Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/21/24
Area Forecast Discussion
National Weather Service Cheyenne WY
529 PM MDT Sat Apr 20 2024
.KEY MESSAGES...
- Freezing fog and light to moderate snowfall will be the main
concerns through mid-afternoon across the South Laramie Range,
Cheyenne Ridge, and southern Nebraska panhandle. Minimal snow
accumulation expected, mainly on grassy and elevated surfaces.
Roadways may be slick, especially bridges and overpasses.
- Warming back up to near-normal, mild temperatures Sunday
through Thursday along with a chance of late day showers and
thunderstorms for Wednesday and Thursday.
- Cooler and more unsettled weather is likely for Friday and
Saturday.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 216 PM MDT Sat Apr 20 2024
While light snow and areas of dense fog continue from the I-80
Summit through the southern Nebraska panhandle, conditions are
expected to begin clearing later this afternoon. However, these
areas will still likely not see the sun today as the low clouds are
expected to stick around through this evening and overnight. Areas
of fog may return later tonight through early tomorrow morning
across these same areas as easterly, upslope flow and low-level
moisture stick around until they are pushed out by the incoming
ridge. Once the winds turn westerly, the fog will likely dissipate
quite quickly due to drier air moving in and downslope winds warming
and further drying the air. Latest hires guidance overall shows
surface winds starting to turn westerly sometime between 08Z and
12Z. Looking at soundings, the HRRR pushes the fog out the quickest,
and has arguably been known to push fog/low-level moisture out too
quickly, the NAM Nest holds onto it until well into the afternoon.
But, the NAM Nest tends to not handle boundary layer moisture very
well for this area. That being said, the reality will likely be
somewhere in the middle with fog settling back in late tonight and
continuing until early to mid-morning Sunday with some areas along
the Cheyenne Ridge holding onto it longer than others. As the warmer
air moves into southeast Wyoming and western Nebraska Sunday,
afternoon high temperatures are forecast to be in the upper 50s to
60s with the cooler temperatures being between Laramie and Sidney.
Clear skies and mostly light winds are expected Sunday with minimal
weather concerns once the fog clears.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 216 PM MDT Sat Apr 20 2024
Monday...Brisk northwest flow aloft will produce a breezy to windy
day along and west of Interstate 25. Mild temperatures once again
with 700 mb temperatures near 5 Celsius.
Tuesday...Slightly cooler at most locations in the wake of a weak
cold frontal passage under northwest flow aloft.
Wednesday...Ridging aloft builds across the region which will
produce a decent warming trend as 700 mb temperatures rise to near 7
Celsius, yielding maximum temperatures in the upper 60s and lower
70s. Looks like there may be enough low and mid level moisture
combined with easterly upslope winds to spark isolated to scattered
afternoon showers and thunderstorms.
Thursday...The next progressive shortwave trough aloft moves across
Wyoming and Colorado, helping to produce scattered afternoon and
evening showers and thunderstorms. Continued relatively mild based
on the projected 700 mb temperatures.
Friday...Cooler and more unsettled weather expected with adequate
low and mid level moisture, and low level convergence along a cold
front.
Saturday...Cool and unsettled weather looks to continue as a series
of shortwave troughs aloft move overhead under southwest flow aloft.
Scattered showers and a few thunderstorms again possible based on
instability parameters.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 523 PM MDT Sat Apr 20 2024
Surface high pressure and localized upslope will continue the
low clouds and possible fog overnight for far southeast Wyoming
and the southern Nebraska Panhandle, then a passing weather
disturbance will clear out the low clouds Sunday morning.
Wyoming TAFS...For Rawlins and Laramie, scattered to broken
clouds from 6000 to 15000 feet will occur early this evening,
then skies will be clear. Winds will gust to 26 knots at Rawlins
after 15Z Sunday.
For Cheyenne, ceilings will vary from 800 to 1500 feet until
12Z Sunday, with visibilities of one mile in fog from 06Z to
12Z, then skies will be clear after 12Z Sunday.
Nebraska TAFS...For Chadron, Alliance and Scottsbluff, scattered
to broken clouds from 3000 to 9000 feet will occur early this
evening, then skies will be clear.
For Sidney, ceilings will vary from 1100 to 2800 feet through
14Z Sunday, with visibilities of one mile in fog from 06Z to
14Z, then skies will be clear after 14Z Sunday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...LEG
LONG TERM...RUBIN
AVIATION...RUBIN
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
324 PM PDT Sat Apr 20 2024
.SYNOPSIS...A dissipating cold front will bring a slight chance for
drizzle to the North Coast through early this evening. Gusty northerly
breezes are forecast to develop later tonight behind the front
and then strengthen on Sunday. Otherwise, dry weather with above
normal temperatures are forecast for Sunday and Monday.
&&
.DISCUSSION...Visible satellite imagery showed a mass of thick
clouds associated with a dissipating cold front just offshore the
North Coast this afternoon. ARW and HRRR models continues to
indicate potential (10-20% chance) for minuscule amounts
(0.01-0.04in) of precip (drizzle) through early this evening.
Breezy northerly winds will develop later tonight as the front
moves to southeast.
Otherwise, dry weather is forecast to continue for the remainder
of the weekend into early next week. Interior temperatures will
remain above normal (mid 70s to mid 80s) through Tuesday. Monday
will most likely be the warmest day as offshore flow strengthens.
Warmest interior valleys will likely (70-90% chance) peak in the
low to mid 80s on Monday.
