Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/08/18

Area Forecast Discussion
National Weather Service Denver/Boulder CO
904 PM MDT Tue Aug 7 2018 .UPDATE... Issued at 904 PM MDT Tue Aug 7 2018 Convective activity has pushed east over the plains this evening, with just a few storms left. Have decreased PoPs over the mountains and urban corridor for this, and will let the current Severe Thunderstorm Watch expire. However, the upper trough axis is still stretched northeast to southwest through South Dakota and Wyoming, with some isolated stronger storms ahead of it in Wyoming and Nebraska. Have left slight chance to chance PoPs over the eastern plains to account for this, while further west towards the urban corridor and mountains the airmass is drying. Some southeasterly winds south of the Palmer Divide seems to be brining some return moisture that will bring showers and thunder to Park County and the Palmer Divide over the next few hours. Will keep a mention of possible storms over the aforementioned areas through midnight, then still a slight chance east of the Palmer after midnight. && .SHORT TERM...(This evening through Wednesday) Issued at 300 PM MDT Tue Aug 7 2018 Hot upper level ridge towering over the western one-forth of the CONUS will move little next 24 hours. Forty-80kt northwest flow aloft on its east face appears to contain another weak mid-level shortwave disturbance. This wave is now over central Wyoming as per GOES-16 water vapor satellite imagery and model 500-250 mb QG vertical velocity fields. This disturbance is forecast to sweep southeast over northeast Colorado this evening. Next is the northward flow of low-level moisture on the plains of ern CO. The cumulus clouds racing northward over Lincoln and Washington Counties marks the axis of this moisture feed. Sfc convection has been much slow to initiate today, but RAP and NAMNest show the CIN all but gone now. Model CAPE fields at the present time anywhere from 1200-2400 J/Kg on the plains. Over the next few hours, CAPES increase even further with a bulls eye of sfc based CAPE close to 4000 J/Kg sitting southeast of the Denver metro area around 23z today, near the center of a Denver Cyclone. Cyclone is already evident in observation and HiRes model wind fields. Douglas, Elbert and Lincoln Counties already under a Severe T-storm Watch. I can see this watch being extended northward to include at least the southern half of the I-25 corridor, including the greater Denver metro area. Biggest concern with the available deep layer shear and very high CAPE will be very large hail and damaging outflow winds. It`s conceivable storms firing over and south of the Denver metro area during the next couple of hours could produce hailstones at least 2 inches in diameter. Looking north again, isolated supercells now forming in southeast WY are expected to track southeast acrs northeast CO counties during the next several hours. These storms will also have the potential to produce very large hail, possibly up to 1.75 inches in diameter. Could see this area also coming under a SVR t-storm watch. Storms just about anywhere will be capable of producing strong outflow winds. Could see t-storms on the plains lingering late into the evening, and possibly beyond midnight in the far eastern CWA counties. Deeper moisture out there could lead to heavier rainfall amounts, possibly resulting in localized flooding. Most of this storm activity should end by midnight with drier air spreading down from WY in the wake of this evening`s shortwave trough. On Wednesday...northwest flow aloft appears a bit drier over the area. However, models show yet another weak mid-level disturbance embedded in this flow sweeping over northeast CO by mid to late afternoon. QPF and model radar reflectivities not as widespread or as intense as today. Therefore, will go with lower PoPs. Even with less cloud cover and slightly warmer temps aloft, high temps expected to be about the same as today. .LONG TERM...(Wednesday night through Tuesday) Issued at 300 PM MDT Tue Aug 7 2018 Trend toward more quiet weather in the extended as atmosphere dries out and high pressure builds. 500mb high pressure centered over Nevada through the end of the week extending north to Canada. Upper flow over Colorado is northerly and weak for the rest of the work weak. By Friday a trough moving into British Columbia causes a positive tilt to the ridge and flattens the ridge out, and upper flow even becomes northeast across the forecast area through the weekend. Monday and Tuesday upper flow becomes more variable. Moving on into the weekend jet stream westerlies remain north along Canadian border, with weak flow aloft over the forecast area. GFS and ECMWF Monday and Tuesday bring a closed off upper low north from Texas into western Kansas, but right now keep it east of the forecast area. Absent any forcing will have diurnal chances for showers and thunderstorms over the higher terrain, and dry out on the plains on a daily basis through the extended period. Light southerly low level flow over the plains in weak lee trough, with light terrain affected winds in the mountains. No change in airmass during this period, and temperatures will be consistently near normal with little change from day to day for highs and lows. Highs in the 70s mountains and 80s plains, and lows in the 40s mountains and 50s plains. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday afternoon) Issued at 904 PM MDT Tue Aug 7 2018 Best storm chances have moved east, yet some weak echoes continue to form north of DEN - these aren`t expected to impact the airports though. East- southeast winds of 7-14 kts will turn southerly later this evening at 5-12 kts. Another upper- level weather disturbance will swing out of Wyoming tomorrow afternoon to produce isolated to widely scattered thunderstorms over and near the Front Range, but storm coverage is expected to be less with a drier and slightly less stable atmosphere. One or two storms could move across the metro area after 21z producing a brief rain showers and wind gusts to 35 kts. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Kriederman SHORT TERM...Baker LONG TERM...Hanson AVIATION...Baker/Kriederman
Area Forecast Discussion
National Weather Service State College PA
1137 PM EDT Tue Aug 7 2018 .SYNOPSIS... Humid and stormy weather will continue through midweek with strong to locally severe thunderstorms possible. Thursday looks like a drier day before an unsettled pattern redevelops over the weekend through early next week. && .NEAR TERM /THROUGH WEDNESDAY/... Radar is starting to quiet down as the strongest cluster of storms moves through the lower Susq Valley. HRRR indicates just a couple of isolated cells after 00Z/8PM. So I trimmed the POPs down showing a mainly quiet overnight. && .SHORT TERM /WEDNESDAY NIGHT THROUGH 6 PM WEDNESDAY/... After a quiet night, convection will redevelop again on Wednesday as the weakened frontal boundary remains over the northeast US and an upper level trough begins to swing over the Great Lakes. There will be another Marginal Risk for severe storms with moderate CAPE and slightly better deep layer shear than we saw today. We could also see the threat for flooding rain with a very juicy airmass in place. Models show PWATs at or around 2" over the entire region back into the OH Valley. The wet summer of 2018 shows no signs of abating soon. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Drier wx is likely on Thursday before an unsettled pattern unfolds over the weekend through early next week. Models and ensembles show a cut off low developing over the OH Valley by the end of the weekend. Widespread precipitation is likely to the east of the low along the Appalachians into early next week with some potential for a heavy rainfall threat considering slow system movement. The distribution and intensity of the rainfall will be sensitive to the evolution of the upper low/trough. This will be something to monitor in the coming days especially given how wet it has been this summer. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... A shower or tstorm is possible late tonight, mainly over northwest Pa, in association with a weak warm front lifting through. However, the main concern overnight will be fog. Across eastern Pa, mostly clear skies and light wind will allow valley fog to form, especially in those locations where rain fell this evening, such as KIPT and KLNS. Over the western half of the state, increasing mid level cloudiness could inhibit radiational cooling and fog potential. Any fog should dissipate between 13Z-15Z. The focus will then shift toward afternoon and evening showers and thunderstorms associated with an approaching cold front. Brief reductions appear likely as this system moves through during the PM hours. .Outlook... Thu...AM low cigs possible KBFD/KJST. Fri...AM valley fog possible western Pa. Isold PM tsra impacts possible. Sat...Scattered PM tsra impacts possible, mainly southern Pa. Sun...AM low cigs possible central mountains. Scattered PM tsra impacts possible. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...Ceru/Tyburski LONG TERM...Steinbugl AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Dodge City KS
