Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/05/17
Area Forecast Discussion
National Weather Service Albany NY
1054 PM EDT Fri Aug 4 2017
.SYNOPSIS...
Warm and humid conditions will remain in place through
tonight. This will keep the threat for additional showers and
thunderstorms in the forecast. Showers and thunderstorms increase
tonight into early Saturday along and ahead of a cold front. A
cooler and drier air mass is expected for the remainder of the
weekend before more wet weather arrives for early next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
Pre-frontal trough and associated convection now working into
western CWA. Surface instability is near nil along with high
CIN. Some elevated instability still available, but general
trend of line as it has worked east has been for a slow
weakening. No warnings have been issued on this line and I don`t
anticipate any through the night.
This update tracks with HRRR and radar. With HRRR running 1-2
hours too slow, forecast reflects a HRRR sped up by about 2
hours.
HRRR shows some strengthening in convective activity during
Saturday morning. At 12Z, model consensus supports a frontal
position roughly along or just west of the Hudson Valley. Main
question will be if any destabilization can occur to the east of
the front to support an additional convective threat. Given the
likely presence of prefrontal clouds and precipitation and
early frontal passage, this potential is questionable. However,
NAM still generates MLCAPE of 1000-1500 J/kg east of the Hudson
by 18Z, with deep- layer shear around 40 kt. SPC marginal risk
from the Hudson eastward appears to handle this situation
properly. Best potential for thunderstorms and severe weather is
over our western New England counties. Otherwise, a drying and
clearing trend will occur behind the front from west to east.
Dewpoints drop into the mid- 50s to lower 60s by the afternoon
hours, with a moderate westerly breeze. H850 temps drop to
around +7C over Lake Ontario, whose average surface temp is
around 22C, so could be looking at some lake-effect clouds and
showers over the western Adirondacks by late in the day.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Quiet weather Saturday night into Sunday as upper flow becomes
zonal upstream of the passing trough. Lows finally back into the
50s under mostly clear skies Saturday night, with some upper 40s
in the higher terrain. A bit breezy again on Sunday with highs a
few degrees below normal in the upper 60s to upper 70s.
Sunday night into Monday, a broad trough will deepen over the
Western Great Lakes, sharpening as it tracks toward the
Northeastern US. A surface low is expected to develop downstream
of the trough over the eastern seaboard. Still various solutions
on the track and strength of the low, with the ECMWF on the
stronger, northern end of the envelope (developing a seasonably
strong low within a coupled upper jet structure), and the GFS on
the weaker, southern end. Enough consensus for likely PoPs for
the northern half for Monday and categorical for the southern
half. Should the ECMWF verify, we could be looking at a
widespread, steady, moderate rainfall event. Regardless, it
looks to be cool with temperatures struggling to reach 70 in the
warmest spots. While most of the rainfall looks to occur Monday,
it could start in spots late Sunday night.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Those seeking relief from the heat are in luck as the extended
period will feature temperatures running slightly below normal for
early August (normal highs low 80s) accompanied with lower humidity
levels. Besides seasonably cool temperatures, we can also expect a
mix of pleasant days with high pressure in control along with
unsettled days that bring threats of showers and possible
thunderstorms.
Based on current guidance, the start of the extended outlook looks
wet as our rather robust low pressure system from Monday could
linger pasted sunset. While there is still uncertainty on exact
timing, given the impressive dynamics including an intensifying
shortwave in the Great Lakes and 95-105kt 300mb jet over the
Northeast, rain could continue into the evening. For now, have high
end chance POPS N/W of the Capital District and likely POPS in
southeastern zones (western MA, NW CT and lower Hudson Valley)
Monday evening as the system exits into New England. Due to the
dynamics, south/eastern areas could even see periods of steady rain
during this time with both the Euro and Canadian in agreement on
this solution.
Most of the rain should be out by daytime Tuesday but the associated
upper level trough swings into the Northeast during the day which
could lead to returning isolated to scattered showers. Guidance does
show a H850 cold pool of 7-8C moving into the northern CWA so may
even have to monitor potential hail/graupel, especially if enough
sun peaks through during the afternoon hours. Temperatures Tuesday
should be warmer than Monday but still below normal reaching only
into the low - mid 70s. In addition, northerly surface winds could
be a bit breezy Tuesday as well as a 1020-1025mb high from the Ohio
Valley nosing into the region behind out departing low.
High pressure takes control Wednesday giving us a very pleasant day
with temperatures near to slightly below normal in the mid - upper
70s. The high shifts into New England Thursday and returned
southwesterly flow sets up over the area so we should reach around
80 with dew points rising a bit as well.
