Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/22/16


Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
552 PM MDT WED SEP 21 2016 .AVIATION... 00Z TAF CYCLE Showers and thunderstorms are smattered across northern and central NM early this evening and are rapidly moving northeastward. Some storms thru the eve may produce wind gusts to 40-45kts. Storms across the plains should diminish with sunset, though across central NM, storms may linger to 06Z or thereabouts. Some areas of MVFR cigs are possible overnight, particularly across far NW NM toward sunrise, but not too confident it will occur. Another round of storms will develop on Thursday favoring areas btw the ContDvd and the east slopes of the Central Mtn Chain. Additionally, breezy to locally windy conditions will develop by early afternoon. Wind gusts between 25 and 30kts will be common through early eve. 34 && .PREV DISCUSSION...319 PM MDT WED SEP 21 2016... .SYNOPSIS... Scattered showers and thunderstorms will move northeast across New Mexico through Friday. Some of the stronger storms may produce brief strong wind gusts and perhaps some small hail. Temperatures will be above normal in many areas through Friday before a strong cold front surges through the state by late in the day. Low temperatures will be the coldest since last spring for much of the state. Lows will range from the 20s and 30s across the northern and western high terrain to the 40s and 50s across the eastern plains. Temperatures will likely stay cooler through early next week with a chance for some showers across the eastern half of the state. && .DISCUSSION... The remnant upper level wave from what was formerly Hurricane Paine is shifting quickly northeast across NM this afternoon. It`s low level center dissipated off the northern Baja and any moisture that was associated with it has been washed out across a vast area of the southwest CONUS. Enough forcing is present aloft to combine with afternoon heating for a decent crop of storms around the central and western high terrain. Activity is cruising along and has potential to tap stronger winds aloft. Strong outflow winds and perhaps some small hail are possible with any of the stronger storms. The latest HRRR and SPC SSEO merges convection into an area over the San Juan Mts and the RGV this evening. Thursday is expected to be a repeat of today with perhaps a better focus along and west of the Cont Dvd. Friday will be a dynamic day across NM as a potent Pacific cold front surges southeast through the area. High temperatures will still be quite warm ahead of the front. Veering wind profiles and abundant moisture still in place over the region should allow for at least a thin line of storms along the main frontal forcing. 12Z guidance is still paltry with precip development and has actually trended drier than previous runs. Will maintain chance POPs for now. 700mb temps fall from near +14C to around +4C behind the front. This strong cold advection along with impressive dry air advection will lead into the coldest night since last spring for much of the state. Folks around Farmington will want to keep a close eye on the min temp forecast as we are currently advertising 35F. Sheltered areas that are typically colder may see their first freeze. Overall Saturday appears to be a tranquil day with cool northwest flow over the state. Max temps will be 10 to 20F colder than Friday. The upper level trough is now shown by most of the 12Z guidance to push slowly east away from the area while developing into a large scale upper low over the Great Plains. This is yet another change in the outlook so confidence remains low. Nonetheless, temps will stay cooler through early next week with the greatest potential for any precip over the east. Guyer && .FIRE WEATHER... Moisture levels surface and aloft considerably higher today than on Tue thanks in large part to moisture shunted northeast from the remnants of once Hurricane Paine. Enough sunshine has materialized to generate some spotty showers and thunderstorms across roughly the nw half of the fcst area. More isolated activity struggling to keep going just east and ne of the Sacramento mtns. Majority of the storms should be able to manage wetting rainfall. On Thu this moisture will begin to yield a bit to a drier sw flow out ahead of a deepening trough aloft moving into the Great Basin. Winds through a deep atmospheric layer over NM will be picking up as the upper trough and associated Pacific cold front approach. Lee side surface troughing across the east Thu will encourage development of breezy to locally windy conditions most areas by aftn. Despite some modest drying in the atmosphere Thu there will still be a decent chance of a few showers and storms mainly to the west of the eastern plains thanks to the dynamic forcing of the approaching trough. The main Pacific front should push into and through NM between late Thu night and Fri but moisture will be less Fri than Thu so fewer wetting showers and storms are expected, especially east of the Continental Divide. High temps behind the front across nw and west central NM will be a few to around 10 degrees below seasonal normals. With passage of a pretty healthy back door front Sat night and Sun daytime temps will be below normal pretty much all across the area. Chances for wetting rain later in the weekend and early next week still look to be less than what appeared would be the case a day or two ago, though eastern areas still have a pretty good chance. a developing closed low over to just west of the state looks a little less likely now than was the case over 24 hours ago. In fact by mid to late week next week daytime temps may head back well above normal. The Canadian fcst model though is still holding to a somewhat weaker upper low or deep trough hanging out over the state so dry and warmer for this time period not certain yet by any means. 43 && .ABQ WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service La Crosse WI