1040 PM CDT Tue Aug 7 2018 ...UPDATE TO SYNOPSIS... .SYNOPSIS... Issued at 1038 PM CDT Tue Aug 7 2018 WV imagery indicates a westerly flow aloft prevailing across the Western High Plains. Near the surface, a stalled frontal boundary extends from extreme southeast Colorado southeastward into the Texas Panhandle. && .SHORT TERM...(This evening through Wednesday) Issued at 155 PM CDT Tue Aug 7 2018 There will be a chance for an isolated thunderstorm or two late today but the better opportunity for thunderstorms for southwest Kansas will occur overnight. 700mb moisture will be present late today ahead of an upper level trough as it crosses southwest Kansas late today. Based on 00z Wednesday instability and 850mb to 700mb forcing forecast late day there will be a chance for an isolated thunderstorms or two ahead of this upper wave in south central Kansas. Several short term models also hinted at this earlier today so will therefore continue with some very small chances for late day convection southeast of Dodge City. Severe weather late today with these isolated storms are not expected at this time time given the late day instability and 0-6km shear but should any storm develop late today it may be capable of producing some small hail or even some gusty winds. Another round of convection will be possible across southwest Kansas overnight. This round of convection appears be to more likely given the location of the 0-1KM theta-e axis, 850mb warm air advection developing and location of the mid level baroclinic zone ahead of another upper level system. This area of convection will initially begin in Colorado and then move across southwest Kansas during the overnight hours. The primary hazard from these storms overnight will be strong gusty winds along with period of heavy rainfall. These overnight thunderstorms will taper off from northwest to southeast early Wednesday morning as the upper level trough crosses southwest Kansas. An upper level ridge will slowly move east across the western United States mid week as another upper level disturbances rotates around this ridge axis, down the north to northwest flow, and across the Central Plains late Wednesday. As this next upper wave passes Wednesday afternoon it will bring with it some increasing afternoon clouds along with another chance for thunderstorms to portions of western Kansas. Temperatures will be cooler Wednesday afternoon compared to the past few days given the increasing clouds and chance for precipitation. Highs will be mainly in the 85 to near 90 degree range. .LONG TERM...(Wednesday night through Tuesday) Issued at 155 PM CDT Tue Aug 7 2018 Thursday and Friday...the western United States upper level ridge will slowly move into the Rockies as the next in a series upper level waves rotates around this upper ridge axis and down the northwest flow into the Central Plains. As this next upper wave moves across the central and southern Rockies the GFS and ECMWF were both are in agreement with cutting off this upper level system from the mean flow early this weekend. As this closed circulation develops there will be another chance for thunderstorms on Friday and possibly even again early this weekend, especially in south central Kansas. Temperatures late week and over the weekend still appears to be on the cool side compared to the temperatures that were experienced earlier in the week. Based on the 850mb temperature trends the highs for the last half of the work week and over the weekend are expected to range from the upper 80s to around 90. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 500 PM CDT Tue Aug 7 2018 Scattered thunderstorms are expected during this TAF forecast cycle, mainly during the overnight hours tonight. Retained the integrity of the inherited 18z TAFs, as the TEMPO groups still aligned with the latest HRRR iterations. HRRR shows convection developing near the terminals around the 05-06z Wed timeframe, and subsequently spreading SE through 12z Wed. Convective impacts are most likely at GCK/DDC/LBL. Model consensus continues to keep HYS dry, with perhaps a period of VCSH around 12z Wed, and kept the HYS TAF dry. Winds outside of thunderstorms will continue to be light, generally less than 10 kts, and at times variable in direction. && .PRELIMINARY POINT TEMPS/POPS... DDC 65 86 64 89 / 60 20 10 0 GCK 64 85 63 88 / 50 10 10 0 EHA 63 85 62 88 / 60 10 20 10 LBL 66 86 63 89 / 60 20 20 10 HYS 64 88 65 90 / 10 20 10 10 P28 69 88 66 91 / 60 30 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JJohnson SHORT TERM...Burgert LONG TERM...Burgert AVIATION...Turner
Area Forecast Discussion
National Weather Service Des Moines IA
645 PM CDT Tue Aug 7 2018 .SHORT TERM.../Tonight through Wednesday/ Issued at 316 PM CDT Tue Aug 7 2018 Storms have developed this afternoon along a boundary associated with a shortwave trough moving across the state. Overall, HRRR has had the best handle on the convection earlier this morning and through the early part of the afternoon. The storms across north central Iowa are expected to continue to move to the southeast, with additional development along a boundary across central Iowa this afternoon, continuing and strengthening some through south- southeast Iowa 00-03Z. While stronger storms are possible, the severe threat with these storms is relatively low. Instability and shear parameters are marginal, with MLCAPE around 1000-15000 J/kg and shear 35-40kts. There is also an indication that a few funnels may be possible with higher surface vorticity across central portions of Iowa. With the trough pushing east, overnight lows will be a few degrees cooler than last night. With ample moisture, fog is expected to develop around and east of I-35 by 08Z, lasting through 14z. .LONG TERM.../Wednesday night through Tuesday/ Issued at 316 PM CDT Tue Aug 7 2018 The upper level ridge over the western CONUS will continue to become more amplified then begin to move east Wednesday night and through the end of the week. As this occurs, the 850 mb thermal ridge will move east into Iowa. Warmer temperatures will arrive as a result for Thursday with highs in the mid to upper 80s north to low to mid 90s south. Good mixing should occur over southern Iowa by Thursday afternoon allowing for dew points to drop into the low to mid 60s, which will lessen the heat impacts. Farther north, pooling dew points in the low 70s will lead to more humid conditions along with greater instability. A boundary will drop into Iowa by the afternoon and evening and may spark thunderstorm development. An upper level low will begin to form over the central Great Lakes late Friday and will form a blocking pattern thru Monday before the system finally begins to move east. Friday through the weekend will be mainly dry with high temperatures in the 80s. The next chance of precipitation will arrive towards the end of the period as the upper level low departs to the east and releases the block. && .AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/ Issued at 644 PM CDT Tue Aug 7 2018 Isolated convection may briefly affect TAF sites early this evening, but confidence towards dry, VFR conditions increases sharply by shortly after sunset. The next question becomes fog potential early Wed with lingering low level moisture and light winds. Have included MVFR to isolated IFR conditions at most sites for now until confidence in other trends increases. Conditions should improve to VFR by mid morning. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Hagenhoff LONG TERM...Donavon AVIATION...Small
