 3000 j/kg MU/SB CAPE. 19z surface
convergence has increased in nern IA over the past hour, and this
trend should continue. Low-level moisture transport at 850 mb
will increase in the 21Z to 02Z time frame, convergent right into
northeast IA and southwest WI. Air mass is going to be a near
record early September airmass for the Upper Miss Valley: 4.5-5km
warm cloud depth and just under 2" precipitable water. The rain
axis will probably be located very close to that boundary and near
the IA/MN border into central WI, just south of I-90. This air
mass could very easily produce 4-5" in 2-3 hours, with training
echo areas seeing higher than that. This could produce major
flooding if it sets up right. The guidance is pretty close to
consensus /CAMS included/ on this axis area. One possible saving
grace appears to be a faster veer to the low-level moisture
transport seen in the RAP/NAM runs, shifting the convergent nose
east after midnight. We shall see.
Our customers and partners should prepare for potentially
damaging flooding. Nighttime always makes me uncomfortable as
people drive into water without knowing.
Have updated our messaging through the day to focus on that
region a bit more south for flooding, damaging wind, and an
isolated tornado. At 19Z...mesoanalysis of the environment showed
the boundary was weakly capped but the shear environment
supported entry-level supercell tornadoes. We are preparing to
monitor storms very closely on that boundary when they initiate.
Further north the environment is a bit more muddled and while deep
shear is there...it appears bowing segments are preferred in the
more limited CAPE environment. So, away from the boundary,
damaging wind would be a threat through early evening.
Wednesday...Tough, as so much has to happen tonight that will
affect the forecast for Wednesday. After an active overnight
across southwest WI and northeast IA, there is suggestion that
this same area could be impacted by more heavy rain with shortwave
trough support Wednesday. The latest extension hours of the 06.19Z
RAP suggest the low-level moisture convergence will shift
southeast of the area Wednesday morning with a westerly low-level wind.
The 06.18Z nam is not so rapid to scour it east and looks to
develop convergence into southwest WI again in the morning,
intensifying it during the day into sw WI. The same heavy rain air
mass is in place, but the CAPE may be much less. Experience tells
me the rain will likely push the entire mesoscale southeast toward
Highway 20, reducing the heavy rain threat Wednesday. However,
confidence is not high enough yet to back out of forecast, but it
is something to consider.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 325 PM CDT Tue Sep 6 2016
The front becomes progressive and finally scours the soaker air
mass to our southeast by Thursday morning for a cooler less humid
day. It quickly rebounds Thursday night and Friday ahead of a
strong trough for renewed rain chances.
Friday night through Tuesday
Strong upper-level shortwave trough is forecast to move through the
Upper Midwest Friday into Saturday. Models are in much better
agreement than recent days with a broad surface low developing ahead
of the shortwave. 06.12z GFS and 06.00 ECMWF both bring strong low
to mid-level frontogenetical forcing across our area Friday night
into Saturday, providing a good chance of widespread rain showers.
CAPE appears to limited after sunset Friday evening. Saturday should
be cool and breezy, with a few light rain showers possibly lingering
across central Wisconsin as the upper-level shortwave and attendant
surface low depart the region to the east. Models continue to show
ridging through the region on Sunday ahead of a developing upper-
level longwave trough extending from Hudson Bay to the Pacific
Northwest. Both the GFS and ECMWF develop a cold front and bring it
through the Upper Midwest Monday into Tuesday, but the GFS is much
more progressive with this feature. At least scattered showers
and perhaps a few thunderstorms will be possible along and ahead
of the front, so will maintain low PoPs Monday and Tuesday for
now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 634 PM CDT Tue Sep 6 2016
Periods of thunderstorms are expected at the TAF sites this
evening and persisting into the overnight hours. IFR conditions
are expected in the heavier storms. Some of the storms may also
produce gusty winds and heavy rainfall. Plan on ceilings lowing to
around 500 ft and visibilities falling to around 2SM or less at
times. Chances for showers and storms will continue through much
of the day on Wednesday.
&&
.HYDROLOGY...
Issued at 325 PM CDT Tue Sep 6 2016
Biggest concerns are over the very heavy rain air mass over the
area through Wednesday night. Flood Watch was expanded to cover
the entire forecast area. Main axis of heavy rain should
be on KMCW-KDLL region. This may hit northeast IA again and the
terrain area of sern MN, western WI.
Rivers will all be on the rise into the later week.
Believe we will be able to cancel the Flood Watch in the
northwest after the threat diminishes overnight.
&&
.ARX Watches/Warnings/Advisories...
WI...Flood Watch through late Wednesday night for WIZ017-029-032>034-
041>044-053>055-061.
MN...Flood Watch through late Wednesday night for MNZ079-086>088-
094>096.
IA...Flood Watch through late Wednesday night for IAZ008>011-018-019-
029-030.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT/HOLLAN
AVIATION...WETENKAMP
HYDROLOGY...BAUMGARDT
Area Forecast Discussion
National Weather Service Denver/Boulder CO
932 PM MDT TUE SEP 6 2016
.UPDATE...
Issued at 925 PM MDT Tue Sep 6 2016
Additional tstms developing north of Denver and east of I25 this
evening so have to add isold tstms back into the grids for
tonight. Still expect areas of stratus and fog move into the Urban
Corridor fm the north and east after midnight.
UPDATE Issued at 721 PM MDT Tue Sep 6 2016
Latest HRRR does not show any additional tstm development this
evening so will keep the focus for any deep convection where it is
currently in place...the northeast plains generally east of a
Sterling to Limon line. Have dropped the mention of tstms
elsewhere from the grids. Have also cancelled the Red Flag Warning
for North and Middle Parks at 7 pm mdt. Should see fog and stratus
move back into the Urban Corridor for the Northeast Plains by 06z
and continue overnight.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 144 PM MDT Tue Sep 6 2016
Today and Tonight: Skies have cleared for all but the far NE
corner of the CWA, resulting in ample sunshine and and increase
in instability. Surface based CAPE (instability) is modest across
the foothills and urban corridor (700-1000 J/kg) and highest along
the southeast parts of the CWA (Elbert and Lincoln County with >
1500 J/kg). Vertical wind shear is strong enough for a few storms
to become severe with the primary threat being severe hail. With
marginal instability expect just an isolated chance of a few
storms being severe later this afternoon and into the evening.
Storms will be racing off to the northeast under strong and deep
southwest flow. If any storms become supercellular they too will
be moving quickly to the east at 25-30 knots. With that said do
not expect a risk of flood/flash floods given the fast storm
motions. After midnight the remaining storms will continue to move
to the northeast into progressively stable air. Rain chances are
good for the northeast corner of the state late evening and
overnight as the best forcing moves across northeast Coloradointo
Nebraska. Showers and thunderstorms should exit the urban corridor
after 10 PM and exit the rest of the state by 3 AM Wednesday.
Overnight tonight with very shallow moisture near the surface and
light winds, areas of fog will develop east of the foothills after
2 AM. Visibility may be reduced to a half mile Wednesday morning.
The low clouds and fog will burn off fairly quickly Wednesday
after sunrise and with the return of westerly low-level flow.
Wednesday: Westerly flow returns and dries out the atmosphere
across Colorado throughout the day. After the low clouds
dissipate, skies should be mostly clear to partly cloudy and
temperatures will warm into the lower to mid 80s across the
Plains with upper 60s and lower 70s in the mountains. The surface
low pressure system shifts from southeast Colorado into northern
Kansas, leaving very little pressure gradient across the state.
Surface winds across the CWA will be light other than across
higher elevations of Larimer County and Jackson/Grand Counties.
Winds will be in the 15-20 mph range Wednesday afternoon and RH
will be low so there an elevated fire wx concern in those higher
elevation areas.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 144 PM MDT Tue Sep 6 2016
A westerly flow aloft will prevail over Colorado Wednesday night
and Thursday ahead of an upper level trough digging south over the
Pacific Northwest and Northern Rockies. The remnants of Hurricane
Newton will move across the Southern Rockies Thursday. Models in
fairly good agreement keeping moisture associated with it to the
south of the area. The GFS is the only models that brings
precipitation into the forecast area, southern Lincoln county.
Will not mention any showers and storms at this time for Thursday.
The upper level trough will move across Wyoming Friday. A cold front
will move through Thursday night and bring cooler temperatures for
Friday. Not much moisture behind the front, so expect cool
temperatures, mostly clear skies, and dry conditions Friday.
For the weekend, westerly flow will keep dry and mild conditions
over the state. Slight ridging ahead of the next upper level trough
is expect to bring warmer temperatures Sunday.
As the next upper level trough drops south across the western CONUS,
a cold front is forecasted to push south through Colorado Monday.
Temperatures cool to the 70s behind it. May be enough moisture for
showers and storms, so will have 10-30 pops in the forecast with the
best chance being over the higher terrain. Models continue to show a
cool down into Tuesday where highs may only be in the 60s. If the
models are corrected with the timing and track of the upper level
low, widespread rain will be possible over northeast Colorado.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 925 PM MDT Tue Sep 6 2016
Difficult wind forecast this evening to say the least. West/southwest
winds at KDEN expected to transition to north/northeasterly
overnight. Stratus/fog expected to increase fm the north and east
by 06z with ifr cig/vsby restrictions developing at KDEN/KBJC...
with slightly better conditions in the south part of Denver near
KAPA.
&&
.BOU Watches/Warnings/Advisories...
None.
&&
$$
UPDATE...Cooper
SHORT TERM...Schlatter
LONG TERM...Meier
AVIATION...Cooper
Area Forecast Discussion
National Weather Service Cleveland OH
958 PM EDT TUE SEP 6 2016
.SYNOPSIS...
A ridge of high pressure will remain over the region tonight. The
high will weaken by Wednesday which will allow waves of low
pressure to move across the Central Great Lakes Thursday into the
weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
Showers have ended across the area until remnants of upstream
convection arrives later tonight. This activity has trended
southward towards the better instability but has also shown a
weakening trend as it encounters the ridge and warmer mid level
air aloft. New development has been in Wisconsin where the low
level jet will be focused overnight. Still expecting an increase
in cloud cover to spread southeast with time. Will continue with a
slight chance of showers and thunderstorms across far northern
Ohio after midnight with a 30 percent chance across the east end
of the lake towards Pennsylvania. The increase in moisture or a
stray outflow boundary could be enough to trigger a few
thunderstorms towards sunrise.
Previous discussion...Plenty of convective cu across the area
today with dewpoints now into the upper 60s and lower 70s. Radar
shows isolated showers in our area but more so just to our west.
Movement is to the east so would expect these showers to drift
into the western counties late afternoon/early evening. The HRRR
also shows additions showers popping up up central and east so for
the evening will leave a slight chance pop in place. Overnight
there will be activity well to our northwest and this should drift
our way but do not expect it to reach the area. Expect a muggy
night with lows around 70.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Wednesday the surface high will begin to weaken and the upper
heights begin to drop as well. Guidance is conflicted with the
MAV dry and the MET showing a chance or slight chance pop. Given
all that and the fact that capes are forecast to be 2500-3000j/kg
in the afternoon with very little CIN will bring in a chance pop
for the afternoon. Thursday morning thunder chances increase as
the high weakens further...low pressure moves through the central
lakes and a cold front sags toward the area from the north. Will
have low chance or slight chance in the morning but will move up
to high chance for the afternoon. Thursday evening will continue
chance pops...highest east...through the evening drying from the
west after midnight as drier air and high pressure briefly build
in. The front returns as a warm front Friday so will bring pops
back from the southwest during the day. Highs Wednesday upper 80s
to lower 90s...Thursday mid and upper 80s and Friday lower 80s.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
A more zonal pattern with somewhat cooler conditions is expected
during this period. A short wave with associated cold front is
expected to cross the region Saturday with fairly good timing
agreement between the GFS and ECMWF. Scattered to numerous showers
and thunderstorms can be expected with this front. High pressure
will build into the region Sunday and shift to the east on Monday.
850 mb temperatures cool down to 8-10C or slightly below normal.
This should produce surface temperatures slightly below normal too.
The zonal flow will continue into Tuesday with the approach of a
significant short wave across the upper Mississippi Valley. The
exact timing is in question with the ECMWF about a day slower in the
progression of the short wave and associated cold front across the
area Tuesday or Wednesday. It will be rather warm again ahead of the
front but strong cold advection can be expected after frontal
passage and the first feel of autumn.
&&
.AVIATION /00Z Wednesday THROUGH Sunday/...
Models differ tonight into Wed for both possible shra/tsra and for
fog and stratus potential which means low confidence in the
forecast. Think there will be patches of thin cirrus tonight into
Wed and winds will stay up just enough so that maybe only some
patchy mvfr fog forms. Forecast Pops for precip are 20% or less
until later Wed afternoon when they increase just a little more so
will not mention anything in Tafs.
OUTLOOK...Periodic non-VFR possible Thursday through Saturday.
&&
.MARINE...
Tranquil conditions will prevail on Lake Erie into Wednesday with
high pressure located over the Tennessee Valley. We can expect
southwest winds of 5-15 knots. Winds will increase Thursday to
15-20 knots as a cold front approaches and crosses the lake
Thursday night. The front will return north as warm front Friday
night and another cold front will cross the lake Saturday night.
SCA conditions could develop Thursday evening and Saturday night.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...TK
NEAR TERM...KEC/TK
SHORT TERM...TK
LONG TERM...LaPlante
AVIATION...LaPlante
MARINE...LaPlante
Area Forecast Discussion
National Weather Service Cheyenne WY
704 PM MDT TUE SEP 6 2016
.SHORT TERM...(This evening through Thursday night)
Issued at 140 PM MDT Tue Sep 6 2016
Early afternoon water vapor loop showed a high amplitude ridge
over the southeastern CONUS and trough over the western CONUS.
Increasing southwesterly flow aloft prevailed over the Rockies
and plains. Surface front remains stalled from the Upper Midwest
through the central Great Plains and Rockies. Moist east-southeast
flow exists along and east of the Laramie Range with good low/mid
level wind shear and SBCAPES approaching 500 j/kg. The 18Z HRRR
develops a small complex of thunderstorms over Platte County after
20Z, tracking east across Goshen County through 00Z. CYS radar
detected a small thunderstorm southwest of Douglas. Will continue
to monitor radar trends through the late afternoon for additional
development with a marginal/isolated severe threat along the I-25
corridor and far southwest Nebraska Panhandle.
Scattered showers/thunderstorms will continue this evening along
and east of the Laramie Range, with convection ending after
midnight over the southern Nebraska Panhandle. The concern then
shifts to fog/low cloud development across the plains overnight
and early Wednesday morning. Winds veer around to southwest across
southeast Wyoming with drier low levels precluding fog formation.
Wednesday will be warmer with gusty westerly winds throughout the
day. Highs will range from the low 70s to low 80s. Thursday will
be a few degrees warmer but windier along and west of the Laramie
Range.
.LONG TERM...(Friday through Tuesday)
Issued at 140 PM MDT Tue Sep 6 2016
Friday...Progressive and sharp shortwave moving southeastward across
the Dakotas will send a dry cold front across our counties early in
the day, making for an autumnal feeling final day to the work week,
with high temperatures in the 60s to lower 70s.
Saturday...Another pleasant weekend on tap with northwest flow aloft
and a warming trend as heights and thicknesses rise. Maximum
temperatures just about perfect for this time of year for outdoor
activities. Continued dry with limited low and mid level moisture.
Sunday...Warming trend continues in the warm sector ahead of the
next potent cold front and shortwave. Maximum temperatures exceeding
80 degrees east of I-25 with dry airmass and downslope warming due
to west winds. Lack of low and mid level moisture precludes shower
and thunderstorm development.
Monday...Autumnal like feel again as a relatively strong cold front
passes early in the day, knocking high temperatures back into the
60s. The cold frontal passage itself will remain dry, however, moist
southwest flow aloft and localized upslope will aid in producing
scattered showers and thunderstorms in the afternoon, primarily
along and west of Interstate 25.
Tuesday...Shower and thunderstorm chances will gradually decrease
during the day as a ridge aloft develops and strengthens. Low level
southeast winds will keep cool upslope clouds and temperatures along
and east of I-25 with temperatures that may struggle to reach the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 552 PM MDT Tue Sep 6 2016
Widespread IFR/MVFR CIGS will develop by later tonight across
areas to the east of the Laramie Range. Could see patchy fog at
SNY/AIA from 10-13Z. Winds will become southwesterly from 12-15Z,
with the low clouds dissipating. West winds will gust to 20-30 kts
at the southeast Wyoming sites from late morning through the
afternoon on Wednesday.
&&
.FIRE WEATHER...
Issued at 140 PM MDT Tue Sep 6 2016
Elevated fire weather conditions will continue this afternoon
along the Wyoming/Colorado border west of the Laramie range with
low humidities and gusty southwest winds. More widespread near
critical fire weather conditions will exist Wednesday afternoon
as low pressure tracks east across Montana during the day. A Fire
Weather Watch remains in effect for much of southeast Wyoming
with afternoon humidities falling to around 15 percent and west
winds gusting in excess of 25 mph. Stronger downslope winds and
lower humidities are forecast Thursday and critical fire weather
conditions could spread further east into the western Nebraska
Panhandle.
&&
.CYS Watches/Warnings/Advisories...
WY...Fire Weather Watch from Wednesday afternoon through Wednesday
evening for WYZ301-303-304-306-308-309.
NE...None.
&&
$$
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...ZF
FIRE WEATHER...MAJ
Area Forecast Discussion
National Weather Service Des Moines IA
918 PM CDT Tue Sep 6 2016
.UPDATE...
Issued at 916 PM CDT Tue Sep 6 2016
No changes to headlines at the moment. Regarding the severe
potential, uncapped 2000 j/kg MLCapes still exist through the
watch area with 35 plus kts of effective shear on the northern
fridge but convection has been slow to mature after rapid cloud
top cooling near Omaha earlier. Although the severe threat may
diminish over the next several hours, elevated Cape and effective
shear projections still suggest strong/severe storms would be
possible even if the convection turns slightly elevated, mainly
with wind more than hail considering the deep moist airmass. Cost
to benefit ratio isn`t there to cancel yet.
Confidence in heavy rain potential is higher however. The strength
and west to east extent of the H85 moisture transport is extreme
into the low level baroclinic zone from KS into IA with at least moderate
frontogenetical forcing in the lowest 1km. With precipitable
waters around 2 inches, warm cloud depths to 4.5km by daybreak and
very favorable mean wind orientation convection could very well
train along the boundary for a prolonged period realizing the deep
moisture plume ahead of Hurricane Newton. This in many ways
may resemble a Predecessor Rainfall Event. Many high resolution
models suggest two to four inch rainfalls with this system,
include the 01z HRRR and 00z ESRL HRRR.
&&
.SHORT TERM.../Tonight/
Issued at 338 PM CDT Tue Sep 6 2016
Heavy rain threat, timing, and location were the main
concerns for this evening. Flash flooding seems feasible, especially
during the overnight hours along and north of Highway 20. Leaned
toward the latest couple runs of the HRRR as well as the 06.12z
ECMWF and even the 09.15z HopWRF have convection delayed until after
22z this afternoon. Thinking these have the best handle on
convective trends, but slightly too fast WRT initiation. Thus, cut
back on timing and nudged them further north late this afternoon
into the evening.
Water vapor portrays a nice atmospheric river into western to
northern Iowa and the GFS/NAM/ECMWF continue this trend throughout
the night. Frontal boundary extends from west-central Iowa north-
northeast through just south of Estherville into central Minnesota.
PWAT values range from 1.8-2.0 inches tonight into Wednesday morning
across northern Iowa which is about 200% above climatology for this
time of year. Strong moisture transport continues throughout night
and even increases with the LLJ increasing by around 03z Wednesday.
Warm layer cloud depths remain around 4000 meters with MCW BUFR
soundings suggesting fairly deep saturation across northern Iowa.
Surface dew points remain in the upper 60s to lower 70s overnight
with WAA persisting south of the frontal boundary. Decent moisture
convergence and enough forcing is likely late tonight and with the
above mentioned conditions, leaned toward a Flash Flood Watch along
and north of Highway 20. 3-hour Flash Flood Guidance is roughly just
over 2 inches in this area, and that could be realized over some of
the area tonight.
Confidence is low WRT to severe weather potential tonight as shear
remains unidirectional and the low level shear is fairly weak.
Certainly cannot rule out a brief incident of strong winds, but the
deep layer shear and instability looks too weak for any substantial
updraft to produce large hail. The main concern tonight is flash
flooding.
.LONG TERM.../Wednesday through Tuesday/
Issued at 338 PM CDT Tue Sep 6 2016
Thunderstorm chances will continue on Wednesday with the focus
area settling south into central Iowa. The biggest variable will
be overnight outflow boundaries and how far these may settle. Mid
level moisture transport (700-500 mb) streaming north from the
Pacific and low level moisture transport from the Gulf of Mexico
will converge over central Iowa by Wednesday morning and into the
afternoon. The deep moisture advection will push PWAT values up to
2.25 inches or nearly 250 percent of seasonal values. Storm
motions of 25 to 35 mph will allow storms enough residence time
for heavy rainfall due to expected high rainfall rates. In
addition, storm motions will become nearly parallel to the
boundary with the potential for training of storms. Current
headline likely will need to be shifted further south for
Wednesday but current headline will allow future updates based on
how the overnight convection evolves.
Severe weather will generally be low on Wednesday. Expect a mid to
high level cloud debris from overnight storms may linger over the
area much of Wednesday and limit the strength of instability and
reduce the severe weather threat. Saturating soundings will limit
the large hail threat thus the main threat for severe weather will
be damaging wind gusts.
Thunderstorm chances will linger over the southeast Wednesday
evening before drier air arrives leading to a dry Thursday.
Moisture advection will quickly move back north Thursday night
into Friday as the remnants of Hurricane Newton lifts into Kansas
and northern Missouri. As this occurs a strong short wave trough
will approach from the west bringing good forcing through the
region. Expect scattered elevated storms Thursday night followed
by surface based activity on Friday as the upper trough and
attendant surface boundary arrive. A few severe storms and locally
heavy rainfall will again be possible. Cooler and mostly dry this
weekend with the arrival of high pressure. Return flow develops
early next week as the high departs brining additional storm
chances.
&&
.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 716 PM CDT Tue Sep 6 2016
Category and thunder confidence is fairly low through the period
due to evolving convective trends. It will be difficult to
predict what could potentially be a wide range of conditions at
any particular TAF location in time due to storms and associated
cloud/visibilities so have depicted a tempered broad-brush until
trends can become cleared. Lower categories and longer thunder
periods are certainly possible but not shown as of yet.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Wednesday evening for Black Hawk-
Bremer-Butler-Cerro Gordo-Emmet-Franklin-Grundy-Hamilton-Hancock-
Hardin-Humboldt-Kossuth-Palo Alto-Pocahontas-Webster-Winnebago-
Worth-Wright.
&&
$$
UPDATE...Small
SHORT TERM...Podrazik
LONG TERM...Donavon
AVIATION...Small
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1151 PM EDT TUE SEP 6 2016
.AVIATION...
Area of showers and thunderstorms stretching from Lower Michigan
back through Wisconsin will be maintained in at least a scattered
form over Southeast Michigan by steep low-level lapse rates, a
nocturnal low-level jet, and additional moisture advection up into
Michigan. Some uncertainty as to how well it will hold together
however as Southeast Michigan remains more under the influence of
upper ridging centered over the Southern U.S., providing a layer of
warmer air in the mid-levels that is not present to our north and
west. Showers and possibly a few thunderstorms look to mainly have
an impact on FNT and MBS, but could also brush PTK. Other concern
for late tonight will be potential development of BR. The potential
for this will be lessened if we do see any organized area of
showers/tstorms affect any of the terminals. Slight southwest
gradient should however keep restrictions limited to MVFR.
Renewed chances for showers and thunderstorms will exist on
Wednesday, especially by late afternoon and evening as heat/humidity
build and as cooling in the mid-levels helps to destabilize the
atmosphere.
For DTW...
//DTW Threshold Probabilities...Area of showers and thunderstorm
stretching from Central Michigan back through Wisconsin will likely
remain north of DTW. Mostly clear skies will bring potential for BR
development late tonight, but light southwest gradient should keep
visibilities at MVFR. Uncertainty surrounding thunderstorm
development in the DTW airspace tomorrow is high given only weak
forcing in a hot and unstable atmosphere, but best potential will be
during the afternoon and evening.
* Low for ceiling 5000 ft or less tonight. Moderate tomorrow
afternoon.
* Low for thunderstorms until late tomorrow afternoon and evening.
&&
.PREV DISCUSSION...
Issued at 957 PM EDT Tue SEP 6 2016
UPDATE...
Weak low-level jet and theta-e advection, combined with steep
low-level lapse rates through the first half of the night should
help maintain at least a scattered coverage of showers and
thunderstorms as the band of current convection stretching from
Western Michigan back through Wisconsin moves east. It will be
moving into a less hospitable environment in Southeast Michigan,
which is more under the influence of upper ridging/mid-level
warming and where 00Z KDTX raob showed some drier air in the mid-
levels. Main area impacted should be along and north of the I-69
corridor counties per latest HRRR and based on radar trends. Made
some adjustments to pops in forecast update to account for this.
PREV DISCUSSION...
Issued at 306 PM EDT Tue SEP 6 2016
DISCUSSION...
Hot and humid this afternoon as max temperatures reached around 90
degrees and dew pts reside in the low to mid 70s.
Upper level ridge in place (592 dam at 500 MB per 12z DTX raob) over
southeast Michigan will gradually weaken as multiple upper waves/pv
filaments stream out of the four corners region, allowing for
increasing chance of showers and thunderstorms over the next 48
hours as deep moisture plume and surface frontal boundary sags
south into southern Lower Michigan. Latest HRRR supports most of
the upstream activity dissipating as it encounters the ridge,
coupled with loss of daytime heating (which pushed MLcapes to 2000
J/kg per 18z spc mesoscale analysis). Isolated shower activity
noted this afternoon, roughly along and downwind of irish hills
where slightly better low level moisture resides. Unfavorable/general
subsidence underneath ridge axis, coupled with dry and warm mid
levels has and should continue to hold activity mostly in check.
Tomorrow remains challenging forecast as ridge still looks to be
holding up fairly well, as heights remain at or above 588 DAM, with
700 mb temps aoa 10 C. None-the-less, MLcapes on the order of 1000-
2000 J/kg with weakening to NIL Cap during the afternoon, and with
very moist airmass (PW values above 2 inches), will only takes a few
cells to get going with renewed activity on any outflow boundaries,
as highs are expected to be around 90 degrees again. With the
isolated activity generated this afternoon, felt compelled to
increase pops a little bit tomorrow (20 south to 55 near Saginaw
Bay), as there is surface trough/warm front noted in 12z euro
lifting through southeast michigan toward 00z Thursday. If night
shift has increased confidence in activity not materializing across
southern half of the cwa, may need heat advisory for Detroit Metro
Area as heat indices push toward 100 degrees once again.
Upper level trough axis over Pacific Northwest this afternoon will
move into the Upper Mississippi River Valley by Thursday morning,
helping to direct and capture an upper wave and associated tropical
moisture coming out of northern Mexico, with descent agreement
amongst Euro/Canadian/GFS/NAM, indicating a surface low tracking
through northern Lower Michigan or the Straights Wednesday
Evening/Night, driving cold front and tropical moisture (up to 8 c
dew pt at 700 mb) east through the cwa Thursday Morning, worthy of
high chance to likely pops. Jet forcing displaced to north is the
reason for more conservative pops farther south. If the front is a
bit slower and we get better surface heating on Thursday (forecasted
maxes currently low/mid 80s), severe storms will become concern as
0-6 KM Bulk shear ramps up through the day, exceeding 30 knots.
Surface high building in for Thursday night may set us up for fog as
enough surface/near surface moisture lingers and fails to mix out,
especially if we receive heavy rainfall Wednesday Night/Thursday.
Low pressure system moves up from the central plains Friday/Saturday
continuing chances for showers and thunderstorms for the first half
of the weekend. High pressure is expected for Sunday/Monday with
another weather system dropping out of the north toward mid-week.
High temps in the 70`s with lows in the 50`s through the period.
MARINE...
Prevailing southerly winds will remain modest in speed through
Wednesday as the region settles into a hot and humid stretch
downstream of a slowly approaching frontal boundary. Greatest
potential for thunderstorms through this time will exist along this
boundary stretching into central and northern sections of lake Huron.
Low pressure lifting along this boundary will bring an increasing
potential for thunderstorms all locations Wednesday night into early
Thursday. The passage of this low will prompt a brief increase in
southwest flow early Thursday, before diminishing as winds veer to
west and then northwest to finish the week.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....HLO
UPDATE.......HLO
DISCUSSION...SF/DE
MARINE.......MR
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Sioux Falls SD
1035 PM CDT TUE SEP 6 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 319 PM CDT Tue Sep 6 2016
Tricky forecast in the short term with many different areas of
concern for the region. Current analysis shows a frontal boundary
set up across the southeast corner of the forecast area, roughly
from near Windom to Sioux City. Ahead of the front, dewpoints remain
in the lower 70s with temperatures creeping into the lower 80s. Most
models are having difficulty with the ongoing environment, however
the HRRR seems to have the best handle on the initial conditions and
precipitation trends. Instability is as high as 1500 j/kg in the
Storm Lake area, in a weakly capped environment. With bulk shear up
around 40 kt, think that severe weather will be possible in the
narrow corridor ahead of the front from around 5 pm to 9 pm this
evening.
Elsewhere, copious low stratus blankets the region near and west of
the boundary, and is even producing some patchy drizzle or
sprinkles. Think that precipitation chance this evening are fairly
low in the more stable environment. Expect isolated to scattered
showers with enough meager elevated instability to produce a few
lightning strikes through the evening.
Later tonight, the main upper level trough shifts into the northern
Rockies while a mid level shortwave lifts into the central and
northern high Plains. With stronger lift and support arriving after
midnight, showers and storms will again become likely, particularly
across far southeast SD, northwest IA and southwest MN late this
evening through the overnight hours. With the wave moving northeast,
scattered showers and storms remain in the picture through the day
on Wednesday, finally beginning to taper off in south central SD in
the afternoon. Severe threat looks very marginal for activity on
Wednesday. Shear is fairly high, but instability and meager lapse
rates may be more of a limiting factor. As it does not looks like
much of a break from the activity tonight into Wednesday, think that
clouds may limit the potential instability. Precipitable water
values remain somewhat high, but with the heaviest rainfall expected
southeast of where the recent heavy rainfalls occurred, do not think
there is enough of a threat of flash flooding for a watch at this
time.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 319 PM CDT Tue Sep 6 2016
High pressure will drift eastward into the CWA late Wednesday
afternoon, and should lead to fairly rapid downtrend in PoPs by the
evening. This break will be shortlived however as trends continue to
support increasing PoPs Thursday night into Friday as a rather
progressive upper wave pushes through the Northern Plains.
Instability is not that great, so severe weather risks are low. We
will be looking at scattered showers and occasional thunderstorms
into Friday afternoon.
Cooler Canadian high pressure will surge into the area late Friday
and race into the Ohio River Valley by Sunday. A pleasant and dry
weekend is anticipated. Temperatures will fall into the 40s to low
50s in many locations, with high temperatures in the lower 70s.
