Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/05/18

See below for an aviation forecast discussion for the 00Z TAFs.

&& .SHORT TERM...(This Evening through Wednesday Afternoon) Issued at 322 PM CDT Tue Sep 4 2018 Cold front has made its way to the James Valley this afternoon while a short wave trough was shearing northeastward out of Nebraska. Therefore, showers and storms were beginning to expand on radar and this should continue into the early evening across mainly the eastern cwa. This lift and subsequent showers/storms will quickly end through the late evening as the cold front moves east. Otherwise, canadian air will be making its way into the region through tonight and encompass the area through Wednesday. Expect sunny skies, much lower humidity, less winds, and cooler temperatures on Wednesday. Temperatures will be 5 to maybe 10 degrees below normal in the upper 60s and lower 70s for highs. .LONG TERM...(Wednesday Evening through Tuesday) Issued at 322 PM CDT Tue Sep 4 2018 Surface high pressure will scoot across the region just to our north Wednesday night, with the center of it over northern MN by 12Z Thursday. Although, there will still be enough influence of this high over the eastern CWA to bring light winds and mostly clear skies. Have therefore dropped lows tomorrow night a few degrees over the eastern CWA, more towards MET/MAV numbers - and bottomed out KABR as well. A dry pattern looks to set up from middle week into the first part of the weekend. It appears there will be a period of a fairly tight pressure gradient Friday and Saturday, so have increased wind speeds above that of SuperBlend, which are typically too low in these scenarios. Went more towards MOS values. Precipitation chances don`t enter the forecast again until the latter half of the weekend when it appears shortwave energy will be tracking across the area. Of course this far out, there are timing issues to deal with, so have left inherited POPs alone for right now. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 638 PM CDT Tue Sep 4 2018 A cold front is just about to clear KATY. The low level cold air advection and dry air advection is working to scour out the "sub- VFR" low clouds, with just a few more hours of sub-VFR cloud potential at KPIR and KATY. KABR/KMBG should be in a VFR flying condition for the next 24 hours, with KPIR/KATY joining them by 06Z. There is still the potential for a stray shower or thunderstorm to move through KATY terminal airspace for the next hour or so, and then KATY should be joining KPIR/KMBG and KABR in a dry TAF valid period as stable/dry surface high pressure builds in from the north. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...Mohr LONG TERM...TMT AVIATION...Dorn
Area Forecast Discussion
National Weather Service Birmingham AL
801 PM CDT Tue Sep 4 2018 .UPDATE... MESOSCALE UPDATE. && .SHORT TERM... The forecast remains on track with only minor adjustments to rain chances. The latest radar depiction from MOB/Mosaic has Gordon circulation showing up south of Fort Morgan early this evening. Some banding features have pushed northward into southern Alabama and have interacted with a few convergent boundaries in the easterly flow. NHC`s latest Advisory has Gordon at 70 mph and continuing on its northwest course. Gordon will make landfall later tonight along the central Gulf Coast. SPC`s RAP analysis has the boundary layer starting to stabilize over Central Alabama with SBCAPE dropping to 1000 or less, although there is still a bit higher MLCAPE values around. BULK Shear and Helicity values continue to remain highest south of Central Alabama. A few storms tried to spin earlier but since have weakened. There was quite a moisture gradient depicted between north and south Alabama, with equal differences in shear values. Typical tropical systems contract the strongest rain bands toward the center at night. But we also have this system interacting with land overnight. The good thing here is that the course appears to be non deviating and the strength is forecast to remain nearly the same before weakening after landfall. Model guidance has been consistent too with much of the convection on the north and east side of the overall circulation. Similar to the previous forecast, the non-zero tornado threat overnight into Wednesday still looks rather low. SPC has parts of southwest and west central Alabama in a Marginal outlook. Will continue to hold off advertising this threat until landfall and see how the shear is affected. Wind gust potential between this low southwest and the high off to the northeast will increase the gradient wind potential. This also appears to remain below and advisory criteria at this time. Our southwest counties can tolerate some decent rainfall and flooding is also not anticipated at this time. 75 Previous short-term discussion:Through Wednesday afternoon. Tropical Storm Gordon is behaving with respect to the forecast track, and no significant changes were made to the short term portion of our forecast. Showers should continue develop on the outskirts of Gordon this afternoon, mainly across our southern counties. Some of the stronger cells could contain lightning, and we may have to monitor any cells with rotation as the edge of the stronger