Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/28/23
Area Forecast Discussion
National Weather Service Birmingham AL
731 PM CDT Wed Sep 27 2023
...New SHORT TERM, AVIATION...
.SHORT TERM...
(Tonight through Thursday)
Issued at 700 PM CDT WED SEP 27 2023
Surface high pressure will continue building southward down the
spine of the Appalachians into Thursday. Some low level moisture
will remain over the southern half of the area, but should start
to move southward with time. Do expect some clouds and possible
ceilings lasting into Thursday south. Rain chances appear minimal
at this time. The forecast remains on track and no big changes
planned.
75
Previous short-term discussion:
(This evening through Thursday)
Issued at 105 PM CDT WED SEP 27 2023
Cloud cover is thicker generally near and southeast of the
Interstate 59 corridor early this afternoon. RAP 13 km
mesoanalysis fields depict some weak moisture convergence in the
lower levels across the Southeast counties where chances for some
showers and a few storms will be greatest through the afternoon
and into the early evening hours. Elsewhere, an easterly flow
being propelled by strong surface high pressure across Southeast
Canada that is nosing southwest down the spine of the Appalachians
is providing more pleasant temperatures across portions of our
eastern counties at this writing. The mid levels aloft feature
longwave ridging over the Four Corners States northwest to over
the Northern Plains while a closed low was positioned over
Northern Illinois with broad troughing over much of the Ohio and
Tennessee Valley regions.
Tonight.
The closed low to our north will move east toward Lake Erie
overnight while the longwave broad troughing persists overhead.
Other than a few lingering showers generally southeast of the
Interstate 85 corridor, dry conditions are forecast across the
rest of the area with mostly cloudy skies southeast and fewer
clouds to the northwest. Winds will remain from the east with
speeds from 3-6 mph. Lows will range from the upper 50s far east
and northeast to the mid 60s across the southwest.
Thursday.
The closed low will continue to move east over the Eastern Great
Lakes on Thursday while mid-level ridging builds over the Southern
and Central Plains. Our area will remain beneath broad troughing
aloft while a few disturbances move southeast from over the
Central Plains into the Southern Ohio River Valley Region. Clouds
will remain the thickest across the far southeast portion of the
area where some isolated showers will remain possible due to
lingering weak surface convergence. A few more clouds may move
over the northwest counties later in the day as some disturbances
move over the Tennessee Valley Region but conditions will likely
remain dry across our area. Easterly winds will persist through
the day with speeds from 4-8 mph. High temperatures will range
from near 80 in the higher elevations far east to the upper 80s
far west and southwest.
05
&&
.LONG TERM...
(Thursday night through Tuesday)
Issued at 339 PM CDT WED SEP 27 2023
No major changes were made to the extended forecast. Continuing
with a trend of a rain free forecast for the latter part of this
week, into the weekend, and the beginning of next week. Continuing
with slightly lower than guidance on dew points and slightly
higher on highs with this persisting dry airmass. Fortunately,
winds are not expected to be high enough with no major systems to
call for fire weather issues.
08
Previous long-term discussion:
(Thursday night through Tuesday)
Issued at 145 AM CDT WED SEP 27 2023
A 591 decameter ridge will build from the Southern Plains to the
Ohio Valley during the extended period, downstream of a highly
amplified trough over the western CONUS. Meanwhile a trough over
the eastern CONUS will gradually move offshore, with a weaker
positive tilt trough extending into the northeast Gulf. At the
surface, high pressure over the eastern CONUS will maintain an
easterly component to surface winds across Central Alabama. There
is a low but non-zero (10%) chance for weakening showers and
storms associated with a shortwave in northwest flow aloft to make
it into our far northwest counties before dissipating Thursday
evening. There`s also a low but non-zero chance (5-10%) of a
stray shower in our far southeast counties over the weekend due
to a weak upper low along the Gulf Coast, but this feature is
trending weaker. Odds strongly favor a prolonged dry period for
Central Alabama. Easterly winds will be a limiting factor for high
temperatures especially in East Alabama, but with the mid-level
ridge trend further to the east and worsening drought conditions
will forecast highs on the higher side of guidance especially in
West Alabama.
32/Davis
&&
.AVIATION...
(00Z TAFS)
Issued at 700 PM CDT WED SEP 27 2023
Easterly flow will prevail through the period. The winds will
range from light overnight to 5-10kts on Thursday. The moisture
content remains the highest east and south and expect some MVFR
ceilings overnight. Mentioned at ANB/TOI/MGM to start off and will
monitor where these clouds end up. Otherwise, some VFR ceilings
mainly south.
75
&&
.FIRE WEATHER...
Scattered showers and isolated thunderstorms will be possible
this afternoon into Thursday across the southeastern portions of
Central Alabama. Otherwise, a prolonged dry period is expected.