Friday and Saturday turn more unsettled as our next shortwave exits
the Midwest and with southwesterly flow in place, instability could
lead to threats of showers and thunderstorms. Temperatures should
increase to around normal with dew points on the rise as well.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Looks like all terminals should be dry over the next several
hours. Nearest thunderstorm activity is across the Adirondacks
west of KGFL and moving north. Hi resolution models point toward
a lull in the activity.
A cold front working across western NY will approach the
terminals toward sunrise Saturday. Models suggest limited
instability in place with morning FROPA. For now, while
acknowledging chances of TSRA with front, chances are too low to
include in the TAFs.
There will be a light breeze this evening. That should keep IFR
BR/FG at bay for most locations. I did include a period of IFR
BR at KPSF tonight given some clearing.
Outlook...
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: High Operational Impact. Likely SHRA.
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Low Operational Impact. Slight Chance of SHRA.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
A cold front will pass through the region tonight into early
Saturday, bringing widespread showers and thunderstorms to the
area. Rainfall is expected to linger into Saturday from the
Hudson Vally eastward, with a drying trend from west to east
during the day. A cooler and drier airmass will continue to
filter in on Sunday, with RH values falling into the mid-40s to
mid-50s. Westerly winds may gust to 20-25 mph behind the front
Saturday and during Sunday afternoon. Another widespread
rainfall event is expected for Monday.
&&
.HYDROLOGY...
Widespread showers and thunderstorms, some containing heavy
rainfall, are expected tonight into Saturday morning as a cold
front moves east across the region. Localized ponding of water
in low lying/poor drainage and urban areas will be possible, but
progressive nature of the system will limit the flooding
threat. Additional showers and thunderstorms are likely for
areas east of the Hudson Valley Saturday morning into early
afternoon.
Dry weather will build in for later Saturday afternoon and
Sunday.
Another widespread rainfall event is expected late Sunday night
into Monday.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...BGM/Thompson
NEAR TERM...OKeefe/Thompson
SHORT TERM...Thompson
LONG TERM...Speciale
AVIATION...OKeefe
FIRE WEATHER...BGM/Thompson
HYDROLOGY...BGM/Thompson
Area Forecast Discussion
National Weather Service Binghamton NY
927 PM EDT Fri Aug 4 2017
.SYNOPSIS...
A strong area of low pressure will push a cold front through the
area late tonight. This front will trigger another round of showers
and isolated thunderstorms overnight. High pressure will bring
cooler and drier air for the weekend. The next chance for more
rain will come on Monday as low pressure tracks into the mid-
Atlantic states.
&&
.NEAR TERM /THROUGH SATURDAY/...
900 pm update....a weakening area of convection was continuing
to slowly work east into central NY and northeast PA close to
the I-81 corridor. This activity was generated from higher CAPEs
earlier this evening along with increased shear and upper
forcing. Since CAPEs were falling this activity will wane by
late evening. The upper level wave and associated surface front
will swing by overnight and lead to more showers and isolated
thunderstorms later tonight. Not expecting any additional severe
weather. Also the rain rates from the current convection and
the activity moving into western NY and western PA are low
enough to preclude the threat for flash flooding. SVR watch #439
has been allowed to expire. The HRRR has the best handle on the
on-going activity and used this as guidance for our hourly POPs.
Previous discussion is below...
Scattered thunderstorms were popping up across much of central
NY and northeast PA especially east of I-81. This was in the
area of highest instability where mixed layer CAPEs were
1500-2000 J/KG. However, the shear was not that impressive and
as a result we are seeing pulse storms some of which are
approaching severe limits. So we have issued a few special
weather statements. We expect this activity to continue into the
late afternoon and then wane some as the forcing and shear were
weak. Main forcing associated with a vigorous upper level wave
and attendant cold front was west of our forecast area at this
time. As this feature works east- northeast into the evening,
forcing and shear will increase and the more organized
convection will work east reaching Steuben/Yates counties around
21-22z and to the I-81 corridor by 00z-01z. Instability won`t
be as high by this time but still should be around 1000 J/Kg.
0-1 km shear will approach 30 knots with similar shear values
above so we expect a line of storms to pass through with the
potential for damaging winds, hail and locally heavy rain.
After this line of storms fizzles late this evening due to loss
of heating the front will cross the region overnight and likely
will be accompanied by more showers and isolated thunderstorms.
Not expecting additional severe late tonight. At this point it
doesn`t look like heavy rain potential lasts after midnight.
Best chances for heavy rain and localized flooding will be
during the afternoon and evening today with the scattered
activity this afternoon and more organized activity this evening
given the very wet antecedent conditions.
