Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/06/18

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
650 PM CDT Sun Aug 5 2018 .AVIATION... For the 00Z TAFs, isold to sct showers and tstms over sern CO and nern NM will track east this evening and could graze the western and central OK Panhandle with a very small threat that KGUY could be impacted. Have omitted mention of this weather element at this time due to very low confidence. Will closely monitor radar trends this evening. Otherwise, VFR conditions are anticipated at the TAF sites through late Monday afternoon. Showers and thunderstorms are then forecast to move southeast into the region after 00Z Tuesday, which is just beyond this fcst cycle. Andrade && .PREV DISCUSSION... /Issued 346 PM CDT Sun Aug 5 2018/ DISCUSSION... Storms are already popping up in New Mexico and Colorado. Storms are expected to make it to the Oklahoma Panhandle between 7 and 9 PM tonight. The HRRR was tracking pops relatively well so went with that guidance on pops for the night. Not much CAPE to work with, but decent DCAPE exists, so could see wind gusts to 50 mph out of a good storm. Going into the beginning of the work week, a cold front gets close to the area and brings chances for precip as it interacts with a mid-level shortwave riding around the rim of the upper level high pressure bubble. With 2500 J/kg of CAPE and 1000 J/kg of DCAPE, which is up from yesterday`s models forecast, damaging winds and hail up to quarters could be possible. PWATs are forecast around 1.5 in which is well above the 90th percentile and near the maximum average. Thus storms could have localized flooding concerns as well. Models today were stalling out the front slightly further north than yesterday, placing it more in the northern Texas Panhandle than in the mid to southern TX Panhandle. Depending on where this boundary sets up and any left over outflow boundaries, Tuesday could have some interesting chances for severe weather as well. CAPE and DCAPE are forecast to be even more than Monday, with good turning in the low layers. Also, shear increases to near 25-30 kts. While Wednesday also has decent values for severe weather, the atmosphere may be so worked over by then that it may limit the storm potential. It is really going to be dependent on boundaries and where storms have been. The early part of the week definitely bears watching. The end of the week is a little more tricky. Models begin to diverge on solutions, but the area looks to be in northeast flow aloft, which is generally drier for us. There have been cases in the past where we did have storms with this flow pattern, but for now have followed the downward trend of drying out the weekend. Beat && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$
Area Forecast Discussion
National Weather Service La Crosse WI
642 PM CDT Sun Aug 5 2018 .SHORT TERM...(This evening through Monday) Issued at 245 PM CDT Sun Aug 5 2018 Primary forecast focus is on severe/heavy rain threats through Monday. Quasizonal flow aloft was inferred from water vapor imagery early this afternoon across the Upper MS Valley with several embedded shortwaves in the flow. At the surface, a cold front was draped across central MN southwestward. The forecast remains quite challenging through the evening as models have struggled over the past few days with convective trends in a weakly forced environment. Overall, a bit less impressed by severe potential through the evening. Weak mid-level height rises are expected through late afternoon before a shortwave trough approaches from the west by early evening. Convection crossing IA during the morning could also impact ultimate convective evolution although many of the CAMs struggled to capture the early morning convection. Recent runs of the RAP have backed off on instability a bit, with pockets of 1000 to maybe 2000 J/kg of MLCAPE within a low-level confluent axis ahead of the approaching front. With the exception of across northern Wisconsin, deep layer shear remains fairly modest through the afternoon (~30 kts) before somewhat stronger mid-level flow overspreads the area from the southwest during the evening. Isolated to scattered showers/storms are possible this afternoon and early evening, including along outflow boundaries. Confidence isn`t very high on the coverage or placement of storms, especially with limited upper forcing. Despite the marginal shear and somewhat lower instability, still could not rule out a few strong to severe storms going into the evening. As deeper forcing and low-level convergence/moisture transport continue to increase through the evening and overnight ahead of an upper wave, expect convective coverage to increase during the late evening and overnight. With CAPE gradually eroding through the evening, any severe threat still is expected to transition to more of a heavy rain threat given a favorably deep, warm and moist environment. The preferred area for heavy rainfall looks to be south of I-90 overnight. 