No strong push of return flow into next week, which should allow a
frontal boundary to move into the area on Monday with little
impact. A deeper surge of Pacific moisture arrives Monday night
and Tuesday, bringing an increased chance of rain to the forecast
in the outer periods of the forecast.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1033 PM CDT Tue Sep 6 2016
Unsettled weather will continue through much of the TAF period
with periodic shower and thunderstorm chances into late Wednesday
afternoon. MVFR ceilings will be present across much of the area
overnight into Wednesday morning, with some improvement by
afternoon.
&&
.FSD Watches/Warnings/Advisories...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...
LONG TERM...Dux
AVIATION...JM
Area Forecast Discussion
National Weather Service Wilmington NC
937 PM EDT TUE SEP 6 2016
.SYNOPSIS...
High pressure both at the surface and aloft will keep the
weather sunny and warm for the remainder of the week. A very weak
cold front will drop into the area Sunday and sink southward
through Tuesday. This will temper the heat slightly and bring some
very low rain chances.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 930 PM Tuesday...Quiet night on tap with clear skies.
Temperatures are expected to fall into the mid to upper 60s inland
to around 70 at the beaches. There HRRR visibility fields was showing
a possibility of patchy fog (> 3 miles) after midnight...but the
latest run has removed it so confidence is not that high for the
fog to develop.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 2 PM Tuesday...Primary headline this period is a gradual
and slight warming trend of both max/min temps as SW flow becomes
fully established across the region. No rain in this period as the
atmosphere carries exceedingly low moisture content. Maximums will
climb 2-4 degrees above normal this period, with a mild morning
start THU/FRI at daybreak.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 3 PM Tuesday...Moisture will be hard to come by for the
remainder of the work week as mid level ridging suppresses it to our
south. In the low levels flow will be light enough to preclude much
in the way for anything more than weak surface layer advection of
surface dewpoints for a little late summer humidity. The upper ridge
breaks down on Saturday and a weak piedmont trough develops.
Normally this would favor a return of low rain chances but no models
really show any so will leave forecast dry at this time. A front and
weak upper trough arrive on Sunday at which time small POPs are
finally introduced and we see lower high temperatures but ones that
are still above climatology. The front will spend Monday and Tuesday
only slowly sinking southward while weakening. A slightly cooler
airmass may push in weakly from the north and rain chances will
remain in the forecast, though rather minimal.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
As of 23Z...VFR conditions will prevail through this TAF valid
period. Moisture remains limited throughout the column. Winds will
back from a westerly direction Wednesday morning to a southwesterly
direction Wednesday afternoon as a seabreeze develops and pushes
inland.
EXTENDED OUTLOOK...Outside of patchy fog around daybreak with
best confidence inland terminals, VFR expected through Sat.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 930 PM Tuesday...At the CMAN and the buoys, the winds are
running less than 10 knots from the southwest. Seas continue at
2-3 feet with an easterly swell of 2 feet every 9 seconds.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 2 PM Tuesday...Summer-like pattern in place WED/THU across
the waters as Bermuda High pressure circulates a SW wind of 10-15
KT, with periodic gusts to 20 kt inshore during afternoons. The
swell contribution from the ENE from post-tropical Hermine curling
ashore will wane and fade this period, as SW-WSW wind-waves begin
to take front stage and center. ESE waves 1-2 ft every 9-10 seconds
will remain in the mix, although higher wave energy will debut in
the form of 4-5 second SW waves late WED into THU. No TSTMS on the
0-20 NM waters WED or THU.
LONG TERM/FRIDAY THROUGH SUNDAY/...
As of 2 PM Tuesday...Piedmont trough washes out on Friday
allowing for abating wind and seas. There will be just enough of a
presence of the west Atlantic high to keep the flow out of the SW
through the period even as speeds fall to just 10kt by Sunday.
Waves will spend the long term settling to just 2 ft as most of
the 3 footers should be gone by Saturday if not Friday night.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
NEAR TERM...HAWKINS
SHORT TERM...MJC
LONG TERM...MBB
AVIATION...SRP
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
846 PM CDT TUE SEP 6 2016
.SYNOPSIS...
Issued at 308 PM CDT Tue Sep 6 2016
The 12z H5 analysis from this morning had a stagnant
pattern across the lower 48 with no significant ht rises or falls
noted. High pressure was anchored across the southeastern states and
located over the delta region of Mississippi. A trough of low
pressure extended down the west coast of the CONUS with a tandem of
shortwaves noted from central Nevada south to southern California. A
50+ KT jet streak extended from northeastern Wyoming into western
Ontario. Hermine was present just to the south of Long Island New
York. At the surface: Low pressure was located over southeastern
Colorado as well as north central Kansas. A cold front extended from
west central Kansas into south central and east central Nebraska.
north of the front, a shield of low clouds was present across all of
western and north central Nebraska. east of the front, strong
southerly winds and hot temperatures were present across most of
Kansas and southeastern Nebraska. Across western and north central
Nebraska under mostly cloudy skies, temperatures as of 3 PM CDT
ranged from 66 to 70 degrees.
&&
.UPDATE...
Issued at 844 PM CDT Tue Sep 6 2016
A new forecast is out using the RAP...HRRR...ESRL HRRR for pops
and qpf. The storm activity is slower to develop and could be less
widespread than earlier forecast. POPs are lower to 50 percent.
UPDATE Issued at 654 PM CDT Tue Sep 6 2016
The RAP...ETA...SREF...ESRL...HRRR...MET and MAV guidance all
show fog forming tonight across much of the sandhills and
southwest Neb. The fog should be fairly widespread by 7 am CDT Wednesday
and lift by 10 am CDT. A new forecast is in place for this
feature.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 308 PM CDT Tue Sep 6 2016
General southwest flow aloft continues across the region. A subtle
wave is currently located across western Colorado per water vapor
imagery. This feature will move northeast tonight, and will aid in
the development of scattered thunderstorms from southwest through
central and portions of north central Nebraska. In addition to the
wave, a southerly low level jet will develop this evening across
Kansas. The low level jet will help increase lift along and north of
a stationary front that will be located across northern Kansas to
eastern Nebraska. Computed cape at H750mb will increase to around
2000 J/KG by mid evening across portions of southwest and central
Nebraska, and with strong shear present expect a few stronger to
perhaps isolated severe storms with large hail.
The front in Kansas will lift north as a warm front Wednesday
morning, with a continued threat of scattered showers and
thunderstorms. The front will be forced southeast of the area as a
cold front by late afternoon as a shortwave aloft advances east into
the Dakotas. This will keep any surface based thunderstorm
development east and southeast of the area along the front. As the
front moves east, drier air both at the surface and aloft will begin
to filter into the region with increasing sunshine Wednesday
afternoon.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 308 PM CDT Tue Sep 6 2016
mid term...Wednesday night through Friday: Precipitation chances in
association with a warm front Thursday night into Friday is the main
forecast concern. Surface high pressure will build south into
western and north central Nebraska Wednesday night, then track east
into Iowa by Thursday afternoon. The high will force the stationary
front, anchored over western Kansas and southeastern Nebraska into
southwestern and eastern Kansas Wednesday night. Overnight lows will
dip into the lower to middle 50s in the central and east with upper
40s in the northwestern sandhills. In general, there is fair
agreement with where the surface high will be located at 12z
Thursday between the NAM and GFS solutions. The GFS is slightly
further south with the high, with the MAV guidance cooler compared
with the MET guidance. For this forecast, blended the current
inherited forecast with the warmer MET numbers. This resulted in a
slight downward trend in lows from the inherited forecast, but not
as pronounced as straight MAV guidance would be. On Thursday, the
surface high will quickly move east into Iowa. At the same time, low
pressure will begin to deepen over western South Dakota with a
surface trough extending south to a second low pressure over
southeastern Colorado. Southerly winds east of the trough will
increase Thursday afternoon. This along with some decent low level
warm air advection behind the exiting surface high, will push highs
into the lower to middle 80s. Slightly cooler temps are possible in
the eastern forecast area, as low level moisture and cloud
development is possible Thursday afternoon. By Thursday night, mid
level warm air advection will increase east of an approaching
northern stream H5 trough of low pressure. Thunderstorms will be
possible along and east of the surface trough where favorable low
level moisture exists. Further west, conditions will be much less
favorable for precipitation as low level moisture west of the
surface trough is meager. The northern stream mid level trough will
lift into northern Minnesota on Friday. This will force the surface
trough east of the area by Friday afternoon. Precipitation chances
will quickly exit the forecast area by late afternoon with partly to
mostly cloudy skies expected. Highs Friday will be somewhat cooler
than Thursday`s highs with readings in the mid 70s expected.
However, highs were trended up slightly from the super blend
forecast as the coolest air behind the exiting system will be
located over the Dakotas. Across the forecast area, H85 temps Friday
afternoon range from 13C in the north to 17C in the south. With
plenty of mixing expected behind the front, felt the All blend
guidance was a tad on the cool side given the decent mixing behind
the front and H85 temps in the mid teens.
long term...Friday night through Tuesday: Strong subsidence will
development behind the exiting trough of low pressure Friday night
into Saturday. High pressure will build into the region Saturday
with return southerly flow developing on Sunday. After highs in the
70s Saturday, highs will reach the 80s for Sunday. A cold front will
bring the next chance for precipitation Monday into Monday night.
Much cooler temperatures will arrive Monday with highs in the 70s,
followed by 60s on Tuesday. The latest EC from this morning has H85
temps of 5-9C on 00Z next Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 649 PM CDT Tue Sep 6 2016
The RAP...ETA...SREF...ESRL...HRRR...MET and MAV guidance all
show fog forming tonight at KLBF and KVTN. The fog should be
fairly widespread by 12z Wednesday. VFR is expected by 00z
Wednesday across all areas. Flight conditions will improve from
west to east Wednesday morning. Confidence is moderate.
Thunderstorm chances overnight and Wednesday morning are not as
high. The latest model consensus suggests KS and southeast Neb
would experience more widespread coverage. There is a large spread
in the HRRR...ESRL HRRR...NAM12...NAMDNG solutions north and south
across Nebraska. Some storm activity is underway across Ern
Wyoming and Northeast Colorado but it appears the best focus is
along a cold front stretching from Lamar Colo...to Hill City KS to
Omaha Neb. The model consensus suggests scattered to perhaps
widespread coverage from KIML to KONL including areas east.
&&
.LBF Watches/Warnings/Advisories...
None.
&&
$$
UPDATE...CDC
SYNOPSIS...Buttler
SHORT TERM...Taylor
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
852 PM CDT TUE SEP 6 2016
.UPDATE...
Increased slightly rain chances in far northwestern Oklahoma for
the rest of tonight. Also, increased sky cover across much of
western Oklahoma tonight.
&&
.DISCUSSION...
A few showers and thunderstorms may affect northwestern Oklahoma
after 11 PM tonight.
Isolated to numerous thunderstorms over far southwestern Kansas
and the Texas and Oklahoma Panhandles as of 845 PM are expected to
continue to move east over the next several hours, but should
weaken as they encounter a strongly capped environment.
Regardless, based on latest radar trends and HRRR model guidance,
increased rain chances late tonight west of an Alva to Woodward to
Cheyenne line. If storms hold together, they could produce brief
gusty winds up to 40 mph as well as heavy downpours.
Otherwise, the forecast tonight is in good shape. Products will be
updated shortly.
MBS
&&
.PREV DISCUSSION... /issued 632 PM CDT TUE SEP 6 2016/
AVIATION...07/00Z TAF ISSUANCE...
VFR mid level scattered to broken ceilings will persist through
sunset into the overnight hours. Similar to today, a MVFR stratus
deck is expected to develop across the region, impacting most
sites near dawn and for several hours after sunrise. Winds will
remain out of the south for the duration of the period. Winds will
be breezy to gusty, with sustained winds 10 to 15 knots and gusts
approaching 25 knots at times.
Kurtz
PREV DISCUSSION... /issued 303 PM CDT TUE SEP 6 2016/
DISCUSSION...
Other than increasing rain chances in northwest Oklahoma, there
will be only minor changes to the weather conditions over the next
three days. Then, a cold front will bring a much higher chance of
rain to most of the region Friday night, followed by cooler and
drier conditions for the weekend.
Warmth and moisture will begin to increase again early next week,
then a second cold front is expected around Tuesday, bringing
another shot of cooler conditions.
The remains of Hurricane Newton will add to the rainfall
potential for the latter part of this week. Although flooding is a
possibility, especially over small areas, major/widespread
flooding appears unlikely at this point.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 74 92 75 92 / 0 10 30 40
Hobart OK 74 93 75 94 / 10 20 30 30
Wichita Falls TX 74 95 75 97 / 0 10 10 10
Gage OK 73 89 71 92 / 30 40 30 40
Ponca City OK 76 92 76 90 / 10 30 40 50
Durant OK 73 94 75 94 / 0 0 10 10
&&
.OUN Watches/Warnings/Advisories...
OK...None.
TX...None.
&&
$$
17/04
Area Forecast Discussion
National Weather Service Pittsburgh PA
1035 PM EDT Tue Sep 6 2016
.SYNOPSIS...
Warm and humid conditions are expected the rest of the week, along
with periodic shower and thunderstorm chances as disturbances
cross the region.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
No major changes were made for the early evening update. Previous
discussion follows.
Weak warm, moist advection has resulted in
isolated showers generally west of I-79, with a ridge axis to the
east maintaining dry weather. The showers should diminish later
this evening with dry weather expected overnight. With higher dew
points in place, lows should average around 10 degrees above the
seasonal average.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Diurnally driven instability is progged to increase on Wednesday,
though persistent ridging should limit any showers and
thunderstorms to isolated in coverage as convective temperatures
are reached. Any precip should end Wednesday evening as
instability wanes.
The ridge is progged to break down and move east of the area
Thursday. Increasing shortwave support and an associated cold
front should result in shower and thunderstorm chances especially
later Thursday and Thursday night. The front is expected to stall
south of PIT early Friday before another shortwave in southwest
flow pulls it back north as a warm front late Friday. This should
result in another chance for showers and thunderstorms. Warm and
humid conditions are expected to continue with temperatures well
above seasonal levels.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Shortwaves embedded in southwest flow should continue shower and
thunderstorm chances until the passage of an upper trough and
associated cold front Saturday night. Ridging thereafter should
result in dry and cooler conditions Sunday through early next
week.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
The last couple rounds of model guidance has been inconsistent in
low-level moisture advection over the past couple hours, however,
have left IFR stratus/fog in the latest TAFs as cloud coverage
remains limited and surface temperatures should be able to cool
down to crossover temperatures by early morning. Also, although
RAP soundings show an unfavorable hydrolapse, dewpoints in
general increased as we were well mixed and suspect guidance may
be underdone.
Mixing should dissipate any fog and lift ceiling levels to VFR by
early afternoon as stratus transitions into a CU layer. With
diurnally fueled instability, a few showers/thunderstorms are
possible Wednesday but ridging should limit coverage and preclude
a TAF mention.
.OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/...
Periodic restrictions are possible in showers and thunderstorms
Thursday through Saturday with several crossing fronts.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.
&&
$$
...Update to aviation forecast discussion...
.SHORT TERM...(This Evening through Wednesday)
Issued at 316 PM CDT TUE SEP 6 2016
Recent water vapor imagery showing southwest flow continuing
locally with upper wave rotating east into the Northern Rockies.
Some moisture aloft evident moving northeast across northwest Kansas
with diurnal cumulus field again developing in a moist atmosphere.
PW values were already near 1.8 inches per RAP analysis. Frontal
boundary was rather stationary from west central Kansas to northeast
Nebraska though little if any cumulus has formed there.
With little large scale forcing near it, the boundary looks to move
very little tonight into Wednesday afternoon. The main concern is
the increasing moisture through the column and any weak waves that
can move through the southwest flow to produce precipitation. The
models vary on this, but do steadily bring precip into the area
through the day Wednesday. Instability is rather limited with mid-
level lapse rates steadily decreasing with time. The warm and moist
atmosphere will keep some instability in place especially in the
daytime of Wednesday. With moderate winds aloft, enough shear will
be in place for at least minor concern for severe weather Wednesday
afternoon. Speeds aloft should be enough to keep precip moving, but
any activity able to train would present a heavy rain concern. At
this point, there aren`t any obvious training setups identified. In
the short term, will need to watch any activity to the west making
its way into north central Kansas this evening but this scenario
continues to be less likely in recent HRRR runs. In general have
slowed the onset of precip chances with time but most locations
should see decent chances for something by late Wednesday afternoon.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 316 PM CDT TUE SEP 6 2016
Wednesday Night through Saturday Morning...
For Wednesday night through Friday night, There is not much change
in the forecast thinking as models continue to show a moist and
modestly unstable airmass with deep layer shear on the order of 30
to 40 KT. By Friday evening, the cold front finally pushes through
the forecast area. So the period continues to look unsettled. The
biggest uncertainty is what forcing may impact the forecast area.
There is some spread in the models with the remnants of Newton
coming up from the southwest ranging from taking it to the south
across OK or bringing it across the forecast area. The NAM seems to
be the only solution taking the energy as far south as central OK.
Therefore think its solution is an outlier and prefer a blend of the
GFS/GEM/ECMWF. So there may be a subtle wave move across the area
Wednesday, remnants of Newton moving across the area Thursday, then
the front pushing through on Friday. The forecast has chance to
likely POPs through the period with them finally tapping off late
Friday night as the front starts to push out of the area. Increased
moisture and chances for precip argue for highs to be in the 80s.
This is supported by a gradual cooling in the 850MB temps and
lowering of 1000-500MB heights. Lows are forecast to remain mild
(lower 70s) Thursday and Friday morning as the cold air advection
holds off until Friday night.
Saturday Night through Tuesday...
A touch of "fall" will return for the upcoming weekend! Low
temperatures will dip into the low to middle 50s Saturday night.
High temperatures will remain comfortable in the upper 70s to near
80 Sunday afternoon! Thunderstorm chances return Monday afternoon
through Tuesday evening as a strong cold front pushes across the
area. Mid-level flow remains relatively weak with the frontal
passage, therefore do not expect severe weather. High temperatures
Tuesday afternoon are expected to be in the low 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 610 PM CDT TUE SEP 6 2016
Low level wind shear is forecasted for later this evening through
sunrise tomorrow. There is a chance for showers and storms
tomorrow, but the higher confidence is during the afternoon hours.
Brief periods of heavy rainfall may restrict visibilities and
cause gusty winds.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...65
LONG TERM...Baerg/Wolters
AVIATION...Sanders
Area Forecast Discussion
National Weather Service Tucson AZ
438 PM MST TUE SEP 6 2016
.SYNOPSIS...A good chance of showers and thunderstorms today,
then abundant moisture associated with Hurricane Newton will bring
periods of showers and thunderstorms later tonight into Wednesday
evening. Locally heavy rainfall, flash flooding and strong winds
will likely occur. The track of Newton may bring it into Southeast
Arizona still at Tropical Storm strength. Lingering moisture will
maintain a few thunderstorms Thursday into this weekend.
&&
.DISCUSSION...Moisture has increased as expected over the past 18
hours, with the 12z KTWC sounding at 1.1 inches, the 18z at 1.3
and current estimates from CIRA LPW totals at 1.4 to 1.6 inches.
That will continue to increase as Newton pushes in from the south
over the next 18 hours with 1.8 inch values immediately south of
the border and values well in excess of 2 inches currently
associated with the storm. Scattered showers and thunderstorms
will continue through the afternoon and evening hours.
So far, conditions have been perfect for guiding a tropical system
into Southeast Arizona. Larger scale features including a trough
to our west and northwest and a strong high centered east of our
area have been close enough to create an environment allowing
a relatively quick track northward, while not being so close that
they inhibit storm development by introducing too much shear.
Newton continues to have great forward speed as it exits the Baja
Peninsula and tracks through the Gulf of California over the next
few hours. The current NHC track has him moving quickly enough to
still be at Hurricane at second landfall west of Hermosillo
tonight, and then still at tropical storm strength as it
approaches the border from the south tomorrow morning. If the
trough influence continues to lift northward as expected, we could
have Newton still at tropical storm strength as he crosses the
border. With that in mind, we have a wind advisory for much of the
area tomorrow, with a High Wind Watch for southern mountains. If
he holds close to the current NHC forecast we may end up needing a
High Wind Watch for all of Santa Cruz county and at least the
southern half of Cochise County.
The bottom line is Hurricane Newton is still holding course and
speed with solid agreement between operational forecast models as
well as most tropical models. This continues to increase our
confidence in heavy rain forecast with 1 to 3 inches expected in
valley locations and isolated higher amounts possible, especially
closer to the border. Mountains are expected to see 3 to 4 inches
with 5+ inches possible in a few locations, again especially
closer to the border. The main area where we may be underdoing the
forecast is Santa Cruz county, where valley amounts could average
2-4 inches with locally higher amounts.
The decaying and sheared remnants will be out of the picture
tomorrow night with a corresponding rapid decrease in storm
chances. There will still be decent amounts of moisture around late
Thursday into the weekend, however the atmosphere will be trying
to transition back into a more mid latitude profile and will
struggle to keep significant thunderstorm coverage on the table
until Saturday or Sunday, when things should be sufficiently
recovered
&&
.AVIATION...Valid thru 08/00Z.
Expect an increase in coverage of SHRA/TSRA late this afternoon
under cloud decks of 6-10k ft agl as Newton approaches rapidly from
the S. Locally heavy rain and MVFR CIGS/VSBY is likely with stronger
storms. Numerous to widespread SHRA and ISOLD TSRA will continue
overnight and through the day Wed. SFC winds SLY 8-15 kts outside of
TSRA gusts into tonight. On Wed, the remains of Hurricane Newton
will pass across the area with the potential for a very strong winds
mainly between 07/15z and 08/00z. Sustained winds of 25 to 30 kts
with gusts to 40 kts will primarily affect the KOLS, KALK, KFHU and
KTUS terminals. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Expect an increase in coverage of showers and
thunderstorm into this evening and through the overnight hours ahead
of Hurricane Newton. Periods of rain will then continue into
Wednesday night with areas of flooding possible. Storm total
rainfall of 1-3 inches is possible in the valleys with amounts in
excess of 4 inches in the mountains. Strong winds of 20 to 30 mph
with gusts to 40 mph will also be an issue Wednesday morning and
afternoon, especially near the Int`l Border. Lingering moisture will
result in a slight chance of showers and thunderstorms Friday into
Sunday, with 20-ft winds returning to their normal diurnal trends.
&&
DISCUSSION...A strong moisture increase will see a marked increase
in showers and thunderstorms this afternoon with strong outflows
and possible dust an issue. Brief heavy rain possible, especially
in the mountains. Focus for now is on areas near to south of
Tucson. We will probably see a break between this convection and
the onset of main influences from Newton.
As far as Newton, the table is set. Things have to happen just right
to have impact from a tropical system in southern Arizona, and all
analysis and model trends continue to point in the right direction.
The trough to our west and northwest is holding position just long
enough to finish guiding Newton into far northwest Sonora just south
of the border, and then looks like it gets out of the way to allow
Newton in instead of shearing the bulk of the remnants into New
Mexico.
One of the advantages that Newton has is it`s forward speed. There a
chance that he could reach the border as a minimal tropical storm
with sustained winds of 39 mph or a little higher. We are issuing a
wind advisory to address this issue, and will be watching trends to
make sure that will cover things.
The update also covered some timing issues, increasing the onset of
heavy precip by 3 or 4 hours with prime time looking like 06z to 21z
Wednesday for most of our area. QPF values are also increasing as we
gain higher confidence in the track. 1 to 3 inch rainfall amounts in
valleys with isolated amounts near 4 are possible. Some mountain
locations, especially closer to the border, could see up to 5
inches. The area that we are currently most concerned about is Santa
Cruz county, however it`s looking more and more likely that there
will be plenty of heavy rainfall potential for other areas as well.
The bottom line is Hurricane Newton is holding course and speed with
solid agreement between operational forecast models as well as most
tropical models. A quick look at 12z guidance including the UofA WRF-
NAM and latest HRRR is inspiring increasing confidence in
the forecast.
CLIMATE...The lowest maximum daytime temperature on record for
Tucson International Airport on Wednesday, September 7, is 77
degrees set in 1919. The maximum recorded rainfall for Tucson
International Airport on Wednesday, September 7, is 1.15 inches set
in 2006.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Wednesday evening for AZZ502>515.
High Wind Watch from 5 AM to 5 PM Wednesday afternoon for AZZ513.
Wind Advisory from 5 AM to 5 PM MST Wednesday for AZZ503-504-507-
508-512-514-515.
&&
$$
Meyer/French/Leins
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Cleveland OH
457 AM EDT WED SEP 7 2016
.SYNOPSIS...
High pressure across the area will begin to weaken and allow for
the advancement low pressure and a cold front across the area on
Thursday. A warm front will push north Friday evening which will
be followed by the cold frontal passage on Saturday. Cooler high
pressure will build in overhead for Sunday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Apex of upper ridge over the area will begin to break down as
minor shortwave energy rounds the ridge today. Not entirely sure
how today will turn out...but it will be hot and humid. Considered
a Heat Advisory for Toledo area and counties west of I-71.
Heat index values get real close to 100 degrees with current
forecast of temperatures and dew points...which is marginal for a
headline. If that forecast does not pan out and we really will
top out above 100 for heat index then a short notice heat advisory
would be needed. Will continue to highlight in the Hazardous
Weather Outlook.
Convection from last night across Wisconsin and Michigan laid out
an outflow boundary which the HRRR uses to generate new
convection early this morning. This is possible to some degree.
Overnight low level jet will be nudging eastward before morning so
some precipitation development not out of the question. Therefore
have a 20 percent chance first thing this morning for northwest
OH. Less focus for the afternoon...but enough instability and only
a marginal cap could still allow for a few more storms to pop this
afternoon. Shortwave energy may spark a few shower/storms across
far northeast OH/nw PA as that rounds the ridge. All in all 20-30
percent chances.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
By late evening convection should be coming to an
end...temporarily with the loss of daytime heating. It will remain
warm and muggy tonight.
Pattern will continue it shift through the end of the week as jet
energy and shortwaves work to keep a moderately amplified pattern
progressive. One shortwave to move across the Great Lakes late
tonight into Thursday will develop and take surface low pressure
across the central lakes and into Ontario. This will bring a cold
front across the area on Thursday. A few marginally severe storms
could result across the eastern portion of the area. Highs will be
held in check by cloud cover.
High pressure will briefly be in place on Friday. Big range in
guidance temperatures. Went with the warmer temperatures. The
front should clear our southern counties by morning and with no
real airmass change behind the front...80+ is likely. A slower
solution for precip return with the warm front will also help
temps.
Front lifts back north Friday night as an active warm front. Have
continued the likely precip chances. Precipitable water values
remain high through the cold frontal passage on Saturday
night...therefore locally heavy rain a real possibility.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
The long term forecast period begins on Sunday with the models being
consistent with the area being on the back side of an upper level
trough and high pressure building in from the west. This suggests a
dry pattern to start next week. With a cold front having gone
through the region Saturday, temperatures will be much cooler with
below average highs in the lower 70s which will be some much
needed relief from the heat. Long term guidance remains consistent
on a zonal pattern of sorts that settles in late Sunday through
Tuesday. Surface high pressure will remain through Tuesday
afternoon keeping the area dry and temperatures will come back up
to normal for Monday and then back above normal for Tuesday.
Beginning Tuesday afternoon through the rest of the extended
forecast, the models are considerably different with timing of the
next system. The GFS is much faster with an upper level trough
eroding the zonal pattern by Tuesday afternoon and extending a cold
front across the area. This would bring rain chances to the area
Tuesday afternoon to Wednesday afternoon. The ECMWF is about a day
slower with this upper trough and cold front and suggests rain
chances for most of Wednesday and the early part of Thursday. For
now, just hedged the precipitation chances with a slight chance to
chance pops from Tuesday afternoon to Wednesday night. Temperatures
look to return to normal for Wednesday but could become chilly
Wednesday night with lower 50s possible behind the cold front
regardless of which solution is correct.
&&
.AVIATION /06Z Wednesday THROUGH Sunday/...
For the most part, the TAFs remain relatively unchanged with this
package. High pressure over the eastern United States has drifted
southward a bit towards the central Appalachians. This will allow
a system to approach from the northwest on Wednesday into
Thursday. To start, things will be dry. Some MVFR vsbys are
possible as air mass has moistened with dew points in the upper
60s to lower 70s and a morning inversion will be in place, but
confidence is low as ground is dry with no recent rains and models
have been overdoing fog recently. In addition, convection over the
Lake Michigan basin is stretching eastward and has dispersed an
outflow boundary that will approach KTOL and KFDY just before dawn
which could hinder fog chances. Given all this, left tempos in but
those may be overdone.
As system approaches from the northwest, precipitation chances
will be on the increase Wednesday afternoon. The problem is that
there really is no trigger to get convection going and a mechanism to
have a reasonably confident forecast around so...have left the
TAFs dry for now but acknowledge that someone may see a shower or
a rumble of thunder tomorrow but have no confidence in when or
which site.
OUTLOOK...Periodic non-VFR possible Thursday through Saturday.
&&
.MARINE...
Lake conditions will be alright for Wednesday as southwest winds 5
to 15 knots and waves 1 to 3 feet as high pressure shifts southeast
and a new system moves in from the west. With this new system, a
cold front will approach from the west and winds will increase ahead
of the cold front to 15 to 20 knots out of the southwest and will
remain through early Friday. A small craft advisory may be needed
for Thursday afternoon through early Friday as conditions could
develop as wave will be on the increase as well.
Winds will diminish to 10 knots or less from the south as a warm
front then looks to move through the area on Friday night and then
another cold front will move through the area on Saturday night.
Winds will be on the increase again back to 15 to 20 knots from the
southwest Saturday into Saturday night. Small craft advisory
conditions may develop again with this cold front on Saturday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Oudeman
NEAR TERM...Oudeman
SHORT TERM...Oudeman
LONG TERM...Sefcovic
AVIATION...Sefcovic
MARINE...Sefcovic
Area Forecast Discussion
National Weather Service State College PA
600 AM EDT WED SEP 7 2016
.SYNOPSIS...
Hermine will linger off the coast today. The strong ridge aloft
over the MS/OH valleys will weaken a bit as storms break over the
ridge. Muggy air will stick around until a cold front passes
through this weekend. After a day or two of seasonable
temperatures Sunday and Monday another warm-up will occur.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Showers blossomed around 3 AM and have become quite numerous over
the Laurels and Alleghenies. It has to be elevated convection, but
it is odd to see things flare up in the middle of the night
without a strong LLJet. They heat/moisture are increasing slowly,
and there is some sort of front/convergence going on overhead. Some
training is seen in the SSE movement of the cells. However, the
cell movement is rather quick and any heavy rain will be spotty.
No lightning at all with these showers as tops of the clouds are
just not cold enough to generate ice. Showers seem like they are
rather steady-state but do also seem to be re-generating upstream.
Therefore, high confidence leads to big uptick in POPs with the
most recent grid updates.
ALL of the near-term models have almost no clue this stuff
exists. Quite troubling that the HRRR and RAP are doing so poorly
at initializing this convection, especially since it is pretty
widespread here at 6 AM, and has been on-going for at least 3
hours. The SREF mean qpf and derived POPs are doing rather well,
only it places things 50-100sm too far to the west.