Breezy to windy conditions are expected for coastal areas on Sunday
as a cold air surge develops offshore in the wake of the front.
Peak gusts (mostly in the late afternoon and early evening) of 25 to
35 mph are forecast. Granted, higher gusts (40-50 mph) are
probable (>70% chance) for wind prone locations; the King Range,
coastal headlands of SW Humboldt and windy point or Pt St George,
On Tuesday, a 500mb shortwave trough will approach the Pac NW.
Deterministic model guidance continues to indicate increasing
buoyant energy and instability for possible (20-30% chance)
showers and thunderstorms across the interior - mostly Trinity
County - on Tuesday. Also, a closed cyclonic circulation evident
at 925mb will likely induce a southerly wind reversal and a push
of marine air/low clouds from the SW Monday night into Tue morning.
Some cooling is expected on Tue, but high temps will likely (>60%
chance) remain above normal (lower to mid 70s) until the air mass
cools down more drastically toward the end of the week.
Potential for precipitation will increase mid to late next week
as a colder 500mb trough (temps <-25C). Timing has tightened up to
Thu-Fri with 24 hours probabilities for > 1 inch in 24 hours for
the western slopes of Del Norte and northern Humboldt Counties
around 20 to 30%. There is still a great deal of variability with
timing and precip amounts. Also, there are indications for a
secondary trough in the NW flow on the backside of the main trough
that may spark up more showers Friday night into Saturday (10-20%
chance). It is more certain that interior high temperatures will
cool down by late week - mostly in the 60`s. If snow levels fall
to 5000 feet on Friday, high temps will struggle to reach the
lower 40s in the high mountains Fri-Sat. Precipitation amounts
are forecast to be light, but this time of year even light amounts
will have impacts on outdoor plans or activities. Stay tuned. DB/ZVS
&&
.AVIATION...Latest space pictures show mid cloud spreading over the
Redwood Coast this afternoon ahead of a weak frontal passage. Some
drizzle is expected with this front, and periods of IFR are possible
later this afternoon as it passes overhead. Space pictures also show
rapid clearing and subsidence in the cold sector behind the
boundary. Thus any low cloud associated with this feature that moves
onshore this afternoon and evening should mix out overnight,
accompanied by developing NW winds. Otherwise, VFR conditions are
expected across the interior. TDJ
&&
.MARINE...Northwesterly wind will build through the waters from
north to south with gusts over 21 kts in the outer waters later this
evening. Wind will continue to increase with gale force gusts
throughout the outer waters during the day on Sunday. These reach
the inners this evening, and gale force gusts should still be
expected right along shore around Cape Mendocino and Pt. St. George.
Strong winds will build steep short period seas in excess of 10 feet
by Sunday afternoon.
Weak high pressure building over California will help gradually
shunt the strongest wind offshore starting Monday, which will allow
at least coastal conditions to gradually calm early this week. Short
period waves dominate the sea state through early week, with a mid
period swell up to 5 feet building Sunday. TDJ
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
None.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory from midnight tonight to 9 PM PDT
Sunday for PZZ450.
Small Craft Advisory from 3 AM to 9 PM PDT Sunday for
PZZ455.
Small Craft Advisory from 9 PM this evening to 3 PM PDT
Sunday for PZZ470.
Gale Warning from 3 PM Sunday to 3 AM PDT Monday for PZZ470.
Small Craft Advisory until 3 AM PDT Sunday for PZZ475.
Gale Warning from 3 AM to 9 PM PDT Sunday for PZZ475.
&&
$$
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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
520 PM MDT Sat Apr 20 2024
...New AVIATION...
.SYNOPSIS...
Issued at 220 PM MDT Sat Apr 20 2024
Dry west flow aloft will dominate the weather for much of the new
week ahead. Temperatures will remain well above normal, especially
mid-week. Afternoon breezes will pop up, but for this time of the
year, winds will remain tame. Our next weather of note appears to
be next Saturday and Sunday, when a Pacific storm system will
bring in strong winds and a chance of mountain showers.
&&
.DISCUSSION...
Issued at 220 PM MDT Sat Apr 20 2024
For the most part, a quiet week ahead as zonal flow holds court
through about Wednesday. In the short term, dry-line moved about
as far west as the Cont Divide, but is already mixing out back to
Deming. HRRR shows this mixing/drifting east will make it to
western Sierra and Dona Ana Counties this evening before
proceeding back west to around the Arizona line late tonight.
Moisture (dewpoints in the upper 30s/mid 40s) will be enough to
form CU/TCU over the mountains through early this evening, but
little else. Strong low level east flow pushed stratus/fog up into
east slopes of our terrain along the eastern CWA. Expect this to
continue overnight before dissipating Sunday. Aloft short wave is
just about to exit the eastern CWA. Otherwise aforementioned zonal
flow pretty clean through Wednesday. Previous model runs did show
jet streak/short wave in sub-tropical jet moving east, just south
of the CWA and possibly a risk of a shower for Hudspeth Co Sunday
night. Latest models now show this feature a bit further south,
more of a threat to the Big Bend than our southeastern CWA.
Temperatures will remain well above normal. Near record highs
possible Tuesday and Wednesday.
Late week has the potential for some impactful weather. Merged
Pacific low into the sub-tropical jet will move to Arizona
Thursday morning and across northern New Mexico Thursday afternoon
for a windy afternoon. Winds look to be sub advisory at this time.
