Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/07/24
Area Forecast Discussion
National Weather Service Indianapolis IN
912 PM EDT Fri Sep 6 2024
.KEY MESSAGES...
- Becoming clear and cooler tonight, sunny and cool on Saturday
- Potential for sub-40 degree temperatures in rural areas Saturday
night, mainly north of I-70
&&
.FORECAST UPDATE...
Issued at 912 PM EDT Fri Sep 6 2024
Subsidence in the wake of a cold front along, a drying column per H-
Res soundings, dew points in the middle 40s to lower 50s advecting
in from the north all support clearing skies overnight. IR satellite
and surface obs were already showing clear skies north of a Terre
Haute to Noblesville line. Although, winds will stay up tonight
preventing ideal radiation cooling, cold advection will be at play
and should allow chilly temperatures to bottom out in the middle 40s
to the lower 50s or 10 plus degrees below normal.
&&
.SHORT TERM (This evening through Saturday)...
Issued at 244 PM EDT Fri Sep 6 2024
Synopsis:
Surface analysis this morning shows a cold front stretching from
Columbus OH, to south of Columbus IN and then southwest to western
KY. A few light rain showers were found in the wake of the front
over central Indiana. Precipitation was very isolated in coverage.
Winds in the wake of the front were front the north, ushering cooler
and less humid air into Central Indiana. Aloft, a large ridge of
high pressure was found across the western CONUS, while a deep upper
low was found over Ontario with a trough axis pivoting across the
Great Lakes and IL/IN/OH. GOES16 shows an area of cloud cover in the
wake of the front across central Indiana drifting southeast, while
the rest of the state was essentially partly cloudy.
Late this afternoon and Tonight -
Clouds associated with the departing cold front will slowly progress
south and east across Central Indiana this afternoon and early
evening. South of these clouds, temperatures reaching the lower 80s
appear warm enough to generate a few showers and thunderstorms late
this afternoon. HRRR continues to suggest isolated to scattered
shower or storm development late this afternoon across points south
and east of Indianapolis. Forecast soundings and ACARS suggest some
limited but available CAPE this afternoon ahead of the front. Thus
as we reach peak heating hours, a few isolated showers and storms
across the SE parts of the forecast area cannot be ruled out.
By 00Z-02Z HRRR suggests any precipitation will have drifted east
and exited the forecast area. Clouds upstream of this cloud band
appear quite diurnal in nature. This will suggest a quick
deterioration of cloud cover this evening. Forecast soundings trend
toward a dry column overnight as subsidence is expected to build.
Thus will trend sky cover overnight toward mostly clear skies. A
moderate pressure gradient in place should allow for a sustained
winds of 5-10 mph overnight, prevent full radiational cooling. Lows
tonight should fall to the upper 40s and lower 50s.
Saturday -
The upper low will is expected to be over eastern Ontario on
Saturday while strong ridging remains in place over the Rockies.
This will result in strong NW flow across Indiana along with strong
subsidence. Mid levels show strong drying through the day spreading
from the NW across Central Indiana. Forecast soundings and time
heights also show a very dry column. Thus a mostly sunny day will be
expected as surface high pressure builds across the area from the
north. Strong cold air advection will be in play, allowing 850mb
temps to fall to 4C by 12Z Sat. This will allow highs in Saturday to
only reach the upper 60s to near 70 which will be a true taste of
fall temperatures.
&&
.LONG TERM (Saturday night through Friday)...
Issued at 244 PM EDT Fri Sep 6 2024
Expect quiet weather conditions through the long term period as
surface high pressure remains dominant across the Ohio Valley. The
main focus in the extended will be anomalously cold overnight lows
this weekend and worsening drought conditions into next week.
Upper troughing will persist through the weekend helping to keep
temperatures below normal. Widespread lows in the low-mid 40s are
likely Saturday night as surface high pressure continues to build in
providing optimal radiational cooling conditions. Given the good
setup for radiational cooling and the very dry airmass in place,
temperatures usually end up on the lowest end of model guidance.