645 PM CDT Wed Sep 21 2016 .SHORT TERM...(This evening through Friday) Issued at 358 PM CDT Wed Sep 21 2016 Rain...rain...go away! Unfortunately that doesn`t seem very likely as we wrap up the work week, with the main forecast concern being timing, placement, and amounts of additional heavy rainfall...not to mention the potential for severe storms into this evening. Midday analysis places a warm front just touching our far southwestern CWA, slowly bowing northward courtesy of diurnal mixing, with dew points making a sizable jump toward the lower 70s west of the Mississippi River. In the presence of quite steep low/mid level lapse rates, that added moisture has led to CAPE values surging into the 3000+ J/kg range, with all focus for the next couple of hours on the potential for severe storms. Overall deep shear isn`t terribly impressive, but 0-1/0-2km shear is rather impressive in the 30-40 knot range, with good turning right along the warm front. Given lower LCL heights and said shear, can`t at all rule out a few tornadoes developing the next few hours, in addition to the potential for some pretty large hail given normalized CAPE values of around 0.4...indicative of some impressive instability. Could see individual storms merge into more of a cluster with time with perhaps an increasing wind threat. Not to be forgotten, the even larger issue in the longer term remains heavy rain potential into tonight and perhaps much of Thursday as well. Approach of our next ripple in the flow and associated even deeper surge of tropical moisture from the remnants of Paine should work in tandem with another nocturnal increase in low level jet forcing/moisture transport to deliver another expanding axis of convection somewhere across the area. That "somewhere" may ultimately be just a touch farther north than seen last night as the better mass convergence focuses initially along/north of I-94, but with hints among recent runs of CAM guidance that we will see another southward drift with time - in line with Corfidi vector propagation. Given PWAT values near the top of the chart for late September and the tropical tap/strong elevated instability/3-4km warm cloud depths, don`t have any reason why storms won`t produce another 2-3 inches where they persist, with localized amounts again up to 5 inches as noted with last night`s convection. Of course, exact placement is all but impossible to nail down even at this hour, but suffice it to say flash flooding concerns remain high, especially with many areas primed last night with heavy rains. Beyond tomorrow morning, don`t have the best feeling how things will play out, but with the warm frontal boundary still draped nearby and persistent lift/instability near that feature, can`t at all rule out periods of showers and storms hanging tight through Thursday night and even into Friday. Should see southern areas increasingly become capped with time into Friday as upper troughing digging through the Rockies builds sharp ridging aloft across the Mississippi valley. .LONG TERM...(Friday Night through Wednesday) Issued at 358 PM CDT Wed Sep 21 2016 Looking like the active weather pattern will continue into early next week, with quite the upper trough (very fall-like) progged by the majority of medium range guidance to work east through the Plains into Saturday. Modest height falls, upper divergence, and enhanced jet help should ignite yet another axis of showers and likely some thunder across much of the region into Saturday night, with some potential for severe storms pending timing given increased shear aloft. There remains some question about how fast this system will progress, with the ECMWF steadfast in its idea of a much slower progression as more energy rounds the trough base and works a frontal wave through the area toward Tuesday or Wednesday. The GFS meanwhile also remains steadfast with its faster solution and a much farther north closing off of an upper level low into early next week. At this point, don`t have any reason to go one way or the other but the overall idea is still for continued rain chances at various times, with perhaps a trend toward much cooler conditions toward midweek. Will have to watch this pattern closely as the last thing we need here is additional heavy rainfall (or any rain for that matter), and the potential is there for another bout of widespread heavier precipitation into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 645 PM CDT Wed Sep 21 2016 Convection continues to expand north of the warm front over northern Iowa. The latest run of the HRRR lifts this northeast and into KRST early this evening with MVFR conditions possible. More activity expected to develop along the nearly stationary cold front that extends from southwest Minnesota into northern Wisconsin as the low level jet impinges on it. This should bring a line of storms south into both airports overnight with IFR/MVFR conditions expected. Once this line moves by, some suggestion by the hi-res meso scale models that the rest of Thursday could then be dry. For now will go with VFR conditions behind the line of storms with VCSH in the event it does not end up being all that clean. && .HYDROLOGY... Issued at 358 PM CDT Wed Sep 21 2016 Plenty of water yet to come per our current forecast, with flash flooding concerns first and foremost the main concern overnight. Many spots along and either side of the Mississippi picked up a solid 2-4 inches overnight with some flash flooding/mud slides noted. Additional forecast rainfall of 2-3 inches with localized much higher amounts under any training storms should have little trouble producing additional flash flood concerns tonight, though the exact location of heaviest rain does remain somewhat in question. Looking longer term, river flooding on most if not all river systems will become a bigger issue the next few days, with hints that we may well see another bout of heavy rain later Saturday into Sunday. We definitely don`t need that, but given the setup, don`t be shocked to see upward trends on river forecasts over the next couple of days. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Flash Flood Watch through Thursday evening for WIZ017-029- 032>034-041>044-053>055-061. MN...Flash Flood Watch through Thursday evening for MNZ079-086>088- 094>096. IA...Flash Flood Watch through Thursday evening for IAZ008>011-018- 019-029-030. && $$ SHORT TERM...Lawrence LONG TERM...Lawrence AVIATION...04 HYDROLOGY...Lawrence