A second Pacific storm system drops in over the Great Basin
Saturday with attendant increase in afternoon winds. Latest model
suite has trended down slightly for Saturday winds, but could
still be looking at advisory criteria winds. Upper low likely too
far north for even most mountain showers, but the Gila/Black Range
could still see a stray shower.
&&
.AVIATION...
(00Z TAFS)
Issued at 514 PM MDT Sat Apr 20 2024
VFR conditions through the period with FEW100 SCT250, but
dissipating aft 00-01Z. There will be low, east slope hugging
stratus along the east slopes of the Sacramento Mtns...BKN-
OVC010 with patchy 3SM BR, with mountain obscurations. Surface
winds generally from the east/southeast 10-15 knots.
&&
.FIRE WEATHER...
Issued at 220 PM MDT Sat Apr 20 2024
Not much fire weather concerns early part of forecast with dry
weather and just breezy afternoons through Wednesday. Winds start
ramping up Thursday into the weekend and drive humidity down.
Thursday will see a windy afternoon and then Saturday will be
very windy in the afternoon. So we are looking at near-critical to
Red Flag criteria days, mainly Thursday and Saturday.
Min RH: Lowlands 18-30% Sunday and Monday decreasing to 8-13%
Tuesday through the rest of the week. Mountains 25-40% Sunday and
Monday decreasing to 10-20% Tuesday through the rest of the week.
Vent rates fair-good Sunday and Monday improving to excellent
Tuesday through Saturday.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 50 77 50 84 / 0 0 0 0
Sierra Blanca 43 67 43 76 / 0 0 10 10
Las Cruces 47 78 47 82 / 0 0 0 0
Alamogordo 43 75 43 80 / 10 0 0 0
Cloudcroft 34 54 32 58 / 10 10 0 10
Truth or Consequences 48 76 49 81 / 0 0 0 0
Silver City 46 72 44 75 / 0 0 0 0
Deming 46 79 46 82 / 0 0 0 0
Lordsburg 46 79 50 83 / 0 0 0 0
West El Paso Metro 49 75 48 82 / 0 0 0 0
Dell City 41 68 40 81 / 0 0 0 0
Fort Hancock 44 76 45 84 / 0 0 10 10
Loma Linda 43 67 41 75 / 0 0 0 0
Fabens 46 78 47 84 / 0 0 0 0
Santa Teresa 45 75 45 82 / 0 0 0 0
White Sands HQ 49 75 48 81 / 0 0 0 0
Jornada Range 43 76 41 80 / 0 0 0 0
Hatch 44 79 44 83 / 0 0 0 0
Columbus 47 79 49 82 / 0 0 0 0
Orogrande 44 72 43 79 / 0 0 0 0
Mayhill 35 60 34 72 / 10 0 0 10
Mescalero 37 65 36 69 / 20 0 0 10
Timberon 34 62 32 68 / 0 0 0 0
Winston 42 71 41 74 / 0 0 0 0
Hillsboro 44 76 42 79 / 0 0 0 0
Spaceport 43 77 42 79 / 0 0 0 0
Lake Roberts 42 74 40 76 / 0 0 0 10
Hurley 42 74 41 78 / 0 0 0 0
Cliff 36 82 38 83 / 0 0 0 0
Mule Creek 33 78 35 79 / 0 0 0 0
Faywood 45 73 42 76 / 0 0 0 0
Animas 45 80 49 84 / 0 0 0 0
Hachita 45 79 48 82 / 0 0 0 0
Antelope Wells 46 79 48 84 / 0 0 0 0
Cloverdale 50 77 48 79 / 0 0 0 0
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...None.
&&
$$
FORECASTER...14-Bird
Area Forecast Discussion
National Weather Service Peachtree City GA
1055 PM EDT Sat Apr 20 2024
...Evening Update...
.UPDATE...
Issued at 1053 PM EDT Sat Apr 20 2024
Made some minor tweaks to precip chances over the next few hours
based on overall radar trends. Otherwise, forecast remains on
track. Some initial thunder possible with rain/storms pushing into
area now, but not expecting any more severe weather overnight.
Lusk
&&
.SHORT TERM...
(This afternoon through Sunday)
Issued at 211 PM EDT Sat Apr 20 2024
Weak surface boundary is situated across south central Georgia this
afternoon. The old boundary will remain nearly stationary through
Sunday afternoon before shifting southward into northern Florida by
the evening. High pressure begins to build in from the west
overnight Sunday.
The nearly stationary front will be the main focus for any
precipitation development overnight and into the first half of
Sunday. In addition, several strong shortwaves will move east in the
flow, providing an excellent source of lift along with the
convergence along the front. The best CAPE may be shunted to
southern portions of the state, but there should be enough surface
instability available for isold to scattered thunderstorms through
Sunday afternoon, especially along and just south of the front. To
the north of the boundary, widespread showers are most likely with
some embedded thunder. Strong storms are possible, especially this
afternoon across the southern third of the CWA. An isolated severe
thunderstorm cannot be ruled out. The potential for severe weather
should wane with the loss of heating, but isolated strong storms
could be possible overnight/early Sunday - especially south of Macon
to Columbus. Hail and gusty winds will be possible with any strong
storms. With PWATs around 1.5" south of I-20, locally heavy rainfall
will also be possible.
There is some differences between the models on the overall
evolution of the pops with this system. The HRRR performed fairly
well in the short term period yesterday, so have trended this way for
the afternoon. The ARW precip pattern looks more reasonable for
overnight and the first half of Sunday and have trended close to it
during this period. Drying/clearing is expected for late tomorrow
afternoon into the overnight hours.
