Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/01/20

Area Forecast Discussion

National Weather Service Grand Forks ND

 939 PM CDT Thu Apr 30 2020

.UPDATE...
Issued at 939 PM CDT Thu Apr 30 2020

Area of potential rain showers still moving into eastern North
Dakota and northwest Minnesota, but with no reports of rain
reaching the surface chances seem very low for much accumulation.
Right now with a dry layer near the surface only drizzle or some
light rain might make a through for a short period tonight.

UPDATE Issued at 657 PM CDT Thu Apr 30 2020

There has been reflectivity across parts of the northern North
Dakota this evening, but with the lower levels of the atmosphere
being dry nothing has been reaching the surface. CAM guidance
continues to show the activity in MB moving down into ND and MN
later this evening and overnight. Based on up stream reports this
should be no more than drizzle or light showers. The main event is
still expected to be tomorrow afternoon and evening.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 310 PM CDT Thu Apr 30 2020

We can expect mainly dry conditions through the late afternoon
and early evening periods. A warm frontal arc is moving up and
across the area attm, with more of a triple point setting up into
southwest MB. Some thin upper level clouds are showing into
northeast ND and far northwest MN now, with patches of mid cloud
evident in northcentral ND. Else, the 17z HRRR runs are lining up
well with the 12z NAM... and showing scattered showers and an
isolated thunderstorm developing into south-central MB this
evening and dropping southeastward into far northwest MN in the
late evening and overnight period. The 18z NAM is a bit less
robust on this feature. Again, dry air will limit overall
convection there, tonight.

Friday will see a bit of a squeeze play between the lingering
warm frontal boundary across northwest MN and an approaching cold
frontal boundary through northeast ND... giving highest potential
for measurable rainfall and tstm activity at the west,north, and
eastern edges of our CWA. Overall airmass conditions should be
fairly dry, so not expecting much for total precipitation. SPC
keeps us in a general thunderstorm area for this DY2 period. Note
that at this writing, WPC is looking to adjust their DY2/3 QPF
expectations based on the 12z ECMWF data. This would line up
a bit better with the previously wetter 12z GFS and NAM solutions
over northcentral MN. The current temperature pattern has been
well handled by the main models, and continues some 5 degrees or
more above seasonal normals for through this period.

.LONG TERM...(Saturday through Thursday)
Issued at 310 PM CDT Thu Apr 30 2020

Some active weather is likely to skip the weekend over the forecast
area and wait for the beginning of next week. This will come in the
form of a lengthier period along with cooler temps.

In the wake of departing boundary, Sat should shape up dry, breezy,
and seasonal with highs in the 60s. Any activity Sun will likely
remain south but a deeper wave/upper low will challenge the region
early next week. This will entail an extended showery period from
sometime on Mon through Tue with a few embedded thunderstorms
(although CAPE is not very apparent this far out), and unreasonably
low daytime temps only in the 50s that will persist through most of
the week. Weak high pressure Wed will be followed by the next system
advancing on Thu.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 657 PM CDT Thu Apr 30 2020

VFR conditions prevails tonight into tomorrow morning. Tomorrow
scattered showers and isolated thunderstorms are possible at all
terminals. This could lead to a period of MVFR in showers and IFR
in thunderstorms. The highest chance for thunderstorms will be
along a cold or occluded front in the afternoon and evening on
Friday.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.

River point flood warnings continue across portions of
the region. Refer to the latest flood warnings and statements for
detailed information on specific locations.

&&
$$

UPDATE...NC
SHORT TERM...Gust
LONG TERM...WJB
AVIATION...NC




Area Forecast Discussion

National Weather Service Wilmington NC

 914 PM EDT Thu Apr 30 2020

.SYNOPSIS...
A cool and dry air mass will move in for Friday as high
pressure builds across the region. The high will dominate this
upcoming weekend, resulting in a warming trend across the area.
A cold front will drop south into the Carolinas later Monday
and may linger near or just south through mid-week.

