Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/18/18

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
422 PM AKDT Tue Jul 17 2018 .ANALYSIS AND UPPER LEVELS... An upper long wave trough evident on water vapor is moving southeast across Southcentral Alaska this afternoon. Showers have started to develop over the Susitna Valley, Talkeetna Mountains, and Copper River Basin. These areas will see some isolated thunderstorms. Subsidence under a building upper ridge over the eastern/northern Bering Sea is producing widespread stratus and patchy fog across much of the Bering Sea and portions of the Kuskokwim Dela and Bristol Bay. A weakening low center over the southern Bering Sea and leading front, extending to the eastern Aleutians is producing light rain, stratus, and fog across the Aleutians. && .MODEL DISCUSSION... Models in the east are in generally good synoptic agreement. However, there are some significant model differences which develop with a front and weak low which moves to the western Aleutians Wednesday and Thursday. Otherwise, fog and stratus will be the main challenges out west and warming temps and drying conditions in the east. && .AVIATION... PANC...VFR conditions and light winds will persist. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... (Tonight through Friday) Showers and isolated thunderstorms have once again developed this afternoon, as daytime heating has allowed some weak instability to develop per the latest RAP analysis showing lifted indices in the -1 to -4 range, with 100 to 400 J/kg of SBCAPE across the Mat-Su Valleys, Copper River Basin, and Kenai Peninsula. The most prominent storm was located west of the lower portions of the Little Susitna River, with this storm having remained fairly organized and likely producing some small hail. However, that`s been about it thus far concerning any convection. This convection has been aided by a second short-wave trough that followed yesterday`s disturbance, with it brushing mainly the northern and eastern portion of the area. This increased cooling/ascent may allow for some uptick in precipitation coverage over the next few hours, before precipitation diminishes overnight as subsidence behind the departing wave takes hold. Otherwise, the main weather feature will be a short-wave ridge of high pressure building across Southcentral, with some difference in the models regarding how strong of a ridge develops. The GFS current forecasts 500 mb heights topping out near 576 dkm, where as the ECMWF is more robust with these heights approaching 580 dkm. The subsequent difference shows up in the 850mb thermal fields with temps in the 10 to 14 deg. C range. What this means for us is our current forecast highs of the upper 60s to upper 70s may need to be increased somewhat if the higher heights/warmer 850 mb temps verify in later model runs. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)... Ridging will remain over southwest Alaska into Friday as its axis slowly shifts east. This setup should keep rain away from the area and allow for some breaks in the clouds. Tonight, fog will form along the coast and advect into southwest Alaska from weak onshore flow spreading through many coastal locations and some areas further inland. The fog will then dissipate Wednesday morning. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)... The low in the southern Bering will drift slowly to the southeast moving across the eastern Aleutians tonight. It will bring more rain to the islands in the area through much of Wednesday until it tracks further into the North Pacific. However, southerly flow for the Alaska Peninsula will bring continued rain for much of the week. Further out west another system is moving towards the western Aleutians. Its front will move in Wednesday and then slowly push east through the rest of the week making it to the central Aleutians Thursday night. && .LONG TERM FORECAST (Days 3 through 7: Friday through Tuesday)... The entirety of southern mainland Alaska will be under the influence of broad upper level ridging on Friday, which will support sunny skies and very warm temperatures, especially across Southcentral. Near the coast, fog and low stratus will be a concern during the overnight hours. With Southwest Alaska being on the western side of the ridge, the southerly flow and troughing out over the Bering will support more cloud cover, especially for coastal locations. On Saturday, the ridge axis slides eastward over the Copper River Basin, allowing for more cloud cover and cooler temperatures to move into nearly all of Southwest Alaska, while most of Southcentral continues baking with very summer-like temperatures. The exceptions will be Kodiak Island and the coastal areas impacted by clouds and fog. Sunday will be the transition day for Southcentral west of the Talkeetna and Chugach Mountains. The ridge will continue moving eastward into Canada, allowing for wet weather associated with an advancing area of low pressure to move into all of Southwest Alaska, Kodiak, and the southern Kenai Peninsula. For now it looks like most areas from Kenai northward will remain dry, but significant cloud cover should temper afternoon highs as compared with previous days. The Copper Basin will remain very warm. Monday and Tuesday now look to be significantly wetter as compared with previous model runs for much of Southcentral, though rainfall coverage will diminish as one goes eastward. The upper level low responsible for the southerly push causing the wet weather will move into the eastern Bering. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...None. && $$ SYNOPSIS AND MODEL DISCUSSION...RC SOUTHCENTRAL ALASKA...PD SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...JW
Area Forecast Discussion
National Weather Service La Crosse WI
605 PM CDT Tue Jul 17 2018 .SHORT TERM...(This evening through Wednesday) Issued at 313 PM CDT Tue Jul 17 2018 Main forecast concerns in the short-term are on the potential for patchy fog tonight in some river valley locations. Surface high pressure edges east of the region late tonight through Wednesday as a trough approaches from the high plains. The high will provide mainly dry and quiet weather across the area at least through Wednesday. Mostly clear skies and light winds will set the stage for patchy valley fog, mainly in river valleys. Winds increase just above the surface through around 1500 feet tonight which should limit any fog in the main channel of the Mississippi River. The main fog concerns will be along tributary river valleys to the Mississippi River. Clouds will gradually increase across the region from west to east late in the day on Wednesday as the trough edges into eastern South Dakota/Nebraska. .LONG TERM...(Wednesday night through Tuesday) Issued at 313 PM CDT Tue Jul 17 2018 Main forecast concerns are on the potential for heavy rainfall Wednesday night through Thursday. The trough is expected to push into the Upper Mississippi River Valley on Thursday with surface low pressure deepening. Moisture will be pumped northward into the area ahead of this low with precipitable water values increasing to around 1.8 inches with warm cloud depth of 3.5 km. Most of the CAPE will be confined to areas south of Interstate 90, potentially only portions of northeast Iowa and far southwest Wisconsin. This will limit the potential for any stronger storms as far as wind and hail go, with the primary threat being heavier rains. The bulk of the rain should spread from west to east across the area after 12Z Thursday with rain then persisting through much of the day, with scattered embedded thunderstorms. Any storms could produce locally heavy rainfall in addition to the ongoing rains. Some differences noted in the forecast models on the low track, especially with respect to the 12Z NAM, which takes the low southeast into northern Illinois. This is the only model doing this at this time so treating it as an outlier. The ECMWF, GFS, and Canadian take the low into eastern/northeast Wisconsin Thursday night into Friday then stalls. The low then sits over this area into Saturday, and then the big question is how far west will rain showers occur. The showers could continue into Saturday for areas along and east of the Mississippi River. High pressure should then finally build in Saturday night into Sunday, but with the cutoff low in the area, there is the potential for rain showers to linger, especially over central Wisconsin. By the time the rain ends, totals of 1.5 to 2 inches are expected. The widespread cloud cover and rain over the region on Thursday will result in cooler high temperatures in the upper 60s to lower 70s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 605 PM CDT Tue Jul 17 2018 Quiet VFR conditions expected through Wednesday afternoon. An area of high pressure centered over Lake Superior will remain nearly stationary and keep skies clear with light east to southeast winds. Some concern for valley fog overnight with the light winds. Forecast soundings from the 17.21Z RAP would suggest it will be too dry tonight for fog to form as it does not show saturation occurring at the surface. However the 17.18Z NAM forecast soundings would be supportive of valley fog with a visibility reduction at KLSE. For now, will maintain continuity with the previous forecast and not include any fog at KLSE but will monitor trends through the evening for possible inclusion with later forecasts. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Wetenkamp LONG TERM...Wetenkamp AVIATION...04