Temps tomorrow will likely average around 10 to 20 degrees below
normal for this time of year. Thick cloud cover and widespread rain
will limit heating across much of the forecast area. A cooler and
drier airmass will settle across north and central GA Sunday night.
Mins should range from the mid 30s in the far NE mtns to around 50
in the SE. Will have to monitor the far NE portions of the state for
frost potential. Winds may diminish, but there could be enough
clouds around to prohibit good radiational cooling and keeping frost
more patchy in nature.NListemaa
&&
.LONG TERM...
(Monday morning through next Friday)
Issued at 211 PM EDT Sat Apr 20 2024
The bulk of the long term period will be fairly nondescript after
the departure of Sunday`s rainfall. Surface high pressure will slide
overhead from Monday into Tuesday, bringing sunny, dry, and cooler
conditions. Monday will be the coolest day of the period with highs
remaining in the 60s areawide, some 10+ degrees below normal.
Tuesday morning lows will dip at least into the 40s areawide, with
some upper 30s possible across far north Georgia as clear skies and
calm winds maximize radiational cooling.
A warming trend then begins from Tuesday into midweek as low level
flow becomes southerly as the surface high shifts eastward. Still,
Tuesday and Tuesday night will remain on the cool side, likely a few
degrees below normal. A weak frontal boundary looks to dip into the
area from Wednesday into Thursday, though the forecast remains dry
given very little moisture in place. In fact, rain chances look to
hold off until at least next weekend. Temperatures by next weekend
also rebound, likely returning a few degrees above normal.
RW
&&
.AVIATION...
(00Z TAFS)
Issued at 805 PM EDT Sat Apr 20 2024
Wet forecast for most all TAF sites. Rain should move into metro
sites by 03Z timeframe and become steady by the early morning
hours, continuing into the early afternoon before tapering off by
19-21Z. Not expecting TS at this time at metro TAF sites. Cigs
will dip through the overnight, becoming IFR by 09-10Z. IFR
conditions expected to linger through morning and early afternoon
before improving to MVFR by 19-20Z as rain begins to end. Winds
will be NW at metro sites, 5-10 kts. Winds will be more VRB at
AHN, MCN, and CSG. MCN and CSG will have lower overall rain
chances, with PROB30 in place for tomorrow for SHRA.
//ATL Confidence...00Z Update...
Medium-high on morning cigs, high all others.
Lusk
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 53 59 47 65 / 60 70 10 0
Atlanta 52 57 47 64 / 60 70 10 0
Blairsville 45 55 39 63 / 60 70 10 0
Cartersville 47 59 41 66 / 60 70 0 0
Columbus 56 61 48 69 / 60 50 10 0
Gainesville 52 59 46 64 / 60 70 10 0
Macon 59 62 50 67 / 60 40 10 10
Rome 49 62 43 66 / 70 70 0 0
Peachtree City 51 59 45 66 / 60 70 10 0
Vidalia 65 72 53 66 / 30 50 10 10
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...NListemaa
LONG TERM....RW
AVIATION...Lusk
Area Forecast Discussion
National Weather Service Green Bay WI
1014 PM CDT Sat Apr 20 2024
Updated aviation portion for 06Z TAF issuance
.KEY MESSAGES...
- Elevated fire weather conditions are likely Sunday and Monday
during the afternoon and early evening hours due to relative
humidities ranging from 20 to 30 percent and winds of 15 to 25
mph.
- The next chance for precipitation is Monday evening through
Tuesday. A few thunderstorms are possible Tuesday, but severe
weather is not expected.
&&
.DISCUSSION...
Issued at 249 PM CDT Sat Apr 20 2024
Short Term...Tonight and Sunday
Low level moisture remains locked in the region for the early
afternoon hours, keeping low clouds in for at least the middle to
late afternoon before incoming surface ridging begins to scour out
the lingering cloud cover. As a result, lowered the afternoon high
temperatures a few degrees.
Tonight, surface ridging should fairly quickly bring an end to
lingering low clouds from northwest to southeast, with clear skies
across most of the region by the overnight hours. The only
exception to this could be areas near the Upper Peninsula border,
as satellite and water vapor trends do bring in some additional
high clouds for tonight. Winds should decrease a bit from the
afternoon but could remain breezy overnight, with a few gusts to
around 10 to 15 mph at times. Overnight low temperatures remain in
the upper 20s near the Upper Peninsula border to the lower 30s
near east-central.
Sunday, skies will be largely sunny through the day, which should
allow for some warmer surface temperatures into the 50s and
possibly lower 60s. Deep mixing through ~800-700mb will also mean
another fairly breezy day in the afternoon and evening, and the
potential for fairly low relative humidity values around 20 to 30
percent in the afternoon, which will create a period of elevated
fire weather conditions.
Long Term...Sunday Night Through Saturday
The upper air pattern for next week is pretty typical for this
time of the year, with a few significant weather systems coming by
and temperatures not too far from seasonable averages.
A surface high over the Midwest will allow for clear skies Sunday
night, with temperatures falling below freezing thanks to dry air
and light winds. Winds will become southwesterly Monday as the
surface high moves east and a cold front approaches from the
Plains. Forecast soundings from the RAP and Canadian models look
best as far as mixing heights and surface dewpoints. That will
make for elevated fire weather conditions Monday afternoon and
early evening. Showers along the front will probably not arrive
until the evening hours.
