Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/01/22
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1026 PM EDT Sun Jul 31 2022
.SYNOPSIS...
A weak wave of low pressure will bring a period of
light rain or showers to the southeast Catskills, mid Hudson Valley
and northwest Connecticut overnight. Otherwise, dry and mild weather
will continue from the Capital Region north and west. Warm and
mainly dry weather will continue across the entire area Monday
afternoon into Monday night, then a weak cold front will approach
from the west, bringing a chance for a few showers and possibly a
thunderstorm late Monday night or Tuesday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATE as of 1025 PM EDT... A short-wave on the GOES-16 water
vapor imagery is moving across central-ern NY and PA. At the
sfc, a warm front is lifting slowly north from the mid Atlantic
Region with a weak wave of low pressure approaching with some
showers or a period of light stratiform rainfall mainly across
the southeast Catskills, mid Hudson Valley, NW CT and south of
I-90 in the Berkshires overnight. Weak high pressure is near the
upstate NY and some dry low to mid level air is over the
region. We have seen the high clouds spread north and mid level
clouds are over the southern most zones. We increased the PoPs
over the southeast Catskills, mid Hudson Valley and Litchfield
County CT, between midnight and 3 am based on the latest 3-km
HRRR and radar trends due to the isentropic lift ahead of the
weak wave. We continued some likely PoPs near KPOU and the I-84
corridor between 3 am and 6 am. Rainfall amounts will range
from a few hundredths to a couple tenths of an inch. The
northward extent is tricky but it appears any measurable pcpn
will stay mainly along and south of the Capital District and the
Mass Pike. Showalter values are above zero and lack of elevated
instability looks present, so we kept thunderstorms out of the
forecast.
Lows will be in the mid/upper 50s over the southern Adirondacks
and southern Greens with low to mid 60s over most of the rest
of the region with some spotty upper 60s across southern
Litchfield CTY and the mid Hudson Valley.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
The weak surface wave will move east of New Jersey Monday
morning, with light rain ending across the lower Hudson Valley
before noon. The rest of Monday will be mainly dry under a
partly to mostly cloudy sky with light southerly flow. An
isolated shower cannot be ruled out in this pattern Monday
afternoon as there will be a little instability developing, but
no real organized areas of large-scale forcing for upward motion
are foreseen. High temperatures Monday will range mostly from 80
to 85, and dew points will be creeping into the mid 60s.
The next system to watch will be a cold front moving east from
the Great Lakes Monday night. Showers and a few embedded
thunderstorms will move east across western into central NY
Monday evening, but these should be weakening as they approach
our area late Monday night. A few showers and perhaps a rumble
of thunder could survive with these showers into the Mohawk
Valley, southern Adirondacks and northern Catskills late Monday
night, but from the Hudson Valley eastward conditions should
remain dry.
During the day Tuesday the remnants of this weak cold front will
be crossing the area. There will likely be a couple of lines of
weak forcing; perhaps a north-south oriented trough in the
morning and whatever is left of the actual cold front later in
the afternoon. Once again, large-scale, organized forcing for
upward motion will be lacking and the atmosphere will only be
marginally unstable. Scattered showers and isolated
thunderstorms will occur on Tuesday, but many areas will
probably see little to no rainfall. Temperatures Tuesday will be
dependent on the amount of sunshine that we see, but with any
sunshine the atmosphere should be warm enough to support highs
ranging from lower 80s over higher terrain, to upper 80s in the
valleys.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The long-term weather forecast period will consist of warm to hot
and humid conditions, along with multiple chances for showers and
thunderstorms as this summer`s anomalously strong, broad, and
relentless mid-upper level ridge centered over the Interior U.S., in
tandem with a strengthening/retrograding Bermuda ridge, and a series
of frontal systems drive our weather pattern.
We start off the extended during the middle of the workweek where
the potential of hot and increasingly humid conditions will be the
main focus on Wednesday and to a greater extend on Thursday. On
Wednesday, strong mixing via a 1016 mb surface high over head
coupled with the area being on the leading edge of some
anomalous heat (i.e. 850 values ranging between 17C-19C), will
translate to surface temperatures climbing into the mid 80s to
lower 90s along the river valleys (upper 70s to lower 80s higher
elevations). On Thursday, the heat advances further east with
850 mb temperatures ranging between 20C-22C, which is +2 to +3
STDEVs above normal per NAEFS. Temperatures of this magnitude
aloft will translate to temperatures well into the 90s along the
river valleys (80s higher elevations). The one caveat to
temperatures not reaching these levels will be cloud coverage
and the development of showers and thunderstorms, especially out
and ahead of a leading cold front. There`s still some
uncertainty with regards to how quickly the cold front advances.
Several models with ensemble support suggest a slower
progression of the front which will keep things mostly dry at
least during the first part of Thursday. Chance for showers and
storms do increase Thursday afternoon and point forward from
northwest to southeast. Will have to continue to monitor trends
on the timing/forward progression of the cold front.
Forecast models are hinting around at the possibility that the
aforementioned front could get hung/slow over the area which would
give additional chances for showers and storms Friday and possibly
extending into Saturday. Have chance PoPs for Friday over the area
and for areas roughly from Albany and point southeast on Saturday to
reflect this possibility. High temperatures on Friday and Saturday
will be tempered to near seasonable levels thanks to cloud coverage
and shower/thunder chances.
Sunday, it looks like we may have the chance to dry out with the
passage of the cool front.
Early the following week, there`s the potential for additional
showers/storms as forecast models are advertising another storm
system approaching from the west.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Through 00z Tues...VFR conditions should prevail through the 00z TAF
cycle for all of the TAF sites with the exception of KPOU and maybe
KPSF. Rain showers associated with a weak shortwave is expected to
pass mainly to our south. Forecast models do have the very northern
reaches of the precipitation shield reaching as far north as perhaps
KPSF. Given the situation, confidence is greatest that KPOU will see
rain showers.
The challenge at this time continues to be just how far north the
precipitation really get. It will be a close call. For now, have
mentioned VCSH for just KPOU starting at around 04z with Prob30s
between 09-12z. Have opted to keep KPSF dry for now and will let the
midnight shift further evaluate/assess how far north precipitation
reaches. If confidence increases, then precipitation headlines will
be included for KPSF (with similar timeframe as KPOU).
Any rain showers will have the capabilities of reducing vsbys and
perhaps cigs down to MVFR levels. Further to the north and west
(i.e. KALB/KGFL) things should remain dry with flight categories
remaining VFR.
As far as cloud trends, expect for ceilings to lower in elevation
(high clouds to low/mid clouds) in response to the aforementioned
shortwave tonight. While ceilings over KALB/KGFL will remain VFR,
ceilings at KPOU/KPSF are expected to be in the low VFR/high MVFR
range tonight. Tonight, will be mostly cloudy over the TAF sites.
Around daybreak, coverage should be better over KALB/KGFL compared
to KPOU/KPSF. Once precipitation ends around daybreak, skies will
gradually improve over the TAF sites giving way to a mostly sunny
day on Monday.
Light winds this evening is expected to remain light (at less than 5
kts) and/or become calm tonight. Calm winds overnight are expected
to become light out of the south on Monday at around 5 kts.
Outlook...
Monday Night: Low Operational Impact. NO SIG WX.
Tuesday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Moderate Operational Impact. Chance of SHRA...TSRA.
Thursday Night: Moderate Operational Impact. Scattered SHRA...TSRA.
Friday: Moderate Operational Impact. Scattered SHRA...TSRA.
&&
.FIRE WEATHER...
A wave of low pressure will bring a period of light rain across the
southern Catskills, mid-Hudson Valley and northwest Connecticut after
sunset tonight. Farther north, conditions will remain dry through the
night. Monday will be dry, then a weak cold front will approach from
the west bringing a chance of showers with possible thunderstorms
mainly to areas west of the Hudson Valley Monday night, then anywhere
across the area Tuesday.
Maximum relative humidity values will range from 85 to 95 percent late
tonight. Minimum values will fall to 45 to 55 percent on Monday.
Winds will be light and variable tonight, then southerly at 5 to 10 mph
on Monday.
&&
.HYDROLOGY...
Rainfall will be light and spotty across the area through the
middle of this week. Up to a quarter inch of rain could fall in
the lower and mid-Hudson Valley and across the southern
Catskills late tonight, and a cold front could bring scattered
showers and thunderstorms on Tuesday, however most areas will
not receive significant amounts of rain through mid-week. This
will continue to allow for rivers and streams to hold fairly
steady. Many areas from the Hudson Valley eastward are now in
the D0 (Abnormally Dry) to D1 (Moderate Drought) categories in
the latest US Drought Monitor.
The best upcoming chance for some scattered showers and
thunderstorms may be on Thursday with an approaching frontal
system. Any shower or t-storm on Thursday afternoon or evening
could contain some locally heavy downpours.
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...MSE/Wasula
NEAR TERM...MSE/Wasula
SHORT TERM...MSE
LONG TERM...Evbuoma
AVIATION...Evbuoma
FIRE WEATHER...MSE
HYDROLOGY...Frugis
Area Forecast Discussion
National Weather Service Gaylord MI
1145 PM EDT Sun Jul 31 2022
.UPDATE...
Issued at 1019 PM EDT Sun Jul 31 2022
High pressure continues to exit eastward away from Michigan.
