Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/13/17


Area Forecast Discussion
National Weather Service Wakefield VA
936 PM EDT Sat Aug 12 2017 .SYNOPSIS... A cold front will slowly sag south through the local area this evening into early Sunday morning. The front will stall across North Carolina on Sunday, and will push back north Sunday night into Monday as a wave of low pressure moves along the boundary. Additional areas of low pressure will move along the front into Tuesday, with high pressure finally building north of the region by Wednesday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Latest analysis indicating a sfc cold front from ern PA SW to the central/southern Appalachians. A prefrontal sfc trough remains in vicinity of the Chesapeake Bay. Currently, much of the convection is ahead of the cold front and pushing toward the Lower MD Ern Shore as of 930 pm. The earlier convection has dissipated, and hence the Flash Flood Watch for NE NC/SE VA has been cancelled. The highest PoPs (~60%) late this evening will be for the MD Ern Shore (which could exacerbate flooding in and around Salisbury), with the last several runs of the HRRR suggesting some of the pre- frontal convection propagating into central VA through 06z (30-40% PoPs), with some re- development possible (~30%) near the VA/NC border toward sunrise. Otherwise, PoPs will be aob 20% overnight. Warm and humid with lows ranging from the u60s NW to the m70s SE VA- NE NC. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... The frontal boundary will linger just S of the local area or near the SE VA/NE NC border Sun afternoon thru Mon...maintaining chc to likely PoPs across srn VA-NE NC into Sun night w/ PoPs aob 15% central/N. Flow aloft turns back a bit to the SW later Sun night/mon, lifting the boundary back N. PoPs increase back to 40-60% for much of the CWA (still highest S) Mon into Mon evening as the boundary is pushed back N. Highs Sun and Mon 80-85F. Lows Sun night in the m-u60s N to 70-75F S. The front lingers over the S Tue, as tropical low pressure remains well offshore. PoPs Tue drop off across the N, but remain in the high chance range over the S/SE. Highs tue again mainly 80 to 85 F. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Frontal boundary will be laying acrs NC and off the coast for Tue night thru Wed, then gets pushed well S of the area for Wed night thru Thu, as sfc high pressure builds into the region then off the coast. Will have slgt to chc Pops over srn half of the area Tue night and Wed, then mainly dry conditions (10-14% Pops) for Wed night and Thu. At least slgt chc to chc Pops return for Thu night thru Sat, as a trough of low pressure and a cold front affect the region. Highs will range fm the mid 80s to near 90 thru the period, with lows ranging fm the mid 60s to lower 70s. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Current radar analysis shows widely scattered showers/thunderstorms across portions of the region, but the majority of the activity from earlier has dissipated. A cold front crosses the region late tonight through early Sunday morning bringing another chance of showers and thunderstorms. SBY will have the best chance of seeing rain/storms overnight with lower confidence at other sites. MVFR ceilings will linger across much of the region through early Sunday morning with the potential for IFR ceilings across southeastern portions of the area. Conditions improve from north to south across the region on Sunday with potentially sub-VFR conditions lingering across far southern portions of the region. Outlook: Unsettled conditions with periodic convection continues through Tuesday as a boundary stalls across the region, allowing for a series of disturbances to cross the area. && .MARINE... No headlines in the short term tonight thru Mon. A cold front will drop acrs the waters late tonight into Sun morning. Expect SSW winds 5-15 kt this evening/early tonight, will shift to the NW or N very late tonight into Sun morning behind the frontal boundary. That boundary will then remain just S of the area or near the SE VA/NE NC border fm later Sun thru at least Tue. Sfc high pressure will then push that boundary well to the S Wed into Thu. N winds 5 to 10 kt will become NE during Sun, then expect NE thru SE winds 5 to 10 kt Sun night thru Wed. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB NEAR TERM...AJZ/LKB SHORT TERM...ALB/LKB LONG TERM...TMG AVIATION...AJB/MPR MARINE...TMG
Area Forecast Discussion
National Weather Service Albany NY
845 PM EDT Sat Aug 12 2017 .SYNOPSIS... A cold front will sweep through the region tonight. A cooler and less humid air mass will return to the region tomorrow. The fair and dry weather will continue on Monday as high pressure builds in with seasonable temperatures. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... SEVERE THUNDERSTORM WATCH 447 IS CANCELLED AS OF 8PM. The severe thunderstorm watch has been cancelled. The near- severe line of thunderstorms stretches from southern Vermont back into Columbia County, NY. This line has not produced any severe weather in some time. It is not out of the question that a rogue severe report could still be possible. But in general, the threat for widespread severe has ended. HRRR suggests areas to west of ongoing convection have seen the last of precip for the night. SPC meso analysis still shows MUCAPE running around 500 j/kg. (ALY sounding was delayed due to thunderstorms in the area.). Will use the HRRR and current radar to time the convective line out of the CWA. Then maintain slight chance for TSRA/SHRA into the overnight hours. Some patchy fog is likely as well. The main front is located near Penn Yan NY. The front will clear the CWA overnight. Low-level cold advection occurs in the wake of the cold front with low temps in the mid 50s to lower 60s. The winds will increase out the west/northwest at 10 to 15 mph towards daybreak. It will feel less humid on Sunday. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... The period will be dominated by high pressure. First, an upper level trough will clear the region Sunday morning. There is a slight chance of showers through the morning. By afternoon, high pressure builds in and remains in control through Monday night. Another trough will approach the area on Monday night. With high pressure in place, skies should be mostly clear through the period. Temperatures will average near normal, with dew points below normal. && .LONG TERM /TUESDAY THROUGH SATURDAY/... The extended opens with a weak short-wave trough moving across the forecast area. This short-wave is associated with a broad upper level trough over southeastern Canada extending southeast into the Northeast. This feature should move through quickly with limited low- level moisture and instability to work with, so only a slight to low chance of showers was kept in the forecast. Temps look seasonable in the upper 70s to lower 80s in the valleys, and upper 60s to mid 70s over the higher terrain. Tuesday night through Wednesday night...the short-wave quickly moves east with the upper level trough sliding downstream with high pressure building in from the Great Lakes Region and east/southeast Ontario. Mid and upper level heights rise upstream for this period of dry weather, but another low pressure system will be moving into the upper Midwest/western Great Lakes Region by Wed. Overall, fair and dry weather is expected for the mid-week with lows in the 50s to lower 60s, and highs in the 70s to lower 80s with a few upper 60s over the high peaks of the southern Adirondacks, southern Greens, and eastern Catskills with comfortable humidity levels. Thursday...Clouds increase Thu ahead of a warm front to the low pressure system moving into the Great Lakes Region. There continues to be some timing issues with the medium range guidance and we went with a slight to low chance of showers and isolated thunderstorms especially Thu pm. Thu night into Saturday...The chances for showers and thunderstorms increase THU night into FRI with the warm front lifting north across portions of the region. A series of weak low pressure systems may move along the boundary with the zonal flow aloft. POPS were raised into the high chance category during the THU night to FRI time frame. The frontal boundary may still be near the region heading into the weekend with still a chance for showers and isolated thunderstorms. Temps look seasonable near this time frame. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... Still experiencing transmission difficulty with the KGFL observation. Thus AMD NOT SKED is added to the TAF. The only terminal with issues over the next hour or so is KPSF. Here a line of convection is just about on top of the airport. So, have included prevailing TSRA there. Elsewhere, the threat of thunder has ended at KALB and KGFL. For KPOU, high resolution models suggest the convective line will weaken before reaching the terminal. So have only included VCSH at KPOU. Looking for all terminals to drop to IFR in CIGS and VSBY overnight in BR. Once BR clears Sunday morning, VFR conditions will take hold for the remainder of the day. Outlook... Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. Slight Chance of SHRA. Tuesday: Low Operational Impact. Slight Chance of SHRA. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA. && .FIRE WEATHER... Showers and thunderstorms this afternoon and evening. Best coverage will be along and north of I-90. Drier weather works in for Sunday and Sunday night. Humidity levels will be at or above 90 percent tonight and Sunday night. Humidity on levels on Sunday will be as low as 50 percent. South winds tonight will yield to northwest winds on Sunday. Winds on Sunday will be northwest at 10 to 15 mph. && .HYDROLOGY... Showers and thunderstorms will bring rainfall to much of the HSA this afternoon and evening. Basin average rainfall will range from 0.25-0.50 inch across the northern third of the HSA to around 0.1 inch to the south. Any one thunderstorm is capable of producing 1-2 inches of rain. This could lead to some poor drainage flooding of low lying areas. . No river flooding is expected. High pressure builds in for much of the upcoming week bringing dry conditions. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .EQUIPMENT... The KENX radar will be down through early next week due to azimuthal motor and gearbox problems. Technicians will need to be brought in from the Radar Operations Center. In addition, KGFL ASOS continues to experience intermittent outages. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Wasula NEAR TERM...OKeefe/Wasula SHORT TERM...OKeefe LONG TERM...Wasula AVIATION...OKeefe FIRE WEATHER...BGM/OKeefe HYDROLOGY...BGM/OKeefe EQUIPMENT...Staff