Area Forecast Discussion
National Weather Service Cleveland OH
919 PM EDT WED SEP 21 2016 .SYNOPSIS... High pressure will remain in control of the weather across the region into Thursday. A cold front will move into the Great Lakes on Friday then sag south of the area by Friday night. A cooler Canadian high pressure will arrive Saturday into Sunday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... High pressure located over the central SOuthern Tier of NY will remain strong enough to keep the showers and thunderstorms well west of the County Warning Area through the night. Only minor changes to cloud cover and hourly temperatures were made to reflect current trends. Previous Discussion... A few clouds around this evening...primarily across northern OH and nw PA. Some of this is afternoon cumulus which will fade quickly late this afternoon. The mid/high clouds emanated from a decaying MCS across MI this morning. They should drift across the lake this evening. Although it cannot be ruled out entirely...current satellite trends do not look favorable for shower/ts development across southeast MI...so Toledo and across the lake should stay dry. HRRR only guidance showing development early this evening. Otherwise another quiet night with high pressure overhead. Temperatures will be running above normal tonight...but still a number of inland locations will get into the 50s. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/... Pattern begins to amplify for the remainder of the week. While an upper low takes up the Rockies/West Coast and ridge will build across the Mississippi Valley. Precipitation Thursday will remain north of the area along stalled frontal boundary across the Great Lakes. This will provide yet another day with temperatures well above normal. For reference...normals have now dropped into the lower 70s. A shortwave across central Canada will carve a trough across New England and bring the Great Lakes front southward. This front has the cooler weather bottled up to its north...so with its passage Friday temperatures will be brought back closer to normal going into the weekend. We will still likely reach and top 80 degrees Friday. Saturday all will be in the 70s with some upper 60s likely for highs across nw PA and a north-northeast flow. Little has changed with the outlook for precipitation with this front. Moisture and lift limited. Will continue with silent 20 percent chances Friday into Saturday. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... A rather substantial shift in the long range models is noted over the last 24 hours with a trend towards an upper level low closing off over the plains states. This blocking pattern would support a high amplitude ridge building back into the Great Lakes Region with temperatures trending warmer through the extended. Models had shown this blocking pattern last weekend and feel the shift back to it is supported by the strong upper jet over the North Pacific. With that said, started trending the forecast drier and warmer during the early part of next week. This pattern shift will need to continue to be monitored on later model cycles. && .AVIATION /00Z Thursday THROUGH Monday/... VFR conditions with only cirrus will continue through the overnight. Expect patchy mvfr br toward daybreak. OUTLOOK...Some MVFR possible Saturday night in scattered shra/tsra. && .MARINE... A ridge over the eastern Great Lakes will shift south and weaken through the end of the week. A weak area of low pressure will pass north of Lake Erie on Thursday with a weak cold front settling south across the lake on Friday. Northeast winds of 10-20 knots will develop behind the front Friday afternoon and night causing waves to build to 2 to 4 feet into Saturday morning. High pressure will strengthen over the eastern Great Lakes over the weekend maintaining easterly winds on the lake. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Oudeman NEAR TERM...Mullen/Oudeman SHORT TERM...Oudeman LONG TERM...KEC AVIATION...DJB MARINE...KEC
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
640 PM CDT Wed Sep 21 2016 .SHORT TERM.../This evening through Thursday/ Issued at 344 PM CDT Wed Sep 21 2016 The primary concern into tonight is obviously convective trends include heavy rain and severe potential. The current Grinnell-Forest City outflow boundary from morning convection continues to try and initiate new convection but is having little luck sustaining anything or anchoring to it. A detailed look at the cells and radar fineline notes development on either side of the boundary suggesting this is mainly elevated. Thus even though uncapped 3000 j/kg MLCapes are in place just west of the feature there seems to be regarding rainfall potential, precipitable water and warm cloud depth values are not extreme, but seasonally high vs climatology promoting efficient rainfall rates. The outflow boundary has reduced confidence in high resolution solutions, but the HRRR, RAP and HopWRF had the best handling on earlier Upper MS Valley convection and suggest the northern few tiers of IA, eastward to the MS river could get hit with heavy rains overnight with 15z ESRL HRRR amounts up to an alarming 5-10 inches and the 15z HopWRF showing high neighborhood probabilities of at least 5 inches over NE IA out of our forecast area. Other models only show a few inches however, which is possible if the stronger Corfidi vector movement makes the convection too progressive north to south. So again it needs to be emphasized that a very high impact event is certainly possible but with somewhat diminished confidence due to model spread and uncertainties. Remember that this uncertainty is also carried over into the current river forecasts which include 48 hours worth of QPF rather