&&

.UPDATE...
Shallow convective showers have developed due to steep lapse
rates and residual low-level moisture. A few of these are
actually dropping some briefly heavy rain across Columbus and
Bladen counties. This activity is moving east-northeast at 30
mph and should be out of the area before midnight. Relatively
light winds across the coastal waters currently should increase
substantially around midnight, therefore I`ll maintain the Small
Craft Advisory. Other changes to the forecast were minor and
include tweaks to temps and sky cover based mainly on the latest
HRRR model.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
Rain and isolated thunderstorms along an approaching cold front
continues across the forecast area through this afternoon. As
of the early afternoon, the cold front based on surface observed
wind fields showed the front aligned along the I-95 corridor
and moving eastward. Moderate to heavy rain showers continued
mainly for locations along the NC coastal counties, although
widespread light rain for most of the region. Latest model
guidance has rain exiting offshore by late afternoon with some
scattered light rain possible into the evening and into Friday.
The upper level trough disturbance is still lingering behind the
surface cold front, which will keep light scattered rain for
the next 36 hours at times across the area. Breezy conditions
will subside somewhat heading into Friday, but gusts as high as
25 mph are still possible until high pressure reaches the region
for the weekend.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Elongated surface high centered west of the area Sat morning will be
slowly shifted southeast by northwest flow aloft. The resulting warm
advection developing late Sat and Sat night will raise temps from
near climo Sat to above climo Sun/Sun night. Skies will be mostly
clear for much of the weekend with clouds starting to increase late
Sun/Sun night as moisture aloft moves in from the northwest.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Next week`s main feature will be a cold front dropping in from the
north Mon night which then lingers in the area until late Wed or
early Thu. A series of weak waves will move east along the stalled
boundary, with the strongest passing in the vicinity during Wed.
Hard to pin down exact location of the front and the waves this far
in advance. West to northwest flow aloft will limit moisture, but
each wave will have at least some potential to develop light showers
across the area. Exit of strongest wave Wed night helps push the
front well southeast of the area early Thu with high pressure
building in behind the front. Temperatures a little above climo
Mon/Mon night run near climo Tue through Wed night then fall a
little below climo Thu.

- Potential for showers Mon through Wed night with Wed/Wed
  night looking most favorable.

- Temperatures above climo Mon/Mon night, will run near climo
  Tue through Wed night then dip a little below climo Thu.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR conditions will continue for the next 24 hours. Periods of
cumulus clouds with bases around 5000 feet AGL are expected this
evening and again Friday. Depth could be sufficient for some
sprinkles or showers at times, although coverage will be
limited. West winds could gust to near 20 knots Friday.

Extended Outlook...VFR through the weekend. A front stalled in
the area Monday and Tuesday could lead to MVFR ceilings and
showers.

&&

.MARINE...
Westerly winds for the next 36 hours between 10 and 20 kts and
gusting to 25 to 30 kts at times with waves from the SSE 5 to 9 feet
tonight at 8 to 10 seconds diminishing to 4 to 6 feet at 8 to 10
seconds Friday into Friday night.  Smaller vessels and inexperienced
mariners may encounter hazardous conditions over the coastal waters
out to 20 NM.

Offshore flow Sat will become southwest Sat night as winds back in
response to surface high shifting offshore. Winds will remain light
through Sat night before gradient becomes more defined and southwest
flow starts increasing. Southwest flow briefly approaches 20 kt late
Sun or Sun night before cold front moving in from the north-
northwest helps relax the gradient. The front reaches the waters
later Mon or Mon night before stalling in the area Tue. Seas will
run 3 to 4 ft for much of the period with brief potential for 5 ft
seas Sun night into Mon as southwest flow ramps up. Offshore flow
Sat will develop a weak westerly wind wave on top of a weak
southeast swell. The westerly wind wave is quickly replaced by a
southwest wind wave Sun through Tue with the southeast swell
lingering into the middle of next week.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 8 AM EDT Friday for AMZ254-256.
     Small Craft Advisory until 10 PM EDT Friday for AMZ250-252.

&&

$$

SYNOPSIS...III
UPDATE...TRA
NEAR TERM...MCK
SHORT TERM...III
LONG TERM...III
AVIATION...TRA
MARINE...MCK




Area Forecast Discussion

National Weather Service Indianapolis IN

 1148 PM EDT Thu Apr 30 2020

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 237 PM EDT Thu Apr 30 2020

High pressure will build in and bring dry weather for Friday. A
frontal system will bring rain chances to the area for the
weekend, then another system will bring more rain next week.
Temperatures will be near to above normal into early next week,
then below normal readings will return.

&&

.NEAR TERM /Rest of Tonight/...

Issued at 1002 PM EDT Thu Apr 30 2020

Rest of Tonight...
Removed mention of any lingering rain showers early tonight.

Previous Discussion...
Wrap around moisture associated with upper and surface lows to the
east will linger across central Indiana into tonight. Scattered
showers will continue this afternoon, then diminish from west to
east during the evening. Went a little more pessimistic than the
HRRR on ending the rain as other models are hinting at a longer
wait thanks to some lingering forcing.

Clouds will then slowly decrease from west to east, but the
clearing will slow or stop across the eastern forecast area
overnight as more moisture rotates in. Will keep skies partly to
mostly cloudy across the east half later tonight through Friday
morning with lower cloud amounts west.

Some increase in higher clouds will occur Friday afternoon ahead
of the next system.