Area Forecast Discussion
National Weather Service Goodland KS
943 PM MDT Tue Aug 7 2018 .SHORT TERM...(This evening through Wednesday) Issued at 319 PM MDT Tue Aug 7 2018 Pops have been increased for the overnight period, as a shortwave is expected to pass over our eastern CWA from Yuma County, Colorado to potentially Wichita County, Kansas. Disturbance may be enough lift to aid in thunderstorm development. Convection is expected to develop over eastern Colorado and die off over the plains. Biggest area of favored conditions will be the Palmer Dive and to the east of it. West Northwest wind flow aloft will aid in bringing in dryer area, especially in the mid and upper levels. Model soundings are showing favorable subsidence tomorrow. Pwat values are still sitting ~1" in the low levels. There is currently no well-defined synoptic support for convection. But short term models like the HRRR and HREF are pointing to late night convection from 06 to 12Z . MLCAPE values are ~1000-1500 with about 35-40 knots 0-6 km shear. Expecting isolated storms with marginally severe hail and winds. Tonight, lows will sit in the upper 50s to lower 60s across the Tri-State area. However, depending on convection, this may drop 5 to 10 degrees lower. Lastly, tomorrow`s highs will be in the mid to upper 80s, with another round of slight chances for convection in the late afternoon. An isolated severe thunderstorm or two cannot be ruled out. .LONG TERM...(Wednesday night through Tuesday) Issued at 222 PM MDT Tue Aug 7 2018 A shortwave embedded in upper level ridge flow expected over the northern Plains by Thursday morning. This shortwave moves southeast over eastern Kansas by Friday night. During the southeastward progression of this shortwave, thunderstorm chances will exist for parts of the Tri-State region during the afternoon and overnight hours. The shortwave will extend into the southern Plains due to upper level lows settled over Oklahoma and Texas. This trough becomes split Sunday with the main trough over the Midwest and a cutoff low remaining over the southern Plains. By Tuesday morning, the cutoff low over Texas migrates northward towards strong flow aloft creating a shortwave trough over Kansas. The migration of the cutoff low over Kansas could potentially bring precipitation to the Tri-State region Tuesday. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 943 PM MDT Tue Aug 7 2018 An isolated thunderstorm cannot be entirely ruled out at the GLD terminal early this morning (06-12Z), however, confidence is too low to warrant explicit mention with the 06Z TAFs. Otherwise, VFR conditions and light/variable winds are expected to prevail through the TAF period. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...EV LONG TERM...NEWMAN AVIATION...VINCENT
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
646 PM CDT Tue Aug 7 2018 .SYNOPSIS... Issued at 316 PM CDT Tue Aug 7 2018 H5 analysis from this morning had a strong area of low pressure roughly 1000 miles off the coast of Oregon. Ridging extended downstream of this feature from Oregon, north into central British Columbia. Downstream of this feature, low amplitude flow extended across the remainder of the northern half of the CONUS. Within this flow, numerous shortwaves were noted from the central plains, east into the Mid Atlantic. Further west, strong shortwaves were noted over swrn Minnesota, and a second, weaker wave over western Montana. At the surface, low pressure was located over eastern Iowa with a cold front extending to the southwest into southwestern Kansas. Weak high pressure had settled in behind the front and was located over nern Nebraska. After fog and low cloudiness across swrn Nebraska into portions of central and north central Nebraska this morning, skies were clear this afternoon. Readings as of 3 PM CDT ranged from 81 at O`Neill to 85 at Valentine. && .UPDATE... Issued at 645 PM CDT Tue Aug 7 2018 A 21z blend of the HRRR, RAP and HREF models has correctly predicted the development and trajectory of the ongoing thunderstorms over the cntl Sandhills. The 00z KLBF sounding indicates 25kt winds at 500mb which is producing very modest wind shear. The storms should track into nern Lincoln and Custer counties this evening and dissipate. && .SHORT TERM...(This evening through Wednesday) Issued at 316 PM CDT Tue Aug 7 2018 he main forecast challenges tonight are thunderstorm chances and fog potential, mainly over southwestern portions of the forecast area. During the late afternoon hours Tuesday, the shortwave which was analyzed over western Montana, will dive to the southeast into Wyoming, leading to the development of thunderstorms over the higher terrain of sern Wyoming and the front range of Colorado. The latest HRRR, Nam12 and WARW develop convection INVOF the Cheyenne ridge during the 21-00z time frame this afternoon forcing this into the southern panhandle, then far southwestern Nebraska this evening as it rides northwesterly mid level winds. Will continue the isolated pops in the forecast this evening in the sern panhandle and far southwestern Nebraska. As for the severe threat, not totally sold on a total absence of severe storms across the southwest tonight. Deep layer shear tonight is on the order of 30 to 35 KTS in the far southwest and h7-h5 lapse rates are favorable for hail. That being said, wouldn`t be surprised to see a strong to low end severe storm this evening in the far southwest. Will hit this in the afternoon issuance of the HWO. With respect to fog potential tonight, persistence based on what occurred the last couple of nights, would dictate a mention of fog. However, looking at the high res models and numerical guidance for tonight, there is no support for fog attm. .LONG TERM...(Wednesday night through Tuesday) Issued at 316 PM CDT Tue Aug 7 2018 The upper level low off the coast of Oregon, will approach the west coast of the CONUS midweek amplifying the ridge across the intermountain west. As the ridge amplifies in the west, one last shortwave will drift south across Nebraska Wednesday afternoon with an increased threat for thunderstorms mainly south of Interstate 80. After Wednesday night, the ridge will amplify further across the intermountain west, taking a positive tilt toward the northern plains toward the end of the week. This will place the forecast area in northerly or north northeasterly flow in the mid levels. With this flow regime, dry conditions are expected at least through Saturday. The next outside chance for pcpn may arrive across the area Sunday into Monday. The mid range solutions this morning have trended the best forcing further north into North Dakota and southern Canada, so a dry forecast will be retained with this package. Temperatures in the long range will be slightly above average with highs generally in the upper 80s to lower 90s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 645 PM CDT Tue Aug 7 2018 Mostly isolated thunderstorms should dissipated 03z-09z tonight. No thunderstorm activity is expected Wednesday. Patchy valley fog may develop overnight, mainly in the Platte valleys. burnoff should occur 14z Wednesday morning. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...CDC SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