1 to 2 inches of rain is possible, although with potentially locally higher amounts. With relatively dry antecedent conditions, would not expect any widespread hydro issues, but will have to watch for any localized high rainfall totals. The threat for any severe weather continues to appear low on Monday with widespread clouds and rain likely keeping stronger instability south of the area as the frontal boundary slips southward. Would expect the stronger moisture transport to slide south and east with the front. However, with shortwave energy continuing to cascade through the flow, showers and storms will remain possible Monday into Monday evening, likely decreasing in overall coverage through the day. .LONG TERM...(Monday night through Sunday) Issued at 245 PM CDT Sun Aug 5 2018 Low precip chances may continue into Tuesday as another shortwave digs across the area. Otherwise, an extended generally quiet period of weather is expected during this time. Northwest flow aloft will continue through late week with high pressure at the surface. A weak surface boundary may slip into the area by Thursday with a low chance for convection. Overall, rain chances are low through the weekend. Upper ridging may build east into the area towards the weekend with some models developing a closed low southeast of the area. Generally seasonable temps in the 80s are expected through mid and late week. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 642 PM CDT Sun Aug 5 2018 Watching an area of mainly showers stretching from southeast SD eastward along the MN/IA border. Near-term environment is not conducive for thunderstorms so removed thunder mention from TAFs. That said, periods of showers are likely and could see some temporary reductions in visibility with heavier rates. An isolated gust to around 25 kts is also possible. Thunder chances increase overnight, but confidence not high given current observational trends. Will amend for thunder as necessary. Rain looks to end by mid-Monday morning with VFR conditions thereafter. Light southwest wind will be the rule, eventually shifting to the northwest Monday afternoon. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...JM LONG TERM...JM AVIATION...Rogers
Area Forecast Discussion
National Weather Service Bismarck ND
1006 PM CDT Sun Aug 5 2018 .UPDATE... Issued at 1006 PM CDT Sun Aug 5 2018 Multicellular convection from northwestern ND into northeastern MT appears to be associated with a slightly stronger impulse aloft based on earlier surface pressure falls focused in that area, and recent observed propagation is directed southeastward along a weak weak low- and midlevel frontal zone that extends from near Sidney, MT, to Beulah and Jamestown, ND, as of 02 UTC. Weak frontogenesis near that frontal zone and modest mass field responses aloft with the approaching weak shortwave trough impulse will likely aide in the continued east-southeast propagation and maintenance of that area of showers and a few thunderstorms through the night, so we used this update cycle to modify PoPs in line with that thinking, spreading 40-50 percent probabilities into central ND after 05 UTC. The 00 UTC Bismarck RAOB captured multiple weak inversion layers aloft and midlevel lapse rates around 6.5 C/km, and recent KBIS and KMBX WSR-88D VWP data shows 0-6-km bulk wind differences only around 20 kt in further support of multicellular convection. Given locally amalgamating cold pools and residual steep low- level lapse rates, a few strong storms -- possibly with both gusty winds and some hail -- could occur in west central ND the next 90 minutes, but the overall risk of strong storms overnight will be minimized by the lack of stronger instability and weak shear. Note too that the lack of an appreciable low-level jet will further hinder any notable theta-e response, tempering instability, and negating any discernible improvement in shear profiles, as well. UPDATE Issued at 706 PM CDT Sun Aug 5 2018 Little in the way of change was made with this update other than to accommodate recent observational trends. Scattered convection is ongoing early this evening, but is loosely focused along