Flooding Continues in Arenac County Along the Rifle River

                        

566

ACUS01 KWNS 161949

SWODY1

SPC AC 161948



Day 1 Convective Outlook

NWS Storm Prediction Center Norman OK

0248 PM CDT Mon Sep 16 2024



Valid 162000Z - 171200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTH

DAKOTA INTO NORTHWEST MINNESOTA AND PARTS OF COASTAL NORTH

CAROLINA...



...SUMMARY...

The threat for a few tornadoes will continue this afternoon and

evening over eastern North Carolina and vicinity. Thunderstorms

capable of producing severe gusts and large hail should occur today

in parts of the northern Plains. Isolated severe wind and hail also

appears possible across parts of the Great Basin to Four Corners.



...Four Corners/Arizona...

The primary adjustment was to expand the Marginal risk area

southward into eastern AZ. Dewpoints in the upper 50s to low 60s are

supporting MLCAPE values upwards of 1000 J/kg with negligible

inhibition based on latest RAP mesoanalysis estimates. A deepening

and expansive cumulus field across the region (including a few early

attempts at convective initiation) corroborate these estimates,

suggesting that adequate buoyancy resides across the region for

robust convection. Regional VWPs are sampling 30-40 knot winds

around 2-3 km AGL with stronger flow analyzed aloft in recent

upper-air analyses. Consequently, adequate deep-layer wind shear

appears to be in place to support organized convection, including a

supercell or two with an attendant severe hail/wind threat, though

storm coverage should remain somewhat limited due to modest forcing

for ascent (largely driven by orographic lift). For additional

information regarding near-term convective trends further north

across the Four Corners see MCD #2072.



...North Dakota...

The forecast largely remains on track across ND with only some

northwestward expansion of the Slight risk/15% hail probability

line. Latest high-res solutions continue to suggest that robust

convection will most likely develop near the vorticity maximum

(noted just to the west/southwest of Minot, ND as of 19 UTC) and

propagate northeast along the warm front. This scenario aligns well

with recent satellite trends with gradual convective development

observed ahead of the vort max and along the front amid continued

diurnal destabilization. This alignment of observed trends and

recent guidance yields sufficiently high confidence to warrant

adjusting the risk probabilities.



Elsewhere, the previous forecast remains on track. See the prior

discussion (below) or MCDs #2071 and #2073 for the latest details

regarding convective trends across coastal North Carolina and

portions of the Great Basin, respectively.



..Moore.. 09/16/2024



.PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Sep 16 2024/



...North Dakota into Northwest Minnesota...

Elevated thunderstorms which have produced sporadic, marginally

severe hail earlier this morning across parts of ND into northwest

MN have generally remained sub-severe over the past couple of hours

as a southerly low-level jet has gradually weakened. In the wake of

this activity, a surface low should consolidate over the northern

High Plains, with a front and convectively reinforced outflow

expected to lift slowly northward across ND this afternoon/evening

as an effective warm front. Airmass recovery is expected along/south

of this boundary, with steepening mid-level lapse rates, moistening

at low-levels, and daytime heating all contributing to moderate

instability by later this afternoon. While low/mid-level flow will

not be overly strong for most of the day, strengthening low-level

southerly flow is expected again this evening as a low-level jet

strengthens across the northern/central Plains.



Current expectations are for robust thunderstorms to develop

along/near the front late this afternoon and early evening. Enough

deep-layer shear should be present to support a threat of large hail

with any supercells initially. With time, some clustering should

occur. A potentially greater wind threat may exist through the

evening as activity spreads east-northeastward across

central/eastern ND into northwest MN. A tornado or two also appears

possible with any surface-based convection along/south of the front,

especially this evening as 0-1 km shear increases with the

strengthening low-level jet.



...Eastern North Carolina and Vicinity...

The surface low off the NC/SC Coast (Potential Tropical Cyclone 8)

is forecast by NHC to move northwest and inland across parts of SC

through this evening. A surface trough/weak baroclinic zone extends

northeastward from the low just off the NC Coast/Outer Banks. As the

system moves inland, enhanced low-level flow should turn more

east-southeasterly. Various NAM/RAP forecast soundings suggest that

as low 70s surface dewpoints advance inland along the coastal plain

of eastern NC, then only modest/filtered daytime heating will be

needed to support weak boundary-layer destabilization. Sufficiently

enlarged low-level hodographs should support a threat for a few

tornadoes with any low-topped supercells that can form offshore and

be sustained inland across coastal portions of eastern NC. The

Slight Risk for this region has been maintained with only small

adjustments based on recent observations and 12Z guidance.



...Great Basin into the Four Corners...

A deep, closed upper low centered over CA this morning will advance

slowly eastward across parts of the Great Basin through the period.