Area Forecast Discussion
National Weather Service Bismarck ND
909 PM CDT Sat Aug 12 2017 .UPDATE... Issued at 858 PM CDT Sat Aug 12 2017 Now seeing the short wave circulation in the radar reflectivity and this should track southeast with time tonight. Updated the POPs and QPF with the latest HRRR model run and also averaged the QPF with the HRRR. Will see more rain across south central North Dakota tonight. The latest CAM models, especially the RAP, bring in fog over more of the south central. With the recent rains extended the areas of tonight further east, but did not go to the James river valley. UPDATE Issued at 710 PM CDT Sat Aug 12 2017 Focused on the south central for heavy rain with the thunderstorms this evening. generally increased POPs to likely across this area. UPDATE Issued at 446 PM CDT Sat Aug 12 2017 Quick update for the band of thunderstorms from Beach to Hazen to south of minot. This area of thunderstorms has been producing heavy rain. Do not expect flash flooding but getting some reports of standing water on roads, along I-94 near Medora for example. && .SHORT TERM...(This evening through Sunday) Issued at 248 PM CDT Sat Aug 12 2017 Latest GOES16 water vapor imagery loop shows a mid level upper low circulating over northwestern ND, soon to transition south as a stronger shortwave rotates and into southwest/south central ND this evening. The mid/upper low slowly meanders into the southern James River Valley after midnight. Areas of fog 05z-15z Sunday for southwest and south central ND has been added to the gridded forecast per HRRR/RAP13 Surface Visibility Forecast. For this afternoon and evening, per water vapor imagery, our attention is directed toward a pair of 700mb-500mb shortwaves noted over Dawson and Custer Counties in eastern Montana. The GFS/RAP13 have both initialized this very well with the current location, and begins pushing these shortwaves into southwestern ND 21z-00z, then into far south central 03z-06z, and exiting the southern James River Valley 12z-15z Sunday. Large scale ascent increases this afternoon southwest and far south central in response to the shortwave aloft and the left exit region of a 60kt 300mb jet streak scooting through southeastern MT/southwestern ND. A cold pocket of -16C also aiding in destabilization. Air parcels will encounter moderate instability with mixed layer CAPE between 1000-2000 J/kg, Effective Bulk Shear values of 40kt, and mid level lapse rates around 7.5C/km. With that said, will continue with previous forecasts and maintain a mention of severe thunderstorms in far southwest and into far south central ND through early this evening. This is also in line with the Marginal Severe Thunderstorm Risk per SPC. Main threats of large hail and damaging winds continue. Localized heavy rainfall (1 to 2 inches) per WPC in a short amount of time with any thunderstorm remains valid as well. The Simulated High Resolution Composite Reflectivities in decent agreement with developing pockets of showers/thunderstorms from Williston south to Bowman, which is in line with the current Regional Radar. The Non-Supercell Composite Index is between 1 and 2 over northwest ND. Will need to monitor the low level lapse rates and surface vorticity for any potential landspouts that could develop within this area. Scattered showers and thunderstorms continue through the evening, then shift away from southwest ND towards midnight. As mentioned above, concur with fog southwest and south central given the moisture, and crossover temperatures being met later tonight per BUFKIT soundings. .LONG TERM...(Sunday night through Saturday) Issued at 248 PM CDT Sat Aug 12 2017 A mid level transitory shortwave ridge shifts into eastern MT and western ND Sunday, behind the departing upper low. Increasing sunshine west Sunday morning, with clouds decreasing in the afternoon in the central. Lingering precipitation over the James River Valley Sunday morning, diminishes through 18z Sunday before ending. Highs in the 70s. The next in a series of shortwaves moves into eastern MT and western ND Monday with a chance for showers and thunderstorms. Additional shortwaves traverse through a southwest flow aloft Monday night through Tuesday night affecting western and central ND with showers and thunderstorms. A break on Wednesday with another shortwave slated for Thursday/Thursday night. Highs in the upper 70s to lower 80s Monday through Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 710 PM CDT Sat Aug 12 2017 Main hazards to aviation include widespread thunderstorms along and south of I-94 Saturday evening. After the Thunderstorms diminish Saturday night abundant low level moisture will support MVFR-IFR conditions in low ceilings and fog KDIK-KBIS-KJMS 09-15Z. Otherwise VFR. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...KS LONG TERM...KS AVIATION...TWH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
756 PM MDT Sat Aug 12 2017 .UPDATE... Issued at 747 PM MDT Sat Aug 12 2017 Strong storms moving out of our area so the Severe Thunderstorm Watch has been cancelled. Upstream showers/storms will mostly die as they move in. Some potential for some light showers from the convective remnants moving across from western Colorado. This will also keep a fair amount of cloud cover around much of the night, so the prospect for low clouds and fog late tonight is still questionable. && .SHORT TERM...(This evening through Sunday) Issued at 242 PM MDT Sat Aug 12 2017 Scattered thunderstorms over Weld County spurred on by a passing short wave to the north. Activity will continue to spread east southeast across the northeast plains where CAPES are around 2500 j/kg at this time. Large hail and damaging winds the main threat along with locally heavy rainfall. Scattered thunderstorms with brief heavy rain and small hail moving across northern Jefferson County. HRRR keeps the thunderstorms active through this evening with diminishing activity after midnight. Severe Thunderstorm Watch 449 in effect until 2300 mdt for Morgan, Logan, Washington, Logan, Sedgwick and Phillips counties. On Sunday the ridge will be a little stronger, but the flow aloft will remain northwesterly aloft. Shear not as strong, but sufficient CAPE over the northeast plains to support marginal risk for storms. Forecast soundings yield CAPES from 1300-2300 j/kg east of the urban corridor, highest over the northeast corner. Some patchy fog possible overnight for the plains may make its way into the Denver area by 12z. .LONG TERM...(Sunday night through Saturday) Issued at 242 PM MDT Sat Aug 12 2017 The zonal flow pattern is expected to continue for a few more days, with enough moisture lingering over the state to produce afternoon and evening thunderstorms. The continuing moderate westerly flow aloft will keep storms moving along. Models do not pin point any particular day with heavier rain, so it is difficult to say any day will have flooding problems. After Wednesday, the GFS and ECMWF show stronger upper level ridging building over the western U.S. which will start to dry things out across Colorado. This will result in Thursday and Friday being the driest days of the week. Temperatures will remain around seasonal normals through the forecast period. Locally heavy rain will be the primary threat from each afternoon of shower activity. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 747 PM MDT Sat Aug 12 2017 VFR conditions are expected to prevail through Sunday. There is a chance that there will be areas of fog with localized IFR conditions between 10z and 15z. Slight chance of a thunderstorm Sunday after 21z with variable winds gusting to 30 knots. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Gimmestad SHORT TERM...Cooper LONG TERM...Dankers AVIATION...Gimmestad
Area Forecast Discussion
National Weather Service Taunton MA