After the front crosses the region Saturday morning, there will
be widespread broken stratocumulus, especially in central NY
and far northern PA with lingering scattered showers. Showers
will linger in our northern counties into the afternoon as
well. We do expect some clearing in northeast PA and south
central NY later Saturday.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Saturday night...Upper level trough axis moves east of the
region while surface ridging also occurs from high pressure in
the mid Atlantic. Will continue to carry chance/slight chance
pops in the far north during the evening hours then the rest of
the overnight period will be dry. Overnight lows will range in
the lower to middle 50s.
Sunday...Zonal flow aloft with no apparent short waves along
with high pressure near the mid Atlantic coast will provide a
dry day with partly sunny skies. Highs will generally be in the
middle 70s.
Sunday night/Monday...A fairly strong mid level short wave will
track from the Ohio valley across Pennsylvania and through
central New York during the period. The resulting surface low
tracks from the Tennessee/Ohio Valleys east through the mid
Atlantic region and into coastal New England. Showers will
spread across northern Pennsylvania and into the southern tier
late Sunday night with widespread rain across the entire region
on Monday. Another system with plenty of moisture to work with
could produce rainfall totals between 1.0-1.5 inches over
northeast Pennsylvania and the southern Catskills.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The above mentioned system moves off the New England coast
Monday night keeping the chance for showers over the area.
Tuesday through Wednesday night looks mainly dry due to weak
ridging aloft and high pressure in the vicinity. Next chance for
showers and thunderstorms will be Thursday through Friday as
another broad upper level trough re-establishes itself in the
Great Lakes region along with an approaching frontal boundary.
Temperatures through the period will be near seasonal normals.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Line of thunderstorms will move across all terminals between 00z
and 04z. Flight conditions will drop to IFR in heavy rain with
thunder and mist. We also have wind gusts to between 35 and 40
knots as the line moves through. We time the line through ELM
around 00z, ITH around 0030z, SYR at 0100z, RME at 0200z, BGM
around 0130z and AVP around 2-3z. Once this line of
thunderstorms moves through we expect mainly VFR in showers and
some thunderstorms until the cold front passes between 2 am and
5 am. After the front passes by, we will see an MVFR ceiling
with lingering showers all Terminal sites which will improve to
scattered to broken VFR between 15z and 20z.
Winds will be southerly 10-15 knots gusts to 25 knots until late
evening then southerly 5 to 10 knots overnight. Winds will
increase from the west winds to 10-15 knots with gusts to 20-25
knots by Saturday afternoon.
Outlook...
Saturday night...Generally VFR. Chance for IFR valley fog late.
Sunday...VFR. Chance early morning IFR valley fog.
Monday and Tuesday...Restrictions possible in showers and
thunderstorms.
Wednesday...VFR...chance of early morning IFR valley fog
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN
SHORT TERM...RRM
LONG TERM...RRM
AVIATION...DJN
Area Forecast Discussion...Updated
National Weather Service Billings MT
855 PM MDT Fri Aug 4 2017
.UPDATE...
Difficult forecast this evening trying to determine extent
and timing of thundershowers. Fortunately, we are not expecting
any significant impacts, though we do have a few community events
going on this evening that may be affected.
Main push of cooler air and north winds now approaching Billings
from the N/NW and can easily be identified on KBLX radar. North
winds 15 to 25 mph behind this boundary based on upstream ground
truth. We expect it into the Billings vicinity between about
915-1000 PM. We finally have some showers developing as well at
this time off the Snowies as the ascent from upper trough moves
toward us. We also have some showers moving into Park/Sweet Grass
Counties at this time. High resolution models want to keep the
stuff to the north tracking across Musselshell eastward overnight,
but do bring the showers to the west across central Yellowstone
County and southward to the Pryors by late evening. This seems to
be the scenario shaping up so we will tweak PoP`s as necessary. BT
&&
.SHORT TERM...valid for Sat and Sun...
Water vapor imagery shows a strong-for-early-August clipper in
southern Alberta dropping toward MT and the western Dakotas. This
is the main feature of interest through the weekend.
Today is a pre-frontal day and we have warmed up to the 80s with
90F already in some locations. Convection has yet to develop,
likely due to a weak mid level cap, but it will be on the increase
into this evening as ascent increases. Canadian front has reached
Lewistown and gusty north winds have recently developed through
Judith Gap. Well-mixed north winds will spread across our western
lower elevations over the next few hours. Latest HRRR runs hold
off on any convection until after 03z, in line with PV advection
from the northwest, but there is another area of weaker PV in ID
which, along with the surface front, could provide enough ascent
to allow isolated thunderstorms to develop by late afternoon or
early evening. Will sustain low pops thru 03z, then introduce
higher (scattered) coverage by 03z. Combination of frontal winds
and convection will bring a risk of gusty north winds across our
western and central cwa throughout the evening hours. In fact,
even without storms it will become breezy, with the latest RAP
showing 850mb winds to near 35kts nosing into Musselshell and
Yellowstone Counties by late evening. Something anyone with
outdoor plans will need to watch, as well as those with fire
concerns.