Area Forecast Discussion
National Weather Service Birmingham AL
717 PM CDT Tue Jul 17 2018 .UPDATE... Evening Update and 00Z Aviation. && .SHORT TERM... Summer time cold front still in central Tennessee with surface dew points even north of the front. It appears that the outflow/prefrontal trough is near the I-20 corridor early this evening. The latest RUC analysis has drier air entrenched over much of Central Alabama, making storm development tough in most places. The best moisture was southeast and west. The main upper trough passes eastward into Wednesday, but some drier air filters into the northern half of the area. Adjusted pops slightly for the overnight hours. With a surface trough, cold front, and several outflows, kept some mention of storms developing at almost anytime. But there will be some decrease in intensity with the loss of daytime heating. 75 Previous short-term discussion:Through Tonight. Low clouds have kept temperatures down and diurnal thunderstorm development at a minimum. The most significant low level boundary appears to be across far north Alabama. Convection along this boundary will likely sink southward this afternoon and evening, and carried highest rain chances across the northern counties. There is also a MCV over Southeast Arkansas tracking towards the southeast. This feature may trigger some development across southwest Alabama later tonight. 58/rose 58/rose .LONG TERM... Wednesday through Monday. Northwest flow will remain in place aloft on Wednesday between a mid-level trough extending from New England southward to the northern Gulf, and a mid-level ridge extending from the Southern Plains westward to the Pacific. A shortwave ridge will also be in place over the Midwest, ahead of a shortwave trough over the Northern Plains. Northerly low-level flow associated with high pressure over the Great Lakes will allow the cool front to sink southward towards the I-85 corridor afternoon. The ECMWF has actually trended towards the other models in showing some drier air mixing down across the northern counties during the afternoon. This will set up a sharp moisture/PoP gradient with scattered to numerous showers/storms across the south and rain-free conditions across the north. Heavy rainfall/localized flooding will remain possible in the high PWAT airmass along/south of I-85/Highway 80. Dew points look to mix down into the 60s over at least some of the northern counties, but temperatures will still hit 90 in most spots. Isolated to scattered showers/storms will remain possible Wednesday night in the far southern counties near the front. Any MCS that develops over the Plains/Ozarks would likely remain well to the west over the ArkLaMiss. On Thursday, the Northern Plains shortwave/upper low will move into MN while a lead shortwave will extend southward towards northwest Alabama. A wave of low pressure more noticeable at 850mb than at the surface will develop in the area of convection along the stalled front along the Gulf Coast. The ECMWF has trended slower with the development of this feature more in line with the other models, and therefore the model consensus now indicates the front will be a bit slower to lift back north as a warm front. This will keep the drier air mass in place longer across the area. PoPs were reduced and may be reduced further in future updates in north-central/interior portions of the area. Best rain chances will be in the far southeast closest to the stalled front. The GFS and ECMWF remain in some disagreement for Friday. The ECMWF is quicker to lift out the wave of low pressure up the East Coast and therefore has more moisture return compared to the GFS. Will go with PoPs in the scattered category areawide. Any storms that do develop Friday afternoon could be strong with 0-6 km bulk shear values of 20-25 kts, dry air aloft, and increasing mid- level lapse rates. Troughing will continue to amplify over the eastern CONUS Friday night into Saturday, as an unseasonably strong vertically stacked low moves into the Great Lakes with a trailing cold front. An area of unseasonably strong northwesterly mid and upper-level flow will be located along its southern flank. Friday night, there will be the potential for one more more MCSs to form along the front. The best upper-level forcing will remain north of the area, but Corfidi vectors would support some activity making it into our northern counties. If an MCS or organized cluster is able to hold together when it arrives Friday night, 0-6 km bulk shear values of 30-35 kts and strengthening mid-level lapse rates would be supportive of the potential for it to be strong to severe. However, confidence in the strength/track of any MCSs this far out is too low to mention in the HWO at this time, especially given the nocturnal timing. The cold front will move into the area on Saturday. Unusually strong (for late July) 0-6 km bulk shear values of 30-40 kts and decent mid-level lapse rates would be supportive of a threat of strong to severe storms assuming sufficient instability. Main wild cards are outflow from the possible MCS Friday night and what impact that could have on destabilization. Some drier air may move in aloft which could limit storm coverage. Given the uncertainty this far out, will not add a severe mention to the HWO to this time, but one could be added in future updates if trends continue. The potential main threat would be damaging winds. A drier air mass looks to move into much of the area Sunday/Monday as the trough remains over the eastern CONUS, resulting in reduced rain chances, dependent on where the front stalls and residual boundary layer moisture. 32/Davis && .AVIATION... 00Z TAF Discussion. Mentioned some convection to start off the period for a few hours this evening, then mentioned only pops south on Wednesday. Believe there will be patchy fog and some low clouds around the area by daybreak, most likely south. Added MVFR vis mention north and low cloud restrictions south. Direr air filters into the region above the surface overnight, but a large inversion sets up trapped moisture below it. Therefore, think there will be enough moisture near saturation to mention these restrictions overnight. How far the drier air axis moves on Wednesday will determine the areas likely to experience showers and thunderstorms. At this time, mention some activity at MGM/TOI by 16z. 75 && .FIRE WEATHER... Above normal coverage of mainly afternoon and early evening showers and thunderstorms is expected again today as a weak front moves towards the area. Highest rain chances will become confined to the southern counties Wednesday and Thursday as the front stalls. Localized fog will be possible each morning where rainfall occurs during the previous afternoon and evening. There are no fire weather concerns. 58/rose && .PRELIMINARY POINT TEMPS/POPS... Gadsden 70 92 67 92 69 / 40 10 0 20 10 Anniston 72 92 69 92 70 / 40 10 0 20 10 Birmingham 74 92 71 92 72 / 40 10 0 20 10 Tuscaloosa 74 94 72 94 73 / 40 20 10 20 10 Calera 73 91 70 92 71 / 40 20 10 20 10 Auburn 73 90 71 90 71 / 40 50 20 30 20 Montgomery 74 92 73 93 73 / 40 60 30 30 10 Troy 74 90 72 92 72 / 40 70 40 50 20 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