than the typical warm season 24 hours. Current QPF depicts a widespread but middle of the road 2-3 inches of rainfall affecting the Winnebago and Cedar basins which results in moderate flooding in several locations. Changes in location or rainfall amounts on either side of that spread could result in lower or higher forecast stages. This is why Hydrological Outlooks rather than warnings have been issued until confidence in locations and magnitude increases.ow chances of anything getting rooted surface based at the moment. Convergence is shallow per the lack of 0-2km moisture convergence and surface winds east of the boundary are veering suggesting a downward trend in overall convergence. Some strong to severe elevated storms are still possible however with higher effective shear and ESRH still in place north and east of the boundary. The question into tonight then turns to where new MCS development will occur and its movement. Confidence is not the highest however as none of the models are handling the strength of the outflow boundary well. Examination of 305K isent surfaces show the NAM and GFS focusing 30-40kts of flow and convergence from the Mason City area into southern MN while the latest Rap washes this out more and highlights MN. The latest objective analysis shows the 925/850mb fronts and associated frontogenesis into MN so this would appear to be the favored MCS genesis region. It does not mean IA will be spared however. The strength of the inflow results in Corfidi vectors with a pronounced southern motion suggesting the MCS will eventually be drawn into IA. MUCapes of a few thousand should persist into the night with around 30kts of effective shear suggesting severe storms would remain possible with favorable shear orientation north to south into IA. .LONG TERM.../Thursday night through Wednesday/ Issued at 344 PM CDT Wed Sep 21 2016 Little change in going forecast for the next few days. Confidence in overall trends for heavy rainfall potential remains high...but details still debatable due to daily mesoscale interactions. By early Thursday morning still expecting ongoing convection across the north with old outflow boundary still the focus for some thunderstorm activity over the north half of the forecast area. Though the better forcing will be in the overnight period tonight...there will still be enough instability during the morning and afternoon hours to promote thunderstorms with locally heavy rainfall potential over the north half of the forecast area. Will maintain FFA across the area through tomorrow afternoon. Through the night another strong push of thetae advection will precede the next upstream wave propagating northeast by 12z Friday. Most of any convection should be confined to the north third Thursday night and north into Minnesota. With the boundary holding on there will still be the potential for additional locally heavy rainfall across the north. If trends continue... there may be a need for an extension of headlines there. By 12z Friday models push the warm front well into southern Minnesota. This will temporarily limit convection over our area as all of the forcing will be moving north. With the warm sector fully realized once again Friday...highs will move back into the upper 80s to lower 90s during the afternoon hours. Surface dew points will again remain rather uncomfortable in the mid to upper 60s...with heat indices well into the 90s by late afternoon. With the approach of an upper level trough over the northern Plains Saturday a cool front will move into the area by 12-18z. Models have advanced the front a bit faster...though the boundary begins to slow as it crosses the region from Sunday through Monday morning. Unfortunately... the tropical moisture feed will remain intact just along and east of this boundary. There is some uncertainty but if the boundary is hung up long enough additional moderate to locally heavy rainfall amounts of 1 to 2 inches may occur over the region between Saturday evening and Monday morning...especially east of I35. The GFS and Euro diverge thereafter...with the GFS focusing the boundary southeast of the region from Monday through Wednesday. The Euro holds the boundary over eastern Iowa and with a more northerly track of the northern Plains system into midweek next week as well as a rather strong southern stream H500 system developing by 12z Monday. The GFS has the northern system looping back southeast by 00z into the Central Plains with virtually no southern stream component at H500 at that time. The result here is that the surface boundary and rain is pushed out of the region by the GFS. For comparison...the GEM is even slower and farther west than the Euro. At this time...will have to weight the Euro/GEM solutions a bit higher and will need to closely monitor trends through the weekend. If the latter proves a better solution...the resultant rainfall over the region could additionally add several more inches of precipitation on top of what is projected through Monday. The reason...both the direct fetch from the Gulf and potential for another old tropical system being injected into the area from the southern Plains. Highs next week should be cooler with extensive cloud cover and chances for rainfall. && .AVIATION.../For the 00Z TAFS through 00Z Thursday evening/ Issued at 640 PM CDT Wed Sep 21 2016 Storms continue to form right near KMCW, so have continued the mention of TSRA this evening. Looks like there should be a break late this evening, before more storms form across southern MN and drop southward impacting KMCW toward 06Z or so. Otherwise storms moving southward may roll through the northern TAF sites and near KDSM with lingering shower activity into Thursday. Winds remain out of the south. Expect CIGS around MVFR to low VFR with the storms. && .HYDROLOGY... Issued at 344 PM CDT Wed Sep 21 2016 Regarding rainfall potential, precipitable water and warm cloud depth values are not extreme, but seasonally high vs climatology promoting efficient rainfall rates. The outflow boundary has reduced confidence in high