Prev...
Muggy air into western PA and it is trying to slide into the CWA,
but is not headed directly at us - more to the north than east. In
contrast - dry air indicated by dewpoints in the 50s is being
reinforced over the eastern half of the state. The northerly flow
from Hermine is likely drawing some dry air in from the north and
large-scale subsidence over the region can only help to dry
the low level air out. The CWA seems to be in the doldrums at
this point. There has been an interesting N-S line of radar
returns has been sliding to the west over the last few hours. This
may be the leading edge of slightly drier air. In the convergence
to the west of that line there have been some showers pop up in
the south- central mountains. Should be fun to watch the effect,
if any, that line has on the stability of that marginally unstable
airmass. It is certainly odd to see things popping up in the
nighttime stability in central PA, so it is most likely not
surface-based convection. Cloud bases are 5-6kft.
The stability of the atmosphere is the part to the forecast which
is most challenging and exciting today. Hints from SPC and model
output from 00z show a higher possibility for shra/tsra for later
today than has been indicated over the past few days. This may be
thanks to the convergence as the higher PWAT air bumps in from the
WSW. Some support from short wave troughs/MCVs from convection
currently over the Upper Great Lakes could serve to fire up more
than just a few storms late this morning and especially this
afternoon and evening. CAPE eclipses 1000 before noon at UNV per
the NAM while the GFS is much more stable - probably because it
does show the very warm air aloft. Still, the GFS pops some
convection in the sub-1000 CAPE it generates a little later in the
day than the NAM does. The HRRR and RAP both look similar to the
NAM, with sfc-based CIN there as well. So, that is two strikes
against deep convection - warm temps aloft and sfc-CIN. However,
our mountain-supplied lift and the moist-warm air advection can
overcome the low level stability-problem. Have bumped POPs into
the high chance to low likely range for the central mountains/Susq
Valley this afternoon. New SPC Day1 outlook should be out very
shortly, but we are currently in MRGL risk for Day2 S & E of UNV.
Seeing the short-term soundings, there is a possibility for a
strong storm or two. But, will hold off on any mentions of gusty
winds in the grids and just call them tsra for now.
If we can develop more showers, the temps will be held a little
cooler than prev fcsts have indicated. Will temper them just
slightly, allowing for internal consistency with more clouds and
some showers anticipated. Some spots in the far SE could still get
to 90F.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Any on-going convection will likely linger past sunset and
continue it`s southward slide and be out of the CWA by midnight.
Fog is again possible, but more so where rain fell earlier, and
not contained to the typical river valleys. Clearing seems
possible in the SE after midnight, but other areas will continue
to have a parade of clouds moving down across the lower lakes
tonight. The higher dewpoints and clouds will probably keep it
uncomfortable tonight with mins 65-70F. Will just include an
isolated shra in the forecast after midnight for most/all of the
area.
Thursday should hold showers for the NW as a weak change/lowering
in dewpoints slides down from the NW. The sfc low is passing well
to the NW as it takes a track up Lower Ontario and just N of the
St Lawrence River. However, the juicy air and timing of the front
will cause shra/tsra - at least in the NW third of the area. With
mostly sunny skies in the SE on Thursday and 8H temps nearing
+20C, the maxes will likely get into the 90s - even the m90s are
possible (not likely) in the lower elevations/urban areas. The
Heat Index will probably be in the u90s in the afternoon.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Hermine will meander over the Gulf Stream for the next couple of
days with the latest 12Z guidance agreeing that it will likely
take until late Thursday or early Friday before it finally begins
moving up off the Cape Cod coastal waters.
Active northern branch of the jet stream is forecast to send
multiple shortwaves eastward across the northern tier of the
CONUS...bringing an increase in the chances for
showers/thunderstorms for late in the week.
A stronger mid level trof/surface cold front is advertised for
later Saturday with Sunday bringing the hiest chances of pcpn
during the period. Behind the front, it will turning slightly
cooler and noticeably drier into early next week.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
09Z TAFS sent.
BFD got some fog.
The interesting thing is the showers that formed on the
convergence line across the western part of the state.
Expect these to move out of the area soon, but more
will be possible late. Still think bulk of the day
will be dry with VFR conditions.
Outlook...
Thu...Patchy AM fog possible. Isold PM tsra impacts possible,
mainly nw Mtns.
Fri...AM low cigs possible w mtns.
Sat...Isold PM tsra impacts possible, mainly w mtns.
Sun...AM log cigs possible w mtns.
&&
.CLIMATE...
Records today: IPT=95 and MDT=96.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...La Corte/Gartner
AVIATION...Fitzgerald/Martin
CLIMATE...
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
315 AM EDT WED SEP 7 2016
.DISCUSSION...
Very warm and humid airmass remains firmly in place this morning as
indicated by temperatures in the mid to upper 70s and dewpoints
solidly in the low 70s in most areas. Warm/moist southwest flow will
persist through Thursday as the longwave pattern flattens, but
remains largely unchanged over the Great Lakes. The deep trough over
the western US will not progress through the area, but will rather
decrease in amplitude and lift northeast around the subtropical
ridge, flattening it as it does so. As this happens, shortwaves
emanating out of the weakening trough will provide opportunities for
precipitation.
Showers are ongoing this morning along the low-level jet axis and
beneath a region of favorable jet support, mainly over Wisconsin and
Lake Michigan, but also weakly leaking into western Lower MI.
Showers have struggled to make it into Southeast Michigan, but may
find some success before sunrise as the LLJ axis gradually works
east before weakening during the morning. For this, just a chc pop
remains in place for the early morning hours.
High dewpoints, temperatures around 90 degrees, and advection of
steeper lapse rates aloft will likely result in moderate
destabilization by this afternoon. RAP ML CAPE is progged to reach
at least 1500 j/kg. At the same time, mid-level capping is notably
weaker than yesterday, and a developing surface low over the Upper
MS Valley will aid in a strengthening, but still modest (20+kts)
westerly LLJ nosing into the area during the afternoon. No qualms
with guidance such as the HRRR which indicates scattered t-storm
development getting under way in the 19-20z time window. Effective
shear will be quite weak, but a few strong wind gusts of 40 to 50
mph cannot be ruled out, especially with the mean flow behind any
cells that do develop. Heavy downpours a good bet with PWATs up
around 2 inches. High chc pops for this afternoon appropriate for
now, but concerns with regard to coverage and location preclude
going likely. Barring convective development occuring too early in
the day, heat indices are likely to reach 100 degrees in Detroit and
the surrounding urban corridor. A heat advisory has therefore been
issued for the far SE counties.
Dynamic forcing will increase markedly tonight, mainly from the
Saginaw Valley north, where a surface low will track between 00z and
12z Thursday. Categorical pops confined mainly to the waters of Lake
Huron and the immediate Saginaw Valley area. From I-69 south, it
will once again be a case of a rather ill-defined forcing field
mainly focused along the tail end of the LLJ/moisture transport
axis. Envision a scenario in which a slug of rain lifts across
Northern Lower while a corridor of trailing showers settles south
over the CWA, gradually dissipating with time. POPs therefore range
from categorical in the north to just 30 pops near the Ohio border.
Passage of tonight`s wave will sufficiently suppress the mid-level
thermal ridge to bring lower, but still warm, temperatures in the
mid 80s on Thursday. Surface moisture will remain in place, however,
ensuring another humid day and heat indices near 90 in the Detroit
Metro area.
Focus for the end of the week turns to the evolution of a strong
corridor of jet energy immediately south of the Aleutian Islands and
subsequent interaction with the remnants of Hurricane Newton,
presently located in the Gulf of California. NWP consensus exists on
a chunk of the remnant energy shearing northeast into SE Michigan
Friday night in advance of the rapidly deepening trough. Strong
isentropic ascent and moisture transport will likely result in a
corridor of moderate rainfall overnight Friday. Although NWP are
struggling with the exact nature of the interaction, a swath of rain
lifting through MI still appears probable. No changes to blended
grids at this time.
&&
.MARINE...
A weak frontal boundary will settle into Lake Huron today and
produce light and variable wind while maintaining modest southerly
wind over other marine areas. Wave response will be minor in this
pattern outside of thunderstorms which will be the most impactful
weather element in the forecast today through tonight. A ripple of
stronger low pressure is expected to move along the front tonight,
exit eastward into Thursday morning, and then pull the front through
the region. Light to moderate northwest to west wind will occur post
front through Thursday before weak high pressure arrives Thursday
night into Friday.
&&
.HYDROLOGY...
Warm and humid air will continue to stream into SE Michigan today
ahead of a cold front located over the northern Great Lakes and
Midwest. Scattered thunderstorms will be possible mainly during the
mid afternoon into evening, and with greater coverage in the Tri
Cities and northern Thumb region. This activity will be capable of
localized rainfall in the 0.5 to 1 inch range over small areas.
Another round of more numerous showers and thunderstorms will
develop during the day along the cold front to our west. This
activity is expected to move into SE Michigan during the night,
mainly after midnight through mid Thursday morning. Coverage will
again be greater in the Tri Cities and northern Thumb down to about
the I-69 corridor with a weakening trend expected to the south
toward the Ohio border. Rainfall potential will also remain in the
0.5 to 1 inch range but with greater coverage than during the day.
Isolated totals in excess of 1 inch will also be possible and could
lead to minor urban and small stream flooding.
Another larger low pressure system is projected to arrive in the
Great Lakes Friday night. This system is setting up to affect the
area with similar rainfall potential in showers and thunderstorms
Friday night through much of Saturday.
&&
.PREV DISCUSSION...
Issued at 1151 PM EDT Tue SEP 6 2016
AVIATION...
Area of showers and thunderstorms stretching from Lower Michigan
back through Wisconsin will be maintained in at least a scattered
form over Southeast Michigan by steep low-level lapse rates, a
nocturnal low-level jet, and additional moisture advection up into
Michigan. Some uncertainty as to how well it will hold together
however as Southeast Michigan remains more under the influence of
upper ridging centered over the Southern U.S., providing a layer of
warmer air in the mid-levels that is not present to our north and
west. Showers and possibly a few thunderstorms look to mainly have
an impact on FNT and MBS, but could also brush PTK. Other concern
for late tonight will be potential development of BR. The potential
for this will be lessened if we do see any organized area of
showers/tstorms affect any of the terminals. Slight southwest
gradient should however keep restrictions limited to MVFR.
Renewed chances for showers and thunderstorms will exist on
Wednesday, especially by late afternoon and evening as heat/humidity
build and as cooling in the mid-levels helps to destabilize the
atmosphere.
For DTW...
//DTW Threshold Probabilities...Area of showers and thunderstorm
stretching from Central Michigan back through Wisconsin will likely
remain north of DTW. Mostly clear skies will bring potential for BR
development late tonight, but light southwest gradient should keep
visibilities at MVFR. Uncertainty surrounding thunderstorm
development in the DTW airspace tomorrow is high given only weak
forcing in a hot and unstable atmosphere, but best potential will be
during the afternoon and evening.
* Low for ceiling 5000 ft or less tonight. Moderate tomorrow
afternoon.
* Low for thunderstorms until late tomorrow afternoon and evening.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Heat Advisory from noon today to 8 PM EDT this evening FOR MIZ069-
070-075-076-082-083.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
DISCUSSION...JVC
MARINE.......BT
HYDROLOGY....BT
AVIATION.....HLO
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Grand Forks ND
340 AM CDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
Issued at 340 AM CDT Wed Sep 7 2016
Convection timing and strength this afternoon and tonight will be
the main forecast problem for the period.
High pressure remains over much of the forecast area and dew
points are still in the upper 40s and 50s as of 2 AM CDT. However,
better moisture with 60s dew points is just to our southern
border, and surface winds will shift around to the southeast
throughout the morning. The upper trough currently over MT is
progressing rapidly to the east, and should move into the Western
Plains by late afternoon. This will help push the surface trough
axis currently over eastern MT/WY eastward and into the western
CWA by late afternoon. While temps may be limited a bit by
increasing clouds, still think we should get into the upper 60s to
low 70s across the southwestern counties. This should help
instability get up to around 1500 J/kg by this afternoon. While
this is not insanely high, there will be 50 kts of deep layer bulk
shear and upper support will be good for storm development. The
NSSL WRF and HRRR both bring some fairly significant storms into
our southern counties by 20Z or so. The WRF runs show mostly
convection in a linear bow, but with the low level wind profile
bringing some nicely curved hodographs there will be a threat of
tornadoes possible at least in our southern counties.
The system will be quickly moving, with the surface low moving
into MN by early evening and off to the east of our counties after
midnight. The NAM puts out some high QPF values in a similar track
over areas that received heavy rain Sunday night. However the
other global models are further south with the heaviest rain. In
addition, with the quick movement of the system think that unless
we get cells training over each other that flooding will not be
too much of a problem. Rain should end from west to east during
the night with only a few lingering showers near Lake of the Woods
by early Thursday morning. Lows will be mostly in the 50s.
.LONG TERM...(Thursday through Tuesday)
Issued at 340 AM CDT Wed Sep 7 2016
Thursday through Friday...Southwesterly flow aloft continues with
several decent shortwave troughs moving through. Think that most
of the day on Thursday should be fairly quiet, but one of the
shortwaves will help push a surface trough into the Red River
Valley Thursday night. Moisture recovery will not be as good and
much of the upper support will be to our south or north so kept
POPs a bit lower in the 20-40 percent range. The surface low will
move east during the day on Friday but the main upper trough will
still be pushing through and models are indicating some signs of
mid level frontogenesis behind the surface boundary. Will keep
chance POPs going for Friday and then taper them off Friday night
as the upper trough digs into the Upper Mississippi Valley. Temps
should be near seasonal averages on Thursday in the upper 60s to
mid 70s but a bit cooler for Friday.
For Saturday...upper level trof shifts over the area in the wake of
a cold front. Thus...expect cooler temperatures across the region to
start the weekend. Precipitation ends as surface high pressure
builds in...allowing for more pleasant conditions along with light
winds.
By Sunday night into Tuesday...the pattern continues to be
progressive as an upper level ridge shifts across the northern
plains. Surface high pressure retreats to the east allowing return
of southerly flow. Therefore...will see warmer temperatures
spreading across the region ahead of another system...and increased
chances of showers or storms for the Monday time frame.
Otherwise...cooler and more tranquil weather is expected to end the
period.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1127 PM CDT Tue Sep 6 2016
Timing from the previous set of TAFs still looked pretty good.
Tstms should arrive in the KDVL area first by late afternoon, then
spread eastward into the other TAF sites. Kept about a 4 hour
window for tstm duration, but it could very well be shorter than
that too. Tried to provide the best idea for when the storms may
affect each TAF site, as storms are the main aviation challenge.
Later shifts can lower vsbys or ceilings if models trend that way.
&&
.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&
$$
SHORT TERM...JR
LONG TERM...JR/Hopkins
AVIATION...Godon
Area Forecast Discussion
National Weather Service Hastings NE
440 AM CDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
Issued at 407 AM CDT Wed Sep 7 2016
Aloft: SW flow remained over the Cntrl Plains...with a
subtropical high over the lwr MS Valley and a broad deamplifying
trof over the Wrn USA. Multiple embedded shortwave trofs will
knock down the ridge over the Ern USA...carving out a broad trof
over the Nrn 1/2 of the CONUS by daybreak Thu. The remnants of
Newton will lift into AZ today. The leading edge of its mid-lvl
circulation will get sheared to the NE and make it into SW KS by
Thu morning.
Surface: An elongated front extended from UT/CO across the Cntrl
Plains to the Great Lakes. This front was just S and E of the fcst
area...extending from W-cntrl KS into SE Neb. This front will
remain quasi-stationary today...but as heights fall downstream the
front will get nudged a little further S and E of the fcst area
tonight... with a small high building over Neb.
Overnight...once again the beneficial rain fell in areas that did
not need it (N-cntrl KS) and did not fall in areas that
desperately need it (nearly all of S-cntrl Neb). A mesonet site
near Palco (Rooks County KS) measured 3.13 in 6 hrs. Please see
hydro section below.
Now thru sunrise: the dissipating remnants of earlier tstm
activity will cont to move NE and exit the fcst area. While the
main low-lvl jet axis is veering toward IA/MO...rgnl 88D wind data
suggest 20-35 kts is still aimed toward the fcst area with speed
convergence implied. The 07Z HRRR suggests more shwrs could
develop. With the atms overturned by earlier convection...it`s
doubtful enough instability exists for thunder...although an
isolated strike or two can`t be completely ruled out.
We also will be monitoring for patchy fog. Dwpt depressions are
small (2-3F) and winds are light. Any radiating will result in
fog. Just not sure how bad or widespread it could be.
Cloud cover: There is an expansive shield of multi-layered mid-
high clouds streaming into the region ahead of Newton (now ovr the
Gulf of CA). While some of this could thin at times...overall
believe skies will be m/cloudy thru tonight. The NAM shows these
high clouds are on the higher tropopause and heights will not
begin to fall (shoving the cloudband SE) until late tonight...as a
shortwave trof heads into the Dakota`s.
Today: Possibly a few shwrs this morning. Otherwise
m/cloudy...with temporary improvement to p/cloudy at times. Can`t
completely rule out an isolated tstm this afternoon E of Hwy 281.
But most locations will be dry today.
Tonight: Possibly an isolated tstms on the extreme E fringe of
the fcst area. Otherwise dry under m/cloudy skies.
Not expecting any strong/severe storms and this agrees with SPC
risk of just general tstms.
.LONG TERM...(Thursday through Tuesday)
Issued at 439 AM CDT Wed Sep 7 2016
Thursday and Thursday night are a bit murky and confidence is low
here. With a stalled out boundary nearby or to the south and
increasing warm air advection, we could have some nocturnal
convection erupt. However, there is a lot of discrepancy in the
model world, and I wouldn`t hang my hat on getting precip. However,
if storms develop, mid-level lapse rates should be steep enough for
some strong to severe thunderstorms. It`s a tough call on where the
front will be, and if it lies in our southeastern CWA like I expect
it might, we could be in for some fog near the boundary.
For Friday, we could get some firing of thunderstorms east/southeast
along the cold front, and we finally get a solid push from a mid-
level trough that will clear the front from our area for awhile.
On Saturday, we will be to the west of a departing wave, so I expect
dry weather through Sunday night with general subsidence.
The next trough heads south into the western United States on
Monday, helping to push a a strong cold front through, which will
lower temperatures and dewpoints noticeably. Multiple impulses of
energy may be repeatedly sent into the central Plains thereafter in
the post-frontal regime, giving us the potential for a number of
relatively cloudy, cool, and damp days next week with highs only in
the 60s for Tuesday and a few days thereafter.
&&
.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Thursday)
Issued at 1259 AM CDT Wed Sep 7 2016
Significant Wx: IFR CIGs cont thru 14Z. MVFR VSBYs possible in fog
toward dawn.
Overnight: Confidence is high in IFR CIGs...but low on potential
for MVFR fog to develop after 08Z. Some -RA will be around with
the possibility of a brief heavier shwr with MVFR or IFR vsby.
Light NNE winds under 10 kts. Confidence: Medium
Wed: IFR stratus CIGs to start with possible MVFR fog...gradually
lifting to MVFR CIGs by 15Z and then VFR CU around 4K ft by 19Z.
Light SE winds will gradually become SW. Confidence: Medium
Wed eve: VFR cirrostratus CIGs around 20K ft. Light SW winds
become NW. Confidence: High
&&
.HYDROLOGY...
Issued at 407 AM CDT Wed Sep 7 2016
Another area of R+ occurred upstream of Phillips/Rooks/Osborne
counties. Ground truth is limited...but MRMS 12 hr radar estimates
are very close to the 2.66" that fell at HLC and the 3.13" that
fell near Palco. So confidence is high that the swath of MRMS
estimates of 4-7" is legit. Some of this will be running off into
Wildhorse and Lost Creeks...and ultimately into the S Fork of the
Solomon Rvr. We are already seeing the initial response in Damar
and Woodston.
In anticipation of renewed rises on area creeks and rvrs...we
issued a Flood Watch last eve at 1134 pm and it conts as posted
thru 6 pm today. This Watch may need to be extended. In coord
with the Rvr Fcst Ctr...we are expecting creeks and rvrs that fell
below flood stage to rise and flood again. Please follow Flood
Statements and possibly additional Warnings from this office.
It appears we do have a break coming with no heavy rainfall
expected for svrl days. This should allow creeks/rvrs to process
the run-off and then drop below flood stage and remain within
their banks for a while.
&&
.GID Watches/Warnings/Advisories...
NE...None.
KS...Flood Watch through this afternoon for KSZ005-017-018.
&&
$$
SHORT TERM...Kelley
LONG TERM...Heinlein
AVIATION...Kelley
HYDROLOGY...Kelley
Area Forecast Discussion
National Weather Service Goodland KS
333 AM MDT WED SEP 7 2016
.SHORT TERM...(Today through Friday night)
Issued at 332 AM MDT Wed Sep 7 2016
Early morning WV imagery and RAP upper level analysis shows SW flow
in place across the plains ahead of large scale upper trough over
the western US. Severe shortwave troughs are progressing through the
mean flow with one over eastern Nebraska and another in southeast
Colorado. At the surface a stalled front extends across our southern
CWA with a low pressure centered over southeast Colorado.
This morning: Stratus/fog have developed across the northwestern
part of our CWA, and vis has briefly dropped to 1/4 to 1/2 miles at
a few locations. Confidence is low that this would prevail or be
widespread and visibilities have fluctuating a lot in these areas.
Will continue to monitor for more persistence in dense fog coverage,
but for now I am not anticipating a dense fog advisory (continuing
to handle with Special Weather Statement).
Today-Thursday: Air mass aloft changes very little, and with good
available moisture and moderate instability there is a potential for
thunderstorms through these periods. Confidence is lower as better
large scale forcing will be shifted to our southeast, and models
show little in the way of initiation. With stalled front nearby I
can`t rule out thunderstorms late this afternoon and overnight,
however better chances still appear to be Thursday afternoon/evening
as the remnants of Hurricane Newton move through the southern
plains. Even then there is not a lot of confidence and we may
actually see larger Td depression spreads through a deep layer of
the atmosphere (as shown by GFS) which would possibly limit coverage
(if something were to initiate. I didn`t make major changes to
ongoing PoPs forecast, favoring model blend/consensus. Temperatures
are generally going to be near seasonal levels, though this could be
dependent on cloud cover and clearing. With better clearing daytime
temps could be closer to 90F and overnight lows below 60F.
Friday-Friday night: A shortwave trough moves across the Northern
Plains and kicks a cold front south over our CWA. With deeper dry
layer in place and better forcing north of our CWA, the main impact
on sensible weather should be on temperatures. Below normal highs
and lows are expected with many locations in the 70s on Friday.
Chilly temperatures in the 40s will be favored for most locations,
and I could see a few low spots in the west possibly drop to the
upper 30s (based on dryness of BL).
.LONG TERM...(Thursday through Tuesday)
Issued at 223 AM MDT Wed Sep 7 2016
The general pattern for the extended period starts with dry weather
and gradual warming conditions over the weekend followed by chance
of storms returning to the area beginning of the week and
lasting through the rest of the period.
High pressure will build over the region behind a strong cold front,
that will pass through the area on Friday. The air behind this front
looks to be cool and dry. This will produce mostly clear skies and
light winds for the weekend. The high temperatures will reach the
upper 70s on Saturday and upper 80s on Sunday. Overnight temps will
drop into the mid 50s.
At the start of the week the models are showing another front
passing through the Tri-State area and producing chance of storms
from Monday through the end of the period (Wednesday). At this time
confidence is to low. So I will wait until tomorrow night`s run to
expand on the details.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1112 PM MDT Tue Sep 6 2016
Aviation concern for the rest of tonight will be chances for low
clouds and fog. Showers/thunderstorms continue to push east and
not expected to impact either KGLD or KMCK. Cold front has sagged
into northwest Kansas, putting both terminals on the cool/light
upslope side where low clouds and areas of fog will develop before
sunrise and slowly dissipate through mid morning. Should return to
VFR by late morning or at worst early afternoon, with VFR for the
remainder of the period.
&&
.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BW
AVIATION...024
Area Forecast Discussion
National Weather Service Lincoln IL
321 AM CDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 321 AM CDT Wed Sep 7 2016
07z/2am surface analysis shows high pressure over Tennessee, while
slow-moving cold front remains draped further northwest from the
Upper Peninsula of Michigan southwestward to Nebraska. Widespread
convection has developed along this boundary, with a few isolated
showers further south across portions of central/eastern Iowa. HRRR
has consistently shown these showers developing/spreading further
east into north-central Illinois this morning. As a result, have
carried slight chance PoPs north of the Peoria area. Further south
across the remainder of the KILX CWA, another very warm and humid
day is on tap. Southwesterly winds gusting to between 20 and 25 mph
at times will continue to transport high dewpoint air into the
region. Afternoon high temperatures will once again reach the lower
90s, while heat index readings range from 100 to 105 degrees. While
synoptic forcing will be absent, a few of the high-res models such
as the WRF-ARW and HRRR suggest isolated convection may develop
across the E/SE during peak heating. Since this has happened the
past two days, decided to mention isolated thunder east of I-57
this afternoon.
As a short-wave trough currently evident on water vapor imagery over
the Northern Rockies tracks eastward and begins to flatten the
prevailing upper ridge over the Midwest, it will push the cold front
toward Illinois tonight. Numerous showers and thunderstorms will
develop along/ahead of the front within the very moist airmass
characterized by precipitable water values in excess of 2 inches.
While 0-6km bulk shear will initially be quite weak, it will
increase to 30-35kt along/north of a Rushville to Bloomington line
this evening. This suggests the potential for some organized
thunderstorms capable of gusty winds and locally heavy rainfall.
Have carried likely PoPs across this area this evening accordingly.
As the front sinks slowly southward, rain chances will spread
across all but the far SE CWA after midnight.
&&
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 321 AM CDT Wed Sep 7 2016
As was first seen with the 00z Sep 6 models, the latest model suite
shows the cold front settling southward into central Illinois on
Thursday as a weak area of high pressure builds into Iowa/northern
Illinois. As a result of this southward push, have ended rain
chances across the northern CWA Thursday afternoon. The boundary is
still expected to stall late in the day, with a weak wave of low
pressure developing and tracking along it Thursday night into
Friday. Models are still not in perfect agreement here: however,
general consensus focuses best rain chances across the southern half
of the area. Have therefore gone with likely PoPs along and south
of I-72 on Friday, with chance PoPs further north.
A stronger short-wave trough is progged to track across the Plains
Friday night, giving the persistent frontal boundary a solid push
eastward. Given increasing synoptic lift associated with the
approaching wave and ample deep-layer moisture, likely PoPs are
warranted across the board Friday night. The front still appears to
sweep through the region fairly quickly on Saturday, with the GFS
being the slowest model. Have maintained chance PoPs across the
east through Saturday morning, then gone dry everywhere by
afternoon. Main weather story this weekend will be the cooler and
drier conditions, as high temperatures drop into the 70s for both
Saturday and Sunday. After that, the next significant chance for
rain will hold off until next Tuesday at the earliest.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1150 PM CDT Tue Sep 6 2016
VFR conditions will prevail at all TAF sites next 24hrs. Skies are
clear at all sites and should remain that way at most sites
overnight. Satellite loops showing some mid clouds possibly
advecting toward PIA late tonight and HiRes models forecasting
some increasing mid level moisture around 10-11z in that area, so
have added some scattered mid clouds around 7kft late night/early
morning. Then all sites should see scattered CU develop for the
day, like on Tue. PIA will be closer to the approaching front and
believe CU will remain and thicken during the evening hours.
Convection could be moving into the area, but timing is uncertain
at this time. So will just have VCTS at PIA starting at 02z. All
other sites will see scattered CU continue as well at a higher
level as well but will have broken AC at SPI and BMI and broken CI
at DEC and CMI. Winds will be southwest through the period with
little stronger during the day, with speeds of 14-15kts.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten
Area Forecast Discussion
National Weather Service Jackson MS
400 AM CDT WED SEP 7 2016
.SHORT TERM...Today through Thursday night...Water vapor imagery
this morning showing much drier air working its way into the forecast
area from the east. Total precipitable water imagery in agreement
with the RAP with PWs less than 1.5 inches already into the eastern
half of the area. The dry airmass will continue to slowly progress
westward in the short term, but PWs greater than 1.5 inches look to
hold on in the west today and the far west on Thursday. This should
result in isolated shower and thunderstorm development in the heat of
each afternoon.
The dry airmass will promote more efficient heating and deeper
mixing in the east today and Thursday. This will make the mid 90s
attainable over a large area. Conversely tonight and Thursday night,
the dry air will support better radiative heat loss and the
potential for minimums as low as the mid 60s./26/
.LONG TERM...Friday through Wednesday...The effects of the upper-
level ridge will still be felt across the ArkLaMiss on Friday, with
subsidence keeping drier air across the area and rain chances low.
Afternoon relative humidity values could drop to between 35 to 45
percent for most locations. Then model guidance shows good agreement
for the ridge to break down over the weekend and into early next
week as a shortwave trough slides across the northern CONUS.
Meanwhile a developing surface low near the Great Lakes will drag a
cold front into the southeastern U.S. as it pullls eastward. Have
trended a little more aggressive with the cold front for this
forecast, based on guidance which suggests the front could make it
into the forecast area late Saturday. Some question remains about
how far southward the front will make it, but think it should push
far enough to bring high temps to near normal on Sunday and min
temps down to the mid 60s for northern zones for Monday morning.
Areas closer to the coast will probably remain on the warmer and
more humid side as the front washes out across the Gulf Coast.
Primarily, the front should serve as a focus for potential
convection as it moves southward, so best POPs currently focused
along and south of the front where deeper moisture will be in place
each day. Model guidance tries to develop some semblance of a ridge
of high pressure across the southern CONUS again by the middle of
next week, with moist southerly flow returning to the lower levels
across the region. Have therefore kept slight chance POPs for
afternoon showers and thunderstorms through the extended period./NF/
&&
.AVIATION...MVFR visibilities in fog can be expected for the most
part this morning until 07/14Z. The exception will be at HBG where
IFR conditions in dense fog will persist until 07/14Z. Thereafter,
VFR conditions will prevail. Fog may become a problem again after
08/05Z at HBG./26/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 93 70 94 68 / 9 11 11 4
Meridian 95 67 95 67 / 2 7 7 0
Vicksburg 93 71 93 68 / 19 10 12 7
Hattiesburg 92 68 92 67 / 3 4 5 4
Natchez 91 71 91 68 / 24 3 8 5
Greenville 94 73 92 71 / 17 8 17 5
Greenwood 93 70 93 69 / 6 8 12 3
&&
.JAN Watches/Warnings/Advisories...
MS...None.
LA...None.
AR...None.
&&
$$
Area Forecast Discussion
National Weather Service North Platte NE
359 AM CDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
Issued at 358 AM CDT Wed Sep 7 2016
Early this morning stratus is developing over all of western
Nebraska with areas of fog starting to develop over the southeast
Nebraska panhandle and southwest Nebraska. Isolated thunderstorms
will continue through the early morning hours north of an Arthur
to Broken Bow line. Stronger wave exiting northeast Nebraska on a
120kt+ jet as seen in water vapor imagery. Lot of moisture
streaming across the southwest conus through western Nebraska.