Minimum relative humidity values generally remain above 40 to 45
percent this afternoon and Thursday, but generally drop into the
35 to 45 percent range Friday and through the weekend. 20 foot
winds will be out the east mainly less than 10 mph.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 60 83 59 86 / 0 10 0 0
Anniston 61 83 60 87 / 10 10 0 0
Birmingham 65 84 63 86 / 0 10 0 0
Tuscaloosa 66 88 63 89 / 0 10 0 0
Calera 64 84 63 88 / 10 10 0 0
Auburn 62 81 62 84 / 10 10 0 0
Montgomery 65 86 63 88 / 10 10 0 0
Troy 65 84 63 87 / 10 20 0 0
&&
.BMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...75
LONG TERM....08
AVIATION...75
Area Forecast Discussion
National Weather Service Grand Rapids MI
934 PM EDT Wed Sep 27 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 934 PM EDT Wed Sep 27 2023
Have increased PoPs substantially (to 80-100%) south and east of
GRR where showers continue to blossom related to a well-defined
spoke of vorticity pivoting n/nw around the upper low. Some
question as to how much farther north and west this rain area
makes it overnight as the upper low over nw Indiana tracks slowly
east-northeast, but for now will go with about GRR to MOP as the
westernmost edge of the more widespread rain. Thunder threat looks
too low to maintain a mention of in the fcst overnight given
current lack of any lightning activity and latest RAP MUCape progs
of less than 200 J/KG.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 216 PM EDT Wed Sep 27 2023
Pockets of positive vorticity advection and warm air advection
along with ample low level moisture will continue chances (20-30%)
for showers this afternoon. There isn`t much in the way of CAPE to
work with so the chances for thunderstorms are pretty low (20% or
less) and would remain south of the I-96 corridor. It is also
south of this corridor that we have the best chances (30-50%)
overnight. As the upper level low slowly tracks to the east we
move back into northwest flow, chances for showers diminish
through Thursday morning. We`ll still have some low level moisture
sticking around which will unfortunately result in lingering
clouds.
.LONG TERM...(Friday through Wednesday)
Issued at 216 PM EDT Wed Sep 27 2023
A ridge will build over the area Friday evening and strengthen as
the previous low sets up to the east and another cutoff low builds
over Nevada forming an omega blocking pattern. Warm air advection
in this ridge will bring above normal temperatures for this time
of year along with drier air to the area. Temperatures are expected
to be in the upper 70s to lower 80s over the weekend and into the
beginning of next week. The blocking pattern has the potential to
break down towards the end of the forecast period, which could
bring us chances of precipitation later next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 740 PM EDT Wed Sep 27 2023
An upper low over northern IL continues to influence our weather.
Radar shows showers moving northwestward across the region and
most of the terminals should see at least a little rain. There`s a
fairly decent signal for IFR overnight at the terminals. However
MKG may be the exception; we included a tempo toward sunrise for
that potential. After that a slow rise to MVFR by early afternoon.
&&
.MARINE...
Issued at 216 PM EDT Wed Sep 27 2023
Breezy easterly winds to 20 knots become lighter overnight and
turn more southerly by next week.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Meade
SHORT TERM...RAH
LONG TERM...Vernon/RAH
AVIATION...04
MARINE...RAH
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1045 PM CDT Wed Sep 27 2023
.SYNOPSIS...
Issued at 1013 PM CDT Wed Sep 27 2023
Temperatures will fall into the upper 50s to lower 60s tonight,
with increasing cloud cover and fog development expected after
midnight. Highs on Thursday will warm into the mid to upper 70s
under mostly sunny skies by afternoon. Dry weather and
temperatures in the 80s return to the forecast Friday through the
weekend.
&&
.UPDATE...
Issued at 808 PM CDT Wed Sep 27 2023
Isolated convection associated with an upper low swirling over
northeast Indiana is largely driven by diurnal instability, and
will fade from the far northeast CWA over the next couple hours.
Farther south, more robust convection has recently developed near
a stationary boundary along I-64 in southern IL where higher
instability is present. Recent CAM guidance suggests this activity
will remain south of the CWA this evening and have reduced PoPs
to slight chance south of a Flora to Lawrenceville line. The main
forecast issue overnight is the expected development of fog and
low stratus after midnight as dewpoint depressions approach zero
and winds remain calm. Increased cloud cover in grids and bumped
up fog mention to widespread. Currently have lower confidence on
how dense the fog will become, due to the expected presence of
thicker stratus layer above, but it`s possible a dense fog
advisory will be needed late tonight for the northern and central
CWA. Lows should fall into the upper 50s/lower 60s.
25
&&
.DISCUSSION...
Issued at 201 PM CDT Wed Sep 27 2023
This afternoon, water vapor imagery shows an upper low centered
over northeastern Illinois, while at the surface, a stationary
front is draped from southeastern Kansas across southern Illinois
and along the Ohio River Valley. These two features are the
primary forcing mechanisms for scattered showers and a few storms
this evening and overnight with the frontal boundary being the
primary area of concern in terms of any severe threat later today.
Latest RAP continues to indicate that around 1000 J/kg MLCAPE
will be in place near the frontal boundary which is currently just
south of the forecast area. Stable clouds are noted on visible
satellite imagery in the southern half of the forecast area and
north of the front. Barring any notable north shift in the frontal
boundary, the severe threat seems favored to stay just south of
the forecast area, but cannot rule out some slightly elevated
storms that are capable of producing large hail or damaging wind
gusts south of I-70.
Upper low will shift across Indiana and Ohio Thursday with
northwest flow overspreading central Illinois in its wake.