This may allow for rural areas across the north to fall into the
upper 30s. Frost is unlikely, but there could be a few highly
localized areas that drop into the mid 30s which could damage highly
sensitive vegetation.
The aforementioned upper trough should begin to shift east by early
next week with upper ridging building in. At the surface, high
pressure will continue to remain dominant which will allow dry
weather to continue. This extended dry stretch will likely lead to
worsening drought conditions and an expansion in drought coverage.
There is a weak signal for low rain chances late next weekend into
the following week, but beneficial precipitation looks unlikely in
the next 7-10 days. Expect temperatures to quickly warm up as the
upper ridge builds across the region. Widespread highs in the mid-
upper 80s are likely by the middle of next week.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 621 PM EDT Fri Sep 6 2024
Impacts:
- None
Discussion:
Would not rule out a brief shower this evening as an upper trough
pivots across the Great Lakes. A strengthening low pressure gradient
will result in breezy northwest winds with gusts to 20+ plus mph
this evening. More gusts to 20 knots or more are expected Saturday
as the atmosphere mixes down. Otherwise, look for VFR conditions
with some lingering evening stratocu and possibly scattered fair
weather diurnal cu Saturday afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...MK
SHORT TERM...Puma
LONG TERM...Melo
AVIATION...MK
Area Forecast Discussion
National Weather Service Marquette MI
721 PM EDT Fri Sep 6 2024
.KEY MESSAGES...
- High swim risk through Saturday for the Lake Superior beaches
of Marquette and Alger counties.
- Light lake effect rainfall continues through at least Saturday
morning.
- Drier and warmer weather returns next week with increasing
ridging from the west.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 228 PM EDT Fri Sep 6 2024
Water vapor imagery shows a midlevel trough extending from near
Hudson Bay to the Great Lakes, with a surface low moving into Quebec
per RAP analyses. As a result, the UP remains under chilly northerly
flow with 850mb temperatures already analyzed at around 3-4C. With
Lake Superior surface temperatures at around 11-18C, delta-Ts are
high enough to keep the lake effect machine going. Most of the UP
remains under a blanket of low lake clouds, with light lake effect
rain showers/drizzle continuing mainly across the central and
eastern UP. Temperatures, meanwhile, are climbing into the low to
mid 50s across most of the UP so far, and may be able to peak closer
to 60F in Menominee county. However, some spots closer to Superior
are struggling to get out of the 40s. Under cloudy skies,
temperatures shouldn`t budge much more the rest of the afternoon.
Winds mainly out of the north remain gusty, particularly across the
eastern UP, with gusts up to 20-25mph common.
Tonight, 850mb temperatures continue to fall back to around 0-2C.
This will support lingering lake effect clouds/showers across the
eastern half of the UP, while cloud cover slowly erodes to the west
as flow turns more anticyclonic. The main forecast concern for
tonight remains the potential for frost. Our chilly airmass would
support widespread overnight lows in the 30s, with the lower/mid 40s
more common closer to the lakeshores. Where skies can clear, and
particularly in the typically cooler spots in the interior-western
UP, temperatures may fall into the mid 30s, with a slight chance
(20%) for even cooler values closer to the freezing point. If cloud
cover persists, however, temperatures even out west may come in
slightly warmer and limit our frost potential. Therefore, will
continue to shy away from any headlines.