Can see the remnants of hurricane over northern Mexico. Pwats
will be high today and some concern with cloud cover. Have come
to a compromise with surrounding offices. More cloud cover will
mean lower temperatures today and have gone with cooler guidance.
Have continued areas of fog though the morning mainly to the
west. Chances for thunderstorms ending over Holt county late this
afternoon. Highs today around 80 and lows tonight in the 40s
northwest and the 50s elsewhere.
.LONG TERM...(Thursday through Tuesday)
Issued at 358 AM CDT Wed Sep 7 2016
A mild day is expect on Thursday. A surface trough is expected
along the front range. Some concern model blended highs may be to
warm across the southeastern zones. Remnants of Newton expected to
track to the south although could see some high clouds wrap into
the CWA. Will continue to monitor as can not rule out a stray
storm but for now forecast mainly increased cloud cover.
Cold front expected Thursday night into Friday. Better moisture
across the eastern CWA and will keep pops in the forecast there.
Cool temps aloft for Friday and will have to monitor steep lapse
rates for increasing cloud cover. Then concerned shifts to Friday
night lows. Cool Canadian high pressure settles across the western
zones by Saturday morning. Guidance drops temps into the upper 30s
and lower 40s, which seems plausible given expected clear skies
and light winds. The GFS and EC most guidance for Alliance
Saturday morning are 35 and 36 degrees. This is the second week of
September and climatology says local frost is possible for the NW
zones. Not expected it to be that cold but will need to monitor
closely.
High shifts east with return flow to boost temps by Sunday into
the 80s. Short lived warm up with another push of cold air to
start the work week. Highs drop back into the 70s with lows in the
40s. A couple of disturbances could bring a chance for showers,
although not very confident at this time and will keep sporadic
pops low.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1141 PM CDT Tue Sep 6 2016
The RAP...ETA...SREF and MET guidance continue to show fog
forming tonight at KLBF and KVTN. The fog should be fairly
widespread the sandhills by 12z Wednesday. The models have sped
up the clearing process and VFR is expected by 21z Wednesday
across all areas. Flight conditions will improve from west to
east Wednesday morning. Confidence is moderate.
Thunderstorms are underway across scntl Neb. Additional rounds of
storms are expected overnight. The latest model consensus of
HRRR...ESRL HRRR and RAP models suggest areas along and south of
a line from KAIA to KTIF to KONL would experience scattered storm
coverage overnight.
Scattered storm activity could linger Wednesday morning across
Ncntl Neb but it is uncertain how long it would last Wednesday
afternoon.
&&
.LBF Watches/Warnings/Advisories...
None.
&&
$$
SHORT TERM...Power
LONG TERM...Masek
AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
527 AM EDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
Issued at 515 AM EDT WED SEP 7 2016
WV imagery and RAP analysis indicated wsw mid/upper level flow from
the cntrl plains through the wrn Great Lakes between a ridge over
the lower MS valley and a broad trough through the Rockies. At the
surface, a front extended from nrn lower Michigan through cntrl WI
to low pressure over wrn IA. A shortwave trough into ern Nebraska
along with upper level div from the right entrance of a 250-300 mb
jet from cntr Mn into nrn Ontario along with continued strong 850
moisture transport supported an area of tsra from nrn IA into sw and
cntrl WI near the frontal boundary. Other notable upstream
shortwaves were located over sw KS and cntrl Montana.
Today, expect the bulk of the shra/tsra to remain to the south of
the cwa as the convection remains closer to the surface front.
However, radar/satellite trends suggest that some of the pcpn
aided by the broad upper level div is trying to spread to the north.
So, the fcst maintained at least chance pops over Upper Michigan
that will gradually increase from the south to north through the
afternoon.
Tonight, there is uncertainty remaining with the impact of the KS
shortwave on the coverage/location/intensity of the tsra this
evening. There is the potential for some heavier rain in the 1 to 2
inch range over the far south, as a surface wave develops along the
front in response to the shrtwv moving through the region. The
heavier pcpn is expected to shift into the ern cwa by late evening
and overnight. Additional pcpn may devlop from wrn Lake Superior
into wrn Upper Michigan as a shrtwv from the nrn plains lifts
through nrn MN to nw Ontario.
.LONG TERM...(Thursday through Tuesday)
Issued at 526 AM EDT WED SEP 7 2016
Somewhat active zonal flow weather pattern setting up across the
northern CONUS for the end of this week into the middle of next
week.
Thu into early Fri...Models trending drier with Northern Plains
shortwave forecast to move across the region on Thu as associated
best q-vector convergence and deeper moisture generally tends to
stay well of north of Upper Mi into northern Ontario. Track of
shortwave and associated weak forcing would favor northwest Upper Mi
and northern Lake Superior for perhaps light rain in the morning.
Broad mid-upper level ridging and assoc Q-vector
divergence/subsidence in the wake of the shortwave Thu afternoon
will allow for a period of mostly dry weather Thu afternoon into
Friday morning.
Friday afternoon into Saturday...The forecast for this period looks
challenging at this time as model guidance appears split into
generally two camps. The 00Z GFS appears to have backed off from
deeper shortwave/sfc low solution advertised in last night`s runs
while the 00z ECMWF...Canadian and 06Z NAM models still hold on to
stronger and more phased solution developing a deeper sfc low over
northern Lake Mi/eastern Upper Mi Sat morning. Whichever of these
solutions pans out will have a large bearing on forecast. If the 00z
GFS solution pans out developing a weaker sfc low tracking just
southeast of Upper Mi, then the better chance for pcpn would be over
central and eastern counties of U.P. and the west would stay drier.
However, if the deeper and farther nw track of the 00z Canadian and
ECMWF/06z NAM solutions verify this would tend to bring more
widespread rain to the entire area Fri night and develop perhaps a
more defined deformation pcpn band into the western and north
central Upper Mi Sat morning on the nw quadrant of sfc low. Also if
850 temps of 6-7c get pulled across the lake per model guidance
could maybe even see a brief period of lake enhanced rain for
portions of the east half early in the afternoon. A this time will
lean toward deeper solution of 00Z ECMWF/Canadian and 06Z NAM blend
as it is a bit more consistent with 00z runs from last night
although not quite as strong with sfc low. With this stronger
solution depicted by the ECMWF/Canadian/NAM model blend, northwest
winds will get a bit gusty on Sat with tightening gradient behind
deepening sfc low. Models soundings and guidance would suggest the
potential for northwest wind gusts of 25 to maybe as high as 30 mph
across the nrn tier counties with perhaps even some higher gusts
over the eastern half of Lake Superior. Would not be shocked if
there was a period of gale force gusts over eastern Lake Superior
Sat afternoon into early evening.
Ridging and subsidence behind Saturday`s shortwave and
assoc cold frontal passage should result in drier/cooler weather Sat
night into much of Mon. There is plenty of model uncertainty with
timing of next series of shortwaves and their movement along
incoming frontal boundary for late Mon into Wed time frame so will
continue to utilize model consensus low chc pops for next Mon night
into Wed.
Temps should remain near or slightly above normal for Thu and Fri
but should then fall slightly below normal for the weekend in the
wake of the cold fropa Fri night. Dewpoints in the lower to mid 60s
will make it still feel humid on Thu, but then dewpoints should fall
back into the more comfortable 50s range for Fri into early next
week. Both the ECMWF and GFS advertise more fall-like temps for the
middle of the next with 850 mb temps of 2-4C advecting in from south
central Canada in nnw flow by Tue night into Wed time frame. Again
some light lake effect rain off Lake Superior might not be out of
question with this scenario.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 127 AM EDT WED SEP 7 2016
Confidence remains low for the fcst overnight as varying cloud cover
will impact radiation fog coverage and vis restriction. With some
influx of drier air on developing light ne winds, fog should be
least restrictive at KCMX where conditions should be MVFR overnight.
KIWD may see fluctuation btwn MVFR and IFR, but not out of the
question for VLIFR at times if clouds occasionally clear out. KSAW
should see VLIFR. MVFR cigs should then be the rule at KIWD/KCMX
today while KSAW may only improve to IFR. Shower chances should
increase late in the fcst periods as a disturbance approaches.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 515 AM EDT WED SEP 7 2016
Winds through tonight are expected to remain mainly at 20 kts or
less. The strongest winds will be Thursday and again on Saturday with
gusts up to 30 knots out of the west on Thursday and out of the north
and northwest on Sat as a deepening low pressure system lifts to the
e of Lake Superior. No gales are expected but cannot rule out gale
potential Saturday if the low pressure trends stronger.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Voss
AVIATION...JLB
MARINE...JLB
Area Forecast Discussion
National Weather Service Norman OK
348 AM CDT WED SEP 7 2016
.DISCUSSION...
Precipitation over the past several hours has generally been on
the decrease across the Texas Panhandle and northwest Oklahoma.
This trend will likely continue into the first part of Wednesday
as better lift with a shortwave trough moves across Kansas and
Nebraska.
The HRRR and Texas Tech WRF develop showers and storms this
afternoon along a surface boundary that roughly extends from
north of Lubbock into northwest Oklahoma. Overall confidence in
this scenario is not to high. However, another area of convection
near El Paso will continue to move north and east during the day.
Heating along with this "feature" may result in scattered to
widespread precipitation during the afternoon/evening. For now
western and northern Oklahoma will remain in a more favorable area
of showers and storms. A few of the storms in western
Oklahoma/western north Texas may produce locally strong wind gusts
mainly during the afternoon/evening.
A trough or the remains of Newton will keep rain chances fairly
high for western and northern Oklahoma on Thursday. This trough
will approach the southern Plains on Thursday and eventually will
move east of the area by Saturday. This will occur as a fairly
strong trough moves across the Rockies and northern Plains Friday.
An associated cold front will move into northern Oklahoma late
Friday afternoon and should clear southern Oklahoma and northern
Texas by early Saturday morning. Widespread showers and storms are
expected to form along the front with areas of heavy rainfall
possible.
Mainly dry conditions are expected for most of the weekend with
cooler temperatures and drier air.
Another front is expected to move across the area around Tuesday
and Wednesday of next week. Additional showers and storms are
possible with this frontal system.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 93 75 90 74 / 10 20 30 30
Hobart OK 93 74 93 73 / 30 30 30 30
Wichita Falls TX 95 75 95 74 / 10 10 10 20
Gage OK 90 70 93 70 / 40 30 40 30
Ponca City OK 92 74 89 74 / 30 50 50 50
Durant OK 93 75 94 74 / 10 0 10 10
&&
.OUN Watches/Warnings/Advisories...
OK...None.
TX...None.
&&
$$
03/06
Area Forecast Discussion
National Weather Service Pittsburgh PA
534 AM EDT Wed Sep 7 2016
.SYNOPSIS...
Warm and humid conditions will continue through Saturday, with
several disturbance providing shower and thunderstorm chances.
A cooler and drier airmass arrives on Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/...
530 AM update: made some updates to sky/PoP fields given current
trends. Areal coverage of showers is decreasing as convergence
area heads east, but should ramp up again later with instability.
Minor tweaks otherwise.
Previous discussion...
Area of low level convergence across the eastern CWA has worked
with moisture to fire off scattered showers. The HRRR has done a
good job with this activity so far, but wonder if increase in
coverage around 13-14Z is a bit overdone. Tops are below 20k feet
and no lightning is noted at present. Expecting some decrease in
coverage later this morning as convergence weakens and before
instability can build, but cannot go for a dry period this
morning.
PWATs will continue to increase today as the 500 mb ridge axis
sinks southward, allowing moisture plume to settle in. Still
expecting at least scattered convective development this afternoon
as temperatures aloft should cool sufficiently for more favorable
CAPE profiles. Morning activity could hinder destabilization
though, and uncertainty has led me to keep PoPs lowish for now,
although they may end up being too low. Severe weather threat is
minimal with weak shear and no significant dry layer aloft.
Coverage will diurnally decrease this evening as instability
wanes. Model soundings seem to justify hanging on to isolated
cells into late evening however. Expect a lull in activity around
12Z Thursday before the front to our northwest approaches.
Temperatures tricky today with the morning showers/clouds, but
still expect good heating to get values into the 80s to around 90.
Based the forecast today on mixed-down 850 mb temperatures and the
previous forecast. More of a general model blend was used for
temperatures tonight.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
The mid level ridge finally breaks down and moves east during this
period, allowing a frontal boundary to sink into the area by
Thursday afternoon. Although the surface low and better mid level
support ride off to the north, plenty of instability and good
frontal timing will result in scattered to numerous showers and
storms especially north of Pittsburgh. Wind shear looks slightly
better tomorrow, but still not sufficient for a notable severe
threat.
The front sinks southward across the area Thursday night, finally
settling somewhere near the Mason-Dixon line by 12Z Friday.
Activity along the front should slowly wane as the night wears on,
but chance PoPs will still be needed south of PIT towards sunrise.
Above normal temperatures will continue through this period, as
there is not a strong push of cool air behind the boundary.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Shortwaves embedded in southwest flow should continue shower and
thunderstorm chances until the passage of an upper trough and
associated cold front Saturday night. Ridging thereafter should
result in dry and cooler conditions Sunday through early next
week.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
Ceilings have held up to this point, with only a few locations
dropping to MVFR or IFR. DUJ is the only TAF site to do so
currently. As clouds increase later this morning, there could be a
brief period of MVFR ceilings before mixing pushes them back to
VFR. Tried to handle with TEMPO group for now.
Relative lull in precipitation early in the TAF period as earlier
showers decrease in coverage with slackening of low level
convergence. This afternoon, scattered convective development is
expected with building instability, and kept VCTS mention in TAFs.
Brief IFR is of course possible if any terminal gets hit. Any
convection will collapse after 00Z, with VFR continuing.
Fog possibilities will depend partially on where it ends up
raining. FKL/DUJ have the best chance of seeing restrictions
overnight.
.OUTLOOK /WEDNESDAY NIGHT THROUGH SUNDAY/...
Restrictions will be possible from time to time through Saturday
as several disturbances cross.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.
&&
$$
Area Forecast Discussion...CORRECTED
National Weather Service Charleston WV
252 AM EDT WED SEP 7 2016
.SYNOPSIS...
Weakness in the upper ridge allows convection across the northern
tier today. Weak front reaches the Ohio Valley Thursday night.
Stronger front with an airmass change arrives this weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 240 AM...
Will see an increase in the low level moisture
advection...particularly across the northern tier of counties in
the CWA this afternoon...with the mid and upper levels following
after 18Z. Hi res NAM depicting a weak disturbance riding around
the periphery of the ridge...providing the lift for convection
across north central WV in addition to the diurnal heating. Both
the RAP and HRRR concur with the NAM with the spatial placement of
the convection. Have taken the coverage of the POPs further west
from the previous forecast...into portions of eastern Ohio.
Convection expected to wane during the overnight period.
Given the temperatures yesterday higher than forecast...have kept
the trend of the increased values with prevalent lower 90s over
the Kanawha...Ohio...and Tug Fork valleys.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 245 AM Wednesday...
A cold front approaches from the northwest Thursday, slowly moving
east and spreading showers or storms Thursday night into Friday.
Bufkit soundings show thin CAPE feature with equilibrium level
exceeding 40 kfeet. So, expect tall thunderstorms ahead and along
the front. This front should then begin to pull back north as a
warm front late Friday...in response to an area of low pressure
approaching from the west.
Above normal temperatures with muggy conditions return through
Friday night. Went closer to the NAM and super blend numbers for
temperatures through the period.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 823 AM Tuesday...
Went with WPC thinking with some tweaks. A stronger cold front is
expected to push southeast Saturday into Saturday night with showers
and storms. There could also be a few showers in the mountains early
Sunday. High pressure will then build in during the day on Sunday
and continue in control of our weather through Monday night.
Temperatures should be close to normal values on Sunday and Monday...
before warming back up for Tuesday.
Chances for showers and storms will return on Tuesday as moisture
returns and a system approaches from the west.
&&
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
06Z Wednesday TO 06Z Thursday...
Isolated convection that has formed over the far northern
mountains of West Virginia has also been associated with a small
cumulus field in that area as well. Therefore...will limit the
potential for IFR fog at EKN from 10-12Z.
Elsewhere...given the trend of less fog coverage from continued
daytime drying...no other IFR or worse fog is in the forecast
tonight. This does come with some uncertainty...and will have to
watch for brief reductions in visibility around the 11-12Z time
frame at CKB and CRW.
More cumulus expected Wednesday...with isolated to scattered
convection from CKB east to EKN. Not enough for prevailing...and
beyond the scope of TEMPOs...but worth mentioning here in the
discussion.
Flows generally light...below 10kts. BKW and EKN may get an
isolated gust to 15kts.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY...
FORECAST CONFIDENCE: High.
ALTERNATE SCENARIOS: Late and brief fog development possible
around dawn. May need VCSH/VCTS at CKB or EKN this afternoon.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE WED 09/07/16
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13
CRW CONSISTENCY L L L L L L L L L L L L
HTS CONSISTENCY L L L L L L L L L L L L
BKW CONSISTENCY L L L L L L L L L L L L
EKN CONSISTENCY L L L L L L L L L L L L
PKB CONSISTENCY L L L L L L L L L L L L
CKB CONSISTENCY L L L L L L L L L L L L
AFTER 06Z THURSDAY...
No widespread IFR expected...but river valley fog could bring IFR
conditions during the early morning hours each day as low level
moisture increases.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...ARJ/26
NEAR TERM...JSH/26
SHORT TERM...ARJ
LONG TERM...JSH
AVIATION...26
Area Forecast Discussion
National Weather Service Amarillo TX
941 AM CDT WED SEP 7 2016
.UPDATE...
Made some adjustments to pops and max temps today based on latest
radar trends. Currently watching area of showers with a few
embedded thunderstorms moving northeast into our southwest zones.
This activity appears to be associated with an MCV with cyclonic
spin noted on the backside of the main precip shield. It will
continue moving north and should be in the amarillo between 16z
and 19z. The HRRR has handled this feature fairly well...but may
be advancing it a little too quickly through the area with storms
developing too far east this afternoon. Think our southeastern
zones will destabilize enough prior to MCV to get thunderstorm
development this afternoon. With the additional shower and
clouds...max temps were dropped a 3 to 5 degrees to nudge towards
short term guidance.
&&
.PREV DISCUSSION... /Issued 639 AM CDT WED SEP 7 2016/
AVIATION...
Showers moving northeast around 35 kt could wet runways at AMA this
morning. Southwest surface winds expected to gust into the 25 to 30
kt range most of the day. Mid- and high-level overcast layers
expected to prevail today and tonight. Scattered thunderstorms will
be most likely in areas south and east of terminals. Will include
thunder in forecast if a better signal for development emerges.
Cockrell
PREV DISCUSSION... /Issued 352 AM CDT WED SEP 7 2016/
DISCUSSION...
Moisture moving into our region with ties to Hurricane Newton will
impact our forecast going through the rest of the work week.
However, some of the local HiRes models are still not in total
agreement to timing and rainfall across the Panhandles. As of the
latest 07/00Z data, there is some agreement to the global models and
probabilistic data showing a upper level trough setting up over
southern New Mexico advecting moisture from Hurricane Newton into our
region with the 700 hPa theta-e axis set up across the central
Panhandles by Wednesday afternoon. This supports the latest GEFS/SREF
PWAT anomalies in the +2 to +3 S.D. across the Panhandles. Best
chances of precipitation at this time as seen in the latest 00Z data
will be across the central and eastern Panhandles downstream of the
main trough axis in the SW 850-700 hPa mean flow. As the upper level
high pressure compresses across the southeastern CONUS, the moisture
transport form the tropical system will also shift further to the
southeast as we go through the work week. This will confine the best
chances of showers and thunderstorms across the eastern Panhandles.
As we go from Friday night into Saturday, a trailing cold front from
a surface low over the Great Lakes will move south across the
Panhandles. Timing is not in agreement between the latest 00Z model
data for when the front will arrive, however the cold front will
work through the region by Saturday afternoon. The best chances of
widespread showers and thunderstorms will be across the eastern
Panhandles near the favorable upper level dynamics near the apex of
the main surface cold front moving south across eastern KS/OK. High
temperatures on Saturday behind the front will only range from the
mid 70s to lower 80s.
Once the cold front passes through the region on Saturday, tranquil
weather conditions will return to the Panhandles for the next
several days as high pressure builds back into the region. High
temperatures will also rebound into the mid and upper 80s.
As we go towards the end of the forecast period into the middle of
next week, another cold front will work south into our region.
Although a week away, the latest 00Z models are hinting that this
cold front may be a bit stronger as more favorable upper level
dynamics come into play. We will update the forecast accordingly as
time gets closer. Temperatures by middle next week maybe well below
average for mid September.
Meccariello
&&
.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.
&&
$$
7/9
Area Forecast Discussion
National Weather Service La Crosse WI
614 AM CDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
Issued at 345 AM CDT Wed Sep 7 2016
Main short-term fcst concerns are the continued heavy rain/flooding
threats today into this evening.
06z data analysis had the sfc trough/front near a KIMT-KLSE-KOMA
line. Boundary parallel to the mid level flow and making rather slow
progress SE. Very moist airmass (PW values near 2 inches) near the
boundary. WV imagery depicted a weak shortwave moving across southern
WI, with another stronger wave lifting NE across KS. Increasing
850- 700mb moisture transport ahead of the KS wave and into the
sfc-850mb trough producing a band of heavy rain producing
SHRA/TSRA from S WI to NE Neb. SHRA/TSRA tracking E-NE just north
of a KDLL-KDEH-KMCW line and posing a heavy rain/flooding threat
in those areas early this morning.
07.00z models look to have initialized well. Solutions now very
similar on a stronger wave to come around the base of the Rockies/
western plains trough and swings thru MN/IA/WI later this
afternoon/early this evening. Tight consensus for the main mid level
trough axis to then quickly progress into MN/IA by 12z Thu. Still
some smaller scale detail differences that impact the sensible
weather today into this evening but short-term fcst confidence is
average to good this cycle.
For the short term, stronger of lower level thermo-dynamic forcing
and moisture transport/theta-e convergence focusing on the the south
half of the fcst area today into this evening, near/south of the sfc-
850mb trough. This ahead of the shortwave lifting out of KS and
across the area around 00z this evening for even deeper forcing. As
much as 2" to 4" of rain has already fallen at some locations along
the MN/IA border across Vernon Co, with potential for another 1 to 3
inches, or more, thru today into this evening. Flood watch for at
least the south 1/2 to 2/3 of the fcst area today into this evening
seems well warranted. Continued with SHRA/TSRA chances in the 70-90%
range across the south 1/2 to 2/3 of the fcst area today. Some 50-
70% SHRA/TSRA chances across the north end, mainly this afternoon
with approach of the mid level shortwave. Passage of the mid level
shortwave and its portion of the trough axis quickly swings the 925-
700mb flow to the W-NW, pushing the deep moist airmass and the bulk
of the lower level forcing out of the fcst area thru the evening.
Carried highest SHRA/TSRA chances tonight in the 00-03z period,
trending down to 20-30% chances mainly across the east side of the
fcst area after midnight. Abundance of clouds expected today, to
limit the diurnal warming and looking to limit the CAPE as well.
Threats from TSRA other than the heavy rain and lightning looking to
be minimal today into this evening. Some decrease of clouds/clearing
later tonight and drying of the airmass should allow most lows to
cool into the low/mid 60s. Some concern for valley fog late tonight
into Thu morning, but the decrease of clouds later in the night
along with 10-20kts of W-NW wind just above the boundary layer
looking to limit the potential. Left any BR/FG mention centered on
12z Thu out of the fcst grids for now. Used a blend of the guidance
highs/lows for today/tonight.
.LONG TERM...(Thursday through Tuesday)
Issued at 345 AM CDT Wed Sep 7 2016
For Thursday thru Friday night: main fcst concerns this period
are returning SHRA/TSRA chances Fri/Fri night.
Model runs of 07.00z in good agreement for this period to start out
quiet as the trough axis exits quickly east and weak shortwave
ridging aloft builds across the Upper Midwest. The respite is short
lived as all models dig a rather vigorous shortwave trough into the
central/northern plains Thu night/Fri then swing it into the region
Fri night. This has been a rather consistent signal among the models
an fcst confidence for Thu-Fri night is good this cycle.
W-NW sfc-700mb flow behind the departing trough continue to spread
drier, and cooler air, across the fcst area Thu. After any lingering
early morning SHRA exit the NE end of the fcst area, a quiet, more
comfortable and partly cloudy to mostly sunny day expected Thu as
weak high pressure builds across the region. Strong shortwave
digging into the northern plains Thu night quickly returns SW flow
and lower level moisture transport and 925-700mb warm advection to
the area Thu night. Higher PW airmass from today is pushed east out
of WI/MN/northern IA, but that south of I-80 is pretty much left in
place. Thus the returning SW low level flow has plenty of reasonably
close higher PW air to draw northward ahead of the digging trough.
NAM looks a bit extreme pulling as much as 2+" of PW into parts of
the area by 00z Sat, while GFS looks low with only about 1.25" PW at
the same time. Even among the extremes both models and those in
between spreading another round of SHRA/TSRA across the area as the
sfc-mid level low/trough axis approach/pass Fri/Fri night. SHRA/TSRA
chances spreading in later Thu night then consensus 40-60% chances
for Fri/Fri night reasonable for now. NAM with its higher end PW
Fri/Fri night would produce another heavy rain threat across the
fcst area. Even the `drier` solutions would produce 1/2 to 1" of
rain across the fcst from 12z Fri to 12z Sat. Will have to get past
the heavy rain/flooding threat today before shifting focus to
Fri/Fri night. Used a blend of the guidance highs/lows for Thu thru
Fri night.
for Saturday thru Tuesday (days 4 to 7): main fcst concerns this
period are cooler temps for the weekend then small SHRA/TSRA chances
next week.
Medium range model runs of 07.00z in good agreement on the trough
moving east of the region Sat and rising hgts/shortwave ridging to
build across for later Sat into Sun night. Improving consensus for
more strong/longwave troughing to dig into the northern plains/
Rockies Mon then for a portion of this troughing to migrate into the
Upper Midwest Tue. With a tightening model consensus, at least thru
Mon, fcst confidence in the day 4-7 period is average this cycle.
Any lingering SHRA from the Fri/Fri night system into Sat morning
should be short-lived as brisk low level NW flow behind the
departing low/trough spreads a rather dry airmass into the region.
Dry Can high pressure settles thru the plains Sat, then moves east
across the mid MS valley Sunday, for what should be a seasonably
cool/dry/pleasant weekend for the region. 925mb temps both days
continue to indicate weekend highs mainly in the upper 60s to mid
70s, about a category below normal. Increasing SW lower level flow
progged to return for later Sun/Sun night. However, this time
around the deeper moisture has been pushed well out of/away from the
region and it will take some time to return. For now the earliest
this would be looks to be Mon. Timing differences crop up for Mon
night/Tue but trend is the sfc/low level trough/front with the
shortwave trough to move across the region. Until the details sort
themselves out, the small SHRA/TSRA chances Mon/Tue per the model
consensus okay for now. Temps Mon/Tue looking to remain near/a bit
below the normals and the model/ensemble consensus has these well
trended for now.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 614 AM CDT Wed Sep 7 2016
Local and regional radars showing the showers and storms over the
area currently moving east with a temporary back edge over
southwest Minnesota. The 07.10Z HRRR seems to have a good handle
on the current activity and brings this back edge across both
sites by the middle of the morning. This may only be a temporary
break in the activity as additional convection over Nebraska moves
northeast and comes back into the area by late morning. Another
round of convection will occur later this afternoon as the surface
low over western Iowa moves east/northeast ahead of the short wave
trough coming out of the Rockies. The models have been very
consistent in showing this next round staying south of both
airports. Visibilities and ceilings look to be primarily MVFR
with some IFR possible until the showers end this afternoon. With
all the low level moisture there is a concern for fog overnight.
The 07.06Z NAM forecast soundings show the low levels remaining
saturated through the night but the winds just above the surface
increase to 10 knots or greater behind the surface low. For now,
will show MVFR conditions overnight with some fog.
&&
.HYDROLOGY...(Today into this evening)
Issued at 345 AM CDT Wed Sep 7 2016
Very moist/warm airmass with PW values in the 1.5 to 2 inch range
and warm cloud depths near 4km remains over the area. With
progression of sfc thru mid level features, stronger of the lower
level thermo-dynamic forcing for SHRA/TSRA today into this evening
has shifted to mainly south of I-90. Any SHRA/TSRA in these areas
today remain capable of 1 to 2 inch/hr rain rates and 2 to 5 inches
of rain if TSRA end up training over the same location, capable of
producing flash flooding/flooding issues. With this southward focus
shift, will cancel flood watch for Clark/Taylor with the morning
fcst package. Watch thru this evening continues to look good for
areas along/south of I-90, but as day progress may be able to
cancel more of the watch north of I-90.
&&
.ARX Watches/Warnings/Advisories...
WI...Flood Watch through late tonight for WIZ032>034-041>044-053>055-
061.
MN...Flood Watch through late tonight for MNZ079-086>088-094>096.
IA...Flood Watch through late tonight for IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
HYDROLOGY....RRS
Area Forecast Discussion
National Weather Service Bismarck ND
900 AM CDT WED SEP 7 2016
.UPDATE...
Issued at 838 AM CDT Wed Sep 7 2016
Convection continues to push into western North Dakota with the main
line sliding over the Montana/NoDak border. Parameters are still
on tap for severe potential over southern locations, particularly
over south central ND into the southern James River Valley. Latest
high res guidance continues to show the stronger helicity pushing
through these areas mid-day into the mid-afternoon bringing the
potential tornadic threat. Minimal changes needed for mid-morning
update.
UPDATE Issued at 647 AM CDT Wed Sep 7 2016
The 06-10 UTC CAM suites have a good handle on the ongoing
convection this morning as expected in a strongly forced
environment and will follow their consensus solutions for the
remainder of the day. The severe thunderstorm threat in a high
shear/low CAPE environment remains unchanged across the south
central. The 10 UTC RAP continues its trend of depicting strong
low level shear around 25 kts, 0-1 km helicity in excess of 200
m2/s2 and very low LCLs across the south central and James River
Valley this afternoon. This draws particular attention to the
potential tornadic threat with any organized convection in these
areas.
&&
.SHORT TERM...(Today and tonight)
Issued at 301 AM CDT Wed Sep 7 2016
Focus in the short term will be on the potential for severe
weather south central into the James river valley this afternoon.
A well advertised upper level trough will move through the
Northern Plains today with a frontal boundary moving west to east
across the region. Showers and thunderstorms will move into
western North Dakota around 12 UTC and proceed west through the
day.
The latest short range model solutions bring a line of storms into
the Bismarck Mandan area around 17 UTC. This is potentially the
time when stronger storms may begin to develop in south central
North Dakota and north central South Dakota. Deep layer shear
values will be more than enough to support severe storms at this
time with values around 40 knots, however CAPE will be minimal.
Also with the early onset of storms the chances for severe storms
around Bismarck and points south along the Missouri river will be
limited.
East of Bismarck in the James river valley the later onset of
storms will allow for more surface heating, however CAPE values
will still remain on the lower side. Shear profiles on the other
hand will be more impressive with deep layer shear from 40 to 50
knots and low level shear enough to support a risk of tornadoes.