Upstream cold front has reached the Minnesota/Wisconsin border...
generating an area of showers and storms along and just ahead of
it. Leading edge of this convection has reached far Western Lake
Superior right on time according to the latest RAP and NAM12. Both
near term models drive this leading edge to our far western CWA by
around 09Z early Monday morning...and then gradually push
convection thru our CWA during the day. Any storms that develop
late tonight will be elevated and instability will be quite
limited into early Monday (MUCAPES under 750 J/kg). Thus...svr
storms are not expected...which agrees with SPC Day 1 Outlook for
general thunder over our CWA. Low temps overnight will cool into
the low to mid 60s.
&&
.NEAR TERM...(Through Tonight)
Issued at 205 PM EDT Sun Jul 31 2022
High Impact Weather Potential: Few non-severe thunderstorms
possible late tonight.
Pattern Synopsis/Forecast: Early this afternoon, quasi-zonal flow is
evident aloft across much of the Great Lakes region while surface
ridging extends from the Northeast into the southern Great Lakes.
Main focus through tonight will revolve around a mid-level
shortwave, currently situated near the Ontario/Manitoba border down
into the northern Plains. Attendant surface low pressure situated
over northwest MN with a cold front draped to the south/southwest
from there. A combination of these features will approach northern
Michigan tonight, eventually bringing more cloud cover along with
shower/storm chances into Monday.
Primary Forecast Concerns: Increasing clouds/PoPs late tonight.
Another banner summer day across northern Michigan this afternoon
with high temperatures well on their way to the mid-upper 80s for
most (of course a touch cooler lakeside and across portions of
eastern upper). Another diurnally/instability driven high-based cu
field out there currently should wane with the loss of daytime
heating/sunlight as we head into this evening, which should leave
initially mainly clear skies under just some passing high clouds.
Low-level jet response increases this evening and especially
overnight in advance of the aforementioned system approaching from
the northwest. Increasing southwest winds will be the rule, most
notably just off the deck -- aiding to transport deep moisture
across the Northwoods (evident by PWs progged to increase to 1.50"+
west of I-75 by 12z Monday). Inherited PoPs for late tonight look to
be on track with chances arriving after 3-4 AM across far western
locales, increasing from there as we head toward the end of the
forecast period Monday morning. By 8 AM, likely PoPs evident areas
west of TVC-CAD, and along/west of M-123 in eastern upper. Some
thunder certainly not out of the question in this initial
shower/storm activity given 500-1,000 J/kg MLCAPE, but given the
elevated nature, nearly a non-existent severe weather threat.
Low temperatures tonight remaining on the mild side...spanning the
&&
.SHORT TERM...(Monday through Wednesday)
Issued at 205 PM EDT Sun Jul 31 2022
High Impact Weather Potential: Thunder possible Monday and again
Tuesday night through Wednesday.
Chances of precipitation will continue through Monday evening as a
cold front associated with an area of low pressure over western
Quebec begins passing through northern Michigan. This will produce
chances of rain/thunder in the warm sector just ahead of the cold
front with continued chances throughout the day as the cold front
moves through northern Michigan. The intensity of any thunderstorms
that do happen to develop will once again depend on the exact timing
of the cold front and residual cloud cover from any convection
tonight/early Monday to inhibit instability. There is around 1000-
1200 J/Kg MUCAPE early Monday morning. If we are able to have some
sunshine Monday and the front is still passing through we could
realize upwards of around 1500+ J/kg MLCAPE. If we do happen to
realize this potential energy we may have to worry about a few
stronger/severe storms Monday afternoon...although at this time
pretty descent cloud cover is progged over northern Michigan. Best
chances would be over northeast lower Michigan. Something to keep an
eye on for future forecasts. High pressure then builds back into the
region for Tuesday...renewing precipitation free weather and nearly
normal temperatures for this time of the year. This high pressure
and precipitation free weather will however be short-lived as
another area of low pressure and strong moisture advection ahead of
the approaching cold front may produce another round of
thunderstorms and possibly some heavy rain that could cause some
minor flooding. Northern Michigan is currently in Day 3 Excessive
Rainfall from WPC. PWATS are progged to exceed 2.00" by Wednesday
afternoon along with MLCAPE in excess of 2000 J/kg. Highest threat
from any strong/severe thunderstorm would be damaging wind and heavy
rainfall.
Southwesterly winds will veer to northwesterly throughout the day
Monday behind the departing cold front. Winds then become fairly
light Tuesday under high pressure, with just a bit of a northerly
component before southwesterly winds begin ramping up Wednesday
ahead of the next approaching cold front with gusts of 25-30 mph
possible during the afternoon hours.
Temperatures will be cooler Monday with the passage of a cold front,
reaching into the low to mid 70s for most, although portions of
northeast lower may make a run to near 80 as that location resides
in the warm sector ahead of the cold front the longest. Tuesday will
warm a bit...reaching into the mid to upper 70s to near 80 and then
80s to low 90s Wednesday with the strong temperature/moisture
advection on southwesterly winds.
.LONG TERM...(Wednesday night through Sunday)
Issued at 205 PM EDT Sun Jul 31 2022
High Impact Weather Potential...Minimal at this time.
Rain chances may linger across portions of northeast lower (mainly
closer to the Saginaw Bay region) early Thursday with the tail end
of the cold front mentioned in the previous forecast period still
passes through. Typical summertime chances of rain appear to remain
through the weekend...but the chances of seeing nothing will be
better than receiving any precipitation as rain chances are very
low...only around 20-30 percent. Temperatures will be much cooler
Thursday and Friday behind the departing system...reaching only into
the mid 70s to low 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1145 PM EDT Sun Jul 31 2022
Low pressure and an associated cold front will swing thru
Wisconsin and Upper Michigan overnight...and then thru Lower
Michigan on Monday. Showers and thunderstorms will develop across
Northern Lower Michigan very late tonight and thru the day on
Monday as this system tracks thru our area. Southerly surface
winds AOB 10 kts overnight will shift to the SW at 10 to 20 kts
and eventually W/NW at 15 to 25 kts on Monday.
&&
.MARINE...
Issued at 205 PM EDT Sun Jul 31 2022
Southwest winds continue this afternoon through at least midday
Monday. While a few gusts to 25 kts remain possible, especially near
Sleeping Bear to Pt. Betsie, gusts to that level should be rather
fleeting. Long southwest fetch over Lake Michigan will build waves
near Seul Choix Pt to 4+ ft this evening with the inherited SCA
continuing. More frequent Small Craft Advisory conditions
anticipated Monday, initially from the southwest through early
afternoon before turning more west-northwesterly behind a cold front
for the afternoon and evening. Scattered showers and storms likely
to accompany this frontal boundary at times very late tonight into
Monday as well.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT from 8 AM EDT Monday through Monday
evening for MIZ020-025-098-099.
LH...NONE.
LM...SMALL CRAFT ADVISORY until 4 AM EDT Tuesday for LMZ323-342-
344>346.
SMALL CRAFT ADVISORY until 4 AM EDT Tuesday for LMZ341.
LS...NONE.
&&
$$
UPDATE...MLR
NEAR TERM...MJG
SHORT TERM...TJL
LONG TERM...TJL
AVIATION...MLR
MARINE...MJG
Area Forecast Discussion
National Weather Service Birmingham AL
618 PM CDT Sun Jul 31 2022
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
/Updated at 105 PM CDT Sun Jul 31 2022/
Through Monday.
Subtropical mid-level ridging persists over the Southwest
Atlantic Basin and extends west over the Wiregrass portion of the
state, while persisting ridging aloft is centered over Western
Texas. A longwave trough extends from over South-Central Canada
and extends south into the Mid Mississippi River Valley region.
A weak surface boundary continues to retreat northward further
away from the area across the Tennessee Valley region while a weak
surface trough was analyzed near the Interstate 20 corridor.
Surface high pressure was positioned to the east of the Florida
peninsula.
A few storms today may produce gusty winds due to some drier air
in the mid levels. The wet microburst risk is on the lower end of
the moderate range. Relatively slow storm motions coupled with
moist low-level conditions will support heavy rainfall in the
heavier activity today. With some spots receiving over an inch of
rain yesterday, there will be potential for some water ponding,
especially in low-lying, urban and poor drainage areas.
Today.
A weak trough roughly parallel to I-20 is supporting isolated to
scattered showers that are developing across the northern third of
the forecast area. Meanwhile, drier air aloft was moved in from
the east across the South/Southeast areas and this is resulting in
fair skies in these areas. Slow moving showers and storms are
located to our northwest from Northern Mississippi into Western
Tennessee. This activity appears to be aided by divergent flow
aloft as depicted in RAP modeling. Showers are developing ahead of
this activity at this writing across Northeast and East-Central
Mississippi and expect this trend to continue. Rain chances will
increase later this afternoon across the north and northwest as
the activity to the northwest approaches the area. Winds today
will be from the southwest at 5-10 mph. Highs will upper 80s north
to the mid 90s south.
Tonight.
Mid-level ridging will remain over the far southeast while the
longwave trough moves east over the Ohio and Tennessee River
Valley regions. Showers with a few storms will diminish with time
as best chances for activity will linger across the northern
portion of the area. Moisture in the lower levels will support
some patchy fog and low cloud development before sunrise Monday
morning. Winds will be light and variable. Lows will range from
near 70 in the higher elevations east to the lower 70s south and
west.
Monday.
As the longwave trough continues moving east over the Ohio and
Tennessee River Valley regions, most modeling depicts a shortwave
disturbance moving east over the northern portion of the state
from mid morning through midday. The result will be increasing
clouds across the northern and western sections with chances for
showers and some thunderstorms rising during this time frame and
persisting into the afternoon hours. Winds will be from the west
at 5-10 mph. Highs will range from the upper 80s northwest to the
mid 90s south.