Building upper ridge and mid level height rises overspreading the
region will suppress precip changes, but steep low level lapse
rates may support sufficiently deep cumulus field to support a few
isolated sprinkles, especially east of I-57 Thursday afternoon.
Otherwise dry weather will be in place with afternoon highs in the
mid to upper 70s.
An upper ridge will build across central Illinois Thursday night,
then gradually amplify through the weekend as it generally stays
centered along the Mississippi River Valley. Dry conditions will
prevail under the upper ridge axis and temperatures will trend
back towards above normal which is highs in the mid 70s. Highs in
the low to mid 80s are expected Friday through the middle of next
week.
Deubelbeiss
&&
.AVIATION... (For the 06z TAFs through 06z Thursday Night)
Issued at 1045 PM CDT Wed Sep 27 2023
Current VFR conditions are forecast to rapidly deteriorate to
LIFR between 06-08z (likely after a brief period of MVFR), as low
stratus and fog develop. Short range guidance shows high
probabilities of LIFR to VLIFR ceilings and visibilities overnight
across all central IL terminals. Gradual improvement is expected
after sunrise, with VFR skies returning between 17-20z from the
southwest. Winds to be light northeast under 10 kt through the
forecast.
25
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service New Orleans LA
627 PM CDT Wed Sep 27 2023
...New AVIATION...
.SHORT TERM...
(This evening through Thursday night)
Issued at 242 PM CDT Wed Sep 27 2023
Starting out this evening with a brief synoptic overview, a weak
inverted trough remains situated over the northern Gulf aiding in
a steady compression in pressure gradients/attendant easterly
flow. This axis is on the cusp of deeper Gulf moisture of around
1.7-1.9" total PW to drier continental air pulling south from MS
for areas north of I-10/12 with PW`s in the 1.1-1.3" range. Slight
bit of a difference between these two areas stretched across the
CWA, with deeper PBL mixing allowing for lower dewpoints across
northern areas, reaching the low 60`s per recent obs and
noticeable low/mid-level compressional warming/subsidence keeping
a cap on things. However, will have to monitor coastal areas this
evening right on the fringe of increasing PW`s and slightly
greater lift to get some coastal t-storms for a few hours before
sunset. Perhaps organizing into small squalls bringing brief gusty
winds at times. Not entirely confident on the inward extent of
convection once we become more dominated into the continental
airmass per aforementioned reasonings, and did decide to bump
PoPs down some for inland areas, keeping PoPs more confined to SE
LA and coastal MS. Additionally, watching thicker clouds building
in from the east from a noticeable cold air damming situation
with distinctly cooler temperatures. Will watch how this modified
airmass builds in from the NE with time and how it could affect
temperatures across coastal areas tonight. Otherwise, conditions
get quiet later but will see a bit more convective coverage
increasing for marine areas tonight as marine instability takes
over, in conjunction with subtle lift from inverted trough.
Noticed HRRR trends trying to build in showers/storms along
squalls pulling into more inland locations of SE LA in the morning
hours, perhaps getting close to Houma to NOLA. Didn`t play with
PoPs much here keeping values highest over marine/immediate
coastal areas.
Not overly confident on the inland extent of coverage again
tomorrow, with the same noticeable moisture gradient stretched
E/W across half of the CWA. This brings the continued low/mid-
level suppression and lower PW airmass situated over the northern
areas, versus higher PW, Gulf airmass across coastal areas.
Decided to keep PoPs in place for coastal areas, but lowered some
10-15% or more for areas along/north of I-10/12 as yes, there
could be a passing shower but coverage should be limited in the
15-25% range. No modifications to temperatures as they seem on
track (but may need to closely watch drier areas, as today they
trended warmer than guidance), otherwise turning quiet Thursday
night going into Friday. Only other additional detail to the
earlier mention of increasing easterly flow will be occasionally
gusty winds along coastal areas, with adjacent marine headlines in
effect and may likely be extended into the day on Friday.
&&
.LONG TERM...
(Friday through Tuesday night)
Issued at 242 PM CDT Wed Sep 27 2023
The remainder of the forecast period from Friday onward looks start
off with continued daily rain chances, though the bulk of activity
will be south of I-10 in LA and marine areas. The upper low, which
will basically be an open trough by this point in the forecast, will
be digging across the southeast CONUS while swinging through the
Great Lakes/Ohio River Valley region. It should be reaching the
Atlantic coast by this weekend. At same time, upper ridge over the
Rockies early in the week will be following in the wake of the
trough and settling in over a wide area from the Great Lakes to the
northern Gulf coast. This upper level transition will increase
subsidence locally from north to south Friday into early next week.
Models continue to be in good agreement this general solution.
Therefore, have limited isolated/scattered POPs to around the I-
10/12 corridors with much higher coverage south of there.
Progressing into the weekend, should see a stead drying from north
to south with little activity not reaching much farther north than
the mouth of the Mississippi River. Temps continue to be at or
slightly above normal due to upper ridge nearby. Fall will come at
some point, just not there yet.
&&
.AVIATION...
(00Z TAFS)
Issued at 623 PM CDT Wed Sep 27 2023
VFR conditions will prevail through the period with generally
light winds overnight strengthening to around or just over 10
knots after sunrise Thursday. With low precipitable water, little
in the way of convection is expected tomorrow away from the
coast. Have included VCSH or PROB30 for showers at HUM, MSY, NEW
and ASD where proximity to a a stalled boundary will result in
slightly higher chances.
