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MD 2059 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF EASTERN WA/OR...CENTRAL ID AND WESTERN MT
Mesoscale Discussion 2059 NWS Storm Prediction Center Norman OK 0331 PM CDT Tue Aug 29 2023 Areas affected...portions of eastern WA/OR...central ID and western MT Concerning...Severe potential...Watch possible Valid 292031Z - 292230Z Probability of Watch Issuance...40 percent SUMMARY...Scattered high-based convection should develop through the afternoon with a risk for damaging outflow winds and hail into the early evening hours. Scattered storm coverage and the potential for gusts to 70 mph suggests a WW is possible. DISCUSSION...Across portions of the Pacific Northwest, regional WV imagery showed a negatively tilted mid-level trough and jet streak ejecting eastward into portions of the northern Rockies. Ahead of the trough, broad synoptic ascent was evident in a deepening convective arc stretching from eastern WA/OR into portions of central ID. Despite limited surface moisture, (surface dewpoints in the 30s and 40s F), strong diurnal surface heating and cooling aloft are supporting 500-1000 J/kg of MLCAPE. As forcing for ascent continues through the afternoon, the sufficient buoyancy should allow for continued updraft development off of local terrain circulations. Scattered high-based storms should mature through the afternoon and continue into the early evening. As the trough and jet streak shift eastward, stronger mid-level flow will overspread the developing storms. Area RAP soundings show deep-layer shear of 30-40 kt which would favor some storm organization. A few longer-lived updrafts or clusters, including weak supercell structures, may evolve given the favorable shear and CAPE. With low-level inverted-v profiles present, strong negatively buoyant downdrafts capable of damaging gusts to 60-70 mph are possible. Small hail is also possible with the more sustained storms. As storms continue to develop, severe potential will likely increase over central and northeastern ID, into western MT this evening. Uncertainty on the severity of the threat is still relatively high given the modest buoyancy, but conditions will be monitored for a possible weather watch. ..Lyons/Thompson.. 08/29/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TFX...PIH...MSO...BOI...OTX...PDT... LAT...LON 44161184 43621273 43531359 44311599 45731761 47051768 48021582 47801386 46711288 45641214 44551173 44161184 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Tue Aug 29 2023 Valid 292000Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF FLORIDA IN ASSOCIATION WITH HURRICANE IDALIA...AND CENTERED OVER THE BITTERROOTS... ...SUMMARY... A few tornadoes will be possible late this afternoon through tonight, mainly from the west central Florida Peninsula into the Big Bend area, within the northeast quadrant of strengthening Hurricane Idalia. Occasional damaging wind gusts will be possible across the northern Rockies. ...20Z Update... Little change was made to the existing severe probabilities at 20Z, except for a minor eastward shift for a low wind threat into central MT where minimal instability will develop due to steepening lapse rates. For the Southeast, the threat for a few tornadoes will increase tonight, primarily after 03Z as stronger shear associated with Hurricane Idalia overspreads parts of the western FL Peninsula, and eventually into parts of the Big Bend. ..Jewell.. 08/29/2023 .PREV DISCUSSION... /ISSUED 1128 AM CDT Tue Aug 29 2023/ ...FL Gulf coast through tonight... Hurricane Idalia is strengthening as of midday over the southeast Gulf of Mexico and is forecast to make landfall Wednesday morning near the FL Big Bend as a major hurricane (please see latest NHC advisories for additional information). Storm motion will be largely parallel to the FL west coast into early tonight, so eastward expansion of the stronger wind field and more favorable low-level hodograph structures will be a gradual process (per the trends in the VWPs from Key West and Tampa). Surface observations show 77-80 F dewpoints across almost all of central/south FL, which will help maintain surface-based buoyancy into this evening and overnight. Thus, the primary increase in supercell/tornado threat is expected late this afternoon into tonight from near Tampa northward along the coast with the more cellular convection within the outer eastern/northeastern bands. ...Northern Rockies this afternoon/evening... A midlevel shortwave trough now over far northern CA and OR will progress east-northeastward toward the northern Rockies by this evening. Though low-level moisture is rather limited, strong surface heating/deep mixing will result in inverted-V profiles with weak buoyancy in advance of the midlevel trough and an associated cold front. Thunderstorm development is expected this afternoon through early tonight in the zone of ascent preceding the midlevel trough (and along the front). The highest confidence in storm development coincident with the steep low-level lapse rates and some enhancement to midlevel flow will be later this afternoon over the Bitterroots, where a few damaging outflow gusts of 60-70 mph will be possible. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Tue Aug 29 2023 Valid 292000Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF FLORIDA IN ASSOCIATION WITH HURRICANE IDALIA...AND CENTERED OVER THE BITTERROOTS... ...SUMMARY... A few tornadoes will be possible late this afternoon through tonight, mainly from the west central Florida Peninsula into the Big Bend area, within the northeast quadrant of strengthening Hurricane Idalia. Occasional damaging wind gusts will be possible across the northern Rockies. ...20Z Update... Little change was made to the existing severe probabilities at 20Z, except for a minor eastward shift for a low wind threat into central MT where minimal instability will develop due to steepening lapse rates. For the Southeast, the threat for a few tornadoes will increase tonight, primarily after 03Z as stronger shear associated with Hurricane Idalia overspreads parts of the western FL Peninsula, and eventually into parts of the Big Bend. ..Jewell.. 08/29/2023 .PREV DISCUSSION... /ISSUED 1128 AM CDT Tue Aug 29 2023/ ...FL Gulf coast through tonight... Hurricane Idalia is strengthening as of midday over the southeast Gulf of Mexico and is forecast to make landfall Wednesday morning near the FL Big Bend as a major hurricane (please see latest NHC advisories for additional information). Storm motion will be largely parallel to the FL west coast into early tonight, so eastward expansion of the stronger wind field and more favorable low-level hodograph structures will be a gradual process (per the trends in the VWPs from Key West and Tampa). Surface observations show 77-80 F dewpoints across almost all of central/south FL, which will help maintain surface-based buoyancy into this evening and overnight. Thus, the primary increase in supercell/tornado threat is expected late this afternoon into tonight from near Tampa northward along the coast with the more cellular convection within the outer eastern/northeastern bands. ...Northern Rockies this afternoon/evening... A midlevel shortwave trough now over far northern CA and OR will progress east-northeastward toward the northern Rockies by this evening. Though low-level moisture is rather limited, strong surface heating/deep mixing will result in inverted-V profiles with weak buoyancy in advance of the midlevel trough and an associated cold front. Thunderstorm development is expected this afternoon through early tonight in the zone of ascent preceding the midlevel trough (and along the front). The highest confidence in storm development coincident with the steep low-level lapse rates and some enhancement to midlevel flow will be later this afternoon over the Bitterroots, where a few damaging outflow gusts of 60-70 mph will be possible. Read more