05
.LONG TERM...
/Updated at 0309 PM CDT Sun Jul 31 2022/
Ridging remains dominant across the southern CONUS, keeping the
main shortwave/storm track to our north. Weaknesses in the ridge
will help guide rain chances through the extended, with chances
during most periods. No significant changes are needed this
afternoon.
14
Previous long-term discussion:
/Updated at 0337 AM CDT Sun Jul 31 2022/
Tuesday through Saturday.
Warm and humid conditions expected through much of the upcoming
week.
The Bermuda High will continue to be the main feature across the
Southeastern CONUS with generally weak flow aloft. The lingering
upper level energy from the previous trough axis will persist just
to our south, providing some focus for higher thunderstorm chances
across the southern half of central AL.
Broad ridging builds in across the Great Plains towards the end of
the week, which should lead to gradual warming trend for us in
Central AL. With the humid air mass persisting, heat indices will
likely trend upwards as well with values approaching triple digits
by the weekend.
25/Owen
&&
.AVIATION...
00Z TAF Discussion.
Convective activity will continue for areas north of I-20 thru
03z. Current radar trends keep the tstms just outside the 10 mile
range for the TCL/BHM airports, and will not include any weather
for these two TAF sites in the early portion of the TAF period.
VFR conds expected thru the period with no cig or vsbys issues. A
layer of relatively drier air spread across south Alabama today,
and this should keep lower cigs across far north Alabama overnight.
Re-development of showers and tstms expected Monday afternoon,
and handled with PROB30 groups.
58/rose
&&
.FIRE WEATHER...
Scattered to numerous showers and thunderstorms expected the next
couple of days, with the activity focused across the north on
Monday and south on Tuesday. 20ft winds remain out of the
west through early next week, but less than 10mph. Min RHs will
be near or above 50% for most of the area through the next few
days.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 71 88 71 90 70 / 50 60 20 50 20
Anniston 71 89 72 89 71 / 20 50 20 50 20
Birmingham 74 91 74 90 72 / 30 50 20 60 20
Tuscaloosa 73 92 74 91 72 / 20 50 20 60 20
Calera 72 91 73 89 73 / 20 40 20 60 20
Auburn 73 91 73 89 72 / 10 30 20 60 20
Montgomery 74 95 74 92 73 / 0 30 20 60 20
Troy 73 94 73 91 72 / 0 30 20 70 20
&&
.BMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Cleveland OH
932 PM EDT Sun Jul 31 2022
.SYNOPSIS...
Low pressure will move through the northern Great Lakes tonight
and Monday dragging a weak cold front through the area late
Monday. High pressure will briefly return Tuesday before the
front comes back north as a warm front by Wednesday ahead of
another cold front by Thursday.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
Added in mention of a few areas of patchy fog overnight across
the southeast portion of the area near the OH/PA border where
lower wind speeds will reside.
Previous Discussion...
The pesky little surface low has now exited across PA allowing skies
to become mostly sunny. The lower Great Lakes and Ohio Valley region
will be in between systems this evening and tonight as we await the
approach of a mid/upper shortwave trough currently located over
North Dakota and Minnesota. This will lead to a pleasant evening,
although increasing warm air advection will continue to gradually
increase dew points tonight making it feel more on the muggy side.
This will hold low temperatures in the low/mid 60s tonight.
The aforementioned mid/upper shortwave will continue east into the
western Great Lakes Monday morning and into the eastern Great Lakes
by Monday night, slightly deepening a trailing longwave trough in
response across the Great Lakes region. The associated surface low
will track from north of Lake Superior Monday morning across
southern Hudson Bay early Monday night dragging a cold front across
our region Monday evening into Monday night. Ahead of the front, a
continued increase in warm/moist advection will pull a much more
moisture rich airmass into the region as a diffuse warm front lifts
through the area by afternoon. Dew points should pool in the low 70s
by mid to late afternoon in the warm sector as the trailing cold
front approaches, and what looks like a decent amount of sunshine
will boost afternoon temperatures into the mid/upper 80s. The
combination of the increased heat and humidity, large scale ascent
ahead of the approaching mid/upper shortwave and associated PVA, and
low-level convergence ahead of the cold front will trigger a broken
line of thunderstorms which will cross the region from west to east.
Timing among the latest HREF members suggests initiation in NW Ohio
in the 16-18Z timeframe, with the convection then crossing north
central Ohio between 20 and 23Z and far NE Ohio and NW PA between 21
and 01Z. However, added chance PoPs in NW Ohio with this forecast
package starting around 15Z since NAM and RAP forecast soundings
suggest very little capping, so it is possible to see some activity
farther east a couple of hours sooner as well.
In terms of severe potential, I am not very impressed. This looks
like the makings of a typical August scattered thunderstorm event
ahead of a cold front where most areas will see brief heavy rain and
thunder/lightning, and a few storms could be locally severe with
damaging downburst winds and localized flooding, but nothing
widespread. There are several reasons for this. First, the greatest
upper level dynamics are lagging behind the cold front across the
northern and central Great Lakes causing H3 winds to only average 40-
50 knots and H5 winds to only average 35-40 knots across our region
in the warm sector Monday afternoon and evening. This limits deep
layer (0-6 Km) shear to generally 25-30 knots, 0-1 Km shear to 15-20
knots, and effective shear to 30-35 knots. These are very marginal
values and point to vigorous updrafts not being sustained for long.
Second, abundant warm air aloft, typical for August, will limit mid-
level lapse rates to 6 to 6.5 C/Km which is okay, but not great. The
tongue of steeper mid-level lapse rates will be confined to Indiana
and far western Ohio, so the result is MLCAPE values being limited
to 1000-2000 J/Kg in much of north central and NE Ohio into NW PA in
the afternoon and evening, with better 2000-3000 J/Kg values over
the far western and southwestern counties. However, these higher
MLCAPE values are displaced from the greater shear which will be
near Lake Erie. In summary, the shear is very marginal, and the best
instability is displaced from the better shear. Despite these
negatives, it is August, so these hot and moist low-level airmasses
do trigger a few severe storms with damaging winds, and this will be
the case tomorrow as forecast soundings indicate some mid-level dry
air entrainment to enhance downdraft potential (DCAPE values at
least over 900 J/Kg), so the SPC upgraded to a Slight Risk in their
SWODY2 from parts of Wood and Sandusky Counties southeast through
parts of Richland and Ashland Counties and points south from there.
In terms of heavy rain potential, the relatively brief period of
strong warm air advection before the cold frontal passage limits
PWATs to 1.30 to 1.65 inches, and a low-level jet veering more WSW
by evening (more perpendicular to the front) should allow for fairly
quick movement without much training. The orientation of shear
vectors suggest west-east progressing multicell clusters, so any
flash flood threat will be isolated to urban and poor draining
areas.
Most areas will dry out behind the cold front Monday night as
sprawling surface high pressure builds in from the western Great
Lakes, but the front slowing down in far eastern Ohio and western PA
in response to a building mid/upper ridge in the Plains/Mississippi
Valley will cause showers and thunder to linger there longer, so
held onto chance PoPs through the night. Lows Monday night will stay
in the mid/upper 60s.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Fair weather is likely Tuesday through Tuesday night as high
pressure at the surface and aloft builds eastward across our CWA.
Late afternoon highs should reach the lower to mid 70`s in northwest
PA and the mid 70`s to mid 80`s in northern OH. Overnight lows
should settle into mainly the mid 50`s to mid 60`s Tuesday night.
The coolest lows should be concentrated in interior northwest PA and
far-northeast OH, while the warmest lows should be concentrated in
our I-75 corridor counties. Our weather becomes much warmer and more
humid Wednesday through Wednesday night as the high pressure ridge
at the surface and aloft exits eastward and a trough aloft and
accompanying surface cold front approach from the Upper Midwest and
western Great Lakes. This pattern will promote low-level warm and
moist air advection from the Gulf of Mexico. This advection pattern
combined with daytime heating will promote moderate to perhaps
strong boundary layer destabilization during the afternoon and early
evening. Boundary layer CAPE should then wane to weak magnitudes
later Wednesday evening and overnight as some nocturnal cooling
occurs. Isolated to scattered showers and thunderstorms are possible
ahead of the front, especially Wednesday afternoon and evening,
given the forecast diurnal range in instability, including MUCAPE.
Late afternoon highs should easily reach the upper 80`s to mid 90`s
and be followed by balmy lows in the mid 60`s to mid 70`s overnight
Wednesday night.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Scattered showers and thunderstorms are likely on Thursday when the
aforementioned surface cold front is progged to sweep southeastward
through our CWA and encounter a sufficiently-humid and unstable
boundary layer, and the associated trough aloft overspreads our
region from the western Great Lakes. Daytime highs should reach the
mid to upper 80`s prior to the front`s passage. Periodic isolated to
scattered showers and thunderstorms should occur Thursday night
through this weekend as the trough aloft becomes entrenched over our
area due to a blocking downstream ridge aloft over/near the U.S.
East Coast. Given the cooler air aloft associated with the trough,
self-destructive sunshine should act as the primary trigger for
convection development. Therefore the potential and coverage of
showers and storms should be maximized each afternoon and early
evening due to the typical diurnal range in surface air temperatures
and instability. At the surface, the core of a high pressure ridge
near Lake Superior Thursday night should eventually be absorbed by
the Bermuda-Azores subtropical ridge as surface ridging affects our
region. Overnight lows should reach mainly the 60`s Thursday night
through Saturday night. Daily highs should reach the upper 70`s to
lower 80`s on Friday and the 80`s this weekend.