&&
.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 339 PM EDT Fri Sep 6 2024
Starting on Saturday, the mid level troughing over the Great Lakes
gradually shifts east developing into a closed low. At the same
time, the UP will be straddled between a deepening sfc low to the
east and high pressure to the west. This continues the cold
northerly flow setup over the region. Lake Superior temps are
currently around 15-19C and with 850 mb temps starting the day
between 2C to -2C (colder east), delta-Ts will still be supportive
for lake effect showers. As a warmer and drier airmass works its way
in, these gradually diminish. Colder than normal temps are expected
under the cool north flow, ares in the north-central and northeast
will only peak in the mid 50s underneath partly cloudy skies that
linger for much of the day. Where lake effect cloud cover scatters
out earlier, warmer temps peak near 60. The UP turns dry Saturday
night as lows settle into the upper 30s to upper 40s, warmer near
Lake Superior. Although cool conditions are not ideal for a beach
day, high swim risk for dangerous rip currents continues at
Marquette County beaches through Saturday afternoon and sunset at
Alger County Beaches thanks to persistent north winds.
While mostly dry weather is likely to persist on Sunday, very low
chances (15-20%) for light showers accompany a weak sfc trough
settling southeast into the Upper Great Lakes. It has support from
the left exit region of an upper level jet, cyclonic flow, and weak
isentropic ascent. The limited forcing and spotty moisture noted in
the model soundings leave low confidence in precip during this
period. That said, partly cloudy skies likely accompany this
disturbance Saturday night into Sunday. Otherwise, highs on Sunday
warm near normal in the upper 60s to mid 70s, cooler in the east.
Lows Sunday night are expected in the mid 40s to mid 50s.
Next week, remains mainly dry as mid level ridging shifts east from
south central Canada/Northern Plains to the Great Lakes. This sets
up a blocking sfc high over the east to eventually northeast CONUS
that prevents much of any precip from making it into our area. While
there is a very low chance ~15% for showers accompanying a shortwave
Tuesday night/Wednesday, the better forcing looks to remain to the
north of our CWA. Also, ensemble probabilities of at least 0.01" are
only around 20%, so chances for accumulations are low. Thus, kept
forecast dry for now; will see partly cloudy skies Tuesday night
through Wednesday. The mid level ridging along with the advance of a
850 mb thermal ridge with temps approaching 17-19C by midweek means
above normal temps will return to Upper MI. Chances for high temps
mid to late next week pushing into the 80s are increasingly likely
with lows in the 50s. Although confidence in timing is still low due
to model spread, our next best chances for measurable precip likely
holds off until late next weekend as a low well to the north drags a
cold front through our area.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 720 PM EDT Fri Sep 6 2024
Lingering MVFR conditions will persist at KSAW overnight with
predominately northerly, upslope flow. Lake effect rain/drizzle
should be expected off and on at least until into the morning
hours, when dry air should help end shower activity. At KCMX and
KIWD, scattered lake induced cloud cover is expected to persist
tonight. Conditions should primarily be VFR, but some tempo
MVFR ceilings can`t be ruled out.
&&
.MARINE...
Issued at 339 PM EDT Fri Sep 6 2024
North winds continue into Saturday morning as Lake Superior sits
between high pressure descending into the Upper Mississippi River
Valley and a deepening low pressure system moving north into Quebec.
Gusts up to 20-25 kts are expected over the west half of the lake
with gusts up to 30 kts over the east half through early tonight.
Late tonight through Saturday, gusts over the west hold 20 kts or
less with gusts up to 20-25 kts over the east. As the high pressure
flattens out over the Mid Mississippi River and Ohio River Valleys,
winds back west Saturday into Saturday night, gradually diminishing
to around 20 kts or less Saturday night. West winds increase late
Saturday night/Sunday morning to 20-25 kts, strongest over the west
half of the lake. Winds fall back below 20 kts Sunday evening. South
winds return late in the day Monday, remaining less than 20 kts
across the lake through the rest of the forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 9 PM EDT this evening for MIZ005-
006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...LC
LONG TERM...Jablonski
AVIATION...JTP
MARINE...Jablonski
Area Forecast Discussion
National Weather Service Phoenix AZ
450 PM MST Fri Sep 6 2024
.UPDATE...Updated 00z Aviation Discussion.
&&
.SYNOPSIS...
