Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
250 PM EDT Fri Jun 24 2022

Valid 00Z Sat Jun 25 2022 - 00Z Mon Jun 27 2022

...Severe thunderstorms and flash flooding possible for parts of the
northern Plains and Upper Midwest through tonight...

...Monsoonal moisture and an approaching cold front to create the threat
of heavy rain and instances of flash flooding over portions of the
Southwest and southern Rockies through this weekend...

...Stifling heat persists across the South while temperatures also climb
for much of the Pacific Northwest...

A potent upper-level trough over the northern Rockies and an associated
cold front advancing southeast will set the stage for numerous rounds of
showers and thunderstorms across the northern Plains and Upper Mississippi
Valley going through tonight into early Saturday. An anomalously warm and
moist airmass ahead of the approaching front will lead to conditions
favorable for thunderstorms to turn severe. The Storm Prediction Center
has maintained an Enhanced Risk (level 3/5) of severe thunderstorms for
eastern North Dakota, northeastern South Dakota, and northwestern
Minnesota. Damaging wind gusts, very large hail, and a couple of tornadoes
are possible, with the potential for severe thunderstorms extending
southward to Nebraska and western Iowa as well. Along with the severe
potential, heavy rain may lead to some flash flooding from eastern North
Dakota to northern Minnesota. A Slight Risk (level 2/4) of excessive
rainfall has been issued to highlight this concern.

Meanwhile, monsoonal moisture will remain in place throughout the
Southwest and into the southern/central Rockies through this weekend. This
will lead to continuing chances for scattered thunderstorms and at least
an isolated threat of flash flooding. By Saturday, a cold front is still
expected to approach and should focus more organized convection from
northern New Mexico to southwest Kansas. These thunderstorms may be
slow-moving and will be capable of producing heavy rainfall amounts. Some
of the burn scar locations in the Sangre De Cristo range of south-central
Colorado and northern Mew Mexico will be particularly vulnerable to runoff
concerns and flash flooding due to this heavy rainfall potential. A Slight
Risk of excessive rainfall has been issued for these regions on both
Saturday and Sunday. Elsewhere, chances for scattered showers and
thunderstorms will continue across the eastern Gulf Coast, Southeast, and
Florida through this weekend.

Dangerous heat will remain a concern over much of the South through this
weekend. High temperatures underneath a stagnant upper-level ridge will
soar into the upper-90s and low 100s from the southern Plains to the
eastern Gulf Coast. Heat Advisories have been issued from central Texas to
the western Florida Peninsula as heat indices potentially approach 115
degrees through this evening. Excessive Heat Warnings are posted for parts
of Louisiana, including New Orleans, as well as southern Mississippi and
the Big Bend of Florida. Slightly cooler air will enter parts of the
Southeast and Florida on Saturday as easterly winds off of the western
Atlantic offer some relief. However, sweltering heat is forecast to
continue across the Southern Plains and Lower Mississippi Valley while
potentially threatening a few daily high temperature records. Farther
north, above average temperatures with highs into the upper-90s will reach
into the mid-Mississippi Valley on Saturday ahead of the approaching
upstream cold front, with low 90s making it into the northern Appalachians
on Sunday. For the Pacific Northwest, summer is finally making an
appearance and could bring with it dangerous heat. Highs are forecast to
climb each day through Sunday and reach into the 90s across much of the
region, with 100s farther south into the central valley region of
California. Heat Advisories have been issued for western portions of
Washington and Oregon for Saturday and Sunday.

Snell/Orrison

Graphics are available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
306 PM EDT Fri Jun 24 2022

Valid 12Z Mon Jun 27 2022 - 12Z Fri Jul 01 2022

...Overview...