A sharp upper trough will move across the area Tuesday. Cold
temperatures aloft will make for showers and thunderstorms. It
could be cold enough aloft for some graupel or snow showers in
the far north. A surface high and upper ridge will follow and
bring dry and cooler weather for Wednesday and Thursday. Milder
weather is expected Thursday as southerly flow returns ahead of
the next systems, which will bring showers and thunderstorms for
Friday.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1007 PM CDT Sat Apr 20 2024
Stratocumulus clouds should be east of the region by issuance
time, with only patchy mid/high clouds expected overnight. SCT-
BKN high-based cumulus clouds are expected to form during the
late morning and afternoon on Sunday, then dissipate in the
evening. Light west winds are anticipated overnight, with gusty
WNW winds picking up in the late morning and afternoon Sunday,
before diminishing again around sunset.
&&
.FIRE WEATHER...
Issued at 249 PM CDT Sat Apr 20 2024
Moderating temperatures and a dry airmass will lead to elevated
fire weather conditions on Sunday and Monday. Relative humidity
will be low (20-30 percent in the sandy soil regions) both days,
but winds look to be a little stronger on Monday.
Another period of elevated fire weather conditions is possible
next Wednesday and Thursday, as a dry airmass moves into the
region. Ensembles indicate PWATs are forecast to be 20-40% of
normal. Winds will likely be below critical levels due to the
proximity of the prevailing high pressure system.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....Uhlmann/RDM
AVIATION.......Kieckbusch
FIRE WEATHER...Kieckbusch
Area Forecast Discussion
National Weather Service Indianapolis IN
919 PM EDT Sat Apr 20 2024
.KEY MESSAGES...
- Becoming Mostly Cloudy tonight; Cold with Frost possible
- Partly Cloudy and warmer on Sunday
- Widespread frost possible Monday morning.
- Increasing rain chances Tuesday, low chance for thunderstorms
- Temperatures generally near seasonal next week, but brief cooldown
is possible Wednesday into Thursday
&&
.FORECAST UPDATE...
Issued at 918 PM EDT Sat Apr 20 2024
GOES-16 IR satellite imagery, obs and Hi-Res soundings support
raising cloud cover the rest of the evening especially. The increase
in cloud cover along with winds expected to stay up to 5 knots or so
should keep frost from being a big issue overnight. Raised overnight
lows a degree or two based on the more pessimistic cloud cover.
&&
.SHORT TERM (This evening through Sunday)...
Issued at 243 PM EDT Sat Apr 20 2024
Synopsis:
Surface analysis early this afternoon shows strong high pressure in
place over eastern Montana, Western SD and western NB. A surface
ridge extended southeast from the high, stretching across northern
MO to SW Indiana and Central KY. Cool northwest surface flow was in
place across Central Indiana, along with a moderate pressure
gradient. Dew points were in the dry mid 20s. GOES16 shows clear
skies in place across most of the forecast area. Some CU had
developed across northern Indiana, and some high cloud was blowing
off some convection over the southern plains, spilling into the Ohio
Valley. Aloft, a deep area of low pressure was found east of Hudson
Bay. This feature was providing a nearly zonal westerly flow in
place aloft across Indiana and water vapor imagery showed only
Pacific moisture aloft within that flow.
Tonight...
The mostly clear skies in place across Central Indiana today are
expected to be lost to cloudiness this evening and overnight. Models
suggest the upper flow becomes a bit southwesterly tonight. This
will allow for the advection of mid and high cloud from the Central
and southern plains to arrive across Central Indiana through the
overnight hours. Furthermore, a weak upper trough rotating around
the low is expected to push toward central Indiana providing some
lift well aloft. HRRR suggests the arrival of high clouds in this
manner, arriving this evening before exiting shortly after daybreak
on Sunday. Forecast soundings also trend toward high cloud
saturation with subsidence in place in the lower and middle levels.
Meanwhile at the surface the strong ridging is expected to remain in
place with cool air in place at the surface. Given our cool, dry air
mass, lows in the middle 30s will be expected overnight with light
winds.
This would be an ideal setup fro frost, but with the expected cloud
cover, frost may not form. Confidence on clouds is high, thus
confidence for frost is low. Hence will issue an SPS for isolated
frost overnight. Should the evening shift determine that the cloud
cover will not come to pass, a frost advisory will likely be needed.
Sunday...
The weak upper trough axis is suggested to arrive and pass across
Central Indiana on Sunday. This will quickly usher the mid and high
cloud out of central Indiana by late morning and early afternoon as
subsidence becomes predominate through the entire column. Again
forecast soundings show drying within the column, with some late
afternoon flat topped CU possible due to a mid level inversion when
convective temperatures are reached. The lower levels will remain
under the influence of the strong high pressure system over the
southern plains, along with an associated ridge axis stretching
across the Ohio Valley.
There is some slight warm air advection in place on Sunday
afternoon, thus slightly warmer highs in the middle 50s will be
expected.
&&
.LONG TERM (Sunday night through Saturday)...
Issued at 243 PM EDT Sat Apr 20 2024
Sunday night through Monday...
Quiet weather conditions will persist as surface high pressure and
upper ridging is centered near the central CONUS. Expect one more
cool night before warm air advection from the building ridge leads
to a warm up early next week. Lows dropping into the 30s Monday
morning combined with clear skies and light winds will likely lead
to widespread frost development. Expect surface high pressure to
then shift east on Monday allowing for return flow to warm
temperatures into the 60s.