854 PM MDT Tue Jul 17 2018 .UPDATE... Issued at 853 PM MDT Tue Jul 17 2018 Reduced PoPs most areas as the best forcing and convection has moved to Washington and Lincoln Counties. The storms are moving southeast and should move out of our CWA or weaken altogether within the next 60-90 minutes. The SVR watch has been cancelled for all of our counties as storm intensity has really waned over the past hour. The HRRR tries to redevelop weak convection over the central mountains east of the Continental Divide later this evening but do not see a obvious (nor subtle for that matter) reason why convection would redevelop there. ESRL/PSD Platteville profiler showing the trough axis has already passed across the I-25 corridor over the last couple hours, and GOES-16 WV and IR trends underwhelming for significant upstream convection. Cannot rule out a stray shower through midnight across the central mountains and Palmer Divide, but feel the subsidence and stabilization should end shower activity area wide around midnight or so. Otherwise the forecast looks on track overnight through Wednesday with no convection expected area-wide and day #34 of 90+ degF max temp at Denver. && .SHORT TERM...(This evening through Wednesday) Issued at 400 PM MDT Tue Jul 17 2018 It`s looking like convection will be a mess through this evening. A preliminary round of convection that started on the foothills convergence zone looks like it will put out an organized wind boundary that will move eastward. This is ahead of the still slower lift from the jet streak which is now over northwestern Colorado. This means the lift will be separated from the good moisture and the developing convergence along the outflow boundary. So, as usual around here, we won`t have one good focus. A possible exception is the storm near Cheyenne which is the best organized and is probably rolling through the greatest instability. This still could drift toward a splitting supercellular structure as it moves into both better instability and a little better low level wind field, though it`s pretty linear now. Mesoscale models have been trending away from the strongly right-turning storm they had earlier, but this storm still looks to be in a favorable position. This leaves Denver and our other big cities in a hole, with surrounding convection, but cooler and cloudy for the most part. Still expecting scattered weaker convection, mainly north and south of Denver, with a second batch coming over this evening tied to the jet. But the severe risk for Denver is looking fairly low, and the risk for more than minor street flooding as well. Drying/clearing/subsidence will move in behind the jet streak overnight, along with a bit more westerly flow. A little bit of drying should result in much less convection, and over and west of the mountains the low level moisture should mix out, almost eliminating convection. There could be an isolated storm around Park county, or near the eastern border late in the day, but the odds are pretty low. Forecast temperatures are a little above guidance, which has been good for our warm dry days. There will be a little breeze in the mountains and low humidities, but not up to Red Flag Criteria, and the recent rain has temporarily lowered the fire danger in most areas anyway. .LONG TERM...(Wednesday night through Tuesday) Issued at 400 PM MDT Tue Jul 17 2018 An upper level ridge centered over the Great Basin will progress to the east bringing subsidence to the forecast area through Thursday. This will continue the hot temperatures. GFS and NAM indicate light QG ascent Thursday evening but there is very little to no moisture present in model soundings so the grids will remain dry. Friday through the weekend there will be an increased chance for late day showers and thunderstorms. Forecast soundings show precipitable water (PW) values will reach 1.00 to 1.32 inches Friday afternoon through the weekend. Monday there will be a slight cool down as the ridge flattens. Chances for showers and storms will continue with high PWs through most of the day. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 853 PM MDT Tue Jul 17 2018 VFR conditions will prevail through Wednesday. The airmass for the rest of this evening is becoming more stable with time. Latest trends in radar/satellite show all showers weakening upstream of the metro area terminals and forcing to the west looks too weak to warrant further shower development. Thus, TAF sites should remain dry the rest of this evening and into the overnight hours. Active gust fronts are all well east of the TAF sites and the strongest outflow boundary from early evening convection is washing out north of KDEN. Can`t rule out an outflow boundary from the convection across far E. Colorado overnight but if one forms we should be able put it in the TAF with lead time. No significant impacts to the terminals or approach/departure gates on Wednesday with no convection expected across central and northeast Colorado. Light north winds around 10 kts are expected tomorrow after 17Z or so, then drainage winds after 03Z or so Wednesday evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Schlatter SHORT TERM...Gimmestad LONG TERM...Sullivan AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Boston/Norton MA
944 PM EDT Tue Jul 17 2018 .SYNOPSIS... Scattered showers and a few left over thunderstorms will come to an end in most locations by midnight...but linger a bit longer across southeast New England. Other than perhaps some lingering showers early Wednesday across Cape Cod and Nantucket, dry weather is anticipated the rest of the work week along with much lower humidity including warm afternoons and cool nights. Unsettled weather may return sometime Sunday into Monday along with increasing humidity. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 10 pm update... Line of widespread light rain with embedded heavier showers, perhaps a rumble of thunder, continues SE ahead of a sweeping cold front expected to push offshore of S New England towards morning. Have toned down on thunder overnight prevailing as isolated. With isolated thunderstorms, a mention of heavy rain. Near-term high res guidance, especially HRRR and HRRR-TLE, is doing a decent job with handling trends. Low clouds, patchy fog likely to be an issue along the S/SE coast towards morning with moist SW flow as nocturnal cooling proceeds. Soupy conditions prevailed, should stay fairly mild overnight with lows around 70. However, scouring dry air NW as noted in observations and within RAP/HRRR models RH fields through the column. Expect improving conditions across the interior overnight. Yet, with partial clearing, falling temperatures, light winds behind the front and antecedent rains, likely to be contending with patchy shallow ground fog for interior locales. Dry air advection will be proceeding which should limit the widespread nature, but wouldn`t be surprised to see lower valley issues per cold air drainage of a very moist airmass immediately above the damp ground. Locally dense in spots, around 1 mile possible. With cold frontal passage, dewpoint discontinuity, likely will see with further progression into the tropical, moist air a brief burst of NW flow. By morning, locations across the S-coast, Cape and Islands may see gusts up around 20 mph with cold frontal passage. && .SHORT TERM /6 AM WEDNESDAY THROUGH 6 AM WEDNESDAY/... Wednesday... A much better day of weather on tap for Wednesday behind the cold front. Perhaps a few lingering showers across the Cape/Islands into mid to late morning. Otherwise...becoming mostly sunny with high temperatures into the 80s in most locations although a bit cooler across portions of the Cape/Islands. Much lower humidity though will make for a much more comfortable day across the entire region. && .LONG TERM /WEDNESDAY THROUGH TUESDAY/... Highlights... * Dry and much less humid later Wed thru Fri, possibly into Sat * Highs 80-85 each afternoon and 50s at night * Showers/storms and humid conditions return Sunday/Monday Overview... 17.00z ensembles (ECENS & GEFS) show northeast trough Wednesday departing and deamplifying which gives way to ridging Friday and likely lingering into Saturday. At the surface this translates to a cold front slowly exiting the Cape Wed followed by 1018 mb high pressure building into New England Wed night/Thu and accompanied by a much less humid airmass. The high then moves offshore Friday but with ridge axis arcing back into New England thru Saturday. Ensembles suggest northern stream remains active with robust mid level trough entering the Great Lakes this weekend and taking on a negative tilt along the eastern seaboard Sun/Mon. This will support a return to more humid weather along with risk of showers/T-storms. Temperatures... 