&&
.AVIATION /00Z Monday THROUGH Friday/...
VFR across the TAF sites this evening with generally VFR to
persist through the TAF period, though pockets of MVFR and
perhaps IFR associated with thunderstorms are possible towards
the end of the TAF period. Isolated to scattered thunderstorms
will develop along and ahead of a cold front tomorrow afternoon
and evening, though uncertainty remains on coverage and eventual
impacts on individual TAF sites. Thus, have generally kept the
vcts mention across all TAF sites, with a 2-hour prob30 addition
at CLE from 23-01Z for -tsra.
Winds are generally from the south this evening, around 5 knots,
with the exception of a lake breeze at CLE/ERI which will shift
back around to the south over the next couple of hours. South to
southwest winds will increase tomorrow afternoon into the 10 to
15 knot range with gusts of 20 to 25 knots possible. Behind the
cold front tomorrow evening, winds will shift towards the west
and northwest, 10 to 15 knots with gusts around 20 knots
possible.
Outlook...Non-VFR possible in lower ceilings Monday night into
Tuesday morning across NE OH and NW PA. Non-VFR possible in
showers and thunderstorms Wednesday night through Thursday.
&&
.MARINE...
As a high pressure ridge departs eastward, light and variable winds
today become southerly to southwesterly at about 10 to 15 knots
tonight into Monday. Waves should trend 3 feet or less in U.S.
waters. Southwesterly winds of about 15 to 20 knots shift to
northwesterly Monday night as a cold front sweeps eastward across
Lake Erie. Waves of 2 to 4 feet are expected, especially in the
central and eastern basins. A Small Craft Advisory may be needed,
especially east of Avon Point.
Another high pressure ridge should build eastward across Lake Erie
on Tuesday and be accompanied by northwesterly winds of about 10 to
15 knots in the morning, becoming light and variable later in the
day. Waves should subside to 2 feet or less. The ridge should begin
to exit eastward Wednesday through Wednesday night. Primarily
southerly to southwesterly winds of about 10 to 17 knots are
expected on the backside of the ridge. Waves should be 3 feet or
less, but occasional 4 footers are possible in open waters of the
central and eastern basins. Another cold front should sweep
southeastward across Lake Erie on Thursday and cause southwesterly
winds of about 10 to 15 knots to shift toward northerly. Winds
should then become northerly to northeasterly on Friday as high
pressure builds from the Upper Great Lakes. Waves should be 3 feet
or less.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Garuckas
NEAR TERM...Garuckas/Kahn
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...Kahn
MARINE...Jaszka
Area Forecast Discussion
National Weather Service Grand Rapids MI
1040 PM EDT Sun Jul 31 2022
LATEST UPDATE...
Update
.UPDATE...
Issued at 1040 PM EDT Sun Jul 31 2022
Decent coverage of storms upstream currently over wrn WI/MSP and
these are still expected to arrive in wrn Lwr MI shortly before
daybreak. Coverage of convection may tail off a bit between now
and daybreak as instability wanes, but should increase again
overhead by mid morning as instability rebuilds.
Latest RAP/HRRR Fcst soundings for 15Z Monday just ahead of the
front are a bit concerning, showing MLCapes near 1500 J/KG and
decent deep layer shear near 35 kts. There`s even good shear down
low, with Sfc-1 KM SRH of 100-150 m/s and curved low level
hodographs.
The 0-3KM cape prog from the RAP shows 800-1200 J/KG near and
south of I-96, so good buoyancy down low too. This occurs as lower
70s sfc dew points are sneaking in ahead of the sfc front and mid
level shtwv, which also leads to low LCL heights.
It appears that a low end tornado risk could exist in this
environment if stronger sfc-based storms can develop before
fropa, but that`s still a big if. The new 00Z NAM coming in now
is not as bullish as RAP/HRRR with sfc based capes. Still this
bears watching. The main time frame of concern would be roughly
10 AM to 3 PM.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 316 PM EDT Sun Jul 31 2022
--Showers possible tonight, Monday--
Currently, a cold front extends south from a low over northwest
Minnesota. Dewpoints ahead of the front are in the upper 60s/lower
70s and we`ll see that moisture take aim at SW Lower later tonight
and Monday. Precipitable water value trends have increased a bit
with the latest model runs and now are closing in on 2 inches by
12z. We`ll probably see showers and perhaps a thunderstorm move east
from Wisconsin late tonight, but would expect most of the
thunderstorms to be north of the cwa, closer to the short wave.
Shear values increase Monday to around 35 knots. There will be a
window during the afternoon, where the southeast cwa may see enough
instability develop to take advantage of the moisture supply and
stronger mid level winds to produce stronger storms. The remnants of
overnight convection will go a long way in determining how much the
atmosphere is able to recover.
-- Heat Wednesday, followed by the potential for heavy rain--
The GFS shows a weak signal for a few storms Tuesday night, mainly
from a short wave moving through. However, the ECMWF and NamNest
haven`t bought into that yet. A strong surge of low level moisture
will push dewpoints into the lower 70s Wednesday, that when combined
with highs in the lower 90s will yield heat indices in the upper
90s; a Heat Advisory may be needed Wednesday.
Precipitable water values increase to over 2 inches Wednesday.
Storms firing along the cold front late Wednesday will encounter a
strengthening low level jet and will be capable of producing heavy
rainfall. Mid level winds more parallel to the front may give a nod
to the slower ECMWF solution which keeps precipitation over the cwa
through Wednesday night.
--A bit cooler late in the week--
Thursday and Friday will see cooler temperatures; highs around 80.
However, given dewpoints remaining in the 60s, the air will feel
humid. We may see showers/storms move over the cwa again Sunday
ahead of another cold front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 800 PM EDT Sun Jul 31 2022
VFR weather will continue much of tonight although after 09Z the
threat/coverage of showers and tstms will ramp up from west to
east. Any terminals impacted by heavier rainfall rates early
Monday morning could see some brief periods of MVFR or lower vsbys
with these showers/storms.
About a 6 hour period of MVFR cigs is anticipated with the cold
frontal passage on Monday, mainly between 12Z and 18Z. Conditions
trending toward primarily VFR after 18Z Monday as showers end and
cigs lift and/or scatter out behind the front.
South winds less than 10 kts expected much of tonight, but
increasing after 09Z as the front approaches from the west. MKG
should turn particularly windy by 12Z Mon with gusts to 30 kts
possible. Winds shifting westerly 15-25 kts and gusty behind the
front for Monday afternoon.
&&
.MARINE...
Issued at 316 PM EDT Sun Jul 31 2022
No changes to the marine headlines. We expect low level winds to
increase tonight ahead of an approaching cold front. Winds will
increase after 09z before beginning to decrease by early afternoon.
Waves will take a few hours longer to subside.
Another Small Craft Advisory and Beach Hazards Statement may be
needed Tuesday night and Wednesday ahead of another cold front.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from 6 AM EDT Monday through Monday
evening for MIZ037-043-050-056-064-071.
LM...Small Craft Advisory from 2 AM to 11 PM EDT Monday for
LMZ844>849.
&&
$$
UPDATE...Meade
DISCUSSION...04
AVIATION...Meade
MARINE...04
Area Forecast Discussion
National Weather Service Wilmington NC
815 PM EDT Sun Jul 31 2022
.SYNOPSIS...
Shower and thunderstorm activity will continue through early
this evening, as an old frontal boundary slowly lifts north to
southern Virginia. A summerlike pattern can be expected during
the upcoming week, with high pressure situated off the Carolina
coasts with a chance of showers and thunderstorms each afternoon
and early evening.
&&
.UPDATE...
Latest HRRR illustrates a lack of convection overnight as the
best dynamics associated with the warm front lift further north
of the local area overnight. Subsidence across the area,
especially across the ILM SC Counties where sfc dewpoints have
dropped temporarily into the 60s. Will see occasional mid and
high level convective debris clouds this evening that should
thin out to just thin cirrus overnight into daylight Mon.
&&
.NEAR TERM /THROUGH MONDAY/...
Latest surface analysis shows an old frontal boundary just north
of the NC Triad, trying to edge its way into southern Virginia.
Showers and storms have popped up this afternoon with help of
this boundary. Some of these storms have been severe well to the
north of northeast South Carolina and southeast North Carolina,
but the good news is that the scattered activity around here has
not been as threatening.
Expecting widely scattered showers and storms to continue
through this afternoon, before leveling off soon after sunset
this evening. Slight SSW breeze expected tonight, which should
help us avoid widespread fog early Monday morning. Lows in the
mid-to-upper 70s.