&&
.MARINE...
Issued at 242 PM CDT Wed Sep 27 2023
Easterly flow will continue to build this evening thru the rest of
the week and upcoming weekend, with attendant headlines in place
for gusty winds mainly for eastern marine zones. Did introduce
exercise caution headlines for a tier of marine zones west of the
advisory going into effect at 9PM this evening. Pressure gradient
winds will remain persistent likely even on Friday with
continuation of headlines likely. This extended period of easterly
fetch will steadily build waves/seas with time, reaching 3 to 5
feet, with the higher end of the range likely for outer 20-60nm
zones. Otherwise, will monitor the easterly flow piling up water
along east-facing shorelines, perhaps causing minor problems for
typical trouble spots, but not seeing strong indications of
impactful coastal flooding concerns at this time. Shower/storm
chances will remain elevated across marine zones with the main
impacts being locally stronger winds in any squalls, and isolated
waterspouts. Activity continues into early next week, but becomes
more hit-or-miss going into mid-week mainly in association with
warmer shelf water activity in the overnight/early morning hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 67 90 66 93 / 0 0 0 0
BTR 71 92 71 93 / 0 10 10 10
ASD 70 88 70 91 / 10 30 20 20
MSY 75 87 76 89 / 10 40 20 20
GPT 70 86 71 89 / 30 30 30 20
PQL 68 88 68 91 / 40 30 20 20
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory until 4 PM CDT Thursday for GMZ532-534-536-
538-555-557-575-577.
MS...None.
GM...Small Craft Advisory until 4 PM CDT Thursday for GMZ534-536-538-
555-557-575-577.
&&
$$
SHORT TERM...KLG
LONG TERM....ME
AVIATION...DM
MARINE...KLG
Area Forecast Discussion
National Weather Service Melbourne FL
933 PM EDT Wed Sep 27 2023
...New UPDATE, MARINE, AVIATION, HYDROLOGY...
.UPDATE...
Issued at 930 PM EDT Wed Sep 27 2023
Persistent light to moderate rain is continuing north of Lake
Kissimmee to Titusville line this evening. This area of rain
should tend to wane through midnight. Convection is also
developing in the warm sector south of the front across the
southern interior. Some recent HRRR runs have and 18z NAM have
been indicating a late evening round of convection across the
southern counties which may linger past midnight. Airmass remains
extremely moist with PWATs in the 2.1 to 2.4 inch range. 15Z XMR
sounding from earlier today recorded a PWAT value of 2.21 inches
which was a record for todays date. Afternoon and evening rainfall
totals reached around 3 inches in spots with minor flooding in a
few locations. For the late evening update, increased pops some in
areas of onoging convection with only minor adjustments to the
overnight forecast brining a slight shower chance for most of the
interior for much of the night. With weak steering flow and deep
moisture there remains the risk of localized heavy rainfall which
should favor the srn interior and portions of the east coast
overnight. Lows will drop into the lower to mid 70s.
&&
.PREV DISCUSSION...
...Daily Threat for Localized Flooding from Heavy Rainfall Will
Continue Through This Weekend...
Current-Tonight...Showers and storms are developing across
portions of east central Florida this afternoon, primarily from
Brevard to Osceola and areas northward. CAM guidance continues to
show increasing coverage over the next several hours, but has now
backed off slightly on coverage across the Treasure Coast. The
15Z XMR sounding shows a measured PWAT of 2.21 inches, indicating
a moist airmass in place across east central Florida. Heavy
rainfall continues to be the primary threat associated with these
showers and storms, with a few Flood Advisories already issued
across portions of east central Florida this afternoon. Quick
rainfall accumulations up to 3 inches is occurring with these
showers and storms, and localized flooding will continue to be
possible, especially across areas that see repeated rounds of rain
and across areas with already saturated soils. Severe parameters
continue to look rather unimpressive today, with minimal shear
and a decrease in CAPE values present in the 15Z XMR sounding
compared to this morning`s 10Z sounding. As a result, storms are
struggling to produce much in the way of gusty winds and lightning
strikes, and this trend will likely continue into this evening.
Boundary collisions between storms and the east coast sea breeze
could lead to funnel cloud development, and a brief tornado and/or
waterspout cannot fully be ruled out through this evening.
In general, shower and storm coverage across the peninsula is
forecast to decrease tonight. However, continued development
across the local Atlantic waters combined with easterly flow
overnight could lead to some showers and storms pushing onshore
along the immediate coast. Cloudy skies will persist into the
overnight hours, with lows in the low 70s.
Thursday-Sunday (previous)...After a few days of flopping back and
forth with a weak cutoff low, global models have converged on a
solution of a positive tilt short wave trough moving slowly east
across the GOMEX Thu-Fri night, then sagging E-SE across FL this
weekend. Broad surface troughing sharpens a bit Fri morning as a
frontal boundary sags into the northern CWA, then becomes more
diffuse again Sat-Sun as the boundary sags across the central
peninsula whilst getting bridged by freshening onshore/ENE winds.