850 mb temps begin Wed around +13C/+14C but then lower to about +11C in the post frontal airmass Thu morning, but modify to +13C by days end, yielding highs in the low 80s away from coastal seabreezes. Airmass slow warms to about +15C Friday and Saturday which will support highs in the mid 80s inland. However humidity remains comfortable as seen by GEFS PWATs remaining below normal (1 to 2 standard deviations below normal) thru Sat with core of dry air over the region Wed night into Thu. This dry airmass will support lows in the 50s overnight, very comfortable. Also given high pres overhead Thu ngt decided to lean toward the cooler MOS guidance per ideal radiational cooling conditions. This dry column will also yield plenty of sunshine Thu and Fri, possibly Sat as well. 850 mb temps remain about +15C Sunday but do warm to about +17C Mon. However the main story Sun/Mon will be the increasing humidity as the low level flow becomes southerly and advects dew pts into the 60s Sunday and then low to mid 70s Monday! Precipitation... Any organized showers/T-storms will be focused across Cape Cod and Nantucket Wed morning as slow moving cold front and frontal wave move across this region in the morning. Trailing short wave sweeps across the region later in the day along with attending cold front moving offshore. Thus drying trend Wed which persist Thu, Fri and likely into Sat. Next chance of showers/T-storms likely arrives Sun and Mon as negative tilt mid level trough dives out of the Great Lakes into the Mid Atlc region. Heavy rainers possible as subtropical stream gets captured by negative tilt trough sending PWATs of +1 to +2 standard deviations up the eastern seaboard into New England Sun/Mon. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tonight/... Tonight...Moderate confidence. Line of widespread -RA with embedded RA/+RA, perhaps a rumble of TSRA. Given isolated nature of TSRA, have removed from terminals. Focused lowest conditions associated with -RA SE of LWM-ORH-HFD with potential IFR-LIFR CIGs and MVFR VSBYs. Expected mixed outcomes S/E with terminals wobbling VFR-IFR. Should see clearing SE towards morning with a sweeping cold front. Lowest conditions pushed towards Cape and Islands. However, across the interior, light winds, recent rains, partial clearing, likely will be dealing with patchy IFR-LIFR shallow ground fog towards morning. Noted 3SM BR roughly 8-11z for higher confidence terminals. With cold frontal passage, could see a brief burst of NW winds around 320 with 10G20KT, pushing offshore around 12z over Cape and Islands. Wednesday...High confidence. Lingering low clouds/fog patches across the Cape/Islands during the morning lift by late morning/early afternoon. Otherwise...VFR conditions. Gusty N winds roughly 15-21z over Cape and Islands with 10-15KT sustained, gusts up to 25 kts. KBOS Terminal... Hold BKN008 for the first couple of hours but should scour out towards midnight then hold VFR with winds turning N. KBDL Terminal... Ground FG possible towards morning. Will hint at the potential 9-11z with 3SM BR for now. Increase if greater confidence is obtained. Outlook /Wednesday through Sunday/... Wednesday Night through Saturday: VFR. Saturday Night: MVFR/IFR conditions possible. Slight chance SHRA. Sunday: Mainly VFR, with areas MVFR possible. Chance SHRA, chance TSRA. Sunday Night: Mainly MVFR, with local VFR possible. Chance SHRA, chance TSRA. Monday: Chance SHRA, chance TSRA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tonight/...High confidence. Tonight... Cold front pushing offshore overnight towards morning. With passage by morning could see a brief uptick in winds out of the NW with sustained values 10-15 kts with gusts up to 25 kts. Otherwise, through the remainder of this evening, SW flow around 10 kts, widespread light rain with embedded heavier showers, perhaps a rumble of thunder. Contributions to low clouds and lower visibility for most of the time. Waves above 5 feet on the outer waters, small craft headlines continue towards midnight. Will evaluate whether extension is necessary with cold frontal passage with later forecasts. Wednesday... Winds and seas should remain below small craft thresholds. Some northeast wind gusts up to 25 knots or so are possible across the Cape/Islands by mid-morning continuing into afternoon, diminishing towards sundown. Outlook /Wednesday through Sunday/... Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Thursday Night through Saturday: Winds less than 25 kt. Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, chance of thunderstorms. Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, chance of thunderstorms. Monday: Winds less than 25 kt. Areas of rough seas. Chance of rain showers, chance of thunderstorms. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ250-254>256. && $$ SYNOPSIS...Frank/Nocera NEAR TERM...Frank/Sipprell SHORT TERM...Frank LONG TERM...Nocera AVIATION...Frank/Nocera/Sipprell MARINE...Frank/Nocera/Sipprell
Area Forecast Discussion
National Weather Service Cheyenne WY
715 PM MDT Tue Jul 17 2018 .UPDATE... Issued at 709 PM MDT Tue Jul 17 2018 Upgraded inherited fire weather watch to a warning for Carbon and Albany Counties for Wednesday. Conditions out there are close to Red Flag conditions now with 700mb winds of 10-15 knots. Forecast for tomorrow showing 700mb winds of 20-25kts, so do expect stronger winds. Confidence very high in this happening given current conditions. Also added extreme southwest Carbon County (FWZ 304). Updates have been sent. As for ongoing Severe Thunderstorm Watch...instability still quite high east of the Laramie Range with surface based Capes around 3000 J/KG on SPC`s Mesoanalysis page. HRRR showing redevelopment of convection over the next couple hours. So will keep the watch going for now. By sunset, we should know what the convection is going to do. && .SHORT TERM...(This evening through Thursday) Issued at 206 PM MDT Tue Jul 17 2018 Convection starting to fire around the Laramie Ranges so far and expect this to continue as activity moves east through this evening. Potential for some severe storms there with the best area looking to be over northern parts of the CWA plains into this evening where better instability and shear is expected. Storms should move a little faster than yesterday but with wet grounds over the Panhandle any heavy rain could produce some flooding so will maintain the watch there for tonight. Convection should taper off/move out later tonight as a shortwave move by the area. Dry and pretty warm conditions will be over the CWA Weds through Thursday under a dry wnw flow atop an upper high centered over the 4 corners area. This will cut off the monsoonal flow for the with the high in that position. Concerns will be more with fire conditions the next two days as the airmass dries. .LONG TERM...(Thursday night through Tuesday) Issued at 206 PM MDT Tue Jul 17 2018 Little change seen for Friday though a minor cool front should nudge temps down a bit as it passes by in association with a weak impulse. Chances for mainly afternoon and evening convection should increase a bit over the weekend into early next week as moisture begins filtering back over the area. An upper low moving east over the Canadian prairies may drive a decent cool front across the CWA towards Monday and help chances for pcpn then. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1141 AM MDT Tue Jul 17 2018 The main concern with this forecast package is the thunderstorm chances again this afternoon and evening. Latest water vapor loop was showing a shortwave tracking through northern Wyoming. This feature was tracking east and should cause some thunderstorms to flare across northern Wyoming this afternoon. There is also enough moisture and upslope flow to trigger some isolated convection along the southern Laramie Range. Therefore, we went ahead and inserted some VCTS in the LAR/CYS TAF sites early this afternoon. Not as confident during the early evening at this point, but we will continue to monitor through the afternoon. Further north in KCDR and KAIA thunderstorm chances are looking fairly good this evening as an area of thunderstorms should blossom northeast Wyoming and track east-southeast towards the KCDR and KAIA taf sites between 04-06z. Meanwhile, KSNY and KBFF may be on the southern edge of this complex of storms. && .FIRE WEATHER... Issued at 206 PM MDT Tue Jul 17 2018 Increased fire weather concerns over the next couple days as drier air moves over the area. Some gusty winds out west both Weds and Thursday afternoon and with dry fuels have opted to post a Fire Weather Watch for tomorrow afternoon/early evening for zones 303 and 308 where at least marginal conditions should occur. Similar setup for Thursday. Otherwise mainly dry and warm weather for the rest of the week then some increase in moisture should allow for an uptick in convection over the weekend. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Red Flag Warning from 11 AM to 8 PM MDT Wednesday for WYZ303-304- 308. NE...Flash Flood Watch until 6 AM MDT Wednesday for NEZ002-003- 019>021-054-055-095-096. && $$ UPDATE...GCC SHORT TERM...RE LONG TERM...RE AVIATION...REC FIRE WEATHER...RE
Area Forecast Discussion
National Weather Service Dodge City KS