Cooler and unsettled weather with a daily chance of showers and
thunderstorms is on tap for the weekend under persistent cyclonic
flow associated with the upper trof. As Canadian surface high
settles in, high temps will be in the 70s to near 80F (near 10
degrees below normal) both Saturday and Sunday. Will need to
monitor location of surface front as it tracks east with the
convection tonight. If it lingers over our east through Saturday,
axis of greater instability could result in some strong to perhaps
locally severe storms in the afternoon and evening. Greatest
potential of this seems to be east of Miles City and Broadus, but
it is also possible that the shift to NW winds will shove the
higher theta-e air to the Dakotas by Saturday afternoon. SPC does
have a marginal risk of severe storms in our east for day 2, and
this is reasonable at this time, but there is uncertainty and will
let later shifts evaluate the evolution of the surface front
tonight.
Upper trof will finally exit to our east Sunday night allowing for
modest height rises and drying conditions ahead of next upstream
shortwave in NW flow aloft.
JKL
.LONG TERM...valid for Mon...Tue...Wed...Thu...Fri...
Very little changes made to the extended forecast with this
issuance. Models are in good agreement Monday through Wednesday in
keeping high pressure ridging over the Pacific northwest which
will result in a northwest flow aloft across our forecast area.
This will result in continued below normal temperatures Monday and
Tuesday with readings in the upper 70s to lower 80s. A few weak
disturbances within this northwest flow will bring a slight
chance for a shower or thunderstorm almost daily. However, this
will be just a slight chance as models are not showing any strong
system at this time. High pressure ridging begins to build
Thursday into Friday bringing warmer temperatures, around normal
for this time of year, with readings in the upper 80s. Hooley
&&
.AVIATION...
Showers and thunderstorms will develop west of
Billings and move east across the region late this evening and
overnight. MVFR conditions along with wind gusts around 30 to 40
kts are possible with these thunderstorms. Otherwise, VFR
conditions will prevail through the overnight hours. AAG
&&
.PRELIMINARY POINT TEMP/POPS...
Sat Sun Mon Tue Wed Thu Fri
-----------------------------------------------------------
BIL 060/077 054/076 051/081 054/082 056/083 058/085 060/088
32/T 22/T 10/U 02/T 11/U 12/T 11/U
LVM 052/077 048/075 046/080 049/080 048/080 049/084 050/087
33/T 22/T 10/U 02/T 12/T 12/T 22/T
HDN 058/078 052/077 049/083 054/083 057/084 059/088 059/090
33/T 22/T 11/U 02/T 11/B 12/T 11/U
MLS 061/080 054/075 052/081 056/080 056/081 059/085 060/089
33/T 23/T 21/U 01/U 11/U 12/T 11/U
4BQ 059/080 053/075 051/080 055/083 056/082 059/087 060/088
23/T 23/T 21/U 01/B 12/T 12/T 11/B
BHK 055/077 050/072 047/078 052/078 051/079 056/085 056/084
34/T 44/T 21/U 00/U 01/U 11/B 22/T
SHR 057/076 052/072 048/077 052/077 053/080 054/084 055/085
24/T 23/T 21/U 02/T 22/T 22/T 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Dodge City KS
618 PM CDT Fri Aug 4 2017
...Updated Aviation Discussion...
.SHORT TERM...(This evening through Saturday)
Issued at 1240 PM CDT Fri Aug 4 2017
Thunderstorms will be possible across extreme southwest Kansas this
evening as a series of H5 vort maxima move out of the Colorado
Rockies into the Western High Plains within west-northwest flow.
Although the flow aloft will remain fairly weak, steep low/mid level
lapse rates in a band of convergence in the vicinity of a slowly
strengthening lee side trough will be enough to trigger thunderstorm
development late this afternoon across the high plains of eastern
Colorado with a few storms potentially drifting into west central
and southwest Kansas later this evening. A moderate amount of
instability and shear will be present increasing the potential for
strong to marginally severe storms with small hail and gusty winds
in excess of 40 mph the main concern. The focus for thunderstorms
shifts east into central Kansas Saturday as a developing surface
low in eastern Colorado pushes into western Kansas by Saturday
afternoon. Again, the potential for strong to marginally severe
storms will exist.
Temperatures will not be as cool tonight as a prevailing southerly
flow draws slightly warmer air northward, not to mention marginal
moisture advection. Lows generally down into the 60s(F) can be
expected tonight. Lee side troughing will strengthen Saturday
turning winds more southwesterly through the day and reinforcing
warm air advection into western Kansas, pushing high into the lower
to mid 90s(F) mid to late afternoon.