Unseasonably strong high pressure over the region will continue
to support excessively hot temperatures with highs exceeding 110
degrees for most lower desert locations this afternoon. Some
modest relief from the heat is expected starting this weekend as
temperatures retreat to around 4 to 6 degrees above normal.
Breezy easterly winds during the morning hours are expected each
day through this weekend across much of the area. A slight
moisture increase for today and Saturday should also bring some
very isolated showers and maybe a few storms over higher terrain
areas before conditions dry out again heading into next week.
&&
.DISCUSSION...
Today started off on a warm note, especially in South-Central AZ
where breezy easterly gradient winds this morning inhibited
radiational surface cooling. Phoenix set a new record warm low
for both the day and the month of September with 93F. Much of
South-Central AZ lower deserts only fell into the upper-80s to
lower-90s this morning. Despite the warm start, midday
temperatures 3-6 degrees cooler than yesterday`s midday readings,
and this applies to most of the region. So, it is not expected to
get quite as hot this afternoon as it did yesterday. Still,
forecast highs are around 107-114F across the lower deserts,
leading to widespread Major HeatRisk. Heading into this weekend,
high pressure is expected to remain situated over the region, but
weaken slightly, with models showing H5 heights falling from the
594-595dm they are at now to 589-591dm by the end of the day
Saturday. This weakening of the high will allow for afternoon
temperatures to moderate/cool another 2-4 degrees this weekend,
dropping most lower desert locations into the Moderate HeatRisk
category. There will still be isolated areas of Major HeatRisk,
based on the latest forecast, out in the western lower deserts. As
a result the Excessive Heat Warning has been extended through
this weekend for areas along the Colorado River, including the
City of Yuma. Otherwise, the warning will expire elsewhere this
evening.
There was a push of low level moisture into the region overnight,
with mesoanalysis showing PWATs around 1.0-1.2". This moisture
increase will support showers and storms the next few days. This
afternoon, HREF has the best chances mainly along the White Mtns
and Rim. The HRRR has been consistently supporting isolated
convection in Southern Maricopa County, in the Tabletop Mesa area,
but it is an outlier compared to the other HREF members. The HRRR
continues to be somewhat of an outlier for Saturday as well,
particularly with the intensity and coverage of convection. On
Saturday, and Sunday, shower and storm chances do at least expand
to the western deserts. Afternoon convective development the next
few days will favor typical high terrain areas and features and
likely will struggle to survive once descending off the high
terrain. Areas most favorable or convection across Southern AZ and
SoCal this weekend will be the Kofas area up through La Paz
County and the higher terrain of Riverside County CA, including
Joshua Tree NP. Any shower or storm the next few days will be
capable of producing strong winds (>35 mph). With high cloud
bases and the T-Td spreads, DCAPE will be quite high (1700-2100
J/kg). Overall, rainfall will likely remain limited given the dry
sub-cloud layer and limited instability, but any storms anchoring
to a terrain feature, like in western Joshua Tree NP, could lead
to minor flood impacts.
Heading into next week drier air is expected to continue to shift
into the region, ending any rain chances across southeast
California and southern Arizona. The high pressure ridge will also
begin to weaken again early next week with H5 heights lowering by
mid week as a large trough gradually shifts southeastward across
the Western U.S. Forecast temperatures still hover roughly 5
degrees above normal through Tuesday, but the trough should
eventually drop highs to below 105 degrees by around next
Thursday. The trough is also expected to turn flow out of the
southwest from around Wednesday through at least late next week
and this will keep dry air in place with surface dew points mostly
in the 30s to lower 40s. Long range guidance still tries to show
an increase in moisture by around next weekend, but the likely
lingering influence of the trough may be enough to keep any deeper
moisture from reaching the Desert Southwest.