This lines up with the Storm Prediction Center slight risk area.
.LONG TERM...(Thursday through Tuesday)
Issued at 301 AM CDT Wed Sep 7 2016
Quiet weather expected to start Thursday before the next
disturbance pushes into the area bringing chances for
showers/storms. Weak ridging develops for the weekend bringing dry
conditions through Sunday afternoon. Next fast moving wave comes
through Sunday night into Monday bringing precipitation chances.
Models are hinting at the first cold airmass of the fall pushing
in Monday into Tuesday. Will have to keep an eye on this as if it
develops we can expect much cooler temperatures during that
period.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 647 AM CDT Wed Sep 7 2016
Numerous to widespread showers and thunderstorms are expected
to enter western North Dakota between 12-13 UTC this morning, and
spread east through the late morning and afternoon. MVFR/IFR
conditions in thunderstorms are expected. A few storms could be
strong to severe with large hail and damaging winds, especially
across south central North Dakota.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...MM
LONG TERM...MM
AVIATION...AYD
Area Forecast Discussion
National Weather Service State College PA
1009 AM EDT WED SEP 7 2016
.SYNOPSIS...
Hermine will linger off the coast today. The strong ridge aloft
over the MS/OH valleys will weaken a bit as storms break over the
ridge. Muggy air will stick around until a cold front passes
through this weekend. After a day or two of seasonable
temperatures Sunday and Monday another warm-up will occur.
&&
.NEAR TERM /THROUGH TONIGHT/...
Overnight shower activity in western areas has moved south of the
region. Strong subsidence on WV imagery over most of eastern PA
and more subsidence to west/southwest with the large upper-level
ridge over the Ohio Valley and Gulf States. Massive 5940 m ridge
is just to our southwest.
Larger scale models are a bit wetter than the CAMS today.
Successive HRRR runs show best chance of showers and thunderstorms
later this afternoon. SPC outlook for marginal risk is in close
proximity of the water vapor maximum axis over south-central PA.
Models are not too robust with the CAPE today.
The RAP and HRRR favor higher CAPE over western areas. Not
surprisingly the HRRR convective response is over central PA and
west. Tried to texture, and lower, larger scale POPs with HRRR.
Tried to show shower and thunderstorm potential better in western
areas. The HRRR facilitated showing some areas could get missed.
Need software to smooth that over 40km either side of a point to
make probabilities. The CAMS imply threat showers is late in
afternoon and evening.
Eastern areas will likely be rain free and quite warm today.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
Potential for lingering convection in morning in south-central PA.
This time is beyond the time range of our most available CAMS. But
these models to show lower POPS as ridge builds in stronger and
850 hPa temps go to 18-20C in the afternoon. Deep warm air mass
limits the model convective parameterization schemes (CPS) ability
to produce convection a bit.
Going to be a very warm late summer day. With the high PW air over
the region the RH is high. Thus our gridded forecasts show some
potential for apparent temperatures in the upper 90s to near 100
on Thursday afternoon. Something to be mindful of if working
outdoors Thursday afternoon and early evening.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Hermine will meander over the Gulf Stream for the next couple of
days with the latest 12Z guidance agreeing that it will likely
take until late Thursday or early Friday before it finally begins
moving up off the Cape Cod coastal waters.
Active northern branch of the jet stream is forecast to send
multiple shortwaves eastward across the northern tier of the
CONUS...bringing an increase in the chances for
showers/thunderstorms for late in the week.
A stronger mid level trof/surface cold front is advertised for
later Saturday with Sunday bringing the hiest chances of pcpn
during the period. Behind the front, it will turning slightly
cooler and noticeably drier into early next week.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR today for most part...once JST comes up after the rain. There
could be spotty areas of MVFR this afternoon and evening in
showers and thunderstorms. This will be an issue along with patch
fog overnight where it rains into Thursday morning. Some areas IFR
possible especially after midnight.
Any low clouds and fog should burn off to make for warm Thursday.
Mainly VFR Thursday with lower chance showers and storms. Models
imply some storms possible mainly in WNW sections.
Outlook...
Thu...Patchy AM fog possible. Isold PM tsra impacts possible,
mainly nw Mtns.
Fri...AM low cigs possible w mtns.
Sat...Isold PM tsra impacts possible, mainly w mtns.
Sun...AM log cigs possible w mtns.
&&
.CLIMATE...
Records today: IPT=95 and MDT=96.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Dangelo
NEAR TERM...Grumm
SHORT TERM...Grumm/Dangelo
LONG TERM...La Corte/Gartner
AVIATION...Grumm/Martin
CLIMATE...
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1104 AM EDT WED SEP 7 2016
.UPDATE...
The forecast looks to be in pretty good shape, and no significant
changes look to be made at this time. The top of the upper level
ridge over southeast Michigan is slowly getting pinched off and
weakening, and MLcapes building to between 1000-2000 J/kg this
afternoon with little in the way of a cap. A surface
trough/convergent boundary straddling the middle tier of the cwa
should be sufficient to generate scattered to low numerous
coverage (per 12z HRRR), mostly north of M-59. Temperatures close
to the same pace as yesterday (zero to -2 north of M-59/+2 to +4
south as of 15z), thus no big complaints with highs around
90/lower 90s, as 12z dtx sounding revealed an 850 mb temps of 19
C. 0-6 KM bulk shear looks to be mostly below 25 knots, but there
does look to be higher values across Tri- Cities, with downdraft
capes (1000+ J/kg) higher farther southeast. As such, will have
to keep an eye on the building instability, as a stray isolated
marginal severe wet micro-burst can`t be totally ruled out late
today.
&&
.PREV DISCUSSION...
Issued at 710 AM EDT Wed SEP 7 2016
AVIATION...
Early morning surface analysis and satellite imagery indicate an
outflow boundary in the FNT to MBS area and widespread coverage of
borderline IFR/MVFR stratus over northern lower Michigan. These
clouds are between the boundary and the main cold front still over
the northern Great Lakes. It does seem like some southward drift in
the stratus is likely during the morning as showers and storms
continue to reinforce the outflow from northern lower Michigan.
Daytime heating will eventually help lift the lower clouds but also
present potential for a new round of storms during mid to late
afternoon. These will be more scattered in coverage compared to
numerous/widespread coverage of showers and storms with the frontal
passage tonight. The front will also support a larger area of
IFR/MVFR ceiling and visibility restriction through Thursday
morning.
For DTW... Brief MVFR restriction in fog and/or patches of stratocu
will be possible through about mid morning. Some lingering haze will
be possible in the hot/humid air mass in place which will fuel
thunderstorm potential during the afternoon. Coverage of storms is
not expected to be very high in the D21 airspace but not low enough
to remove from the forecast.
//DTW Threshold Probabilities...
* Moderate for ceiling 5000 ft or less during afternoon.
* Low for thunderstorms late afternoon and evening.
PREV DISCUSSION...
Issued at 315 AM EDT Wed SEP 7 2016
DISCUSSION...
Very warm and humid airmass remains firmly in place this morning as
indicated by temperatures in the mid to upper 70s and dewpoints
solidly in the low 70s in most areas. Warm/moist southwest flow will
persist through Thursday as the longwave pattern flattens, but
remains largely unchanged over the Great Lakes. The deep trough over
the western US will not progress through the area, but will rather
decrease in amplitude and lift northeast around the subtropical
ridge, flattening it as it does so. As this happens, shortwaves
emanating out of the weakening trough will provide opportunities for
precipitation.
Showers are ongoing this morning along the low-level jet axis and
beneath a region of favorable jet support, mainly over Wisconsin and
Lake Michigan, but also weakly leaking into western Lower MI.
Showers have struggled to make it into Southeast Michigan, but may
find some success before sunrise as the LLJ axis gradually works
east before weakening during the morning. For this, just a chc pop
remains in place for the early morning hours.
High dewpoints, temperatures around 90 degrees, and advection of
steeper lapse rates aloft will likely result in moderate
destabilization by this afternoon. RAP ML CAPE is progged to reach
at least 1500 j/kg. At the same time, mid-level capping is notably
weaker than yesterday, and a developing surface low over the Upper
MS Valley will aid in a strengthening, but still modest (20+kts)
westerly LLJ nosing into the area during the afternoon. No qualms
with guidance such as the HRRR which indicates scattered t-storm
development getting under way in the 19-20z time window. Effective
shear will be quite weak, but a few strong wind gusts of 40 to 50
mph cannot be ruled out, especially with the mean flow behind any
cells that do develop. Heavy downpours a good bet with PWATs up
around 2 inches. High chc pops for this afternoon appropriate for
now, but concerns with regard to coverage and location preclude
going likely. Barring convective development occuring too early in
the day, heat indices are likely to reach 100 degrees in Detroit and
the surrounding urban corridor. A heat advisory has therefore been
issued for the far SE counties.
Dynamic forcing will increase markedly tonight, mainly from the
Saginaw Valley north, where a surface low will track between 00z and
12z Thursday. Categorical pops confined mainly to the waters of Lake
Huron and the immediate Saginaw Valley area. From I-69 south, it
will once again be a case of a rather ill-defined forcing field
mainly focused along the tail end of the LLJ/moisture transport
axis. Envision a scenario in which a slug of rain lifts across
Northern Lower while a corridor of trailing showers settles south
over the CWA, gradually dissipating with time. POPs therefore range
from categorical in the north to just 30 pops near the Ohio border.
Passage of tonight`s wave will sufficiently suppress the mid-level
thermal ridge to bring lower, but still warm, temperatures in the
mid 80s on Thursday. Surface moisture will remain in place, however,
ensuring another humid day and heat indices near 90 in the Detroit
Metro area.
Focus for the end of the week turns to the evolution of a strong
corridor of jet energy immediately south of the Aleutian Islands and
subsequent interaction with the remnants of Hurricane Newton,
presently located in the Gulf of California. NWP consensus exists on
a chunk of the remnant energy shearing northeast into SE Michigan
Friday night in advance of the rapidly deepening trough. Strong
isentropic ascent and moisture transport will likely result in a
corridor of moderate rainfall overnight Friday. Although NWP are
struggling with the exact nature of the interaction, a swath of rain
lifting through MI still appears probable. No changes to blended
grids at this time.
MARINE...
A weak frontal boundary will settle into Lake Huron today and
produce light and variable wind while maintaining modest southerly
wind over other marine areas. Wave response will be minor in this
pattern outside of thunderstorms which will be the most impactful
weather element in the forecast today through tonight. A ripple of
stronger low pressure is expected to move along the front tonight,
exit eastward into Thursday morning, and then pull the front through
the region. Light to moderate northwest to west wind will occur post
front through Thursday before weak high pressure arrives Thursday
night into Friday.
HYDROLOGY...
Warm and humid air will continue to stream into SE Michigan today
ahead of a cold front located over the northern Great Lakes and
Midwest. Scattered thunderstorms will be possible mainly during the
mid afternoon into evening, and with greater coverage in the Tri
Cities and northern Thumb region. This activity will be capable of
localized rainfall in the 0.5 to 1 inch range over small areas.
Another round of more numerous showers and thunderstorms will
develop during the day along the cold front to our west. This
activity is expected to move into SE Michigan during the night,
mainly after midnight through mid Thursday morning. Coverage will
again be greater in the Tri Cities and northern Thumb down to about
the I-69 corridor with a weakening trend expected to the south
toward the Ohio border. Rainfall potential will also remain in the
0.5 to 1 inch range but with greater coverage than during the day.
Isolated totals in excess of 1 inch will also be possible and could
lead to minor urban and small stream flooding.
Another larger low pressure system is projected to arrive in the
Great Lakes Friday night. This system is setting up to affect the
area with similar rainfall potential in showers and thunderstorms
Friday night through much of Saturday.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Heat Advisory until 8 PM EDT this evening FOR MIZ069-070-075-076-
082-083.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
UPDATE.......SF
AVIATION.....BT
DISCUSSION...JVC
MARINE.......BT
HYDROLOGY....BT
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Quad Cities IA IL
1035 AM CDT WED SEP 7 2016
.UPDATE...
Issued at 1033 AM CDT Wed Sep 7 2016
Incoming data so far this morning indicates thunderstorms will
re-develop this afternoon with the next approaching upper level
disturbance and then become widespread tonight.
Trends from the RAP are suggesting the heavy rain threat may
continue past midnight for much of the area. Based on this trend,
the flash flood watch has been extended until 7 AM Thursday.
&&
.SYNOPSIS...
Issued at 257 AM CDT Wed Sep 7 2016
Widespread thunderstorms with locally heavy rain continued
overnight across northern Iowa into southern Wisconsin. Scattered
storms were also beginning to develop in east central Iowa.
Unseasonably warm and humid air remained in place across the area.
Early morning temperatures were in the mid to upper 70s, with
dewpoints in the low 70s.
&&
.SHORT TERM...(Today and Tonight)
ISSUED AT 257 AM CDT Wed Sep 7 2016
The main forecast issues in the short term are the potential for
heavy rain and flash flooding, very high heat indices, and
possibly isolated strong to severe wind gusts. Hydro issues are
discussed below.
In the near term, storms should continue to increase in coverage
through the early morning, especially along and north of
Interstate 80. Per the various CAMS, there will likely be a
decrease in coverage from late morning into the early afternoon,
before the main system pushes through. Insolation will be limited
across the northwest half, with more breaks in the clouds
southeast. The model blend temp guidance looks reasonable, calling
for a high around 80 near Independence, and around 90 degrees
southeast. Afternoon heat indices should again peak mainly in the
95 to 100 degree range across the southeast two thirds of the
forecast area. We should be able to handle this again with a
special weather statement. Most of the forecast area remains in
the SPC day 1 marginal risk area. The main threat will be isolated
downburst winds with precip-loaded storms this afternoon and
evening, but this threat should remain localized.
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 257 AM CDT Wed Sep 7 2016
Thursday...Front exits to the east, taking rain chances with it.
Still warm with highs of 80-85 F for most areas. Humidity will lower
behind the boundary, except in the SE where dewpoints will be slow
to fall out of the lower 70s. Chances for showers and storms, albeit
on the low side (20-40%), back in the forecast overnight in elevated
WAA. Not anticipating widespread rain.
Friday...Remnant circulation and enhanced moisture from what was
tropical system Newton in the Gulf of California may bring another
risk for very heavy rainfall rates in a recharged tropical-like air
mass. Forecast environmental parameters on Friday are similar to
what is forecast for today (Wednesday):
1) Integrated Vapor Transport not as extreme, but still beyond the
90th percentile, over the SE forecast area, in the NAEFS 30-yr model
climatology for early September.
2) Rejuvenated PWATs, exceeding 1.75 inches, are near the NAEFS 97th
percentile. The tropical remnants are forecast to advect, ahead of a
fairly potent shortwave trough dropping in from the NW, through
northern Missouri, southeast Iowa, into north-central Illinois.
Similar to Wednesday, the tropical contribution to increased PWATs
and mid to upper level saturation is corroborated by 700-500mb
advection of ~90% RH into the region.
3) Warm cloud depths, especially over the SE third of the CWA,
aiding precipitation efficiency.
Thunderstorm Risks: Localized flash flooding from thunderstorms
producing heavy rainfall rates of 1-2"/hr are the primary risks.
There is also a marginal risk for severe storms along/south of I-80.
Confidence and Timing: High on occurrence of heavy rain producing
storms Friday afternoon into the night. At this time, areas south of
I-80 are in the more likely zone to receive the heaviest rainfall
rates and totals. Being a few days away, plenty of time for
adjustments to the forecast.
Saturday and Sunday...Dry and cooler behind compact shortwave
trough. Highs in the 70s and lows in the 50s.
Monday and Tuesday...A bit warmer and more humid on Monday. Then
another cold front brings chances for showers and storms, mainly
Monday night and Tuesday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
ISSUED AT 636 AM CDT Wed Sep 7 2016
Periods of storms to impact KDBQ, KCID, and KMLI this morning with
redevelopment this afternoon and evening. Expect periods of IFR
to MVFR visibilities in storms. Thunderstorms may linger through
the overnight hours at KBRL.
&&
.HYDROLOGY...
Issued at 257 AM CDT Wed Sep 7 2016
Have expanded the flash flood watch south to Interstate 80, and
extended it through 06z tonight. Widespread 1 to 2 inches of rain
are expected through tonight, with isolated higher amounts of 3 to
5 inches. This is supported by moisture contributions from
Hurricane Newton, which will likely help boost precipitable water
values to record September levels for the area, possibly around
2.4 inches.
The main flash flood threat is expected to be this afternoon
through this evening. Locally heavy rain is also possible south
of the watch area, and the watch may need to be expanded even
more later today.
There is potential for more heavy rain later this week,
especially Friday and Friday night as remnants of Newton continue
to stream into the region. Renewed rises are likely on many area
rivers, with some points potentially going back above flood stage.
Flash flooding will also be a factor as the ground continues to
saturate.
&&
.DVN Watches/Warnings/Advisories...
IA...Flash Flood Watch through Thursday morning for Benton-Buchanan-
Cedar-Clinton-Delaware-Dubuque-Iowa-Jackson-Johnson-Jones-
Linn-Muscatine-Scott.
IL...Flash Flood Watch through Thursday morning for Carroll-Jo
Daviess-Rock Island-Stephenson-Whiteside.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...RP Kinney
SHORT TERM...RP Kinney
LONG TERM...Uttech
AVIATION...RP Kinney
HYDROLOGY...RP Kinney
Area Forecast Discussion
National Weather Service Grand Forks ND
Issued by National Weather Service Bismarck ND
1004 AM CDT WED SEP 7 2016
.UPDATE...
Issued at 1004 AM CDT Wed Sep 7 2016
Overall forecast trends on track. Solid line of showers and
thunderstorms western ND continue to advance northeast. Latest
HRRR continues with the trend of developing the leading edge of
precipitation into the Devils Lake region around 18z, then
increasing southward through 21z. HRRR hourly updraft helicity
values increase very close to 100 between 22z and 23z far southern
James River Valley, then into our southeast zones through 03z
Thursday. This is in line with SPC Day 1 Tornado threat.
UPDATE Issued at 651 AM CDT Wed Sep 7 2016
Made some tweaks to POPs to keep thunderstorms to this afternoon.
Still think we could see storms, possibly severe, entering the
southwestern counties around 20Z this afternoon. Also added some
patchy fog for some spots in the northern counties such as KBDE
and KRDR that have seen visibilities drop.
&&
.SHORT TERM...(Today and tonight)
Issued at 340 AM CDT Wed Sep 7 2016
Convection timing and strength this afternoon and tonight will be
the main forecast problem for the period.
High pressure remains over much of the forecast area and dew
points are still in the upper 40s and 50s as of 2 AM CDT. However,
better moisture with 60s dew points is just to our southern
border, and surface winds will shift around to the southeast
throughout the morning. The upper trough currently over MT is
progressing rapidly to the east, and should move into the Western
Plains by late afternoon. This will help push the surface trough
axis currently over eastern MT/WY eastward and into the western
CWA by late afternoon. While temps may be limited a bit by
increasing clouds, still think we should get into the upper 60s to
low 70s across the southwestern counties. This should help
instability get up to around 1500 J/kg by this afternoon. While
this is not insanely high, there will be 50 kts of deep layer bulk
shear and upper support will be good for storm development. The
NSSL WRF and HRRR both bring some fairly significant storms into
our southern counties by 20Z or so. The WRF runs show mostly
convection in a linear bow, but with the low level wind profile
bringing some nicely curved hodographs there will be a threat of
tornadoes possible at least in our southern counties.
The system will be quickly moving, with the surface low moving
into MN by early evening and off to the east of our counties after
midnight. The NAM puts out some high QPF values in a similar track
over areas that received heavy rain Sunday night. However the
other global models are further south with the heaviest rain. In
addition, with the quick movement of the system think that unless
we get cells training over each other that flooding will not be
too much of a problem. Rain should end from west to east during
the night with only a few lingering showers near Lake of the Woods
by early Thursday morning. Lows will be mostly in the 50s.
.LONG TERM...(Thursday through Tuesday)
Issued at 340 AM CDT Wed Sep 7 2016
Thursday through Friday...Southwesterly flow aloft continues with
several decent shortwave troughs moving through. Think that most
of the day on Thursday should be fairly quiet, but one of the
shortwaves will help push a surface trough into the Red River
Valley Thursday night. Moisture recovery will not be as good and
much of the upper support will be to our south or north so kept
POPs a bit lower in the 20-40 percent range. The surface low will
move east during the day on Friday but the main upper trough will
still be pushing through and models are indicating some signs of
mid level frontogenesis behind the surface boundary. Will keep
chance POPs going for Friday and then taper them off Friday night
as the upper trough digs into the Upper Mississippi Valley. Temps
should be near seasonal averages on Thursday in the upper 60s to
mid 70s but a bit cooler for Friday.
For Saturday...upper level trof shifts over the area in the wake of
a cold front. Thus...expect cooler temperatures across the region to
start the weekend. Precipitation ends as surface high pressure
builds in...allowing for more pleasant conditions along with light
winds.
By Sunday night into Tuesday...the pattern continues to be
progressive as an upper level ridge shifts across the northern
plains. Surface high pressure retreats to the east allowing return
of southerly flow. Therefore...will see warmer temperatures
spreading across the region ahead of another system...and increased
chances of showers or storms for the Monday time frame.
Otherwise...cooler and more tranquil weather is expected to end the
period.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 651 AM CDT Wed Sep 7 2016
All sites are currently VFR although KGFK has been bouncing up and
down in visibility and nearby KRDR is reporting fog. Will include
a tempo group for some MVFR vis for an hour or so, but fog should
dissipate with sunrise and cirrus starting to move in from the
south and west. The cirrus will increase throughout the day, and
this afternoon expecting storms to enter the area. Have VCTS
mention moving west to east, starting at KDVL at 19Z and ending at
KBJI at 04Z. Models are indicating a line of convection moving
through, but uncertain on northern extent so just have prevailing
TSRA only at KFAR for now and will keep the other sites at just
VCTS. Some MVFR to IFR cigs will be possible at KBJI and KTVF
along and just behind the storms, with the more western sites VFR.
Have all sites but KBJI up to VFR by the end of the period. East
to southeast winds today will shift around and become westerly
behind the storms tonight.
&&
.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&
$$
UPDATE...KS
SHORT TERM...JR
LONG TERM...JR/Hopkins
AVIATION...JR
Area Forecast Discussion
National Weather Service Hastings NE
636 AM CDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
Issued at 407 AM CDT Wed Sep 7 2016
Aloft: SW flow remained over the Cntrl Plains...with a
subtropical high over the lwr MS Valley and a broad deamplifying
trof over the Wrn USA. Multiple embedded shortwave trofs will
knock down the ridge over the Ern USA...carving out a broad trof
over the Nrn 1/2 of the CONUS by daybreak Thu. The remnants of
Newton will lift into AZ today. The leading edge of its mid-lvl
circulation will get sheared to the NE and make it into SW KS by
Thu morning.
Surface: An elongated front extended from UT/CO across the Cntrl
Plains to the Great Lakes. This front was just S and E of the fcst
area...extending from W-cntrl KS into SE Neb. This front will
remain quasi-stationary today...but as heights fall downstream the
front will get nudged a little further S and E of the fcst area
tonight...with a small high building over Neb.
Overnight...once again the beneficial rain fell in areas that did
not need it (N-cntrl KS) and did not fall in areas that
desperately need it (nearly all of S-cntrl Neb). A mesonet site
near Palco (Rooks County KS) measured 3.13 in 6 hrs. Please see
hydro section below.
Now thru sunrise: the dissipating remnants of earlier tstm
activity will cont to move NE and exit the fcst area. While the
main low-lvl jet axis is veering toward IA/MO...rgnl 88D wind data
suggest 20-35 kts is still aimed toward the fcst area with speed
convergence implied. The 07Z HRRR suggests more shwrs could
develop. With the atms overturned by earlier convection...it`s
doubtful enough instability exists for thunder...although an
isolated strike or two can`t be completely ruled out.
We also will be monitoring for patchy fog. Dwpt depressions are
small (2-3F) and winds are light. Any radiating will result in
fog. Just not sure how bad or widespread it could be.
Cloud cover: There is an expansive shield of multi-layered mid-
high clouds streaming into the region ahead of Newton (now ovr the
Gulf of CA). While some of this could thin at times...overall
believe skies will be m/cloudy thru tonight. The NAM shows these
high clouds are on the higher tropopause and heights will not
begin to fall (shoving the cloudband SE) until late tonight...as a
shortwave trof heads into the Dakota`s.
Today: Possibly a few shwrs this morning. Otherwise m/cloudy...
with temporary improvement to p/cloudy at times. Can`t completely
rule out an isolated tstm this afternoon E of Hwy 281. But most
locations will be dry today.
Tonight: Possibly an isolated tstms on the extreme E fringe of
the fcst area. Otherwise dry under m/cloudy skies.
Not expecting any strong/severe storms and this agrees with SPC
risk of just general tstms.
.LONG TERM...(Thursday through Tuesday)
Issued at 439 AM CDT Wed Sep 7 2016
Thursday and Thursday night are a bit murky and confidence is low
here. With a stalled out boundary nearby or to the south and
increasing warm air advection, we could have some nocturnal
convection erupt. However, there is a lot of discrepancy in the
model world, and I wouldn`t hang my hat on getting precip.
However, if storms develop, mid-level lapse rates should be steep
enough for some strong to severe thunderstorms. It`s a tough call
on where the front will be, and if it lies in our southeastern CWA
like I expect it might, we could be in for some fog near the
boundary.
For Friday, we could get some firing of thunderstorms east/
southeast along the cold front, and we finally get a solid push
from a mid- level trough that will clear the front from our area
for awhile.
On Saturday, we will be to the west of a departing wave, so I
expect dry weather through Sunday night with general subsidence.
The next trough heads south into the western United States on
Monday, helping to push a a strong cold front through, which will
lower temperatures and dewpoints noticeably. Multiple impulses of
energy may be repeatedly sent into the central Plains thereafter
in the post-frontal regime, giving us the potential for a number
of relatively cloudy, cool, and damp days next week with highs
only in the 60s for Tuesday and a few days thereafter.
&&
.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Thursday)
Issued at 636 AM CDT Wed Sep 7 2016
Significant Wx: Possibly MVFR fog until 14Z this morning.
Today: Probably VFR to start. Conditions are ripe for fog...but
high OVC is inhibiting radiational cooling. Even with the high
clouds...some SCT stratus around 300-500 ft is possible along with
temporary MVFR fog. Multi-layered mid-high clouds after 15Z will
be joined by SCT CU around 4000 ft beginning around 17Z. Lgt and
vrbl winds. Confidence: Medium
Tonight: VFR with BKN cirrostratus around 25K ft. There is an
outside chance for MVFR fog...based on pattern recognition...but
fcst guidance is not indicating it. Lgt NW winds under 10 kts
eventually become NNE after 05Z. Confidence: Medium
&&
.HYDROLOGY...
Issued at 407 AM CDT Wed Sep 7 2016
Another area of R+ occurred upstream of Phillips/Rooks/Osborne
counties. Ground truth is limited...but MRMS 12 hr radar estimates
are very close to the 2.66" that fell at HLC and the 3.13" that
fell near Palco. So confidence is high that the swath of MRMS
estimates of 4-7" is legit. Some of this will be running off into
Wildhorse and Lost Creeks...and ultimately into the S Fork of the
Solomon Rvr. We are already seeing the initial response in Damar
and Woodston.
In anticipation of renewed rises on area creeks and rvrs...we
issued a Flood Watch last eve at 1134 pm and it conts as posted
thru 6 pm today. This Watch may need to be extended. In coord
with the Rvr Fcst Ctr...we are expecting creeks and rvrs that fell
below flood stage to rise and flood again. Please follow Flood
Statements and possibly additional Warnings from this office.
It appears we do have a break coming with no heavy rainfall
expected for svrl days. This should allow creeks/rvrs to process
the run-off and then drop below flood stage and remain within
their banks for a while.
&&
.GID Watches/Warnings/Advisories...
NE...None.
KS...Flood Watch until 6 PM CDT this evening for KSZ005-017-018.
&&
$$
SHORT TERM...Kelley
LONG TERM...Heinlein
AVIATION...Kelley
HYDROLOGY...Kelley
Area Forecast Discussion
National Weather Service Goodland KS
529 AM MDT WED SEP 7 2016
.SHORT TERM...(Today through Friday night)
Issued at 332 AM MDT Wed Sep 7 2016
Early morning WV imagery and RAP upper level analysis shows SW flow
in place across the plains ahead of large scale upper trough over
the western US. Severe shortwave troughs are progressing through the
mean flow with one over eastern Nebraska and another in southeast
Colorado. At the surface a stalled front extends across our southern
CWA with a low pressure centered over southeast Colorado.
This morning: Stratus/fog have developed across the northwestern
part of our CWA, and vis has briefly dropped to 1/4 to 1/2 miles at
a few locations. Confidence is low that this would prevail or be
widespread and visibilities have fluctuating a lot in these areas.
Will continue to monitor for more persistence in dense fog coverage,
but for now I am not anticipating a dense fog advisory (continuing
to handle with Special Weather Statement).
Today-Thursday: Air mass aloft changes very little, and with good
available moisture and moderate instability there is a potential for
thunderstorms through these periods. Confidence is lower as better
large scale forcing will be shifted to our southeast, and models
show little in the way of initiation. With stalled front nearby I
can`t rule out thunderstorms late this afternoon and overnight,
however better chances still appear to be Thursday afternoon/evening
as the remnants of Hurricane Newton move through the southern
plains. Even then there is not a lot of confidence and we may
actually see larger Td depression spreads through a deep layer of
the atmosphere (as shown by GFS) which would possibly limit coverage
(if something were to initiate. I didn`t make major changes to
ongoing PoPs forecast, favoring model blend/consensus. Temperatures
are generally going to be near seasonal levels, though this could be
dependent on cloud cover and clearing. With better clearing daytime
temps could be closer to 90F and overnight lows below 60F.
Friday-Friday night: A shortwave trough moves across the Northern
Plains and kicks a cold front south over our CWA. With deeper dry
layer in place and better forcing north of our CWA, the main impact
on sensible weather should be on temperatures. Below normal highs
and lows are expected with many locations in the 70s on Friday.
Chilly temperatures in the 40s will be favored for most locations,
and I could see a few low spots in the west possibly drop to the
upper 30s (based on dryness of BL).
.LONG TERM...(Thursday through Tuesday)
Issued at 223 AM MDT Wed Sep 7 2016
The general pattern for the extended period starts with dry weather
and gradual warming conditions over the weekend followed by chance
of storms returning to the area beginning of the week and
lasting through the rest of the period.
High pressure will build over the region behind a strong cold front,
that will pass through the area on Friday. The air behind this front
looks to be cool and dry. This will produce mostly clear skies and
light winds for the weekend. The high temperatures will reach the
upper 70s on Saturday and upper 80s on Sunday. Overnight temps will
drop into the mid 50s.