.LONG TERM...(Saturday night through Friday)
Issued at 210 PM CDT Fri Aug 4 2017
Should see a brief break to precip chances during the day Sunday in
wake of yet another frontal passage. A rather weak westerly flow
aloft and a lack of favorable shear and instability is expected to
hinder thunderstorm development through Sunday evening. However, an
easterly upslope flow and steep low/mid level lapse rates will
likely lead to thunderstorm development off the front range of the
Colorado Rockies late in that same afternoon. Cannot rule out a
stray storm or two drifting into extreme western Kansas late
Sunday night into early Monday morning. The GFS/GEM/ECMWF show
very little change to this pattern through mid week with a modest
westerly flow aloft paired with a low level east to southeasterly
upslope flow. With sufficient moisture/instability present, this
will present a reasonable chance for thunderstorms across portions
of western Kansas each day through at least Wednesday.
Temperatures will not be as warm Sunday in wake of a cold front
moving through western Kansas Saturday night. Cooler air will filter
southward into western Kansas keeping highs from climbing above the
80s(F) Saturday afternoon. Surface high pressure will linger across
the Upper Midwest through the middle part of the week, reinforcing
the cooler air mass across the high plains and keeping temperatures
well below normal during much of the period. Highs may only reach
the 70s(F) across much of western Kansas Monday before temperatures
begin to slowly rebound into the 80s(F) later in the period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 615 PM CDT Fri Aug 4 2017
A surface warm front will lift north across western Kansas early
tonight. As this warm front passes the south to southeasterly
winds at around 15 knots will shift to the southwest at Liberal
and eventually Garden City and Dodge City. At 06z Saturday this
frontal boundary is forecast to be located near Garden City and
Dodge City. The NMM, ARW, and HRRR at 12z Saturday place this
boundary approximately half way between Garden City and Hays.
Moisture and lift developing north of this boundary overnight will
may give rise to some late night convection, mainly northeast of
Garden City and Dodge City. Based on this will only mention VCTS
at Hays but leave all mention of the thunder out at Garden City
and Dodge City. Model soundings keep cloud based overnight into
Saturday, even with this scattered convection, at or above 6000ft
AGL. Between 15z and 18z Saturday the southwesterly winds will
increase into the 15 to around 20 knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 65 92 65 83 / 20 30 40 10
GCK 65 91 64 82 / 20 10 20 10
EHA 65 91 63 83 / 20 20 20 10
LBL 65 93 65 84 / 20 30 30 10
HYS 63 91 64 80 / 40 30 30 10
P28 66 92 69 85 / 40 40 60 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JJohnson
LONG TERM...JJohnson
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
641 PM CDT Fri Aug 4 2017
.AVIATION DISCUSSION...FOR 00Z TAF PERIOD...
Majority of convection has dissipated at TAF issuance. Should remain
VFR throughout the evening and most of the overnight hours. Some MVFR
development looks possible for KSAT/KSSF tomorrow morning but should
stay clear of KAUS based off model projections. Do expect -TSRA
development in the afternoon with best shot at impacts at KAUS but
not enough confidence in a direct terminal impact to include a
prevailing line for this. Thus opted for VCTS as many isolated cells
will likely begin developing shortly after 18Z. KSAT/KSSF may see
some nearby convection from the east in the late afternoon. KDRT
expected to prevail VFR throughout the period.
&&
.PREV DISCUSSION... /ISSUED 304 PM CDT Fri Aug 4 2017/
SHORT TERM (Tonight through Saturday)...
Main short-term highlight will center on the isolated/scattered
showers this afternoon and again tomorrow along with the elevated
heat indices of 100-107F across the region.
Water vapor imagery and RAP H5 output indicate northwest flow across
the region with a weak shortwave trough across central Texas this
afternoon. Despite this axis of slightly enhanced divergence due to
the shortwave trough, wind shear and speeds remain very light aloft.
As such, most of the isolated shower activity is being driven by
instability alone along with outflow boundary collisions. ML CAPE
values range from 500-1250 J/Kg this afternoon across the region and
this is keeping coverage and intensity at bay. Most of the showers
have struggled to even produce lightning so far this afternoon. With
the right collisions from storm-induced outflow boundaries due to dry
sub-cloud environments (inverted V soundings), a few thunderstorms
could occur through the early evening hours before activity
dissipates out by 9-10pm.
By Saturday, the current shortwave trough flattens out to more zonal
flow over much of the region. However, another compact but weak
disturbance over the Texas Big Bend region will help generate some
additional shower and thunderstorm activity tomorrow. This feature,
coupled with the sea-breeze and diurnal instability will foster
isolated to scattered showers once again. Overall coverage will be in
the 20-40% range for most of the area. Some enhancement of greater
coverage could occur across the Coastal Plains due to the sea-
breeze.