Mean PWAT values are forecast to remain between 2.1" (north) and
2.2"-2.3" south through at Least Sat, with the GFS alone for now in
showing values dropping to 1.8"-2.0".
Forecast keeps PoPS well above normal through this weekend, with
widespread showers/TS (80-90%) through Sat, tapering back slightly
to numerous (70 all but far N Lake/Volusia) Sun. Daily max temps in
the M-U80s (L80s Volusia), with mins in the L-M70s.
Monday-Tuesday (previous)...Pos-tilt H50 trough axis remains over
SOFL early next week, with N-NE flow aloft over ECFL. At the
surface, onshore ENE-NE flow becomes breezy as the local pressure
gradient tightens to about 5MB between JAX-MIA. Deeper moisture will
get shunted to the south/east of the trough axis, resulting in mean
drying across the area. PWATs are progged to drop below 1.5" across
all but the far south, with the GFS is faster and more aggressive in
lowering values than the ECM. However, both models show transient
slugs of deeper moisture pushing onshore/WSW form the Atlantic
across the peninsula behind the initial surge of drier air. Thus the
threat for shows will remain in the forecast. While a slight chance
for TS was kept for now, the risk appears minimal given the strength
of onshore flow that will keep the ECSB diffuse/fast moving.
Max temps in the L-M80s (few U80s possible far south). Mins will
range from U60s-70F to M70s along the coast. Mins at the coast may
need to be tweaked higher given onshore w
&&
.MARINE...
Issued at 930 PM EDT Wed Sep 27 2023
The surface front across the northern waters will move little
overnight with stronger NE winds north of the boundary just north
of the marine area. Will keep seas mainly in the 2-4 range but
some higher seas may reach the far northern waters north of Ponce
Inlet and the Volusia offshore waters later tonight. For the
update will keep peak seas ~ 5ft across the Volusia offshore
waters. Generally onshore flow tonight SE north of the boundary
across the cental and srn waters and NE north of the front. Winds
to around 10 knots for the overnight hours.
&&
.MARINE...
Issued at 930 PM EDT Wed Sep 27 2023
Through Tonight...An active weather pattern will continue through
the overnight hours across the local Atlantic waters. Numerous
showers and storms are forecast to continue to develop, with the
strongest storms producing gusty winds in excess of 35 knots,
occasional cloud-to-water lightning strikes, and locally higher
seas. Decreasing coverage is forecast late tonight, with isolated
to scattered showers and storms potentially moving onshore along
the immediate coast. Seas outside of convection will remain 2 to
3 feet across the local Atlantic waters overnight. Northeast to
southeast winds will slightly veer overnight, becoming south to
southwest, staying between 5 to 10 knots.
Thursday-Sunday (previous)...Broad inverted surface trough will
remain draped across ECFL and the local waters through Fri. The
quasi-stationary front to our north will gradually sag south into
the local waters this weekend, with modest freshening of
winds/building of seas by Sun. Winds/seas very likely to approach
cautionary levels, with potential for Advisory conditions early
next week. 3-5ft seas Thu-Sat build to 4-6ft Sun.
&&
.AVIATION...
(00Z TAFS)
Issued at 854 PM EDT Wed Sep 27 2023
Convection and areas of light rain should be generally on the wane
in the 03z-05z time frame with most CIGs VFR outside of SHRA
through 07z-09z. Some MVFR to possibly IFR low cloudiness may
redevelop generally north of a KISM-KTIX line late tonight. High
rain chances on Thu will lead to periods of +RA and lower MVFR
CIGS and VSBY reductions in heavy rain with afternoon convection
in moisture laden airmass. Have added TEMPOs to most terminals
btwn 19z-23z when SHRA/TSRA will be highest.
&&
.HYDROLOGY...
Issued at 930 PM EDT Wed Sep 27 2023
The Saint Johns River at Astor continues near Action Stage this
evening, around 2.1 feet. River levels are forecast to rise to
atleast 2.2 ft and possible to the minor flood stage of 2.3 ft as
additional heavy rain works into the river basin through the
upcoming weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 74 84 73 83 / 50 80 60 80
MCO 73 87 73 86 / 60 80 50 80
MLB 73 86 74 87 / 50 80 60 80
VRB 73 86 73 87 / 50 80 60 80
LEE 73 86 73 85 / 50 80 40 80
SFB 73 87 73 86 / 50 80 50 80
ORL 74 88 74 87 / 60 80 50 80
FPR 73 87 74 87 / 50 80 60 80
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Volkmer/Pendergrast/Watson/Haley
Area Forecast Discussion
National Weather Service Morristown TN
1018 PM EDT Wed Sep 27 2023
...New UPDATE...
.UPDATE...
Issued at 1010 PM EDT Wed Sep 27 2023
Showers and thunderstorms have ended for the evening and skies
were clearing from the west. At the same time showers and storms
were moving across the lower Ohio Valley late this evening with an
upper level impulse in the cyclonic flow around the upper low now
over Lake Michigan and Indiana/Illinois. This impulse will move
east southeast to central and eastern Kentucky after midnight and
should reach the northern plateau before 12z Thursday. Rain
chances will increase in the NW part of the area late tonight as
the impulse moves east. Overall forecast looks good. Updated
forecast to end rain chances this evening. Also had to adjust
temperatures down a few degrees because of cooling from storms.