resolution solutions, but the HRRR, RAP and HopWRF had the best handling on earlier Upper MS Valley convection and suggest the northern few tiers of IA, eastward to the MS river could get hit with heavy rains overnight with 15z ESRL HRRR amounts up to an alarming 5-10 inches and the 15z HopWRF showing high neighborhood probabilities of at least 5 inches over NE IA out of our forecast area. Other models only show a few inches however, which is possible if the stronger Corfidi vector movement makes the convection too progressive north to south. So again it needs to be emphasized that a very high impact event is certainly possible but with somewhat diminished confidence due to model spread and uncertainties. Remember that this uncertainty is also carried over into the current river forecasts which include 48 hours worth of QPF rather than the typical warm season 24 hours. Current QPF depicts a widespread but middle of the road 2-3 inches of rainfall affecting the Winnebago and Cedar basins which results in moderate flooding in several locations. Changes in location or rainfall amounts on either side of that spread could result in lower or higher forecast stages. This is why Hydrological Outlooks rather than warnings have been issued until confidence in locations and magnitude increases. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Thursday evening for IAZ004>007- 015>017. Flash Flood Watch through Thursday evening for IAZ023>028- 033>039-044>048. && $$ SHORT TERM...Small LONG TERM...REV AVIATION...Beerends HYDROLOGY...Small
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1148 PM EDT WED SEP 21 2016 .AVIATION... Remnant showers/thunderstorms are still expected to largely pass north of the southeast Mi terminals overnight and this morning. There is a small chance that a stray shower/thunderstorm may impact MBS. Given the trends for convection to weaken as it approaches the more stable mid level profile over Lower Mi, the chance of a thunderstorm will continue to be left out of the MBS TAF. Despite periodic high clouds traversing the area, boundary layer moisture and radiational cooling have already led to some fog development. This has been more extensive across the Saginaw Valley where afternoon low level moisture advection was a little stronger. Observational trends certainly support maintaining a mention of fog in the terminals through daybreak. The likelihood of additional cirrus debris advancing across the area during the early morning may slow the pace of cooling and thus suggests refraining from going too low with early morning visibilities just yet. For DTW... There was a weak southeasterly wind off Lake Erie this evening which nudged sfc dewpoints up a little. The thicker cirrus should also remain farther north and west. So radiational cooling will provide a good chance for some MVFR type vsby in fog around daybreak. //DTW Threshold Probabilities... * None && .PREV DISCUSSION... Issued at 927 PM EDT Wed SEP 21 2016 UPDATE... Radar/Satellite imagery indicates at least a couple short wave featured across nrn Wisconsin. These impulses will track across Upper Mi and the straits tonight into Thurs morning. This will allow showers and a few thunderstorms to slowly extend from nrn Wisconsin into northern Michigan, while the deeper convection holds well west of the area within the quasi stationary convective clusters across MN/IA/wrn Wi. There will remain a localized region of mid level subsidence and associated drier mid level air across Se Mi tonight well into Thursday. This should largely hold the more organized showers and thunderstorms to the north and northwest of the forecast area overnight and Thursday. Given how far south some of the convection has developed in ern Wisconsin this evening, it seems plausible that some stray showers/isolated thunderstorms may impact the Saginaw Valley and tip of the thumb overnight. This fully supports the low chance pop in the forecast (along and north of a Saginaw to Sandusky line) overnight and during the day Thursday. The only update to the forecast will be to push the chances of rain back a few hours tonight based on current trends and to lower forecast min temps a couple degrees in the thumb where current temps are already nearing forecast lows. PREV DISCUSSION... Issued at 344 PM EDT Wed SEP 21 2016 DISCUSSION... Energetic upper levels continue through mid week as a nearly zonal 140+ knot jet streaks across the US/Canada border. Weak southern stream jet lifting northeast out of the developing west coast upper level trough, will send a series of shortwaves through the plains and into northern MI. The pattern has also resulted in a broad surface developing over the central plains with a warm front taking shape across the Central Great Lakes. This pattern will deviate very little now through the end of the week as the strong Hudson Bay low remains in place. Area should remain dry through the rest of the evening and into the overnight hours as subsidence in the wake of the early afternoon MCS settles over southern MI. Hires HRRR and RAP advertise some redevelopment this evening along I94 on the sinking outflow boundary but confidence is low in the occuring. The current cap will make it hard for anything to develop, even with a bit of late afternoon heating. Radar trends through the day have shown the convection struggling to advance much further west than Chicago away from the stronger height falls. Without any forcing locally and no shortwaves to speak of during the evening, think convection will struggle even with peak heating as skies begin to clear out somewhat. Tonight through Friday will focus on the warm frontal positioning and shortwaves/MCSs that will ripple along the front for possible showers and thunderstorms. Models have shifted north with the positioning of the surface front which in turn refocuses the developing isentropic forcing north. A brief shortwave ridge rounding the base of the Hudson Bay low will allow the jet to arch northward as well which will steer the approaching shortwaves further north as well. All