1109 PM EDT Sat Aug 12 2017 .SYNOPSIS... Unsettled weather this evening as a cold front moves through tonight. High pressure brings dry weather Sunday and Monday. A cold front swings through the region Tuesday night. Low pressure passes just offshore on Friday and early Saturday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Only minor tweaks to the forecast this evening. Monitoring flooding risk across portions of northwest MA. Still expecting a cold front to move across our region overnight. 7 PM update... Southwest flow aloft continues. Cold front over Central NY and PA moves east. Radar shows tstms across Eastern NY and Southern VT moving northeast. One storm south of Albany is trending toward the NW corner of Mass and may cross part of western Franklin County between 730 pm and 8 pm. HRRR forecast is a little slower, but does show potential for tstms in NW Mass between 8 and 9 pm. The HRRR brings the line to Orange and Springfield around 11 pm, but shows a weakening trend by that time. The showers quickly fade out shortly after that. We have made a few small adjustments to the pops but remain close to the previous forecast. Main concern will be one or two heavy downpours, as PW values are around 1.5 inches. No change in the outlook for low clouds and fog, or for temperatures. Previous discussion... Cold front will push through the region tonight. Lingering showers and possible storms may push through into the interior but the overall coverage of any precip will be limited. A few spot showers are also possible across the Islands overnight in a difluent region, but confidence is a bit lower. Therefor continued to mention a chance for showers for that region overnight. Aside from precip chances, the biggest issue will be fog and stratus. If today was an indicator anticipate widespread stratus and fog across the region tonight. Higher dewpoints continue to advect into the region ahead of approaching cold front resulting in a low temp/dewpoint spread. Highest confidence in low vsbys is across the eastern half of the region. However held off on dense fog advisory as gusty winds overnight may keep vsbys from remaining below 1/4 of a mile. Regardless, it will be slow going overnight for any travelers. Once the front passes through from west to east, winds will switch to a more westerly direction. This will bring in dry air and lift the fog quite quickly. Best chance for this is across the CT valley and into central MA before sunrise. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Sunday and Sunday night...High confidence. Cold front will be offshore by Sunday morning. Southwest flow aloft will turn more to the northwest as upper level trough axis moves through. This will allow for some weak CAA during the day, but moreso dry air will push into the region. Despite the CAA aloft, temps will be warmer than today with temps in the low to mid 80s. Steepening lapse rates with some low level moisture will aid in the development of diurnal cu during the day. Otherwise dry weather will prevail with breezy west winds around 15 to 20 MPH. Clearing skies and light winds will remain over the region Sunday night thanks to building high pressure. Radiational cooling will occur resulting in temps to fall into the mid to upper 50s. Metro regions of PVD and BOS will remain slightly warmer, closer to the mid 60s. Some patchy fog may develop in the typical low lying regions, but will not be widespread. && .LONG TERM /MONDAY THROUGH SATURDAY/... Big Picture... A pair of shortwaves will move across the northern tier of the USA this period. One shortwave, currently over the Northern Plains, crosses New England later Tuesday. The second shortwave, currently offshore of British Columbia, arrives here at the end of the week. Model mass and thermal fields are similar through early Wednesday, then diverge. Thus, higher than average confidence Monday and Tuesday followed by diminishing confidence mid to late week. Details... Monday...High confidence. High pressure moves overhead. With light flow, this will allow sea breezes to develop along the coast. Temperatures at 850 mb will be around +16C, which would support max sfc temps in the mid 80s. Fair skies and light winds should allow areas of fog to develop Monday night, especially across the CT River Valley. Dew points of 55-65 should allow a similar range of min temps Monday night. Tuesday...Moderate confidence. A shortwave crosses New England during the day. Models show a surface trough crossing the region at this time, but thickness fields show little change in airmass, so this is probably not an actual cold front. Moisture fields show precipitable water values around 1.25 inches, not exceptional for August. Cross-sections show the moisture is limited in extent, mostly below 700 mb. Stability parameters are fine, with totals in the upper 40s and lifted index sub-zero. Models also show a theta-e ridge moving along with the trough. With these mixed signals, we will indicate low-end chance pops for the afternoon/evening. Otherwise a fine day with 850 mb temps 15-16C supporting sfc high temps in the mid 80s. Wednesday...Moderate confidence. Northwest flow aloft will push a cold front through the region. Airmass will be dry, so no showers expected. More likely a wind shift out of the north or northeast. Temps aloft still support max sfc temps in the 80s. Thursday...Moderate confidence... Fair weather during the day as high pressure departs to the east. A warm front approaches from the west, and this should bring increasing mid and high clouds. Still plenty of dry air near the ground, so no precip expected during the daytime hours. Thursday night through Saturday...Low-moderate confidence. Clouds lower and thicken Thursday night with a deep column of moisture over New England. The deep column lingers through Friday. Low pressure at the surface moves along the approaching warm front. The 12Z suite of models is showing this low moving along or just south of the New England coast, keeping our area in a moist east flow. Expect clouds and rain/showers Thursday night and Friday. Friday-Saturday...Low pressure moves across from the Great Lakes. GFS redevelops the low south of New England Friday, then moves it east of the region Saturday. This would keep us in an easterly flow, bringing clouds and rain. Potential for leftover showers on Saturday...an onshore flow lingers in Eastern Mass with lingering moisture below 700 mb, but drying air above that level. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/... Tonight...Moderate confidence. Mixed VFR/MVFR to start, dropping to IFR. LIFR is possible across the eastern MA and RI terminals. A shower/tstm is possible from 00Z to 06Z mainly in NW Mass. Conditions will improve from west to east after 06z as winds shift from the south to a more WNW direction. Sunday...High confidence. VFR. Breezy W winds near 15-20 kts. Sunday night...High confidence. Mainly VFR. Patchy MVFR fog possible in low lying terminals. KBOS Terminal...High confidence in trends. KBDL Terminal...High confidence in trends. Spot shower/storm is possible after 01z. Outlook /Monday through Thursday/...Moderate confidence. VFR most of the period. Areas of IFR cigs/vsbys in early morning fog Monday and Wednesday. Afternoon sea breeze Monday along the coast. Brief MVFR cigs/vsbys in showers and t-storms Tuesday afternoon/evening. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/...High confidence. Southerly flow will continue tonight allowing for winds to strengthen just a bit ahead of approaching cold front. A few gusts near 20 kts is possible. This will help increase seas to above 5 feet tonight and into tomorrow especially across the southern waters. High pressure building late in the day on Sunday and especially Sunday night will help relax seas below SCA. Aside from wind and seas, vsbys will once again be an issue for tonight. Anticipate widespread fog with vsbys below 1SM. Conditions will lift by Sunday morning as cold front moves well offshore. Outlook /Monday through Thursday/...Moderate confidence Winds and seas will remain below Small Craft Advisory levels through the period. Low pressure passing well offshore may spread light rain into the southern waters Monday and Tuesday. There may be some vsby restrictions in showers Tuesday, and in fog on Monday and Tuesday nights. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 2 AM EDT Monday for ANZ254-255. Small Craft Advisory from 5 AM to 8 PM EDT Sunday for ANZ235- 237. Small Craft Advisory until 11 PM EDT Sunday for ANZ256. && $$ SYNOPSIS...WTB/Dunten NEAR TERM...WTB/Belk/Dunten SHORT TERM...Dunten LONG TERM...WTB AVIATION...WTB/Dunten MARINE...WTB/Dunten
Area Forecast Discussion
National Weather Service Caribou ME