LONG TERM (Sunday through Friday)...
Increasing rain chances appear on the horizon for late weekend and
into the early next week where 40-60% chances are currently
forecast. Pockets of localized heavy rain could also be possible
during this time as well. Scattered showers look to occur through
much of mid to late week as well, mainly during the afternoons.
The weak disturbance mentioned over the Big Bend on Saturday will
move slowly eastward on Sunday. With day-time heating, at least
scattered showers are expected across a good portion of the region
Sunday. At the same time, a potential boundary will shift south
across central OK. With general troughing and instability, a stronger
convective complex and reinforced outflow could then reach into
central Texas. The combination of the weak convective outflow plus
the disturbance and weak instability should support the start of a
wetter period.
For Monday and Tuesday, much of central Texas will be located in a
weakness and light shear axis region as PWATS increase to above 2
inches. These factors combined should allow for semi-organized
showers and storms that could produce heavy rain at times. The
greatest likelihood of higher totals currently appears to be over the
Hill Country and northern I-35 corridor locations. However, this
could change if the pseudo-convective boundary is able to slide
farther south.
For mid- to late-week, at least scattered showers are expected
during the afternoon hours as instability occurs in the high PWAT
air. Both ECMWF and GFS models indicate tropical activity could be
possible across portions of the far southern Gulf of Mexico or the
Bay of Campeche in the Wednesday/Thursday time-frame. All guidance at
this time suggests this potential system to remain well south of the
region. However, if anything changes, we`ll keep you apprised.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 76 98 77 99 78 / 20 20 10 20 30
Austin Bergstrom Intl Airport 75 97 77 97 77 / 20 20 10 20 30
New Braunfels Muni Airport 74 97 76 96 76 / 20 20 20 20 30
Burnet Muni Airport 72 94 74 95 74 / 20 20 10 20 20
Del Rio Intl Airport 77 97 76 99 78 / 20 30 20 20 20
Georgetown Muni Airport 75 96 75 97 75 / 20 20 10 20 30
Hondo Muni Airport 74 99 75 98 75 / 20 20 20 20 20
San Marcos Muni Airport 75 96 76 96 76 / 20 20 20 20 30
La Grange - Fayette Regional 75 96 77 96 77 / 20 40 20 40 30
San Antonio Intl Airport 77 96 77 95 78 / 20 20 20 20 20
Stinson Muni Airport 76 96 77 94 78 / 20 20 20 20 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...TB3
Synoptic/Grids...09
Public Service/Data Collection...YB
Area Forecast Discussion
National Weather Service Hastings NE
656 PM CDT Fri Aug 4 2017
.SHORT TERM...(This evening through Saturday)
Issued at 231 PM CDT Fri Aug 4 2017
An upper low to our northeast will continue to track eastward,
which will put us into consistent northwesterly flow aloft as we
head into this weekend. We will be impacted by a few shortwaves
aloft. These will be subtle, though, and therefore I believe that
our precipitation chances will be much more dependent on low-
level features (frontal positions, LLJ, etc.).
This evening, thunderstorms are expected to develop across
western Nebraska and track towards the area as the low-level jet
veers into the area. Current timing from the HRRR would bring this
activity into the area between midnight and 3 am. Later overnight
into Saturday morning, the models show the best convergence at
850mb to be east of Highway 281, so I would expect activity to re-
focus in this region early Saturday morning, before gradually
waning by mid to late morning. With 500-1500 J of MUCAPE and 30-40
kts of bulk shear, an isolated strong to marginally severe storm
is possible.
Plenty of uncertainty still exists in Saturday`s forecast.
Chances for thunderstorms and temperatures have large potential
for a bust and depend heavily on where skies clear and the
atmosphere can destabilize.
Speaking of clouds, models, especially the NAM, are showing that
a large portion of our CWA will be socked in under low clouds
during from the late morning through the afternoon. Therefore,
I`ve limited us to only a slight chance of a thunderstorm. Chances
may be a bit better along and south of the KS/NE border where the
NAM shows 1000-1500 J of MLCAPE. While it doesn`t look
particularly concerning, a strong to marginally severe storm is
possible.
As far as temperatures go, the current forecast ranges from the
upper 80s in Rooks county to the upper 60s in Polk and Nance
Counties. If anything, I could see this trending lower, especially
if clouds really hang around all day.
.LONG TERM...(Saturday night through Friday)
Issued at 231 PM CDT Fri Aug 4 2017
Saturday night, models show pretty limited instability, so I went
ahead and removed the mention of thunder late Saturday night into
Sunday morning. In fact, NAM sounding show very saturated low
levels trapped under an inversion...possibly indicative of fog and
drizzle. For now, I`ve left the forecast with just "rain
showers", but it is something to keep an eye on for future shifts.