832 PM CDT Tue Aug 7 2018 .UPDATE... 826 PM CDT Stabilizing influence from earlier storms/clouds and lake breeze is evident as additional showers attempt shift into NE Illinois this evening and then fade given the more subtle forcing aloft. Next shortwave over Iowa will pivot through the area this evening and more so overnight. Coverage will remain low, but subtle surface boundary ahead of this will maintain shower chances mainly along and south of I-80, maybe brief t-storm as the MLCAPE axis remain place due to continued humid conditions. Areas north of this axis have very limited thunder concerns for evening outdoor activities. The light pressure gradient and moist low levels still suggest some fog potential overnight, especially later tonight towards daybreak, just not clear yet as to the extent given the clouds ahead of the upper wave. KMD && .SHORT TERM... 228 PM CDT Today through Tonight... Evolution and timing of shower/thunderstorms late this afternoon and evening are primary near-term forecast concerns. Regional radar mosaic depicts an area of rain/isolated thunderstorms spreading northeast across the forecast area this afternoon. This activity is in association with a mid-level short wave, which will continue its transit of the area through late afternoon. Extensive cloud cover has helped to limit destabilization, with temps becoming further cooled by rainfall across areas north of I-80, thus there has been relatively little lightning with this activity. Still, RAP soundings and SPC mesoanalysis date depicts 500-1000 J/kg of MLCAPE exists, particularly along an axis of slightly higher dew points roughly along I-80 into northwest Indiana. This location may have a greater potential for isolated/scattered thunderstorm development this afternoon into early evening as the mid-level wave approaches. 35-40 kt mid-level speed max will also produce an increase in deep layer shear, suggesting at least an isolated strong/severe wind potential with any more organized cells or clusters. Much of the convective rainfall moving across north central Illinois is fairly low-topped, with shallow reflectivity centroid heights, which suggests these may be more efficient rainfall producers than their returns would indicate. This is also supported by low visibility observations as these cores pass various AWOS/ASOS platforms. Bulk of this precipitation looks to move through the Chicago metro by 430-530 pm, though additional more isolated to scattered showers and thunderstorms are possible into early evening as another short wave drops southeast across the Upper Mississippi Valley into tonight. Loss of diurnal instability should result in diminishing coverage by/after sunset however. Moist low levels, wet ground and light winds will likely allow for patchy fog development again tonight, especially across areas north of I-80 where heavier rainfall is likely this afternoon/early evening. The second short wave is progged to clear the forecast area by midday Wednesday. Given poor diurnal timing, have maintained only slight chance pops mid-late morning for our southeast counties, with rain potential generally decreasing by early afternoon as the upper trough axis moves east of the area. Column dries out in mid and upper levels in the afternoon in the wake of this wave, which should allow for partly/mostly sunny skies and for temps to warm into the low-mid 80s most areas, though light onshore flow will keep things just a bit cooler along Lake Michigan. Ratzer && .LONG TERM... 300 PM CDT Wednesday night through Tuesday... For Wednesday night into early next week, the GFS and ECMWF continue to be in reasonable agreement and the GEM is getting a bit more on board regarding the amplification of a longwave ridge over the western CONUS and the digging of an eastern CONUS trough, with the eventual but relatively brief development of an upper low over the local area this weekend. A short warming trend that begins Wednesday will be more pronounced on Thursday as winds turn westerly or southwesterly. By Thursday afternoon into Friday the combination of increased low level moisture, shortwave energy aloft, and the approach of a surface low out of Iowa will support periods of showers and thunderstorms, with the highest chances and greatest coverage presently appearing to be Friday afternoon across the southern half of the forecast area. There will also be a decent temperature contrast Friday afternoon, with upper 70s in areas seeing onshore flow along the lake, and mid 80s in far southern locations. Temperatures cool a bit for the weekend but shower and thunderstorm chances persist under a digging longwave trough and developing upper low. It is likely the weekend activity will be more diurnally driven given the cyclonic circulation aloft and relative lack of low level moisture or focused convergence. By Monday the aforementioned models are already starting to push the upper low away from the area and have moved the longwave trough axis to our east while also indicating the approach of a surface ridge. Given these trends the Monday afternoon period may not be dry for the entire area but overall shower coverage should be less than during the weekend. Confidence obviously decreases considerably into early next week, but early trends suggest moisture and warmth will start to work back into the area by Tuesday. Lenning && .AVIATION... For the 00Z TAFs... Main concern for the evening and overnight hours will cig/vis trends. The main area of rain has moved out of the area, but there will still be some chance for isold shra/isold tsra into the evening. The main focus for any additional pcpn will be lingering outflow boundaries and weak mid-level impulses over the area. The most well-organized outflow boundaries are south of the terminals and expect the bulk of any pcpn to remain coincident with these boundaries. However, there are a few weak mid-level impulses moving across nrn IL that could still bring some isold pcpn. given the isolated nature of any pcpn, confidence is too low to include in the TAFs at this time, except for a vcsh mention at RFD/GYY based on latest radar trends. With the winds expected to becm lgt/vrbl and continued moist low levels, in recent rainfall, fog is expected to develop across the region overnight. Latest model guidance continues to suggest that the denser and more widespread fog should be west of the Fox Valley, with RFD/DPA likely to see the lowest vis to 1/2sm or less. Have gone with a tempo 2sm at ORD/MDW, but there is the potential for lower vis at these sites as well, though confidence is lower in the potential for LIFR vis. && .MARINE... 152 pm...A weak area of low pressure will move across the southern Great Lakes region tonight as a weak area of high pressure moves across the western Great Lakes region on Wednesday. Strong low pressure will move across Hudson Bay tonight into Wednesday morning. A trailing cold front from this low will move south across the region Wednesday night with generally northerly or northeasterly winds prevailing into the weekend. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Medford OR
903 PM PDT Tue Aug 7 2018 .DISCUSSION...A minor update this evening to more precisely depict the inland movement of stratus into Coos and far western Douglas Counties into Wednesday morning. Little change to the forecast is expected with the next issuance early Wednesday morning. The major weather concerns remain unusually hot temperatures through Thursday, gusty and strong southerly winds in the Shasta Valley on Thursday (with breezy southwest winds on the east side), then the region of strongest southwest to west winds transitioning to east of the Cascades for Friday with the passage of a dry cold front. The thickness/visibility of smoke has made slight but noticeable improvement in much of the Rogue and (to a lesser extent) Klamath Valleys this evening. The HRRR model seemed to pick up on this, and shows a slow, gradual deterioration overnight into Wednesday. This variability in smokiness for the smokier areas...south of Coos and northern/central Douglas Counties is to be expected while conditions generally do remain smoky while the current pattern continues to trend hotter and drier through Thursday. Please see the previous discussion below for further details of the seven-day forecast. && .AVIATION...For the 08/00Z TAFs...Over the coastal waters, along the coast, and coastal valleys...IFR cigs persist from the waters to the coast and will spread into the coastal valleys tonight. IFR cloud cover will retreat back to the coast again by Wednesday afternoon. Over the Umpqua Basin...MVFR cigs are expected to spread inland as far as Scottsburg tonight. The remainder of the area will remain VFR through Wednesday. Over the remainder of the area...Areas of MVFR vsbys and local IFR vsbys in smoke will persist through Wednesday. && .MARINE...Updated 800 PM PDT Tuesday 07 August 2018...A thermal trough will persist near the coast with north winds and short period seas south of Cape Blanco reaching a peak this evening. Conditions are below small craft advisory levels over most of the area. The exception will be a small area between Cape Blanco and Gold Beach from 5 to 10 nm offshore that may see borderline small craft conditions through this evening. Winds and seas will be lighter Wednesday through Friday. A front will move onshore Friday then a thermal trough will strengthen behind the front. Strong north winds and choppy wind driven seas may develop Saturday afternoon and