924 PM EDT Sat Aug 12 2017 .SYNOPSIS... A weak frontal boundary will bring some showers and thunderstorms across the area tonight with some fog. A cold front will cross the region Sunday with another round of showers and thunderstorms, followed by high pressure on Monday. && .NEAR TERM /THROUGH SUNDAY/... 9:24 PM update...Watching an area of thunderstorms on radar coming out of the western mountains. The activity has been bowing out and will need to be watched, but it likely will weaken as it moves toward southern Piscataquis County. Some of this activity will likely work across central potions of the CWA very late this evening. There is another storm that is quite strong that we are watching in Quebec to the west of Aroostook County that will also likely weaken before it reaches the CWA, but bears close watching. There may not be much additional shower or thunderstorm activity behind this until the cold front comes through Sunday afternoon. Made some adjustments mainly to the PoPs based on the latest radar and near term model trends. Also added in some gusty wind until midnight across the western zones as any of the stronger convection could produce some wind. Previous discussion... Scattered thunderstorms overnight with another round expected for Sunday. Showers and tstms setting up over w and nw areas as s/wv lifts up across the region from the NYS region. Some lighter showers were seen on radar lifting up across the region from the s. The latest SPC meso analysis showed best CAPE and lapse rates residing across the w and nw into early evening. Some of the stronger storms across the wnw could contain strong wind gusts and hail. First batch of activity is shown by the latest HRRR and RAP to diminish after 8 pm. Some fog is expected to set up later in the evening into the overnight hrs. Decision was to hit the downeast and western areas hardest w/the fog and went patchy fog elsewhere. A second round of activity is slated to develop across the region overnight into early Sunday morning as the cold front apchs from Canada. There appears to be a pre-frontal boundary that moves across the region which could allow for some convection to fire back up well after midnight into the daybreak hrs. The RAP and GFS show elevated instability as far e as BGR and BHB into Sunday morning. The NAM is weaker as is the HRRR. There does look to be elevated CAPE of 600-800 joules w/0-6km shear apchg 30 kts. So, if storms do fire, some could have some gusty winds. Decided to carry tstms into the Downeast, but w/stable layer in place, confidence is low to have enhanced wording. The evening crew can assess this further. For Sunday, SPC has placed the entire region in a Marginal Risk for a few tstms to become severe. This will be a challenge as there could some action in the morning w/the pre-frontal boundary and then the short range guidance shows a second round across northern areas by late morning into the early afternoon. Instability parameters such CAPE(700-1000 joules) and 0-6KM shear of 30 kts favor organized potential. Lapse rates do look as though they steepen by later morning especially in the mid levels to allow for updrafts. Given this, added the mention of strong wind gusts and hail to the forecast. Stayed close to the midnight crew`s assessment of 70s w/the warmest temps across the central and downeast areas. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Expect clearing skies Sunday night behind the departing cold front and mainly sunny skies on Monday. Lows Sunday night will range from the upper 40s to lower 50s. Highs on Monday will range from the mid to upper 70s north and upper 70s to near 80 central and down east. Expect fair weather Monday night in advance of an approaching cold front. Lows Monday night will range from the mid to upper 50s across the region. Tuesday will see a chance for showers and thunderstorms as a cold front begins to cross the region. Highs on Tuesday are expected to range from the mid 70s to near 80, except cooler along the coast. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A few showers may linger into Tuesday evening, followed by partial clearing Tuesday night. A secondary front/trof will cross the region on Wednesday. This feature combined with a pool of cold air aloft, will once again result in the chance for showers, mainly during the afternoon. Thursday and Friday are looking like a mainly dry days, as latest model runs are suggesting the late week system may stay off to our south, as confluent flow aloft allows for more in the way of high pressure to build build in from the north. The dry weather may hold into the beginning of next weekend if the system remains to our south. Daytime high temperatures through the long term are expected to be at, or even a bit below normal for this time of year. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... NEAR TERM: VFR and MVFR this evening. It does look like all terminals will be seeing conditions drop to IFR w/the potential for LIFR from HUL down to KBGR and KBHB. Fog will be a nuisance overnight w/the threat for a tstm. IFR/LIFR Sunday morning gradually improving to MVFR by later morning w/another round of tstms. Looking for conditions to go to VFR by later Sunday afternoon into evening. SHORT TERM: Generally VFR through the period, except in any afternoon scattered showers and thunderstorms Tuesday and Wednesday, which may result in briefly lower conditions. Could also see the potential of lower clouds and stratus making their way into the vicinity of the Bar Harbor airport later Monday night into Tuesday morning with local IFR conditions possible. && .MARINE... NEAR TERM: No headlines. The biggest issues will be the fog tonight into early Sunday which could hamper navigation. Tstms are a threat as well. SSW winds are expected to increase ahead of the cold front on Sunday to 10-15 kts. This will allow seas to build some but they will remain below 5 ft. Decided to add some gusts to 20 kts for the outer zones. SHORT TERM: Winds/seas are generally expected to remain below small craft advisory levels through the period. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/Hewitt Short Term...Duda Long Term...Duda Aviation...CB/Hewitt/Duda Marine...CB/Hewitt/Duda
Area Forecast Discussion
National Weather Service Dodge City KS
613 PM CDT Sat Aug 12 2017 ...UPDATE TO AVIATION... .SHORT TERM...(This evening through Sunday) Issued at 302 PM CDT Sat Aug 12 2017 Scattered weak showers persisted this morning and continues into the afternoon, despite relative weak mid level lapse rates. More impressive low level lapse rates farther west may be the narrow zone where a few non severe thunderstorms develop this afternoon, aided by weak vorticy advection rotating through the panhandles and western Oklahoma. As any forcing becomes quickly removed from the area this evening precipitation chances should dwindle with time. Some convective allowing models develop one or more mcs clusters from ne Colorado into northwest Kansas during the overnight. In most cases the models suggest the convection decays as it reaches the west central Kansas counties. As such pops will be ramped up modestly overnight, as well as an introduction of fog across the southwest where widespread low stratus should quickly redevelop. HRRR is the most aggressive model with respect to thunderstorms early Sunday in the far western counties and may be overdone when considering the other CAMS. Additional development Sunday would be contingent on how fast the stratus might be mixed out if at all. The NAM develops no convective precipitation at this time. .LONG TERM...(Sunday night through Saturday) Issued at 302 PM CDT Sat Aug 12 2017 A relatively cool period continues through the extend, although temperatures begin to revert back toward normal climatological highs by mid week and beyond. Probability for precipitation should remain low though mid week in the absence of any significant lift/forcing. However by wednesday the models begin to carve out a western/Intermountain upper trough which should lend itself to eject shortwave energy into the Central Plains region. Western Kansas will have precipitable water values within the 90% moving average, conducive for MCS maintenance any given period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 612 PM CDT Sat Aug 12 2017 Low level stratus will prevail/redevelop across much of southwest Kansas tonight resulting in MVFR cigs in the vicinity of KGCK, KLBL, and KDDC. KHYS could see MVFR cigs toward daybreak Sunday morning while the remaining TAF sites could possibly see IFR cigs. High relative humidity and very light southeast winds could result in areas of fog development late tonight with MVFR vsbys possible. Light southeast winds will persist through early Sunday as surface high pressure remains locked in across the Upper Midwest. && .PRELIMINARY POINT TEMPS/POPS... DDC 63 82 66 87 / 20 20 20 20 GCK 63 81 65 88 / 20 20 30 20 EHA 63 82 63 87 / 20 20 30 20 LBL 63 81 66 88 / 20 20 30 20 HYS 62 82 66 88 / 10 10 10 10 P28 64 83 68 87 / 30 20 20 30 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