1100 PM CDT Tue Jul 17 2018 ...Updated Aviation... .SHORT TERM...(This evening through Wednesday) Issued at 321 PM CDT Tue Jul 17 2018 Outflow boundary from an early morning MCS over western Nebraska into central Kansas had pushed through southwest Kansas by late morning. Satellite imagery shows the boundary continuing to push south through central Oklahoma while western portions of it have become nearly stationary over the Oklahoma Panhandle. Surface winds north of the boundary over far southwest Kansas have veered with time and become light and variable to southerly at 5-15 mph. Visible satellite and radar imagery are indicating some thunderstorms developing along the outflow boundary over the Oklahoma Panhandle where surface moisture convergence has been focused for the past several hours. Model output concerning the timing and areal coverage of convection late this afternoon through tonight is pretty variable which does not make for much confidence in this forecast. Given the way the surface features have lined out this afternoon, it seems that the HRRR has the best handle on the near term storm evolution, especially regarding the OK Panhandle storms. Later this evening and through the overnight hours, the HRRR has been suggesting that clusters of thunderstorms developing off the Colorado Front Range will propagate east into southwest Kansas later this evening into the overnight hours. This seems reasonable given the increasingly unstable airmass developing north of the outflow boundary over far southwest/southern Kansas as indicated by the SPC Mesoanalysis page. A weak upper disturbance showing up in the water vapor imagery over northwest Kansas at this time could aid in sustaining this overnight convection. Have reconfigured late afternoon and overnight precipitation chances to reflect this thinking. Far northeast sections of the forecast area may not see any storms tonight but can`t totally rule them out there either. Thunderstorms will be winding down or moving out of the forecast area by daybreak Wednesday. The exception to this will be the northeast part of the area around Hays. The NAM has also been hinting at another MCS diving out of eastern Wyoming into northern Kansas by Wednesday morning. Current forecast tracks would take it east of the Hays area but will maintain some slight chance pops there in the morning for that. .LONG TERM...(Wednesday night through Tuesday) Issued at 321 PM CDT Tue Jul 17 2018 The extended period will see the upper level ridge building eastward toward the central and southern High Plains. The models continue to show a break in thunderstorm activity across western and central Kansas through the end of the week, along with the possibility of warmer temperatures at least on Thursday and possibly Friday. Disturbances passing by through the northern High Plains could force frontal boundaries down into western Kansas that will keep the very hot temperatures confined to the southern Plains. By early next week the models show the upper level high pressure retrograding back into the western states with northwest flow aloft over the central High Plains. This is a favorable pattern for late evening and overnight convective complexes developing off the eastern slopes of the Rockies and rolling southeast through western Kansas so we could be looking at a return to wetter weather by the middle of next week. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1100 PM CDT Tue Jul 17 2018 As of 04z, a large thunderstorm complex was moving east near P28 and a smaller complex was slowly weakening over eastern Colorado. Outside of a mention of VCSH at GCK, do not see convective impacts at any of the terminals for the next several hours. Some models drag convection eastward over SW KS overnight, others don`t, so kept TSRA out of the TAFs for tonight for now. Consensus of short term models show MVFR (perhaps IFR) stratus developing at HYS/DDC after 09z Wed, with some support from 00z NAM. With the very moist boundary layer and weak upslope components, included this stratus in the DDC/HYS TAFs around 12z/sunrise. Daylight Wednesday, light SE winds and a VFR cumulus field will prevail. Additional scattered convection is expected after 21z Wed, most likely across the NE zones near HYS, and this is where a TEMPO convective group was included. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 94 70 100 / 40 10 10 0 GCK 66 92 67 99 / 30 10 10 0 EHA 69 96 68 101 / 30 10 10 10 LBL 69 97 69 102 / 40 10 10 0 HYS 69 89 69 97 / 30 20 10 10 P28 72 94 72 101 / 60 10 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Gerard LONG TERM...Gerard AVIATION...Turner
Area Forecast Discussion
National Weather Service Wilmington NC
1055 PM EDT Tue Jul 17 2018 .SYNOPSIS... Increased chance of showers and thunderstorms will continue as a cold front moves slowly across the area tonight into Wednesday. The front will dip south of the region on Thursday before shifting back to the north this weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1030 PM Tuesday...Most of the convection has faded away later this evening leaving only some lingering areas of pcp across the forecast area. Main activity back to the west associated with cold front and should move slowly southeast and diminish in intensity leaving mainly chc of lingering lighter pcp overnight with only a slight chc of any stronger convective development possible overnight. Discussion from 300 PM follows... The shortwave trough moved off the coast this morning and is still producing widespread convection off the coast. The latest models show the large scale trough to our north and only a few weak shortwaves embedded in the upper level flow. Currently scattered convection is occurring inland and 16 UTC HRRR is showing coverage increasing after 6 PM and then lingering overnight mainly over southeast North Carolina through sunset. The weak cold front is expected to reach the coast around sunrise Wednesday and then slowly shift just south of the area. The models continue to show the deep moisture over the forecast area through Wednesday and thus will a good chance of showers and thunderstorms for our area on Wednesday. Lows tonight are expected to be around 73 inland to 77 at the beaches, and the highs will reach the mid to upper 80s. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 305 PM Tuesday...The front will continue to drift southward Wednesday night, stalling just south of the forecast area during Thursday and Thursday night. A moisture gradient will become established as a result with high precipitable water values clipping the far southern zones to the waters east of Cape Fear, and the lowest values toward the northern Pee Dee and LBT zones. POPs will follow a similar striation through the short term with the best chances Wednesday night. The continued chance of rain, cloud cover, and surface ridge from the north will keep highs a few degrees below normal during Thursday. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 305 PM Tuesday...Cold front and weak surface wave will be lifting north across the region on Friday. This low level ascent will be bolstered by mid level height falls and vorticity advection and even upper level divergence. These factors in the face of precipitable water values approaching all time high values of 2.4" points to the potential for heavy rainfall. Models are not in agreement with the placement of the front/track of the low and thus where the heaviest rainfall occurs (coastal vs inland). Some of the ECMWF QPF forecasts have been quite impressive and the recent 12Z run has joined the GFS in favoring coastal areas. At some point on Saturday there may be a lull in the heavy rain as the first energy aloft moves offshore but another source of lift will impinge upon the area soon thereafter as the Great Lakes trough reloads. Models show the next slug of rain Saturday night or Sunday. By Monday the deep moisture along the front will be shunted offshore but lingering dynamic-type showers could linger area-wide. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 00Z...Convection will remain active over the southern portion of the CWA through 02Z, then wind down but still isolated overnight. A cold front will drop into the CWA toward morning, but will stall along the coast. Some near IFR conditions are possible especially inland overnight with post frontal stratus. Wednesday, the front still hangs out along the coast with still a decent chance for thunder. The inland terminals will be in a bit more stable air, but still could get a scattered shower. Winds will be northerly by daybreak at the inland terminals, finally becoming northerly in the afternoon along the coast. Extended Outlook...Occasional MVFR to IFR conditions due to scattered to numerous showers and TSTMs Wednesday, Friday, Saturday, and Sunday. && .MARINE... NEAR TERM /THROUGH WEDNESDAY/... As of 1030 PM Tuesday...Will continue with precautionary headlines for sustained up to 20 knot southwest winds and up to 4 to 5 foot seas across the coastal waters. These elevated winds and seas shoudl linger only for a few more hours. Discussion from 300 PM follows... Southwest to west winds of 15 to 20 knots will continue ahead of a weak front that should drift along the coast early Wednesday. As the front slows the pressure gradient will weaken and the winds will weaken to 10 to 15 knots of Wednesday. Seas are expected to build to 3 to 5 feet and then drop slightly by late Wednesday. Conditions are expected to remain just below small craft advisory. SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 305 PM Tuesday...Southwest winds early Wednesday evening will shift to a northeasterly direction with a very slow frontal passage during the early morning hours Thursday. High pressure over the northeast U.S. will ridge southward across the Carolinas during Thursday with the front just offshore. This pattern will maintain northeast-east flow during the day with speeds potentially in the 15-20 knot range. The old boundary may begin drifting back to the north late in the period, but for the majority of the adjacent coastal water the flow will remain out of the northeast-east. Seas will build in the post-frontal regime during Thursday. The fetch will not allow sea to drop significantly until late in the period. Potential for scattered to showers/tstms each part of the forecast given the proximity of the front. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 305 PM Tuesday...Front will return northward back into the area on Friday with a weak wave of low pressure moving along it. Wind turns southerly with only a minor increase in speed-the stronger gradient remaining offshore. Broad cyclonic flow develops across most of the eastern U.S. by Saturday yielding a category of wind speed increase Saturday into Sunday. As this flow persists a few advisory-worthy 6 ft seas could develop. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Beach Hazards Statement until 8 PM EDT this evening for SCZ054- 056. NC...Beach Hazards Statement until 8 PM EDT this evening for NCZ106- 108. MARINE...None. && $$ SYNOPSIS...III NEAR TERM...TRA/DRH SHORT TERM...III LONG TERM...MBB AVIATION...43
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
838 PM CDT Tue Jul 17 2018 .SYNOPSIS... Issued at 310 PM CDT Tue Jul 17 2018 H5 analysis from this morning Had a broad trough of low pressure extending form northwestern Quebec-south into West Virginia. Ht. falls of 50 to 60 Meters extended from northern Michigan into srn Quebec this mroning. Further west, northwesterly flow extended into the northern Rockies of the CONUS and Canadian Rockies. West of this flow, a strong shortwave trough of low pressure was centered over central Idahao/far swrn Montana this morning. South of this feature, high pressure was anchored over southern Nevada, central Texas and the western Caribbean. WV imagery as of midday had the Idaho shortwave slightly farther east into Western Montana with a secondary shortwave noted in northwestern Wyoming. At the surface, a stationary front extended from southeastern Montana into northern Iowa. Low pressure was noted over sern Montana with a sutrace trough extending south into central Wyoming. Across western and north central Nebraska this afternoon, skiws were partly cloudy and readings as of 3 PM CDT ranged from 81 at Imperial to 85 at North Platte. && .UPDATE... Issued at 838 PM CDT Tue Jul 17 2018 A new forecast is in place using the RAP and HRRR plus time lagging. The models are backing off on the thunderstorm coverage; probably because of increasing nocturnal stability. The new forecast focuses the best rain changes across ncntl Nebraska which would appear to be consistent with lack of thunderstorm coverage across the Panhandle. UPDATE Issued at 616 PM CDT Tue Jul 17 2018 A forecast update is in place which carries the thunderstorms across Northeast WY southeast through wrn and ncntl Nebraska overnight. The forecast uses a blend of the HRRR, HREF and RAP plus time lagging. This might be too aggressive as the RAP dives a MCS mostly west of highway 83 and while the HRRR carries it right over North Platte. HREF splits the system and weakens its as it approaches highway 83 toward sunrise. The westward moving plume of low level moisture located near highway 83 on radar adds some uncertainty to the forecast as the models don`t seem to capture this. The RAP does show a 20-30kt low level jet developing tonight and this should fuel the forecast for likely thunderstorm development. If the storms across WY move south of the Black Hills in a few hours then the forecast sould verify. && .SHORT TERM...(This evening through Wednesday) Issued at 310 PM CDT Tue Jul 17 2018 Precipitation chances continue to be the main forecast challenge in the near periods. A strong shortwave, currently over southwestern Montana/northwestern Wyoming will initiate convection across the Bighorn Mountains mid afternoon. As this activity moves east into the northern panhandle, the models congeal it into a MCS this evening. As to where the MCS tracks overnight is somewhere up in the air with this mornings model runs. The GFS is the outlier at this time, lifting convection due east overnight. Other model solutions including, the Canadian, WARW, and NAM 12 solutions lift this convetion southeast into the northwestern forecast area, then central and southern forecast area late tonight. The prescence of a decent low level jet and enhanced moisture axis, extending from swrn into northwestern portions of the forecast area tonight. That being said, am favoring the latter model solution which forces convection se across the forecast area overnight. PWATS once again will be above 1.5 inches in my west, which will facilitate a heavy rain threat tonight. In addition, wouldn`t be surprised if we see some strong wind gusts as the complex pushes southeast. With this in mind, and given portions of Sheridan county which are prone to flooding saw some heavy rain last night, am going to hoist a flash flood watch for Sheridan county tonight. South southeast of Sheridan county, a swath of decent rainfall fell across the western sandhills and far swrn Nebraska overnight. In these areas, the main concern for flash flooding would be in swrn Nebraska. Given the latest model forecasts track the heaviest rainfall east of this axis of heavy rain from last night, am not as concerned about a flash flood watch attm. The convective complex will push into south central Nebraska overnight with a lingering threat for thunderstorms in the east and sern forecast area Wednesday morning. The shortwave trough will track across South Dakota and northern Nebraska on Wednesday. There will be a lingering threat for thunderstorms, mainly east of highway 83. .LONG TERM...(Wednesday night through Tuesday) Issued at 310 PM CDT Tue Jul 17 2018 Wednesday night through Friday...The upper level trough will slowly track into eastern South Dakota Wednesday night with the trough axis aligned with the Missouri River Thursday morning. There will be a lingering threat for thunderstorms Wednesday evneing, before convection pushes east of the area. The upper level low will lift slowly east Thursday into central Minnesota then Wisconsin on Friday. Subsidence behind the exiting trough and drier air will push into the region with dry conditions expected. Temperatures will remain seasonal with readings in the 90s for Thursday, followed by upper 80s for Friday. Friday night through Tuesday...Ridging will amplify across the central and northern Plains Friday night into Saturday with dry conditions continuing. On Saturday night, the ridging will break down thanks to a strong shortwave approaching the northern Rockies. Mid level warm air advection will increase as the ridging breaks down. This will lead to a chance for thunderstorms Saturday night into Sunday. Another round of thunderstorms are possible Sunday night into Monday as a cold front is forced through the forecast area. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 616 PM CDT Tue Jul 17 2018 The thunderstorms across WY are expected to move southeast, into and through wrn and ncntl Nebraska tonight. Scattered to numerous thunderstorm coverage is expected unti 15z Wednesday. Isolated thunderstorm coverage is expected along and east of highway 83 15z-21z Wednesday. Scattered thunderstorm coverage is expected east of highway 83 21z-00z Wednesday afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until 6 AM MDT Wednesday for NEZ004. && $$ UPDATE...CDC SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