Guidance still agrees that a broad upper level ridge over the
southern half of the CONUS will be in place through much of the
medium range period, forcing storm tracks mainly through the
northern tier. A vigorous shortwave through the Upper
Midwest/Great Lakes will amplify some as it moves into the
Mid-Atlantic and the Northeast early next week, pushing a surface
cold front across the East and helping produce showers and
thunderstorms. Behind this, amplified ridging should build over
the Northwest U.S., and slide into the northern Plains as a closed
low/upper trough could settle over the Pacific Northwest, perhaps
by around Wednesday. Meanwhile, monsoonal moisture will continue
to persist into the Four Corners region through much of the
period, with the best potential for heavier to excessive rains to
remain across the south-central Rockies into early next week.


...Guidance Evaluation/Predictability Assessment...

Recent model guidance remains in good agreement through the medium
range time frame for the large scale pattern described above and
its evolution. This includes a couple of rounds of troughing over
the northeastern U.S. and ridging shifting from the northwestern
to north-central U.S. behind. Some slightly larger differences are
indicated in model guidance with the track of an eastern Pacific
upper low that should shift into southwestern Canada/northwestern
U.S. around Wednesday, and CMC runs have been most consistent in
leaving energy farther west. Then there are some placement
differences with the centroid of a central Canada/Hudson Bay upper
low, with the GFS on the western side Wednesday-Friday, which
could cause minor differences over the northern U.S. with
troughing and surface frontal placement. But the overall good
agreement allowed for the updated WPC forecast to use a
multi-model deterministic blend of the 00/06Z GFS runs and 00Z
ECMWF, CMC, and UKMET, phasing in the 00Z EC ensemble mean in
place of the UKMET by days 6-7, but with a majority deterministic
blend. This created a middle ground solution with decent
continuity from the previous issuance.


...Sensible Weather/Threat Highlights...

Anomalously high monsoonal moisture for this time of year, likely
tied at least in part to Tropical Storm Celia in the East Pacific,
will continue streaming into the Four Corners states into early
next week. Locally heavy to excessive rainfall will be possible
each day, particularly over sensitive burn scar areas and
considering the multiple day repeating nature of this activity.
The best chance for impactful rainfall looks to be over parts of
southern Colorado/New Mexico with favorable upslope flow
interacting with the moisture already in place. A Slight Risk was
maintained across northern New Mexico on the experimental day 4
excessive rainfall outlook for Monday where good model agreement
overlapped with areas that have seen anomalous rainfall already.
Activity then wanes around Tuesday-Wednesday, but there may be
another uptick in moisture by the latter part of next week.

A cold front should be fairly progressive through the East Monday,
but should focus enough moisture and instability to fuel
convection with possibly locally heavy rainfall. A settling of the
front across the Gulf Coast, as well as the next cold front
dropping into the region, should allow for enhanced rainfall into
the middle of next week from Florida to along the Gulf Coast as
aided by protracted onshore fetch of moisture. Elsewhere,
progressive fronts tracking across the Upper Midwest into the
Upper Great Lakes should produce a couple of rounds of rain and
storms through the workweek there, and rain may also focus over
the central Plains/Mid-Mississippi Valley by late week as a front
shifts into that area.

By early next week, temperatures all across the South should
finally trend back towards normal. Relatively cooler temperatures
with well below normal highs are likely to be most persistent over
parts of New Mexico and Colorado given the monsoonal clouds and
rain coverage. In the West, ridging through the region should
present an excessive heat threat across parts of especially the
Northwest into Monday with the above normal temperatures then
working through the northern half of the Rockies, Plains, Midwest
and then East Tuesday-next Friday as we head into July.


Tate/Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Heavy rain across portions of the Southern Rockies, the Central
Rockies, the Southern Plains, the Central Plains, and the
Southwest, Mon, Jun 27.
- Flooding occurring or imminent across portions of the Upper
Mississippi Valley, the Northern Plains, and the Northern Rockies.
- Excessive heat across portions of California, the Central Great
Basin, the Pacific Northwest, the Northern Great Basin, and the
Southern Plains, Mon, Jun 27.


WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, experimental excessive rainfall
outlook, winter weather outlook probabilities and heat indices are
at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
303 AM EDT Fri Jun 24 2022

Valid 00Z Sat Jun 25 2022 - 00Z Sat Jul 02 2022

Models and ensembles reasonably agree that trade winds should be
light through the weekend as supporting surface pressure gradients
weaken under a weakness aloft. This could allow a few locally
enhanced showers. High pressure should again build back in to the
north and east of the islands by early next week, suggesting a
return of moderate to breezy trade winds. Overall, expect a
generally dry pattern for Hawaii for much of next week with
limited chances for typical windward/mountain showers. By later
next week, some enhanced moisture may move towards the state, with
possible residual connection to Celia.

Schichtel

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1138 AM EDT Fri Jun 24 2022

Day 1
Valid 12Z Fri Jun 24 2022 - 12Z Sat Jun 25 2022

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL MAINLY FROM
EASTERN NORTH DAKOTA INTO NORTH-CENTRAL MINNESOTA...

16z update:

...Northern Plains/Upper Mississippi & Midwest...
Ongoing convective complex ongoing across N MO has continues to be
progressive with some isolated stronger downdraft cores with heavy
rainfall; however, they have been just below and are expected to
be below FFG values in all but widely scattered cases near urban
centers. Stronger ridging builds into the area with rising
mid-level capping WAA to likely suppress mid-afternoon/evening
development. As such have carved back the Marginal Risk through
to Central IA where 12z Hi-Res CAMs suggest stronger clusters/weak
MCS to develop later this evening/overnight. There are some solid
QPF signals of 3-4+" to suggest a Slight Risk could be supported
but there remains enough latitudinal spread to be confident enough
to paint an area. Further north, stronger forcing and expected
convective coverage with intense rainfall rate to maintain the
broad Slight Risk of Excessive Rainfall with small adjustments to
account for 12z Hi-Res trends.

...Southwest...
12z Hi-Res trends supported by observational trends in moisture
plume placement slightly west, suggests a trimming of the eastern
portion of the larger Marginal Risk in New Mexico, including the
Rio Grande Valley of southern New Mexico.

...Southeast/Southern Appalachians...
Increasing return moisture within the anticyclonic portion of the
Northwest flow regime increases 925-85H flow upslope into the
southern Appalachians, eventually TPWs reach 1.25 to 1.5" by late
afternoon. Favorable orientation to the upper-level jet axis will
provide some increased larger scale ascent for outflow/evacuation
for thunderstorms that do develop. 06z-12z Hi-Res CAMs continue a
trend for increased convective development across NE GA into
upstate SC/W NC with HREF probs of 50% of 1"/hr and even a few
solutions resulting in 2"/hr and 5-15%. As such, have decided to
expand the Marginal Risk further north and eastward to account for
this trend. Otherwise, strong thunderstorms with enhanced
organization/bulk shear across S GA into N and Central FL look on
target for excessive rain with large HREF swaths of 2"/hr and
3"/3hrs over 65%. Given extreme rates necessary for exceeding
FFG, a Marginal Risk still appears appropriate risk level at this
time.

Gallina


---Prior Discussion---

...Northern Plains into the Upper Mississippi Valley/Upper
Midwest...
A shortwave trough will track eastward from the Northern Rockies
to the Northern Plains today, accompanied by a cold front tracking
from the northern High Plains this morning to the Upper
Mississippi Valley/Upper Midwest by early Saturday morning.
Tropospheric moisture will deepen in the pre-frontal environment
with precipitable water values reaching 1.5-2.0 inches by early
Friday evening (between the 90th percentile and max moving
average, per OAX/MPX/INL sounding climatology).

There should be an increasing risk of training cells by late
evening as west-southwesterly flow backs to south southwesterly in
response to the approach of a trough from the west...but the main
flash flood threat will come from individual cells with some
repeating cores containing 1-2"/hr rainfall rates. 00z HREF
exceedance probabilities for 2"+/3-hr are as high as 40-80% over
portions of the Slight Risk area (where above average rainfall
over the past 1-2 weeks corresponds to NASA SPoRT 0-100 cm soil
moisture near or above the 90th percentile).