this leads to shifting the pops north which really only leaves the Saginaw Valley and northern Thumb with a short at precip through Thursday. Will highlight the period from 09-15Z Thursday for the best opportunity as the shortwave lifts through northern lower aided by nocturnal low level jet and next surge of theta e. The rest of the afternoon will likely dry out for everyone again but with the front just to the north will leave a slight chance for the extreme north. The front will start to sag southward into mid MI Thursday night as a strong trough rotates around the Hudson Bay low giving it a push. It should passing through southeast MI by Friday afternoon which will be the next chance for showers and thunderstorms. Should see a good thermal gradient across southern MI on Friday with the front draped across the region. This will mark the end of the current stretch of 80 degree days as highs north of I69 will struggle to reach 70 with strengthening northeast flow off Lake Huron. Timing of the front will decide just how warm the Metro Detroit area can get before cooling back off. High pressure over Ontario will keep surface flow with an easterly component locally over the weekend. Sharp NW/SE low-mid level theta-E boundary across SE MI, and cannot totally rule out some light showers Saturday with weak positive theta-E advection and PWAT around 1.5 inches, but at this point expect most of the weekend to be dry. Low predictability early next week with guidance indicating a cutoff low taking shape somewhere to our west over the Northern Plains/Upper Midwest, with meridionally-oriented moisture plume ahead of it. Eastward progression of these features will determine rain chances early next week, and not a whole lot of model consensus at this point, so chance PoPs early next week will suffice for now. Despite rather warm mid-level temps, easterly surface flow is expected to keep temps in check near or slightly above normal. MARINE... A front will remain stalled over the northern Great Lakes tonight through Thursday. An active pattern of showers and thunderstorms will be the primary marine weather impact, mainly over northern Lake Huron, while wind and waves remains light/low over other marine areas. That will change Thursday night and Friday as the front settles southward into Ohio and opens moderate northeast flow over all areas. The long fetch of onshore, unstable flow over southern Lake Huron and into Saginaw Bay will likely produce waves exceeding SCA levels through Friday night before high pressure settles in Saturday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....SC UPDATE.......SC DISCUSSION...DRK/DT MARINE.......BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Goodland KS
532 PM MDT WED SEP 21 2016 .UPDATE... Issued at 527 PM MDT Wed Sep 21 2016 Added areas of fog and low clouds for northwest half of the area after midnight and into Thursday morning. HRRR suggests both will develop as cold front sags southward overnight and post frontal low level upslope develops. && .SHORT TERM...(This evening through Thursday) Issued at 1210 PM MDT Wed Sep 21 2016 Midday analysis of satellite and radar indicate only partial clearing for the western half of the CWA with very light isolated showers in the eastern portions of the area. High resolution data does not develop much in the way of precipitation through the afternoon hours with only isolated slgt chc to chc showers expected through the afternoon and into the evening. Should start to see some isolated activity in the east and southeastern portions of the CWA with areas west and northwest remaining dry. Temperatures have been steadily rising through the morning and we remain on track to reach our afternoon high in the lower 90s. Lows tonight should fall into the middle 50s to middle 60s but this will be cloud cover dependent as the temperatures will be slower to respond in areas with persistent cloud cover. Another warmer than average day is in store tomorrow with high pressure positioned just far enough west to continue the influence on our temperatures. Subsidence on the western fringe of the ridge combined with relatively dry air at the surface will keep precipitation out of the forecast through Thursday afternoon. Highs should once more reach the lower 90s. .LONG TERM...(Thursday night through Wednesday) Issued at 224 PM MDT Wed Sep 21 2016 For the extended period...the main wx concern will focus on a strong upper low/trough which currently sits off the Pacific coast. This system will move northeast thru Rockies slowly Thursday night on thru the upcoming weekend...and eventually set up over the Northern Plains region before becoming a cutoff/meandering upper system by next Monday into the middle of next week. The first chance for precipitation during the extended occurs as a weak warm front lifts thru the region thursday night...followed by a cold front for the overnight period into Friday. These occur out ahead of the upper trough as it lifts thru the Rockies. Enough instability ahead of the front will warrant mention from SPC of a Marginal risk for some isolated t-storms w/ the main focus along the KS/CO border. The latter half of the extended period will focus on the WNW circulation over the area. The combination of the upper low over the Northern Plains and surface high pressure over the NC Rockies will keep breezy conditions in place. Overall...increased cloud cover thru the period possible with a few weak shortwaves rounding the low circulation to help enhance. For temps...above normal numbers expected before the passage of the cold front...then the increased WNW surface flow will usher in a cooler airmass with temps at or just below normal. Looking for highs to range in the 78-88 range to start...tapering down to mainly the mid to upper 60s for the remainder. Overnight lows taper down from near 60F to mainly the 40s by next Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 527 PM MDT Wed Sep 21 2016 Main aviation concern will be the possibility of low clouds and reduced visibility in fog overnight and into Thursday morning. A cold front will sag southward tonight and both are expected to develop in the post frontal low level upslope environment. Conditions will gradually improve through Thursday morning. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...024 SHORT TERM...TL LONG TERM...JN AVIATION...024