Louisiana’s sugar cane farmers were using well water to irrigate their sugar cane as drought gripped nearly the entire state. Local crawfish farmers have also allowed cane growers to use their well water. KATC (Lafayette, La.), Aug 27, 2023

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 PM CDT Tue Aug 29 2023 Valid 301200Z - 311200Z Added an Elevated area for the Snake River Valley where winds of 20 to 25 mph and relative humidity of 15 to 20 percent are expected tomorrow. Fine fuels have started to dry in the region and will be increasingly susceptible to large fire, especially after dry and breezy conditions today. Also added an Elevated area across much of southern and eastern Wyoming. Winds of 20 to 30 mph with some gusts to 35 mph are expected across Wyoming tomorrow. Fuels in this area are not excessively dry, but given the high-end critical meteorological conditions, felt an Elevated delineation is warranted. Elsewhere no changes were needed. See previous discussion below. ..Bentley.. 08/29/2023 .PREV DISCUSSION... /ISSUED 0146 AM CDT Tue Aug 29 2023/ ...Synopsis... Two regions of Elevated fire weather conditions will be possible on Wednesday. Across portions of northern Montana, post frontal northerly flow will overlap drying fuels and relative humidity reductions to around 15-25 percent. Though fuels within this region are drying, they remain too moist to support inclusion of a Critical region at this time. Across the southern US, a tropical system impacting the Gulf of Mexico will bring an increase in northerly gradients across portions of Texas, Louisiana, Arkansas, and Mississippi. Areas across eastern Texas, northern Louisiana, and western Mississippi have seen prolonged heat and drought conditions, which has resulted in explosive fire behavior under more marginal meteorological conditions due to extremely critically dry fuels. Some questions remains how recent rainfall and any potential additional rainfall in the coming 24 hours will change the status of fuels. Given potential for sustained winds around 10-15 mph and relative humidity as low as 20 percent, an Elevated delineation was maintained with this outlook with a slight extension further south in Texas/Louisiana. This area will need to be monitored for Critical highlights in future outlook updates. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0200 PM CDT Tue Aug 29 2023 Valid 301200Z - 311200Z Added an Elevated area for the Snake River Valley where winds of 20 to 25 mph and relative humidity of 15 to 20 percent are expected tomorrow. Fine fuels have started to dry in the region and will be increasingly susceptible to large fire, especially after dry and breezy conditions today. Also added an Elevated area across much of southern and eastern Wyoming. Winds of 20 to 30 mph with some gusts to 35 mph are expected across Wyoming tomorrow. Fuels in this area are not excessively dry, but given the high-end critical meteorological conditions, felt an Elevated delineation is warranted. Elsewhere no changes were needed. See previous discussion below. ..Bentley.. 08/29/2023 .PREV DISCUSSION... /ISSUED 0146 AM CDT Tue Aug 29 2023/ ...Synopsis... Two regions of Elevated fire weather conditions will be possible on Wednesday. Across portions of northern Montana, post frontal northerly flow will overlap drying fuels and relative humidity reductions to around 15-25 percent. Though fuels within this region are drying, they remain too moist to support inclusion of a Critical region at this time. Across the southern US, a tropical system impacting the Gulf of Mexico will bring an increase in northerly gradients across portions of Texas, Louisiana, Arkansas, and Mississippi. Areas across eastern Texas, northern Louisiana, and western Mississippi have seen prolonged heat and drought conditions, which has resulted in explosive fire behavior under more marginal meteorological conditions due to extremely critically dry fuels. Some questions remains how recent rainfall and any potential additional rainfall in the coming 24 hours will change the status of fuels. Given potential for sustained winds around 10-15 mph and relative humidity as low as 20 percent, an Elevated delineation was maintained with this outlook with a slight extension further south in Texas/Louisiana. This area will need to be monitored for Critical highlights in future outlook updates. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