Some fog is possible later tonight but mainly south and southeast
otherwise clouds moving back into the region from the northwest
will decrease fog chances. Updated forecast sent.
&&
.UPDATE...
Issued at 611 PM EDT Wed Sep 27 2023
Line of showers and storms that formed from outflow boundaries
early in the afternoon near the KY/TN border across the northern
Cumberland Plateau kept going into east central TN and southeast
TN so added rain chances in the far south and continued them in
the northeast for the next couple hours. Convection is weakening
as it moves into the southern and far northeast counties now so
expect precipitation to end around 23 to 00Z or shortly after
sunset. There may be fog forming across much of the area with the
afternoon rainfall.
&&
.SHORT TERM...
(This evening through Thursday)
Issued at 333 PM EDT Wed Sep 27 2023
Key Messages:
1. Showers and isolated storms this afternoon mainly north of
I-40.
2. Another round of showers possible Thursday morning.
Discussion:
An upper low continues to rotate across Illinois this afternoon
placing the region within diffluent upper flow. RAP analysis places
a 50-60 knot upper level jet from the Tennessee Vally northeast into
portions of the central Appalachians and mid Atlantic. Increased
forcing for ascent continues to overspread the area this afternoon
as outflow from previous convection has fired showers and storms.
This activity will continue to move eastward over the next couple
of hours within a moist and unstable airmass characterized by
MLCAPE`s around 500-1000 J/kg. So far most of this activity has
remained below severe limits, although a few strong updrafts have
been noted a few times. Weakening instability to the east should
tend to weaken this activity into this evening. A few strong
storms are still possible.
The upper low moves into the Great Lakes tonight and on Thursday
with the region still within cyclonic flow. An upper level impulse
looks to move through this flow and across the Ohio Valley resulting
in increased 925-850mb flow Thursday morning. Showers and some
embedded storms are expected across portions of central/eastern
Kentucky early Thursday morning and may begin to move south before
weakening as they move into the MRX forecast area. Carried a small
area of likely PoPs across the far northwest counties for a few
hours with chance to slight chances elsewhere. Scattered showers and
storms are possible through the rest of the afternoon.
&&
.LONG TERM...
(Thursday night through next Wednesday)
Issued at 333 PM EDT Wed Sep 27 2023
Key Messages:
1. Chance of showers and storms to begin the period.
2. Dry this weekend and continuing through the end of the extended
with slightly above normal temperatures.
Discussion:
We begin the period with a closed low to our north across the Ohio
River Valley and a trough axis centered through our area. Moisture
will be limited with this system as we are on the southern fringe.
Because of this, coverage of showers will be limited as well. A few
areas, generally along I-40 and northward, will see slight chance POP
from Thursday night through Friday. A rumble of thunder can`t be
ruled out. Most areas will stay dry but those who receive rain will
only a few tenths of an inch at best.
The good news is the rest of the period will be warm and dry as high
pressure settles in across the region. The bad news is that we will
be warm and dry and we could use some rainfall across the region as
things continue to dry out.
&&
.AVIATION...
(00Z TAFS)
Issued at 739 PM EDT Wed Sep 27 2023
Showers and storms are now moving out of east Tennessee. So VFR
conditions next few hours. Clouds are expected to stick around and
lower by or before 12Z Thursday for MVFR conditions. Also some fog
down to 2 miles at TRI and ceiling at 2000 feet. MVFR ceilings may
move out first at TRI but stick around longer at TYS and CHA
Thursday. VFR conditions expected at CHA and TYS by 15-18Z Thursday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 62 83 63 85 / 30 10 10 0
Knoxville McGhee Tyson Airport, TN 60 82 61 83 / 20 20 10 10
Oak Ridge, TN 60 80 61 83 / 20 30 20 10
Tri Cities Airport, TN 55 78 57 78 / 30 20 20 10
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...TD
AVIATION...TD
Area Forecast Discussion
National Weather Service Phoenix AZ
419 PM MST Wed Sep 27 2023
.Update...Updated Aviation
&&
.SYNOPSIS...
Dry conditions will continue through this weekend with above
normal temperatures continuing through the next couple of days. A
weather system moving into the region will bring increasing winds
and much cooler temperatures heading into this weekend. Below
normal temperatures settle into the region by Sunday and continue
into early next week.
&&
.DISCUSSION...
Afternoon visible satellite imagery showed mostly clear skies across
much of the state while high clouds are seen increasing to the west
across southern California. Today will be the warmest day for the
rest of the week as we remain under the influence of the
subtropical ridge of high pressure situated to the south centered
near southern Baja. RAP analysis early this afternoon showed 500
mb heights around 590 dm, which is around the 90th climatological
percentile for this time of year. As a result, temperatures
continue to remain above seasonal normals with around a 20-30%
chance for tying the daily record high today in Phoenix. For Yuma
and El Centro, high temperatures this afternoon will be out of
reach of any record highs, which are 111 degrees for both
locations. These above normal temperatures will lead to areas of
Moderate HeatRisk through this afternoon, primarily across the
lower deserts of south-central Arizona.