and slightly to the cool side of a weak frontal zone extending from near Rugby to Minot and Crosby per trends in GOES-16 images that have shown more agitated cumulus in that vicinity during the last few hours. Background ascent is modest -- though perhaps is a bit more notable in northeastern MT per surface pressure falls, which is likely reflective of an approaching impulse that should tend to maintain at least a low-end chance of precipitation overnight as it moves eastward. Another weak impulse is moving into western SD. This scenario justifies an increasingly broad-brush approach to the PoP forecast further from the near-term when extrapolation of observational trends is appropriate. Mid-level lapse rates are on the order of 6 C/km over most of the area, and surface dewpoints are generally in the lower to middle 50s F save for the southern James River valley, limiting instability and potential strength of any storms. Recent 0-6-km bulk wind differences from the KBIS VWP are also on the order of 20 kt, further suggesting that any storms will likely have limited intensity, although a belt of slightly stronger flow with 0-6-km bulk wind differences on the order of 30 kt may exist along the Highway 200 corridor per RAP analyses, in support of a low-end probability of stronger storms in that area. && .SHORT TERM...(This evening through Monday) Issued at 143 PM CDT Sun Aug 5 2018 Latest water vapor imagery indicates a weak shortwave trough located over southern Alberta/Saskatchewan and a couple of shortwaves ejecting east from Wyoming. The northern stream trough is forecast to slowly sag south through Monday, somewhat merging in time and space with the aforementioned shortwaves in Wyoming as they shift east. In doing so, low level cooling per a surface to 850mb cold front on the NAM/GFS will shift a cold front from north to south overnight into Monday morning. This will result in cooler air with highs in the 70s Monday as well as generate the chance for showers/thunderstorms this afternoon through Monday. Difficult to pinpoint exact areas, but it would appear the north, southwest and far south central may be more prone to the highest chances based on the above thinking. Severe weather is not expected at this time. Lows tonight will mostly be in the 50s, with lower 60s south central. .LONG TERM...(Monday night through Sunday) Issued at 143 PM CDT Sun Aug 5 2018 Large upper ridge across the west will expand north and east with time and envelop the northern high plains Tuesday through Saturday. This will result in dry, along with warm to hot conditions,as highs will range from the upper 80s to lower/middle 90s during this time period. Differences arise late next weekend, as the GFS advertises a cold front moving through Sunday/Sunday night, while the ECMWF is slower and keeps the region warm and dry through Monday night. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 1006 PM CDT Sun Aug 5 2018 VFR conditions will generally prevail through the 00 UTC TAF cycle. However, scattered showers and a few thunderstorms will move from northwest and west central ND late this evening into the central parts of the state overnight. Radar trends could necessitate amendments or adjustments with the 06 UTC TAFs to reflect higher confidence in impacts at some terminals. Localized sub-VFR conditions are possible with any storms. Otherwise, there will remain a chance of showers and thunderstorms over southern areas through Monday in association with a weak frontal passage. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CJS SHORT TERM...KS LONG TERM...KS AVIATION...CJS
Area Forecast Discussion
National Weather Service Boston/Norton MA
1003 PM EDT Sun Aug 5 2018 .SYNOPSIS... Hot and humid weather returns this week as high pressure becomes centered off the East Coast. Scattered showers and thunderstorms are possible Tuesday through Thursday, with a possible return of showers and thunderstorms next weekend. && .NEAR TERM /THROUGH MONDAY/... 