000
ABPZ20 KNHC 291723
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Tue Aug 29 2023

For the eastern North Pacific...east of 140 degrees west longitude:

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm Irwin, located more than 1200 miles west of the southern tip
of the Baja California peninsula.

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster Reinhart

The city of Sequim declared a drought emergency, and residents were urged to voluntarily conserve water. The Washington Department of Ecology declared a drought emergency in late July for watersheds including the Dungeness River basin, which supplies Sequim with water via wells. Low stream flows jeopardize operations at fish hatcheries and salmon migration, so fishery and irrigation managers were coordinating to optimize stream flows to aid pink salmon presently migrating up the Dungeness River to spawn. My Clallam County (Port Angeles, Wash.), Aug 25, 2023

Drought in Canada led to a decline in the goose population, which will result in fewer geese, or “honkers,” for Torrington’s 2Shot Goose Hunt in early December. Canada’s potholes and small ponds where ducks and geese breed went dry this spring, leading to lower numbers of ducks and geese. In some places, the Canada goose population was up to 42% lower. In the Rocky Mountain region, counts were down about 25%. Cowboy State Daily (Lander, Wyo.), Aug 28, 2023

Wildfires continued to burn in the southwest part of Louisiana. The blaze in Vernon Parish blackened nearly 4,000 acres of forest and was 40% contained. KALB-TV (Alexandria, La.), Aug 28, 2023

The Tiger Island Fire in Beauregard Parish charred at least 33,000 acres and was 50% contained. A special firefighting team arrived to help battle the flames. KALB-TV (Alexandria, La.), Aug 28, 2023

Business has been down 20% for an inner tube and kayak rental service with a couple of locations in eastern Iowa. Rivers were low due to little precipitation, and low river levels meant that renters sometimes damaged equipment by popping tubes and scraping the kayaks. The low water levels may have resulted in a financial loss of $4,000-$5,000. Sand Lake in Iowa City was too low to even have a season renting equipment. KCRG Online (Cedar Rapids, Iowa), Aug 29, 2023

More than 450 fires have blackened parts of Louisiana as record-breaking heat and severe drought conditions gripped the state. The Tiger Island Fire, the largest wildfire in the state’s history, grew from about 15,000 acres on Friday, Aug. 25 to more than 33,000 acres Sunday and was just 50% contained. Two lives have been lost in fires in St. Tammany and Washington parishes. Louisiana, one of the wettest states in the country, averages 771 wildfires a year, according to 10-year average data from the Louisiana Agriculture and Forestry Department. The state has averaged 21 wildfires per day over the past several weeks. The Washington Post (D.C.), Aug 29, 2023 Hundreds of wildfires were burning in Louisiana amid intense heat and drought. The Tiger Island Fire in Beauregard Parish in western Louisiana led to evacuation orders and blackened more than 10,000 acres, or approximately 16 square miles. The flames reached 300 feet in height. A statewide burn ban that took effect in early August remained in place. Firefighters were exhausted from battling blazes and pleaded with the public to observe the burn ban. The Associated Press (Baton Rouge, La.), Aug 23, 2023