For Sunday and beyond, we remain in northwest flow with off and on
chances for rain/thunderstorms in various parts of the area as a
multitude of weak disturbances push through. At this time, it
appears that the best opportunities are on Tuesday and Thursday,
although this is subject to change given the fickle nature of this
pattern.
At this point, none of these time periods look particularly
concerning from a severe weather perspective, largely thanks to
the relatively cool weather.
Temperatures will continue to be below-normal, but highs may finally
rebound into the mid to upper 80s by the end of the week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 633 PM CDT Fri Aug 4 2017
Increasing clouds and chances for showers or thunderstorms are
expected through the period...with MVFR cigs expected to develop
by the afternoon hours tomorrow. Ahead of the lower ceilings,
expect a chance for thunderstorms to spread across the area
overnight as an upper level disturbance tracks southeast across
much of Nebraska. Behind this disturbance...expect lower stratus
to filter in across the region...with generally southeasterly
winds near 12 KTS expected through much of the day tomorrow.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Rossi
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
933 PM EDT Fri Aug 4 2017
.SYNOPSIS...
A cold front will move across the area overnight. High pressure
then builds over the area through Saturday night. A warm front
will lift through the area Sunday night followed by a cold front
Monday night. High pressure is then expected through Wednesday
before low pressure affects the area late next week.
&&
.NEAR TERM /THROUGH SATURDAY/...
At 0115Z, regional radar shows continued convective activity
primarily in the extreme NW portion of the CWA. This activity
will continue as the cold front approaches from the west for the
next few hours. Currently, the cold front is just now
approaching the extreme western WV/Garrett County MD border.
The 23Z HRRR diminishes the convection associated with the cold
front as it crosses the Appalachians, then re-establishes it as
it crosses the northern Shenandoah Valley. It is mainly limited
north of I-66/US Route 5. With quite a bit of convective
inhibition already present per SPC mesoanalysis, not expecting
hazardous weather overnight as it will likely be elevated. All
shower activity will be northeast of our CWA by 600 am.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
NWly flow behind the cold front will gust 20 to 25 mph through
Saturday sunrise through the early afternoon. 850mb temps 10 to
12C north to south across the area along with the NWly breeze
will make for max temps in the low 80s. Dewpoints in the 50s
will make for a welcome refreshing change to the past several
hot and humid days.
High pressure is overhead Sunday morning with southerly flow and
moisture returning Sunday afternoon. Max temps mid 80s Sunday.
Chances for showers and thunderstorms Sunday night as a warm
front lifts through the area. Min temps mid to upper 60s inland
and around 70F for nearshore/urban centers.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
A slow moving, moisture laden frontal system will drag through the
region early next week. PWATs near 2 inches combined with strong
convergence in the midst of low pressure tracking along the slow
moving front will likely lead to numerous showers and thunderstorms
with heavy rainfall. Upper level divergence aided by a 100+ knot jet
streak at 250 mb will help sustain and organize storms, as well. The
deep-layer shear could contribute to a severe weather threat
depending on instability.
There is some uncertainty with the low track Monday which will
determine finer scale details such as where the heaviest rain sets
up and where severe weather potential (wind/hail/tornadoes) is
maximized. The NAM takes the low to the north over PA which would
lead to an elevated severe threat but perhaps reduce the widespread
heavy/persistent rain potential. The GFS is further south across
central VA with a cooler boundary layer and less severe potential
for most of the area but a significant heavy rain threat due to
strong surface convergence. The ECMWF basically splits the
difference, with various ensemble members falling somewhere in
between.
The front should sag south with high pressure building in leading to
drying conditions during the middle of the week, but just how far
south it gets remains to be seen. Shower chances may linger,
especially for southern zones if the front gets hung up. Regardless,
it will likely return north once again raising the threat for
showers and thunderstorms by the end of next week.
With a cold front near/south of the area, temperatures should run a
little below normal most of next week.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
VFR for all terminals overnight. Winds will become NW Saturday
with gusts to 20 kt and VFR conditions expected through Sunday.
Flying restrictions possible Mon due to widespread showers/
TSRA as low pressure passes the region from the west.
&&
.MARINE...
South flow increasing from high pressure offshore and a cold
front approaching from the Ohio Valley. SEly channeling
increases again this afternoon again with 20 knot gusts expected
into the evening as a cold front approaches from the west. A
SCA is in effect for the lower Tidal Potomac River and MD
Chesapeake Bay south of Pooles Island.
Scattered gusty showers and thunderstorms expected again late
this afternoon and evening ahead of a cold front. Special marine
warnings are possible.