At the start of the week the models are showing another front
passing through the Tri-State area and producing chance of storms
from Monday through the end of the period (Wednesday). At this time
confidence is to low. So I will wait until tomorrow night`s run to
expand on the details.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 529 AM MDT Wed Sep 7 2016
Low confidence early in the TAF period due to pockets of low
stratus/fog and rapidly changing cigs/vis in obs surrounding KGLD
and KMCK. Pattern north of front (stalled just south of KGLD)
supports increasing fog/stratus coverage before improving to VFR
around 15Z. Higher resolution guidance is picking up on patchy
nature of the fog, but does little to narrow down timing of
category changes. IFR appears likely early in the TAF period, and
there is the possibility for dense fog and LIFR conditions. I am
not confident enough to even carry a tempo group for those lower
conditions during this update. Winds are expected to remain below
10 KT through the TAF period with weaker surface gradient in
place.
&&
.GLD Watches/Warnings/Advisories...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BW
AVIATION...DR
Area Forecast Discussion
National Weather Service Houston/Galveston TX
934 AM CDT Wed Sep 7 2016
.DISCUSSION...
A couple of moisture plumes were over the eastern and western
counties of the forecast area. The HRRR does show the potential
for isolated showers and thunderstorms in between these areas
later this afternoon when the sea and bay breeze move inland and
become active.
The current forecast is on track and no changes are planned at
this time.
40
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 93 75 93 74 92 / 20 10 20 10 20
Houston (IAH) 93 76 92 75 91 / 20 10 30 10 30
Galveston (GLS) 89 82 88 82 89 / 20 10 20 20 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Discussion...40
Aviation/Marine...47
Area Forecast Discussion
National Weather Service Lincoln IL
955 AM CDT WED SEP 7 2016
.UPDATE...
Issued at 947 AM CDT Wed Sep 7 2016
The widespread convection just to our north has made it about as
close as the Quad Cities, but continues to track northeast and
mainly clear skies prevail over the CWA this morning. Shortwave
currently over the Kansas/Nebraska area will help trigger
additional development to our west this afternoon, and latest runs
of the HRRR continue to feature scattered showers and storms over
the areas northwest of the Illinois River by late afternoon. Have
increased PoP`s a bit in this area through this evening, when more
of the focus of showers and storms will be there. Have maintained
the isolated showers/storms over the southeast CWA, with the HRRR
continuing to show this potential, and with little change from
previous days when the showers did occur.
No change made to temperatures, with heat index values still
expected to get close to 105 degrees over the southeast CWA and a
couple degrees either side of 100 elsewhere.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 321 AM CDT Wed Sep 7 2016
07z/2am surface analysis shows high pressure over Tennessee, while
slow-moving cold front remains draped further northwest from the
Upper Peninsula of Michigan southwestward to Nebraska. Widespread
convection has developed along this boundary, with a few isolated
showers further south across portions of central/eastern Iowa. HRRR
has consistently shown these showers developing/spreading further
east into north-central Illinois this morning. As a result, have
carried slight chance PoPs north of the Peoria area. Further south
across the remainder of the KILX CWA, another very warm and humid
day is on tap. Southwesterly winds gusting to between 20 and 25 mph
at times will continue to transport high dewpoint air into the
region. Afternoon high temperatures will once again reach the lower
90s, while heat index readings range from 100 to 105 degrees. While
synoptic forcing will be absent, a few of the high-res models such
as the WRF-ARW and HRRR suggest isolated convection may develop
across the E/SE during peak heating. Since this has happened the
past two days, decided to mention isolated thunder east of I-57
this afternoon.
As a short-wave trough currently evident on water vapor imagery over
the Northern Rockies tracks eastward and begins to flatten the
prevailing upper ridge over the Midwest, it will push the cold front
toward Illinois tonight. Numerous showers and thunderstorms will
develop along/ahead of the front within the very moist airmass
characterized by precipitable water values in excess of 2 inches.
While 0-6km bulk shear will initially be quite weak, it will
increase to 30-35kt along/north of a Rushville to Bloomington line
this evening. This suggests the potential for some organized
thunderstorms capable of gusty winds and locally heavy rainfall.
Have carried likely PoPs across this area this evening accordingly.
As the front sinks slowly southward, rain chances will spread
across all but the far SE CWA after midnight.
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 321 AM CDT Wed Sep 7 2016
As was first seen with the 00z Sep 6 models, the latest model suite
shows the cold front settling southward into central Illinois on
Thursday as a weak area of high pressure builds into Iowa/northern
Illinois. As a result of this southward push, have ended rain
chances across the northern CWA Thursday afternoon. The boundary is
still expected to stall late in the day, with a weak wave of low
pressure developing and tracking along it Thursday night into
Friday. Models are still not in perfect agreement here: however,
general consensus focuses best rain chances across the southern half
of the area. Have therefore gone with likely PoPs along and south
of I-72 on Friday, with chance PoPs further north.
A stronger short-wave trough is progged to track across the Plains
Friday night, giving the persistent frontal boundary a solid push
eastward. Given increasing synoptic lift associated with the
approaching wave and ample deep-layer moisture, likely PoPs are
warranted across the board Friday night. The front still appears to
sweep through the region fairly quickly on Saturday, with the GFS
being the slowest model. Have maintained chance PoPs across the
east through Saturday morning, then gone dry everywhere by
afternoon. Main weather story this weekend will be the cooler and
drier conditions, as high temperatures drop into the 70s for both
Saturday and Sunday. After that, the next significant chance for
rain will hold off until next Tuesday at the earliest.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 659 AM CDT Wed Sep 7 2016
Although isolated thunderstorms will be possible through afternoon
today...likelihood is too low for mention until 00Z-04Z as a cold
front approaches from the northwest with scattered to numerous
thunderstorms developing ahead of the front. Expect VFR conditions
with scattered cloud cover around 5000-6000 feet until then...with
showers and scattered thunderstorms afterward. Periods of
thunderstorms may contain MVFR cigs/vsbys but timing of these
periods uncertain at this time. Winds SSW up to 10 kts becoming
SSW 10-15 kts with gusts 20-25 kts after 16Z- 17Z. Wind gusts
decreasing after 00Z although stronger thunderstorms could contain
strong gusty winds over 40 kts.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...Geelhart
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Onton
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1040 AM CDT WED SEP 7 2016
.UPDATE...
Made small changes to the overall hourly trends to bump up hourly
temps and adjust dewpoints lower in the east. Took out thunder in the
west earlier and only left showers this afternoon. /DC/
&&
.DISCUSSION...
Overall a very quiet afternoon continues to be in store as 597 upper
ridging and drier air wedging from the east will keep the area mostly
dry for the afternoon. Morning PW`s have fallen near half an inch
below 1.5 inches or so, with higher moisture in the west. We should
efficiently mix into the low to mid 90s in the east. Water vapor
imagery shows the dry air aloft being expansive over the area and we
may be able to mix out dewpoints to the lower 60s in the east. Higher
PW`s closer to 2 inches will help dewpoints hold up in the lower 70s.
Thus, could have some heat indices peaking above 100 degrees in the
ArkLaMiss Delta but only sporadic areas in the far northwest could be
slightly warmer. Overall dry air will preclude any heat issues. Some
showers are possible in the west but may struggle to have much any
thunder overall due to limited lapse rates and high moisture. Rest
of the forecast is out. /DC/
&&
.AVIATION...VFR flight categories are expected at all TAF sites this
afternoon and through much of tonight. Some patchy fog is possible
around day break Thursday, especially at KHBG. Categories where fog
is observed could be reduced to MVFR/IFR status due to degraded
visibilities and ceilings. Any patchy fog that develops, will likely
dissipate by 14Z Thursday. Winds today will be from the south
southeast between 3-8 knots. /19/
&&
.PREV DISCUSSION... /issued 400 AM CDT WED SEP 7 2016/
SHORT TERM...Today through Thursday night...Water vapor imagery
this morning showing much drier air working its way into the forecast
area from the east. Total precipitable water imagery in agreement
with the RAP with PWs less than 1.5 inches already into the eastern
half of the area. The dry airmass will continue to slowly progress
westward in the short term, but PWs greater than 1.5 inches look to
hold on in the west today and the far west on Thursday. This should
result in isolated shower and thunderstorm development in the heat of
each afternoon.
The dry airmass will promote more efficient heating and deeper
mixing in the east today and Thursday. This will make the mid 90s
attainable over a large area. Conversely tonight and Thursday night,
the dry air will support better radiative heat loss and the
potential for minimums as low as the mid 60s./26/
LONG TERM...Friday through Wednesday...The effects of the upper-
level ridge will still be felt across the ArkLaMiss on Friday, with
subsidence keeping drier air across the area and rain chances low.
Afternoon relative humidity values could drop to between 35 to 45
percent for most locations. Then model guidance shows good agreement
for the ridge to break down over the weekend and into early next
week as a shortwave trough slides across the northern CONUS.
Meanwhile a developing surface low near the Great Lakes will drag a
cold front into the southeastern U.S. as it pulls eastward. Have
trended a little more aggressive with the cold front for this
forecast, based on guidance which suggests the front could make it
into the forecast area late Saturday. Some question remains about how
far southward the front will make it, but think it should push far
enough to bring high temps to near normal on Sunday and min temps
down to the mid 60s for northern zones for Monday morning. Areas
closer to the coast will probably remain on the warmer and more humid
side as the front washes out across the Gulf Coast. Primarily, the
front should serve as a focus for potential convection as it moves
southward, so best POPs currently focused along and south of the
front where deeper moisture will be in place each day. Model guidance
tries to develop some semblance of a ridge of high pressure across
the southern CONUS again by the middle of next week, with moist
southerly flow returning to the lower levels across the region. Have
therefore kept slight chance POPs for afternoon showers and
thunderstorms through the extended period./NF/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 93 70 94 68 / 9 11 11 4
Meridian 95 67 95 67 / 2 7 7 0
Vicksburg 93 71 93 68 / 19 10 12 7
Hattiesburg 92 68 92 67 / 3 4 5 4
Natchez 91 71 91 68 / 24 3 8 5
Greenville 94 73 92 71 / 17 8 17 5
Greenwood 93 70 93 69 / 6 8 12 3
&&
.JAN Watches/Warnings/Advisories...
MS...None.
LA...None.
AR...None.
&&
$$
DC/19
Area Forecast Discussion
National Weather Service Louisville KY
1126 AM EDT WED SEP 7 2016
...Forecast Update...
Issued at 1125 AM EDT Wed Sep 7 2016
This morning`s HRRR is keying in on our southern Indiana counties
for development this afternoon, but yesterday`s runs did a poor job
with the I-65 corridor...where nothing developed in the afternoon.
That model is not handling the capping aloft in place very well.
Today`s AMDAR soundings shows the cap is a little higher up, which
may allow for a deeper cumulus field to develop. Best precipitable
water is over our northern counties, but even that is only in the
1.5-1.7 inch range. Cannot rule out a very isolated shower, but as
was the case yesterday will keep the forecast at a silent less than
15% pop for now and amend if necessary as we see the cu-field
develop.
High temperatures in the lower 90s at all our mains sites still looks
good. Current forecast handles this well, and only change in this
update is to remove the morning fog wording.
.SHORT TERM (Now through Thursday)...
Issued at 245 AM EDT Wed Sep 7 2016
The upper ridge will hang on for one more day resulting in a mostly
dry Wed. The exception to that may be a very isld shower in the
area. This chance is too low to go with anything higher than a 10%
POP. Hot temps will continue with highs in the low 90s today and
lows in the upper 60s/lower 70s tonight.
Thursday a weak front will enter the region bringing chances for
showers/storms back into the Ohio Valley. The best area for
scattered storms Thu will be southern IN and north central KY. While
severe weather is not expected, a few strong storms could produce
gusty winds and brief heavy rainfall. Temps on Thu should range
from the upper 80s over southern IN to upper 80s/low 90s over
central KY.
.LONG TERM (Thursday night through Tuesday)...
Issued at 245 AM EDT Wed Sep 7 2016
Thursday Night - Saturday...
Scattered showers/storms will continue Thu Night - Fri as a weak
boundary with multiple shortwaves riding along it spark convection.
Exact timing in this setup is hard to pin down but southern IN will
continue to see the best chances for convection being closer to the
boundary.
Fri night the weak boundary will lift north as a warm front before a
strong cold front and upper trough push through the Midwest on Sat.
So we will see a good dry period Fri night before showers/storms
associated with the cold front approach the region Sat morning.
Expect a breezy day Sat on approach of the front with a round of
storms potentially strong in nature.
For temperatures, have decreased highs for Fri as the latest model
guidance indicates the boundary will be close enough to southern IN
to keep them rather cloudy with sct showers/storms limiting highs to
the mid 80s. Expect a gradient of temps from the mid 80s to low 90s
over central KY Fri afternoon depending on exact placement of
convection/clouds. Lows both Thu/Fri nights will remain mild in the
low 70s. Sat high temps will be determined on
clouds/convection/fropa ranging from the low 80s over SW Indiana to
upper 80s near Lake Cumberland in KY.
Sunday - Tuesday...
Sun/Mon will feature dry weather with pleasant temps. Sun will be
the cooler of the two days with highs in the mid 70s to around 80
and lows in the 50s! Mon will be a little warmer with highs in the
low 80s.
Another weakening front will try to make its way into the region
toward mid week but so far it does not look too impressive in
producing much precip.
&&
.AVIATION (12Z TAF Update)...
Issued at 635 AM EDT Wed Sep 7 2016
High pressure and ridging aloft will remain in place with quiet
weather continuing. The only concern will be the transient fog at
BWG this morning and possibly again tomorrow morning. Visibilities
this morning will bounce around for the next couple of hours before
becoming VFR for the remainder of the day. Winds will pick up out of
the southwest through the morning. Scattered cu will develop once
again.
&&
.LMK Watches/Warnings/Advisories...
KY...NONE.
IN...NONE.
&&
$$
Update.........RJS
Short Term.....AMS
Long Term......AMS
Aviation.......EER
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1028 AM CDT WED SEP 7 2016
.UPDATE...
Issued at 1028 AM CDT Wed Sep 7 2016
With the additional heavy rain threat in the short term models and
incoming 12z models continuing to shift south for the rest of
today and tonight, we did cancel what remained of the flood watch
this morning.
Our attention now turns to the potential for thunderstorms this
afternoon/evening. The hrrr is certainly aggressive with driving a
squall line across much of the area tonight and think it may be a
little too far south with the southern extent of the line, with
the best llj and shortwave forcing going up across NW MN. Still,
like the idea of a squall line emerging early this afternoon as
activity moving across western ND/NW SD grows upscale and starts
racing along I-94 in ND. We currently anticipate storms to move
into the AXN area between 7-8pm, with storms going across central
MN at the very least this evening. Given the convective mode,
strong winds look to be our main severe threat, with the fast
forward propagation mitigating any excessive rainfall/flash
flooding threats.
&&
.SHORT TERM...(Today and tonight)
Issued at 343 AM CDT Wed Sep 7 2016
Significant heavy rain was ongoing along and south of I-90 as an
area of H925 Fgen, together with 1000 J/kg of MUCAPE and 2" PWATS
remained nearly stationary across northern IA, southern MN, and
central WI. Radar estimates showed nearly 8-10 inches in a few
isolated parts of southeast MN. The reason for this was the cold
front that had slowly sagged southward the last few days was stalled
out as a vigorous upper level trough crossed the High Plains and
headed toward the Dakotas.
This trough caused a more southerly component in the low level flow
ahead of the frontal boundary as opposed to the southwest flow that
previously accompanied this front as it passed through Minnesota.
The end result was an area of Fgen that translated to training
thunderstorms and redevelopment to the south as the storms moved
northeast. HiRes models show this area of convection continuing
through sunrise before slowly dissipating and lifting northward as
the H850 theta_e advection overspreads central MN. For that reason
trimmed back POPs considerably this morning, but then reintroduced
them northward throughout the day. Also trimmed off the northern
extend of the Flood Watch since it is clear that the atmosphere has
set up shop along the MN/WI/IA border.
Additional thunderstorms are expected this afternoon with the height
falls ahead of the aforementioned shortwave trough. SPC has
introduced a slight risk for the northwest part of the forecast
area. Forecast soundings show veering winds and low LCLs so should
have a tornado threat near initiation with these storms. HiRes
models want to congeal the storms into a line and race it across MN,
which makes sense given the strong forcing.
By morning this wave will have driven a cold front through the
region with much cooler and drier weather as dewpoints fall back
into the 50s by sunrise Thursday morning.
.LONG TERM...(Thursday through Tuesday)
Issued at 343 AM CDT Wed Sep 7 2016
The focus for the long term is centered around the system for
Thursday night and Friday, a cold front Monday, and the beginnings
of Autumn-like weather for next week.
Thursday still looks dry area wide following the departure of the
shortwave trough to the northeast away from the Upper Mississippi
Valley. Much drier air will accompany a surface high as it
propagates eastward across the CWA.
The vort/remnants of Hurricane Newton will track northeast and
encounter the tail end of the cold front across the Central Plains
Thursday or Thursday night. This will spawn or maintain an area
of low pressure which will then track south of the CWA Friday.
Convective activity ongoing along the front should reinforce the
southern track thinking. Meanwhile, an approaching longwave
trough digging southeast across the northern Rockies is expected
to lag behind the surface low enough that the two should not phase
before they are well east of the area. That may leave a void in
precip locally, with the tropical, convective rains to the south
and the dry air/weak low level forcing across the northern tier of
states that may generate a few light showers. Reduced pops 10-20
percent across the area, keeping likelies going across the south
and east nearest the southern front/surface low. It should be
noted the NAM/GEM and to some degree the 00Z ECMWF do phase these
features a bit quicker than the GFS, which is the driest
solution.
Dry weather is expected for the weekend with another cold front
sagging southeast across the Plains and Midwest early next week.
Some weak instability/moisture may return ahead of it for a few
storms, but soaking rains are not expected.
Surface high pressure will return following the front with the
chilliest air of the season possible midweek. We are quickly
approaching the climatological normal date for our first lows at
or below 40 degrees (9/8 for STC, 9/10 for EAU, 9/20 for MSP), so
this is nothing unusual.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 458 AM CDT Wed Sep 7 2016
Complex forecast today. An area of showers and thunderstorms will
try to lift north this morning. Then there will be a break, and
another round of storms will move across west central MN and could
affect the northern TAF sites. Low level moisture will hang
around, so expect MVFR/IFR conditions due to clouds.
KMSP...
Area of showers and a few embedded lighting strikes will slowly
lift north and could affect KMSP this morning. Then expect a break
this afternoon, and am optimistic that the storms later this
evening and overnight will be north of KMSP.
/OUTLOOK FOR KMSP/
Fri...Mainly VFR. MVFR in SHRA/TSRA. Winds SE 5-10 kts BCMG SW.
Sat...VFR. Wind NW 10-15 kts.
Sun...VFR. Wind S at 10kt.
&&
.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&
$$
UPDATE...MPG
SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...JRB
Area Forecast Discussion
National Weather Service Marquette MI
733 AM EDT WED SEP 7 2016
.SHORT TERM...(Today and tonight)
Issued at 515 AM EDT WED SEP 7 2016
WV imagery and RAP analysis indicated wsw mid/upper level flow from
the cntrl plains through the wrn Great Lakes between a ridge over
the lower MS valley and a broad trough through the Rockies. At the
surface, a front extended from nrn lower Michigan through cntrl WI
to low pressure over wrn IA. A shortwave trough into ern Nebraska
along with upper level div from the right entrance of a 250-300 mb
jet from cntr Mn into nrn Ontario along with continued strong 850
moisture transport supported an area of tsra from nrn IA into sw and
cntrl WI near the frontal boundary. Other notable upstream
shortwaves were located over sw KS and cntrl Montana.
Today, expect the bulk of the shra/tsra to remain to the south of
the cwa as the convection remains closer to the surface front.
However, radar/satellite trends suggest that some of the pcpn
aided by the broad upper level div is trying to spread to the north.
So, the fcst maintained at least chance pops over Upper Michigan
that will gradually increase from the south to north through the
afternoon.
Tonight, there is uncertainty remaining with the impact of the KS
shortwave on the coverage/location/intensity of the tsra this
evening. There is the potential for some heavier rain in the 1 to 2
inch range over the far south, as a surface wave develops along the
front in response to the shrtwv moving through the region. The
heavier pcpn is expected to shift into the ern cwa by late evening
and overnight. Additional pcpn may devlop from wrn Lake Superior
into wrn Upper Michigan as a shrtwv from the nrn plains lifts
through nrn MN to nw Ontario.
.LONG TERM...(Thursday through Tuesday)
Issued at 526 AM EDT WED SEP 7 2016
Somewhat active zonal flow weather pattern setting up across the
northern CONUS for the end of this week into the middle of next
week.
Thu into early Fri...Models trending drier with Northern Plains
shortwave forecast to move across the region on Thu as associated
best q-vector convergence and deeper moisture generally tends to
stay well of north of Upper Mi into northern Ontario. Track of
shortwave and associated weak forcing would favor northwest Upper Mi
and northern Lake Superior for perhaps light rain in the morning.
Broad mid-upper level ridging and assoc Q-vector
divergence/subsidence in the wake of the shortwave Thu afternoon
will allow for a period of mostly dry weather Thu afternoon into
Friday morning.
Friday afternoon into Saturday...The forecast for this period looks
challenging at this time as model guidance appears split into
generally two camps. The 00Z GFS appears to have backed off from
deeper shortwave/sfc low solution advertised in last night`s runs
while the 00z ECMWF...Canadian and 06Z NAM models still hold on to
stronger and more phased solution developing a deeper sfc low over
northern Lake Mi/eastern Upper Mi Sat morning. Whichever of these
solutions pans out will have a large bearing on forecast. If the 00z
GFS solution pans out developing a weaker sfc low tracking just
southeast of Upper Mi, then the better chance for pcpn would be over
central and eastern counties of U.P. and the west would stay drier.
However, if the deeper and farther nw track of the 00z Canadian and
ECMWF/06z NAM solutions verify this would tend to bring more
widespread rain to the entire area Fri night and develop perhaps a
more defined deformation pcpn band into the western and north
central Upper Mi Sat morning on the nw quadrant of sfc low. Also if
850 temps of 6-7c get pulled across the lake per model guidance
could maybe even see a brief period of lake enhanced rain for
portions of the east half early in the afternoon. A this time will
lean toward deeper solution of 00Z ECMWF/Canadian and 06Z NAM blend
as it is a bit more consistent with 00z runs from last night
although not quite as strong with sfc low. With this stronger
solution depicted by the ECMWF/Canadian/NAM model blend, northwest
winds will get a bit gusty on Sat with tightening gradient behind
deepening sfc low. Models soundings and guidance would suggest the
potential for northwest wind gusts of 25 to maybe as high as 30 mph
across the nrn tier counties with perhaps even some higher gusts
over the eastern half of Lake Superior. Would not be shocked if
there was a period of gale force gusts over eastern Lake Superior
Sat afternoon into early evening.
Ridging and subsidence behind Saturday`s shortwave and
assoc cold frontal passage should result in drier/cooler weather Sat
night into much of Mon. There is plenty of model uncertainty with
timing of next series of shortwaves and their movement along
incoming frontal boundary for late Mon into Wed time frame so will
continue to utilize model consensus low chc pops for next Mon night
into Wed.
Temps should remain near or slightly above normal for Thu and Fri
but should then fall slightly below normal for the weekend in the
wake of the cold fropa Fri night. Dewpoints in the lower to mid 60s
will make it still feel humid on Thu, but then dewpoints should fall
back into the more comfortable 50s range for Fri into early next
week. Both the ECMWF and GFS advertise more fall-like temps for the
middle of the next with 850 mb temps of 2-4C advecting in from south
central Canada in nnw flow by Tue night into Wed time frame. Again
some light lake effect rain off Lake Superior might not be out of
question with this scenario.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 733 AM EDT WED SEP 7 2016
Forecast confidence remains low given variable cloud cover with IFR
to ocnl MVFR cigs persisting through much of the period. The pattern
will be dominated by moist low level ne flow that will upslope into
the TAF sites, especially at SAW where the lower cigs are most
likely. A chance of showers and possibly a thunderstorm will
gradually spread northward from WI but expect the signficant
rainfall and TS prob to reman to the south.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 515 AM EDT WED SEP 7 2016
Winds through tonight are expected to remain mainly at 20 kts or
less. The strongest winds will be Thursday and again on Saturday with
gusts up to 30 knots out of the west on Thursday and out of the north
and northwest on Sat as a deepening low pressure system lifts to the
e of Lake Superior. No gales are expected but cannot rule out gale
potential Saturday if the low pressure trends stronger.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Voss
AVIATION...JLB
MARINE...JLB
Area Forecast Discussion
National Weather Service Norman OK
705 AM CDT WED SEP 7 2016
.AVIATION...
Mid and high clouds will result in VFR ceilings this
morning. MVFR ceilings may still form through the mid
morning but will generally increase into the VFR range
by 16-17Z. Scattered showers and a few thunderstorms
should form by mid to late afternoon, mainly across western
Oklahoma. Any storm will be capable of producing at least MVFR
conditions and gusty winds. A breezy south wind will prevail
through the day.
&&
.PREV DISCUSSION... /issued 348 AM CDT WED SEP 7 2016/
DISCUSSION...
Precipitation over the past several hours has generally been on
the decrease across the Texas Panhandle and northwest Oklahoma.
This trend will likely continue into the first part of Wednesday
as better lift with a shortwave trough moves across Kansas and
Nebraska.
The HRRR and Texas Tech WRF develop showers and storms this
afternoon along a surface boundary that roughly extends from
north of Lubbock into northwest Oklahoma. Overall confidence in
this scenario is not to high. However, another area of convection
near El Paso will continue to move north and east during the day.
Heating along with this "feature" may result in scattered to
widespread precipitation during the afternoon/evening. For now
western and northern Oklahoma will remain in a more favorable area
of showers and storms. A few of the storms in western
Oklahoma/western north Texas may produce locally strong wind gusts
mainly during the afternoon/evening.
A trough or the remains of Newton will keep rain chances fairly
high for western and northern Oklahoma on Thursday. This trough
will approach the southern Plains on Thursday and eventually will
move east of the area by Saturday. This will occur as a fairly
strong trough moves across the Rockies and northern Plains Friday.
An associated cold front will move into northern Oklahoma late
Friday afternoon and should clear southern Oklahoma and northern
Texas by early Saturday morning. Widespread showers and storms are
expected to form along the front with areas of heavy rainfall
possible.
Mainly dry conditions are expected for most of the weekend with
cooler temperatures and drier air.
Another front is expected to move across the area around Tuesday
and Wednesday of next week. Additional showers and storms are
possible with this frontal system.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 93 75 90 74 / 10 20 30 30
Hobart OK 93 74 93 73 / 30 30 30 30
Wichita Falls TX 95 75 95 74 / 10 10 10 20
Gage OK 90 70 93 70 / 40 30 40 30
Ponca City OK 92 74 89 74 / 30 50 50 50
Durant OK 93 75 94 74 / 10 0 10 10
&&
.OUN Watches/Warnings/Advisories...
OK...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
832 AM MST WED SEP 7 2016
.SYNOPSIS...
Deep tropical moisture from hurricane Newton will spread across
central and eastern Arizona today and into the evening hours leading
to widespread showers, some with heavy rain, across areas to the
east of Phoenix. Isolated thunderstorms are also possible. Scattered
showers and thunderstorms will extend westward to around the lower
Colorado River valley today. Newton will move east and out of the
picture later tonight allowing drier air to slowly filter into the
area from the west. By Friday showers or thunderstorms will be
confined to higher terrain areas east of Phoenix. Starting Saturday
and continuing into early next week, monsoon moisture will again
spread into south central Arizona from the south/southwest leading
to a persistent slight chance of afternoon showers and thunderstorms
each day. Mostly sunny skies are expected over the far western
Arizona and southeast California deserts however.
&&
.DISCUSSION...
Tropical Storm Newton continues moving steadily through northern
Sonora this morning with precipitation extending northward into AZ.
Latest Phoenix sounding registered a PWAT of 1.99 inches, which is
the third highest value ever recorded in September. At the surface,
conditions are also quite humid with widespread dewpoints in the
lower 70s.
An outer rain band from Newton moved through portions of southern
Maricopa County this morning, generally producing between a half of
an inch and one inch of rain. The highest rain total observed so far
has been 1.30 inches near Gila Bend. Latest runs of the HRRR continue
to show this band gradually dissipating this morning. Focus will then
shift to the east as light to moderate rain moves northeastward from
southeastern Arizona into Pinal and southern Gila Counties. A Flood
Watch remains in effect for these areas through this evening. Some
adjustments will be made to the forecast this morning, mainly to
refine PoP/QPF/Temperatures.
&&
.PREVIOUS DISCUSSION...
Newton is forecast to reach Arizona as a Tropical Storm and
eventually weaken to depression status as it moves northeast across
southeast Arizona and approaches the New Mexican border near midnight
at a position pretty much due east of Globe. It still appears that
most of the really significant deep tropical moisture will track
across areas well to the southeast of Phoenix and the most
significant flooding issues will stay in Tucson`s domain, but rain in
excess of 1 inch are still very possible across southern Gila County
today, sufficient to lead to flooding or flash flooding issues. We
will continue the Flash Flood Watch for AZZ024 and AZZ028 through 11
pm tonight although confidence in flooding is moderate at this time.
It is nice to see that operational runs from the GFS and ECMWF as
well as most of the GEFS ensemble members have locked in on the
timing and track of Newton so confidence in its movement and where
the primary rains will fall are high. Most likely the lower central
deserts will stay out of the heavier rains; most rainfall totals in
the greater Phoenix area should stay below one half inch. After
midnight tonight, what is left of Newton will continue to push east
and into New Mexico, leaving a more subsident northwest flow aloft to
overspread much of western and central Arizona; this flow will work
to thin out the moisture and as such we are looking at just slight
chances for showers/storms from Phoenix westward during the morning
hours on Thursday.
Drier southwest flow aloft will dominate the weather across
southeast California and Arizona on Friday, leading to mostly sunny
skies over the deserts and warmer high temperatures. The high
temperature in Phoenix Friday is forecast to climb back to the
triple digits with 100 degrees forecast - just barely below seasonal
normal. There may be sufficient lingering moisture over the higher
terrain east of Phoenix to allow isolated afternoon thunderstorms to
form however.
For Saturday into the early part of next week, upper troffing
gradually develops to the west of Phoenix, and the combination of
the southwest flow associated with the trof and flow circulating
around an upper high to our east will allow monsoonal moisture to
spread across portions of south central Arizona. We are not looking
a significant precipitation in the extended period, but will likely
see slight chances for afternoon and early evening storms across
south central Arizona each day with better chances over the higher
terrain east of Phoenix. The far western AZ and southeast CA deserts
should pretty much remain mostly sunny each day with high
temperatures in the triple digits.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Although the circulation center of the remains of hurricane Newton
is still expected to pass well to the south and east of the PHX area
terminals (over extreme SE AZ), cloudiness and showers associated
with this system are still expected to impact the greater Phoenix
area. BKN-OVC cigs in the 8-12 kt foot range, with FEW-SCT layers as
low as 4k foot are expected to prevail through the daytime hours
today before beginning to slowly lift/clear this evening/tonight as
the remains of Newton move off to the east. Scattered shower
activity is forecast to spread into the PHX area during the mid-late
morning hours, with showers becoming more numerous during the midday-
early afternoon hours, when the remains of Newton make their closest
approach, with the shower activity diminishing this evening. Winds
are expected to remain easterly through the taf period, except for a
period of more southerly winds at KPHX and KSDL late this
afternoon/early this evening.