Mineral Wells was in Stage Two water restrictions and was days away from entering Stage Three restrictions when water usage should be cut by 30%. Lake Palo Pinto was at 35% capacity on Aug. 29. Water from the Brazos River was being pumped into the lake to increase supply, but treating the water was costly and time-consuming. Special equipment required to treat the water was delayed. WFAA (Dallas, Texas), Aug 29, 2023 Drought conditions in the Mineral Wells area have the region on track to hit stage 3 drought restrictions this summer. The Mineral Wells city manager also secured another significant source of raw water for the district, which serves customers in Palo Pinto and Parker counties. The district will purchase Brazos River water, which would be blended with water from Lake Palo Pinto. Weatherford Democrat (Texas), May 23, 2023 Lake Palo Pinto dropped below the trigger level for Stage II of Mineral Wells’ drought contingency plan. Starting April 1, all outdoor water use is prohibited except for animals. The aim is to curb total water use by 25%. Weatherford Democrat (Texas), March 24, 2023

Drought has caused the ground in St. Martinville to shift and crack and break waterlines. City maintenance crews shut off the water citywide to repair the leaks. The city was under a boil order until further notice. KATC (Lafayette, La.), Aug 28, 2023

No watches are valid as of Mon Aug 28 21:42:02 UTC 2023.

No Mesoscale Discussions are in effect as of Mon Aug 28 21:42:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0351 PM CDT Mon Aug 28 2023 Valid 301200Z - 051200Z Tropical storm (soon to be hurricane) Idalia will move into the Southeast on Wednesday bringing strong winds and heavy rain to much of Georgia and Florida, into the Carolinas. On the western periphery of this tropical system, dry northerly winds may result in some elevated to critical fire conditions in drought stricken regions from central Texas to western Mississippi. An amplifying mid-level trough will cross Montana on Wednesday with a surface low and cold front also traversing the state. In the wake of this cold front, dry and breezy westerly flow is expected across northern and eastern Montana. Some dry and breezy conditions are expected in a similar region on Thursday, but rainfall Wednesday night and Thursday may result in some wetting rain and limit fire weather concerns, at least for some portions of north-central and eastern Montana. Several days of dry and breezy conditions are expected from Nevada to Wyoming beneath moderate mid-level flow and a deeply mixed airmass. However, fuels across this region do not support significant fire spread due to recent precipitation. ..Bentley.. 08/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

5-Day Uncertainty Track last updated Mon, 28 Aug 2023 20:32:14 GMT


Wind Speed Probabilities last updated Mon, 28 Aug 2023 21:35:41 GMT

Issued at 1100 AM HST Mon Aug 28 2023 000 WTPZ45 KNHC 282031 TCDEP5 Tropical Storm Irwin Discussion Number 8 NWS National Hurricane Center Miami FL EP102023 1100 AM HST Mon Aug 28 2023 Deep convection has been fading away, and Irwin is getting closer to becoming a post-tropical cyclone. Satellite imagery suggests mid-level dry air is wrapping around much of circulation and an area of decaying convection remains over the northern portion of storm. The initial intensity remains at 35 kt based on recent ASCAT passes. Irwin has yet to make its much anticipated westward turn and is still moving west-northwestward at 9 kt. Still, model guidance insists the cyclone will go to the west shortly and remains tightly clustered. The general westward motion, with a increase in forward speed, is expected to continue through the forecast period. The latest track forecast has shifted to the north and lies between the previous forecast and the simple consensus aids. The storm appears to be in the process of weakening. The extent of tropical-storm-force winds in the northeast quadrant has decreased significantly based on the satellite-derived surface wind data. Sea surface temperatures and mid-level relative humidities are expected to decrease along the forecast track and Irwin is expect weaken further in the next day or so. The storm is still forecast to become a remnant low within 48 hours, though this could happen sooner. FORECAST POSITIONS AND MAX WINDS INIT 28/2100Z 18.6N 124.2W 35 KT 40 MPH 12H 29/0600Z 19.0N 126.3W 30 KT 35 MPH 24H 29/1800Z 19.0N 129.0W 30 KT 35 MPH 36H 30/0600Z 18.9N 131.7W 30 KT 35 MPH 48H 30/1800Z 19.0N 134.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 60H 31/0600Z 19.0N 136.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 31/1800Z 19.2N 137.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 01/1800Z 19.3N 140.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 02/1800Z 19.2N 142.4W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Bucci