Farther south across the middle/lower Missouri River Valley into
western Illinois, the same 00z HREF exceedance probabilities are
as high as 20-60%. The 2" exceedance over 3-hr is near the flash
flood guidance (FFG) threshold over this area, suggesting a more
marginal risk for flash flooding.

...Southwest and Four Corners area into the Southern/Central
Rockies...
Favorable monsoonal flow of moisture will continue from the
Southwest into the Southern/Central Rockies today as the closed
upper-level high remains centered over the Southern Plains. The
axis of above average PW values will not change appreciably,
supporting additional scattered to numerous late day and evening
showers and thunderstorms along with locally heavy rains from the
Southwest, eastern portions of the Great Basin and into the
Southern Rockies. Sub-hourly rainfall accumulations of 1"+ will
primarily drive the localized flash flood risk.

...Much of Georgia into North Florida and portions of Central
Florida...
A surface frontal boundary is expected to become quasi-stationary
near the Florida Panhandle today, providing additional convergence
(in addition to the typical sea breeze circulation) to help focus
convection. In addition, convection seems likely farther north
into Georgia along a quasi N-S axis of focused low-level moisture
transport/flux convergence on the backside of the offshore surface
high. The moisture-laden air mass (precipitable water values
1.6-2.0 inches, between the 80-90th percentile per JAX/TLH/FFC
sounding climatology) will support very heavy rainfall potential
and localized runoff issues, with the urban areas of Melbourne,
Jacksonville, Orlando, Tallahassee, and Atlanta particularly
vulnerable to heavy downpours. A Marginal Risk appears to be
adequate given the recent spell of below average rainfall during
the past few weeks.

Churchill/Bann


Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
337 PM EDT Fri Jun 24 2022

Day 2
Valid 12Z Sat Jun 25 2022 - 12Z Sun Jun 26 2022

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL/SOUTHERN ROCKIES AND THE ADJACENT HIGH PLAINS...

21z Update:
...Upper to Mid-Mississippi River Valley...
At the start of the forecast period (25.12z), strong thunderstorms
may be ongoing across northeastern MN to southeastern MN moving
into northwest WI along/ahead of the progressive cold front.
Increased forward speed and reducing available instability should
be reducing the strength of up/downdrafts; however, strong
moisture flux convergence will support any remaining cells with
efficient rainfall production with HREF probability of 1"/hr
ranging up to 35% crossing areas of naturally lower FFG and urban
locations such as Duluth, Minn-St.Paul, Rochester MN, Eau Claire
and La Crosse WI.

By mid-afternoon, the cold front will still be progressing
eastward across the MS Valley across S WI/E IA into N MO. Strong
insolation and very moist/high theta-E air will heat once again to
support 2000-3500 J/kg with moist profiles and TPWs of 1.75-2".
Solid height-falls/DPVA will continue the eastward progression of
the front providing strong moisture flux convergence for
convective initiation. Given available moisture and flux,
profiles will saturate quickly and support 2-2.5"/hr rain-rates.
However there are a few limitations, the front will continue to be
progressive to reduce overall duration and limit totals to locally
2-3" range. Additionally this is crossing an area of recently very
dry conditions (even Drought 0 conditions) and deep soil dryness
(0-40cm saturation ratios less than 10%), the strength of the
rates upon hard ground conditions could reduce infiltration and
increase overall runoff potential but still may not be a broad
enough area for all but highly localized flooding concerns. So,
in coordination with local forecast offices, given dry ground
conditions the overall coverage of exceeding FFG should be less
than 5% though likely non-zero which falls below Marginal Risk
criteria and therefore was not added at this time. Will continue
to watch the trends with the 00z cycle.

...Southwest U.S. into the Central/Southern Rockies...

Strong upslope flow will be highly confluent in the vicinity of
the stalled surface frontal zone across SE CO into KS on both
sides of the boundary. Ample early morning heating should support
sufficient convergence upslope to convect with ample moisture to
produce solid rainfall intensity throughout the afternoon into the
evening. The duration could become significant enough to present
a sizable flash flooding concern within the upslope region with
areal average QPF of 2-3" and occasional Hi-Res CAMs forecast over
those values...as such have expanded the Slight Risk further north
along the Colorado Rockies. Otherwise, the guidance has been
trending the frontal zone further south into Northern NM for the
better High-Plains thunderstorms along the front. Slow cell
motions, ample moisture and saturated ground conditions per AHPS
will maintain the Slight Risk if just a county or so further south
and east with the guidance trend.