Area Forecast Discussion
National Weather Service Green Bay WI
1040 PM CDT WED SEP 21 2016 Updated aviation portion for 06Z TAF issuance .UPDATE... Issued at 1037 PM CDT Wed Sep 21 2016 Considered trimming back the northern and eastern portion of the Flash flood Watch this evening with current radar trends. After a period of heavy convection over parts of Central Wisconsin early this evening, precipitation has shifted to a stratiform type of rain over much of the area including northern wisconsin. Radar rainfall rates were much higher across the north compared to ground truth. Recent nam has shifted rain to the north tonight, so was reluctant to pull any headline at this time. In addition convection was developing upstream over East Central Minnesota and will be working into the state overnight and PWATS were forecast to increase. Will let the overnight crew adjust headlines with the next suite of data. Will likely cancel flash flood warnings for now but head to areal due rising rivers. && .SHORT TERM...Tonight and Thursday Issued at 226 PM CDT Wed Sep 21 2016 The latest RAP analysis and satellite/radar imagery show a surface warm front snaking from southern Minnesota to northern Illinois early this afternoon. Showers and thunderstorms continue to fire along the boundary over the same areas that received heavy rainfall last nite, namely southeast Minnesota and southern Wisconsin. Additional storms are firing over western Wisconsin in a region of low level moisture convergence. These storms will likely continue to develop and push into the I-39/route 51 corridor later this afternoon. An isolated severe storm will be possible from Lincoln to Waushara counties with mu capes above 1000 j/kg and 0-6 km shear of 45-50 kts. As a weak shortwave lifts across the Plains and into the western Great Lakes tonight, thunderstorm trends and potential for heavy rain/severe weather are the main forecast concerns. Tonight...An active period of weather, with an atmosphere conducive for heavy rainfall. A weak shortwave, currently over southwest Nebraska will lift northeast and across the region late tonight. Ahead of the shortwave, a strengthening 30-40 kt low level jet is anticipated to ride over the slowly northward advancing warm front later this afternoon into this evening. With ample instability and shear as shown on mesoanalysis imagery, showers and thunderstorms are expected to develop and expand upstream of the current thunderstorm activity over southern and central Minnesota, before sliding east through the night. Elevated capes of 1000-1500 j/kg suggest a severe storm cannot be ruled out through the evening, especially over areas from west of the Fox Valley and south of route 29. In addition, long duration of forcing combined with plentiful moisture (pwats of 1.75 to 2.00) continues to imply that a flood or flash flood threat is possible. The latest guidance shows that central WI from Lincoln to Waushara counties have the most risk for receiving heavy rainfall, with amounts of 1-3 inches possible (locally higher). Though concerns are not as high for flooding further east within the flood watch, potential for heavy rain will remain, especially over the southern Fox Valley where rainfall over an inch has already fallen early this morning. Temps ranging from the mid 50s north to mid 60s south. Thursday...Model guidance continues to show that the front will remain stalled over central and northeast Wisconsin. Though weak shortwave impulses will be passing to the east during the morning, periods of showers and storms will likely continue through the day. Weaker forcing and instability suggests rainfall only has a limited potential to be on the heavy side, so thinking additional amounts of a quarter to a half inch will be possible, locally higher in storms. With the rainfall and clouds, temps will remain cooler in the mid 60s to mid 70s. .LONG TERM...Thursday Night Through Wednesday Issued at 226 PM CDT Wed Sep 21 2016 A frontal boundary that was just to the southwest of Wisconsin early this afternoon is the main concern through the end of the week before a surface low pressure system brings a cold front into the state. The approaching warm front will keep at least a chance for showers and thunderstorms in the forecast through Saturday morning. Central and east central Wisconsin will be the main concern for heavy rainfall since the front is expected to be in that general area before it finally makes a stronger push to the northeast and clears the state late in the week. Looks like there could be a period of dry weather, with not even a slight chance POP, Saturday afternoon but confidence in timing is low. Have shower and thunderstorm chances returning with the approach of a cold front from the west, which may take a while to clear the state. The 12Z GFS, ECMWF and Canadian all started to exhibit significant differences for early next week but all looked quite wet through the end of the forecast period. Highs during the day should be within a couple of degrees of normal, and lows should be warmer than normal due to all of the clouds and rain. && .AVIATION...for 06Z TAF Issuance Issued at 1040 PM CDT Wed Sep 21 2016 A nearly stationary frontal boundary extending from west to east over the state will be a focus of showers and storms tonight into Thursday. Cigs and vsbys will continue to deteriorate tonight and continue into Thursday. Slightly drier air across parts of northeast Wisconsin were keeping vfr conditions lingering late this Wednesday evening. && .GRB WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Thursday evening FOR WIZ018>020-030- 031-035>040-045-048>050. && $$ UPDATE.........TDH SHORT TERM.....MPC LONG TERM......MG AVIATION.......TDH
Area Forecast Discussion
National Weather Service Wilmington NC