Monday night onward...
Rain chances return Tuesday as a shortwave trough and associated low
pressure system move across the Great Lakes Region. Subsidence
induced dry air still present across the Mid-South may lend to limit
overall moisture return further north. Guidance shows a narrow
corridor of sufficient moisture return and increasing dynamics from
the approaching system to support rainfall. QPF amounts should
remain light due to a lack of deeper moisture, likely under half an
inch. Weak destabilization could also support a few PM
thunderstorms.
Expect the progressive pattern aloft to help push this system
further east by Tuesday night resulting in drier conditions
returning late. Cold air advection and surface high pressure
building in behind the departing low will allow for quiet weather
conditions to persist through much of Thursday before another
system approaches late next week. Temperatures falling into the
30s Thursday morning leads to some frost concern, though at this
time it appears winds may remain elevated enough to limit this
potential.
Models begin to diverge by late next week which limits forecast
confidence, but there is a general signal for an active pattern to
return. One thing to note, Indianapolis is already in the top 13
for wettest April`s on record. Numerous chances for rainfall
Tuesday, and then again late next week into the weekend will
likely push Indianapolis at least into the top 10 for wettest
April`s on record.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 642 PM EDT Sat Apr 20 2024
Impacts:
- None
Discussion:
Dew points in the 20s and dry boundary layer per Hi-Res soundings
lend high confidence to VFR flying conditions through the TAF
period. Only cloud cover will be a brief diurnal cu deck to start at
KLAF and mid and high clouds in the fast zonal flow aloft, ahead of
a northern Plains trough.
Winds will be northwest mostly less than 10 knots.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...MK
SHORT TERM...Puma
LONG TERM...Melo
AVIATION...MK
Area Forecast Discussion
National Weather Service North Platte NE
555 PM CDT Sat Apr 20 2024
.KEY MESSAGES...
- Tonight could be the last night of freezing weather for the
foreseeable future.
- A strong storm system continues to be predicted to affect wrn
and ncntl Nebraska Thursday and Friday. No severe weather
hazards expected across the region at this time.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 318 PM CDT Sat Apr 20 2024
The upper level disturbance affecting ern Colo/KS and swrn Nebraska
with snow is expected to exit Nebraska early this evening. This
timing is based a forecast blend using the HREF, HRRR, RAP and short
term model blend. Thereafter, there is evidence of dry air moving in
aloft and light winds near or below h850mb. The sfc high pressure
across the nrn high Plains this afternoon will settle across wrn
Nebraska by 12z Sunday morning. Patchy/areas of fog are in place
across swrn Nebraska and the srn Panhandle for the prospect of dry
air aloft and trapped moisture at the sfc.
Given the aggressive nature of the high Plains sfc high pressure
leading to widespread low temperatures in the 20s this morning, the
temperature forecast tonight leans toward the cooler guidance blend
and NBM 50th for lows in the 20s once again. The same strategy is in
place Sunday for full sun and warming temperatures. This suggested
highs in the upper 50s to lower 60s. The warmer short term model
blend is in place Sunday night for lows in the upper 30s to lower
40s. This forecast is based on strong warm air advection associated
with sfc low pressure circulating through the srn Canadian prairies.
The blended wind forecast using the short term blend plus the NBM
keeps winds up overnight and into Monday morning; the forecast
assumes no decoupling and very modest radiational cooling.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 318 PM CDT Sat Apr 20 2024
The next rain chance is with the arrival of a cold front
Monday night. The NAM and ECM support isolated to scattered showers
and thunderstorms, mainly across srn/cntl Nebraska. The focus is the
front and the forcing is an upper level disturbance dropping south
through the Dakotas for this event. Moisture transport could be
fleeting, directed toward ern Nebraska and WPC suggested no QPF for
this forecast. POPs are limited to 30 percent for these reasons.
The models are coming into better timing agreement for a strong
storm system progged to affect wrn/ncntl Nebraska Thursday and
Friday. Significant track differences remain ranging from SD in the
GEM to KS/ern Neb in the GFS. The ECM is in the middle favoring nwrn
and ncntl Nebraska. The sfc low could deepen below 990 mb in the GEM
and ECM. Chance/likely POPs are in place beginning as early as
Wednesday night when the region will be under the influence of
strengthening southwesterlies aloft and increasing moisture
advection at h850-700mb.
It is worth noting rain/thunderstorm chances Wednesday night through
Thursday night could be greatly limited by a strong cap, around 10C
at 700mb, as shown by the ECM. The GFS shows this cap weaker, cooler
than 10C. Regardless, both models show the cap weakening with wrap-
around rain Friday which could last into Saturday if the models
track the system slower.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 555 PM CDT Sat Apr 20 2024
VFR conditions expected at TAF sites through this valid period.
Satellite imagery shows a bloom of cumulus/stratocumulus north
of Hwy 2 that will gradually diminish with loss of daytime heating
and push off to the south. However radar shows some very light
SHRA/SHSN coincident with the main cloud shield south of Hwy 2.
There clouds are also moving southward and expect KLBF will
lose the CIG and become SCT this evening/early tonight with no
impacts from any light precipitation. There is a hint for some
fog across far southwest Nebraska late tonight, and while there
may be some valley fog right over the river do not expect
significant impacts on airfields so will not include with this
TAF issuance.
Winds will be light/variable tonight through Sunday morning.