Gallina


~~~Prior Discussion~~~
...Southwest U.S. into the Central/Southern Rockies and Adjacent
Plains...
Little change in the overall pattern with moisture still streaming
northward into the Central/Southern Rockies and making it into
parts of Colorado before being shunted eastward. Latest guidance
continues to show varying degrees of convective development over
the adjacent plains by late in the period as the deep moisture
encounters a cold front settling in from the north with the
GFS/FV3/RGEM having the strongest signal. As a result, have
maintained a focused Slight Risk over portions of the
Colorado/Kansas/New Mexico (and some adjacent portions of the
TX/OK panhandles) where the best guidance overlap exists. There
will be time to adjust the placement as additional hi-res CAM
guidance comes in later today, but deeper moisture and a focusing
mechanism should certainly be in place. Extended the Marginal Risk
area farther eastward into more of KS/OK and southwestern portions
of MO ahead of the front where the QPF signal is not as strong
(but has increased a bit) and antecedent conditions have been
drier.

...Far Southwest Georgia and Southeast Alabama into Peninsular
Florida...
A quasi-stationary surface boundary will continue to enhance the
typical sea-breeze circulation for more afternoon and evening
showers and thunderstorms from southern Alabama/Georgia into
Florida. Maintained a Marginal Risk in the area due to the
uncertainty of any overlap from expected heavy rainfall on Day 1,
but a targeted upgrade may be needed depending on how convection
evolves today. Regardless, the deep moisture already in place
should support heavy rain potential and isolated runoff issues,
especially in any urban areas.

Churchill/Bann


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
338 PM EDT Fri Jun 24 2022

Day 3
Valid 12Z Sun Jun 26 2022 - 12Z Mon Jun 27 2022

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL/SOUTHERN ROCKIES AND HIGH PLAINS...

21z update:

...Southwest...Southern Rockies and Adjacent High Plains...
Like in the Day 2 period, the frontal zone continues to trend a
bit faster, sagging further south. This reduces the potential for
increased upslope further north across the Central Rockies and
starts to shift the intersection/focus into northern New Mexico
and the southern Sangre de Cristo Range. Global guidance and
ensemble solutions all continue to focus across this area with
2-3" areal totals. Some tail-end Hi-Res CAM guidance suggests
even higher localized amounts are possible, but this is at very
low confidence. Additionally, guidance has a history of
retaining/developing increased instability for the next day cycle
of convection even though poorly handling debris clouds from the
prior day's convection that would limit overall instability
pattern, so while there is increasing convergence on placement
axis of excessive rainfall, there is still is moderate uncertainty
to the magnitude of the rainfall. So overall, have narrowed the
Slight Risk and dropped it southward to account for the synoptic
frontal timing, but if trends continue to be consistent in
placement and intensity it is not out of the realm of possibility
that a targeted Moderate Risk of Excessive Rainfall will not be
required. This is more likely given the recent deeply saturated
ground conditions in the region as well as larger burn scar areas,
so please stay tuned to updates with over the coming days.


....Appalachians into Adjacent portions of the Lower Great Lakes,
Ohio/Tennessee Valleys and Mid-Atlantic...
Little change in the guidance to help delineate a Slight Risk with
the 06-12z cycles of guidance. There remains some highlighted
areas of southern WV and portions of the KY/TN Cumberland Plateau
as well as a portion of Upstate NY near Syracuse, but a specific
location continues to bounce around too much to hoist a Slight at
this point, especially as the availability of Hi-Res CAMs will
start with the next 00z cycle. Only change was to slide the risk
area a bit further west with some slower trends noted,
particularly south across TN where there is some influence of
return easterly flow around the sub-tropical high and steering
flow becomes weaker/more confused.

Gallina