The cold front crosses the Bay from the west late tonight into
Saturday morning. NW winds are expected to surge across the
waters after sunrise Saturday and a SCA is in effect for all
waters Saturday morning and afternoon. Winds will taper off late
Sat afternoon.
No marine hazards expected Sunday through Monday night. Winds light
and variable Sunday and Sunday night.
SCA conditions possible and SMWs may be required Mon afternoon
and evening depending on evolution of convection/track of low
pressure along a cold front.
&&
.TIDES/COASTAL FLOODING...
South winds will increase rest of today ahead of a cold front
that crosses the Chesapeake Bay late tonight. Elevated water
levels will persist into Saturday with a Coastal Flood Advisory
for minor coastal flooding during the preferred high tide late
tonight from Straits Point to Annapolis.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 9 AM EDT Saturday for MDZ014-017-
018.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Saturday for ANZ531>534-
536>543.
Small Craft Advisory from 7 AM to 4 PM EDT Saturday for
ANZ530>543.
&&
$$
SYNOPSIS...BAJ
NEAR TERM...Lee
SHORT TERM...Lee/BAJ
LONG TERM...DFH
AVIATION...Lee/BAJ/DFH
MARINE...BAJ/DFH
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service San Francisco Bay Area
855 PM PDT Fri Aug 4 2017
.SYNOPSIS...Shower chances have mostly ended this evening as the
bulk of the monsoon moisture shifts to the north and east of our
area. Less cloud cover...and thus warmer temperatures...are in
store for the San Francisco Bay Area on Saturday. Otherwise, a
gradual cooldown is forecast through Monday. However, temperatures
will still remain quite warm inland through the forecast period.
A modest warming trend is expected during the second half of next
week.
&&
.DISCUSSION...As of 8:55 PM PDT Friday...Latest KMUX radar
reveals that a final band of high-based shower activity has mostly
cleared our forecast area to the north and east. A few sprinkles
or virga are still possible over northeast Napa County and extreme
eastern Contra Costa County this evening, but for the most part
precipitation chances have ended in our area. The NAM shows
moisture lingering over the eastern portion of our area through
Saturday morning and the latest HRRR forecasts possible light
precipitation across eastern Contra Costa and Alameda Counties
late tonight and Saturday morning. However, most model data
indicate little or no chance of additional precipitation.
The mid and upper level flow is forecast to gradually veer from
southeast to southwest tonight and Saturday morning. This will
allow a drier airmass to overspread our area by tomorrow
afternoon and clear out most remaining mid and upper level cloud
cover. The result will be warmer temperatures across much of the
SF Bay Area tomorrow, especially the North and East Bay Valleys
where widespread cloud cover today prevented temperatures from
rising out of the upper 70s and 80s. Lower 90s are likely in
these valleys once again tomorrow if sunshine is more plentiful as
expected. But the overall trend this weekend and into Monday will
be towards slightly cooler temperatures as a weak upper low
offshore gradually approaches the coast. We will also likely see
an increase of coastal low clouds and fog through the weekend as
the marine layer redevelops.
As the upper low approaches over the weekend, it may bring with it
just enough residual monsoon moisture to trigger shower activity
in the North Bay late Saturday Night and Sunday, especially if the
NAM solution verifies. However, at this time there is not yet
sufficient forecast confidence to add precipitation chances to
the North Bay over the weekend.
Temperatures by Monday are forecast to be close to seasonal
averages across most of our area. A modest warming trend is then
expected during the second half of next week as an upper ridge to
our south builds gradually northward.
&&
.AVIATION...as of 4:45 PM PDT Friday...Mid and high level clouds
continue to stream across the district. The heaviest concentration
was from the northern SFO Bay Area into the North and East Bay
where a few sprinkles have been reported. The only lightning
strikes have been well offshore near the vicinity of the upper low
so chances for lightning or thunderstorm activity over land is
very low.
The other issue is the stratus. Satellite image shows stratus
about 20 miles off the coast which could move towards the coast
when the mid and high level moisture lift northward out of the
area. Latest forecast shows stratus returning after midnight but
confidence is low as it may come in later or not at all.
Vicinity of KSFO...VFR through the airport evening rush. A few
sprinkles in the vicinity through 04Z but chances for
thunderstorms is very low. MVFR/IFR cigs possible after 10Z.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...Possibility of low clouds returning to
KMRY and KSNS after 07Z.
&&
.MARINE...as of 4:45 PM PDT Friday...Echoes of precipitation can
still be observed over the coastal waters. Expecting chances
showers and isolated thunderstorms to last into this evening as
monsoonal moisture continues to pass over the region. Relatively
light seas and winds are expected with locally higher winds
possible in heavy showers or thunderstorms.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 1 AM
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: W Pi
MARINE: AS
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