Southeast California/Southwest Arizona including KIPL and KBLH: The
effects of Hurricane Newton (centered over the east coast of
southern Baja Mexico as of 04Z) will primarily be east of southwest
Arizona. However, scattered cumulus and BKN-OVC clouds AOA FL120 can
be expected along with a slight chance of showers this
afternoon/early evening (mainly near and east of the Lower Colorado
River Valley). Southeasterly winds will predominate at KIPL and
southerly winds at KBLH through the taf period.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Friday through Tuesday...
Weak high pressure building into the region from the west is
expected to limit convective activity to just some isolated
showers/storms over the higher terrain east of Phoenix on Friday and
Saturday, and allow temperatures to recover to near, or slightly
above normal values. Another upper trof approaching from the west
will then bring slight chances for showers and thunderstorms to the
lower deserts of South-Central AZ from Sunday into next Tuesday,
with temperatures remaining near normal. Minimum humidities are
expected to remain in the 15-30 percent range through the entire
period, with good-excellent overnight recoveries. Winds to remain
mainly on the light side, except near thunderstorms.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flash Flood Watch until 8 PM MST this evening for AZZ024-028.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...CB
AVIATION...Percha
FIRE WEATHER...Percha
Area Forecast Discussion
National Weather Service Charleston WV
1102 AM EDT WED SEP 7 2016
.SYNOPSIS...
Weakness in the upper ridge allows convection across the northern
tier today. Weak front reaches the Ohio Valley Thursday night.
Stronger front with an airmass change arrives this weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1045 AM...
Increased cloud cover through much of the afternoon across the
north per satellite trends. However...enough breaks to realize max
temps. Kept pops the same.
As of 630 AM...
Still have a persistent cluster of showers over far northern
Randolph and Pocahontas counties at this hours...which the RAP and
HRRR have handled pretty well although the RAP is a tad aggressive
with the showers. No significant changes overall this morning.
As of 220 AM...
Will see an increase in the low level moisture
advection...particularly across the northern tier of counties in
the CWA this afternoon...with the mid and upper levels following
after 18Z. Hi res NAM depicting a weak disturbance riding around
the periphery of the ridge...providing the lift for convection
across north central WV in addition to the diurnal heating. Both
the RAP and HRRR concur with the NAM with the spatial placement of
the convection. Have taken the coverage of the POPs further west
from the previous forecast...into portions of eastern Ohio.
Convection expected to wane during the overnight period.
Given the temperatures yesterday higher than forecast...have kept
the trend of the increased values with prevalent lower 90s over
the Kanawha...Ohio...and Tug Fork valleys.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 245 AM Wednesday...
A cold front approaches from the northwest Thursday, slowly moving
east and spreading showers or storms Thursday night into Friday.
Bufkit soundings show thin CAPE feature with equilibrium level
exceeding 40 kfeet. So, expect tall thunderstorms ahead and along
the front. This front should then begin to pull back north as a
warm front late Friday...in response to an area of low pressure
approaching from the west.
Above normal temperatures with muggy conditions return through
Friday night. Went closer to the NAM and super blend numbers for
temperatures through the period.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 823 AM Tuesday...
Went with WPC thinking with some tweaks. A stronger cold front is
expected to push southeast Saturday into Saturday night with showers
and storms. There could also be a few showers in the mountains early
Sunday. High pressure will then build in during the day on Sunday
and continue in control of our weather through Monday night.
Temperatures should be close to normal values on Sunday and Monday...
before warming back up for Tuesday.
Chances for showers and storms will return on Tuesday as moisture
returns and a system approaches from the west.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
15Z Wednesday to 15Z Thursday...
Introduced MVFR ceilings mainly across the higher elevations of
the northern mountains til 18z...at EKN til 16z. mixing will then
lift ceilings to VFR.
Previous earl;y morning discussion...
Prevailing VFR with more vertical extent to the cumulus formation
today...especially from CKB to EKN where isolated to scattered
SHRA/TSRA are possible. Surface winds below 10kts...except from
EKN to BKW where the occasional gust to 15kts is possible.
Leaving fog out of the forecast again tonight...however...rain at
any terminal may need fog added in to the forecast.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY...
FORECAST CONFIDENCE: High.
ALTERNATE SCENARIOS: May need TEMPO SHRA/TSRA at EKN/CKB later
today...after 18Z.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 15 16 17 18 19 20 21 22 23 00 01 02
EDT 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
CRW CONSISTENCY L L L L L L L L L L L L
HTS CONSISTENCY L L L L L L L L L L L L
BKW CONSISTENCY L L L L L L L L L L L L
EKN CONSISTENCY L L L L L L L L L L L L
PKB CONSISTENCY L L L L L L L L L L L L
CKB CONSISTENCY L L L L L L L L L L L L
AFTER 12Z THURSDAY...
Isolated IFR possible in showers/storms through Saturday. IFR
possible in overnight valley fog for terminals that receive rain.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...ARJ/26
NEAR TERM...JSH/26
SHORT TERM...ARJ
LONG TERM...JSH
AVIATION...JMV/26
Area Forecast Discussion
National Weather Service Blacksburg VA
928 AM EDT Wed Sep 7 2016
.SYNOPSIS...
A weak disturbance will drop south into the region today before
stronger high pressure builds back into the area from the
southwest for the end of the week. A cold front will move into and
through the region Saturday night into Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 928 AM EDT Wednesday...
Northwest flow will continue aloft as we remain between the remnant
Hermine low pressure along the mid-Atlantic coast and upper
ridging to the southwest. A weak shortwave dropping southward this
morning sparked a few showers in the east. However, this activity
is weakening and dissipating with time. Another weak impulse and
associated speed max aloft will drop south this afternoon across
eastern portions of the forecast area. The Hiresw-arw-east, RNK
WRFarw, and HRRR support the mention of isolated storms in the
northeast and east this afternoon. However, most of the convection
will be to our east this afternoon into this evening. For this
morning update, adjusted temperatures with sfc obs and blended
toward lamp guidance for late morning into this afternoon. It will
be another hot day with high temperatures from lower 80s in the
mountains to the mid 90s in the Piedmont. More changes late
today...
As of 245 AM EDT Wednesday...
Area remains in a blocked pattern under northwest flow aloft between
the remnant Hermine low along the mid-Atlantic coast and upper ridging
to the southwest. Faint moisture channel sliding into the region
from the north around the back of Hermine as seen via vapor loop,
the main concern today in regards to possible convective
development espcly northeast sections. Models also suggest that a
weak impulse and associated speed max aloft will drop south along
this convergence axis during max heating. This mainly just east of
the CWA along a progged corridor of 850 mb theta-e ridging and
where an axis of moist PWATS will develop within CAPE values of
better than 1500 J/KG. Some guidance including the latest HRRRX
and NCAR Cam solutions also show spotty showers this morning
north/east of LYH, then redevelop at least isolated shra/tsra
along the LWB-HSP-LYH-W78 corridor and points east this
afternoon. This perhaps a bit overdone given deep northerly flow
that will gradually veer westerly and dry air aloft. However with
return of higher dewpoints, plan to include some low chance pops
mainly north/east, with a token shra mention as well far west as
low level westerly convergence develops. Otherwise appears enough
ridging aloft extending out of the TN valley to limit coverage
overall given best forcing/moisture to the east. Thus expect some
clouds early, then partly/mostly sunny and hot with highs 80s west
to low 90s east, per more of a downsloping trajectory this
afternoon.
Should see most convection slide east of the area this evening with
ridging aloft strengthening from the southwest in wake of the passing
impulse this evening. This will lead to mainly clear skies with
patchy fog after midnight with perhaps the east hanging onto a bit
more debris clouds until late. Lows basically persistence with
mostly 60s except only around 70 in elevated spots.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY/...
As of 230 AM EDT Wednesday...
An upper level ridge, centered over the southern Mississippi Valley
stretching northeast over the Tennessee Valley and southern
Appalachains mountains, will gradually shift east over the next
couple of days. While this ridge is over the area, warmer than
normal temperatures can be expected with mid to upper 80s west and
low to mid 90s east.
Scattered showers and thunderstorms are possible each afternoon
across the mountains. With a weak lee trough over the piedmont, a
few isolated storms may develop east of the Blue Ridge late in the
afternoon and early evening.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
As of 310 PM EDT Tuesday...
Timing of the next significant front still on Saturday night into
Sunday on the latest guidance. Moisture along this front Sunday
night through Monday remains over North Carolina while drier air
comes into the north. The coolest night behind the front will be
Sunday night. Stayed close to guidance which was trending lower for
minimum temperatures. High pressure behind the front Sunday night
will move offshore on Monday.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
As of 640 AM EDT Wednesday...
Fog remains limited across the region early this morning due to
cloud cover in spots as well as lack of saturation per current
spread in temps/dewpoints attm. Thus will likely reduce fog
coverage in the valleys pending release coverage with VFR most
spots to start under pockets of mid deck and strato-cu.
Otherwise expecting overall VFR conditions to prevail for most of
the region through the valid TAF period. A weak disturbance on
the west side of the remnants of Hermine will head south into
eastern sections of the region this afternoon. Isolated showers
will be possible this morning in far northern parts of the area,
with the best chances in the afternoon with isolated thunderstorms
possible mainly northern/eastern sections. However, not expecting
enough coverage at any of the terminals to warrant mention in the
forecast, with KLYH possibly the closest. Therefore mainly
looking at VFR scattered/broken cumulus and broken mid deck
at times through the afternoon.
Appears any convection will track to the southeast and end across
the east early this evening followed by mainly clear skies and
light winds. Should see a bit more in the way of fog overnight
given clearing and increasing moisture with potential for all
locations excluding KBLF/KROA to see a period of sub-VFR toward
daybreak Thursday. Appears KLWB could drop to LIFR late with KBCB
IFR to MVFR as well.
Extended aviation discussion...
The vast majority of the period through Sunday will be VFR.
Moisture will increase through late in the week in advance of a
weak cold front that should remain to the north Thursday into
Friday. This boundary may prompt some isolated to scattered
showers and storms, primarily during the heating of the day on
Friday. A few of the stronger ones of these could produce some
temporary sub-VFR conditions. Late night and early morning river
and valley fog will also be possible.
A more substantial front is slated to move into the area Saturday
night into Sunday. Some localized sub-VFR ceiling may accompany
this feature along with better organization of showers. Models
however do not offer a lot of hope that the activity will survive
the trip east of the Blue Ridge at this point.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...DS/JH
NEAR TERM...JH/KK
SHORT TERM...RCS
LONG TERM...AMS/RCS
AVIATION...DS/JH/WP
Area Forecast Discussion
National Weather Service Shreveport LA
1104 AM CDT WED SEP 7 2016
.DISCUSSION...
The morning water vapor imagery indicates broad upper ridging
anchored over the Srn Plains and lower MS Valley...with the
visible satellite depicting cu towers now developing over the
Delta region of SE AR/NE LA where the ridge is weakest. A step
outside in the parking lot reveals the cu field still flat as of
late morning closer to the ridge center over NW LA...with temps
having warmed already to the upper 80s over much of NW/Ncntrl LA
as of 1550Z. Isolated convection has recently developed with the
weak seabreeze over extreme SE TX/SW LA...but this should not
advance too far inland given the very weak Srly flow beneath the
ridge. Thus...believe that convection will be more isolated this
afternoon along the Ern edge of the ridge center...mainly over
Deep E TX/N LA/portions of SW AR as suggested by the lastest HRRR
and 12Z NAM.
Have updated the forecast to lower pops to slight chance this
afternoon for the aforementioned areas...and also lowered sky
conditions to partly cloudy as the cu field should remain mostly
scattered. Have also made minor adjustments to max temps and
dewpoints this afternoon to reflect current obs and expected
trends...with dewpoints likely not mixing out much for the
afternoon. This will result in heat indices nearing 105 degrees
over N LA...but will hold off on a Heat Advisory for now for this
area.
Zone update already out...grids will be available shortly.
15
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 94 75 93 75 / 20 10 10 10
MLU 93 74 93 72 / 20 10 10 10
DEQ 93 72 93 73 / 10 10 10 10
TXK 94 75 93 75 / 20 10 10 10
ELD 92 74 93 73 / 20 10 10 10
TYR 93 75 93 75 / 10 10 10 10
GGG 94 75 93 75 / 20 10 10 10
LFK 93 75 94 75 / 20 10 20 10
&&
.SHV Watches/Warnings/Advisories...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
15
Area Forecast Discussion
National Weather Service Tucson AZ
904 AM MST WED SEP 7 2016
.SYNOPSIS...Tropical Storm Newton will move through the area today,
weakening as it moves north but not before bringing widespread
rainfall and breezy winds to the area. The showers will diminish
rapidly this evening as storm moves off to the northeast with
lingering moisture maintaining a few thunderstorms Thursday and
again later in the weekend.
&&
.DISCUSSION...
Tropical Storm Newton continues to quickly move through Mexico this
morning with a 15Z position about 70 miles south of Nogales, AZ.
Stratiform rain continues to overspread southeast Arizona although a
few lightning strikes were noted across far western Pima Co. Thus
far precip totals have been on the order of a half inch to an inch
in the lower elevations with higher amounts (2+ inches) in the
higher terrain of Cochise and Santa Cruz Co`s, although some higher
amounts have been observed in Nogales, Mex. At this point it`s
questionable if it will retain Tropical Storm strength as it crosses
into the Arizona. Will need to hunt around for strong enough winds
once it enters the state before determining it`s status as the first
Tropical Storm in the state since Nora in 1997.
The only area of concern so far is elevated flow along Nogales Wash
as well as washes in the Huachuca Mtns. Flooding elsewhere has been
minor and relatively insignificant (mostly poor drainage areas). In
terms of rain rates, they have steadily increased and are generally
on the order of 0.25-0.50 inches per hour. Normally this wouldn`t be
anything to be too concerned about but radar indicates there is
still quite a bit of precip south of the border heading our way.
Efficient warm rain processes will dominate in a tropical
environment and as such, there will be a continued threat of
flooding across the area. Latest few runs of the HRRR suggest the
stratiform rain will migrate north of the border and through Tucson
shortly before noon and given current rain rates, it`s conceivable
that we could see an additional 0.5-1.0 inches of rain area-wide
through noon. Looking ahead into the afternoon hours, things get a
bit more tricky. There is quite an extensive cloud shield extending
through Sonora into the Gulf of California and it could very well
stay overcast all day. However if a few breaks develop (as the HRRR
and HRRRx are suggesting), convection could develop later in the
afternoon hours. I`m going to leave the Flash Flood Watch in effect
unchanged and retain elevated PoPs across the area through at least
early evening to give the stratiform rain sufficient time to exit
the area, as well as to give storms a chance to develop and
dissipate if we get clearing. Otherwise the precip portion of the
forecast looks on track.
I did make an adjustment to the winds and have replaced the High
Wind Watch with a Wind Advisory for the mountains along the US/Mex
border. While we have seen one location gusting into the upper
60+mph range, it has a favorable east exposure all other sites are
well below High Wind criteria. Winds will certainly be breezy today
and should reach their peak by early afternoon, but should remain in
the 25G35-40KT range.
&&
.AVIATION...Valid thru 08/12Z.
Scattered to numerous -SHRA with embedded isold TSRA thru 08/04z
as remains of Tropical Storm Newton impacts the area. Cloud decks
mostly 6-10k ft agl. Locally heavy rain and MVFR CIGS/VSBY is likely
with stronger cells. Conditions slowly improving from W to E aft
08/05z.
Surface winds will continue to be on the incr thru 07/23z as the
circulation reflection of Newton pushes into the area aft 07/16z.
Strongest winds are expected to occur across Santa Cruz and srn
Cochise counties. Looks for sustained winds of 20 to 30 kts with
gusts to 40 kts will primarily affect the KOLS and KFHU with less
wind at KTUS. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Showers and isolated thunderstorms will be around
today as the remnants of Tropical storm Newton pushes across the
area. Strong winds of 20 to 30 mph with gusts to 40 mph will also be
an issue this morning and afternoon, especially near the Int`l
Border. Lingering moisture will result in a slight chance of showers
and thunderstorms Friday into Sunday, with 20-ft winds returning to
their normal diurnal trends.
&&
.CLIMATE...The lowest maximum daytime temperature on record for
Tucson International Airport today, September 7, is 77 degrees set
in 1919. At midnight it was 77 degrees and dropping and provided we
don`t rise above 77 the remainder of the day we will have tied the
old 97 year old record. The maximum recorded rainfall for Tucson
International Airport on Wednesday, September 7, is 1.15 inches set
in 2006.
&&
.PREV DISCUSSION...
Once Newton slips off to the northeast the shower and storm activity
will trail off quickly this evening. Without significant flow to
clear out the moisture tomorrow would expect the sun to work on the
moist air mass and trigger scattered convection Thursday around the
area. This is covered well in the current forecast. Temperatures
Thursday will rebound significantly from the near record "cool"
conditions today but will still remain a bit below normal.
Friday into Saturday a 590+ 500 mb high over the area will allow
afternoon temps to climb further to above normal levels again and
should suppress convection across the area thus I went for a mostly
dry forecast for those two days and tweaked temps up a couple of
degrees. May see another 100 in Tucson before we put that to bed.
By Sunday, an upper level trough is begining to develop along the
west coast while the high slips to the east which will allow for a
return flow of some moisture and scattered convection Sunday onward.
This will also allow afternoon temperatures to gradually trend down
once again back to seasonal norms.
&&
.TWC Watches/Warnings/Advisories...
Flash Flood Watch until 8 PM MST this evening for AZZ502>515.
Wind Advisory until 5 PM MST this afternoon for AZZ503-504-507-
508-512>515
&&
$$
PUBLIC...Leins/Cerniglia
AVIATION....Glueck
FIRE WEATHER...Glueck
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Wakefield VA
440 PM EDT WED SEP 7 2016
.SYNOPSIS...
A trough of low pressure remains over the local area through
tonight. Post tropical cyclone Hermine weakens and finally begins to
push away from the coast Thursday. Meanwhile, high pressure resides
over the Southeast states through the end of the work week. A cold
front reaches the local area Sunday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Latest GOES water vapor imagery centers the stubborn upper low
offshore of the Mid-Atlantic coast this afternoon. A narrow band of
high precipitable water remains over the region, between the
building upper ridge and the offshore low. At the surface, a
lee/thermal trough remains over the Piedmont. Breaks in the cloud
cover this afternoon has allowed temperatures to warm into the 80`s
to low 90`s. Instability has also increased, with RAP mesoanalysis
depicting 1000-1500 J/kg of MLCAPE from the Peninsula northward to
northern Virgina. A few showers and thunderstorms have developed in
the moist/unstable air mass over the Northern Neck and middle
Peninsula. Expect only isolated to scattered showers and
thunderstorms through mid afternoon. Thereafter, an upstream wave
associated with convection over southwest Pennsylvania will drop
into the region late today and this evening. Expect another round of
scattered showers and thunderstorms generally from the Piedmont to
the Bay. Guidance indicates the best chances will be this evening.
Main impacts will be locally heavy rainfall due to high freezing
levels/deep warm layer. Showalter values remain negative (upper
level instability) through the overnight, which could allow some
showers to linger along the sfc trough through late tonight. Some
clearing is possible late tonight for the Piedmont, which could lead
to patchy shallow/ground fog. Otherwise, cloud cover will limit any
fog development. Mild tonight, with lows in the low to mid 70`s.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
The next northern stream shortwave traverses the Great Lakes region
Thursday. The upper low associated with post tropical cyclone
Hermine opens and ejects northeast ahead of the shortwave. Surface
low pressure lifts along the Saint Lawrence River Valley, with a
trailing cold front extending southwestward into the Midwest. The
lee trough sharpens Thursday thanks to stronger pressure fails ahead
of the front. Surface high pressure pushes offshore. Return flow and
850mb temps warming to 20+C (+1 to +2 standard deviations) will
result in a warm afternoon. Highs forecast in the low to mid 90`s.
Several record temperatures may be challenged. Heat indices will be
around 100 degrees. Sky will average partly cloudy, which will help
keep temperatures from reaching the higher NAM/MET guidance. Will
maintain a dry forecast as the ridge axis builds overhead. Models
and soundings still indicate relatively high relative humidity in
the mid levels Thursday night, so will retain a mostly clear sky
inland to partly cloudy near the coast. Mild, with lows generally in
the low to mid 70`s.
Surface low pressure locates over the Canadian maritimes Friday as
the attendant cold front reaches the northern Mid-Atlantic region.
The front stalls as heights build over the local area. Another warm
day in store with temperatures back into the low to mid 90`s. Heat
indices back around 100. Best chances for precip will be north of
the local area along the frontal boundary. With anomalous heights
over the region, it will be difficult to get measurable precip even
into the Delmarva. Mild Friday night with lows in the low to mid
70`s under a mostly clear to partly cloudy sky.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The longer term models are in decent agreement overall showing
the southeastern US ridge briefly breaking down on Sunday as
shortwave trough in the generally westerly flow slides through the
eastern US before the ridge rebuilds through the first half of
next week. The GFS seems to be the most aggressive attempting to
break down the ridge and also faster with the movement of features
through the westerly flow over the northern half of the country.
The ECMWF however, allows the ridge to rebuild and thus is slower
with the movement of the features through the westerly flow.
Overall the pattern has been over the last few months for the
ridge to be strong and persist so have trended the forecast in
that direction toward the ECMWF.
So have kept the weather dry and warm on Saturday, but an isolated
thunderstorm is possible just due to the heating of the day. The
cold front arrives on Sunday as the ridge breaks down. The best
forcing and moisture is north of the area, leaving only the
frontal surface forcing for lift and with the east to west flow,
expect the moisture to be limited so think the best chance for
rain will be in eastern portions of the area. But even there the
chance are not very good. The front should clear the area...but it
will not be too far to the south however, stalling over northern
North Carolina.
The dry weather then returns for Monday through Wednesday as the
upper ridge rebuilds. On the bottom side of the sfc high, the
easterly flow will allow some Atlantic moisture to return. This
may allow for some scattered convection near the stalled front.
Temperatures will drop back into the 80s early next week, but
expect them to gradually increase each day back toward 90 by
Wednesday.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
VFR conditions have returned to the local area in wake of this
mornings convection. Lingering mid level clouds expected through
mid afternoon as another disturbance drops into the region.
Isolated showers and thunderstorms are possible across the
northeast local area mid to late afternoon through this evening.
Main impacts will be locally heavy rainfall and gusty winds.
Confidence is not high for impacts at the TAF sites, so have left
out of 18Z issuance. Otherwise, surface winds west to northwest at
or below 10 knots. Expect a scattered to broken deck at 5 to 8K
feet AGL through the overnight. Guidance continues to indicate fog
late tonight, but based on persistence and a lack of
precipitation outside of KRIC and KECG, expect only patchy
shallow/ground fog over the Piedmont where clouds expected to
clear late.
OUTLOOK...High pressure/fair weather prevails during most of the
period thru Sat. A cold front reaches the region late Saturday
night with a chance of showers/thunderstorms Sunday afternoon.
&&
.MARINE...
The weather across the region continues to quiet down as The
remnants of Hermine continue to slowly spin off the NJ coast. This
feature will slowly begin to get pushed off to the NE on Thursday
ahead of an approaching cold front. As the surface low weakens,
the sfc flow over the waters continues to turn to more wsw to sw
and gradually more southerly on Thursday. With the weakening
winds, the seas will also continue to diminish.
The upper level ridge will hold the approaching cold front at bay,
stalling it near the Mason Dixon line so expect the sw flow to
continue Friday into Sunday afternoon, when a cold front will
slide through the waters. Behind the front should see a period of
northerly flow that could produce winds of 15 to near 20 kt. If
any period in the next 5 day could reach small craft it would be
this time Sunday evening into Monday. But for now, it does not
appear to be enough cold air behind this front to get the winds up
enough to reach SCA. High pressure builds in early next week with
light winds.
&&
.CLIMATE...
Near record high temperatures are forecast for Thursday 9/8.
Record Highs for September 8th
* Richmond: 97 (1954)
* Norfolk: 96 (1985)
* Salisbury: 94 (1985)
* Elizabeth Cty: 94 (1983)
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.
&&
$$
SYNOPSIS...SAM
NEAR TERM...SAM
SHORT TERM...SAM
LONG TERM...ESS
AVIATION...MAM/SAM
MARINE...ESS
TIDES/COASTAL FLOODING...
CLIMATE...
Area Forecast Discussion
National Weather Service Gaylord MI
403 PM EDT WED SEP 7 2016
.SHORT TERM...(This evening and overnight)
Issued at 309 PM EDT Wed Sep 7 2016
High Impact Weather: Possible Heavy rain tonight.
Weak sfc trough is stretched out across the region with a jet
streak of 50 knots moving through the region as well. Rain on the
radar has been continuing to trend downward for most of the
afternoon, with only some small areas of development on KAPX radar
with the last 1/2 hour. Main rain/thunder action has been along
and south of US-10 corridor outside of the forecast area. This has
made the forecast a challenge, as the showers/thunderstorms
downstate have been pushing the cold pool south inhibiting the
triggering of convection along the weak sfc trough/front.
Tonight...as mentioned earlier in an update, the model spread of
where/when the rain will begin to redevelop has been vast. The
GFS/ECMWF ideas of rain widespread across the forecast area late
this afternoon/early this evening with the front/sfc trough then
pushing south and east by 12z. Looking at the NAM12, it does have
some sort of convective feedback area, on it, but generally is in
line with the GFS/ECMWF idea, as is the 18z/RAP13 model. The
HiRes models (ARW and NMM) both have a southern start to the rain
before developing heavy rain in the Straits region overnight.
Although the NMM does have rain spread liberally across the
forecast area somewhat like the GFS/ECMWF idea. The HRRR is along
the lines of the ARW.
So have tried to take some sort of consensus forecast overnight
with the rain developing and moving into the region around 00z and
continuing across the forecast area through 06z. Then the dry air
beginning to move into the region after 06z as the cold front
pushes the rain out of the region by Thursday morning.
Thursday...Large nose of 700-500 mb layer dry air pushes into the
Upper Great Lakes after 12z. The ECMWF is a little more vigorous
with the QPF over the region with light, scattered showers through
the morning while the GFS, actually stops raining. The after is
dry on both models and the NAM as well. So have been scaling back
the pops and drying out the afternoon.
.LONG TERM...(Thursday through Wednesday)
Issued at 309 PM EDT Wed Sep 7 2016
High impact weather potential: Another round of heavier rain.
Pool of deeper moisture south of the cold front starts to return
late Friday as upper trough moves into the northern Midwest. Frontal
system strengthens as it moves into the Great Lakes and LLJ develops
out ahead. Surface low forecast to move over northern MI late
Friday/early Saturday. Not much instability forecast this far north
but right entrance region of upper jet and LLJ move overhead Friday
night with PWATs between 1.5" and 2.0". With plenty of moisture and
lift over northern MI expect another descent bout of rainfall. Even
though surface low moves quickly through the region...upper trough
lags so not looking for much improvement during the day Saturday.
Farina
Extended (Saturday night through Wednesday)...
High pressure looks to quickly usher any lingering precip well east
of the area Saturday night. Mostly sunny skies, light winds and
gradually moderating temperatures are expected for the end of the
weekend into the start of next week prior to another cold front
arriving during the Tuesday-Wednesday timeframe, bringing scattered
showers and perhaps a few rumbles of thunder. Another expansive area
of high pressure settles atop the heart of the country for the tail
end of the next work week.
Gillen
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 149 PM EDT Wed Sep 7 2016
Difficult forecast with low confidence on the evolution of this
system. As rain has been heading into N Lower, the rain has been
falling apart, but with CIGS VFR, with occasional MVFR. Models
have been indicating that the CIGS and VSBYS will be lowering
this evening with rain and possibly thunderstorms as the cold
front and sfc low moves through the region. With the fairly humid
air mass, will expect that the CIGS will fall to IFR and possibly
LIFR categories through about 12z overnight. CIGS and VSBYS will
improve after 12z, probably both becoming VFR again as the rain
leaves the region.
&&
.MARINE...
Issued at 309 PM EDT Wed Sep 7 2016
Tonight through Friday...Winds will start off light and variable
as the low begins to develop in eastern Iowa. However, as the low
moves toward the Upper Great Lakes, the winds will begin to
increase overnight, but looks to remain below small craft
criteria. Thursday, the winds will shift to the west and relax for
a bit as a sfc high begins to move into the Upper Mississippi
Valley. Thursday night, the high will build into the State,
causing the winds to be light and variable again. Friday, the
winds will begin to increase out of the south west again as the
sfc high moves to the Lower Great Lakes and Michigan gets into the
return flow.
&&
.APX Watches/Warnings/Advisories...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
SHORT TERM...JSL
LONG TERM...Gillen/Farina
AVIATION...JSL
MARINE...JSL
Area Forecast Discussion
National Weather Service La Crosse WI
307 PM CDT WED SEP 7 2016
.SHORT TERM...(This evening through Thursday)
Issued at 305 PM CDT Wed Sep 7 2016
Flooding threat looks to have taken a step down, certainly
compared to last night. Areas that did not see too much rain last
night look to be the receivers through the evening.
Main focus is really on the next 12 hours across the area with
radar indicating next wave of rain quickly approaching.
Instability for heavier rainfall rates (MUCAPE over 1000 J/Kg)
really confined to the southernmost forecast area per SPC
mesoanalysis at 19z - southern WI and adjacent IA counties on Miss
River. Moisture transport increases into and ahead of the wave
now over eastern IA coming in per RAP forecasts, and into the
evening. Thus, we should see an uptick in showers across the area
overall with this wave, with the strongest storms over that
southernmost area.
The latest RAP guidance suggests that the low-level moisture
transport will quickly veer to the east with even westerly 850 mb
flow occurring over the southern forecast area by 7 pm. This
suggestion is supported in many of the models with a quick drying
after this one-and-done wave of rain through early evening. If
this is the case, and it seems legit with current observations, it
is easy to see why the flooding threat has diminished across at
least the flood watch area. Forecast amounts of closer to 1-2"
look to be the upper estimates by 7 pm, with soils able to handle
that amount.
Will keep the Flood Watch for this far southern area to keep
collaborated with the neighbors and for rain, but the remaining
Watch could probably be expired early this evening (see codes
below for remaining area).
Water vapor showing a strong shortwave trough over the Dakotas at
this time and a quick recovery in CAPE has been occurring in
western MN and eastern SD today. This all ahead of the surface
cold front that will eventually make its way into the area
Saturday (dewpoint relief!). This is upscaling the convection
associated with that strong trough forcing in the Dakotas. Latest
trends in the CAMs bring a convective line through MN tonight
and 30-50 percent small chance of thunderstorms north of I-90
tonight, but CAPE should be waning during the overnight hours and
the QG forcing is lifting strongly northeast.
.LONG TERM...(Thursday night through Wednesday)
Issued at 305 PM CDT Wed Sep 7 2016
Thursday night through Friday night...Rapid return flow ahead of a
strong shortwave trough entering the Dakotas Thursday night will
bring the chance for storms to the area again into Friday morning.