wind field brushes our far southern counties. As Gordon moves ashore tonight, the swath of heaviest rain should remain southwest of our forecast area. However, bands on the eastern side of Gordon should be far enough east to affect our western areas through Wednesday afternoon. If Gordon tracks more toward the eastern edge of model guidance, this would place stronger winds aloft over our western counties, resulting in a non-zero tornado threat Wednesday morning into Wednesday afternoon. Confidence is too low to mention this potential in the HWO. .LONG TERM... Wednesday Evening and Thursday. The evening and overnight hours on Wednesday will likely include lingering effects from Gordon as tropical moisture remains in place across our CWA. PW values could still range ~2.2" in counties west of I-65, particularly near the MS/AL border, as central Alabama becomes wedged between this moist airmass and drier air to our east via upper-level ridging. This anticyclonic feature has been positioned across the eastern US and will orient a west-east moisture gradient across the state as mean RH values continue to drop Thursday afternoon. With southerly flow now in place, diurnal heating should spark off scattered thunderstorms after ~18Z and continue into the evening hours. Best PoPs will remain in the west/southwest where the best moisture content remains. The eastern part of the forecast area will be drier overall with PWs ~1.6", and exhibit mostly sunny skies Thursday. Still expecting seasonally normal temperatures with highs in the upper 80s and lower 90s. Friday through Sunday. By Friday, Gordon should have little impact on our weather as remnants should continue to head northwest towards the Missouri Valley. Ridging along the East Coast will struggle to be as prominent, though will persist overall. The Polar Jet, well into Canada at this time, tries to move a bit southward along a low amplitude trough approaching Nova Scotia and weakens the anticyclone between this and a westward moving upper-level low currently south of Bermuda. We should see a drier day on Friday (20% PoPs) as deep layer moisture remains low within southeasterly flow with no significant forcing for ascent. Have slightly increased PoPs for the weekend as result of better moisture values via a transition to southerly/southwesterly flow on Saturday and into Sunday to 30 and 40 percent, respectively. This develops ahead of a trough axis moving across the Great Plains which transports any Gordon remnants to the northeast through the Great Lakes region by the end of the weekend. Overall, diurnally forced afternoon showers and thunderstorms will dictate our precip chances through this period. Monday and Tuesday. Upper and mid-level flow across our area and the southeastern CONUS remains very weak throughout the long-term. The Polar Jet stays well to our north, though some smaller/weaker shortwave features could move across the US and help to enhance storms activity. Upper-level ridging makes an attempt to build across the West Coast/Desert Southwest after the weekend, but flow aloft looks to stay mainly deamplified and zonal across the country. Thus, generally keeping chance PoPs for afternoon scattered convection as there will be no reasonable changes in our airmass throughout the period and sufficient boundary layer moisture remains in place. High and low temperatures should remain around our climatological norms as we head into the next work week with no significant weather impacting our area at this time. 40/Sizemore && .AVIATION... 00Z TAF Discussion. Tropical Storm Gordon tracking northeast and should make landfall along the Mississippi Coast later this evening. Scattered showers and thunderstorms on the northeast quadrant of Gordon will impact south Alabama thru the overnight hours. VCTS will impact KMGM thru 01z, with mainly showers thru the remainder of the night impacting KTOI, KMGM, KTCL. Once Gordon moves into southern Mississippi, showers and thunderstorms will increase in coverage on the eastern side of the weakening system, mainly impacting areas west of I-65. Outside convection, no cig or vsby issues thru 06z. Low cigs will likely impact all Central Alabama sites starting arnd 06z at KTOI and spreading northwest thru 12z. IFR cigs will likely be confined to KTOI, with cigs 1000-1500 feet agl at other sites. Cigs will slowly rise after 14z, becoming VFR by 18z. 58/rose && .FIRE WEATHER... Highest rain chances will be across southern portions of the area today, shifting towards western portions of the area late tonight through Thursday as Gordon passes southwest of the area. There are no fire weather concerns at this time. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 73 88 71 90 70 / 30 20 10 30 10 Anniston 73 88 71 90 70 / 40 20 10 30 0 Birmingham 74 86 72 91 72 / 30 50 20 30 10 Tuscaloosa 75 86 72 90 72 / 50 80 30 40 20 Calera 73 85 71 88 71 / 50 60 20 30 10 Auburn 72 86 71 87 70 / 40 30 10 30 0 Montgomery 74 87 72 90 72 / 60 70 20 30 10 Troy 73 87 71 89 70 / 50 60 10 30 10 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
327 PM MDT Tue Sep 4 2018 .SHORT TERM...(This evening through Wednesday) Issued at 302 PM MDT Tue Sep 4 2018 Main focus for the next 24 hours will center on the fog potential overnight and early Wednesday morning for the Laramie Mountain Range Summit area. Fog, some possibly dense could cause travel impacts along I-80 between Cheyenne and Laramie overnight. cooler temperatures expected tomorrow with more clouds and higher terrain showers expected. Isolated showers and thunderstorms are occurring across the higher terrain of the Snowy Range this afternoon as a nebulous shortwave trough exists across the Rocky Mountain Range with just enough help from surface instability near 500 J/Kg. This activity should decrease in coverage through the late evening and overnight as boundary layer cools. A weak cold front passed through the region this morning with north winds as a result this afternoon. The beginnings of post-frontal stratus are appearing in the northern Panhandle and as we cool through the overnight, this stratus layer should advance southward across much of the High Plains of WY/NE. Winds will pivot more easterly and with upslope flow in a cooler and more saturated environment, areas of fog and low clouds look likely up against and in the Laramie Range. Higher elevations of I-80 near the summit could experience reduced visibilities from 3am to 9am. Will need to monitor this situation closely for a dense fog advisory. Clouds will remain intact much longer Wednesday and thus a cooler day is expected across the High Plains. Skies will be more clear farther west and the combination of greater instability and a more focused shortwave trough should allow for another round of showers and thunderstorms over the Sierra Madre and Snowy Ranges in the afternoon. .LONG TERM...(Thursday through Monday) Issued at 209 AM MDT Tue Sep 4 2018 Not much change from the previous long term forecast. A wavy Frontal zone and broad upper level trough will continue to linger over the area Friday and Saturday before an area of high pressure moves across southern California. Guidance is not well established on the specifics of the forecast beyond days 1 and 2. Temperatures are likely to fluctuate given the presence of the frontal zone and increased likelihood of showers and thunderstorms. Cold front that will move through Saturday will likely bring cooler temperatures through the weekend and the start of the new week. Rain chances are also likely to increase in the post frontal upslope airmass. Next Week zonal flow develops bringing a few shortwave troughs overhead and continuing the more active period. Guidance is not convergent on any particular solution, thus, forecast confidence is low. Climatology and the latest guidance does however suggest a more cool and wet period with rounds of showers and thunderstorms and below average temperatures each day. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1127 AM MDT Tue Sep 4 2018 Low ceilings are still rising across the NE Panhandle TAF sites and should see general improvement back to VFR this afternoon. Other concern for this afternoon will be the development of showers and thunderstorms mainly east of KLAR. For the overnight period, the RAP and SREF have been showing low ceilings across the NE Panhandle again and between KLAR and KCYS. MVFR to IFR ceilings possible with further refinement in later forecast. && .FIRE WEATHER... Issued at 302 PM MDT Tue Sep 4 2018 Gusty north winds are occurring this afternoon after the passage of a weak cold front but relative humidity values remain elevated in the 30 and 40 percentiles with the small exception of far southwest Carbon County. Values there are near or below 20% but winds are much calmer at or below 10 mph. Limited fire weather conditions will continue through the next several days as southeast winds return Wednesday and keep moisture content high while winds will remain below critical thresholds. Scattered showers and thunderstorms will be of concern over the higher terrain Wednesday and lightning ignitions will need to be monitored for given the drying fuels as energy release component values start to climb above normal once again. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...JSA LONG TERM...AL AVIATION...WM FIRE WEATHER...JSA
Area Forecast Discussion
National Weather Service Dodge City KS
508 PM CDT Tue Sep 4 2018 ...Updated Aviation... .UPDATE... Issued at 341 PM CDT Tue Sep 4 2018 Given radar trends, with training, heavy rain producing thunderstorms from Great Bend down to the NE Texas panhandle, have issued another flash flood watch for the eastern CWA (Barber, Comanche, Edwards, Kiowa, Pawnee, Pratt, Rush, Stafford). The watch will be valid through 7 am Wednesday. Obviously, many areas in these zones are saturated or flooded, and the potential for dangerous runoff is very real as thunderstorms continue to train north. && .SHORT TERM...(This afternoon through Wednesday) Issued at 1143 AM CDT Tue Sep 4 2018 Southerly moisture plume continues over SW KS as of midday, although the radar is clear of echoes, and satellite imagery indicates more breaks in the cloud cover compared to yesterday. The added insolation will yield CAPE upwards of 2000 J/kg late this afternoon, and scattered convective redevelopment will occur. The latest HRRR iterations favor this happening across the western zones after 4 pm, west of US 83. This activity will likely drift eastward to at least US 83 through this evening. A more organized convective cluster is expected this evening and tonight across NW Kansas, along an advancing cold frontal boundary. 12z NAM suggests the majority of this convection will remain in NW Kansas (WFO Goodland`s CWA), before the convective remnants drift south with the front late tonight or early Wednesday. Maintained higher pops and the flash flood watch for the northern zones through tonight, but confidence is low. 12z NAM, HRRR and various other CAMs keep most of the heavy rain and flooding potential north of our CWA. With time tonight, the cold front will sag south, with a shift to N/NE winds of 10-20 mph. At least some shower activity and isolated thunder will accompany the frontal passage, as well as persist behind it into Wednesday morning. Stratus and/or fog will again reestablish Wednesday morning, with low ceilings and areas of reduced visibility. Maintained scattered rain showers and isolated thunder in the grids for Wednesday, in the cool cloudy post frontal airmass. Kept thunder mention isolated with little CAPE and a cool stable boundary layer. Temperatures on Wednesday will clearly be below normal; the question is how much. Forecasting afternoon highs in the 70s for areas along and north of US 50, with lower 80s confined to the Oklahoma border. Cool NE winds and cool advection will combine with persistent stratus, such that northern counties may struggle into the lower 70s. If stratus persists daylight Wednesday as the NAM suggests, than clearly the coldest NAM solution will be correct. Cool surface high pressure ridge axis will continue to build south into SW KS through Wednesday evening. This evolution will eliminate surface-based CAPE, and greatly limit elevated instability, such that the prospects for thunderstorms and further flooding will be greatly reduced. .LONG TERM...(Wednesday night through Tuesday) Issued at 145 PM CDT Tue Sep 4 2018 The cloudy, cool wet weather pattern will persist Thursday and Friday, with limited sunshine, afternoon temperatures well below normal, and scattered showers and isolated thunder. As the previous forecast shift mentioned, instability (even elevated) will be limited to nil during much of this time. Still, isentropic lift over the cool stable boundary layer warrants scattered/chance category pops that the model blends generate. With the lack of deep convection, the threat of flooding is expected to end. Thursday looks particularly cool, as 12z NAM/ECMWF depict strong high pressure ridging from eastern Nebraska wedging into SW KS. Models suggest stratus and NE winds of 10-15 mph will persist all day Thursday, with only lower 70s forecast (mid 70s along the Oklahoma border). 12z MET/MAV guidance only have a high of 72 at Dodge City Thursday (about 15 degrees below normal). Clouds, NE winds, and cool surface ridging will hold firm through Friday, with more pleasantly mild temperatures and free air conditioning. 12z ECMWF consistently depicts the remnants of tropical cyclone Gordon in far SE Kansas Saturday morning, recurving into the westerlies across Missouri Saturday afternoon. Gordon will act as a catalyst for a weather pattern change for SW KS, as the cyclone pulls the trough axis east of SW KS, and subsidence encourages a clearing sky. Dry weather will prevail by the weekend, with afternoon temperatures returning to the 80s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 508 PM CDT Tue Sep 4 2018 Another complicated TAF package, including convective potential, a frontal passage tonight, and low stratus behind the front through much of Wednesday. Ongoing convection as of 22z should remain primarily east of DDC. Additional thunderstorms are expected to develop this evening mainly west of a GCK-LBL line. Finally, organized convection is expected north of a GCK-HYS line during the 03-06z timeframe, along an advancing cold front. Broadbrushed VCSH/VCTS, given uncertainty of convective placement. The cold front will sag south through the airports through 12z Wed, with a shift to N/NE winds of 10-20 kts. Additional showers are likely with the frontal passage, and persisting behind the front through Wednesday. MVFR stratus is expected to persist much of the daylight hours Wednesday at all airports. && .PRELIMINARY POINT TEMPS/POPS... DDC 66 78 63 74 / 70 50 40 50 GCK 64 76 61 72 / 60 40 40 40 EHA 62 78 58 75 / 40 30 40 40 LBL 65 80 60 75 / 40 30 40 40 HYS 65 73 62 70 / 70 60 40 40 P28 69 83 66 76 / 60 60 40 40 && .DDC WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Wednesday morning for KSZ030-031-043- 044-046-065-066-079>081-089-090. && $$ UPDATE...Turner SHORT TERM...Turner LONG TERM...Turner AVIATION...Turner
National Weather Service Eureka CA
237 PM PDT Tue Sep 4 2018 .SYNOPSIS...A very gradual cooling trend is expected through the end of the week. Increasing coastal cloud cover can also be expected as the marine layer deepens. No rainfall is forecast for the foreseeable future. && .DISCUSSION...Today`s weather very closely resemble yesterday`s as little changes are being observed in the synoptic flow aloft. Only subtle changes to the broad scale weather pattern will result in a very gradual cooling trend through the remainder of the week. These changes will be most felt across northern areas...particularly interior areas of Humboldt and Del Norte Counties. This will be due to the passage of series of progressively stronger cold fronts through the Pacific Northwest, which will not produce any rain in California but will help to suppress temperatures. Not only this, but a steadily deepening marine layer will also help to carry cooler temperatures farther inland through the end of the week. However, while this cooling trend will be rather pronounced in these northern areas, this trend will be much more muted across more southern and interior areas like Mendocino and Trinity counties, where afternoon high temperatures will continue to climb into the upper 80s and low 90s each day for the next week. Conditions along the coast will remain characteristically mild, and will likely not deviate much from the low 60s for afternoon highs. There is likely to be an increase in marine clouds, however, particularly tonight through the end of the week along the immediate coast. In any case, little to no rainfall can be expected anywhere for at least the next week. /BRC/JT && .AVIATION...Similar to yesterday`s weather conditions continued across the North Coast today. Morning stratus at the coast mixed out in the late morning. However, the Mendocino Coast remained overcast with marine layer tops 1500-2000 feet. Note: A (MVFR) smoke layer drifted across the CEC airport in the afternoon. 24 Hour Taf period (thru THU afternoon): Stratus may spill around Cape Mendocino into Humboldt Bay. Even so, model guidance has morning LIFR/IFR conditions with even lower CIGS/VIS possible at the main air terminals. Interior areas remained mostly VFR other than continued wildfire smoke affecting some locations. UKI was an exception today as low clouds advected into the UKI/Russian River Valley where IFR/LIFR occurred for a couple hours starting around 7 am. HRRR model guidance indicated low cloud advection breaching the Sonoma and Mendocino border again Thursday morning. With light south winds at UKI, expect that some clouds may seep into the airport proper. Therefore, will go with at least scattered stratus in the A.M. /TA && .MARINE...Forecast remains on track with gales (north) or hazardous seas (south) continuing for a few more hours. Advisory level seas will persist over the southern inner waters into the evening and over the northern inner waters until around midnight (this has been extended a few more hours versus the previous forecast). Winds will continue to gust to near gale force near and downwind from Point Saint George into this evening. Northerlies will continue through the work week (with occasional S flow reversal near the coast). However, speeds are forecast to diminish below advisory criteria by Wednesday area-wide. N winds over the S outer waters are forecast to increase again to advisory criteria by late in the week. /SEC && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 9 PM PDT this evening for PZZ450-455. Gale Warning until 5 PM PDT this afternoon for PZZ470. Hazardous Seas Warning until 5 PM PDT this afternoon for PZZ475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Hastings NE
711 PM CDT Tue Sep 4 2018 .SHORT TERM...(This evening through Wednesday) Issued at 355 PM CDT Tue Sep 4 2018 The rain from last night and this morning has all but moved out of the local area, and skies have cleared pretty substantially across portions of central Nebraska. Thunderstorms are currently developing over west central Nebraska and will generally move southeastward into the forecast area this evening through tonight. The SPC introduced a marginal severe risk for these portions of this area. The RAP indicates 1000-2000 J/kg of CAPE, but the shear is relatively minimal. This would be supportive of "pulse" type and multicell storms, and a few could have strong to marginally severe wind gusts. The flash flood watch was extended earlier today, as models bring at least some of these thunderstorms into the southeastern portions of the forecast area that has received 3-7" over the past 3 days. In these areas, even 1-2" could lead to additional flooding concerns. The passage of the upper trough and surface front will lead to a drying trend through the day on Wednesday, although we could still see a few showers redevelop across our southern areas during the afternoon and evening. Stratus and northeasterly winds are expected to limit high temperatures to the upper 60s and low 70s on Wednesday. .LONG TERM...(Wednesday night through Tuesday) Issued at 355 PM CDT Tue Sep 4 2018 Drier air should allow low temperatures to dip into the 50s and low 60s Wednesday night, with only low-end chances for a few showers or storms in the area. The forecast remains fairly similar Thursday through Friday, as the upper level flow pattern remains zonal to slightly southwesterly. There will be daily chances for showers and storms, but we shouldn`t see anything as heavy as early in the week. On Friday night into Saturday morning, another weak trough is forecast to move through the area. This may bring a bit of an uptick in precipitation chances again, before generally drying things out for the rest of Saturday. The passage of this trough will mark the beginning of a bit of a warmup as we head into the weekend, highs on Sunday are forecast to reach the mid 70s to low 80s and should approach 80 degrees Monday and Tuesday. Unfortunately it appears that "pesky" chances for showers and storms will continue through this period as well...especially as another trough moves into the area early next week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 647 PM CDT Tue Sep 4 2018 We`ll have very little surface winds this evening through tonight and thus will be calling for winds to generally be light and variable until we see northeasterly winds behind a trough passage Wednesday morning. Even then the wind will remain light into Wednesday. We will once again have to watch out for thunderstorms with heavy rain, which will be scattered across the area this evening into early Wednesday morning. The best chance for showers and thunderstorms will be between 9 pm this evening and 7 am Wednesday. Ceilings will likely fall into the low end MVFR or possibly IFR range behind the surface trough Wednesday morning. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Flash Flood Watch through Wednesday afternoon for NEZ064-074>077- 082>087. KS...Flash Flood Watch through Wednesday afternoon for KSZ005>007- 017>019. && $$ SHORT TERM...Mangels LONG TERM...Mangels AVIATION...Wesely
Area Forecast Discussion
National Weather Service Grand Junction CO
555 PM MDT Tue Sep 4 2018 .SHORT TERM...(Tonight through Wednesday night) Issued at 255 PM MDT Tue Sep 4 2018 The upper level trough just won`t move and with that, the forecast won`t change much either. As we`ve been saying all week, the trough will keep the atmosphere unsettled and as weak disturbances move through, instability gets released and causes some showers and thunderstorms to form. H7 winds today were generally out of the north until you reach the San Juans and then they become south to southwesterly. This wind shift has kept areas up north drier than down south and is one of the reasons precipitation has been favored over the San Juans. This is being borne out today with radar imagery showing a large swath of showers and storms generally over the San Juans and areas west. A bit of convection has fired over the Book Cliffs and central mountains but, so far, nothing too impressive. Available CAPE is also fairly low across the area except the San Juans. Everything`s going according to plan so made some relatively minor changes to the forecast generally for the overnight hours. The HRRR and NAMNEST showed a marked decrease in convection so followed suit with the forecast. Tomorrow, activity looks to increase as all models have picked up on a small area of circulation moving over the region. Aside from the disturbance, upper level flow becomes generally southerly allowing the deeper moisture down south to advect northward. As this is occurring, CAPE values increase for much of the area especially over the higher terrain with some maxima over the Flat Tops, Book Cliffs, and along the Continental Divide noted. Looking further up in the atmosphere, divergence aloft values are about the same as we`ve seen lately though areal extent increases across much of the area. Plenty of ingredients are in place for an uptick in convection so yet another day of showers and storms expected. .LONG TERM...(Thursday through Tuesday) Issued at 255 PM MDT Tue Sep 4 2018 The polar front jet finally gets going during the long term period as an embedded 120+ kt jet streak approaches the west coast. This movement will cause the trough to finally start shifting eastward. However, we`ll still have to deal with some convection both Thursday and Friday as enough residual moisture will remain in the atmosphere and will still be worked on by the trough as it starts getting shunted to the east. High pressure off to our southwest will start building in over the weekend though passing disturbances to our north will flatten it. Speaking of, one of the disturbances may drift overhead Saturday night into Sunday morning bringing some precipitation to the northern valleys but confidence not very high at the moment so slight chance PoPs look good. As the high builds in, temperatures will start increasing reaching 3 to 5 degrees above normal for much of next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 550 PM MDT Tue Sep 4 2018 Showers with embedded thunderstorms will continue to drift westward off the higher terrain, generating outflow boundaries and impacting some TAF sites with gusts to 35 kts at times depending on where the storms and outflows are tracking. Otherwise, winds will be fairly light with weak winds aloft. This activity should continue through about 02Z with VCTS common at TAF sites along and south of I-70 corridor before dissipating after sunset. Scattered to broken clouds will linger around as the low pressure trough remains over the area. Storms are expected to redevelop after 17Z over the higher terrain again on Wednesday with better coverage and better chance of some storms impacting the valleys late in the day. Expect mainly VFR conditions to prevail with occasional MVFR in heavier showers. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...TGR LONG TERM...TGR AVIATION...MDA
Area Forecast Discussion
National Weather Service Green Bay WI
645 PM CDT Tue Sep 4 2018 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Wednesday Issued at 218 PM CDT Tue Sep 4 2018 The latest RAP analysis and satellite/radar imagery show a warm front stretching across the Upper Peninsula, and a cold front extending over far northwest MN and central SD early this afternoon. Where skies have cleared south of the warm front, temps have risen into the middle 80s with juicy mid 70s dewpoints. Plenty of instability within this airmass (SB capes 2000-3000 j/kg) for scattered showers and storms through early this evening. Not out of the question that a severe weather threat will develop late this afternoon over parts of central into east-central WI as the atmosphere continues to destabilize. Damaging winds will be the main threat with any storms develop. Meanwhile a plume of deep moisture is extending from the western Gulf to the Upper Mississippi Valley. Shortwave activity over Nebraska is helping generate a band of showers and storms within this deep moisture plume. As this deep moisture interacts with the cold front, instability, and shortwave activity, severe weather and flash flood chances are the main forecast concerns. Tonight...The cold front will slowly move to the southeast into northwest WI late. Ahead of the front, a shortwave trough over the Plains and a wave of low pressure will travel northeast across west-central to north-central WI from late evening through overnight. A few strong to severe storms are possible early in the evening to mid-evening as ample diurnal instability interacts with 25-35 kts of deep layer shear. Central WI has the higher shear so believe the higher threat of severe weather will occur there. After this initial period of convection, a large swath of showers and storms are expected to push into central and north- central WI late this evening. Strong fgen forcing within the right entrance region of a jet streak to go along with very good moisture transport via a 50 kt low level jet will lead to the high potential of heavy rainfall. Most short range guidance is in good agreement placing the axis of heavy rainfall from western Marathon to Florence county, where a 2 to 4 or 3 to 5 inch rainfall is possible. Issued a flash flood watch earlier this morning for parts of central and all of north-central WI. Given the strength of the low level jet and low level helicities associated with the surface low, may see an isolated damaging wind threat develop along the southern edge of the heavy rainfall, where elevated instability above 1000 j/kg will persist through the overnight hours. Wednesday...The heavy rainfall will be tapering off and exiting the area to the northeast and east during the morning hours for the most part. A few showers may linger into the early afternoon over east-central WI. With the cloud cover, morning showers and a north wind, temps will be cooler and range from the upper 60s in the north to middle 70s south. .LONG TERM...Wednesday Night Through Tuesday Issued at 218 PM CDT Tue Sep 4 2018 Relatively quiet weather is anticipated during the extended period. Canadian high pressure is expected from Wednesday night through Saturday, along with pleasant, near-normal temperatures. Forecast confidence is lower later in the weekend. The 00z ECMWF brought the remnants of Tropical Storm Gordon into the region, along with a good chance of rain south and east. However, the 12z ECMWF has fallen more in line with the latest GFS, and keeps the system well to our south before shunting it off to the east. For now, will just carry small pops south and east Sunday into Sunday night, and see how the models trend in upcoming days. A weak cold front may also bring a small chance of showers to north central WI Monday into Monday night, but that is a low confidence proposition too. && .AVIATION...for 00Z TAF Issuance Issued at 644 PM CDT Tue Sep 4 2018 Scattered showers and thunderstorms will continue across the region through mid evening, with generally VFR conditions outside of the precipitation. Ceilings and visibilities will lower later tonight as a large area of showers and thunderstorms arrives form the west. IFR conditions are expected over most of the area from midnight through 12z or a little later. A cold front will move pass by around midday tomorrow and be followed by clearing skies during the afternoon. && .GRB WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Wednesday afternoon for WIZ005-010>013- 018>021-030-031-035-036. Beach Hazards Statement from 4 AM CDT Wednesday through Wednesday afternoon for WIZ022-040-050. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......RDM
National Weather Service Jackson KY
855 PM EDT Tue Sep 4 2018 .UPDATE... Issued at 855 PM EDT TUE SEP 4 2018 Precip has died out and a quiet night is expected. Obs have been blended into the forecast, with no substantive changes. UPDATE Issued at 527 PM EDT TUE SEP 4 2018 Based on radar trends, have expanded a 20 percent POP over more of the area for the next hour or two. && .SHORT TERM...(This evening through Wednesday night) Issued at 330 PM EDT TUE SEP 4 2018 18z sfc analysis shows high pressure in place over eastern Kentucky with significant ridging aloft. In fact, with the 5h ridge maxing out overhead this afternoon it appears to have capped our convective development through the afternoon unlike the previous days. Cannot rule out a stray shower or storm through sunset, but coverage will likely be below isolated. The cu field is much flatter than what we saw yesterday and Sunday even over the higher southeast terrain with locations well to the west and northwest seeing the best build up. Have raised PoPs a tad in these areas on the fringes of the CWA and still allowed for a 15% PoP in the south through 6 pm but that may be overkill. Anyways, the heat and humidity are as advertised with readings reaching the upper 80s and lower 90s again this afternoon while dewpoints are up in the lower 70s yielding heat indices in the 95 to 100 degree range many places. Will leave the mention of this (and the small storm chances) in the HWO for the remainder of the afternoon. Winds, meanwhile, are mainly light and variable across eastern Kentucky. The models remain in good agreement aloft through the short term portion of the forecast. They all depict the slow breakdown of the 5h ridge over the area through Thursday morning. While far eastern Kentucky should still be dominated by this ridge, to the west energy spinning out of the mid levels of Gordon will seep into the area lowering heights and limiting the suppression of the anomalous 5h high. With the models in better agreement on this development this afternoon than 24 hours ago confidence is higher in at least western parts of the CWA seeing some impact in the form of increased convective potential - and not necessarily just during the diurnally favored times. Given the model agreement have gone with a blend as the starting point with a lean on the higher resolution HRRR and NAM12 for details. Sensible weather will feature a scant amount of convection into the late afternoon before dissipating toward sunset early this evening along with the bulk of the clouds. For tonight, this will mean another ridge to valley temperature split - though small due to the high dewpoints as well as some river valley fog towards dawn. Without the main protective shield aloft more convection is expected to develop by midday on Wednesday continuing into the evening - also limiting the magnitude of the heat - though still quite warm and humid. The cloud cover and small chances - though sub 15% - for convection Wednesday night will likely limit the fog development as well as the temperature differences. Used the CONSShort and ShortBlend as the starting point for the forecast grids, per the usual, with some minor temperature adjustments - warmer Wednesday and slightly cooler in the valleys tonight. As for PoPs, again adjusted them down outside of the diurnally favored times - but allowing for up to 30% in the southwest on Wednesday afternoon - also down from the blend. .LONG TERM...(Thursday through Tuesday) Issued at 252 PM EDT TUE SEP 4 2018 Models are in generally good agreement heading into the upcoming weekend, with lower confidence developing over the weekend and into next week, especially regarding the remnants of current tropical storm Gordon. The upper level ridge will continue to slowly break down into Saturday as the upper level flow starts to become more zonal over the Ohio river valley. This coincides with a cold front that will slowly push southward across the region into Saturday. This frontal zone may or may not reach eastern Kentucky. However, plenty of surface moisture will continue to yield increased afternoon/evening shower and storm chances. We should continue to see relative lulls through the overnight and early morning hours each day through Saturday. As the boundary stalls this weekend, exact placement of the boundary will be key as moisture from the remnants of tropical storm Gordon start to interact with the boundary. With flow becoming fairly parallel to the frontal zone, potential for locally heavy rain will exists in the vicinity of wherever this front sets up. Models are generally keeping that heavier rain axis to our north, but any shift southward could lead to more of a concern. The low center will eventually strengthen again into early next week with a trough axis working its way across eastern Kentucky. This may be a slow moving axis as the steering winds are not all that perpendicular to the boundary. Thus, a local heavy rain threat could exist with the boundary crossing the area into next week. The boundary should eventually shift southward by the middle of next week, but due to the expected slow movement this could linger around a bit longer. With the increased rain chances and the ridge breaking down, the warm temperatures we have seen recently will take a step backwards this weekend into next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) ISSUED AT 855 PM EDT TUE SEP 4 2018 VFR conditions were present at the start of the period. Fog will develop in valleys containing large streams overnight, and bring localized VLIFR conditions, but the fog is expected to have little or no impact at TAF sites. Fog will dissipate on Wednesday morning, and scattered showers and thunderstorms will develop in the afternoon. Coverage should be a little bit greater than on Tuesday, but the probability at any given point/time is not high enough to warrant inclusion in TAFs. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...GREIF LONG TERM...KAS AVIATION...HAL