&&
.AVIATION...Updated at 2350Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation concerns are expected during the TAF period
under FEW mid level clouds mainly aoa 11 kft. Winds will
predominantly be out of the E/SE through the period, though some
light speeds, periods of variability, and potentially a brief west
switch (aob 5 kt sustained) will be possible through around 04Z
this evening. Isolated convective activity developed across high
terrain areas to the north and east of the Phoenix metro this
afternoon, and further isolated development over parts of SW AZ
cannot be ruled out as we head into the early evening, but chances
for TAF sites are too low to warrant any mention of VCSH/VCTS. The
main impact of any of this distant convection for the remainder of
today will be the potential for outflow winds to reach the
terminals, most likely from the NE/E, later in the evening. E/SE
winds will prevail after 04-05Z this evening and are expected to
gust to around 20 kts Saturday morning. Tomorrow afternoon and
evening, distant mountain thunderstorm activity is once again
anticipated over the high terrain of South-Central AZ and parts of
SW AZ. Hi-Res guidance is in fair agreement that the main impact
of any thunderstorm activity tomorrow will once again be gusty
outflow winds, most likely out of the NE, reaching the terminals
as early as 00-01Z in the late afternoon.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected through at least midday tomorrow
under FEW mid level clouds. Winds at KIPL will be prevail out of
the SE through the TAF period, with speeds mainly aob 10 kt
sustained. At KBLH, diurnal trends will prevail, with periods of
variability Saturday morning. Isolated thunderstorms are expected
to develop over prominent terrain features of SW AZ and SE CA
tomorrow afternoon. Though the chances of storms directly
impacting either of the terminals are too low to mention in the
TAF (5% or less at KIPL and less than 15% at KBLH), abrupt wind
shifts from any thunderstorm outflows will become a concern at
both terminals.
&&
.FIRE WEATHER...
Hot, overall dry conditions, and breezy easterly winds are
expected through Sunday. A slight increase in moisture today into
Saturday may bring some isolated higher terrain showers and maybe
a thunderstorm or two, but chances are fairly low and CWR are
less than 10%. Breezy easterly winds are expected to develop again
Saturday and Sunday morning across much of the area with gusts in
the eastern districts along ridgetops up to around 30 mph. These
easterly winds will diminish during the afternoons. Humidities
will improve for today and Saturday with afternoon MinRHs around
15% across the lower elevations to 25-30% over far eastern
districts. Conditions will then dry out again into next week as
temperatures remain at least a few degrees above normal each day.
&&
.CLIMATE...
Record highs:
Date Phoenix Yuma El Centro
---- ------- ---- ---------
Sep 6 113 in 2020 115 in 2020 118 in 2020
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ... Excessive Heat Warning until 8 PM MST this evening for AZZ531-
533>544-546-548>551-553>555-559.
Excessive Heat Warning from 8 PM this evening to 8 PM MST Sunday
for AZZ530-532.
CA... Excessive Heat Warning until 8 PM PDT this evening for
CAZ560>568-570.
Excessive Heat Warning from 8 PM this evening to 8 PM PDT Sunday
for CAZ569.
&&
$$
DISCUSSION...Benedict/Kuhlman
AVIATION...Whittock
FIRE WEATHER...Kuhlman
CLIMATE...18
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
845 PM EDT Fri Sep 6 2024
...New UPDATE, AVIATION...
.UPDATE...
Issued at 845 PM EDT Fri Sep 6 2024
Convection has moved into the interior as the west coast sea
breeze has drifted inland this evening, but the east coast sea
breeze has been moving quickly west and has overwhelmed the west
coast sea breeze. Scattered convection has developed along and
behind the east coast sea breeze and will continue through the
late evening hours. Majority of these showers and thunderstorms
should stay over the interior, but could see a few move back
closer to the coast around Tampa Bay and the Nature Coast over
the next few hours. For Saturday a more south to southwest flow
will setup so we could see some late morning and early afternoon
convection near the coast, but the majority of the showers and
thunderstorms will be over the interior during the mid to late
afternoon and evening hours. The exception will likely be
southwest Florida where the flow will start out more southeasterly
then become southwest later in the afternoon allowing convection
to develop closer to the coast. Overall the current forecast
looks good with no changes needed.