655 PM CDT Sat Aug 12 2017 .AVIATION... Mostly clear skies through the evening. May start to see a little more cirrus come in from the west as convection continues west and northwest of the Hill Country. Main question overnight will be if MVFR ceilings develop once again Sunday morning. MOS guidance does not paint a very robust picture of having widespread morning cloudcover. Latest RAP and HRRR runs show a swath of drier air moving in from the south overnight which may in fact hamper any low cloud production. Want to see more run to run consistency in the models before the inherited MVFR ceilings are removed for AUS/SAT/SSF. So in the meantime I have taken the prevailing MVFR for Sunday morning and have dropped it to a TEMPO group to show a downward trend in probabilities and confidence. The 00Z model runs hopefully will show a continued trend. Sunday mid morning through afternoon should be VFR with high pressure dominating. Wind from the south should remain below 15kt. && .PREV DISCUSSION... /ISSUED 200 PM CDT Sat Aug 12 2017/ SHORT TERM (Tonight through Sunday Night)... The mid and upper level ridge will remain in place across south central Texas through Sunday night. Look for continued hot and dry weather, with hazardous afternoon heat index values across the coastal plains east of Interstate 35. Will let the overnight shift refine the hottest area and issue a heat advisory for Sunday. LONG TERM (Monday through Saturday)... No major change in forecast model trends, we still expect a weakening of the upper level ridge by mid-week, with a trough moving through the central Great Plains as a source of lift late Tuesday for Val Verde County, and on Wednesday for the rest of the area. Even with the tail end of the trough, overall moist air content and instability will be low enough for only 20 percent PoPs. A new ridge develops over Texas at the end of the week into early the next week. While this ridge will suppress cloudcover and make for great solar eclipse viewing on Monday, August 21st, it also means most locations will remain dry, so continue watering plans in accordance with local restrictions. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 77 101 77 100 77 / 0 0 0 0 0 Austin Bergstrom Intl Airport 76 100 76 99 76 / 0 0 0 - 0 New Braunfels Muni Airport 76 100 75 101 76 / 0 0 0 0 0 Burnet Muni Airport 75 98 74 97 74 / 0 0 0 0 0 Del Rio Intl Airport 78 104 78 102 79 / 0 0 0 0 0 Georgetown Muni Airport 77 99 76 98 76 / 0 0 0 0 0 Hondo Muni Airport 75 102 75 102 75 / 0 0 0 0 0 San Marcos Muni Airport 76 100 76 99 76 / 0 0 0 0 0 La Grange - Fayette Regional 77 100 77 99 77 / 0 0 0 10 0 San Antonio Intl Airport 77 100 77 101 77 / 0 0 0 0 0 Stinson Muni Airport 76 100 76 100 77 / 0 0 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 7 PM CDT this evening for the following counties: Atascosa...Bastrop...Caldwell...De Witt...Fayette... Gonzales...Guadalupe...Karnes...Lavaca...Lee...Wilson. && $$ Mesoscale/Aviation...09 Synoptic/Grids...Allen Public Service/Data Collection...Treadway
Area Forecast Discussion
National Weather Service Grand Forks ND
950 PM CDT Sat Aug 12 2017 .UPDATE... Issued at 948 PM CDT Sat Aug 12 2017 Based on current radar trends and guidance from the HRRR have trimmed back on pops across the north through midnight. Still unsure of coverage across the north as upper low drops through so maintain low pops later tonight. The far s-se will see a break until the next band moves in aft midnight. UPDATE Issued at 654 PM CDT Sat Aug 12 2017 Trimmed pops over the DVL basin where returns are having a tough time staying organized. Otherwise forecast on track at this point. && .SHORT TERM...(This evening through Sunday) Issued at 250 PM CDT Sat Aug 12 2017 Main challenge for the short term will be heavy rain potential across the south. In general models continue to push south the heaviest precip into northeastern SD and southwestern MN...although Grant County up into Otter Tail county still seeing potential for one to one and a quarter inch of rain fall. Elsewhere looking at one half to an inch of rain along and south of the I-94 and Highway 10 corridor. Upper low over w cntrl ND will drop into the southern valley by 12Z Sun as an inverted trough associated with sfc low pressure over far s cntrl SD extends NE into sw/w central MN. A 35 to 45 kt low level jet will push north into the Watertown SD/Madison MN area...with the heaviest precip amounts per 12Z NAM being along a Watertown SD to Morris MN axis on the nose of the llj. This heavier precip band is further south than prev forecast hence slightly lower amounts across southern zones. Showalters increase to positive roughly north of Fargo and generally keeping showery activity with isold thunder for p-type overnight. Main precip ban on Sunday then moves into the Alexandria area during the morning and on into Brainerd in the aftn...with the NW edge clipping my far sern zones where storm total QPF values exceed an inch due to the longer duration of precip over this area. Overnight lows tonight in the mid 50s and the coolest Sunday highs over the southeast, where rain and isold thunder will limit daytime highs to the mid 60s. Areas across the north will reach the upper 70s with more solar available. .LONG TERM...(Sunday night through Saturday) Issued at 250 PM CDT Sat Aug 12 2017 (Sun night - Tue) Short wave will exit the area by Monday, followed by a weak bubble of high pressure that will prevail during the daylight hours. The next system will begin to affect the western FA by late Monday night. Timing differences exist between the GFS and the ECMWF with the latter being much quicker initiating convection during the morning on Tue. Given that the GFS is usually the faster model and this time is more laggard, believe that we`ll favor it with a slower solution this time. (Wed-Sat) CAPE values will be modest overnight Tue into Wed (still favoring the souther forecast area) but stronger low level forcing in the vicinity of frontal boundary should yield areas of shwrs/tstms with particular focus farther south. The GFS slowly moves the main upper trough through the area Wednesday and Wednesday night, bringing more precipitation to MN during this time. The next precipitation opportunity will present itself on Fri as a healthy wave traverses the Northern Plains. Temperatures throughout the upcoming week should stick very close to mid August averages. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 654 PM CDT Sat Aug 12 2017 Best shower potential will be over the FAR site where tempo/vcsh groups added. Elsewhere potential looks limited at this point as rain having a tough time holding together much north of I94. General VFR cigs/vsby through most of the period. Some indications of mvfr cigs over the west and south tomorrow morning. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Voelker SHORT TERM...Speicher LONG TERM...WJB AVIATION...Voelker
Area Forecast Discussion
National Weather Service Flagstaff AZ
327 PM MST Sat Aug 12 2017 .SYNOPSIS...Expect typical monsoon weather conditions through the weekend. Drier air will bring a decreasing trend in storms beginning Monday, with isolated storms from Tuesday onward. && .DISCUSSION...Active afternoon across northern Arizona with scattered storms and isolated very heavy rain. Small hail was also reported. HRRR does show storms continuing through the night moving from west to east across Coconino County into central Navajo and Apache Counties. Low level moisture remains plentiful across northern Arizona through Sunday. The steering flow will push storms toward the E-NE. Fairly slow storm motion will bring a chance of localized heavy rainfall/flooding. Hail and gusty winds will also accompany the stronger cells. On Monday, a trough of low pressure will move out of the Pacific Northwest into the Great Basin. This will push monsoon moisture east of Arizona and will bring drier are over the state. Storm chances will drop to the slight chance category for most areas. By Tuesday, further drying is expected as the trough moves across Arizona. Breezy to windy southwest winds will also develop on Monday and Tuesday. Near average daytime temperatures should persist through at least Friday. && .AVIATION...For the 00Z package...Scattered showers and thunderstorms will continue through the afternoon and evening across northern AZ, with localized MVFR/IFR conditions in the strongest storms. Storm coverage and intensity will decrease after 03Z, with redevelopment expected during the daylight hours Sunday. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Daily rounds of showers and thunderstorms will continue through Monday, with temperatures slightly below normal. Tuesday through Thursday...A drier air mass will move back into the region with significantly decreased storm chances. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...MAS AVIATION...KD FIRE WEATHER...KD For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
952 PM MDT Sat Aug 12 2017 .SHORT TERM...(Tonight through Sunday night) Issued at 334 PM MDT Sat Aug 12 2017 Some light showers lingered across the north this morning with plenty of sun to work on the moisture in place to fire storms over all higher terrain this afternoon. Seems a bit more active this afternoon than yesterday, with convection blossoming across eastern Nevada, Utah and northern Arizona. This convection to the west is associated with a shortwave that will be tracking through the region this evening and overnight. Pretty much all the near term models are indicating some form of storm activity continuing through the overnight hours tonight with the HRRR picking up on this activity fairly well. Storms are expected to increase across eastern Utah late this afternoon and move into western Colorado this evening with the east-central Utah and west-central Colorado corridor being favored for overnight convection through the early morning hours on Sunday. Increased PoPs as a result as confidence is a bit higher due to model consistency picking up on this shortwave with the NAMNest picking up on this activity in yesterday`s model runs. This shortwave disturbance and storm activity also comes with an increase in precipitable water (PW) values above an inch for most areas with pockets of 1.25 near the Four Corners. Expect some lingering isolated to scattered showers after sunrise Sunday over the eastern zones as this shortwave progresses eastward. Overnight lows were much cooler the last couple nights than model guidance suggested, due to the rain- cooled air from evening and overnight shower activity. Lowered low temperatures tonight as a result. Convection is expected to re-fire across the higher terrain Sunday afternoon as sufficient moisture and enough instability remains in place with storm activity drifting into valleys late afternoon and evening as another shortwave tracks across. Expect a similar day on Sunday like today (Saturday). Storms both days will be capable of heavy rainfall, frequent lightning, gusty outflow winds of 40 to 50 mph and some small hail as decent shear exists for some sustainable updrafts. Most storm activity should wind down after midnight Sunday night as no distinguishable shortwave moves through. Cannot completely rule out overnight convection though so kept some isolated mention in the forecast for some areas. .LONG TERM...