An attendant south-southwesterly mid-level jet will overspread

eastern portions of the Great Basin into the Four Corners region

this afternoon and evening. Although cloud cover remains prevalent

across parts of these areas, some daytime heating will encourage the

development of weak instability by mid to late afternoon. Stronger

mid-level flow and related deep-layer shear are forecast across the

Four Corners vicinity, where marginal supercell structures could

pose an isolated hail threat. Even though instability should

generally remain weak owing to limited low-level moisture,

occasional strong to severe wind gusts should be the main threat

with various small clusters that can form/consolidate and

subsequently spread north-northeastward through the early evening.

This wind threat will be locally maximized where filtered diurnal

heating can help steepen low-level lapse rates.



...Central High Plains...

Relatively high-based thunderstorms may develop this afternoon

across parts of the central High Plains, generally along/east of a

weak surface trough. This region will be mostly displaced to the

east of large-scale ascent associated with the upper low over the

West. Even so, a narrow zone of weak to moderate instability should

be in place across parts of central NE into western KS by peak

afternoon heating. Although flow through low/mid levels should

remain modest for much of the afternoon, a veering wind profile with

height should foster around 25-35 kt of deep-layer shear, sufficient

for some updraft organization. The primary uncertainty regarding any

isolated severe hail/wind threat remains whether convection will

initiate or not. Have therefore not added a Marginal Risk across

parts of the central High Plains with this update, but trends will

continue to be monitored.



$$






                

                        

907

ACUS02 KWNS 161732

SWODY2

SPC AC 161730



Day 2 Convective Outlook

NWS Storm Prediction Center Norman OK

1230 PM CDT Mon Sep 16 2024



Valid 171200Z - 181200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL

HIGH PLAINS INTO NORTHEAST MONTANA...



...SUMMARY...

Isolated to scattered severe gusts and hail are possible Tuesday

across a large swath of the High Plains region, mainly from late

afternoon into the evening. The greater concentrations of severe

storms may occur over the central High Plains into northeast

Montana.



...Synopsis...



A mid/upper cyclone is forecast over the Great Basin Tuesday

morning. This system will pivot northeast across the central Rockies

and into the northern High Plains through the forecast period. This

will bring a belt of strong south/southwesterly deep-layer flow

across CO/WY and adjacent portions of the High Plains. A surface low

will deepen over MT through the period, with a surface trough

extending southward through the central/southern High Plains. A warm

front is forecast to extend west to east from southeast MT into

north-central SD during the morning. With time, this boundary will

lift northward toward the International border during the nighttime

hours. As the system deepens and the low-level baroclinic zone over

the Plains strengthens, 850-700 mb flow is forecast to markedly

increase during the afternoon/evening to 30-50 kt. While deeper

boundary-layer moisture is forecast to remain east of the surface

trough axis and north of the warm front, steep midlevel lapse rates

will support pockets of weak to moderate instability. An arc of

thunderstorm activity, with a mix of line segments and discrete

cells, are expected to develop in the vicinity of the surface

low/warm front south/southeast along the surface trough during the

afternoon and evening hours.



...Eastern MT...



Strong ascent will overspread the region as the upper trough pivots

northeast during the late afternoon/evening. Boundary-layer moisture

will be greatest to the north of the warm front across

north-central/northeast MT, but capping will likely remain in place.

Storm motion will likely result in convection remaining elevated to

the cool side of the warm front. Nevertheless, steep midlevel lapse

rates and favorable vertical shear (elongated/straight hodographs)

will support some risk for large hail. As stronger forcing and

sufficient erosion of capping can overlap during the evening, strong

to severe wind gusts also will be possible.



...Northern/Central High Plains Vicinity...



Convection is expected to develop over the higher terrain of CO/WY

during the afternoon. Given strengthening mid/upper flow and weak

instability, some locally strong gusts could occur with this initial

activity near the core of the upper low over western/central CO. As

convection shifts east/northeast through the afternoon and into the

evening, strong heating is expected to result in a steep low-level

lapse rate environment across the High Plains. While deep

boundary-layer moisture will remain further east across the Plains,

steep midlevel lapse rates and surface dewpoints in the 50s F will

result in a corridor of around 1000-1500 J/kg MLCAPE from far

eastern CO into parts of western NE/SD. Strengthening midlevel flow

atop a deeply mixed boundary-layer will likely support severe gusts

(isolated gusts to 75 mph possible) with linear segments spreading

northeast across the central High Plains during the late

afternoon/evening.



...Southern High Plains Vicinity...



Further south, large-scale ascent will be weaker, with stronger

height falls focused north of the region. Nevertheless, low-level

convergence along the surface trough and modest instability (up to

1000 J/kg MLCAPE) will support initial thunderstorm development over

the higher terrain of south-central CO into north-central NM.