Then...the main trough moves in with a cold frontal passage
Friday afternoon. Pretty impressive mid-level lapse rates Friday
above 7C and a straight line supercell shear hodograph means it
could be interesting. The biggest limiting factor /also mentioned
in the spc day 3 outlook/ is clouds and building instability.
Should this instability grow Friday afternoon, severe weather is
likely and another 1" of rain could occur. So, for now it is a
conditional threat, on the condition that instability develops.
Plan to update the Haz Weather Outlook to include a bit more
threat Friday. There could be an isolated severe threat Thursday
night with return flow - mainly large hail - should instability
return be large enough.
Saturday through Wednesday looks to be a cooler and drier period
with northwest flow dominant. However, some differences occur for
next week in the evolution of a large scale trough in the western
U.S. in the model guidance. We are hoping this doesnt turn into a
prolonged southwest flow regime and rainier pattern again.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1229 PM CDT Wed Sep 7 2016
Back edge of overnight/morning convection edging eastward into
central WI. Another batch of shra/ts on its way across central IA.
Looks like the main brunt of this will stay south of the KRST/KLSE
TAF sites. Opted to keep VCSH at KRST while bring a period of 3sm
shra into KLSE in the 20-22z time frame. Otherwise...looks to stay
predominately MVFR into this evening. Concern then shifts to ifr fog
overnight/early Thursday morning (06z-14z) given very damp lower
boundary layer and no good push of drier air. Should pick up a
westerly breeze after sunrise which should help to diminish
fog/stratus.
&&
.HYDROLOGY...
Issued at 305 PM CDT Wed Sep 7 2016
The Upper Iowa and Kickapoo river basins were hardest hit of the
bunch overnight and will see mainly minor flooding. However, many
secondary roads are still closed in Richland and Vernon counties with
water over the roads in Richland still. Iowa and Minnesota seem
to be more improved with no water over roads. will reissue the
areal flood warning for the richland/crawford/vernon county area
overnight.
&&
.ARX Watches/Warnings/Advisories...
WI...Flood Watch until 1 AM CDT Thursday for WIZ053>055-061.
MN...None.
IA...Flood Watch until 1 AM CDT Thursday for IAZ011-029-030.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...DAS
HYDROLOGY...BAUMGARDT
Area Forecast Discussion
National Weather Service State College PA
353 PM EDT WED SEP 7 2016
.SYNOPSIS...
Hermine will linger off the coast today. The strong ridge aloft
over the MS/OH valleys will weaken a bit as storms break over the
ridge. Muggy air will stick around until a cold front passes
through this weekend. After a day or two of seasonable
temperatures Sunday and Monday another warm-up will occur.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Finally can see some organized convection to our west in southwest
PA and a lone shower in southern Franklin County. See if the next
HRRR cycle picks up on the southwestern storms and their potential
evolution.
Looks like most of northern and northeastern areas are free of
convection for now. Farther east is closer to the dry air on WV
imagery.
Temperatures mainly in the 80s.
The HRRR favors some convection across various area over the next
2-8 hours but has under done the convection to the west. The
signal is for scattered convection sans the more organized line to
the west later this afternoon and evening. RAP and HRRR CAPE favor
west and central areas of best convection.
High dewpoints and light winds favor overnight fog and haze.
Thicker where the rain may fall. Kept POPS mostly chance and
slight chance with some texture based on the HRRR forecasts.
Very warm overnight for September.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Potential for lingering convection in morning in south-central PA.
Key signal tomorrow is simple hazy, hot, and humid. The 850 hPa
temperatures peak over 20C over portions of east-central PA with
widespread values of 18C over nearly all of PA.
The larger scale models imply all overnight convection is over
Thursday AM and most of the day is dry. But the GEFS and other
models imply new convection could develop in west/northwestern
areas in the afternoon and early evening. Kept highest POPS in
afternoon in that region.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
In generall, heights are forecast to be rising over the Eastern
U.S. early in the period ahead of a mid-scale trof
developing/digging over the northern Plains. This trof is forecast
to swing through the Northeast and northern Mid Atlantic regions
over the weekend, with the subtropical ridge rebuilding early next
week.
Within the generally rising heights, multiple shortwaves will move eastward
across the northern tier of the CONUS...bringing an increase in
the chances for showers/thunderstorms Thursday and Friday. The
above mentioned Northern Plains trof and associated surface cold
front is advertised for later Saturday into early Sunday. This
should support the hiest chances of pcpn during the period.
Behind the front, a return to dry weather is in store. It will
be noticeably cooler on Monday, but then turn warm again Tuesday
and Wednesday as the upper ridge rebuilds northward.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
Mostly VFR today though some patchy areas of MVFR due to haze.
Expect more haze tomorrow. Overnight haze and patchy fog will
provide widespread MVFR and locally IFR conditions. The haze will
linger Thursday with widespread areas of MVFR/VFR.
This afternoon we have a line of showers and thunderstorms in
southwestern PA which will move to the south-southeast. This
first batch should pass near KJST and KAOO and south. Isolated
showers could pop up over most of south central Pennsylvania this
afternoon and evening. Most of those have been short-lived and
keep moving to the south-southeast.
Storms will lower cigs and visibility and produce gusty winds.
Check radar before takeoff.
Outlook...
Thu...Patchy AM fog likely. Isold PM tsra impacts possible,
mainly southwest-south central areas.
Fri...AM low cigs possible w mtns.
Sat...Isold PM tsra impacts possible, mainly w mtns.
Sun...AM log cigs possible w mtns.
&&
.CLIMATE...
Records today: IPT=95 and MDT=96.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Dangelo
NEAR TERM...Grumm
SHORT TERM...Grumm
LONG TERM...La Corte/Gartner
AVIATION...Grumm
CLIMATE...
Area Forecast Discussion
National Weather Service Des Moines IA
407 PM CDT Wed Sep 7 2016
.SHORT TERM.../Tonight/
Issued at 406 PM CDT Wed Sep 7 2016
.Tonight...Lingering showers and thunderstorms and the potential for
fog development were the main focus tonight. Surface boundary still
remains across southern Minnesota into northwest Iowa and extends
west through central Nebraska. The 07.18z and 07.19z HRRR have a
good handle on convective trends this afternoon into tonight. The
heavy rain threat still exist over the eastern to southeast portions
of the forecast area tonight where the better moisture convergence
and forcing for ascent is located. Plenty of moisture remains in the
atmosphere ahead of the frontal boundary slated to push through the
CWA between 03-09z tonight. PWATs near 2.0 inches, warm layer cloud
depths approaching 4000-4500 meters, and decent moisture transport
persist over the east-southeast sections of the CWA through at least
03z Thursday. Expanded the flash flood watch a tier of counties
south and kept it going as far north as Waterloo. Further west and
north, not anticipated much additional heavy rain this evening. Fog
looks possible across the north in the location of the heavy rain
last night. Inversion looks to develop by 09z Thursday as the
surface high builds into the state providing enough clearing to
allow for radiational cooling to cause some patchy fog.
.LONG TERM.../Thursday through Wednesday/
Issued at 406 PM CDT Wed Sep 7 2016
Precipitation is expected to move south of the the area by
Thursday morning as much drier air arrives with high pressure
moving in from the west. High temperatures will be in the 70s
north to low to mid 80s south. Thursday evening through Friday
central Iowa will have the potential to be impacted by 2 systems.
The first is the remnants of Hurricane Newton and the other is a
strong short wave trough moving into from the northwest. Return
flow and strong theta-e advection will begin lifting back into
western Iowa Thursday evening and as this occurs moisture
associated with Newton will begin to arrive. The trough
approaching from the west and a cold front at the surface will have
an impact how far northwest the remnants of Newton are able to
get. Thunderstorms are expected over southeast Iowa with the
moisture from the south and additional storms over the northwest
half of the state along the boundary and upper level trough
arrival. The activity to the northwest will spread south/southeast
through the day and evening as the upper wave arrives. A few
severe storms and heavy rainfall will again be possible especially
during the afternoon and evening hours as the strongest forcing
arrives. The primary severe weather threat will be damaging wind
gusts. PWAT values again will be over 2 inches. Storm motions will
be parallel to the boundary again however motions do look more
progressive in the 30 to 40 mph range which may limit rainfall.
Still extreme rainfall rates may occur.
High pressure moves in for Saturday and Sunday and lead to an
outstanding weekend. The next chance for thunderstorms arrives
Monday night through Tuesday with another boundary moving slowly
through Iowa. An another strong short wave trough will move
through Tuesday night into Wednesday and usher cooler weather to
the region.
&&
.AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/
Issued at 1256 PM CDT Wed Sep 7 2016
Scattered showers and thunderstorms will persist through the
afternoon hours and into the early evening, mainly impacting
ALO/DSM/OTM. Pockets of MVFR to IFR ceilings and even some brief
visibility restrictions can be expected within the heavier rain
through the afternoon at ALO/DSM and possibly OTM. Fog looks to
develop towards Thursday morning and kept MVFR visibility
mentioned.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 10 PM CDT this evening for Black Hawk-
Boone-Bremer-Butler-Cerro Gordo-Franklin-Grundy-Hamilton-Hardin-
Jasper-Marshall-Polk-Poweshiek-Story-Tama-Worth-Wright.
&&
$$
SHORT TERM...Podrazik
LONG TERM...Donavon
AVIATION...Podrazik
Area Forecast Discussion
National Weather Service Lincoln IL
221 PM CDT WED SEP 7 2016
.SHORT TERM...(This evening through Thursday)
ISSUED AT 220 PM CDT Wed Sep 7 2016
Main concern for this part of the forecast is with the timing of
convection. Latest radar mosaics showing thunderstorms increasing
west of the Mississippi River as they approach the eastern
Iowa/northeast Missouri borders, largely tracking east-northeast.
The storms are moving into an area with CAPE`s around 3000 J/kg and
precipitable waters around 1.9 inches, and should produce some
locally heavy rain as they clip the northwest part of the CWA this
afternoon. Additional storms are starting to increase along the
southern border of Iowa as well, and the HRRR draws the overall line
into a more west-east configuration this evening, gradually settling
southward toward the I-72 corridor. Risk of severe weather is
borderline with bulk shear on the low side (increasing to around 30
knots), but can`t rule out a couple strong wind gusts this afternoon
and evening.
By Thursday, main focus for storms will be along and south of I-72,
as the frontal boundary that has taken up residence to our northwest
finally gets booted our way with the incoming upper wave. Some
variability on how fast the front passes, but most models agree on
drier weather over the northern CWA by mid to late morning.
Precipitable water values increase to around 2.25 inches over the
southern CWA so locally heavy rains still possible with the stronger
storms.
&&
.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 220 PM CDT Wed Sep 7 2016
Stagnant pattern begins to break down as we move into the weekend.
Frontal system moving through area Thursday Night will rebound
northward Friday as the main 500 mb trough approaches Illinois.
Although not as high as Thursday as tropical moisture from Newton
moves across the Midwest, precip water values around 2 inches still
expected in the vicinity of the boundary likely producing locally
heavy rainfall. ESRL`s Atmospheric River website indicates strong
consistent integrated vapor transport through Friday. However, best
low-level forcing with the front is parallel with the moisture flow,
so it is unclear how widespread heavy rainfall will be. Will likely
be more coincident with mesoscale convective boundaries than a
widespread event. Still, local amounts of 2-4 inches may be possible
between now and Saturday morning. Although lapse rates will be
poor, moisture loading could lead to some strong winds with more
intense storms.
Models in reasonable agreement clearing the precip from the area
Saturday morning as the main trough energy pushes through the state.
Cold advection enables temps at 850 mb to drop 6-10C during the day
Saturday bringing highs below normal through the weekend.
Energy digs into the western U.S. again early next week leading to a
similar pattern redeveloping with moist southwest flow along a slow
moving frontal boundary moving southeast across the Midwest. A
little more push with this system as the low over the west cuts off
allowing for a more progressive northern stream than is in place
currently. GFS (12z)a bit faster than 00z ECMWF in moving precip
into the forecast area with GFS bringing rainfall to the area again
Tuesday. ECMWF holds off widespread rain until Tuesday Night and
Wednesday. Pretty high solution diversity evident in latest GEFS
runs so will go with a compromise solution on timing.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1220 PM CDT Wed Sep 7 2016
Convection chances will ramp up this evening as a frontal boundary
starts to sag southeastward. May see a few storms around KPIA
before 00Z, but main threat over the central Illinois TAF sites
will begin in the 00-06Z time frame and then persist periodically
through the night. By about 15Z, most of the storms should be
south of KSPI-KDEC. Some brief MVFR conditions possible within
the heavier showers, with a risk of more widespread ceilings below
3,000 feet toward the 12-15Z time frame.
Have introduced a period of LLWS from 06-12Z from KSPI-KCMI, as
several models are showing a low level jet around 40 knots to help
feed the storm intensity.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Geelhart
LONG TERM...Barker
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
415 PM CDT WED SEP 7 2016
.SHORT TERM...(This evening through Thursday)
Issued at 413 PM CDT Wed Sep 7 2016
Strong shortwave near Bismark this afternoon and its associated PV
boot rotating around the south end of it are the main concern during
the short term. These features are also within the left exit region
of a 120kt jet streak nosing into SW MN, so the forcing is strong to
say the least. Short term CAMs have actually had a decent handle on
this activity today, so followed the HRRR/HopWRF fairly closely for
timing storms in, which look to arrive in our western CWA shortly
after 6 pm. Cloud cover has limited heating, but dewpoints in the
mid/upper 60s and some partial clearing in SW MN has allowed around
1000 j/kg of MLCAPE to develop. Deep layer shear is more than ample
with 50 kts of 0-6km shear to support organized severe convection.
CAMs have been pretty persistent with a linear storm mode for us,
which means the primary threat will be strong winds. Flash flooding
isn`t too much of a concern either as storm motion will be 40+ mph.
Main question still with this potential squall line is its southern
extent. The HRRR basically has it all the way down to I-90, but WSW
to ENE orientation of 850-500 thickness lines along with upper and
llj forcing heading toward northern MN, believe storms will end up
about as far south as the Twin Cities metro. As this line heads for
western WI, it will be in quite the diminishing phase as it gets
farther and farther from the main forcing that will be heading for
the arrowhead. As for the greatest severe risk, the extent of the
marginal risk in the most recent day 1 convective outlook from the
SPC covers where the wind threat will be through tonight.
For Thursday, we get a much needed break from the wet weather and
will see the sun as well as high pressure currently over the
northern Rockies goes from SD toward Chicago. Really only area of
uncertainty with the forecast for tomorrow is with the dewpoints as
boundary layer dewpoints from the GFS and NAM continue to indicate
the potential for mixing dewpoints down into at least the lower 40s
in western MN.
.LONG TERM...(Thursday night through Wednesday)
Issued at 413 PM CDT Wed Sep 7 2016
By Thursday night, the upper level pattern will consist of a broad
longwave trough from the Pacific Northwest through the Great Lakes
region, with shortwave energy embedded in the flow. A weak surface
low will advance east through the Dakotas Thursday night through
Friday morning. It certainly appears that the main source of
forcing with the surface low and the vorticity advection in
association with the upper trough will advance east across northern
MN. There is still potential for precipitation in central MN but is
trending downward. Farther to the south, warm air advection and low
level moisture convergence is still forecast during this same time
period across parts of the Midwest, and still expect precipitation
to be possible into far southern MN in association with this
activity. Overall, this setup is trending for central MN and
western WI to end up split between two areas of focused
precipitation, although light showers could still move through the
area. The likelihood of significant QPF is diminishing.
The cold front associated with the aforementioned surface low will
pass through the area on Friday with high pressure filling in behind
it form the west and the upper trough becoming compact and centered
over our area by Saturday morning. Cooler temperatures will
spread across the upper midwest under said trough.
As the ridge of high pressure moves off to our east Sunday,
southwesterly winds develop and we`ll see a slight warm up Sunday
and Monday. A stronger cold front looks to move through on Monday
and cool air quickly fills in behind it as highs Tuesday should top
out in the mid 60s. Lows next Tuesday night could drop into the
lower 40s in parts of the CWA.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 128 PM CDT Wed Sep 7 2016
A warm front is beginning to take shape this afternoon just south of
MSP/RWF. As this boundary lifts into central MN/NW WI, there is
support from the RAP and NAM in showing what LAMP guidance has with
VFR CIGS moving into all but AXN/STC this afternoon. Attention
tonight turns to convection coming across ND right now. The hrrr has
had a pretty good handle on this activity, so followed it for
timing a squall that looks to enter western MN around 00z.
Confidence is highest that AXN and STC will be impacted by the
line. RWF/MSP will be near its southern extent while it should be
dissipating as it enters western WI.
KMSP...The HRRR has been pretty adamant on TSRA impacting MSP
around 4z with 13z through 17z runs. Only reason we kept it VCTS
is MSP looks to be on the south end of the line and it`s certainly
possible that the storms go north of the field. There is a weak
surface low right now near the MN/IA/WI border, which has allowed
winds to back around to the NW, followed the HRRR for wind
direction forecast this afternoon as it has picked up on the
development of north winds in the metro. Post storms, followed
more of a RAP idea which says we have a good punch of dry air
coming in behind the storms, with low cigs likely not hanging
around long like the LAMP has.
/OUTLOOK FOR KMSP/
Fri...Chc MVFR in SHRA/TSRA. Winds SE 5-10 kts BCMG SW.
Sat...VFR. Wind NW 10-15 kts.
Sun...VFR. Wind S at 10kt.
&&
.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&
$$
SHORT TERM...MPG
LONG TERM...SPD
AVIATION...MPG
Area Forecast Discussion
National Weather Service Raleigh NC
235 PM EDT WED SEP 7 2016
.SYNOPSIS...
A strong high pressure ridge will extend over the region through
Saturday. A cold front will cross the area on Sunday.
&&
.NEAR TERM /through tonight/...
As of 220 PM Wednesday...
The rather spacious batch of showers and thunderstorms which has
impacted our far NE over the last few hours is shifting slowly SE
out of the CWA. But a few showers have formed on the periphery of
this cloud and CINH shield, in a NNW to SSE oriented band just N and
E of Raleigh, in an area with steep low level lapse rates (8-8.5
C/km) and decent effective shear of 25 kts, under the influence of
weak DPVA from a subtle wave rotating around the SW side of the low
off the Northeast states. The HRRR and high-res WRF-ARW picked up
somewhat on this, although neither captured the areal extent very
well. I expect this activity to persist for another few hours but
wane quickly as dusk approaches, so will expand the small chance
pops to cover a bit more of the NE CWA (basically from Raleigh to
the north and east) through early evening. The mid-upper level speed
max partially responsible for the shower/storm cluster will hold in
place through tonight, with models indicating that upper divergence
will persist and may even strengthen a bit tonight, although the
eastward drift of the low off the Northeast states will lead to a
dwindling potential for weak DPVA overnight. That said, the HRRR and
WRF-ARW do brush convection near our NE sections overnight. Will
leave in an isolated mention of a shower in the far NE through the
night. Elsewhere, the growing influence of the mid-high level ridge
building in from the SW will lead to even smaller mid level lapse
rates and drying aloft, so it should remain dry over the rest of the
CWA tonight with only scattered mid clouds at most as debris clouds
roll off the higher terrain. Lows 67-72. -GIH
&&
.SHORT TERM /Thursday and Thursday night/...
As of 235 PM Wednesday...
Mid-high level ridging will continue to build in from the SW.
yielding rising heights and drying through the column as the low off
the Northeast heads further out to sea. The dry and subsidence
column will make for a dry forecast, although scattered convective
clouds may become broken at times. Low level thicknesses are
projected to be about 5-7 m higher than today, suggesting high temps
mostly in the mid 90s, except for some low 90s in the far SE (sea
breeze) and far NW. Expect fair skies Thu night with lows around 70
to the lower 70s. -GIH
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 220 PM Wednesday...
A lingering frontal boundary across Virginia will stay north of the
area of Friday and Saturday, keeping central NC in a warm, but
fairly dry airmass to start the weekend. With high pressure and an
upper ridge over the area, high temperatures will climb into the mid
90s but dewpoints remaining in the 60s should keep heat indices
below 100 degrees.
The ridge begins to break down and the pattern starts to change on
Sunday as A low pressure system moves across Ontario and Quebec and
drags a cold front across the Appalachians and into the Carolinas.
Timing of this front has slowed down a bit and so we are not
expecting precipitation until late Sunday afternoon and into the
evening and temperature effects wont be realized until Monday. For
Sunday expect highs near 90 degrees and precip chances increasing
into the afternoon but due to the lack of moisture with the front,
showers and storms could be widely scattered so not expecting a
washout at all.
Models disagree on where the front will reside early next week with
the ECMWF solution keeping it along our southern tier whereas the GFS
pushes it completely through the area. That leaves a low confidence
forecast for afternoon showers and thunderstorms on Monday, Tuesday
and Wednesday so will keep slight chances in the forecast for now.
Temperatures should be cooler, in the low to mid 80s Monday
afternoon before creeping back into the upper 80s by midweek.
&&
.AVIATION /18Z Wednesday through Monday/...
As of 120 PM Wednesday...
VFR conditions will dominate all central NC terminals through early
Thu afternoon, as we remain largely under the influence of deep dry
high pressure aloft over the region. Clouds will be mostly scattered
in nature, with bases above 4K ft AGL, although RWI will be the
exception as broken VFR clouds are likely this afternoon into early
evening, the result of disturbances rotating around low pressure off
the Northeast coast, swinging southeastward through northeast NC.
Surface winds will remain mostly light, under 8 kts.
Looking beyond 18z Thu, patchy light fog is possible each morning
mainly at RWI, but the chance of this and any potential impacts will
be low. Otherwise, VFR conditions are likely to hold through Monday,
although passage of a cold front on Sunday will bring a chance of
sub-VFR conditions within and near scattered showers and storms,
mainly in the afternoon into early evening. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...Hartfield
LONG TERM...ELLIS
AVIATION...Hartfield
Area Forecast Discussion
National Weather Service Blacksburg VA
332 PM EDT Wed Sep 7 2016
.SYNOPSIS...
A weak disturbance will drop south across the region this afternoon
into tonight, before stronger high pressure builds back into the
area from the southwest for the end of the week. A cold front will
move into and through the region Saturday night into Sunday.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 330 PM EDT Wednesday...
Northwest flow aloft will continue with our area between the remnant
Hermine low pressure south of Long Island in the Atlantic ocean and
high pressure and upper ridging to the southwest. A weak shortwave
will drop south this afternoon into this evening across eastern
portions of the forecast area. The NAM, Hiresw-arw-east, RNK WRFarw,
and HRRR support the mention of isolated convection mainly in the
northeast and east this afternoon into tonight. SWODY1 has placed a
marginal threat for severe thunderstorms to our northeast from PA
to northeast Virginia. The best instability and richer capes remain
to our north and east. With storm movement to southeast, an isolated
strong thunderstorm with heavy downpours and gusty may be possible
in the far northeast portion of our forecast area.
Any convection should slide east of the area this evening with
ridging aloft strengthening from the southwest in wake of the
passing impulse this evening into tonight. This should result in
mostly clear skies with patchy fog overnight into Thursday morning.
Low temperatures will range from around 60 in the mountains to near
70 degrees in the Piedmont.
The upper level ridge, centered over the Tennessee Valley and
southern Appalachains mountains will slowly shift east on Thursday.
An isolated storm may be possible Thursday afternoon along the
Southern Blue Ridge with low level convergence and heating. The GFS
is the only model hinting for isolated convection across the
southern high terrain. For now, kept the Thursday afternoon forecast
dry. High temperatures on Thursday afternoon will vary from the
lower 80s in the mountains to the mid 90s in the Piedmont.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 325 PM EDT Wednesday...
Will keep probability of precipitation confined north of Rte 460 on
Friday. With more cloud cover in the north will also keep maximum
temperatures a couple of degrees cooler.
Models bring surface and low level winds around to the southwest
ahead of the front on Saturday. So CAPE values end up in the 1000-
200 J/KG range just ahead of the front late Saturday due to the
increase in moisture and expectation of good heating during the day.
Just bringing a slight chance of thunderstorms into the far western
county warning area, mainly based on the location of the front
by 00Z/8PM.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 331 PM EDT Wednesday...
Good consensus in the operational and ensemble long range guidance
with the timing and strength of a long wave trof and surface cold
front crossing through the eastern United States on Saturday night
and Sunday.
More questionable if front pushes far enough south of the forecast
area for deeper moisture to clear out of the southern county warning
area. Once high pressure behind the front moves offshore and low
level winds come around to the southeast and the potential for
widespread clouds and possible stratiform precipitation returns to
the eastern upslope areas along the southern Blue Ridge on Monday
and Tuesday.
12Z guidance has also come in cooler with the air mass behind the
front on Sunday and Monday so will be trimming back minimum
temperatures for Sunday night and Monday night.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
As of 127 PM EDT Wednesday...
VFR conditions will prevail for most of the region, outside of MVFR
diurnal convection and patchy overnight valley fog.
A weak disturbance on the west side of the remnants of Hermine will
head south into eastern sections of the region this afternoon into
tonight.
Isolated MVFR showers and thunderstorms are possible this afternoon
into tonight, mainly northern/eastern sections. However, not
expecting enough coverage at any of the terminals to warrant mention
in the forecast, with KLYH possibly the closest. Therefore mainly
looking at VFR scattered/broken cumulus and broken mid deck at times
this afternoon into tonight.
With Northwest flow aloft, appears any convection will track to the
southeast and end across the east early this evening followed by
mainly clear skies and light winds. The combination of low level
moisture and light winds will result in pockets of fog overnight
given clearing and increasing moisture with potential for all
locations excluding KBLF/KROA to see a period of sub-VFR toward
daybreak Thursday. Appears KLWB could drop to LIFR late with KBCB
IFR to MVFR as well.
Morning low clouds and fog will lift or burn off quickly Thursday
morning, leaving vfr conditions. An isolated shower or thunderstorm
is possible Thursday afternoon, however most taf site will be dry.
Winds will be west around 10 mph or less.
High confidence on ceilings, visibilities and winds during the taf
period.
Extended aviation discussion...
The vast majority of the period through Sunday will be VFR.
Moisture will increase through late in the week in advance of a weak
cold front that should remain to the north Thursday afternoon into
Friday. This boundary may prompt some isolated to scattered showers
and storms, primarily during the heating of the day on Friday. A few
of the stronger ones of these could produce some temporary sub-VFR
conditions. Late night and early morning river and valley fog will
also be possible.
A more substantial front is slated to move into the area Saturday
night into Sunday. Some localized sub-VFR ceiling may accompany
this feature along with better organization of showers. Models
however do not offer a lot of hope that the activity will survive
the trip east of the Blue Ridge at this point.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH/KK
NEAR TERM...KK
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...JH/KK
Area Forecast Discussion
National Weather Service Tucson AZ
212 PM MST WED SEP 7 2016
.SYNOPSIS...Post Tropical Cyclone Newton will continue to quickly
move through the area this afternoon and evening. In its wake,
conditions will gradually dry out although isolated showers and
storms will be possible on Thursday. Dry weather is forecast Friday
and Saturday although storm chances will gradually increase Sunday
into next week.
&&
.DISCUSSION...
Post Tropical Cyclone Newton continues to rapidly decay this
afternoon as it makes its way through Pima County. Per conversation
with NHC, the system did not enter Arizona as a Tropical
Storm, leaving the total number of Tropical Storms entering AZ at 5.
Widespread light to moderate rainfall was observed with this storm
with the most impressive rainfall totals (3-4 inches) near the
international border. Amounts in the lower elevations (including
Tucson) were generally around 0.75-1.00 inches with much higher
amounts in the surrounding mountains. Radar imagery as of 20Z
indicates the heaviest rainfall is located across portions of
eastern Pinal and Graham Counties with showers diminishing quickly
around Tucson, Nogales, and Douglas. Meanwhile, visible satellite
imagery suggests a small amount of clearing just south of Lukeville,
AZ although thus far cloud tops haven`t cooled substantially in this
area of increased insolation.
The stratiform rainfall north and east of Tucson will continue to
move out of the region through late afternoon. Focus then shifts
to see if convection can develop in the area of clearing over
northern Mexico. Convective allowing models from the UofA suggest
development along the international border into Santa Cruz and
Cochise Co whereas the past few runs of the HRRR are a bit more
conservative. Observational trends suggest storms will struggle
south of the border and it seems far fetched that widespread flash
flooding will occur through the remainder of the day. Therefore I`m
going to discontinue our Flash Flood Watch a few hours early.
As for the wind potential, it`s been a mixed bag of relatively light
winds as well as impressive gusts. For a while locations along the
border were light/vrb, then gusting close to 70 mph in the
mountains, then calm again. For the most part the Wind Advisory has
worked out ok and there are still some locations experiencing gusty
winds. I`ll let the Advisory run til 00Z east and south of Tucson
but will cancel it elsewhere. Winds should diminish area-wide around
00Z.
Following any potential convection this evening, clouds should thin
out a bit overnight but dewpoints will be slow to drop. While not
common for this time of year, there could be some locations that see
fog development especially along the border early Thursday morning.
Tough to say how widespread it would be since skies won`t be
completely clear but I felt it was worth including in the forecast in
some locations.
The forecast from Thursday onward has been relatively unchanged as
the inherited forecast closely matched today`s 12Z operational and
ensemble guidance. A downward trend in storms is forecast Thursday
through Saturday with moisture returning Sunday into next week.
Friday into Saturday a 590+ 500 mb high over the area will allow
afternoon temps to climb further to above normal levels again and
should suppress convection across the area thus I went for a mostly
dry forecast for those two days and tweaked temps up a couple of
degrees. May see another 100 in Tucson before we put that to bed.
By Sunday, an upper level trough is begining to develop along the
west coast while the high slips to the east which will allow for a
return flow of some moisture and scattered convection Sunday onward.
This will also allow afternoon temperatures to gradually trend down
once again back to seasonal norms.
&&
.AVIATION...Valid thru 08/23Z.
Improving conditions are expected this evening as Newton
moves northeast away from the region. Scattered to numerous
-SHRA will diminish this evening, although fog may develop late
tonight and during the overnight hours at the KTUS, KOLS and KDUG
terminals.
Expect cloud decks at 3-6k ft agl thru 08/02z, rising to 5-8k ft agl
by 08/06z, with local MVFR CIGS/VSBY. Stronger sfc winds are
expected at the KDUG and KFHU terminals thru 08/03z, with sustained
winds of 13-23 kts. Otherwise, surface winds generally less than 12
kts. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Scattered to numerous showers will be on a
downward trend this evening as the remnants of Newton continue
to move northeast away from the region. Lingering moisture
will result in a slight chance of showers and thunderstorms Thursday
through Monday, especially over the higher terrain, with 20-ft winds
returning to their normal diurnal trends.
&&
.CLIMATE...The lowest maximum daytime temperature on record for
Tucson International Airport today, September 7, is 77 degrees set
in 1919. At midnight it was 77 degrees and dropping and provided we
don`t rise above 77 the remainder of the day we will have tied the
old 97 year old record. The maximum recorded rainfall for Tucson
International Airport on Wednesday, September 7, is 1.15 inches set
in 2006.
&&
.TWC Watches/Warnings/Advisories...
Wind Advisory until 5 PM MST this afternoon for AZZ507-AZZ508-AZZ512-
AZZ513
&&
$$
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