10pm update... Minor changes as the previous forecast remains on track. Fog is still possible this evening, especially across the northern Connecticut River Valley as both the HRRR and the NARRE show high probabilities of visibility less than 4 miles. Guidance is not as consistent with fog on Nantucket this evening, however given the latest dewpoints, light onshore winds, and a weak inversion aloft, fog still remains possible. Previous discussion... Forecast patchy dense fog across the Mid-CT River Valley and other interior locations, possibly Nantucket as well. With light winds and clear conditions, radiational cooling proceeding overnight. Dewpoints remain high as most of S New England remains saturated from recent rains. A blend of fogger tools and near-term high- res guidance, likely pockets of interior dense fog, thinking the shallow ground type. Meanwhile off the coast of Nantucket, a low cloud / fog deck lingers. Winds have already dropped as has the dewpoint depression. Will be evaluating this area closely with respect to any low cloud / fog expansion over the island. The bulk of the guidance surprisingly keeps it quiet and dry with milder conditions. Looking at lows around the mid to upper 60s across the interior, some lower spots, while around 70 over the S-coast and urban centers. && .SHORT TERM /MONDAY NIGHT/... * Heat Advisories being issued for most of SNE * Main concern is return of heat and humidity Monday. 12z models and ensembles continue to point toward highs in low to mid 90s across much of interior, and with dewpoints around 70, heat index values peak between 95 and 100 degrees. We are issuing Heat Advisories for all but Cape Cod, Islands, and Newport and Bristol Counties in RI where onshore winds will keep it slightly cooler and heat index values should peak closer to 90. Advisories will continue into Tuesday based upon criteria of two consecutive days with a heat index of 95 degrees or higher. Otherwise expect some diurnal clouds once again but dry weather with upper ridge in place. May have short-lived sea breeze along E MA coast midday Monday before increasing S/SW flow gets underway as high pressure settles offshore. SW flow Monday night means a warm and humid night, as well as low clouds/fog near South Coast, Cape Cod, and Islands. && .LONG TERM /TUESDAY THROUGH SUNDAY/... */ Highlights... - Hot and humid conditions for Tuesday, possibly Wednesday - Shower / thunderstorm activity Wednesday night - Thursday - Warm and dry late week - Possible return of showers / thunderstorms for the weekend */ Overview... Warm days, mild nights. General H5 trof pattern maintained by up- stream N-Central Pacific to SW CONUS H5 ridge-trof-ridge pattern amplification. Against the SE CONUS Atlantic tropical ridge, W/SW continental-tropical airmass maintains, continuously pumping warm, moist air N/E towards the St. Lawrence valley up against a series of individual disturbances dipping S through aforementioned trof. While absent anomalous precipitable waters / pure tropical air cut-off by the SE CONUS ridge, still looking at shower / thunderstorm chances with an excessive rainfall risk by midweek into the weekend along frontal boundaries becoming diffuse up against the ridge / higher heights. That being said, drier air seemingly ushers in behind any frontal boundaries, perhaps some relief if trof disturbances can really dig in against the ridge, the boundary layer becoming well mixed, otherwise humidity hangs around with near to warmer-than average conditions, any nudge upon which should yield showers and thunderstorms, possibly again this weekend. */ Targets of Opportunity... Tuesday will be hot and humid with heat indices at or above 100. H85 +17-18C air well-mixed yielding highs in the upper 80s to low 90s. Can`t rule out some locations reporting highs around the mid 90s. SW flow which climatologically given the interior fetch yields warmer temperatures in and around the Merrimack River Valley and Boston- metro given the urban environment. Likely here we`ll see highs up around the mid 90s with heat indices above 100 as dewpoints will be near 70. A slight change to the airmass Wednesday, however clouds from upstream convection may limit greater daytime heating. We`ll have to watch closely as to whether we`ll see a repeat of Tuesday requiring a continuation of heat-related headlines. Watch closely the Wednesday night into Thursday timeframe. As noted by the prior forecaster, favorable jet dynamics N/W above decent low- level forcing and instability. Likely shower / thunderstorm activity upstream over NY / PA, have to watch evolution into NW S New England towards evening, then going into Thursday with frontal passage. Can not rule out heavy rain / flood impacts especially N/W, the region well-saturated from earlier rains, streamflows well-above average, urban issues always anticipated if you can throw down a quick 1-2". Possibly watch as to whether any moisture is usurped from the sub- tropical axis off the Mid-Atlantic. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/...High confidence. Tonight... IFR-LIFR dense FG concerns within the mid-CT River Valley as well as possibly out over ACK. Otherwise light winds, SKC. Monday... Increasing S/SW flow, however weak enough to allow for possible E-coastal sea-breezes mid to late morning. SCT CIGs around 3-4 kft. Monday night... Lowering conditions MVFR-IFR especially along the coast beginning by evening. Continued S/SW flow. KBOS Terminal...High confidence in TAF, although E/SE sea breeze possible 15z-18z Monday before winds veer to S/SW. KBDL Terminal...High confidence in TAF. Outlook /Tuesday through Friday/... Tuesday: Mainly VFR, with local MVFR possible. Breezy. Slight chance SHRA, isolated TSRA. Tuesday Night: VFR. Slight chance SHRA, isolated TSRA. Wednesday through Thursday: VFR. Chance SHRA, chance TSRA. Thursday Night: VFR. Slight chance SHRA, slight chance TSRA. Friday: VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/...High confidence. High pressure over waters tonight heads offshore Monday and Monday night with prevailing S/SW flow. Winds near shore should gust to around 20 kt Monday afternoon, mainly on south coastal near shore waters, along with potential for choppy 2-3 ft seas. Areas of dense fog expected Monday night on south coastal waters. Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers, isolated thunderstorms. Wednesday through Thursday: Winds less than 25 kt. Chance of rain showers, chance of thunderstorms. Thursday Night: Winds less than 25 kt. Slight chance of rain showers, slight chance of thunderstorms. Friday: Winds less than 25 kt. && .CLIMATE... Record Highs: Monday August 6 BOS 97 in 1931 BDL 95 in 2001 PVD 96 in 1918 ORH 93 in 1906 Tuesday August 7 BOS 98 in 1924 BDL 100 in 1918 PVD 95 in 2001 ORH 94 in 1924 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Heat Advisory from 11 AM Monday to 8 PM EDT Tuesday for CTZ002>004. MA...Heat Advisory from 11 AM Monday to 8 PM EDT Tuesday for MAZ002>021-026. RI...Air Quality Alert from 11 AM to 11 PM EDT Monday for RIZ001>008. Heat Advisory from 11 AM Monday to 8 PM EDT Tuesday for RIZ001>004-006. MARINE...None. && $$ SYNOPSIS...Sipprell/JWD NEAR TERM...Sipprell/Correia SHORT TERM...JWD LONG TERM...Sipprell AVIATION...Sipprell/JWD MARINE...Sipprell/JWD CLIMATE...
Area Forecast Discussion
National Weather Service Glasgow MT
839 PM MDT Sun Aug 5 2018 .DISCUSSION... Evening Update... Showers and storms developed late this afternoon and this evening, mainly along a southeastward-moving outflow boundary pushed out by earlier convection. There have been nearly zero reports from this, but radar indicated very heavy rainfall under the strongest cores. Would not be surprised to learn that those locations may have received one to over two inches of rainfall in brief periods of time. There is some concern of possibly some localized flooding along the gravel roads leading to recreation areas along Fort Peck Lake, so we issued a Flood Advisory until 10 PM this evening. Expectations are that the convective nature of these storms will rapidly dissipate over the next hour or two, then just a few showers will remain to push across northeast Montana. Regarding the overall forecast, went with the RAP model for pops, which handled the developing line of precipitation pretty well. Minimal changes were made to the temperatures and winds with this update. Hickford Previous Discussion... Scattered showers and isolated thunderstorms have broken out yet again for the region and will continue to expand to cover many NE Montana locations through the rest of this afternoon and evening. Models continue to show spotty coverage, so I tried to show this the best that I could following the best model consensus coverage I could find, allowing for some blending due to general small uncertainties. By Monday most of the shower and thunderstorm activity will be confined to areas near and south of I-94 while skies clear nicely across our west. Monday night, our entire region clear out of precipitation, and the western states ridge of high pressure re-establishes itself. Expect hot temperatures and dry humidities to prevail Wednesday through Saturday. Fire weather concerns could easily be heightened and will need to be closely watched if the wind forecast increases. BMickelson && .AVIATION... FLIGHT CAT: Mainly VFR. DISCUSSION: Hit and miss showers and thunderstorms are possible through around 06Z tonight, then gradually clearing skies. WINDS: Generally light and variable overnight, then west to southwest at 5 to 10 kts on Monday. BMickelson / Hickford && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