It took awhile, but forecast guidance is finally in good
agreement on how Monday turns out. Base of mid-level shortwave
trough looks roughly bisect the forecast area, which had been
the overall suspicion the last few days (as opposed to some
guidance having the base dip much farther south). Smaller
shortwaves traverse along this broader feature throughout the
day. Seeing some better shear vorticity along the northern half
of the area, and have kept a modest chance of afternoon showers
and storms. However, stacked Bermuda ridge will try to argue
this idea. Mid-level dry air infiltrates the column, and one or
two inversions may keep the atmosphere capped throughout the
day. Either way, keeping rain chances considerably lower along
the coast. Highs in the low-to-mid 90s again.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
A weak mid/upper trough, along with a band of higher PWATs,
across the forecast area will support carrying some POPs into
Monday evening. During Tuesday a weak surface trough may become
situated across the forecast area, and the seabreeze will likely
become active as well. Best chances across most areas will be
Tuesday afternoon/evening. However, with the highest PWATs
displaced off the coast any convection will likely remain
scattered versus numerous. Otherwise, southwesterly flow will
maintain above normal lows (generally mid 70s) each night, and
above high temperatures (mid 90s inland areas) during Tuesday.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A weak surface trough will become established farther inland
during Wednesday while the weakness aloft between subtropical
ridges drifts toward the west. As a result, expect scattered
diurnally driven convection with the weak surface trough and
seabreeze front to provide some focus, with the best chances
across inland areas. GEFs suggest the aforementioned weakness
aloft will be a little farther west than the operational run by
Thursday. Additionally, the axis of higher PWATs should shift
westward as well with the best chances across the far inland
zones. Similar conditions are expected Friday. Increasing
coverage of afternoon/evening convection is possible during the
upcoming weekend with the weakness between the subtropical
ridges shifting back toward the east. Max/min temperatures will
continue to be above through mid-week, then near normal highs
the latter half of the week into the weekend.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Convection has ended across southeast NC and northeast SC...and
as a result have removed remaining thunderstorm activity across
all terminals this evening. Will deal with mid and upper level
convective debris clouds this evening that should thin out to
just high level cirrus by daybreak Mon. Expect a more typical
summer time chance for convection from mid-afternoon into the
evening and have only mentioned vcts for each terminal. S to SW
winds remain active overnight, keeping fog development at bay at
all terminals. Winds become active WSW-W and gusty during Mon as
the sfc pg tightens-some overnight thru Mon. In addition,
active WSW winds in the low levels will keep a somewhat pinned
sea breeze, with winds only backing to SSW-SW direction at
MYR/CRE and may take until late aftn for ILM to observe the sea
breeze passage.
Extended Outlook...Low chance for patchy MVFR/IFR low stratus
and/or ground fog mainly inland terminals around sunrise each
morning. Periodic MVFR/IFR expected with isolated to scattered
showers and thunderstorms each aftn and evening through the
upcoming week.
&&
.MARINE...
Through Monday...A breezy but overall benign marine period
here. Southwesterly flow continues over the waters, with winds
at 15-18kts with gusts up to 20-23kts. Main southerly swell at
2-3ft at 5 seconds, with a secondary southeasterly swell
clocking in at 8-10 seconds.
Monday Night through Friday... SWly flow will persist Monday
night through much of the forecast period (outside of any
convection) as surface high pressure of the Carolinas coast
dominates the larger scale flow. Speeds will ebb and flow
diurnally with the seabreeze circulation each day. Seas will
average 2-4 ft through most of the extended time frame, but will
be choppy at times, especially each afternoon and evening.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...ILM
UPDATE...DCH
NEAR TERM...IGB
SHORT TERM...SRP
LONG TERM...SRP
AVIATION...DCH
MARINE...IGB/SRP
Area Forecast Discussion
National Weather Service Lincoln IL
911 PM CDT Sun Jul 31 2022
.SYNOPSIS...
Issued at 610 PM CDT Sun Jul 31 2022
A warm front will bring warmer and more humid air back into the
region tonight through much of the upcoming week. A weather system
will bring a chance of showers and thunderstorms late tonight and
Monday with a risk of strong to severe storms south of I-72
Monday afternoon and evening. Heat index values will likely reach
dangerously hot levels this week, peaking around 105 Wednesday
afternoon.
&&
.UPDATE...
Issued at 911 PM CDT Sun Jul 31 2022
An approaching cold front, currently producing convection near the
I-35 corridor in northern IA/southern MN is the main feature of
interest overnight. Ahead of the front, warm and moist air will
continue to overspread central IL late this evening. Dewpoints
should be into the lower 70s by early morning. A low level jet and
warm advection aloft could initiate scattered showers ahead of
the main convective line, as hinted at by several recent CAM
solutions. In fact, the latest 00Z HRRR run essentially
disorganizes the line by the time it reaches the IL River Valley
in favor of scattered showers/thunderstorms reaching all the way
past I-70 by 12Z. For now, this seems a plausible solution and
supported by a couple of runs now. Have updated forecast for an
earlier, and broader coverage to showers in the early morning as a
result. Otherwise, lows near 70 seem on track for tonight.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 300 PM CDT Sun Jul 31 2022
Mid afternoon surface analysis shows a warm front lifting ne into
central IL with muggier dewpoints in the mid 60s to around 70
degrees. Scattered showers and isolated thunderstorms are south of
I-64 with our CWA generally dry so far today with variable cloud
cover. Temps were in the upper 70s/lower 80s with Peoria at 85F.
Latest CAMs show isolated convection possible south of a Effingham
to Robinson line into early evening until sunset so continued
slight pops in southeast IL. Focus then shifts to our nw with cold
front pushing se toward the IL river valley by 12Z/7 am Monday and
bringing chance of convection into areas from Peoria nw late
tonight. Models still differ with evolution of this band of
convection which would occur with the cold front as it pushes se
over portions of central IL during Mon morning. Think this may be
a weakening state with this band of convection and models
generally keeping it over ne CWA Mon morning and some even dry
over CWA Mon morning. Convection should redevelop during mid/late
Monday afternoon as it moves se with cold front into southeast IL
and pushes se of Lawrence county by 00Z/7 pm Mon. SPC day2 has
marginal risk for damaging winds from Rushville to Bloomington
south Mon afternoon, and feel this severe threat may be focused
further south of I-72 where moderate to strong instability CAPEs
peak at or above 3000 j/kg and moderate wind shear of 30-35 kts.
Downdraft CAPE values are about 1200 j/kg while high freezing
levels may limit large hail production. PW values of 1.5-2 inches
Mon afternoon south of I-72 so moderate to heavy rainfall possible
with thunderstorms that occur.
Lows tonight in the lower 70s, with some upper 60s in east
central IL. Highs Monday in the upper 80s to lower 90s. Dewpoints
pooling in the mid to upper 70s Mon afternoon in southeast IL to
give heat indices peaking from 100 to 105 degrees from I-70 south
before cold front and possible convection passes through by late
afternoon.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 330 PM CDT Sun Jul 31 2022
Convection chances diminish in southeast IL after sunset and
carried slight chance of showers/thunderstorms south of I-74
Monday night. Weak high pressure ridge shifts east of IL on Tue
morning with return south flow developing during the day Tue and
returning hot and humid weather and isolated convection possible.
Highs Tue in the upper 80s and lower 90s, with dewpoints rising
into the low to mid 70s by Tue afternoon. Heat indices Tue
afternoon to rise to near or just above 100F sw CWA and southeast
IL, while SW IL could see Heat indices approaching 105F.
A stronger wx system to move se toward nw IL Wed afternoon and
will see breezy SSW winds bring a hot and humid day to the area
with highs in the low to mid 90s and heat indices of 105F or
higher over much of CWA. A heat advisory will likely be needed
then. Have 30-40% chance of thunderstorms by late Wed afternoon
from IL river nw with 20% chance as far southeast as I-72 by 00Z/7
pm Wed. The frontal boundary to push se into central IL during Wed
night likely bringing showers and thunderstorms. Could be chance
of strong to severe storms Wed night with high instability ahead
of cold front Wed afternoon/evening. PW values rising to 2-2.5
inches to also give risk of heavy rains Wed night.
Medium range models keep high chances of showers and thunderstorms
on Thu especially east of the IL river, while chance of showers
and thunderstorms linger in southeast IL Friday as front moves se
over the Ohio river valley/KY. Cooler highs Thu in the mid 80s
and lower 80s Friday. Subtropical ridge builds into IL this
weekend (500 mb heights rise to near 594 dm or higher) and likely
builds the summertime heat and humidity back into the area. Highs
in the mid to upper 80s Saturday and upper 80s to near 90F next
Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 624 PM CDT Sun Jul 31 2022
A chance of showers and thunderstorms will develop from 10Z-12Z
until 15Z-19Z across most of the central IL terminals, with
chances lowest toward the southwest including KSPI. Otherwise, VFR
conditions conditions are expected for most of the period,
although some isolated MVFR cigs are possible through 02Z and some
isolated MVFR cigs/vsbys are possible with any thunderstorms
Monday morning/early afternoon. Winds S 8-10 kts overnight,
becoming W-NW 10-15 kts with gusts around 20 kts behind a cold
front, after 15Z-19Z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...37
SYNOPSIS...37
SHORT TERM...07
LONG TERM...07
AVIATION...37
Area Forecast Discussion
National Weather Service Indianapolis IN
1052 PM EDT Sun Jul 31 2022
...Updated Aviation Discussion...
.Forecast Update...
Issued at 957 PM EDT Sun Jul 31 2022
The recent HRRR runs have trended quicker bringing in Minnesota and
Iowa convection and have a good handle on the current spatial and
temporal aspects. Chatting with ILX, LOT and IWX, decided to bring
chance PoPs into the Wabash Valley 09z-12z. Plenty of instability
with MU CAPES to 1000 or so J/Kg moving in along with 50 knot upper
speed max over lower Michigan and a modest 30 knot low level jet
approaching.