Going through the remainder of the week, temperatures will cool and
winds will increase over the next several days as the subtropical
ridge breaks down and a strong trough, currently situated over the
Pacific Northwest, digs south into the Great Basin heading into this
weekend. Ensemble clusters are in great agreement with the evolution
of this trough, with increasing confidence that we will see strong
winds across the region for the start of this weekend. The ECMWF
Extreme Forecast Index (EFI) continues to indicate this threat for
anomalously strong winds across the region for Saturday. Breezy
conditions will increase Thursday and Friday as low level winds
increase ahead of the trough with the strongest winds expected
Saturday. Winds on Saturday are expected to climb upwards of 30-40
mph across most of the forecast area with locally higher winds in
excess of 40 mph, mainly across Imperial County and the higher
terrain east of Phoenix. The latest NBM continues to show high
probabilities (>70%) for peak winds gusts in excess of 40 mph
Saturday in the aforementioned areas. Thus, Wind Advisories will
likely be needed as we get closer if these trends continue. With
expected winds of this magnitude, areas of blowing dust could
develop, particularly in dust prone areas across Imperial County.
This weather system is expected to be dry for our area with only a
slight bump in moisture across the region. Any rain chances are
expected to remain confined to the northern Arizona high terrain
this weekend with dry conditions favored to persist across our area.
However, we will see temperatures falling well below normal as much
cooler air settles into the region. The latest NBM shows afternoon
high temperatures falling into the 90s across the lower deserts by
Saturday before further dropping into the 80s Sunday. Low
temperatures are forecast to fall into the upper 50s to low 60s
across the lower elevations by Monday morning of next week. These
will be some of the coolest temperatures experienced since early
May. Ensemble guidance show negative height anomalies lingering into
the first part of next week before rebounding during the middle
part of the week. Given this, below normal temperatures are
favored to persist into the first part of next week with
temperatures gradually trending upward.
&&
.AVIATION...Updated at 2320Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected during the TAF period. Winds
will follow familiar diurnal tendencies, with periods of
variability during the overnight hours. Speeds will remain
generally below 10 kts through tomorrow morning. SCT-BKN high
level clouds will continue to move over the region this evening
and tonight, while FEW mid- level clouds filter in starting
tomorrow morning.
&&
.FIRE WEATHER...
Dry conditions will prevail this week with above normal high
temperatures pushing towards record territory in the Phoenix area
through today, though cooling into a below normal category over the
weekend. Afternoon Min RHs Thursday and Friday will be in the
10-20% range for most areas, while overnight Max RHs tonight
around 20-45% increase going into the weekend. Winds will increase
over the next several days as a weather system approaches the
region with the strongest winds expected on Saturday. Gusts
Saturday may climb upwards of 30-40 mph in many areas with locally
higher gusts in excess of 40 mph possible across Imperial County
and the southern Gila County high terrain. Strong winds combined
with low RHs Saturday will lead to elevated fire weather concerns.
&&
.CLIMATE...
Records highs this week:
Date Phoenix Yuma El Centro
---- ------- ---- ---------
Sept 27 107 in 2009 111 in 1963 111 in 2009
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Smith
AVIATION...RW
FIRE WEATHER...Smith
CLIMATE...18
Area Forecast Discussion
National Weather Service Raleigh NC
923 PM EDT Wed Sep 27 2023
.SYNOPSIS...
Cloudy skies with below normal temperatures will persist through the
end of the week as a strong area of high pressure remains to our
north. Clouds will decrease and temperatures will return to near
normal values by this weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 920 PM Wednesday...
The 00Z surface analysis shows the ridge still extending southwest
through central NC from a 1030mb high over Quebec. Aloft, the H25
and H5 lows remain roughly over southern Lake Michigan/northern
IL/IN, with the trough extending southward through the MS Valley.
Central NC is roughly situated under the entrance region of the H25
jet. At H7, there is still a good bit of dry air, with dewpoint
depressions ranging from 5 to 15 degrees across the area. Conversely
at H85, dewpoint depressions are generally 5 degrees or less. Cool
northeasterly flow should persist, with patchy drizzle possible
across the area through tonight. There is still a slight chance for
some rain over the Coastal Plain later tonight/early Thu morning
associated with a brief period of increased isentropic lift.
However, given the inconsistency in the model guidance, confidence
remains low at this time and will thus leave it out of the forecast
with this update. No major changes to low temperatures, still expect
mid 50s to low 60s from north to south.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 141 PM Wednesday...
The surface ridge will remain north of the area on Thursday,
although it will weaken a bit and shift eastward, decreasing its
influence across NC in the process. Skies will start off the day
overcast although there should be at least some breaks in the clouds
by the afternoon hours. Temps will be warmer than today although
still below normal with highs ranging from the upper 60s in the
north to the mid 70s in the south. Lows in the mid 50s to lower 60s.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 141 PM Wednesday...
A sustained period of dry weather is expected in the extended
forecast. Although weak low pressure is expected to form east of the
Delmarva Peninsula Friday with the aid of an upper level trough, any
rain with that system should be contained to the immediate
coastline. A ridge of high pressure should re-establish itself over
the Great Lakes by Saturday night, and this high should remain along
the East Coast through the middle of next week. Temperatures should
generally be near normal, although temps will be a couple degrees
cooler Friday with additional cloud cover.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 714 pm Wednesday..