With fewer clouds and lighter winds tonight, the western forecast
area could get into the upper 30s. The NBM looks reasonable for
low temperatures. For highs Friday, raised the NBM a bit with some
decent warm advection occurring.

&&

.SHORT TERM /Friday Night through Sunday/...
Issued at 338 PM EDT Thu Apr 30 2020

Will introduce measurable precipitation into the forecast
beginning Saturday night as a frontal boundary sinks into the
region and subtle upper level waves begin to move along it. Cannot
totally rule out some sprinkles or drizzle during the day on
Saturday with profiles moist in the low levels and some weak lift
present, but prefer to keep non measurable precip out of the
forecast at such time lengths. Did bump up cloud cover over what
blend provided.

Pops will gradually increase into Sunday afternoon, when the Euro
is quite bullish on a slug of precip moving through the area along
the boundary. GFS is further southward with the boundary and drier
for this area, but there`s some indication that feedback issues
may be tainting the GFS output.

Temps will be above normal through the weekend with highs in the
70s likely both days.

&&

.LONG TERM /Sunday Night through Thursday/...
Issued at 338 PM EDT Thu Apr 30 2020

Tail end of the precip chances associated with the previously
mentioned boundary will bleed into Sunday night, with a brief
break before a more substantial low pressure system, and then a
weaker trailing wave, move through the area late Monday night into
Wednesday in the relatively fast quasi-zonal/becoming slightly
northwest flow aloft.

Temperatures will be a bit cooler during the long term but still
fairly pleasant, with highs retreating back into the 60s for the
most part.

&&

.AVIATION /Discussion for the 01/06Z TAF Issuance/...

Issued at 1143 PM EDT Thu Apr 30 2020

VFR is prevailing at all TAF sites and will remain the predominant
flight category for the duration of the TAF period as high
pressure strengthens over the region. In addition, winds have
tapered off and are now northwesterly at 5 to 10 kts. They will
become light and variable through the course of the TAF period.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...50
NEAR TERM...50/TDUD
SHORT TERM...Nield
LONG TERM...Nield
AVIATION...TDUD



Area Forecast Discussion

National Weather Service Key West FL

 1017 PM EDT Thu Apr 30 2020

.DISCUSSION...
After an active mid to late afternoon across the Florida Keys and
surrounding coastal waters, with thunderstorms producing strong
wind gusts as high as 48 mph at Cudjoe Key, quiet weather has
returned to the area this evening. Leftover outflow from earlier
convection over the Straits has backed surface winds to SW along
the Keys, but this will be short-lived, as satellite and radar
data show the wind shift associated with the approaching cold
front over the Gulf waters about 40 miles northwest of Key West
as of 10 PM. Surface analysis shows the front extending from the
Mid Atlantic coast across extreme South Florida and into the far
southeastern Gulf of Mexico. This unusually late season front is
being driven through the Keys by a strong and deep closed low,
which water vapor imagery shows centered over Ohio and anchoring a
sharp trough over the eastern CONUS. Ahead of this front,
temperatures along the Keys remain in the mid to upper 70s, with
dewpoints still in the lower 70s.

Overnight, expect the front to push through the Keys during the
next few hours, reaching Key West before midnight and clearing the
Upper Keys by around 2 AM. Recent radar data shows scattered
showers developing over the Gulf waters and around the Lower Keys
just ahead of the front, and some CAM guidance including the HRRR
and the experimental HRRR-Caribbean does bring this shower
activity through the Keys during the night. Have retained slight
chance of showers wording for the overnight period. Although
temperatures will not drop much behind the front, with lows by
morning only reaching the mid 70s, a significantly drier airmass
will move into the Keys late tonight, and expect dewpoints to be
well down into the 60s by sunrise.

&&

.MARINE...
Leftover outflow from earlier convection over the Straits backed
winds to SW across the Keys waters, but this will not last long,
as the cold front is currently approaching the Lower Keys and will
move through the Keys and into the Straits during the next few
hours. Expect fresh NNW breezes behind the front. Have posted
Small Craft Exercise Caution headlines for all zones overnight
with the late evening forecast update, as the WRF-ARW model, which
often handles post-frontal northerly flow the best, shows a
period of 15 to 20 knot winds between midnight and sunrise.