&&
.Short Term...(This evening through Monday night)
Issued at 252 PM EDT Sun Jul 31 2022
* Chance of showers and thunderstorms on Monday
* Isolated severe potential south and east
Rest of Today and Tonight
Cloud cover is gradually increasing this afternoon as a shortwave
trough makes its way through Indiana. Showers earlier today across
our southern counties have mostly come to an end. A few light
returns on radar have been occasionally noted over Knox and Daviess
counties. Will maintain slight PoPs across the south.
A surface low currently over northern Minnesota will move across the
Great Lakes overnight, dragging a cold front southeastward. This
front will approach the region late tonight or even early Monday.
There remains some disagreement within the CAMs regarding upstream
convection. A few models depict convection persisting along the
boundary into the night and entering our CWA early in the morning.
There is some credence to this scenario, as a strengthening low-
level jet and strong moisture advection may allow a pre-existing
convective system to sustain southeastward. The greatest likelihood
for morning showers and storms would be in our northern and
northwestern counties. Should a convective system sustain itself
overnight, it will likely be weakening as it approaches...gradually
dissipating Monday morning as the LLJ diminishes.
Monday and Monday Night
The cold front itself should continue towards central Indiana Monday
morning as well. There is good agreement within the various models
showing showers and thunderstorms redeveloping along this boundary.
However, decent model spread regarding the evolution of these storms
remains. The possibility of lingering morning convection may play a
role determining how the afternoon convection plays out.
Should morning convection be present, lingering cloud cover and cold
pools may hold down instability. Additionally, these areas of
differential heating may allow any remnant outflow boundary to
become a focal point for renewed convective initiation. Some earlier
HRRR runs have shown such a scenario unfolding, as well as the NSSL
WRF. Should morning convection not persist into our CWA, a more
pristine environment can exist for afternoon convective development.
Any development would be concentrated along the cold front itself,
which could organize into multicells or perhaps an embedded
supercell given a shear vector initially perpendicular to the
boundary. This scenario is best represented in recent 3km NAM runs.
Model soundings characterize the pre-frontal environment with
moderate shear and instability, roughly 30 to 40 kts and 3000 J/kg
respectively. A fairly wide CAPE profile within the hail growth
zone, along with strong upper-level flow, may allow for some
instances of large hail. However, fairly high freezing levels should
limit the hail threat to the strongest cells. Dry air aloft, mainly
above 700 mb, gives the potential for strong cold pools and
downdrafts. Model soundings indicate as much as 1500 J/kg DCAPE.
Given the dry and relatively fast mid-level flow, strong to damaging
wind gusts could easily be transfered down to the surface. Compared
to the hail potential, damaging winds appear to the be primary
threat.
Additionally, a conditional low-probability flooding potential
exists as southwesterly winds promote storm regeneration /
propagation towards the southwest. Cold pools should spread
southeastward, while convection preferentially redevelops on the
southwest side...allowing the resulting convective system to become
more shear parallel. This could lead to training storms and an
increased chance of flooding.
One potential limiting factor for thunderstorm potential is a warm
layer around 850mb. This modest cap could inhibit convection until
late in the afternoon, which may allow the front to make it most of
the way through our CWA before convection finally is able to
initiate. That would place the best chance of storms in our eastern
and southern counties.
&&
.Long Term...(Tuesday through Sunday)
Issued at 252 PM EDT Sun Jul 31 2022
- Warming and dry on Tuesday and Wednesday
- Rain chances Wednesday Night through Sunday
Tuesday through Wednesday...
Northwest flow aloft is expected to be pushed farther northeast on
Tuesday and Wednesday as a strong area of high pressure in place
over the American Southwest pushes a ridge axis aloft east and
builds across the Ohio Valley. Subsidence appears in place across
Indiana on Tuesday and Wednesday aloft as surface high pressure
found SE of Indiana allows a warm and humid southerly flow into the
Ohio Valley. Thus will aim for mostly sunny days and mostly clear
nights along with hot temperatures. Once again highs should be in
the lower 90s..
Wednesday night through Sunday...
Models suggest a strong area of high pressure will settle over the
American southwest and western plains, once again allowing the
development of NW flow aloft over Central Indiana. An upper level
trough and short wave is expected to push toward Central Indiana on
Wednesday night before becoming stalled across Indiana, OH and the
eastern Great Lakes on Thursday through Sunday. Within the lower
levels a stalled surface front will linger beneath this upper
trough, providing a focus for surface convergence each day through
Sunday. Mid levels hint at sufficient moisture lingering within the
trough area. Meanwhile forecast soundings show attainable convective
temperatures with sufficient CAPE and moisture available to trigger
diurnal showers and perhaps a storm. Thus will include daily pops
during this time given the favorable ingredients for precipitation
shown.
&&
.Aviation...(00Z TAF Issuance)
Issued at 1051 PM EDT Sun Jul 31 2022
Impacts:
- VFR Conditions are expected to deteriorate to MVFR and worse
after 09z due to developing low stratus.
- Thunderstorms possible after 09z and through 17z at KLAF and
later over the other sites.
- Winds 200-230 degrees less than 10 knots overnight and increasing
to 10 to 15 knots with gusts around 20 knots after 17z. Finally,
winds will shift to 270-310 degrees 10 knots and less in the
wake of a cold front after 18z.
Discussion:
A cold front will drop southeast across the terminals this
afternoon. The front will interact with a warm, humid and unstable
atmosphere and result in afternoon convection. Prior to that, VFR
flying conditions will deteriorate to MVFR and worse toward daybreak
as an inversion sets up atop a moist boundary layer and results in
stratus development. Also, Minnesota and Iowa convection may reach
KLAF and KHUF 09z-12z, so added VCTS there.
Winds will be southwest 10 knots or less overnight and increase to
10 to 15 knots with gusts to around 20 knots this afternoon. Winds
will then shift to the west and northwest in the wake of the cold
front, late this afternoon and evening.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...MK
Short Term...Eckhoff
Long Term...Puma
Aviation...MK
Area Forecast Discussion
National Weather Service San Francisco Bay Area
903 PM PDT Sun Jul 31 2022
...Isolated Thunderstorms Possible tonight into Monday...
.SYNOPSIS...Isolated high-based thunderstorms are possible tonight
into Monday as mid/upper level moisture advects northward across
the region. Otherwise, seasonable weather conditions will prevail
across the region with inland areas heating up by midweek.
&&
.DISCUSSION...as of 09:00 PM PDT Sunday...
It`s an active evening across the West with a dirty high pressure
system extending from the southern Great Basin through the Four
Corners region and an upper low off the NorCal coast. Tropical
Cyclone Frank was also churning well offshore from Baja. The low
pressure system has created a weakness within the upper ridge and
was allowing rich mid-upper moisture associated with the
Southwestern Monsoon to migrate into our area on southeasterly
winds aloft. Precipitable water values have already increased
appreciably with the 01.00z OAK sounding exhibiting a daily-
record-breaking value of 1.62 inches. For reference, the daily
evening mean is 0.75 inches with the 90th percentile value being
1.03 inches. However despite this high value a notable dry layer
was present below 500 mb with a very large dewpoint depression.
Scattered high-based showers that developed today have produced
very little in the way of rainfall and this sounding profile
really illustrates the reason why.
As we head through the overnight hours forecast models suggest
some deepening of the moist layer as 700 mb relative humidity
values increase to around 75 percent across the Central Coast.
With time this moistening should make its way farther north into
the Bay Area later in the morning/afternoon on Monday. Some
instability will accompany this moisture push as weak vorticity
ripples rotate anticyclonically around the upper ridge. So it does
appear we`ll be able to get a little more shower action for the
remainder of the night into Monday. But the question is:
will we get thunder? I`d like to say that confidence is
appreciably higher from yesterday but unfortunately this remains a
conditional setup. Things do look decent on the moisture front.
However the rather amorphous forcing for ascent and so-so mid-
level lapse rates do give a bit of pause. That said it`s hard to
ignore the impressive elevated instability shown among high-
resolution guidance like the RAP along the leading edge of the
moisture gradient. Unfortunately beyond this the meso models
aren`t making things much clearer with mixed signals regarding
convection coverage and placement. This is one where the mesoscale
details will play a key role, and this will require careful
assessment through the night. It`s worth noting that even one
lightning strike could be quite problematic in the wrong place
given the very dry fuels out there.
So we`ll stay the course with this forecast keeping a slight
chance for thunderstorms overnight and into Monday. We did make a
few adjustments this evening to increase PoPs a little for inland
portions of the Central Coast and to better refine
timing/placement of showers and thunderstorms into Monday based
on a consensus of the high resolution models. It`s worth noting
that some model solutions keep precipitation chances going into
Tuesday so this may need a closer look with the overnight forecast
update.
&&
.PREV DISCUSSION...as of 02:47 PM PDT Sunday...Local radar shows
scattered showers moving northward over the SF Bay area. While
much of this is virga, several enthusiastic reports have come in
via social media showing light rain or sprinkles. It doesn`t
appear to be measurable at this time. These sprinkles or light
showers may continue through the afternoon as upper level moisture
continues to advect into the region from the southeast.
Otherwise, a broken deck of high clouds appears on visible
satellite imagery, and lightning detection networks are flashing
over the southern Sierra and the interior deserts of SoCal into
southern NV.