continue through Sunday. && .PREV DISCUSSION... /Issued 240 PM PDT Tue Aug 7 2018/ SHORT TERM...An upper level ridge will continue to build over the region through Wednesday, then remain in place into Thursday. This will bring hot temperatures to inland areas. Then an upper trough will move into the Pacific Northwest late Thursday and Friday. Gusty winds are expected ahead of and with the trough passage in the afternoon and evening on Thursday and Friday. On Friday temperatures will lower across inland areas. Models are in good agreement with the upper ridge building over the area and bring hot temperatures to inland locations. This is expected to bring triple digit temperatures to many inland west side valleys. Model guidance indicates temperatures heating up into the 106 to 107 range Wednesday and Thursday for Medford. However with the effects of smoke factored in, expect highs to be in the 101 to 103 range. Similar temperatures in the lower 100s are expected in other parts of the Rogue Valley as well as in the Azalea and Sunny Valley areas, Applegate Valley, Shasta Valley. Only limited relief is expected overnight for these areas with temperatures briefly lowering into the mid to upper 60s. Other inland valleys east of the Cascades, in Northern California and in the Umpqua Valley are also expected to heat up with highs rising into the 95 to 100 range. Meanwhile wildfire smoke will continue to impact inland areas. Across western valleys in Jackson and Josephine county, expect continued significant smoke impacts each day due to northwest daytime winds bringing smoke in to the valleys from area wildfires. Location east of the Cascades and over Northern California will see smoke from fires both in Oregon and California today and Wednesday. On Thursday, expect winds to become gusty out of the south to southwest with upper level winds also out of the southwest. This will bring smoke up from wildfires in California. Of concern, the gusty winds combined with low humidities may bring increased fire weather concerns on Thursday, especially to the Shasta Valley where strong winds are possible. A fire weather watch (RFWMFR) is in effect on Thursday for the Shasta Valley. For coastal areas, expect continued areas of low clouds and patchy fog overnight and in the morning today and Thursday with partial daytime clearing. On Friday, as the upper trough moves over the Pacific Northwest, a dry cold front will move inland. Winds ahead of this front for areas from the Cascades east are expected to be gusty out of the southwest with breezy west winds expected across areas west of the Cascades. This pattern will also bring a cool down with daytime temperatures lowering 10 degrees into the upper 80s to mid 90s across inland areas. Along the coast and into the Umpqua, expect relatively cooler and moister conditions with a marine push of low clouds expected along the coast and into the Umpqua Valley Friday night. LONG TERM...Saturday through Monday...The upper trough will gradually shift northeast on Saturday then a zonal westerly flow pattern sets up aloft on Sunday, transitioning to a ridge on Monday. At the surface, models indicate a thermal trough will develop along the coast by Sunday and expand north on Monday. This pattern will result in warming temperatures across inland areas Sunday into Monday. Offshore flow will bring dry easterly winds to the coastal ridges. This will also result in partially clearing skies along the coast with decreased low clouds. With the ridge remaining in place Monday into Tuesday, will need to monitor if mid level moisture and shortwaves move up from the south, which may bring a slight chance for thunderstorms. Models currently show very weak mid level moisture. So have kept thunderstorms out of the forecast. FIRE WEATHER...Updated 200 PM PDT Monday, 6 August 2018...A warming and drying trend will continue through Thursday, followed by a dry cold front passing through the area on Friday, bringing increasing winds to most areas. The air mass on Wednesday and Thursday is expected be one of the hottest for this time of year (top 10 percent). That being said, the thick smoke from the fires will prevent the hottest temperatures from being realized. A weak thermal trough pattern will deliver generally light northeasterly nighttime winds to areas of Northern California and east of the Cascades, as well as upper slopes and ridges west of the Cascades tonight. Overnight ridgetop humidity recoveries will gradually worsen and become poor to moderate over the ridges by Wednesday night (tonight through Wednesday night in areas east of the Cascades). the latest low level moisture images are showing a dry layer to the south of us that should push into the region with 700 mb winds becoming more southerly overnight. Have lowered ridge RHs tomorrow to somewhat mirror this. Model guidances suggest a slight increase in winds Wednesday, and then significant increases on Thursday and Friday. The increasing southerly general winds will impact areas east of the Cascades and in Northern California from the Shasta Valley eastward. Other areas, like the Rogue Valley and other West Side valleys will likely see enhanced afternoon winds from the typical summertime direction of northwest, especially on Friday. This increase in winds and dry cold front passage will definitely represent a significant change in fire weather environment. With the increased winds and dry weather, conditions could easily become near critical east of the Cascades as well as for the Shasta Valley--especially on Friday, but conditions could also be close on Thursday as well. Have issued a fire weather watch for the Shasta Valley on Thursday and decided to headline these conditions in the FWFMFR and FWLMFR for east of the Cascades. However, could see the possibility of a fire weather watch on Friday for over eastern areas. This will need to be monitored with the next couple forecast cycles. Models continue to show little support for thunderstorms ahead of the approaching trough on Friday. There is very little moisture per the latest operational GFS, and many model runs before this one. Confidence is increasing that the major impact from this trough will be the windy, hot, and dry conditions, and not thunderstorms. Cooler conditions on Saturday will follow the frontal passage. -Sven && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Heat Advisory from 11 AM Wednesday to 9 PM PDT Thursday for ORZ023-024-026. CA...Fire Weather Watch from Thursday afternoon through Thursday evening for CAZ281. Heat Advisory from 11 AM Wednesday to 9 PM PDT Thursday for CAZ081. Pacific Coastal Waters...None. $$ DW/NSK
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1046 PM CDT Tue Aug 7 2018 .UPDATE... Issued at 1046 PM CDT Tue Aug 7 2018 Updated to include 06Z aviation discussion below. && .SHORT TERM...(This evening through Wednesday) Issued at 301 PM CDT Tue Aug 7 2018 The main short term concerns remain timing of convection into the evening and again to the east into Wednesday afternoon. Latest SPC mesoanalysis showing 1000 J/kg MLCAPE and weak surface boundary working over west central WI. Satellite showing upper circulation weakening but still evident working very slowly east over south central MN. Able to regenerate some convection under the low central. Otherwise, widely scattered convection over mainly west central WI with some isolated land spout reported up in Burnett Co region. We`ve also gotten several reports of funnel clouds in central MN (near the Hector-Hutchinson areas). Convection follows southwest into east central MN(Chisago and Polk Co Wi). Mesoanalysis still showing some surface vorticity along the boundary and enough low level CAPE to continue the landspout threat a couple more hours. Forecast trend on the SPC meso site does weaken this by late afternoon. Not certain on overall timing of ending the PoP chances to the southeast. HRRR trends has been slowing the movement into west central WI. Will hold onto slight chance through about 02z for now. Clouds may linger much of the night to the east, at least high level clouds. This may limit overall fog threat but still will likely see some patchy fog where clouds thin/clear the most. Have included patchy/areas fog over the eastern area late. Expect temperatures to warm through the 80s Wednesday afternoon and both he GFS and ECMWF bring down a weak short wave trough and surface boundary and generate some light QPF from St Croix River east into WI Wednesday afternoon, Does look pretty unstable with MUCAPES over 1750 J/kg, best LI`s around minus 7 and bulk shear around 35 kts off the GFS. DAY2 SPC outlook was updated to include marginal risk for severe. Will have to monitor timing of boundary and overall strength of destabilization for that period. .LONG TERM...