Forecast soundings show supercell wind profiles across the adjacent

High Plains by afternoon. Midlevel lapse rates will be somewhat

modest (around 6.5-7 C/km), but elongated/straight hodographs and

plenty of instability through the 700-300 mb layer suggest isolated

hail is possible. Steep low-level lapse rates also will support

isolated strong to severe gusts.



..Leitman.. 09/16/2024



$$






                

                        

564

FXUS63 KAPX 161857

AFDAPX



Area Forecast Discussion

National Weather Service Gaylord MI

257 PM EDT Mon Sep 16 2024



.KEY MESSAGES...



- Warm temperatures and rain-free weather persists, leading to

  elevated fire danger at times this week.



&&



.SHORT TERM /THROUGH TUESDAY/...

Issued at 243 PM EDT Mon Sep 16 2024



Abnormally high heights extending from New England westward into

the Great Lakes will continue to dominate the weather picture

through Tuesday (and well beyond). This will continue to result

in mostly clear skies, very warm daytime temperatures and

surprisingly comfortable nighttime temperatures. Guidance is a

few degrees cooler Tuesday for highs but still think it will

reach into the mid and upper 80s. Tonight will likely be a

little cooler than last night with lows ranging from the mid 40s

to the mid 50s. Light and variable winds through the period.



&&



.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...

Issued at 243 PM EDT Mon Sep 16 2024



Pattern Forecast: Above normal heights are expected to continue

through much, if not all, of the long term forecast period. Combined

with attendant surface high pressure dominating, above normal

temperatures with little to no chance for precipitation will be

the rule through the week ahead. Just beyond the end of the

forecast period, latest trends do support at least some low

precipitation chances, although certainly lots of time to sort

out details for nearly 10 days from now.



Forecast Details: Little in the way of sensible weather is

anticipated for midweek through the weekend. Daily high temperatures

through the work week largely in the low-mid 80s -- cooler near the

lakeshores. Trends favor highs cooling a touch this weekend

into early next week, but still mild 70s and low 80s for the

last half of September. Fire weather concerns appear to be

greatest early this week, but still some potential for

afternoon RHs to fall into the 30-40% range across interior

areas of northern lower.



&&



.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...

Issued at 201 PM EDT Mon Sep 16 2024



Stagnant weather pattern continuing over the next couple of

days (and beyond) with high pressure leading to mostly clear

skies and light winds. Although can not totally rule out patchy

ground fog tonight, continued drying from the lack of rainfall

and warm days will make any fog formation a tough chore.

Therefore, VFR cigs/vsbys are expected through the taf period.



&&



.APX WATCHES/WARNINGS/ADVISORIES...

MI...None.

MARINE...None.



&&



$$



SHORT TERM...AJS

LONG TERM...MJG

AVIATION...AJS






                

                        

354

ACUS11 KWNS 161919

SWOMCD

SPC MCD 161919

UTZ000-IDZ000-NVZ000-162115-



Mesoscale Discussion 2073

NWS Storm Prediction Center Norman OK

0219 PM CDT Mon Sep 16 2024



Areas affected...portions of northeastern Nevada...northwestern

Utah...and far southern Idaho



Concerning...Severe potential...Watch unlikely



Valid 161919Z - 162115Z



Probability of Watch Issuance...5 percent



SUMMARY...A few severe gusts are possible across portions of

northeastern Nevada, northwestern Utah, and far southern Idaho this

afternoon. A watch is not currently anticipated.



DISCUSSION...Thunderstorms have developed across portions of

northeastern Nevada to the east of an expansive upper-level closed

low centered over central California. Despite seasonably strong

mid-level flow across the region (40-50 kts of 500 mb flow),

deep-layer shear is not particularly impressive, with approximately

30 kts of effective bulk shear. Additionally, some lingering cloud

cover has resulted in slow surface destabilization across portions

of the region. In spite of this, however, there are some areas of 9

C/km or greater low-level lapse rates, per mesoanalysis and

short-term RAP forecast soundings. This may result in a threat for

severe wind gusts across the region this afternoon. Some uncertainty

exists with respect to the northward extend of the threat due to the

aforementioned cloud cover across portions of southern Idaho and

northwestern Utah. Regardless, some multicell clustering is expected

with time as storms move to the north-northeast.



..Supinie/Gleason.. 09/16/2024



...Please see www.spc.noaa.gov for graphic product...



ATTN...WFO...SLC...PIH...VEF...BOI...LKN...



LAT...LON   38551378 38301443 38321543 38811623 39661675 41011665

            41661624 42111581 42331501 42041387 41491341 40201319

            38951345 38551378