(Monday through Saturday) Issued at 334 PM MDT Sat Aug 12 2017 Southwest flow will increase Monday as an upper level trough deepens over the western states into the Desert Southwest. Good upper level support exists with the upper level jet to the west over Utah, so expect a fairly active day on Monday with storm development. One concern is that some drier air tries to work into the Four Corners region with this trough. However, plenty of moisture will remain for storms to fire and become widespread with strongest storms to fire along the moisture gradient. This slightly drier air may help to increase instability in the atmosphere for stronger storms. Activity looks to increase Monday evening as a leading shortwave moves through the flow for convection to continue overnight into Tuesday morning. The upper level trough and associated cold front moves through on Tuesday, allowing for a fairly active day. Due to the low dew point depressions, remnant moisture and forcing in place, raised chances and coverage of storms Monday through Tuesday. Expecting these to be the most active days. Cooler air moves in behind this trough with drier air as well. The pattern overall looks to favor a drying trend from mid-week through the end of the week for a downturn in storm activity. Thinking that enough moisture will still hang around for daily afternoon convection over the higher terrain with most lower elevations drying out and slowly warming up towards the end of the week from near normal/slightly below normal values towards slightly above normal. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 952 PM MDT Sat Aug 12 2017 Scattered showers and thunderstorms will continue across eastern Utah and western Colorado through 10Z tonight and come to an end shortly after sunrise Sunday. Another round of storms will develop after 16Z Sunday and persist well into the evening hours as a disturbance treks through the region. As has been the trend the past couple of days, heavy rain, gusty and erratic winds to 45 kts, small hail and frequent lightning will accompany the strongest storms. Expect ILS breakpoints to be met in the vicinity of showers with mountains tops occasionally obscured. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MDA LONG TERM...MDA AVIATION...TGJT
Area Forecast Discussion
National Weather Service Green Bay WI
1042 PM CDT Sat Aug 12 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Sunday Issued at 224 PM CDT Sat Aug 12 2017 The latest RAP analysis and satellite/radar imagery show high pressure centered over the northern Mississippi Valley early this afternoon. Skies are mostly clear to partly cloudy across the region, with only high based cu present. Looking upstream, shortwave troughing is slowly moving east over the northern Plains, with scattered showers and storms over the Dakotas. As this shortwave moves east, clouds and temps are the main forecast concerns. Tonight and Sunday...Once the high based cu dissipates, high pressure will provide mostly clear and quiet conditions for much of the night. Will start to see cirrus move into north-central WI late tonight ahead of the shortwave. But the cirrus should not hold up temps much, so will continue to side with the colder guidance for lows. Min temps should range from the lower to mid 40s in the cold spots to mid 50s near the Lake. Mid and high clouds will continue to increase across the region through the day as the shortwave energy arrives from the west. It will run into a much drier airmass below 600-700mb, as deeper moisture will remain west of the region. But combined with some high based cu once again, should see skies turn partly sunny to mostly cloudy after a relatively sunny start. Temps will be near todays readings, perhaps a degree warmer. .LONG TERM...Sunday Night Through Saturday Issued at 224 PM CDT Sat Aug 12 2017 Return flow behind departing surface high will bring increased low- level moisture to area late Sunday and Monday. Weakening shortwave trof will move across the state Monday with attendant shower/storm chances. Energetic jetstream over north Pacific undercuts block over central Canada with another shortwave trof moving into Upper Midwest late Tuesday-Wednesday. Models in general agreement on this scenario, although GFS is a bit more aggressive with convection. Yet another shortwave trof moves in later in the week as Pacific energy continues to generate fast-moving systems. GFS again a bit stronger with late-week system. Temperatures should generally be near or above normal during the upcoming work week. && .AVIATION...for 06Z TAF Issuance Issued at 1042 PM CDT Sat Aug 12 2017 Mostly clear skies expected tonight, with ground fog possible for a few hours around sunrise. VFR conditions forecast Sunday with middle and high clouds arriving from the west. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......JKL AVIATION.......RDM
Area Forecast Discussion
National Weather Service Northern Indiana
647 PM EDT Sat Aug 12 2017 .SYNOPSIS... Issued at 219 PM EDT Sat Aug 12 2017 High pressure will build into the Great Lakes tonight and linger through early next week providing fair weather. Temperatures will be cooler than normal over the weekend, with a slow warming trend early next week. The high will move to our east by the middle of next week allowing moist southerly flow to return. A low pressure system moving east from the plains will interact with this moisture providing a good chance for showers and thunderstorms around Wednesday night or Thursday. && .SHORT TERM...(This Evening through Sunday) Issued at 219 PM EDT Sat Aug 12 2017 Shortwave dropping south through the flow stirring up some showers across eastern portions of Michigan. HRRR suggests as this drops into mainly NE areas some isolated showers could form. Given trends updated earlier for token 20 pop for a few hours before rapid decrease in pops. Clearing skies and diminishing winds may set the stage for some patchy fog overnight, but boundary layer moisture may be low enough to keep fog from developing. Will punt to eve shift to monitor trends. No sensible weather concerns Sunday with little more than fair weather cu mainly SE during peak heating. Below normal temperatures will persist with highs in the middle to upper 70s. && .LONG TERM...(Sunday Night through Saturday) Issued at 219 PM EDT Sat Aug 12 2017 Dry weather to persist through at least Tuesday night with models still varying on exact timing of series of waves starting as early as Weds afternoon into Friday. Highest pops still appear to be in the Wed ngt/Thurs window, but somewhat skeptical if likely pops will work out. Have maintained general consensus for now. Temperatures will head back towards more normal or somewhat above normal levels with increasing humidity towards the second half of the week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 645 PM EDT Sat Aug 12 2017 Boundary layer moisture combined with light winds will favor patchy ground fog to form over the southern two thirds of the forecast area around 10Z-14Z. This will mainly affect the FWA TAF. Otherwise VFR conditions prevail. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Beach Hazards Statement until 10 PM CDT this evening for INZ003. MI...Beach Hazards Statement until 11 PM EDT this evening for MIZ077. OH...NONE. LM...Small Craft Advisory until 11 PM EDT this evening for LMZ043-046. && $$ SYNOPSIS...JT/Fisher SHORT TERM...Fisher LONG TERM...Fisher AVIATION...Lewis Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1103 PM CDT Sat Aug 12 2017 .UPDATE... Issued at 1059 PM CDT Sat Aug 12 2017 Updated forecast to drop severe thunderstorm watch. Decreased chances for precipitation over night. UPDATE Issued at 413 PM CDT Sat Aug 12 2017 Updated zones to add severe thunderstorm watch. && .SHORT TERM...