(Wednesday night through Tuesday) Issued at 301 PM CDT Tue Aug 7 2018 Wednesday night through Sunday...A cold front with limited moisture will drop through the MN/WI region Wednesday night into Thursday morning and will continue to drift south during the day Thursday. While this will result in the end of any lingering showers over interior western Wisconsin Wednesday night followed by dry weather for Thursday, it will not result in any significant cooling. Upper level ridging over the southwestern CONUS will take a NE-SW orientation and spread into the Northern Plains Friday then into the Upper Mississippi River Valley region over the weekend. Meanwhile, the surface front to the south will gradually wash out and dissipate. The net result of the surface and aloft features will be a continuation of above-normal warm temperatures through the weekend and dry conditions. Dewpoints will remain in the low-mid 60s so in peak heating, heat index values will climb to near 90 each day through the weekend. Monday through Tuesday...For the early portion of next week, the upper level ridge will break down to a more zonal pattern while a cold front slowly approaches from the west. While this will maintain the warm and humid conditions, this scenario will also force the inclusion of chance PoPs into the forecast. Not looking for anything strong but there will be several periods of scattered showers/thunderstorms going into the mid-August period. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1046 PM CDT Tue Aug 7 2018 Shortwave trough currently moving through South Dakota could bring some SCT and perhaps briefly BKN VFR clouds across the southern half of the area Tuesday morning, but otherwise things look to be mostly clear across most of the area through the period. The exception looks to be over the east, where some fog could occur later tonight, and where there is a possibility of some SHRA/TSRA late Wednesday afternoon or early evening as a shortwave trough drops southeast from Canada into the area. A few of the CAMs suggest activity may pop up over northeast Minnesota and northwest Wisconsin during the mid to late afternoon and potentially move near KRNH or KEAU thereafter. However, there hasn`t been consistent agreement on this scenario, and confidence is too low at this point to include a mention. But, will bear watching in subsequent forecasts. The fog overnight seems to be somewhat more likely, particularly at KEAU where there was some rain nearby today. KMSP...Will have some southerly winds in the morning hours, but should generally be below 10 kt, and look to veer more westerly by afternoon. May also see some SCT-BKN clouds AOA 5k ft late afternoon or evening depending on what`s able to develop to the north and drop southeast. For now any of that looks to stay east of the area, so stayed optimistic and left out any mention. /OUTLOOK FOR KMSP/ Thursday and Thursday night...VFR. Northeast/north wind 5 kt or less. Friday through Saturday...VFR. Variable wind less than 5 kt. Saturday night...VFR. South wind 5 kt or less. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ UPDATE... SHORT TERM...DWE LONG TERM...JPC AVIATION...
Area Forecast Discussion
National Weather Service San Francisco Bay Area
901 PM PDT Tue Aug 7 2018 .SYNOPSIS...Strong high pressure over the western United States will maintain warm to hot conditions across inland areas through the end of the work week. Along the coast temperatures will be seasonably mild as a shallow marine layer and moderate onshore flow prevail. Temperatures may be impacted through the week as wildfire smoke spreads across the region from time to time. && .DISCUSSION...As of 9:00 PM PDT Tuesday...High temperatures today were as much as 15 degrees cooler compared to Monday. Today`s cooling was the result of a number of factors including an increase in the depth of the marine layer and a slight increase in the strength of onshore flow - both triggered by a weak shortwave trough moving across northern California. Another contributing factor to today`s cooling was decreased solar insolation due to a thick layer of wildfire smoke aloft. Based on the most recent HRRR smoke model data, smoke will linger across our region at least into Wednesday. Most smoke is expected to remain aloft, but some areas will experience smoky conditions near the surface, primarily in the North Bay. An upper level ridge dominating the western third of the nation is forecast to build more strongly over California during the next few days. This is expected to result in warmer temperatures, especially inland, through Thursday. However, continued smoky skies may reduce the amount of expected warming by at least a few degrees. A deep upper low, currently centered several hundred miles off the West Coast, is forecast to move to the ENE later in the week and inland across the Pacific Northwest by late Friday or Friday night. This is expected to result in 5 to 10 degrees of cooling inland over the coming weekend. Hurricane John, currently off the west coast of Mexico, is forecast to drift to the northwest off the coast of Baja through the end of the week. The models agree that moisture from John will be drawn northward by southerly flow aloft and make its way across portions of our forecast area by Thursday night or Friday. The 12Z run of the NAM indicated scattered precipitation and possible thunderstorms across the North Bay on Friday morning. However, the subsequent 18Z and 00Z runs of the NAM no longer show convective precipitation over our area. However, the NAM does continue to show increased mid/upper level moisture and instability across the Bay Area late Thursday night through Friday which potentially could mean high-based thunderstorm development. The latest GFS and ECMWF do not forecast as much mid/upper level moisture and instability as the NAM and so forecast confidence is not yet high enough to explicitly add thunderstorm chances to the forecast late in the week. Thunderstorm potential in our area may not be limited to Friday. The models indicate mid and upper level moisture will increase once again by late in the weekend and into early next week. Will continue to closely monitor this influx of tropical moisture during the extended forecast period and look for any potential for lightning (see fire weather discussion below). && of 5:20 PM PDT Tuesday...More widespread smoke seen today with a reduction in slant range visibilities and occasionally MVFR visibilities tonight through Wednesday. A positive 24 hour trend in surface dewpoint temperatures with a slightly deeper marine layer seen on the profiler data, marine layer is near 1,200 feet deep except shallower at approx 500 feet at the Point Sur profiler. Onshore winds will usher stratus and fog inland tonight and Wednesday morning. Clearing returning by late Wednesday morning. Vicinity of KSFO...VFR with gusty westerly wind this evening. Less wind tonight and Wednesday morning. IFR cig is forecast 09z-17z. SFO Bridge Approach...Similar to KSFO Monterey Bay Terminals...LIFR/IFR cigs return early this evening. Clearing returning by late Wednesday morning. && .MARINE...As of 8:42 PM PDT Tuesday...Gusty northwesterly winds will steadily weaken through mid week. Long period southerly swell will arrive later Thursday originating from Hurricane John off the Mexico/Baja California coast, swell will mainly affect the outer coastal waters. && .FIRE WEATHER...As of 8:55 PM PDT Tuesday...The 12z nam showed some possible t-storms on Friday morning across the North Bay as tropical moisture moves in from the SSW. Both the 18Z and 00Z NAM forecast a similar evolution of moisture but are not as bullish at producing precipitation. Modified Total Totals with the NAM are greater than 30 across the Bay Area on Friday, and this mid level instability is paired with a good slug mid level moisture. However, the GFS and ECMWF are less robust with both moisture and instability compared to the NAM. Will continue to monitor these trends over the next day or so for possible impacts to the Bay Area and points northward (Mendocino Complex). Even wet storms would be problematic if down strikes occur on dry fuel beds. For now confidence is not high enough to explicitly put thunderstorms in forecast. Forecast only includes some low 10 percent POPS as a starting point. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM SCA...Pt Arena to Pt Reyes 0-10 nm && $$ PUBLIC FORECAST: Dykema AVIATION: Canepa MARINE: Canepa FIRE WEATHER: RWW/Dykema Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Nashville TN