Once diurnal heating mixes the boundary layer Sunday afternoon,
expect some gusts 20 to 25kt at KVTN but under 20kt at KLBF.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...MBS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
920 PM CDT Sat Apr 20 2024
.KEY MESSAGES...
- Freeze expected for areas west/southwest of Chicago late
tonight/early Sunday morning. Frost likely elsewhere outside
of Chicago.
- A period of inclement weather with periods of showers and
storms possible towards the end of next week into the weekend.
&&
.UPDATE...
Issued at 920 PM CDT Sat Apr 20 2024
Have elected to hoist a Frost Advisory for the remainder of the
CWA not already in the Freeze Warning, save for central Cook
County. Observational trends suggest that the overhead
stratocumulus deck should clear out over most of the area by
about 09-10Z, and recent HRRR runs have trended towards a little
more boundary layer decoupling occurring, at least in our
southern counties, which will be more closely positioned to the
center of an incoming region of surface high pressure. Thus,
confidence has increased enough in widespread frost developing
in Ford, Iroquois, Kankakee, and southern Will counties to
warrant the issuance of a Frost Advisory there.
Farther to the north, some uncertainty remains regarding whether
boundary layer decoupling will remain more limited, thus
permitting at least occasional mechanical mixing into 10-15 kt
flow atop the stabilizing boundary layer, which would tend to
inhibit frost development. While the stratocumulus should clear
out of there within the next 5-6 hours, the coverage and overall
influence of some incoming high-level cloud cover remains somewhat
uncertain, and it is possible that this also will end up being
a limiting factor for frost development closer to the Illinois-
Wisconsin state line. Our northwest Indiana counties will be
dealing with these same wind and cloud cover-related
uncertainties, plus the possibility that the lower stratocumulus
clouds don`t depart in time for efficient radiational cooling
to begin until just before dawn.
In spite of these lingering uncertainties, opted to err on the
side of caution and issue the Frost Advisory through pretty
much the remainder of our CWA, as at least patchy frost will
still probably develop in our wind- and cloud-beleaguered
counties with temperatures still likely to fall into at least
the mid 30s there overnight. The lone forecast zone that was
left out of the Frost Advisory was central Cook County, with the
expectation that the influence of the urban heat island effect
will keep temperatures there just "warm" enough to preclude the
development of widespread frost.
Ogorek
&&
.DISCUSSION...
Issued at 231 PM CDT Sat Apr 20 2024
Through Sunday night:
Northern IL/northwest IN remain within the southern periphery
of a deep upper trough over eastern Canada. Breezy west-
northwest flow was maintaining cold advection, with steep low-
level lapse rates helping to produce a dense, widespread
stratocu deck across the area this afternoon. Daytime
temperatures have struggled in the face of this cold advection
and opaque cloud cover, with readings only in the low-mid 40s
across most of the cwa as of 2 pm. Clouds are expected to
persist in this evening, though some thinning is likely with
time as we lose the diurnal component. Timing of trailing edge
over the upper Mississippi Valley per satellite imagery suggest
clearing from the northwest by mid-evening for our northwest
counties, and eventually around/a bit after midnight farther to
the east (perhaps a bit earlier with the loss of diurnal low-
level instability).
Clearing, continued low-level cold advection and a weaker
surface pressure gradient (and resulting winds) than last night
suggest we`ll likely have freezing temperatures across the
western half or so of the cwa by morning. In collaboration with
MKX/DVN and ILX have elected to issue a Freeze warning for areas
west and southwest of Chicago, where conditions appear most
favorable. Farther east, will likely see some areas of frost
toward morning, though air temperatures are expected to remain
above freezing. Had contemplated a frost advisory, though
lingering 10-15 kt flow above the boundary layer and slightly
warmer temperatures lend lower confidence to longer duration
widespread frost conditions. Better frost potential looks to be
across central IL, where winds will be lighter in closer
proximity to the surface ridge axis.
Sunny skies are expected for Sunday, with weak mid-level
ridging developing in the wake of an early morning positive-tilt
mid-level short wave. Guidance depicts 50-60 meter mid-level
height rises within deep subsidence behind this wave, with the
pocket of coolest mid-level air also moving off to the east of
the region. Under sunshine (perhaps just a shallow fair-weather
cu field), temps should "rebound" to the upper 50s/around 60
degrees for afternoon highs. We`ll still be a bit breezy, north
of the surface ridge, with west-northwest winds gusting around
20 mph during the day. Winds diminish and back west-southwest
Sunday night under clear skies. Could see some patchy areas of
frost away from the city again toward Monday morning, though
overnight lows are expected to be a bit warmer ranging from the
mid-30s to around 40 in Chicago as warm advection begins to
strengthen aloft.
Ratzer
Monday through Saturday:
Increasing low-level southwest flow behind a departing ridge
combined with strong diurnal mixing into a rather dry layer
above the PBL will support the potential of brush fire spread
Monday afternoon. Afternoon fine fuel moisture values are
already below 10% this afternoon, so with additional drying the
next couple days, current forecast RH values as low as 25-30%
and wind gusts possibly over 20 mph, we will continue to message
elevated fire wx concerns.