700 PM EDT Tue Jul 17 2018 .SHORT TERM...(This evening through Wednesday) Issued at 411 PM EDT TUE JUL 17 2018 WV imagery and RAP analysis indicated a mid/upper level trough from nrn Quebec into the ern CONUS and a ridge from the nrn plains into Saskatchewan resulting in nw flow through the wrn Great Lakes. At the surface, high pressure was building into Lake Superior and Upper michigan bringing diminishing winds and clearing skies with mainly just few/sct inland cu. Seasonably cool dry air has also spread across the area with temps from the low and mid 60s north to the the lower 70s south and dewpoints around 50. Tonight, favorable radiational cooling conditions with light winds, clear skies and PWAT values at or below 0.5 inch will allow temps to drop to the lower end of guidance with mins into the lower 40s inland, with a few upper 30s possible in typical cold spots. Wednesday, Another day with light winds and mostly sunny skies as the sfc high builds slowly to the southeast of the area will allow prominent lake breezes to develop. Expect highs to range from around 70 near the Great Lakes to near 80 inland. .LONG TERM...(Wednesday night through Tuesday) Issued at 411 PM EDT TUE JUL 17 2018 Models suggest that a developing cutoff low moving from the Upper MS valley into the western Great Lakes will dominate the weather late this week into the weekend. Another low will approach the area, moving into Manitoba early next week. This will keep high temps at or below normal with wet/unsettled weather. Wednesday night into Thursday, As the high slowly moves away to the east, increasing southerly winds and WAA will bring temps back to around 80 with the coolest conditions along Lake Michigan. Clouds will also thicken over the west by Thu afternoon as the mid level and sfc low move into MN. Friday through Sunday, The models continue to show some differences in handling the evolution of the low with the ECMWF now remaining farther north with the track compared to the GFS/GEFS. Regardless of the eventual track, sct/nmrs showers are expected to develop from sw to ne Friday and continue through Saturday before slowly diminshing from the west Saturday night into Sunday morning. The greatest instability and tsra chances are expected Fri afternoon into Fri evening with modest MUAPE values in the 500-1000 J/Kg range possible. Only isold tsra may be possible over the east by Saturday as more stable air with nrly low level flow moves in by Saturday evening. Mon-Tue, confidence is low with the timing of rain chances early next week as the ECMWF is faster with the progress of the mid level low and shortwave trough moving into the region Monday compared to the GFS/GEM which maintain sfc riding over the area before pcpn chances finally move in Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 700 PM EDT TUE JUL 17 2018 VFR conditions will prevail through the forecast period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 411 PM EDT TUE JUL 17 2018 High pressure will continue to build across Lake Superior tonight bringing diminishing winds. The high pressure will slowly slide off to the southeast Wednesday/Thursday. South to southeast winds will increase again late Thu into Fri to possibly as high as 25 knots over eastern Lake Superior ahead of an approaching low pressure system over the Plains. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...JLB AVIATION...07 MARINE...JLB
Area Forecast Discussion
National Weather Service Blacksburg VA
1046 PM EDT Tue Jul 17 2018 .SYNOPSIS... A cold front will travel east to the coast by Wednesday morning. High pressure follows with drier and somewhat cooler weather into the end of the week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1040 PM EDT Tuesday... Still some lingering showers in the piedmont east of Lynchburg as well as across the NC foothills/mountains ahead of the cold front. Mesoanalysis shows deeper moisture convergence in these areas as well. Drier air starting to work into the WV mountains, and will take all night to edge to the Blue Ridge. Should still see showers diminish across the area by 1-2am, with fog mainly in the mountains. Previous discussion from early evening... Best instability and storm coverage has exited the piedmont with just a few showers/storms across the mountains in a secondary axis of higher instability ahead of the front. High-res solution still painting a threat of showers in a scattered nature early this evening before things dry out, mainly in the NC portion of the forecast area. Otherwise, still some delay in drier air late will provide opportunity for fog formation overnight, especially in the mountains. No other major changes to the forecast from earlier. Previous discussion from early this afternoon... A cold front in the mountains this afternoon will move east tonight into Wednesday. Scattered to numerous showers and thunderstorms are expected ahead and along the cold front. A pre-frontal trough across the piedmont and southside trigger convection aided by a weak upper shortwave. SPC Mesoscale analysis at 18z showed CAPEs 2 to 3k j/kg and Lis from minus 1 to minus 3. Isolated severe thunderstorms may be possible this afternoon with gusty winds and hail as main threat. With high PWATs from 1.5 to 2.0 inches, some of the storms will contain heavy rains. Hiresw-ARW-EAST, HRRR and NAMnest showed a couple of clusters or bands moving east across the forecast area. The GFS and ECMWF also have showers and thunderstorms moving across the area this afternoon into tonight. The convection should diminish with the loss of solar heating tonight. The frontal boundary should push out of the region overnight allowing the flow to turn northwest with decent cool advection developing northwest half late as the upper trough passes across the region. Areas of fog will develop overnight into Wednesday morning. Low temperatures will range from the mid 50s in the northwest mountains to around 70 degrees in the piedmont. High pressure will build southeast out of the Ohio Valley on Wednesday in our region. High temperatures Wednesday will vary from the lower 70s in the mountains to the mid 80s in the piedmont. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 310 PM EDT Tuesday... High pressure over New England will wedge south into the Carolinas Wednesday night and linger into Friday morning. Most of the forecast area will remain dry with the exception of the Mountain Empire of West Virginia to the High Country of North Carolina where the wedge will erode and an inverted surface trough stretches north from the Tennessee Valley to the southern Ohio Valley Thursday. Coverage of convective will be isolated. Any afternoon showers will fade during the evening. Dry cooler air will bring a dramatic drop in humidities Wednesday night into Thursday night as dew points fall into the lower 50s. Overnight lows will also trend cooler with 50s across the mountains to lower 60s east. With dry air and abundant sunshine in the afternoon, Thursday`s highs will range in the 80s with mid 70s along ridgetops. The wedge will hang around through Friday, but will erode from the west and southeast. An upper level trough is expected to become a close low over the Great Lakes on Friday. This low will send short waves into the Ohio Valley and erode the wedge from the west. Across the Southeastern states, a tropical disturbance is expected to track along the wedge boundary, then off the North Carolina coast Friday night. As this disturbance advances north, it will erode the wedge from the southeast. As the wedge erodes, the chances for showers and thunderstorms will increase, especially across the mountains Friday afternoon into the evening. Temperatures and humidity will also be on the increase Friday with highs in the upper 70s to lower 80s west of the Blue Ridge to the mid to upper 80s east. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 245 PM EDT Tuesday... On Saturday, the closed low expands into the Deep South and covers most of the US from the Mississippi Valley eastward. In the afternoon, there is a negative tilt to the trough in the eastern US that could bring active weather to the region. A weak cold front will then slide across the region Saturday night. Sunday, moreso Monday and Tuesday, could be active days with heating occuring under the cold pool as the closed low may dive south over the area. The area will remain under a trough through most of next week as a strong blocking ridge drifts westward in the Western Atlantic. Afternoon and evening showers and thunderstorms are likely each day from this weekend into the following week. Temperatures will run cooler than normal through the period. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... As of 713 PM EDT Tuesday... A cold front in the mountains will move east tonight. Most convection will be away from the terminals though could see a few showers still near enough to Danville to keep in the TAFS for now around 01-02z. Drier air will arrive Wed morning, so with some residual humidity and wet ground with clearing skies, fog will be likely in the mountains. KLWB is the taf site with the best chance for IFR/LIFR fog, with MVFR to IFR at times at BLF/BCB. High pressure building in from the north should bring widespread VFR under drier air for Wednesday. Medium confidence in ceilings, visibilities and winds during the taf period. Extended Aviation... Return flow looks to transport moisture back into the area Thursday and Friday but still looking at mainly VFR. Scattered showers and thunderstorms with sub- VFR conditions are expected Saturday ahead of the next cold front. Scattered showers and thunderstorms are likely on Sunday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...KK/WP SHORT TERM...RCS LONG TERM...RCS AVIATION...JH/KK/WP