855 PM CDT Tue Aug 7 2018 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... A few ongoing showers and thunderstorms are ongoing along the KY border east of I-65, and look to continue eastward. Models are consistently showing another round of showers and storms moving in before sunrise associated with the upper shortwave, so adjusted pops accordingly. It looks like the majority of the rainfall potential will be just after sunrise through the early afternoon across the mid state, and lines up pretty well with existing forecast thinking. The HRRR and NAM do bring in some isolated convection during the overnight hours earlier than other models, but overall CAM consensus confines the activity to the northwest zones before sunrise, and spreading east and south after sunrise. Other than the usual adjustments to temps and dewpoints to match up with obs trends, rest of the forecast is on track. && .AVIATION... 00Z TAF DISCUSSION. VFR. VCSH will affect CKV and possibly CSV early this evening, but otherwise dry conditions are anticipated until Wednesday morning when most models show additional scattered showers and storms. South to west winds are expected through the TAF period. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Barnwell AVIATION........Shamburger
Area Forecast Discussion
National Weather Service Portland OR
238 PM PDT Tue Aug 7 2018 .SYNOPSIS...High pressure will maintain warm conditions through Thursday, along with hazy skies thanks to smoke from California and sw Oregon. Clouds along the coast and light onshore winds will maintain cooler conditions for the coast. An upper low will pass to our north Friday and Saturday for cloudier and cooler weather, and possibly light rain. && .SHORT TERM...Today through Friday...The main forecast challenge with the short term forecast is determining how hot the next several days be east of the coast range. Model guidance and weather pattern recognition indicates that it will be very hot, but these sources do not take smoke or haze (from wildfire smoke) into consideration. Forecasting the thickness of smoke not our expertise, but has the potential to have a great impact on surface temperatures. The trend of late is for the haze to be fairly thin or unnoticeable in the morning and early afternoon and become more noticeable in the late afternoon and evening (except or the Lane County Cascades where the haze has been persistent). Satellite imagery shows a really light haze over the forecast area now with a thicker haze layer over the Cascades of Lane County slowly moving NNW. The hrrr forecasts this haze to become more widespread across NW Oregon and likely over the Willamette Valley late this afternoon and early evening, which supports the observed trend the past couple of days. If the haze is thin, and allows for a lot of solar radiation to make it to the surface, then the modeled 850mb temperatures of 21 to 24 degC would allow the afternoons to peak in the upper 90s to low 100s Wednesday and Thursday. Otherwise, if haze from smoke is similar to as it was yesterday (Monday) evening, then the temperatures will likely be in the mid to upper 90s. Both of these scenarios will provide hot weather and lead to potential heat stress.And the nighttime temperature relief will be slow with temperatures lingering in the 70s until 1 or 2 in the morning. Another adding factor to the discomfort of this heat is that 700-500mb south winds will allow for higher dew points, and a muggier feeling to the heat. This increases the heat index and will allow the temperatures to feel warmer than they actually are. Will continue the Warnings and Advisories for heat due to the potential impacts. Temperatures at the coast will be much cooler as weak onshore flow and nocturnal marine clouds will keep the afternoon temperatures in the upper 60s to mid 70s. An upper low that will linger well offshore the next few days will approach the coast Thursday and begin to move over the region Thursday night. This will increase onshore winds in the afternoon and favor a deeper southwest marine push Thursday night into Friday. Models indicate instability over the Cascades Thursday afternoon and evening as upper level divergence ahead of the upper low moves over the region. Modeled precipitation water values increase to around an inch at this time too. The increase of mid-level moisture and instability suggests that afternoon and possibly nocturnal convection may be possible. Have not added any thunderstorms to the forecast though as the increasing onshore winds would likely keep any developing storms at the Cascade crest or east of it. The threat for Cascade thunderstorms Thursday afternoon and evening is not 0, but not over 10 percent either. Will re-evaluate this threat tomorrow and Wednesday as the time period gets in the time range of the higher resolution models. The upper level trough and low will move over the region Friday for cloudier and cooler weather. Light rain is possible for the coast Friday afternoon and possibly inland Friday night. The interior temperatures will be closer to the seasonal normals Friday afternoon (low 80s). ~TJ .LONG TERM...Friday night through Monday. Light rain is possible Friday night and Saturday as an upper trough moves over the area. Any accumulating rain will most likely be over the higher terrain and north of Salem. High pressure returns to the surface Sunday, but a weak upper low should maintain some coastal marine clouds and onshore flow. An upper ridge returns for Monday for less clouds and afternoon temperatures possibly getting back into the low 90s. ~TJ && .AVIATION...IFR stratus continues along the central Oregon coast this afternoon, with little change expected through the next 24 hours. Expect that low stratus will again return to the remainder of the coast and the valleys of the Coast Range late this evening, with some shallow stratus along the lowest reaches of the Columbia River as far as KKLS. Across the remainder of the interior, VFR conditions expected to continue through the TAF period with an elevated smoke layer at around 8000 feet. KPDX AND APPROACHES...VFR conditions continue through next 24 hours. Elevated smoke from wildfires will remain at around 8000 feet. Cullen && .MARINE...Weak surface high pressure will remain near or over the waters for the first half of the week. The surface pressure gradient will strengthen today as the low pressure inland intensifies and the surface high tilts inland across southern Washington, with low-end advisory strength gusts across the northern zones, but only occasional gusts to this strength south of Cascade Head. A large low pressure system currently spinning near 140W will eventually move into the Pacific Northwest Friday or Saturday, bringing a time of gusty southerly winds to the waters. Seas will remain 4 to 6 feet through most of the week. Cullen && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning until 11 PM PDT Thursday for Central Columbia River Gorge-Central Willamette Valley-Greater Portland Metro Area-Upper Hood River Valley-Western Columbia River Gorge. Heat Advisory until 11 PM PDT Thursday for Cascade Foothills in Lane County-Lower Columbia-Northern Oregon Cascade Foothills-South Willamette Valley. WA...Excessive Heat Warning until 11 PM PDT Thursday for Central Columbia River Gorge-Greater Vancouver Area-Western Columbia River Gorge. Heat Advisory until 11 PM PDT Thursday for I-5 Corridor in Cowlitz County-South Washington Cascade Foothills-South Washington Cascades. PZ...Small Craft Advisory for winds until 9 PM PDT this evening for Coastal Waters from Cape Shoalwater WA to Cascade Head OR out 60 NM. && $$ Interact with us via social media: This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. This area is commonly referred to as the CWA or forecast area.