(This evening through Sunday) Issued at 249 PM CDT Sat Aug 12 2017 The HRRR would seem to be the most rational model for the storm activity late this afternoon and tonight. A blend of the Canadian, nam and gfs was the basis for chance showers and thunderstorms Sunday. Storm activity late this afternoon and tonight could organize into 3 clusters off the Colo front range, Laramie range and Black Hills/White river valley where a warm front will be located. A blend of the HRRR and HRRR Exp models was the basis for the storm forecast tonight. The RAP model was taking an atypical storm/propagation southwest from Valentine to Imperial and was discarded for this forecast. POPs are limited to 70 percent as some models like the NAM show the infamous "Lincoln County Split" sending storms through Southwest Nebraska and North Central Nebraska north of Broken Bow. This would produce little or no rain across Lincoln and Custer Counties. Storm activity should exit the forecast area 12z-15z Sunday morning but redevelopment is possible across Wrn and Ncntl Nebraska. This is highly dependent on the tracks of the MCS`s tonight. So, POPs Sunday are limited to 30 percent. SPC is placing a slight risk for severe storms across the Nebraska Panhandle for isolated storm development during the afternoon. Winds aloft at 500mb should increase to 30- 40kt late in the afternoon. Temperatures aloft are quite cold today and Sunday, less than 10C at 700mb, and when combined with 30 to 40 kt winds at 500mb and ample moisture, SPC suggested very large hail west of highway 83 late this afternoon and this evening. See the SPC day 1 outlook for additional information. South winds redevelop Sunday and this, presumably, will support highs in the lower 80s with partly cloudy skies. .LONG TERM...(Sunday night through Saturday) Issued at 249 PM CDT Sat Aug 12 2017 The long term forecast period will be characterized by near to slightly below temperatures and a chance for at least isolated thunderstorms daily. By far the best chance for organized widespread thunderstorm activity will be Tuesday evening, when a strong shortwave trough will move east across the Dakotas and Nebraska. A few severe storms will probably occur, but overall shear is rather weak. The bigger threat may be areas of locally heavy rainfall. Really little pattern chance seen this week...as west to northwest flow materializes once again in the wake of Tuesday`s shortwave. The upper level high pressure and associated heat will remain well south of our region in TX and LA. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 631 PM CDT Sat Aug 12 2017 Thunderstorms continue along aand south of a line from KVTN to KAIA. These storms contain large hail. KVTN looks to be on the backside of the system and have left thunder out of the forecast for now. KLBF will see vcts through at least 2z. Line is kind of sporadic and have just carried vcts. Southerly winds to the east of the line and will become light and variable once the thunderstorms get to the east of the station. Some stratus expected around sunrise with MVFR cigs. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Power SHORT TERM...CDC LONG TERM...Taylor AVIATION...Power
Area Forecast Discussion...UPDATED
National Weather Service Spokane WA
854 PM PDT Sat Aug 12 2017 .SYNOPSIS... A cold front will move across the region overnight through early Sunday morning. The system will come with a risk of showers and breezy conditions as well as afternoon thunderstorms across the north and blowing dust across the Basin. Drier, more seasonal weather is expected for the new work week, before temperatures start to warm slightly by the end of the week. && .DISCUSSION... Update this evening to expire/cancel the red flag warnings. The shortwave moving up the Cascades has moved north into Canada. The shortwave moving across the central ID panhandle has produced more exciting results across Idaho county than further north in our forecast area. We are still getting some light reflectivity across the Camas Prairie north into Shoshone county which is likely producing some light rain. The HRRR has been consistent in showing the rain moving north into Bonner and Boundary counties over the next few hours, and we may see an isolated thunderstorm out of that, but not the scattered coverage we were previously thinking. The cold front is moving onto the west coast. It will move over the Cascades around midnight and sweep across eastern WA and north ID through the early morning hours Sunday. Brief light rain is expected with this front. Gusty winds will accompany the front and continue through the afternoon hours as well. /Nisbet && .AVIATION... 00Z TAFS: The shortwave is moving north across the Cascades this afternoon. Convection is firing off across NE Oregon and into SE WA. This may impact KLWS and KPUW through 03Z with thunder...and possible vcsh thu 06Z for KLWS. Some of the hi-res models show convection continuing through the night across NE WA and N ID from 09-13Z, but not impact airports. There will be a gradual improvement to surface vis due to wind speeds, direction and light rain. A cold front will arrive overnight...up to the Cascades ard 08Z and then quickly through the region by 18Z. The front will produce light rain and clear up much of the smoke for Sunday. Breezy winds will accompany the front with winds continuing through the aftn for many locations. && .PRELIMINARY POINT TEMPS/POPS... Spokane 62 77 55 77 56 78 / 10 60 10 10 0 0 Coeur d`Alene 61 75 52 77 51 78 / 20 50 10 10 10 0 Pullman 59 75 49 76 49 77 / 20 40 10 10 0 0 Lewiston 66 83 59 83 59 85 / 20 40 10 10 0 0 Colville 62 78 50 81 50 80 / 10 60 20 20 10 10 Sandpoint 60 75 46 77 45 79 / 20 40 20 20 10 10 Kellogg 59 73 49 74 50 75 / 50 50 20 10 10 0 Moses Lake 64 83 50 82 52 83 / 10 30 0 0 0 0 Wenatchee 65 81 58 82 60 84 / 30 30 10 0 0 0 Omak 64 84 55 83 55 85 / 30 20 10 10 10 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
Area Forecast Discussion
National Weather Service Pueblo CO
751 PM MDT Sat Aug 12 2017 .UPDATE... Issued at 748 PM MDT Sat Aug 12 2017 Updated the POPs for tonight based on current pcpn trends seen on radar and based on HRRR forecast for later tonight. && .SHORT TERM...(This evening through Sunday) Issued at 343 PM MDT Sat Aug 12 2017 ...Severe thunderstorm chances increase into Sunday for the plains... Northwest flow will remain over the area with the next upper level shortwave evident in UT/western Co moving across during the evening and overnight hours. This in combination with afternoon heating will trigger thunderstorms across the mountains, some of which will drift off into the plains during the evening. Of greater note is potential for one or two strong to severe thunderstorms across northern portions of the southeast plains this evening along a sfc trof/outflow boundary. This looks to be a conditional threat however as model soundings show a cap in place across the plains today...though this appears to erode close to the mountains and weaken into the evening north of highway 50. HRRR has been persistent with this solution which lends credence to keeping some pops in through the overnight hours across the plains. This area is under a marginal risk for severe weather and given CAPE values of 1500+ J/kg and 0-6km shears of 40 kts, can`t rule out an isolated severe storm basically north of highway 50 through this evening. Otherwise, activity should generally wind down later tonight. Sunday looks like another active day with higher CAPE and shear across the plains as upper flow aloft increases. Once again, thunderstorms will develop over the higher terrain during the afternoon, however focus will also occur along the surface trof axis across the plains. With less of a cap and the potential for 2000- 3000 J/kg of CAPE, this day will have the greater potential of severe thunderstorms. particularly east of a line from La Junta to Kim. Very large hail, damaging winds and an isolated tornado will be possible into Sunday evening. Even though dew points will remain slightly lower across the mountains, there will still be sufficient moisture for locally heavy rainfall and the potential for flash flooding on area burn scars should these areas be impacted by a stronger storm. -KT .LONG TERM...(Sunday night through Saturday) Issued at 343 PM MDT Sat Aug 12 2017 Not many many meteorological adjustments required from previous meteorological reasoning during the longer with issues continuing to include pops, temperatures, heavy rain/localized flash flood potential as well as intense storm potential at times Latest longer term forecast model soundings, computer simulations and PV analysis indicate that a relatively moist airmass to continue over the forecast district into Monday, with some drying then indicated Tuesday before increasing atmospheric moisture returns from late week into next weekend. Still anticipate that isolated to scattered shower and thunderstorm activity will be noted each day with precipitation generally favoring higher terrain locations during the longer term. Again, some of the stronger storms will be capable of generating heavy rain and localized flash flooding concerns and may also be intense at times. As always, WFO Pueblo will issue hydro/severe weather products as needed. Projected maximum and minimum temperatures during the longer term should hover near mid-August climatological averages in combination with basically low-grade gradient winds and minimal fire weather concerns. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 343 PM MDT Sat Aug 12 2017 VFR conditions expected at the TAF sites this afternoon and evening with brief MVFR cigs/vis possible with isolated thunderstorms which could impact the terminals during the late afternoon and evening. All three TAF sites will carry VCTS for now, though KCOS will see the best chance of thunderstorms through this evening. IFR stratus is likely to develop across the plains again tonight...but majority of forecast model simulations keep it just east of KCOS tonight. This will be a tough call and will have to watch how this evolves over the next several runs. For now will carry a BKN010 layer in KPUB through early Sunday morning. Sunday will carry the risk for stronger storms across the plains, particularly along and east of the I-25 corridor. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...28