Area Forecast Discussion
National Weather Service Tucson AZ
905 PM MST Tue Jul 17 2018 .SYNOPSIS...Plenty of moisture and instability will remain in place to support daily showers and thunderstorms through at least the middle of the week. Partial drying from the east may lead to reduced thunderstorm coverage by the weekend, along with hotter temperatures. && .DISCUSSION...Thunderstorms continue this evening mainly SW of Tucson where greatest instability resides, but a couple of storms even occurring over the Rim at this hour. 00z sounding showed increased easterly mid level flow which is aiding in storm intensities, increasing storm movement and providing increased potential for strong wind gusts. HRRR has been verifying well since late this afternoon and continues to show that thunderstorms will continue to move across primarily western and central Pima County into the overnight hours. Cannot completely rule out a stray shower or storm in the Tucson Metro eastward through at least midnight. Will keep the 10 percent chances there as in the going forecast. && .AVIATION...Valid through 19/06Z. Isolated to scattered SHRA/TSRA mainly west of KTUS and near the International Border through the night. The Wednesday morning hours should be dry but at least ISOLD TSRA coverage is expected again after 18/19z. Cloud bases 8k-12k ft AGL with SCT- BKN clouds above 20k. Winds remain below 12 kts through the period, with stronger gusts possible around TSRA. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...A shift in the weather pattern will begin to take place, bringing in drier air and reducing rain chances. However, isolated storms could still develop, especially over the higher terrain. Temperatures also gradually warm through the week. 20-ft winds remain below 15 mph, although the Upper Gila River Valley will experience gustier northwesterly winds at times. && .PREV DISCUSSION...The upper low moving through Sonora, Mexico along with the northern extent of the inverted trough passing through Arizona was showing up nicely in Satellite water vapor imagery. Showers and a few thunderstorms were developing this afternoon in the vicinity of this upper low and across far western Pima county. This general area will be the main focus of showers and thunderstorm this evening and tonight. Cannot rule out a few thunderstorms farther north though. Otherwise, high pressure aloft will become established over the Great Basin region around Wednesday before shifting over the Desert Southwest this coming weekend. This adjustment in the position of the upper high will result in some warming and drying aloft by the end of the week. This warmer and drying will eventually translate to less thunderstorm activity and hotter daytime temperatures by the weekend. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at
Area Forecast Discussion
National Weather Service Las Vegas NV
700 PM PDT Tue Jul 17 2018 .SYNOPSIS...Hot and humid conditions will continue through mid week with thunderstorms possible across much of the forecast area through the end of the week, especially in the higher terrain. && .UPDATE...At 7 pm...scattered thunderstorms were primarily confined to parts of Lincoln County and northern Mohave County with a couple of weak cells in western Clark County. The activity in Lincoln County is expected to drift to the southeast into the northeast portion of Clark County over the next few hours. In general, there should be a downward trend in most of this activity after sunset. Updates are out. -Salmen- && .PREVIOUS DISCUSSION...231 PM PDT... .SHORT TERM...through Thursday night. Two primary weather features influencing our weather are high pressure currently centered over the central California coastline and an inverted trough moving across southern Arizona and northern Mexico. Overnight, the high pressure center moves inland over central California and the inverted trough pushes into southern California. Any storms that survive or develop overnight, will generally move to the southwest across Mohave County and southern San Bernardino County. The last several runs of the HRRR has trended away from bringing storms out of Lincoln County into Clark County. Left a chance of showers/storms in the Spring Mountains and Sheep Range this evening but kept the Las Vegas Valley dry based on the latest HRRR forecast. On Wednesday, high pressure shifts east into central Nevada while the inverted trough lifts northwest across San Bernardino County. This track will bring higher moisture and increasing instability across the Sierra and Inyo County. More than sufficient moisture and weak instability elsewhere will give most areas a chance of showers and storms Wednesday afternoon/evening with the possible exception of San Bernardino County which will lie in an unfavorable region of downward motion behind the trough. The high is forecast to re-position over the four corners area on Thursday with a general southeasterly flow setting up across the forecast area. Any embedded disturbances or decaying MCS that form south-southeast of our area Wednesday night could become a player influencing convective activity Thursday. An Excessive Heat Warning is in effect through Wednesday evening for the Owens Valley and Esmeralda County with a Excessive Heat Advisory in effect for the White Mountains of Inyo County. Hot and humid conditions are expected with sky conditions and temperatures greatly influenced by the amount of clouds spread across the region from decaying overnight convection. .LONG TERM...Friday through Tuesday. By FRI, an upper level trough over NW Canada and the NW Pacific will help nudge the ridge overhead eastward, eventually moving it over New Mexico and Texas by Saturday. The eastward propagation of the high should result in some mid-level dry air off the SoCal coast to filter in across southwestern portions of our CWA FRI-SAT. However, lingering low level moisture combined with daytime heating will still allow for thunderstorms to develop mainly along higher terrain through the weekend. By SUN-MON, models are now shifting the high pressure back across the southwest and over Arizona. This westward propagation will increase temps and continue to keep thunderstorms chances mainly focused over the higher terrain through TUE. Main threats with any thunderstorm development will be localized flooding, small hail, and strong to severe outflows capable of producing damaging winds and blowing dust. Besides storm chances, expect light winds less than 10-15 mph, temperatures to increase a degree or two each day and partly sunny to partly cloudy skies. && .AVIATION...For McCarran...Outside of convective influence, light, variable winds below 10 knots will continue across the terminal through the afternoon, favoring an easterly direction. Probability of outflow affecting the terminal this evening is low. CIGs should remain above 10k feet. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered to isolated thunderstorms across the region through the remainder of the afteroon with storms likely to persist through the night along and south of Interstate 40 through southern California and southwest Arizona. Outside of thunderstorm influences, winds will follow diurnal trends with speeds of 5-15 knots. CIGs at or above 10k feet in general but CIGs may drop to 5-7 k feet in shower and storms. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM/AVIATION...Salmen LONG TERM.............Kryston For more forecast information...see us on our webpage: or follow us on Facebook and Twitter