Water vapor imagery shows a mid/upper low spinning a few hundred
miles off of the NorCal coast, while a ridge of high pressure
remains over the SW Conus. These features will help funnel
moisture up through CA over the next two days. PWATs will continue
to increase through tonight with models showing amounts reaching
up to 1.6"-1.8". Instability parameters will also be on the rise,
with steep mid-level lapse rates already in place. This, along
with abundant moisture and a pulse of energy riding around the
upper ridge may combine to set off high-based showers and/or
t-storms. Despite the moisture in place, lightning brings the risk
of fire starts and fire spread. Areas that have not been
influenced by the marine layer in recent weeks (above ~2500 ft
and the interior valleys) carry very dry fuels which could easily
ignite. While overall lightning risk is low, potential dangers are
high, as we`ve witnessed with current and recent wildfires in the
Sierra, interior valleys, and far northern CA. As the forecast
will likely change, please stay tuned for any updates.
Showers and slight thunderstorm risk will continue through Monday
into possible Monday evening in northern parts of the CWA, before
instability diminishes. Will continue to see some monsoonal
moisture Tuesday, along with moisture potentially from Hurricane
Frank`s remnants but storms appear unlikely at this time.
Temperatures will be pretty seasonable. Drier conditions and
warmer temperatures are likely Wednesday and Thursday, as the low
pressure center off the coast moves farther out to sea and ridging
takes hold. Temperatures then moderate by the end of the week into
the weekend.
&&
.AVIATION...as of 05:45 PM Sunday...For the 00Z TAFs. VFR into
the evening with some SCT-BKN cloud decks hanging around 15-20 kft
expected to persist throughout much of the TAF period as
monsoonal moisture continues to move through the area. Current
radar showing some elevated showers north of KAPC, though likely
not much making it to the ground at this point. Focus will shift
towards showers currently moving into the southern portions of our
area, expected to impact southern terminals by 07Z and Bay Area
terminals after 10Z. Kept TS out of the TAFs for now with
widespread lightning not expected near terminals, though the
chance of a few strikes is non-zero through Monday morning. MVFR
cigs likely overnight with IFR-LIFR locally in the early morning
hours for Monterey Bay terminals.
Vicinity of KSFO...VFR will last into the evening with MVFR cigs
expected before midnight through about 16Z Monday morning.
Overnight tonight, expect scattered showers after midnight with
the possibility for more widespread coverage during the early
morning hours Monday between 12-14Z. As mentioned previously,
widespread lightning activity is not expected near terminals, but
a few strikes cannot be completely ruled out. After clearing
Monday morning, expect VFR through the day with some lingering
high clouds at 15-20 kft.
KSFO Bridge Approach...Similar to KSFO.
Monterey Bay...MVFR cigs to return this evening around the
Monterey Bay with IFR/LIFR cigs expected after midnight. Scattered
showers are expected within a window of about 07-12Z before moving
northward out of the area. As mentioned previously,widespread lightning
activity is not expected near terminals, but a few strikes cannot be
completely ruled out. Clearing around 15-16Z will give way to mostly
clear skies with some lingering high clouds between 15-20 kft.
&&
.MARINE...as of 02:09 PM PDT Sunday...A fresh southerly swell at
approximately 15 to 17 seconds has arrived and will persist
through the upcoming week. Northwest winds are expected to be
generally light but breezier near coastal jets. Overnight tonight
into Monday morning features a slight chance for thunderstorms.
These storms may contain small hail, sporadic heavier rains as
well as locally erratic winds. Winds will stay light to breezy
through midweek when stronger northerly winds return by the end of
the week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...SCA...SF Bay until 9 PM
&&
$$
PUBLIC FORECAST: Lorber/SPM
AVIATION: Behringer
MARINE: McCorkle
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...Updated Aviation Forecast Discussion...
.DISCUSSION...
Issued at 302 PM CDT Sun Jul 31 2022
.Forecast Summary:
Isolated, strong to severe storms are possible late this
afternoon into evening, and again on Monday afternoon/evening. Hot
on Tuesday with potentially dangerous heat indices. Better shower
and storm chances on Wednesday.
.Late this afternoon through tonight:
Considerable boundary-layer moistening has occurred so far today
beneath steepening mid-level lapse rates from the west (see the
12z North Platte sounding). The result is a moderate to strongly
unstable, but capped air mass. A fairly well-defined midlevel
vorticity maximum is currently moving through the ND-MN Red River
Valley with a surface cold front just beginning to move into
northeast NE as of 2 PM. The primary question is whether the
glancing influence of the midlevel wave and low-level
convergence/uplift along the front will be sufficient to initiate
and sustain thunderstorms later today. The HRRR has consistently
suggested that the air mass will remain capped through this
evening with the NAMNest, Fv3, and NSSL-WRF all indicating
isolated storm development along the southward-advancing cold
front. Should storms develop, forecast soundings valid late this
afternoon into early evening depict an environment supportive of
organized multicell or supercell storm modes. As such, there is a
conditional risk for large hail (up to ping-pong ball size) and/or
wind gusts of 55-65 mph.
There is some indication that a belt of midlevel warm
advection/frontogenesis could yield a band of widely scattered
showers and storms over northeast NE late tonight, which could
linger into Monday morning.
.Monday and Monday night:
The above-mentioned surface front is expected to stall near the
NE-KS border before lifting north through the area on Monday. That
boundary in conjunction with the influence of another passing
midlevel disturbance may be sufficient to initiate a few storms
during the afternoon and evening hours. Again, the environment
would support organized storm modes with a conditional risk for
large hail and/or damaging wind gusts.
.Tuesday:
A shortwave trough tracking east along the north-central
U.S./Canadian border will induce strengthening, southwest winds
in the low levels, which in turn will advect a hot air mass into
the region from the southwest/west. The deterministic GFS and
GEFS remain considerably hotter than other model guidance, and
that`s influencing the NBM temperature forecasts to some extent.
The deterministic NBM maximum temperature forecasts for Tuesday
are in approximately the 80th percentile of the NBM ensemble with
highs of 101 at Omaha, 102 at Lincoln, 104 at Norfolk, and 106 to
109 degrees along the NE-SD border. It`s quite possible these
numbers are too high. However, the low-level wind pattern and
persistent, dry conditions argue in favor of temperatures toward
the tail of the distribution. Assuming these forecast highs are
close, associated heat indices of 104 to 108 are likely across
much of the area with values approaching 115 in the NE-SD border
region.
.Tuesday night into Wednesday night:
Phasing of the above-mentioned shortwave trough with a lower-
latitude disturbance moving out of WY and CO will result in a
corridor of midlevel height falls overspreading the mid-MO Valley
late Tuesday night into Wednesday. That forcing for ascent will
combine with a cold front moving south through the area to yield a
chance of thunderstorms from late Tuesday night into Wednesday
evening. Highs on Wednesday will be a function of cloud cover and
any ongoing showers and storms. For now, we will indicate
temperatures in the low to mid 90s. They could end up cooler than
that.
.Thursday into the weekend:
Mid/upper-level ridging is forecast to strengthen across the
region late this upcoming week with continued hot and dry
conditions.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 613 PM CDT Sun Jul 31 2022
Main concerns of the TAF period are outside chances for storms
around the KOMA terminal and chances for reduced ceilings/vis at
KLNK. As far as storm are concerned, any cloud development along
an incoming boundary has been stunted leaving dry conditions as
the most likely scenario. For KLNK ceilings/vis, the incoming
boundary should stall out and could have some low stratus south
of the terminal, but it looks to be too far south to affect the
terminal. Also of note, winds should shift back to the southeast
late tomorrow morning to early afternoon.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...Mead
AVIATION...Petersen
Area Forecast Discussion
National Weather Service Nashville TN
930 PM CDT Sun Jul 31 2022
...New UPDATE...
.UPDATE...
Issued at 930 PM CDT Sun Jul 31 2022
Best coverage of isolated to scattered showers and thunderstorms
continues across Upper Cumberland Region with isolated to
scattered showers across southern locations. Blended CAMs
solution showing potential of isolated to scattered showers and
thunderstorms through nighttime hours across entire mid state
region as upper level troughing influences slightly deepen and
an upper level disturbances at least approaches if not moves
across western portions of our area by late overnight hours.
Tweaked current hourly temperature, dewpoint, and wind speed/
direction grids blending them with associated previously
forecasted hourly gridded late evening values. Current temperature
trends continue to be in line with forecasted lows. Remainder of
forecast continues to be on track.
&&
.SHORT TERM...
(This afternoon through Monday Night)
Issued at 102 PM CDT Sun Jul 31 2022
A weak surface boundary remains situated in the vicinity of Middle
Tennessee and is helping to focus a band of moisture along which
scattered showers have been propagating for most of the day. The
HRRR suggests that heavier echoes will develop later in the
afternoon as a shortwave swings across the mid state, but a
significant portion of the region looks to remain rain-free
overnight with perhaps some redevelopment toward morning. At this
time, the potential for even localized flooding appears to be
greatly reduced for all but the southwest corner of Middle
Tennessee, which experienced significant rainfall amounts
yesterday afternoon. Expect the atmosphere to dry out considerably
by Monday afternoon as the aforementioned boundary slips to our
south and takes the bulk of the moisture with it.
&&
.LONG TERM...
(Tuesday through next Sunday)
Issued at 102 PM CDT Sun Jul 31 2022
A more summer-like air mass will settle in starting on Tuesday.
This will give us afternoon temperatures in the low to mid 90`s
for a couple of days, along with heat indices topping out at 100+
and enough residual moisture for isolated/scattered afternoon
convection each day. However, additional cloud cover beginning on
Thursday will help moderate temperatures (but certainly not the
humidity) into next weekend. So while we transition back to more
familiar summertime temperatures, it appears that we should be
able to avoid any prolonged dry spells for the foreseeable future.
&&
.AVIATION...