&&
.AVIATION...
(00Z TAFS)
Issued at 845 PM EDT Fri Sep 6 2024
Scattered convection will continue around LAL this evening,
otherwise rain-free VFR conditions are expected into early
morning Saturday. Some areas of MVFR ceilings will be possible
with daytime heating during the mid to late morning hours with
scattered convection developing in the early afternoon near the
coast then moving into the interior by evening causing some
MVFR/local IFR conditions. Light winds overnight will become south
at 5 to 10 knots during Saturday morning then shifting to
southwest to west during the afternoon.
&&
.DISCUSSION...
Issued at 207 PM EDT Fri Sep 6 2024
The synoptic pattern shows weak upper ridging and surface high
pressure sitting over the mid-Atlantic states. A surface low
continues to spin off the New England coastline in the northern
Atlantic. The associated frontal boundary extends southwest through
the western Atlantic, becoming stationary over northern Florida and
extending further westward through the northern Gulf of Mexico to
another surface low over the western Gulf of Mexico. Upper ridging
and surface high pressure continues to ridge west across central and
southwest Florida. Not a whole lot of change in this pattern is
expected through the period. Overall, high pressure remains north
over the mid-Atlantic states and over south Florida with the
stationary boundary remaining situated over northern and central
Florida through the forecast period. The biggest change will be a
slight shift in winds from a southwest through southeast flow to a
more easterly flow by the start of next week. With all that said, we
will remain predominately on the south side of that stationary
frontal boundary keeping west central and southwest Florida in a
warm and moist environment. PWAT values will remain quite high
ranging between 2.0 - 2.4 inches over the region. This will continue
to support scattered to numerous showers and storms each day.
The latest HRRR guidance for today has showers and storms developing
early afternoon along the west coast and SW Florida and traversing
inland during the late afternoon/evening on a SE through SW wind
flow. The highest rain chances will be over the interior counties
east of I-75. As we have seen over the past few days, some of these
storms could cause some localized flooding impacts over already
saturated soils. All of west central and southwest Florida remains
in a Marginal Risk of Excessive Rainfall for today with parts of
central and northern Florida remaining in a Marginal Risk of
Excessive Rainfall through the weekend. Daytime highs will top out
in the upper 80`s to low 90`s, with heat indices reaching 100-105
degrees each day.
&&
.MARINE...
Issued at 207 PM EDT Fri Sep 6 2024
Southeast through southwest winds around 10 knots and seas 2 feet or
less expected through the weekend, with a weak sea breeze possible
near the coast each afternoon. Winds become more easterly by the
beginning of next week and slightly increasing to around 10-15
knots. Daily showers and storms will be possible each day through
the weekend and into next week. No headlines are expected.
&&
.FIRE WEATHER...
Issued at 207 PM EDT Fri Sep 6 2024
A stationary frontal boundary remains stretched across northern
Florida with high pressure over south Florida. This pattern will
favor warm and humid weather through the weekend and into next week.
Scattered to numerous showers and storms can be expected each day
through the period. No fire weather concerns are expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 77 91 76 91 / 30 50 20 70
FMY 77 93 77 93 / 30 60 40 60
GIF 75 94 75 92 / 50 60 30 70
SRQ 77 91 76 92 / 20 30 30 60
BKV 73 92 73 91 / 30 50 20 70
SPG 80 91 80 91 / 20 40 30 60
&&
Sea Breeze Thunderstorm Regime For Saturday: 4
Sea Breeze Thunderstorm Regime For Sunday: 6
For additional information on sea breeze regimes, go to:
https://www.weather.gov/tbw/ThunderstormClimatology
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Close
DISCUSSION/MARINE/FIRE WEATHER...Wynn
DECISION SUPPORT/UPPER AIR/CLIMATE...Hurt/Ulevicius