Strong upper-level diffluence ahead of a zonal jet streak over
the northern Great Plains will promote decent mid-level ascent
over an antecedent dry airmass. Modest mid-level lapse rates
around 7.5C/km should foster scattered high-based showers or
even a storm or two late Monday night. The surface low
associated with the upper jet streak and concomitant mid-level
trough/low will push a surface front across the CWA sometime
Tuesday afternoon. Deep mixing and marginally favorable low-
level moisture profiles should support diurnally driven showers
and some thunderstorms along/ahead of the front. More aggressive
guidance even suggests the potential for small hail given
freezing levels as low as 6kft and steep lapse rates into the
hail growth zone below EL values around 20kft.
In the wake of Tuesday`s system, a ~1030hPa high will settle
southeastward across the Great Lakes region Wednesday through
Thursday. With another dry and cool airmass in place during this
period and the southwest extent of the high edging into the
forecast area, widespread frost conditions and/or sub-freezing
temperatures are possible Wednesday night.
A highly amplified mid-level pattern Friday into next week will
bring another period of active weather to the central portion
of the CONUS. While consensus guidance favors keeping a
seasonably strong low well northwest of the forecast area,
several members (including the deterministic GFS) are
precariously close enough to warrant close monitoring of trends
for stronger convection in our area late Friday.
Kluber
&&
.AVIATION /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 627 PM CDT Sat Apr 20 2024
There are no significant aviation forecast concerns for the
current TAF period. The overhead VFR stratocumulus deck is
expected to disperse later tonight, yielding clear to mostly
clear skies for tomorrow. Winds should remain out of the west
or west-northwest throughout the TAF period while staying near
or under 10 kts throughout this time, though some gusts closer
to 20 kts are possible at times tomorrow afternoon. A lake
breeze may also affect GYY tomorrow afternoon, but confidence
in this occurring is currently too low to warrant adding a new
line to the GYY TAF for that with this issuance.
Ogorek
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Freeze Warning from 3 AM to 8 AM CDT Sunday for ILZ003-ILZ004-
ILZ005-ILZ008-ILZ010-ILZ011-ILZ012-ILZ019-ILZ020-ILZ021-
ILZ032.
Frost Advisory from 3 AM to 8 AM CDT Sunday for ILZ006-ILZ013-
ILZ023-ILZ033-ILZ039-ILZ103-ILZ105-ILZ106-ILZ107-ILZ108.
IN...Frost Advisory from 3 AM CDT /4 AM EDT/ to 8 AM CDT /9 AM EDT/
Sunday for INZ001-INZ002-INZ010-INZ011-INZ019.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Memphis TN
946 PM CDT Sat Apr 20 2024
...New UPDATE...
.UPDATE...
Issued at 937 PM CDT Sat Apr 20 2024
Minor adjustments were made to overnight PoPs as this first round
of rain comes to a close. As another weak shortwave trough moves
through the area, a second round of showers is expected to surge
up through the ArkLaMiss overnight tonight. Moisture nor
instability look sufficient enough to produce anything but light
scattered showers through sunrise with less than a tenth of an
inch of QPF. Once the sun rises tomorrow, dry conditions will
return and remain in place for much of the week.
&&
.SYNOPSIS...
Issued at 140 PM CDT Sat Apr 20 2024
Cool temperatures are the biggest story weather-wise over the
next seven days. Monday should be the coolest morning featuring
low temperatures in the middle 30s to low 40s. Frost is possible
in portions of west Tennessee, mainly near the Tennessee River.
Otherwise, gradual warming is expected tomorrow(Sunday) afternoon
through Midweek along with gradually warming temperatures. High
temperatures should approach 80 degrees by Friday.
&&
.DISCUSSION...
(This evening through next Friday)
Issued at 140 PM CDT Sat Apr 20 2024
Zonal flow is in place across the middle and lower Mississippi
River Valley. Weak impulses moving through the westerly flow will
result in another round of elevated showers and possibly a few
thunderstorms this afternoon, mainly in north Mississippi. The
HRRR is a bit of an outlier shifting most of the precip into
Alabama well before midnight. That may be a bit optimistic based
on current radar. Showers and thunderstorms stretch as far west as
the Texas Panhandle. However, high pressure should build into the
Midsouth from the northwest tonight and should shift the storm
track farther south. Confidence is higher that rain will continue
through much of the night, shifting out of the region before
sunrise. Sunday should be mostly dry, especially after midday with
dry conditions continuing through midweek.
Cool conditions are expected tonight and Monday morning with frost
possible near the Tennessee River Monday morning. Most of the
Midsouth will be in the middle to upper 30s. High temperatures
should be in the low to middle 60s tomorrow and in the middle to
upper 60s Monday.
A positively tilted trough will swing across the Mississippi River
Valley early Monday and surface high pressure should shift east of
the area Monday afternoon. This will mark the beginning of a
gradual warming trend next week. High temperatures should be in
the middle 70s by Wednesday and near 80 degrees by Friday.
A ridge will build over the eastern Rockies and Plains after
midweek setting up northwest flow across the Midsouth. However,
guidance is in poor agreement during this time frame. For now we
will carry low pops Thursday into Friday and and see how things
develop in subsequent model runs before increasing or removing
PoPs late in the work week.
30/Sirmon
&&
.AVIATION...
(00Z TAFS)
Issued at 636 PM CDT Sat Apr 20 2024
An area of rain will push across TUP over the next couple of hours
otrw VFR conds will prevail throughout the period. A few more
SHRAs are possible south of I-40 later tonight but aviation
impacts will be limited. NNE winds at 8-10 kts will increase to
10-14 kts early Sunday morning with gusts 16-22 kts.
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...JDS
AVIATION...SJM