(00Z TAFS)
Issued at 627 PM CDT Sun Jul 31 2022
Isolated to scattered showers with very isolated thunderstorms will
move across the area through this taf cycle. Cigs through the
forecast will bounce between VFR and MVFR. CSV will have a span of
IFR cigs after midnight. Winds will be out of the SSW/SW around 5
kts through the overnight hours before increasing to near 10 kts
during the morning hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 73 88 73 93 / 40 50 10 30
Clarksville 72 90 72 94 / 40 40 10 20
Crossville 69 80 68 84 / 60 70 20 40
Columbia 72 87 71 92 / 40 60 10 30
Cookeville 70 83 70 87 / 60 70 10 40
Jamestown 69 81 68 85 / 60 70 20 40
Lawrenceburg 72 85 71 91 / 60 60 10 30
Murfreesboro 72 87 71 92 / 50 60 10 30
Waverly 72 90 72 94 / 50 60 10 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......JB Wright
SHORT TERM...Rose
LONG TERM....Rose
AVIATION.....13
Area Forecast Discussion
National Weather Service Paducah KY
639 PM CDT Sun Jul 31 2022
.UPDATE...
Issued at 638 PM CDT Sun Jul 31 2022
Updated the aviation section for the 00Z TAF issuance.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 246 PM CDT Sun Jul 31 2022
Precipitation has greatly underperformed as to what was expected
today as the weak boundary just to our south fizzled out as it
moved north. Models now indicate scattered showers and an isolated
thunderstorm at best until 03z across mainly west Kentucky, with
isolated convection to the west and north. The HRRR and RAP both
show an uptick in activity toward midnight and overnight across
mainly west Kentucky due to warm air advection and weak ripples in
the upper flow. Any convection across our south will die off by
midday Monday.
By Monday afternoon into Monday night, models show an upper level
wave moving through the Ohio valley. Chances of showers and some
thunderstorms will develop in our northeastern counties Monday
afternoon, then across our eastern half of counties Monday night,
especially during the evening hours. With better instability than
today, chances of seeing some thunderstorms will increase, and
SPC has our area in a Marginal risk.
Dry conditions are expected Tuesday morning. With the upper trof
just to our east and moist unstable air already in place, some
afternoon showers and storms will again be possible across mainly
our east half of counties.
High temperatures Monday will reach the lower 90s west to around
90 degrees east. With dew points in the middle 70s, heat indices
will reach the 100 to 105 degree range across southeast Missouri,
much of southern Illinois, and far west Kentucky. On Tuesday,
with more sunshine and continued southerly flow, highs will mostly
be in the lower 90s. This will push heat indices again into the
100 to 105 degree range across the entire PAH forecast area. Low
temperatures tonight through Tuesday night will be in the 70 to 75
degree range.
.LONG TERM...(Wednesday through Sunday)
Issued at 246 PM CDT Sun Jul 31 2022
The models are backing off slightly on the heat and humidity later this
week. Although the model 500 mb forecasts have not changed, there is
now a pretty strong signal that a surface boundary will move south
across the lower Ohio Valley late in the week. This boundary will
likely bring enough clouds and precip to impact temps, especially Thurs
and Fri.
The 500 mb pattern will consist of two strong highs, one over the
Plains and one near the Southeast US Atlantic coast. A weakness in the
ridge will exist over the Ohio Valley, becoming more pronounced
southward toward the Gulf coast. This weakness will apparently be
enough to allow a weak surface front to drift south across our region.
Precip chances will develop Wed night and especially Thursday, when the
front should be approaching the Interstate 64 corridor. Highs Thursday
are now forecast to be in the mid to upper 80s. Depending on the
arrival of pre-frontal clouds and convection, heat indices Thursday
should be a little lower than Wednesday.
The front or its remnants should provide more clouds and precip chances
on Friday. Highs are again forecast to remain below 90, though dew
points will remain in the 70s.
The models still indicate the 500 mb high will strengthen and relocate
over the mid Mississippi Valley Saturday and Sunday. This should result
in little if any rainfall, along with a buildup of heat and
humidity.
&&
.AVIATION...
Issued at 638 PM CDT Sun Jul 31 2022
Isolated drizzle is possible through the early evening hours. MVFR
cigs are likely at most sites through the night with MVFR vsby
possible with evening drizzle or late night fog, though cloud
cover will limit fog potential. There is a slight chance of light
rain late in the overnight period but low enough that it is left
out for now. Scattered showers/storms develop towards the end of
the TAF period near KEVV/KOWB and cannot be completely ruled out
further southwest. Winds will become light overnight, increasing
to 10 kts from the southwest with gusts of 15-18 kts during the
day.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...ATL
SHORT TERM...RST
LONG TERM...MY
AVIATION...ATL
Area Forecast Discussion
National Weather Service San Diego CA
843 PM PDT Sun Jul 31 2022
.SYNOPSIS...
Monsoonal moisture across the region will fuel shower and
thunderstorm development again on Monday with isolated showers
possible overnight. Local flash flooding will be possible near
the heavier thunderstorms again on Monday afternoon. The
atmosphere will dry out a bit, and become more stable through mid
week as high pressure builds aloft. This will be accompanied by
slight warming, but monsoonal flow is likely to return late in the
week as high pressure drifts east, and opens the door for more
clouds, showers, and thunderstorms across the region.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Update:
It was another active day of monsoonal thunderstorm activity
across especially the San Bernardinos and high desert region. See
local storm reports headlined on our webpage weather.gov/sandiego
for details on impacts today.
The activity has dissipated with just a few showers over the high
desert currently. A few showers could develop over Orange County
to the Inland Empire tonight. One lone shower had developed near
Perris but has dissipated. HRRR shows a few more showers
developing in this region overnight, but light rainfall amounts.
Another active monsoon day is forecast for Monday. See details
below from the previous discussion.
Previous Discussion:
Showers and thunderstorms were ongoing at 2 PM PDT, mainly over the
mountains and high deserts, although we have had a few showers over
Orange County as well. Please see the rainfall summary posted on our
webpage for the latest amounts we have been able to record. Very
heavy rainfall rates are possible, due to the high PW levels up to
two inches or more in some eastern portions of the forecast area. A
Flood Watch remains in effect for our northern mountains and high
deserts through 10 PM this evening.
Several more rounds of thunderstorms are possible over the mountains
and deserts this afternoon, and we could even see some scattered,
less intense shower/t-storm activity overnight into Monday morning,
even west of the mountains. Any marine layer clouds will likely be
patchy, if they develop at all tonight.
For Monday, not a whole lot of change is forecast as the monsoonal
flow continues, although some modest drying is indicated, and subtle
differences in the synoptic features aloft could affect how
widespread development is. The latest NAM12 has a weak easterly wave
moving north along the San Diego County coast late in the day. The
flow aloft from the S-SE could be a bit stronger as well, which
could decrease the flash flood potential a bit. All things
considered, there remains a significant flash flood threat on Monday.
Further stabilization of the atmosphere occurs after Monday though,
as the subtropical ridge strengthens along 35N. This position cuts
off the moist SE flow aloft into SoCal as well, further reducing any
shwr/tstm threat.
By Thursday, the ridge is on the move again, drifting NE and
settling over Colorado. The ridge also morphs back to a more
cellular form, guiding monsoonal moisture back up over SoCal,
renewing the chance for shwrs/tstms and increasing the humidity
levels. There is a wider spread of the ensemble solutions regarding
precipitation over SoCal with this next round, but a majority do
show some precipitation centered around next weekend and into early
the following week. Seasonal onshore flow is maintained as well, so
a shallow marine layer will likely persist, but could be disrupted
at times due to periods of convection. Daytime temperatures overall
should be near, or a bit below the seasonal average.
&&
.AVIATION...
010300Z...Coast/Valleys...SCT-BKN high clouds at/above 10,000 feet
MSL will continue through Monday morning. Patchy low clouds may
return to coastal areas after 10Z Monday. Most likely timing for
ceilings at coastal terminals is 11-15Z. Scatter out expected 15-
17Z. Very slight chances for SHRA and TSRA can be anticipated again
Monday afternoon, with a 20% chance of occurrence over the eastern
valleys and portions of the Inland Empire. Minimal precipitation
chances along/near the coast.
Mountains/Deserts...SCT-BKN high clouds at/above 10,000 feet MSL
through Monday morning. Scattered TSRA forming again over the
mountain and desert foothills generally after 18z Monday with most
activity diminishing by 03z Tue. Low confidence in any TSRA
impacting the terminals with PSP having the highest odds, albeit at
only a 20-30% chance. Downpours reducing VIS as well as gusty and
erratic winds will be possible with any TSRA.
&&
.MARINE...
An increasing southerly swell, up to 5 feet, from 180-200 degrees
and with a period of 12-14 seconds, is expected tonight through
Wednesday due to the remnants of Hurricane Frank.
&&
.BEACHES...
Hurricane Frank will generate hazardous surf conditions, including
strong rip currents, tonight through Wednesday. The 6 foot south
swell from 180-200 degrees at a period of 12-14 seconds will
generate surf of 4-7 feet, mainly along south-facing beaches.
Highest surf will be in northern Orange County.
&&
.SKYWARN...
Skywarn activation is requested for this afternoon, and may be
needed again on Monday.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Wednesday afternoon for Orange
County Coastal Areas-San Diego County Coastal Areas.
PZ...NONE.
&&
$$
PUBLIC...Gregoria (Update)/10 (Previous Discussion)
AVIATION/MARINE...Adams