852 PM PDT Sun Aug 5 2018 .SYNOPSIS... Smoke from California wildfires will reduce air quality across the region in the early part of the week. Above seasonal temperatures are likely to bring impacts from excessive heat through Wednesday. Otherwise dry conditions will prevail. && .UPDATE...Visible satellite loops prior to sunset showed smoke covering most of the forecast area from Clark County northward. The 00Z HRRR Smoke model initialized quite well and indicates the smoke will begin to lift to the northeast this evening, but additional smoke over central Nevada is then forecast to advect southward late tonight and Monday morning. The most dense smoke will be over Inyo/Esmeralda and central Nye counties through Monday. We should see a decrease in smoke concentrations over Clark County Monday. This trend is covered in the going WX grids and no immediate changes are needed. && .SHORT TERM...Tonight through Tuesday Night. A vast portion of the CWA is seeing the effects from smoke today. In most cases, the smoke is reducing visibility slightly, but affecting air quality as well. It still appears that the southern part of our area (San Bernardino County, southern Clark County) may see a small bit of relief later this afternoon as southwest flow kicks and and pushes the smoke back north and east. No such luck for the rest of the area. However, visibilities are expected to improve some as afternoon heating and low-level mixing occurs. The HRRR-Smoke model is still showing another push of high smoke concentrations down through Inyo County tonight. I added reduced visibility down to 1 mile in both the public forecast and BIH TAF given these concentrations. Conditions will be similar to what we saw yesterday and the day before in that area. Likewise, this same process would again spread lower concentrations of smoke over the rest of the area. Thus, we are in for another smoky morning on Monday. The other thing we will deal with is the upcoming excessive heat. Models have remained consistent in showing strong high pressure to build over the region leading to excessively hot temperatures that are forecast to last through mid week. Have gone ahead and upgraded the Excessive Heat Watch to a Warning for all areas staring Monday and continuing through Wednesday with Tuesday and Wednesday likely being the hottest days. .LONG TERM...Wednesday through Saturday. Hot weather will continue Wednesday with a large high pressure ridge situated over Central Nevada, however, heat should begin to moderate in the long range period. This will be especially true for our southern zones as increasing surface moisture moves into the region. The impetus for the increasing moisture will be a likely hurricane moving northward along the west coast of Mexico, inducing a modest gulf surge up the Colorado River Valley on Wednesday. This surge is likely to be fairly shallow, but will contribute to a few degrees of cooling south of I-15 starting Wednesday. A few isolated showers and storms may form during the afternoon and evening as well across the higher terrain of our southern zones. High pressure will remain dominant across much of the Interior West through the weekend, but increasing low grade monsoonal moisture will result in gradual cooling and modest increases in thunderstorm potential as we head into the late week timeframe, particularly along and south of I-15. Further north, delayed moisture arrival will mean prolonged warm temperatures through the end of the week. The Excessive Heat Warning extending through Wednesday looks good, though it may need to be extended into the Thursday-Friday period for areas north of I-15 where intense heat is likely to linger. && .AVIATION...For McCarran...Expect south to southwest winds to remain at or above 10 knots through the night. Variable winds generally less than 8 knots can be expected Monday with decreasing smoke concentration in the terminal area. For the rest of southern Nevada, northwest Arizona and southeast California...Smoke concentrations near the surface will continue through Monday across Inyo County and south central Nevada, but will also impact eastern San Bernardino County, southern Nevada, and northwest Arizona. It appears smoke will be dense enough to cause visibility restrictions primarily at the Bishop terminal area. Variable winds will generally remain below 15 knots across the region except near Barstow where gusty west winds to 25 knots can be expected through early Monday morning. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE/AVIATION...Adair SHORT TERM...Lericos LONG TERM....Outler For more forecast information...see us on our webpage: or follow us on Facebook and Twitter