Area Forecast Discussion
National Weather Service Springfield MO
703 PM CDT Sat Aug 12 2017 .SHORT TERM...(This evening through Sunday) Issued at 307 PM CDT Sat Aug 12 2017 The batch of showers over the extreme southwest portion of Missouri and southeast Kansas this afternoon is rather weak and is struggling to overcome drier low level airmass advecting in from surface high over the upper Midwest. Stronger storms remain well to the southwest over the Red River Valley where better moisture and low level forcing reside along the stalled front. Further to the northwest...thunderstorms were firing up over the central High Plains in western and central Nebraska...ahead of an upper level disturbance and subtle surface trough. The latest HRRR is not showing much of that activity making it this far to the southeast tonight, but does keep some weak convection associated with the northern edge of the eastern Oklahoma shortwave over southern MO. So for now will continue trend of gradual eastward spread of showers and storms, but if the trend continues...central and west central MO will likely remain dry through tonight. On Sunday...the NAM and ECMWF show another area of precipitation developing along the MO/AR border with the approach of another upper level disturbance moving across the southern Plains. .LONG TERM...(Sunday Night through Saturday) Issued at 307 PM CDT Sat Aug 12 2017 The upcoming week still looks warmer and wetter as the upper level flow shifts from northwest to southwest with a large upper trough moving into the western CONUS. This will lead to lee side cyclogenesis and increasing southerly low level flow...along with several disturbances moving over the region. We will need to watch for the potential for stronger storms on Tuesday and Wednesday as moisture, instability and vertical wind shear increase across the region. A front will set up over northwest Missouri and central Kansas by midweek, but will likely not have much of a southern push to bring it this far south. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 648 PM CDT Sat Aug 12 2017 KSGF/KJLN/KBBG tafs: An upper level disturbance that extends from southeast KS into OK will move east into AR for this period. Dry air will be in place with sfc high pressure extending from IA south into KS/MO which will limit overall rain potential. Very light rain will be possible with the best chances along the MO/AR border. VFR ceilings are expected, but may see some mvfr if enough moisture can saturate the lower levels. Rain (where it occurs) overall does not look to have too much affect on visibility unless an isolated heavier shower occurs. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Terry LONG TERM...Terry AVIATION...DSA
Area Forecast Discussion
National Weather Service San Diego CA
108 PM PDT Sat Aug 12 2017 .SYNOPSIS... A developing low pressure trough near the West Coast early next week will bring a dry and stable west flow aloft, with gusty westerly winds across the mountains and deserts. The increasing onshore flow will build the marine layer, for cooler days as low clouds spread well inland each morning. High pressure returns for the latter half of the week, bringing warmer, but continued dry weather. Daytime temperatures will be below average early this coming week, followed by a return to average Summer conditions for the remainder of the week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... At midday, marine stratus was holding along the beaches of Orange and northern San Diego County. Just inland it was clear up to the mountains where a few cu were popping over the highest terrain in the heat of the afternoon. The sfc pressure gradients was trending weakly onshore but winds were light with only a few sites reporting gusts over 20 MPH. Based on the sfc observations and satellite data, a significant amount of moisture remains over the mountains of San Diego County and the lower deserts. The latest HRRR also has generated convection in the San Diego County Mtns/deserts later today. With that in mind, slight chance POPS will remain in the forecast through today. For the remainder of the CWA it will be dry with marine layer clouds reforming rapidly inland again tonight. The last vestiges of monsoonal moisture will be shunted east of the area through Sunday as westerly flow aloft increases in association with a digging longwave trough over the West. The trough will reach peak amplification over SoCal on Tue before retreating to the NE through early Thu. High pressure will then fill the void aloft, resulting in warming through Fri. A dry W-SW flow will prevail aloft through this period, limiting any chance for a resurgence of the monsoon over SoCal. Meanwhile, onshore flow at the sfc will maintain the marine layer with periods of night/morning low clouds/fog over coastal and western valley areas. Temperatures will be below average to begin the new week, then trend back to around average into the weekend. Looking ahead to next weekend and beyond...The 12Z ECMWF/GFS/CMC operational solutions have a return of weak troughing along the West Coast. This favors near, to slightly below average daytime temps, and keeps any chance for a sustained monsoonal push remote. All things considered, this has been a rather nice stretch of weather for mid August, and it looks like it will continue. && .AVIATION... 122006Z...Coast/Valleys...Through 13/0300 UTC, P6SM vis and SKC, except BKN clouds 1000-1800 ft msl lingering within 3 sm of portions of the coast. 13/0300-1400 UTC, stratus re-developing and moving inland 15-25 sm, with bases around 800-1300 ft msl, tops around 1400- 1800 ft msl, and areas of vis AOB 5 sm. Forecast marine layer inversion strength of around 8 deg C at 13/1200 UTC. Mountains/Deserts...SCT-BKN CU/TCU and possibly some isol SHRA/TSRA over the San Diego/Riverside county mountains and San Diego county deserts during the through 13/0200 UTC, with bases around 8000 ft msl and CB tops to 30000-35000 ft msl. Otherwise, P6SM vis and mostly SKC through Sunday morning. && .MARINE... No hazardous marine weather expected through Thursday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...JAD AVIATION/MARINE...Harrison
Area Forecast Discussion
National Weather Service Topeka KS
603 PM CDT Sat Aug 12 2017 ...AVIATION UPDATE... .SHORT TERM...(This evening through Sunday) Issued at 302 PM CDT Sat Aug 12 2017 Tonight and Sunday Two separate disturbances are impacting the region this afternoon. The first set of southern stream impulses are entering the Texas and Oklahoma panhandle region with widespread showers and thunderstorms, stretching as far north as southern KS. Moisture transport in the low levels is pretty limited given the high pressure in control over northeast KS, so have removed pops for the afternoon in our southern areas. The second impulse currently observed over northeast Montana will gradually shift southeast tonight and Sunday. A sfc front over the Dakotas will serve as a focal point for a cluster of thunderstorms to form across Nebraska during the evening. A veering, southerly low level jet feeds ample moisture into the system, with most of the cams shunting the accumulating precipitation eastward towards Iowa by Sunday morning. Latest runs of the HRRR and the RAP are further west with the convection developing, and therefore track the cluster towards north central Kansas after 06Z. However, the ample dry air in place and weak mid level lapse rates support the models with the cluster dissipating as it reaches the CWA. Have kept low end slight chances across far north central areas. Residual high and mid clouds are expected to spread into the area by the morning. Also removed pops for Sunday afternoon as all cams signal moisture availability is limited by the southern stream wave and mcs rolling through Texas. Similar to today, a mix of diurnal cumulus and high clouds combine with highs in the lower 80s. .LONG TERM...(Sunday night through Saturday) Issued at 302 PM CDT Sat Aug 12 2017 The extended will feature a longwave trough across the intermountain West which will begin to send out shortwaves into the Plains by Tues. SW flow aloft atop a broad area of southerly moist low level flow will set the stage for bouts of convection across the Plains Tues and beyond. ECMWF and GFS both indicate a similar pattern with the usual differences in timing of individual waves. Bottom line is that it looks to be another active and potentially wet week for parts of the region until the trough axis passes (if it does) sometime late week into the weekend. Daytime temps should remain near or just below avg with highs in the 85 to 90 range. && .AVIATION...(For the 00Z TAFS through 00Z Monday) Issued at 603 PM CDT Sat Aug 12 2017 With surface obs and model progs showing a stable airmass over the terminals through Sunday, VFR conditions should prevail. There is a low probability for some ground fog in the morning, so will keep an eye on conditions to see if chances change. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Prieto LONG TERM...Omitt AVIATION...Wolters