&&

.AVIATION...
Short periods of MVFR ceilings and perhaps even a brief shower
will be possible at the EYW and MTH terminals through the midnight
and late night hours, as a cold front passes through the Keys.
Winds will shift to the NNW and increase to 10 to 15 knots with
gusts up to 20 knots after the front moves through. Expect
clearing skies Friday morning, with high confidence in VFR
conditions through the day, and northerly breezes around 10 knots.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&

$$

Public/Marine/Fire...Jacobson
Aviation/Nowcasts....Jacobson
Data Collection......KBL

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Area Forecast Discussion

National Weather Service Riverton WY

 206 PM MDT Thu Apr 30 2020

.SHORT TERM...(This evening through Friday night)
Issued at 206 PM MDT Thu Apr 30 2020

With the ridge axis now to our east, and the steering flow slightly
difluent from the west southwest, scattered thunderstorms are
getting underway, mainly in the west and north. There has been
plenty of time since the morning round of showers for the solar
insulation to heat us up to the convection temperatures. Lifted
indices are now down to minus 2 in the southwest and northwest with
the best cape of 520 J/KG over South Pass. The strongest
thunderstorm at the time of this writing so far has tracked east
across the vcnty of Pinedale. The best combination of RH and
instability will continue to be over the northwest this afternoon
and evening. The HRRR insists on pulling the convection to area east
of the Divide this afternoon, but with drier air to the east, the
major threats will shift from small hail and gusty winds in the
west, to stronger outflow winds and not as much precip east where
temp/dew point spreads are greater. With the rapid movement of these
cells, all cells will deliver gusty winds due to the mid and upper
level winds being translated to the surface with the outflow winds.
With freezing levels around 13K, small hail will be likely with most
of these cells. This convection will continue trough the evening
until about 07Z before exiting northeast into Montana.

On Friday, most of the convective activity will be over the southern
half of the CWA, as well as over the eastern zones, closer to the
track of a vort max that will track east northeast across southern
and east central Wyoming. During the past few days, the models have
been insisting on much heavier rain over southeast Wyoming. Casper
will likely get grazed by this best convection. Lifted indices of
minus 2 are expected. Scattered thunderstorms could persist through
the night in southeast Sweetwater and southeast Natrona County
Saturday night.

Not much fluctuation in temperatures are expected.

.LONG TERM...(Saturday through Thursday)
Issued at 206 PM MDT Thu Apr 30 2020

Saturday looks mainly dry with isolated late day showers or storms
in the west. This activity will occur in the west Saturday night as
well. Sunday will see scattered showers and thunderstorms over most
of the region in the afternoon into the evening hours due to a
weather disturbance that moves through the region. Would expect
isolated showers to persist through the late night hours of Sunday.
On Monday, a stronger weather system in the southwest flow aloft
moves through the area. This results in showers and thunderstorms
over the region Monday into Monday evening, more numerous in the
north half than the south half. Snow levels will be lowering Monday
as colder air moves in, but not expecting much impact at the lower
elevations of NW WY. Tuesday is still looking dry with high
pressure. The next weather system will move into the region on
Wednesday with a chance of showers and thunderstorms to many areas.
Next Thursday looks unsettled with scattered showers and
thunderstorms yet again. High temperatures Saturday and Sunday will
be in the 60s and 70s with some 50s in the far west. Cooler Monday
with 50s and 60s for highs with some 40s in the far west. Then
milder Tuesday through Thursday with 60s to lower 70s for highs.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued
at 206 PM MDT Thu Apr 30 2020

Scattered showers and thunderstorms will occur over the west through
03Z, then decrease to isolated showers and end by 06Z. Some storms
will have small hail and wind gusts to 35 knots.

Along and east of the divide, scattered showers and storms will
occur through 04Z, then isolated showers until 06Z. Some storms will
produce wind gusts to 40 knots and small hail.

Brief MVFR/IFR will occur in convection.  Otherwise, VFR conditions
will prevail at the terminal sites. The exception could be some fog
late tonight in the far western valleys and have added VCFG at
KJAC for now.

On Friday, scattered showers and thunderstorms will occur after 19Z
in southern WY with isolated activity elsewhere.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC
for the latest information on icing and turbulence forecasts.

&&

.FIRE WEATHER...
Issued AT 206 PM MDT Thu Apr 30 2020

A weather system will cross the state this afternoon and produce
showers and thunderstorms, which will be most numerous across
western and northwest Wyoming through this evening. Some storms
could become strong, with hail and strong winds, again especially
over western portions. Breezy to windy conditions will develop
ahead of the front. Relative humidity should remain above critical
levels. Mixing and smoke dispersal will range from poor across
some of the northern basins to good to excellent across much of
central and southern Wyoming. Another round of afternoon and
evening thunderstorms are expected Friday, with the best coverage
over southern and southeast Wyoming. Some of the storms in eastern
zone 279, 280, and 300 could persist through the night Saturday
night. The most substantial rainfall could fall in these zones as
well.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Lipson
LONG TERM...Ross
AVIATION...Ross
FIRE WEATHER...Lipson