~~~Prior Discussion~~~
...Southwest U.S. into the Central/Southern Rockies and Adjacent
High Plains...
Anomalous tropospheric moisture looks to remain pooled across the
Four Corners region and adjacent portions of the High Plains on
Sunday, despite a frontal passage and drier air pushing southward
into the Central/Southern Plains and Mississippi/Ohio Valleys.
Scattered to numerous showers and thunderstorms are expected to
manifest once again in this environment with daytime heating,
leading to isolated to scattered instances of flash flooding
driven by sub-hourly rainfall rates of 1"+. The best chance for
localized totals approaching 2" will be across northern NM and
southern CO, where similar totals may have already occurred across
much of the same area on Saturday. While convection overall may
not be as intense and organized as on Saturday, antecedent
conditions still justify a Slight Risk given the potential for
more vulnerable antecedent conditions. While the Slight Risk area
reflects the best consensus of guidance for this cycle,
adjustments will likely be necessary through the weekend as prior
rounds of convection occur and more hi-res CAM guidance comes into
range for Sunday.

...Appalachians into Adjacent Portions of the Lower Great Lakes,
Ohio/Tennessee Valleys, and Mid-Atlantic...
A positively tilted trough and associated mature low pressure
system look to progress eastward into the Great Lakes region and
southeastern Canada on Sunday, sending a rather lengthy late
season cold front into the Appalachians from the Ohio/Mississippi
Valleys. The approaching front looks to coincide with peak daytime
heating for the Appalachians, presenting at least a Marginal Risk
for excessive rainfall for the mountain range and adjacent
portions of the Lower Great Lakes, Ohio/Tennessee Valley, and
Mid-Atlantic regions. Pooling of tropospheric moisture will send
precipitable water values soaring into the 1.7-2.0" range ahead of
the front, allowing for favorable heavy rainfall conditions with
marginally sufficient effective bulk shear (~20 kts) and 500-1500+
J/kg of SB CAPE. Relatively slow storm motions initially may allow
for localized 1-2" totals in a relatively short period, ending
fairly quickly into the early overnight hours as the frontal
passage occurs. A broad Marginal Risk area has been introduced as
a result, with the potential for a Slight Risk upgrade in a
portion of the area with future updates (highest odds being for
West Virginia and the vicinity, as this is where FFGs are lowest
and early signals suggest the highest potential for localized 2"+
totals).

...South Florida...
With the approach of a cold front across much of the
central/eastern CONUS and subsequent weakening/displacement of an
upper-level ridge that has been present across the Southeastern
U.S./Gulf region, thunderstorm coverage looks to become more
numerous across South Florida by Sunday. Sounding profiles suggest
little steering flow for typical daytime sea breeze initiated
convection, possibly assisted by the early stages of a TUTT
(tropical upper tropospheric trough) cell pinching off from a
parent upper-level trough over the western North Atlantic lifting
northeast. This TUTT cell may provide additional upper
lift/venting for deep convection, allowing for more
prolonged/intense thunderstorms over areas that have already seen
8-15 inches of rainfall earlier this month. The urban areas of
Miami and Fort Myers/Naples will see the greatest risk of any
localized flash flooding with the potential for 2-3"+ totals over
a short period.

Churchill


Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
309 PM EDT Tue May 10 2022

Valid 00Z Wed May 11 2022 - 00Z Sat May 14 2022

***Regularly scheduled Heavy Snow/Ice Discussions have ended for
the 2021-2022 season from WPC***

--This discussion may be updated over the summer months should the
forecast warrant--

~~Discussions will resume on or around October 1, 2022~~

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
306 PM EDT Fri Jun 24 2022

Valid 12Z Mon Jun 27 2022 - 12Z Fri Jul 01 2022

...Overview...