Through 00Z Friday: Widespread MVFR cigs across the area at the
moment due to cool northeasterly onshore flow. Latest HRRR shows a
surge of low level moisture from the northeast overnight, which will
lower cigs below 1K ft agl across much of central NC between 06-14Z.
Patchy drizzle will also continue at times although the
duration/intensity should not have negative aviation impacts. Cigs
will improve to MVFR after 14Z, and remain MVFR across much of
central NC through the afternoon hours.
After 00Z Friday: Persistence will carry through Thursday night with
cool northeasterly flow continuing. Although by Friday into early
next week, it appears conditions will become more favorable for VFR
weather as the flow takes on a more northerly component.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Leins
NEAR TERM...KC
SHORT TERM...Leins
LONG TERM...Green
AVIATION...np/Leins
Area Forecast Discussion
National Weather Service Blacksburg VA
837 PM EDT Wed Sep 27 2023
.SYNOPSIS...
High pressure over New England will build southward slowly over
the next few days, wedging against the eastern slopes of the
Appalachians, and bringing abundant cloud cover, patchy light
rainfall and below normal temperatures. Low pressure from the
upper Midwest will drift slowly east through the end of the
week, maintaining a chance of rain into Friday. Dry weather and
warmer temperatures are expected for the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 825 PM EDT Wednesday...
Key Message:
- Cloudy with fog and drizzle overnight
- Little change to current forecast
Well defined wedge of high pressure will remain over much of the
region tonight and Thursday. The western edge of the low clouds
extended from near Bluefield, WV into western sections of Ashe
and Watauga Counties in NC. High clouds covered the western
slopes of the Appalachians as scattered showers and isolated
thunderstorms moved across eastern Kentucky and central West
Virgina. This precipitation weakened as it moves east from a
more favorable environment into the much more stable air within
in the wedge.
Have added patchy drizzle and expanded the extent of light fog
overnight. No changes made to low temperatures at this time.
As of 1030 AM EDT Wednesday...
We continue to experience widespread overcast skies and gray
drizzly weather. The Canadian high pressure that is causing our
current wedge has not been able to push the wedge all the way
into our western zones, as satellite shows parts of Tazewell,
Smyth and Mercer counties with only scattered clouds.
A mid-level low over the Midwest will make a more significant
move towards our area, spawning showers and even some storms in
teh KY/TN valley today and then moving those showers into WV on
Thursday. The CAD on our side of the mountains should provide a
dome of stability which will cut off most measurable rainfall
Thursday. Some portions of far southwestern VA and southeastern
WV could still receive a few hundredths however.
Temperatures remain below normal today, with highs only breaking
into the low/mid 60s. Thursday will be close to normal this time
of year, with thermometers likely showing mid to upper 60s and
low 70s.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 1200 PM EDT Wednesday...
Confidence is high for lingering rain through Friday, but drier
weather should return by Saturday.
An upper level low will pass to the north during Thursday night into
Friday. Meanwhile, a cool and moist northeast flow will persist due
to high pressure still wedged against the eastern slopes of the
Appalachian Mountains. Thus, mostly cloudy skies with a chance of
light rain should remain through Friday. Drier air starts to arrive
by Friday night into Saturday as the upper level low heads off the
East Coast. High pressure will completely take control across the
Mid Atlantic on Saturday night.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 1200 PM EDT Wednesday...
Confidence is high for dry and warm weather to start October.
High pressure will keep control across the Mid Atlantic to start the
new week and the month of October. Although the flow should stay
mostly out of the north, temperatures should rebound back to normal
values for this time of year and may even trend a few degrees above
normal as the week progresses. All the models continue to show good
agreement with the overall synoptic pattern of an upper level ridge
staying just to the west of the Appalachian Mountains.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
As of 835 PM EDT Wednesday...
Well defined wedge of high pressure will remain over much of the
region tonight and Thursday. The western edge of the MVFR clouds
extended from near KBLF to west of KTNB. High clouds covered
the western slopes of the Appalachians as scattered showers and
isolated thunderstorms moved across eastern Kentucky and central
West Virgina. This precipitation weakened as it moved east from
a more favorable environment into the much more stable air
within in the wedge. Expect the low clouds to expand west into
KBLF and ceilings will lower into the IFR to LIFR range.
Expect MVFR fog and patchy drizzle to develop and expand in
coverage overnight. Ridges will be in the clouds resulting in
MVFR to IFR visibility.
Very slow improvement in conditions is expected after 13Z/9AM on
Thursday. Some of the models, Including the RAP and 1D NBM
viewer indicated the drier air that was over Maryland and
northeast Virginia this evening will progress south into the
piedmont tomorrow afternoon. Have KLYH becoming VFR after
18Z/2PM but with only moderate confidence in this occurrence.This
timing was based on the 3kmNAM Bufkit forecast sounding.
Above average confidence for wind.
Average confidence for ceiling and visibility.
EXTENDED AVIATION OUTLOOK...
A high pressure wedge with low ceilings, drizzle, fog, and
periods of light rain will continue through Saturday. Late
Saturday into Sunday we should see some improvement with
northerly surface winds bringing drier air into the region.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...VFJ
NEAR TERM...AMS/VFJ
SHORT TERM...PW
LONG TERM...PW
AVIATION...AMS/VFJ