Area Forecast Discussion
National Weather Service Pueblo CO
913 PM MDT Tue Aug 7 2018 .UPDATE... Issued at 908 PM MDT Tue Aug 7 2018 Updated the fcst to expire severe weather watch and adjust flash flood watch. As posted on NWS CHAT and Twitter, I am still concerned isolated severe storms will affect the region this evening and tonight. As I write, convection was beginning to initiate over several locations of the plains. This convection is likely elevated, but the shear is still quite strong (40-50 knts) and the MLCAPE values are still rather high (1500-2500) per SPC mesoanalysis page. Locally heavy rain is still possible, with best chances southof US50. /Hodanish UPDATE Issued at 647 PM MDT Tue Aug 7 2018 Short range hi res guidance is having a difficult time handling the current wx situation over the region at this time. Except for a TSRA over Custer county, no other significant convection was noted over the region at 645 pm. Guidance insist that strong convection should be occurring over parts of the plains attm. What I believe is the issue is a short wave ridge is moving over SE Colo attm and this is suppressing convection. A rather strong short wave is fcst to begin affecting the region late this evening and tonight, and we may have a better chance of storms over the plains late this evening/overnite. For now have trended POPS downward but I am keeping the convective/flooding hilites in place. Any small storm over a burn scar could cause flash flooding. /Hodanish && .SHORT TERM...(This evening through Wednesday) Issued at 203 PM MDT Tue Aug 7 2018 Forecast models continue to show showers/tstms over the eastern mtns and along the I-25 corridor early this evening, and then as an upper level disturbance moves southeast acrs the eastern portions of the state, the storms will spread acrs the plains thru the late evening. The western mtns and high valleys are still expected to see a lower risk of showers/tstms this evening. With abundant moisture over the area today, heavy rain remains a threat thru the evening and into the late night hours in some locations, and could present a flash flood risk for urban areas, burn scars over eastern areas, and in areas where heavy rain fell yesterday. There also continues to be the risk of a few severe storms over the southeast plains this evening and a Severe Thunderstorm Watch is in effect until 9 PM MDT. The NAM shows some lingering precip over the far southeast plains into the late night/early morning hours. The GFS does the same, but also shows some light lingering precip over and near some of the eastern mtns. The HRRR shows some light linger precip over Baca county thru about 09-10Z, and dry conditions elsewhere. Have decided to carry some low POPs thru about 11Z over mainly the far southeast plains. There will still be ample moisture over the area on Wed. It looks like storms will initiate around Noon over the eastern mtns and move off over portions of the I-25 corridor. The storms are not expected to spread acrs the southeast plains until the evening hours. Conditions will again be favorable for a few severe storms over the plains. .LONG TERM...(Wednesday night through Tuesday) Issued at 203 PM MDT Tue Aug 7 2018 There is continued low spreads among the ensemble members through the extended, with some spread as we get into Monday and Tuesday next week. Operational solutions remain similar leading to higher confidence through at least the weekend. Wednesday night into Thursday...high pressure will remain centered over Nevada with disturbances rotating south across Colorado Wednesday night into Thursday. Expect widespread showers and thunderstorms across the Eastern Mountains, spreading east into the I-25 corridor, then south and east overnight. Locally heavy rainfall will remain possible with flash flooding on area burn scars, urban areas and locations that have seen heavy rains the past couple of days. In addition, one or two storms could become strong to severe as they move across the Plains with large hail and damaging winds the main threats. This activity will shift south into New Mexico late Wednesday night into Thursday morning. Models are slightly different on Thursday. The NAM has one last upper wave rotating around the high to the west, dropping south across Colorado. The GFS does not, confining shower and thunderstorm activity to the Continental Divide. Given the uncertainty, will continue with POPs across the mountain areas, spreading east into the I-25 corridor through the evening hours. Expect this activity to shift southward into New Mexico by late evening. Friday into Monday...the high pressure over the west is forecast to shift east and north with northeasterly flow setting up across the region. Expect showers and thunderstorms to become more diurnally and terrain driven Friday and through the weekend. Initial development will occur over the mountains, primarily along the Continental Divide. Activity will then spread southwest into New Mexico during the evening or dissipate after sunset. Locally heavy rainfall will remain possible, especially over the San Juan range. Tuesday...there are slight differences in the operational solutions. The GFS shifts the high pressure westward, while an upper disturbances drops southeast across Colorado with a return to widespread showers and thunderstorms across the area. The ECMWF has a similar upper disturbance, but much further north. It also tries to bring a disturbance up from the south which the GFS does not have. Mozley && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 203 PM MDT Tue Aug 7 2018 KCOS and KPUB could see thunderstorms in the vicinity thru the evening, with heavy rain being a threat. Some hail may also occur with stronger storms. By the late night hours, the threat of storms should end, but there is the possibility of some low stratus developing. KALS is expected to have VFR conditions thru the 24 hrs period. && .PUB WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until midnight MDT tonight for COZ072>075- 078>080-087-088-094. && $$ UPDATE...HODANISH SHORT TERM...28 LONG TERM...MOZLEY AVIATION...28