Guidance still agrees that a broad upper level ridge over the
southern half of the CONUS will be in place through much of the
medium range period, forcing storm tracks mainly through the
northern tier. A vigorous shortwave through the Upper
Midwest/Great Lakes will amplify some as it moves into the
Mid-Atlantic and the Northeast early next week, pushing a surface
cold front across the East and helping produce showers and
thunderstorms. Behind this, amplified ridging should build over
the Northwest U.S., and slide into the northern Plains as a closed
low/upper trough could settle over the Pacific Northwest, perhaps
by around Wednesday. Meanwhile, monsoonal moisture will continue
to persist into the Four Corners region through much of the
period, with the best potential for heavier to excessive rains to
remain across the south-central Rockies into early next week.


...Guidance Evaluation/Predictability Assessment...

Recent model guidance remains in good agreement through the medium
range time frame for the large scale pattern described above and
its evolution. This includes a couple of rounds of troughing over
the northeastern U.S. and ridging shifting from the northwestern
to north-central U.S. behind. Some slightly larger differences are
indicated in model guidance with the track of an eastern Pacific
upper low that should shift into southwestern Canada/northwestern
U.S. around Wednesday, and CMC runs have been most consistent in
leaving energy farther west. Then there are some placement
differences with the centroid of a central Canada/Hudson Bay upper
low, with the GFS on the western side Wednesday-Friday, which
could cause minor differences over the northern U.S. with
troughing and surface frontal placement. But the overall good
agreement allowed for the updated WPC forecast to use a
multi-model deterministic blend of the 00/06Z GFS runs and 00Z
ECMWF, CMC, and UKMET, phasing in the 00Z EC ensemble mean in
place of the UKMET by days 6-7, but with a majority deterministic
blend. This created a middle ground solution with decent
continuity from the previous issuance.


...Sensible Weather/Threat Highlights...

Anomalously high monsoonal moisture for this time of year, likely
tied at least in part to Tropical Storm Celia in the East Pacific,
will continue streaming into the Four Corners states into early
next week. Locally heavy to excessive rainfall will be possible
each day, particularly over sensitive burn scar areas and
considering the multiple day repeating nature of this activity.
The best chance for impactful rainfall looks to be over parts of
southern Colorado/New Mexico with favorable upslope flow
interacting with the moisture already in place. A Slight Risk was
maintained across northern New Mexico on the experimental day 4
excessive rainfall outlook for Monday where good model agreement
overlapped with areas that have seen anomalous rainfall already.
Activity then wanes around Tuesday-Wednesday, but there may be
another uptick in moisture by the latter part of next week.

A cold front should be fairly progressive through the East Monday,
but should focus enough moisture and instability to fuel
convection with possibly locally heavy rainfall. A settling of the
front across the Gulf Coast, as well as the next cold front
dropping into the region, should allow for enhanced rainfall into
the middle of next week from Florida to along the Gulf Coast as
aided by protracted onshore fetch of moisture. Elsewhere,
progressive fronts tracking across the Upper Midwest into the
Upper Great Lakes should produce a couple of rounds of rain and
storms through the workweek there, and rain may also focus over
the central Plains/Mid-Mississippi Valley by late week as a front
shifts into that area.

By early next week, temperatures all across the South should
finally trend back towards normal. Relatively cooler temperatures
with well below normal highs are likely to be most persistent over
parts of New Mexico and Colorado given the monsoonal clouds and
rain coverage. In the West, ridging through the region should
present an excessive heat threat across parts of especially the
Northwest into Monday with the above normal temperatures then
working through the northern half of the Rockies, Plains, Midwest
and then East Tuesday-next Friday as we head into July.


Tate/Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Heavy rain across portions of the Southern Rockies, the Central
Rockies, the Southern Plains, the Central Plains, and the
Southwest, Mon, Jun 27.
- Flooding occurring or imminent across portions of the Upper
Mississippi Valley, the Northern Plains, and the Northern Rockies.
- Excessive heat across portions of California, the Central Great
Basin, the Pacific Northwest, the Northern Great Basin, and the
Southern Plains, Mon, Jun 27.


WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, experimental excessive rainfall
outlook, winter weather outlook probabilities and heat indices are
at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml