Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/06/17

Area Forecast Discussion
National Weather Service Gaylord MI
1015 PM EDT Sat Aug 5 2017 .UPDATE... Issued at 1014 PM EDT Sat Aug 5 2017 Showers and even a few thunderstorms crossing Lake Michigan over the last couple hours have been struggling to maintain their intensity as they encounter a comparatively drier, more stable airmass over northern Lower. The 00Z APX sounding reveals a dry column overhead with a PW around 0.6 inches. So, expect showers to continue to erode the farther east they progress, but a few could brush the lakeshore counties of northwest Lower. Have therefore included a slight chance of showers along the lake for the next few hours. Looking upstream, a few additional showers developing over far western Lake Superior from a weak passing shortwave. The RAP and HRRR carry these weakening showers through the UP overnight, possibly entering western Chip/Mack counties around daybreak if they hold together. Have kept forecast dry for now, but something to monitor. Otherwise some patchy fog overnight with temperatures dropping through the 50s. && .NEAR TERM...(Tonight through Sunday) Issued at 337 PM EDT Sat Aug 5 2017 ...Remaining coolish, some showers on Sunday... High impact weather potential...few non-svr thunderstorms northern lower MI Sunday afternoon. High pressure in eastern KY is extending ridging into the upper MS valley. This ridge separates a departing low in Quebec, and an incoming low in western KS. Diurnal heating, combined with the coolest temps remaining aloft, have contributed to some showers over eastern upper and far ne lower MI. Though that will wane, a stray diurnal shower from upstream could drift into the region. Better chances for rain will play out on Sunday in northern lower MI, as low pressure advances toward the lower OH Valley. As mentioned above, ongoing diurnal showers over far eastern upper and ne lower MI will dissipate quickly this evening. However, additional diurnal showers are firing upstream in ne WI and western upper MI. This activity also won`t have an especially long lifetime. But, with a coolish airmass in place and a warmer Lake MI, these may have somewhat more success in crossing the lake than one would otherwise expect. A stray late afternoon thru mid-evening shower may be needed in parts of nw lower MI. Otherwise, the wx looks largely quite late tonight into the start of Sunday...though with some potential for steepish mid-level lapse rates and the return of 850- 700mb warm advection to allow a stray elevated shower in parts of northern lower. Better chances for rain arrive Sunday, particularly in the afternoon. The incoming low is well to our sw and won`t provide a lot of dynamic support for precip, outside of generally weak warm advection. However, moist advection will be more prevalent, especially below 700mb. This should not be enough moisture (or lift) for widespread cloud cover. So diurnal heating should be sufficient to develop enough instability for lake breezes to trigger convection. MlCape values of around 500j/kg aren`t impressive from a svr standpoint, and in fact getting thunder at all will be a somewhat marginal proposition. But there is certainly enough local forcing/moisture/instability for sct showers, and a rumble/two of thunder. These will be most prevalent in northern lower MI in the afternoon, and away from the stabilizing influence of Lake MI. Min temps on the cool side tonight, upper 40s to mid 50s for most. Max temps most commonly low/mid 70s. && .SHORT TERM...(Sunday night through Tuesday) Issued at 337 PM EDT Sat Aug 5 2017 ...Mostly Dry and Warming... High impact weather potential...none. Surface low tracks up the ohio river valley Sunday night and Monday. Meanwhile, aloft, upper low moves through Ontario, dragging the main trough through the region late Monday. Small but sharp ridge moves through Tuesday. Surface low is quite far south for significant , but models showing 70+% RH in the 850-700mb layer Sunday night with some weak energy moving through northern MI until upper trough goes through. So small chance for lingering showers Sunday night. Monday, daytime heating and cold pool overhead could kick off some isolated afternoon showers south until mid level moisture is stripped away with the upper trough. Otherwise, high moves in Monday night, clearing out skies and helping temperatures Tuesday warm to near normal. .LONG TERM...(Tuesday night through Saturday) Issued at 337 PM EDT Sat Aug 5 2017 Extended continues to look fairly quiet into the weekend, with high pressure overhead most of the time. A weak, elongated boundary could bring some scattered showers Thursday. Details are a little murky into the weekend with rain/storm chances. Seeing signs across guidance for a potential cutoff low to our west. Some are a little faster with it and could affect the area Saturday, some a bit slower and affecting the area Sunday. Will see how it develops in the coming days. Temperatures expected to run near to slightly above normal through the period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 729 PM EDT Sat Aug 5 2017 VFR. Chance for showers, especially Sunday afternoon. High pressure in the Ohio Valley contributing to relatively quiet wx in the region. A small chance that a few showers crossing Lake MI could make it into the MBL and perhaps TVC areas this evening. Better chance for rain arrives Sunday, especially in the afternoon, as low pressure moves east toward the lower Ohio Valley. The best chance for showers will be inland from Lake MI, so APN would see the highest chance of seeing rain. Ongoing w winds will diminish this evening, with winds remaining light thru Sunday with some directional variation. && .MARINE... Issued at 819 PM EDT Sat Aug 5 2017 Gusty winds have diminished this evening, so have gone ahead and cancelled the SCA over northern Lake Huron. Previous discussion follows... Winds/waves will continue to diminish as low pressure moves away from western Quebec. We`ll return to a somewhat more typical late summer pattern, with weaker systems impacting the region. A ridge of high pressure will edge east from the Upper MS Valley, before a low advances east toward the Ohio Valley by Sunday night. A light westerly breeze Sunday will become northerly on Monday. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MK NEAR TERM...JZ SHORT TERM...KF LONG TERM...AM AVIATION...JZ MARINE...MK/JZ
Area Forecast Discussion...Updated
National Weather Service Billings MT
808 PM MDT Sat Aug 5 2017 .UPDATE... Lack of forcing and decent lapse rates has resulted in a quiet evening across the CWA. There is currently just a lonely little convective cell near the Bull Mountains, but the rest of the activity is further south in Wyoming. Thus we have reduced/removed PoP`s for many locations this evening. Weak cool front will slip into the northeast zones overnight and may produce some lower cloud decks and sprinkles or light showers into Sunday morning. BT && .SHORT TERM...valid for Sun and Mon... Water vapor imagery shows NW flow over the region, with a couple features of interest. The first is a weak circulation in northeast MT which is dropping to the southeast. The second is a stronger area of PV in south central Alberta. Energy in northeast MT may help to initiate convection near the MT/Dakotas border over the next few hours, as the HRRR has been consistently showing. Surface front has surged eastward into the western Dakotas, but pressure falls to the west may allow winds to shift back to the east eventually this evening. This boundary may be a focus for tstms so will need to keep watch. As it looks now, any stronger storms look to stay a bit east of our cwa. Further west, cooler easterly winds and a good amount of stratocu has resulted in a capped airmass, and very little is going on to this point. As shortwave approaches from the northwest, some showers or weak tstms are possible mainly this evening. Greatest potential for pcpn will remain in our far east Sunday, east of surface trof, as Alberta shortwave drops thru eastern MT. Ascent will increase thru tonight and into tomorrow, so potential exists for some nocturnal wet thunderstorms east of Miles City and Broadus...again must watch evolution of surface boundary. Have raised pops a bit in Fallon County tomorrow when the PV passes. Further west, activity will be weaker and with less coverage. Temperatures tomorrow will stay well below normal with highs in the 70s. With enough cloud cover and pcpn, places like Baker and Ekalaka could actually struggle to get out of the 60s. Subsidence spreads in from the NW late Sunday and Sunday night as shortwave departs to the southeast. Sunday night should be the coolest night of the current cool spell. Weak shortwave ridging and stable east winds will keep our cwa dry on Monday, with warmer temps (though still below normal). Could see an isolated storm over our southwest mountains Monday afternoon and evening. JKL .LONG TERM...valid for Tue...Wed...Thu...Fri...Sat... Models are in fairly good agreement for the upcoming week. High pressure ridging over the Pacific northwest will result in a northwest flow aloft across our forecast area. This will keep temperatures much cooler than what the area has experienced for much of the past couple of weeks with readings looking to be below normal. Some weak energy gets trapped under the ridge bringing a slight chance for a shower/thunderstorm basically each afternoon/evening. The best timing for showers and thunderstorms looks to be Thursday into Friday when a slightly stronger disturbance within the northwest flow moves southeast out of Canada. Temperatures for the most part wil be in the lower 80s Tuesday through Friday. Hooley && .AVIATION... Skies will be partly to mostly cloudy through the remainder of the night. A weak cool front will slip into the KMLS and KBH areas late resulting in some increase in clouds with a slight chance of local MVFR developing with a light shower. Otherwise, VFR conditions will prevail through tonight. BT && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 054/076 051/080 054/081 056/083 057/085 060/084 059/088 12/T 10/U 01/B 12/T 12/T 22/T 21/U LVM 047/076 046/080 048/080 049/083 050/084 051/084 051/085 11/B 00/U 02/T 13/T 23/T 22/T 21/U HDN 052/078 048/081 052/083 056/084 057/087 059/086 059/089 22/T 10/U 01/B 12/T 12/T 22/T 21/U MLS 055/075 051/080 056/081 055/082 058/085 059/084 059/087 23/T 10/U 01/U 12/T 12/T 11/U 10/U 4BQ 054/076 049/080 053/082 054/082 056/083 058/084 056/087 13/T 20/U 02/T 22/T 22/T 21/B 10/U BHK 052/071 046/077 051/079 050/080 054/081 056/083 054/083 35/T 20/U 02/T 11/B 22/T 22/T 20/U SHR 052/073 046/077 050/078 053/080 053/082 054/084 055/084 13/T 20/U 02/T 23/T 33/T 23/T 31/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Caribou ME
918 PM EDT Sat Aug 5 2017 .SYNOPSIS... A cold front will move through the area tonight with shower and thunderstorms expected this evening. High pressure will build in on Monday before the next low pressure tracks south of the Gulf of Maine on Tuesday morning. && .NEAR TERM /THROUGH SUNDAY NIGHT/... 9:18 PM...A cold front moving into western Maine will move across the CWA and exit the state before daybreak. Showers with embedded thunderstorm will continue to lift north/northeast tonight, and most of the activity should exit the eastern zones by 3 AM. Heavy downpours are expected, and Greenville just picked up 0.45" in the past hour. Severe weather is not expected, and given the relatively fast movement of the system flash flooding is also looking like less of a concern too, but will need to continue to closely monitor over the next few hours as locally some spots could be impacted by a few storms. Made some minor tweaks to the ongoing forecast based on the latest observations, radar, and near term model trends...but nothing significant. Previous discussion... Sfc cold front is now in the Hudson Vly and contg it`s trek to the east. Showers hv mvd into wrn CWA this aftn ahd of s/wv well out ahd of upr lvl trof still mvg thru NY/PA at this time. Breaks of sun hv occurred briefly acrs the region this aftn but SBCAPE is still minimal acrs the state. 0-6km bulk shear still in place and wl lkly get stronger into the evng hrs with 40-45 kts of shear upstream acrs most of New England at this hr. If convection can get organized acrs the area this evng, may see an isold storm produce gusty winds but chcs look pretty slim at this time. Latest HRRR and NAM nest guidance suggest some bowing segments may occur acrs the North Woods arnd 00z tonight then quickly diminish as they run into more stable airmass. Line of convection to the west has produced a quick shot of hvy rain tho upstream radars are only estimating 0.50-1.00 inch in an hr. Wl continue hvy rain wording for early evng as training of any storms that dvlp wl hv the potential to produce hvy downpours but overall amnts wl rmn blo FFG. Expect convection wl slowly diminish aft 03z tonight with loss of diurnal htg bfr diminishing to just showers aft 06z. Cdfnt fcst to bisect CWA arnd 09z tonight, exiting CWA shortly aft 12z. Expect that drier air wl lag slightly bhnd bndry with patchy fog contg until aft daybreak acrs the region. Mins wl dip into the 50s acrs the far NW by mrng but rmn in the lwr 60s acrs ern and Downeast zones. Upr lvl trof wl be swinging thru the state Sun aftn with cldy skies rmng acrs the north along with the chc for showers. Highs for Sun wl be blo normal for this time of year with gusty nw winds expected thru the day. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Sunday night into Monday zonal 500mb flow across the state with cool westerly flow advecting in dry Canadian air. It will be a nice crisp Monday morning with high clouds on the increase through the day as an area of low pressure begins to take shape across the mid-Atlantic. Still some good spread in guidance on the exact track of the mid-Atlantic low as it travels across the Gulf of Maine Monday night into Tuesday morning. The ECMWF and GEM continue to be on the northern edge of the guidance with the NAM/GFS further south. Kept categorical pops going for Downeast as they have a good chance for a soaking rain, but confidence is still low further inland and how far north the rain shield spreads. Still a good chance for .50" rain for the coast at this time, but still enough spread for the low to trend further south. Drying and clearing expected by Tuesday afternoon into Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Forecast confidence is a little below average for Wednesday through Friday, but overall pattern looks to be cyclonic in nature with a broad trough to the north of New England over Quebec province. Frontal boundaries could occasionally impact the region with afternoon showers, but not enough confidence to pin-point location and time. Interior Maine will be favored for shower activity. Overall temperatures will run near to just above average for this period. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... NEAR TERM: VFR acrs northern terminals will drop to IFR tonight in low cigs ahead of frontal bndry. Once cold front moves thru expect cigs to rise to low MVFR aft daybreak. At BGR and BHB expect MVFR to drop to IFR after 02z in low clouds and fog. Cigs will improve to low MVFR after 12z. SHORT TERM: No impacts to aviation operations expected Sunday night through the day on Monday. IFR conditions could be possible for KBHB/KBGR Monday night into Tuesday morning as a coastal low travels across the Gulf of Maine. Clearing expected by Tuesday afternoon. && .MARINE... NEAR TERM: The wind and seas will remain below small craft advisory levels thru the weekend. Areas of fog will impact visibility over the waters tonight through Sun morning before a cold front moves through. SHORT TERM: Offshore westerly flow on Monday expected, becoming southerly Monday night as a coastal low approaches the Gulf of Maine. Low pressure will quickly exit the region by Tuesday afternoon with offshore flow becoming established once again. Seas are expected to remain below SCA for this period. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/Farrar Short Term...Dumont Long Term...Dumont Aviation...CB/Farrar/Dumont Marine...CB/Farrar/Dumont
Area Forecast Discussion
National Weather Service Cheyenne WY
555 PM MDT Sat Aug 5 2017 .UPDATE... Issued at 441 PM MDT Sat Aug 5 2017 Quick update to account for the latest convective trends. Scattered to numerous showers and thunderstorms have evolved from the South Laramie Range eastward into the Pine Bluffs and Kimball areas. These showers and storms will continue eastward through the early evening hours with small hail, gusty winds, and heavy downpours likely. && .SHORT TERM...(This evening through Monday) Issued at 231 PM MDT Sat Aug 5 2017 A few isolated to widely scattered storms developing early this afternoon along the Snowy and South Laramie Ranges and these showers and storms will continue to develop and move SE into northern CO into the early evening. Effective shear values are currently around 35 kt with SBCAPE around 1000 J/kg. This could lead to a few stronger storms with hail and gusty winds being the main threat. Steep low to mid level lapse rates and quite dry sub- cloud layers will promote good downdraft production so wouldn`t be surprised to see a few strong outflows even from weaker showers. The HRRR and NCAR Ensembles have been consistent in showing a complex of showers and thunderstorms developing to our NW and tracking SE along the North Platte valley roughly from Torrington to Scottsbluff tonight. This complex may be aided by some elevated instability and weak lift along a southward moving front, ahead of a minor ripple in the NW flow currently over SW MT and NW WY. Upped POP in these areas tonight to account for consistency in the hi-res guidance. Front will hang up along the mountains Saturday as surface winds become northerly over the plains and eventually back to easterly by late afternoon. After some morning low clouds and fog along with any residual showers from the above-mentioned complex, expect another round of showers and thunderstorms to develop over the higher terrain and track eastward through the afternoon and evening. Still enough shear for a strong to severe storm or two especially with web bulb zero heights a little lower than today. For Sunday night and Monday, models are consistent in ejecting some Pacific energy NE from CA into northern CO by Monday afternoon. Upper diffluence increases especially over the south with some signal of a coupled jet structure aloft. With PW values of 1.0 to 1.3 inches, think widespread showers and thunderstorms, some with heavier rainfall are likely. Upped POP to likely especially south of line from Laramie to Scottsbluff. GEFS ensemble mean precipitation for Cheyenne during this period is around 1.3 inches with decent clustering of at least an inch so think there is a good chance for the area to receive some much- needed rainfall. .LONG TERM...(Monday night through Saturday) Issued at 231 PM MDT Sat Aug 5 2017 Unseasonably cool and unsettled pattern to continue thru at least the middle part of the week. A nearly stationary frontal boundary along the front range courtesy of persistent NW flow will combine with sub-tropical moisture fed by WSW/NNE oriented jet-streak streaming east off the ern Pacific. The result will be continued precip chances, best along the WY/CO stateline and adjacent locations along the I-80 corridor Tuesday and Wednesday. The CWA will be on the north side of the front in an air mass consisting of H7 temperatures in the 6-10C range. These cooler temperatures in combination with thicker cloud-cover will yield high temps that will only reach the upper 60s (above 5000 feet) and 70s Tuesday and Wednesday. Jet energy shifts south Thu-Sat, which should yield gradually drier and warmer conditions. Although even then, the CWA will not be completely dry, just less coverage than early in the week and mainly confined to the afternoon/evening period. High temps look to return to the 80s for most locations by Fri-Sat. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 556 PM MDT Sat Aug 5 2017 Main area of storms this afternoon is situation along and south of the I-80 corridor. Radar shows some development off the northern Laramie Range as well, but that activity doesn`t seem to be holding together well. Expect the southern line of storms to maintain for a couple more hours, and perhaps redevelop on a boundary laying west to east across northern Laramie County. Once this round of storms dissipate after midnight, still think stratus/fog and light rain/drizzle will likely develop at most terminals after 09z where moist upslope flow develops in the wake of thunderstorm outflow. Conditions will slowly improve in the late morning but another round of showers/thunderstorms looks to develop near the mountains in the late afternoon. && .FIRE WEATHER... Issued at 231 PM MDT Sat Aug 5 2017 Left the Red Flag Warning in place for northern and western Carbon County as Rawlins is currently hitting criteria. After this evening, decreasing temperatures and increasing amounts of moisture should limit fire weather concerns at least through early next week. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...DEL SHORT TERM...DEL LONG TERM...CAH AVIATION...RJM FIRE WEATHER...DEL
Area Forecast Discussion
National Weather Service Dodge City KS
607 PM CDT Sat Aug 5 2017 ...Updated Aviation Discussion... .SHORT TERM...(This afternoon through Sunday) Issued at 1230 PM CDT Sat Aug 5 2017 Much hotter temperatures temporarily returning to SW KS this afternoon. Expecting all locations to be well in the 90s before the day is done; already 93 here at the office as of 1230 pm. Starting around 4 pm, expecting scattered thunderstorms to develop along a prefrontal trough, mainly south and east of Dodge City. NAM/HRRR solutions are in good agreement that coverage will favor the SE zones. Bulk shear and CAPE appear sufficient for some modest storm organization, including some possible supercells, mainly SE of a Meade-Larned line. Hail up to 1-1.5 inch in diameter and thunderstorm outflow winds to near 60 mph can be expected from the strongest storms. Convection will likely organize upscale into a loosely organized complex, impacting the far SE zones (Barber county and vicinity) through about 10 pm. Cold frontal passage expected tonight, with winds becoming N/NE across all of SW KS during the late evening. Some gusts of 30-40 mph will occur with the initial frontal passage, although convective coverage along the frontal boundary itself is expected to be minimal. Consensus of short term models shows post- frontal low stratus clouds overspreading all zones through sunrise Sunday. Continued NE winds and cool advection through Sunday morning are expected to prevent widespread fog formation, but certainly can`t rule out some patchy fog with the widespread stratus. Along with WFO Goodland, included some patchy fog in the grids for Sunday morning. Lows Sunday morning in the lower to mid 60s. Sunday...Cloudy (in the morning) and noticeably cooler. Stratus expected to hold through about 10 am, then erode during the afternoon. Given the expected afternoon August sunshine, ignored the cooler MET/NAM guidance, and followed the warmer MAV guidance, with afternoon temperatures ranging from near 80 NE (Hays) to the mid 80s along the Oklahoma border. About a full 10 degrees cooler than Saturday, with NE breezes of 10-20 mph persisting all day. Stable surface high ridge axis expected to prevent thunderstorms across all of SW KS on Sunday. .LONG TERM...(Sunday night through Saturday) Issued at 145 PM CDT Sat Aug 5 2017 Long term forecast will be characterized by much below normal afternoon temperatures, and virtually daily chances for showers and thunderstorms. In fact, it is very difficult to find any time period through next week when there is not at least a chance of showers/thunderstorms somewhere in SW KS. Synoptic pattern changes little through all of next week, with broad 500 mb ridging from southern California to West Texas, and persistent broad 500 mb troughing from the northern plains through the Great Lakes. As a result, moderate (40-50kt) W/NW flow at 500 mb, with embedded, difficult to time, shortwaves will continue through the week. CAPE in excess of 2000 J/kg will be available from time to time. As such, some strong to severe thunderstorms are possible next week, with all global models hinting at MCS production at various times and locations. 12z ECMWF generates 1-2 inches of QPF across all of SW KS through the week, supported with excellent agreement from 12z GFS. With the active and wet pattern, the heat will not be allowed to return. Afternoon temperatures Monday through Wednesday expected to only be in the upper 70s to lower 80s (early August normal is lower 90s). && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 606 PM CDT Sat Aug 5 2017 Based on radar trends and latest HRRR the convection over the next few hours will stay east/southeast of Dodge City and Liberal where a prefrontal trough will be located early tonight. Winds north of this surface boundary will be north northeast at 10 to 15 mph. A surface cold front will drop south early tonight and as it crosses southwest Kansas some low clouds are expected to begin to spread into the area from the northwest. NMM,HRRR, and ARW were all in good agreement with IFR conditions developing behind this front between 09z and 12z Sunday. These low clouds are expected to linger through much of the morning with some improving ceilings developing between 15 and 18z. Last to have VFR conditions will be the Hays area. && .PRELIMINARY POINT TEMPS/POPS... DDC 65 82 62 79 / 20 10 10 20 GCK 64 83 62 76 / 10 10 20 40 EHA 62 83 60 77 / 10 10 40 40 LBL 65 84 64 79 / 20 10 20 20 HYS 64 78 62 76 / 20 10 10 30 P28 68 85 65 83 / 70 10 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Turner LONG TERM...Turner AVIATION...Burgert
National Weather Service Kansas City/Pleasant Hill MO
618 PM CDT Sat Aug 5 2017 .Discussion... Issued at 313 PM CDT SAT AUG 5 2017 Potential dangerous flash flooding will be the main threat in the next 24 hours as synoptic conditions are setting the area up potential training thunderstorms along an elevated warm frontal boundary over our CWA. The Flash Flood Watch will remain in effect through 7AM tomorrow as this entire area will have the potential to have flash flooding depending on where the main line of training thunderstorms sets up overnight. The LLJ this morning developed a NW-SE oriented line of convection with moderate stratiform rain as it pushed through providing a nice soaking rain of around 0.5" for most of the area south of the Missouri River. This event will be the primer for the next more significant heavy rain event this evening as soils will be somewhat saturated over the area. Currently the LLJ has a south to north orientation over eastern KS helping to develop some elevated storms along a WNW-ESE oriented 850mb boundary near Topeka. NWP models have sort of been all over the place with the forecasted QPF totals in amount and location making it difficult to nail down the final QPF maximum locations though Sunday morning. Looking at VWP data it does appear that the RAP, NAM, and NAMnest have all been the most constant solutions with the RAP matching up with the wind profiles at 850mp the best. With this said, these three models as well as the HRRR have indicated the LLJ will ramp up over eastern Kansas around 7pm CDT creating a strong convergent boundary right over the KC Metro area and reorienting the 850mb boundary more W-E. This reorientation is crucial as it places the boundary parallel to the storm motion which increases the likelihood of training convection along the northwest of this boundary. PWAT values between 1.8 and 2" with MUCAPE values between 1000-1500J/kg and plenty of forcing set up a potentially dangerous situations. This boundary appears to stay somewhat stationary over the Missouri River area until just after midnight when it slowly starts to advect to the SSE as the LLJ shifts more SW-NE oriented. Currently we are forecasting widespread 4" of precipitation over the area south of St. Joseph with pockets of 5-6" along the training boundary. There could even be localized areas that see above that if multiple strong storms move over the same area for a period of time. Outside of the flooding threat there is also a chance of seeing some elevated supercells with low Cape but high effective bulk shear after 7pm. The threat is somewhat low for winds or tornadoes with these storms being elevated above the boundary layer, but large hail could be possible with somewhat lower freezing levels around 12kft. The main threat for severe weather would be along the convergent boundary with the strongest forcing. Another issue that leads to the flash flood potential is that the rain storm two weeks ago helped to decrease our flash flood guidance with most of the area below the Missouri River only needing 2-3" in 1, 3, or 6 hours to reach the flash flood criteria. Expect warnings to be issued rather quickly if this scenario does set up as expected and water could rise fast with soils already saturated. Traveling through these heavy rain areas after dark is not recommended as water may be difficult to see on the roads as it rises overnight. Temperatures may not even make it into the 70s today with continual cloud coverage and precipitation inhibiting any type of heating. The surface low driving this event will slowly move to the east Sunday morning helping to drive this precip to the SE and out of the area by Sunday afternoon as ridging and NE flow push back into the area. This high pressure will dominate the area through Wednesday with unseasonably low temperatures below 80 degrees through Tuesday. A weak shortwave pushes through Wednesday creating some chances of precipitation over the area but overall most should stay dry. Temperatures stay cool in the lower 80s through Thursday with mostly nice conditions expected for August. The next real chance for rain will occur Friday as a strong upper level shortwave pushes into the area from the central plains creating another rainy day Friday, although it looks much less of a flooding event than tonight. Ridging pushes back in quickly Saturday making for a decent weekend with mostly dry conditions and high temperatures in the lower to mid 80s. && .Aviation...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 618 PM CDT SAT AUG 5 2017 Multiple hazards will affect air traffic throughout most of the terminals. The first hazard will be persistent thunderstorms that will continue to develop over the region through the first 6 hours of the forecast period. Visibility may be decreased in heavy rain at times to at IFR or below temporarily. These storms will start to move to the SE away from the terminals in the morning, but will be a problem off and on throughout that timeframe. The second hazard will be a low IFR ceiling around 1000ft that looks to persist for most of the forecast period. There may be times that it lifts above IFR with TS are around the station but overall trend will be IFR conditions until Sunday afternoon. If this changes the forecasts will adjust as needed. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...Flash Flood Watch through Sunday morning for KSZ025-057-060- 103>105. MO...Flash Flood Watch through Sunday morning for MOZ028>033-037>040- 043>046-053-054. && $$ Discussion...Barham Aviation...Barham
Area Forecast Discussion
National Weather Service Fort Worth TX
913 PM CDT Sat Aug 5 2017 .UPDATE... The cluster of thunderstorms that were previously tracking across portions of Throckmorton and Shackelford Counties continue to fizzle this evening with the loss of daytime heating. Anticipate that the lone cell northeast of Abilene will continue to suffer a similar fate with increasing nocturnal inhibition, but will leave some very low PoPs near Breckenridge and Cisco for the next hour or two to account for activity spilling into our CWA. Otherwise, have removed the mention of precip from the remainder of the forecast area through 2 AM. Overnight, we`ll turn our attention to convection which is ongoing across the Texas Panhandle in association with a mid-level wave coming out of New Mexico. The 3-km NAM and HRRR both seem to have a decent handle on current trends, and advertise at least some potential for the southern periphery of this complex to back-build towards the Red River late tonight. This seems plausible given the development of a 30-35 kt low-level jet sufficient elevated instability to work with. Opted to introduce a small sliver of 30% PoPs across the immediate Red River Counties where isentropic ascent will be maximized during this time frame. Severe weather looks pretty unlikely with this overnight activity, but some gusty winds and brief heavy rainfall will be possible. The potential for isolated to scattered convection will persist Sunday morning, mainly north of I-20. Carlaw && .AVIATION... /Issued 716 PM CDT Sat Aug 5 2017/ /00Z TAFS/ VFR conditions prevail across North Texas this evening with the exception of a few isolated thunderstorms to the west of the major airports. Currently, one severe storm is slowly drifting east out of Throckmorton county with an additional storm or two to the south of there. This activity is expected to remain to the west of the area tonight and will likely diminish in intensity over the next couple of hours with loss of daytime heating. There is a little more wind shear today than we normally have on an August afternoon, so they could persist a little longer than normal but should still remain to the west of the major airports. VFR conditions are expected to prevail through the overnight hours with southerly winds around 15 kt. We will see an increase in low level moisture overnight although the low level flow itself will veer to the southwest. This should keep any MVFR cigs that develop to the east of the airports through early Sunday morning. For now, we`ll keep VFR conditions prevailing, although we`ll have SCT018 sky conds in for the morning hours. Later Sunday afternoon, as an area of surface low pressure gets closer to the Red River, a frontal boundary will move into southern Oklahoma. This should be a focus for scattered to numerous showers and thunderstorms during the afternoon/evening hours which will likely have an impact on north/west bound departures/arrivals. Shower and thunderstorm activity is expected to increase farther south into the Metroplex late Sunday night and we`ll include a VCTS by 07/04Z. Scattered to numerous showers and storms are expected to continue areawide into Monday. Dunn && .SHORT TERM... /Issued 352 PM CDT Sat Aug 5 2017/ /Rest of today through Sunday Afternoon/ Weak convection continues to slowly develop across the Hill Country and across the Big Country where the axis of low level moisture appears to be greatest. In addition, an ill-defined MCV may be augmenting ascent on its eastern flank as evident by deeper lightning-producing convection. While there is a good degree of uncertainty over the next 24 to 48 hour forecast, this feature and its behavior will likely be a key player in PoP and subsequent sensible weather elements. Convection will likely continue this afternoon and into the early evening hours along and southwest of a St. Jo to Hillsboro to near Athens line, but activity should generally diminish for most areas with the loss of daytime heating. The one exception will be across northwestern and northern zones where activity may be more dynamically driven by the aformentioned remnant MCV to the west. Most hi-res guidance is in fair agreement that a bulk of the nocturnal convection will track eastward through Oklahoma. However, low level wind fields do increase tonight, which could support some backbuilding of convective cells down to the south of the Red River. With that in mind, I`ve maintained and even increased rain chances during the overnight hours into Sunday morning. Severe weather during this time period looks unlikely given the elevated nature of convection. I won`t rule out heavy rain, some very small hail and perhaps some gusty winds, if downdrafts can penetrate the slightly stable PBL. Overnight conditions elsewhere should continue to moderate from previous` nights with increasing 925mb flow, subsequent low level breeziness and increased cloud cover. Late Sunday morning and into Sunday afternoon---several members of the 00 UTC NCAR ensemble...the ECMWF and the last few frames of the Operational HRRR all suggest that convection may be possible for areas near and north of the I-20 corridor. This is somewhat plausible given that convection to the north may put out an outflow boundary and additional southerly flow aloft induces gradual ascent atop this boundary resulting in additional convection through the morning hours. For now, will paint 40 PoPs across extreme northern sections of the Red River Valley with 20 PoPs down towards the I-20 corridor. Additional convection may re- fire tomorrow afternoon along this feature, but it appears most probable across northern and northeastern zones and I`ve confined the highest PoPs to this area with lower rain chances farther south. Storms may approach severe limits during this time as there should be a fair amount of DCAPE necessary for strong to perhaps damaging downbursts. Heavy rain will be possible as convection will generally be slow moving. I won`t rule out a near severe hail threat as well given that shear values will promote multicell storm structures. There will be a potential for some diurnal type convection across southern and eastern zones, but coverage should be fairly low. Where clouds and rain don`t hang tough, we should see some breezy southwesterly winds which should help to keep conditions quite toasty with highs in the mid to upper 90s to near 100 degrees out across western and southwestern zones. 24-Bain && .LONG TERM... /Issued 352 PM CDT Sat Aug 5 2017/ /Sunday Evening Through Saturday/ Overall, not much has changed for the Sunday evening through Wednesday part of the forecast. There is a threat for strong/severe storms Sunday evening and night, and a threat for heavy rainfall Sunday evening through Tuesday and possibly into Wednesday. Low rain chances remain in the forecast for the remainder of the week. As talked about above, some showers and storms may already be ongoing by Sunday evening related to outflow and/or mesoscale boundaries remaining from convection across Oklahoma tonight. However, we expect another complex of storms to develop along a slow moving front to our north and northwest during the late afternoon and early evening hours. Strong and severe storms will be possible during the evening hours with a main threat for damaging winds and heavy rainfall. Some hail near 1" may also be possible. CAPE values in the early evening hours in our northwest counties could approach 3000 J/kg as temperatures soar into the upper 90s. Shear values are a little more uncertain, but the GFS has deep layer shear values near 20 kts which is why the hail threat cannot be discounted. A combination of ample moisture in place with PWATs near 2" and a slow movement to the system will also yield a threat for heavy rainfall and flooding. This complex of storms will drift south and southeast through the evening and nighttime hours, likely weakening overnight as the low level winds decrease in speed and veer to the southwest. Have kept rain chances high Sunday night, mainly across the northwestern half of the region. Widespread rain chances and a threat for heavy rainfall will continue Monday through Tuesday as we remain in a weak northwest flow aloft pattern with an upper level ridge to our west. The models continue to keep the surface front stalled to our north on Monday, but we anticipate it will sink south with convection. In addition, other mesoscale boundaries may be present from the convective complex that could be foci for showers and storms during the day on Monday. Where these boundaries will be located on Monday is too difficult to discern this far in advance, and we will adjust the forecast as needed. Forecast soundings still indicate a threat for strong storms producing gusty winds will be possible Monday afternoon, but that threat appears to diminish some more by Tuesday. Regarding the heavy rain threat, widespread rainfall totals of 2-4 inches are forecast, with the highest totals along and north of Interstate 20. However, a notable portion of those totals are in the Sunday night-Monday time frame associated with the complex of storms. On Monday and Tuesday, the rainfall will not be continuous and is expected to occur in rounds, but the showers and storms will be efficient rainfall producers and slow movers capable of producing at least localized flooding issues. We continue to assess the need for a Flood Watch starting as early as Sunday night, and a Watch may be issued tonight or Sunday morning. By Wednesday, the rain may become more scattered in nature as the front starts to lift north and the upper level ridge starts to build in from the west. Heavy rainfall will still be possible as PWATS remain high for this time of year, and storm motion will be slow. For the remainder of the week, reduced PoPs to 20-30 percent, and confined them to mainly the northern and eastern portions of the CWA as the models are split on how much the upper level ridge will build across the Southern Plains. There is some indication that depending on the location of the upper level ridge, we could be monitoring MCS activity to our northwest each day. There is also some agreement that another front could bring more rain chances next weekend. JLDunn && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 80 96 75 85 74 / 10 20 70 70 70 Waco 77 98 77 87 74 / 20 10 30 70 70 Paris 74 90 73 83 71 / 20 50 60 60 70 Denton 78 97 75 84 73 / 10 30 80 70 70 McKinney 77 96 75 84 73 / 10 40 70 70 70 Dallas 80 97 77 86 75 / 10 20 70 70 70 Terrell 76 95 76 85 73 / 10 30 50 70 70 Corsicana 76 96 76 86 73 / 10 20 30 70 70 Temple 75 96 75 89 73 / 20 10 20 70 70 Mineral Wells 75 96 74 83 72 / 20 20 80 70 70 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Hastings NE
644 PM CDT Sat Aug 5 2017 .SHORT TERM...(This evening through Sunday) Issued at 246 PM CDT Sat Aug 5 2017 A cool summer pattern was in place across our region in a northwest flow regime aloft with upper ridging in the Pacific Northwest and an upper trough along the eastern CONUS. A series of embedded shortwave troughs were embedded within the flow, one of which brought showers and thunderstorms to our area overnight into this morning. Cloud cover today has held temperatures in the 60s and 70s across south central Nebraska with a few 80s in north central Kansas near the warm frontal boundary. As we head into the evening and into tonight, most models suggest our cwa will be on the edge or in between areas of convection. The main focus for storms is expected to be to our south along a frontal boundary near I70, then as the low level strengthens overnight this activity should focus across northeast Kansas and southeast Nebraska given the orientation of the lowlevel jet axis. Additional development is possible along the high plains to the northwest in upslope flow while an embedded shortwave trough translates southeast. This activity is expected to weaken and diminish as it moves southeast late this afternoon and evening, but do have small pops in our northwest/west zones as HRRR holds things together a little farther east than other models. In the end, while the better chances for rain/storms should focus to our west and south/east, have maintained small chances into tonight. Our southern zones in the convective marginal risk area still look to be the buffer of the main convection forecast to the south. Sunday could see a lingering sprinkle in the morning and even potentially drizzle based on the aggressive NAM with it`s abundant low cloud/low level moisture. Do expect a fair amount of cloud cover especially for the first half of the day at least, with potential breaks in clouds as the day goes on. Ultimately temperatures will be dependent upon how much insolation we see and highs in the 70s look on target. .LONG TERM...(Sunday night through Saturday) Issued at 246 PM CDT Sat Aug 5 2017 The pattern through the extended remains cool for August in a continuation of the northwest flow regime as upper ridging is maintained across the Pacific Northwest and a series of upper lows/troughs translate southeast from Canada with the main low pressure systems centered around the Hudson Bay area. This will result in a broad trough across much of the central and eastern CONUS. Surface ridging builds south across Nebraska Sunday night with a fair amount of low cloud cover expected to redevelop across Kansas into portions of Neb. Convection is expected to focus along the high plains in upslope flow with only minimal chances of this activity reaching our western zones overnight or early Monday. Hit or miss chances for showers and thunderstorms remain in the forecast off/on during the worweek with initiation along the high plains with outside chances that this activity will hold together as it migrates eastward. Tuesday and Friday look like the next `decent chance` for showers and thunderstorms with the systems crossing our area. Temperaturewise, look for readings to remain on the cool side and below normal for this time of year. Highs will generally be in the 70s and may top 80 at times, but no significant warmup on the horizon for the next seven days. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday) Issued at 633 PM CDT Sat Aug 5 2017 MVFR or lower stratus and possibly some -DZ will work its way in across the terminals overnight...with generally poor conditions expected to start the day Sunday. Expect generally light easterly winds this evening to subside some overnight...increasing to 10-12 KTS out of the northeast by the mid-morning hours tomorrow. While there may be some showers and possibly even a -TSRA around the forecast area...the probability of a -SHRA or -TSRA impacting either terminal was low enough to exclude the mention of even a VCTS or VCSH at this time. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Fay LONG TERM...Fay AVIATION...Rossi
Area Forecast Discussion
National Weather Service Goodland KS
525 PM MDT Sat Aug 5 2017 .SHORT TERM...(This afternoon through Sunday) Issued at 141 PM MDT Sat Aug 5 2017 Northwest flow remains in place with weak shortwave troughs rotating through the mean flow. Disorganized forcing will be a limiting factor in the short range periods, lowering confidence in shower/thunderstorm coverage through Sunday. Regarding thunderstorms this afternoon-this evening: A stalled front along the western edge of our CWA may act as a possible focus for thunderstorm initiation early, but with a strong CAP in place across much of our CWA early this afternoon there will be a delay in possible onset. Better chances will likely be tied to next mid level impulse (currently organizing over northern Colorado). High resolution models show thunderstorm activity south from where it has initiated in north central Colorado, and moving along frontal zone/CAPE axis in our west by the late afternoon before decreasing in coverage as it moves east during the evening hours. I can`t rule out isolated activity ahead of this in proximity of frontal zone this afternoon/evening, but guidance favors dry conditions until this activity spreads eastward. Additional elevated showers/isolated thunderstorms will be possible overnight, with frontogenetical forcing lingering and weak elevated instability. Deep shear is expected to remain over the region through the evening. RAP analysis is already showing up to 3500 J/KG of SB CAPE and up to 1500 J/KG of DCAPE in our west near this stalled front. Models show adequate instability across our CWA through the evening, so severe threat can`t be ruled out further east. if thunderstorms do develop into this environment there could be an organized severe threat particularly in our west. The question will just be "if". Late tonight-Sunday morning: A backdoor cold front is shown to move over our CWA from central Nebraska late tonight, with increasing low level moisture. Post-frontal BL winds may remain high enough to prevent dense fog development despite strong influx of low level moisture, but fog still can`t be ruled out. Model moisture profiles are showing a deep enough moist layer to support possible drizzle development Sunday morning. I added patchy fog and drizzle to the morning period. Sunday: A stronger shortwave trough is shown to approach the region late afternoon from the northwest, but strongest forcing appears to hold off until the evening. If stratus holds on in the west highs may not warm out of the lower 70s and afternoon shower/thunderstorm chances could be greatly diminished. Deep shear will be in place, so if clearing does occur our western CWA could see enough instabilty for an afternoon severe threat (mainly our eastern Colorado counties). .LONG TERM...(Sunday night through Saturday) Issued at 141 PM MDT Sat Aug 5 2017 West to northwest flow aloft continues throughout the long term period with troughing over southeastern Canada into the Great Lakes and a ridge to the southwest. This pattern results in wet and cool weather for the area. On Sunday night, precipitation chances increase from the west as a stronger shortwave pushes into the region from the Rockies. This disturbance moves across the High Plains through Monday night, keeping showers and thunderstorms in the forecast and generating the best opportunity for precipitation during the long term. The main concern during the Sunday night to Monday night timeframe will be heavy rainfall leading to flash flooding as ample moisture filters into the region and PWATs reach values between 1.0 and 1.5 inches. Shower and storm chances persist on Tuesday as the aforementioned shortwave trough progresses. Wednesday and Thursday appear somewhat drier with periodic slight to low chance PoPs. A disturbance works its way onto the Plains late in the week, which may be the next decent opportunity for some precipitation. However, confidence decreases the further we go into the period due to the uncertainty caused by this weather pattern. Temperatures are anticipated to be below normal. Highs are generally in the 70s Monday and Tuesday before increasing back into the low/mid 80s by Thursday. Lows range from the mid 50s to low 60s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 516 PM MDT Sat Aug 5 2017 VFR to IFR conditions forecast for the TAFs. Main focus is the timing of stratus and how low the ceilings will fall overnight. In the next few hours focus is also on whether KGLD will have any storms or not. Addressing the more immediate item, the question is how far east will the storms move before they run into a stable environment. Am thinking KGLD should be on the eastern limit of any storm activity so placed a VCTS mention in the TAF. The storm activity will end by late evening. Regarding stratus overnight, latest data agrees that conditions will begin to deteriorate at KMCK not long after 6z. Some of the data is suggesting a gradual decline from MVFR to IFR ceilings while other data is suggesting an almost immediate change to IFR. Would not be surprised if the more immediate drop in conditions is what ends up happening. Will have a better idea for 6z TAFS as observations to northeast of KMCK should give a good idea of what to expect. KGLD should remain MVFR, but cannot rule out IFR conditions during the latter half of the overnight hours. Conditions should improve for both sites mid morning as temperatures warm. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JBH AVIATION...JTL
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1048 PM EDT Sat Aug 5 2017 .SYNOPSIS... A stationary front just to our south overnight will return northward as a warm front Sunday through Monday as low pressure moves from Texas across the Ohio Valley. The front will become stationary again across our region through the week, with deep moisture and periods of heavy rain likely. && .NEAR TERM /THROUGH SUNDAY/... As of 1030 PM EDT: Persistent showers and a few thunderstorms continue to develop late this evening just south of Chester County in the eastern Upstate along the stalled surface boundary. The latest HRRR runs bring a few showers northward over the Charlotte region overnight, but this is contradicted by the surface high pressure building over to the north of the region overnight and reinforcing the low level northeasterly flow. This should keep the boundary, and any associated showers, just south of our area through early Sunday morning. Temperatures appear on track with cooler than climo mins expected overnight given the northerly surface winds. Winds will adjust back toward southerly through late Sunday morning and this will allow moisture (which is not far away) to start pushing back northward. Shower chances, with a few thunderstorms, will slowly increase from the south through late in the day. A blend of guidance still looks good for max temps, with values just below climatology Sunday afternoon. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 220 PM Sat: Broad upper troughing will remain in place across the East through the period, with a slight increase in the height gradient expected through the first half of the period, as a short wave moves from the Great Lakes into the Northeast. Short term guidance is in agreement that a series of weak surface waves will develop along the associated frontal zone across the TN/Ohio valleys through the period. Associated with this "cyclogenesis," the models develop anomalously strong SW flow in the lower levels by Sunday night, pushing a warm front and associated deep moisture into the forecast area. Model qpf response is fairly decent Sunday night, and with >1000 muCAPE advertised, we certainly could see some areas of heavy convective rainfall. Pops will be advertised in the 50-70 range Sunday night, with the highest values favored in the SW upslope areas of the Blue Ridge. A brief lull in convective activity is possible through a good chunk of the day Monday, as the warm front is progged to lift quickly north of the area. However, convection originating along the frontal zone to our west will likely encroach on the area later today, while additional activity should initiate over our area within high PWAT/moderate unstable air mass during the afternoon. At least likely pops appear warranted across the entire area, while categoricals will be advertised along the TN border. The wavy/slow-moving cold front is finally progged to sag into our forecast area on Tuesday, warranting another round of likely pops across most of the forecast area. NE flow becoming established north of the boundary is expected to result in max temps a solid 10 degrees below climo across northern area Tue afternoon. (Otherwise min temps will be a little above climo and maxes a little below climo through the period). By the end of the short term period, antecedent conditions will probably be deteriorating, at least on a local basis, after a couple of days of multiple waves of showers and storms. FFGs are quite high due to the recent dry spell and it`s not at all clear at this time what (if any) areas will have the highest chances for hydro issues by mid-week, so we have no plans to include mention of excessive or heavy rainfall in the Hazardous Wx Outlook attm. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 220 PM EDT Saturday: the extended fcst picks up at 00z on Wednesday with a very broad upper trof centered over Eastern Canada and a relatively flat pattern over the southeast CONUS. Over the next couple of days, numerous pulses of weak upper shortwave energy move over the region as the subtropical ridge slowly builds well offshore. By the end of the period, a more amplified upper trof begins to dig down over the northern plains as the upper ridge amplifies over the Western CONUS. At the sfc, a lingering frontal bndy is expected to be just to our south with deep lyr moisture over the fcst area to begin the period. Reinforcing high pressure behind the front will be centered over the Ohio River Valley/Southern Great Lakes. That high will move eastward fairly rapidly and is expected to be offshore by Thursday. This puts us back under a moist, SLY return flow pattern for the rest of the period. As for the sensible fcst precip chances will remain elevated thru the period with high-end chance to low-end likely PoPs each day and broken to overcast cloud cover thru the period. At this point, the main concern is still the potential for isolated to widespread flooding. The latest GEFS standard anomaly PWAT fcsts have values 1 to 2 standard deviations above normal thru the period. With the ample cloud cover expected, high temps should remain below climatology with low temps right around climo. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... At KCLT and Elsewhere: The stalled frontal boundary will remain southeast of the terminal forecast area through the overnight hours. Some slightly reinforcing northeasterly flow will develop overnight before winds toggle around to the southeast and then southwest through the day on Sunday, and the boundary returns north as a warm front. Moisture will also return over the warm front through Sunday, but with mainly just developing VFR ceilings throughout. Scattered late day showers should arrive from the south, but nothing more than PROB30 is needed after 21Z at the SC TAF sites for now. Outlook: The boundary will continue its northward trek Sunday night through Monday. Moisture will steadily return over the region. Unsettled conditions will then set up through most of the week as the boundary remains nearby, moisture pools overhead, and a series of upper level waves pass by. Restrictions will be possible with any showers and thunderstorms. Fog and low clouds may develop each morning around daybreak, mainly in the mtn valleys but also in areas that receive heavy rainfall the day before. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 95% High 100% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 100% High 100% High 100% High 100% KAND High 100% High 100% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JPT NEAR TERM...HG SHORT TERM...JDL LONG TERM...JPT AVIATION...HG
Area Forecast Discussion
National Weather Service Wilmington OH
1001 PM EDT Sat Aug 5 2017 .SYNOPSIS... Dry conditions are expected tonight as high pressure slides off to the east. Precipitation chances will then be on the increase Sunday afternoon into Sunday night as a low pressure system moves east across the region. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... With the setting of the sun, cumulus clouds have dissipated this evening. What`s left is a plethora of high clouds, poised to move across the Ohio Valley during the overnight hours. Given coverage and dense nature of the high clouds, have boosted sky cover upward, favoring a mostly cloudy overnight. HRRR even suggests a few sprinkles or a shower possibly across the southwest CWA late tonight, but think this is overdone and have left forecast dry. Clouds will likely impede fog formation overnight, so only have patchy fog near river valleys in southern Ohio. For temperatures, favored upper 50s across the north to lower 60s near the Ohio River/northern Kentucky. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Short wave energy will move out of the mid Mississippi Valley on Sunday and across the upper Ohio Valley through Sunday night. Ahead of this, the low level flow will back around to the southwest through the day on Sunday allowing for some developing isentropic lift. The airmass will start out fairly dry but as we gradually moisten up through the day, this will lead to an increasing chance of showers from west to east across the area, primarily through the afternoon hours. Will range highs from the lower 70s northeast to the upper 70s across the southeast for Sunday. An associated surface low will lift east northeast across the region Sunday night. The models continue to vary on their timing and placement of this low, with the ECMWF father north than the GFS/NAM solutions and there is also quite a bit of spread with the various ensemble solutions. Nonetheless, expect increasing pops as we head into Sunday night as a low level jet pivots up into our area ahead of the low. Will trend toward the model blend with the highest pops across our north. Instability will remain pretty meager but this may be enhanced somewhat with the increasing dynamics moving in so will allow for some embedded thunder Sunday night. It does look like there could be a swath of heavier rain along and to the north of the low track as PWs push up in excess of 1.5 inches but it is difficult to pin down exactly where that will be at this point. && .LONG TERM /MONDAY THROUGH SATURDAY/... Potent low pressure carried by a westerly flow aloft will be moving across Ohio on Monday. Widespread showers and embedded thunderstorms are expected. Relatively high atmospheric moisture content coupled with a deep warm cloud layer may result in heavy downpours. Overall flood potential may be mitigated by progressive nature of the system. Rain chances diminish by Monday afternoon as the low tracks rather quickly east toward the Atlantic Coast. After an upper trough axis moves east early Tuesday, a confluent zonal flow aloft producing an elongated area of surface high pressure will result in dry weather Tuesday through Wednesday. The chance for showers and thunderstorms is forecast to return Thursday and Friday in the increasingly humid circulation around the departing high. Saturday may see more organized thunderstorm activity as forcing and moisture coalesce ahead of the next area of low pressure. In a pattern featuring below normal geopotential heights, periods of clouds, precip and cold advection, temperatures are expected to be below normal to start, reaching the upper 70s Monday and Tuesday. A modest rebound to the near normal lower 80s is anticipated for Wednesday through Saturday under increasing insolation and slight warm advection. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Still have a few cu lurking around early this evening, which should dissipate within the next couple of hours, but infrared satellite imagery indicates plenty of high clouds set to stream across the Ohio Valley tonight. Presence of high clouds will limit fog formation overnight, but certainly can`t rule out a brief MVFR visibility reduction at fog-prone KLUK late tonight. Westerly flow aloft will continue to transport cirrus across the area on Sunday. Much of Sunday should be dry, but by early evening would expect some rain (and eventually lower cloud bases, although initially still VFR) to begin encroaching on KDAY/KCVG. OUTLOOK...Showers and isolated thunderstorms are possible Sunday night and Monday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL NEAR TERM...BPP SHORT TERM...JGL LONG TERM...Coniglio AVIATION...BPP
Area Forecast Discussion
National Weather Service Jacksonville FL
801 PM EDT Sat Aug 5 2017 .UPDATE...Showers have been decreasing in coverage this evening...except for recent increase over southeast Marion Co and Flagler Co. HRRR appears quite overdone in activity over the next few hours. Will keep low POPs going a few more hours far southern counties and along coast...with chance POP for next hour se Marion and srn Flagler counties. Low temp forecast looks good...generally lwr-mid 70s. && .AVIATION...VFR conditions next 24 hrs. Shower/t-storm chances tomorrow low enough to keep out of TAF. && .MARINE...No significant changes in next CWF issuance. A ridge of high pressure will remain just south of the waters this weekend before moving over the waters early next week. Winds tonight will be light southerly direction. Winds Sunday will be mostly south in the morning then become southeast in the afternoon and evening at 10 to 15 knots. Early next week winds will be south to southeast 10 to 15 knots. Seas 2 to 4 feet. Scattered mainly late afternoon and evening showers and thunderstorms. Rip Currents: A persisting long period groundswell warrants a Moderate Risk at the northeast Florida beaches through Sunday. && .PRELIMINARY POINT TEMPS/POPS... AMG 72 91 73 92 / 10 40 30 30 SSI 76 87 77 88 / 20 20 20 20 JAX 74 90 75 92 / 10 20 20 30 SGJ 75 87 77 89 / 10 20 10 30 GNV 73 90 74 92 / 10 20 10 30 OCF 74 91 75 92 / 10 20 10 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Wolf/Zibura/Elsenheimer
Area Forecast Discussion
National Weather Service Miami FL
803 PM EDT Sat Aug 5 2017 .AVIATION...TAF sites remain dry and VFR overnight with SE winds 3-7kts. East coast seabreeze kicks in for ATLC sites after 14Z with SE winds 11-14kts. Moisture looks higher tomorrow, so there will be a potential for SHRA/TSRA with seabreeze development. For now, trends suggest this would be just inland of sites so will keep mention out of TAFs. For KAPF, Gulf breeze kicks in around 17Z with WSW winds 10-12kts. Similar to today, TS developing just inland of KAPF, potentially moving back overhead during afternoon hours. && .UPDATE... Isolated showers and storms that had developed earlier over the far western interior, along the Gulf sea breeze boundary, are now starting to dwindle. This trend will continue through late this evening with the loss of diurnal heating. Light southeast winds will persist along the east coast metro region with light and variable winds elsewhere. With a a warm atmosphere still in place, many minimum temperatures along the east coast metro will only drop to the low 80s, tying or breaking a few high minimum temperatures records. && .PREV DISCUSSION... /issued 404 PM EDT Sat Aug 5 2017/ DISCUSSION...Latest IR imagery is nearly a mirror image to 24- hours ago, with a line of convection extending from the northern Gulf to the Carolinas and patchy fair weather cu over southern Florida. A 594 dm upper level high pressure cell continues to sit stagnant over the CWA, responsible for the subsidence and very warm weather. A few moderate showers have developed north of Naples in Collier County, where the Gulf sea breeze has been allowed to advance and collide with southeast flow. Short term models, including the latest runs of the HRRR and Hi- Res WRF, erupt additional activity over portions of northern Collier, Glades, and Hendry counties through early this evening. This activity is progged to diminish by nightfall. Heat index values have reached the 100s and are pushing criteria for some spots, but not widespread enough to consider an advisory. None the less, a very toasty afternoon for South Florida. Tonight, record or near record high minimum temperatures will be in jeopardy, especially along the east coast metro region. The enlongated upper level ridge of high pressure will remain between South Florida and Bermuda tomorrow, as a surface high pressure cell sits below. Thus, expect another round of persistent brisk southeast winds. Also of note, GFS time height cross sections indicate increasing moisture from the surface to around 15,000 ft agl, reintroducing a slightly higher shower and thunderstorm chance to the region. Early to mid next week: A similar synoptic pattern will lead to persistent southeast flow with weak waves of increased moisture through the period. Maximum temperatures will range from average to slightly above average for this time of year. Long range models show a Topical Upper Tropospheric Trough (TUTT) reaching the area from the east during the Wednesday night/Thursday timeframe. If this scenario plays out, expect increased instability along with deeper atmospheric moisture. This would lead to a higher chance of showers and storms by late in the week. MARINE...Generally good boating conditions will prevail across the local waters into early next week under a moderate east to southeast flow of 10 to 15 knots. Winds over the offshore Atlantic waters may occasionally reach 20 knots Sunday night, mariners can expect some choppy waters. Seas will be 3 feet or less over the next several days, except up to 4 feet at times in the Gulf Stream, along with isolated to scattered showers and storms, especially during the nighttime hours. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 81 92 82 92 / 10 40 30 40 Fort Lauderdale 83 92 82 91 / 10 30 30 30 Miami 82 93 81 91 / 10 30 30 30 Naples 77 95 77 93 / 20 30 20 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && UPDATE...27/JT AVIATION...88/ALM
Updated for 00Z aviation forecast discussion.

&& .SHORT TERM...(Tonight through Monday night) Issued at 308 PM CDT Sat Aug 5 2017 Current MCS (Mesoscale Convective System) moving through mature phase at this time over the southern half of Missouri. There is some evidence of upper level saturation in the GOES-16 lower to upper level water vapor into northern sections of southeast MO and Southern IL. This may be more fruitful for overnight convective activity though, given the weaker shear aloft. Utilized significant weighting of the NAM-WRF family of short term guidance, especially the 4km NMM/ARW versions, as well as the CAM producing HRRR guidance to reflect the decay of the MCS into southeast MO/southwest IL this evening as the current low amplitude shortwave (embedded in the broad cyclonic flow) de-amplifies with time. Another wave is expected to move in later tonight and reinvigorate the lapse rates to generate more precipitation over the same area, before slowly moving east on Sunday and Sunday night. Was previously concerned with heavy rain potential over a larger area on Sunday earlier in the week, but the focus of any excessive rain will be marginalized into smaller pockets of heavier convection, mainly where low/upper level thermal/pressure field gradients are coincident in space, especially over southern Illinois and southeast Missouri. As the frontal boundary moves through the area on midday Sunday, phased in with a progressive and channeled vorticity wave aloft, the greatest surface reflection (surface low pressure development) will occur over southern sections of the WFO PAH forecast area. SPC has this area under marginal risk of severe thunderstorms for Sunday (Day 2). Limited organized convection will occur, supporting better updrafts for hail/wind production into the evening hours, especially over west Kentucky. Although there is still a faster west-northwest upper level flow at mid-levels into Monday, deeper layer moisture is lacking. The flow during the day becomes more zonal, retarding the overall movement of the convective activity away from the southern border of west Kentucky until Monday afternoon and evening. This may provide a secondary maximum of accumulated precipitation for the weekend/early week system across west Kentucky. .LONG TERM...(Tuesday through Saturday) Issued at 308 PM CDT Sat Aug 5 2017 At the start of the extended period, a drier airmass and high surface pressure will be in place over the Midwest, with northeasterly winds prevailing across the PAH forecast area. Meanwhile, a quasi-stationary frontal boundary will lurk just to the south. Depending on the model solution, our region may be dry, or rather wet, through mid week as an inverted sfc trof develops across our region. There should be some associated moisture convergence/lift with this feature. Model consensus suggests that we will have scattered showers and tstms, mainly in the afternoons/evenings, primarily over western KY and adjacent parts of southeastern MO/southwestern IN. The unsettled pattern will continue into the weekend, with broad cyclonic mid level flow continuing. Difficult-to time impulses in the flow will be responsible for on-and-off shower and tstm activity. This activity should pick up as the flow aloft becomes more cyclonic in response to a digging shortwave over the western Great Lakes. In addition, low level winds should gain a more southerly component. Expect near seasonable temps during the extended period, with slowly climbing dewpoints through the 60s. && .AVIATION... Issued at 620 PM CDT Sat Aug 5 2017 Mid/high clouds will continue to increase from the west today and we will be seeing a gradual increase in the chance for rain. This initial MCS has eroded quite rapidly as it approached the terminals late this afternoon. The main time for widespread activity will be after 06Z-09Z and most of the day Sunday, there will be scattered showers and storms around. Ceilings/cigs should be VFR for the most part aside from a heavy shower or storm. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$
Area Forecast Discussion
National Weather Service Shreveport LA
1010 PM CDT Sat Aug 5 2017 .UPDATE... Remove pops for rest of tonight and beef up pops I-30 09-18Z && .DISCUSSION... Radar has dropped off all of the diurnal activity for the evening and we have wiped pops from the previous issuance for the overnight hours for most of us. We have a intro of pops for Mc Curtain county 09-12Z and have increased to likely there 12-18z and much of area N of I-30. New WPC QPF has been loaded through the day tomorrow. The HRRR has been persistant on arrival right around 11-12z and has slowed at tiny bit. The new Nam is a tad slower, but remains consistent with it`s 18z run. Wish we had the new GFS its 12Z was well in across Mc Curtain 12 hours ago. /24/ && .PREV DISCUSSION... /issued 639 PM CDT Sat Aug 5 2017/ AVIATION... VCTS conditions possible across MLU/LFK through 06/02Z. VFR conditions to prevail through much of the night with MVFR ceilings possible across area terminals around daybreak. A decaying convective complex to possible bring VCTS conditions across TXK/ELD around 06/16Z. Otherwise, south winds around 5 knots tonight to increase to around 10 to 15 knots on Sunday. Strongest winds will mainly be across TYR/GGG with gusts to around 20 knots. /05/ PREV DISCUSSION... /issued 302 PM CDT Sat Aug 5 2017/ DISCUSSION... Weak frontal boundary nearly stalled just south of I-40. Lower to mid 70 dewpoints to prevail across area south of this boundary. Convection across southern portions of area has remained very isold and very weak, and will likely not even hold together until sundown given current trends. Will leave in isold convection south of I-20 thru early eve only. By late tonight, outflow convection will likely generate over eastern OK and western AR and edge swd, possibly reaching portions of cwa north of I-30 by late tonight. Progressive development swd with 30 to 40 kt mainly zonal flow aloft and low lvl winds 15 to 20 kts, will begin to increase pops swd by Sunday night. These winds may translate to sfc, so that Sunday may be the only day we consistently see southerly wind speeds in excess of 10 mph. Upper ridging remains to the west, but still captures west TX, into central TX, will help maintain frontal position. A stg shortwave Mon night into Tue will interact with the still near stnry frontal boundary and may bring heavier rainfall totals, mainly to northern cwa. Pcpn water values around 2.25 inch and with some training possible, a few locations may see locally heavy rainfall. Aftn temps in the mid to upper 80s may also be seen across mainly northern portions of area as well due to the rain and clouds. By mid week the front completely washes out, but residual moisture to continue isold to sct convection across area./07/ && .PRELIMINARY POINT TEMPS/POPS... SHV 75 93 77 88 / 10 40 40 60 MLU 73 91 76 89 / 20 40 30 60 DEQ 72 88 73 84 / 10 60 60 70 TXK 74 91 75 86 / 10 50 60 70 ELD 73 91 75 87 / 10 50 40 60 TYR 76 92 77 87 / 10 40 40 60 GGG 75 92 77 88 / 10 40 40 60 LFK 75 93 78 88 / 20 30 30 60 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 24/07/05
Area Forecast Discussion
National Weather Service Las Vegas NV
830 PM PDT Sat Aug 5 2017 .SYNOPSIS...A decreasing trend in thunderstorm coverage is still expected through next week with dry conditions returning by mid week in most areas. Storms remain possible from Las Vegas north to the southern Great Basin on Sunday and then limited to the far northern reaches of the forecast area on Monday and Tuesday. Normal temperatures will return under mostly clear skies Tuesday and beyond. && .UPDATE...Convection continued to die off this evening over southern Inyo County and in and around the Spring Mountains. The latest HRRR keeps any new development north and east of these areas. I updated to remove mention of thunderstorms for the rest of tonight in those areas. Convection in Lincoln County had been weakening considerably for a bit but appeared to be pulsing back up at this time. HRRR continues to spread activity south through Lincoln and central Nye Counties into northeast Clark and northern Mohave Counties. Therefore I left thunderstorms in the forecast there. -Harrison- && .PREV DISCUSSION... 201 PM PDT Sat Aug 5 2017 .DISCUSSION... It has been a rather slow start for thunderstorm development today. Storm activity through 1 PM has been limited to central and northern Mohave County and the Sierra and White Mountains. Except for the far northern reaches of the forecast area, 1-1.5 inch PWATS point to plenty of available moisture around the region. Thus far, the thermodynamic profile suggests a down day for San Bernardino County, the southern portions of Inyo County and the southwestern portion of Mohave County. SPC mesoanalysis shows weak to moderate instability in the Sierra, northern Inyo and the southern Great Basin, with the most unstable conditions over southern Lincoln, Clark and the northern half of Mohave County. Strong capping aloft has limited development to this point but with mostly clear skies and plenty of sunshine to heat the surface, this is expected to erode by mid afternoon. Later this afternoon into the evening hours, a decent early August jet of 50-60 kts noses into the northwest forecast area, providing support for enhanced storm development in that region and across the southern Great Basin. The airmass in this region is somewhat drier and the risk for strong, potentially damaging winds is enhanced. Expect less shower/thunderstorm coverage heading into Sunday and Monday. Weak to moderate instability is forecast on Sunday over Inyo, Esmeralda, Nye, Clark and Lincoln counties...shifting northward on Monday as the airmass stabilizes over southern Inyo, southern Nye and Clark counties and a weak disturbance aloft keeps chances going in northern Inyo, Esmeralda, central Nye and northern Lincoln counties. Other than a storm or two brushing northern Lincoln County mid-late in the week, conditions should be dry and stable. Temperatures remain below normal Sunday and Monday but then warm to near or slightly above normal Tuesday-Saturday. .LONG TERM...Sunday through Friday Precipitation chances become more limited by the second half of the weekend as drier air works into the area. In addition, by Sunday night that vort max finally lifts away from the area and weakens. The previously mentioned trough on the West Coast does push toward the area sunday night and Monday, so kept in some chances for showers and thunderstorms. Instability will be limited and PWATs will be decreasing however, so precipitation should be isolated to scattered at best, mainly over the higher terrain. By Tuesday, better ridging and much drier air arrive, and we should go dry everywhere. Think this dry and warm pattern should continue through the rest of the week. && .AVIATION...For McCarran...Thunderstorms later this afternoon are expected to be confined to the mountains, with an outside chance of erratic shifting winds at the terminal due to outflow. Otherwise, expect fairly typical diurnal winds, with light easterly winds shifting to southerly in the afternoon and southwesterly in the evening. Drier and hotter weather can be expected for much of the upcoming week. For the rest of southern Nevada, northwest Arizona and southeast California...Storms are expected roughly north of a line from Pearsonville to Las Vegas to Wikieup. The main threats will be heavy rain with mountain obscuration and erratic gusty winds. There is some potential for strong winds across the southern Great Basin later this afternoon into the evening. A gradual drying trend is expected to continue into the upcoming week, with thunderstorm chances being pushed a bit farther north. && .FIRE WEATHER...A gradual drying trend will continue through next week. A chance for thunderstorms through this evening over the southern Great Basin, with heavy rain, strong winds and lightning possible. Storm activity will begin to favor the higher terrain beyond Sunday. Even drier conditions are expected to push in next week, with only isolated thunderstorms expected across the southern Great Basin and higher elevations of Mohave County. Temperatures will be warming to near normal by Monday and continuing through the period. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. This afternoon`s primary focus area for thunderstorms will include the Spring Mountains, the Sierra, Inyo County and the southern Great Basin where wind damage and/or flooding reports may be needed. The focus area shifts to Lincoln County and northern Mohave County this evening. && $$ DISCUSSION/AVIATION...Salmen For more forecast information...see us on our webpage: or follow us on Facebook and Twitter