1125 PM EDT Wed Sep 21 2016 .SYNOPSIS... The remnant circulation of former Tropical Storm Julia will maintain scattered showers through Friday. Drier weather should develop Saturday as high pressure pokes in from the north. A cold front will move through early Sunday, followed by several days of onshore winds and slightly cooler temperatures next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 1030 PM Wednesday...Have upped POPs to likely as convection over the adjacent Atl waters has already begun its development and its push inland. Already, a few cells have pushed onshore. One of them went directly over ILM ASOS, and deposited 0.85 inches of rainfall in 30 minutes. With PWS at or higher than 2.00 inches, this pcpn activity will be quite zealous in its production of QPF amounts. Have updated the QPF with hier amounts for the overnight period. No lightning strikes with this activity at the moment. Will continue to mention isolated thunder...and the heavy rain phraseology. Have upped mins, hourly temps and dewpts by 1 to 3 degrees across the ILM CWA due to the clouds and pcpn. Previous..................................................... As of 815 PM Wednesday...Main feature, the upper low, initially will be directly overhead this evening. During the overnight, models are in a general agreement in the upper low meandering slightly to the southwest. This will result instead of a northerly component to the winds aloft early this evening, winds aloft will become more SE to S oriented due to the counterclockwise rotation around this upper low. Thus instead of wraparound moisture, will be dealing with direct moisture from off the Atlantic. PWs will increase to over 2.00 inches across the majority of the ILM CWA, except the far NW portions will it remain below. This via latest GFSbufr soundings. The onshore movement of pcpn will pick later tonight, mainly during the pre-dawn THU hours thru the late morning daytime Thu hrs. This to reflect the nocturnal Atlantic engine revving up an area of showers and tstorms followed by the onshore movement then redirected toward the wsw-sw, associated with the upper low`s circulation. The pcpn over the north and west of the I-95 corridor will be far lighter with no deep convection. Again, the deeper convection and threat for thunder will remain closer to the coast. With high PWs, the rainfall accompanying the stronger activity will be highlighted with heavy rain phraseology. This already occurring over a 10-20 mile wide band of convection extending from Burgaw, across Bolton and Tabor City to Pamplico. Other concern will be another night of widespread low stratus, which seems feasible except along the immediate coast where pcpn will be moving onshore. Current min temp fcst looking aok.$$ AMZ250-220745- COASTAL WATERS FROM SURF CITY TO CAPE FEAR NC OUT 20 NM- 827 PM EDT WED SEP 21 2016 .OVERNIGHT...E WINDS 10 KT. SEAS 2 TO 3 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .THU...NE WINDS 10 KT. SEAS 3 FT. SHOWERS LIKELY WITH ISOLATED TSTMS. .THU NIGHT...E WINDS 10 KT OR LESS. SEAS 3 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI...NE WINDS 10 KT OR LESS...INCREASING TO 10 KT IN THE AFTERNOON. SEAS 3 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI NIGHT...NE WINDS 10 KT. SEAS 3 FT. A SLIGHT CHANCE OF SHOWERS WITH ISOLATED TSTMS. .SAT...NE WINDS 10 KT. SEAS 3 TO 4 FT. .SAT NIGHT...E WINDS 10 KT. SEAS 3 FT. .SUN...E WINDS 10 KT. SEAS 3 TO 4 FT. .MON...E WINDS 10 TO 15 KT. SEAS 3 FT. WINDS AND SEAS HIGHER IN AND NEAR TSTMS. $$ AMZ252-220745- COASTAL WATERS FROM CAPE FEAR NC TO LITTLE RIVER INLET SC OUT 20 NM- 827 PM EDT WED SEP 21 2016 .OVERNIGHT...E WINDS 10 KT. SEAS AROUND 2 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .THU...NE WINDS 10 KT. SEAS 2 TO 3 FT. SHOWERS LIKELY WITH ISOLATED TSTMS. .THU NIGHT...SE WINDS 10 KT OR LESS. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI...E WINDS 10 KT OR LESS. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI NIGHT...NE WINDS 10 KT. SEAS 2 TO 3 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .SAT...NE WINDS 10 KT. SEAS 2 TO 4 FT. .SAT NIGHT...E WINDS 10 KT. SEAS 2 TO 4 FT. .SUN...E WINDS 10 KT. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS AND TSTMS THROUGH THE NIGHT. .MON...E WINDS 10 TO 15 KT. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS AND TSTMS THROUGH THE NIGHT. WINDS AND SEAS HIGHER IN AND NEAR TSTMS. $$ AMZ254-220745- COASTAL WATERS FROM LITTLE RIVER INLET TO MURRELLS INLET SC OUT 20 NM- 827 PM EDT WED SEP 21 2016 .OVERNIGHT...E WINDS 10 KT OR LESS. SEAS 2 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .THU...NE WINDS 10 KT. SEAS 2 TO 3 FT. SHOWERS LIKELY WITH ISOLATED TSTMS. .THU NIGHT...E WINDS 10 KT OR LESS. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI...E WINDS 10 KT OR LESS. SEAS 2 TO 4 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI NIGHT...NE WINDS 10 KT. SEAS 2 FT. A SLIGHT CHANCE OF SHOWERS WITH ISOLATED TSTMS. .SAT...NE WINDS 10 KT. SEAS 2 TO 3 FT. .SAT NIGHT...E WINDS 10 KT. SEAS 2 FT. .SUN...E WINDS 10 KT. SEAS 2 TO 3 FT...BUILDING TO 2 TO 4 FT. A CHANCE OF SHOWERS AND TSTMS THROUGH THE NIGHT. .MON...E WINDS 10 TO 15 KT. SEAS 2 TO 3 FT. A CHANCE OF SHOWERS AND TSTMS. WINDS AND SEAS HIGHER IN AND NEAR TSTMS. $$ AMZ256-220745- COASTAL WATERS FROM MURRELLS INLET TO SOUTH SANTEE RIVER SC OUT 20 NM- 827 PM EDT WED SEP 21 2016 .OVERNIGHT...E WINDS 10 KT OR LESS...INCREASING TO 10 KT. SEAS 2 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .THU...NE WINDS 10 KT. SEAS 2 TO 3 FT. SHOWERS LIKELY WITH ISOLATED TSTMS. .THU NIGHT...E WINDS 10 KT OR LESS. SEAS 3 FT. SHOWERS LIKELY WITH ISOLATED TSTMS. .FRI...E WINDS 10 KT OR LESS. SEAS 3 FT. A CHANCE OF SHOWERS WITH ISOLATED TSTMS. .FRI NIGHT...NE WINDS 10 KT OR LESS. SEAS 3 FT. A SLIGHT CHANCE OF SHOWERS WITH ISOLATED TSTMS. .SAT...NE WINDS 10 KT. SEAS 3 FT. .SAT NIGHT...E WINDS 10 KT. SEAS 3 FT...SUBSIDING TO 2 FT AFTER MIDNIGHT. .SUN...E WINDS 10 KT. SEAS 2 TO 3 FT...BUILDING TO 3 TO 4 FT. A CHANCE OF SHOWERS AND TSTMS THROUGH THE NIGHT. .MON...E WINDS 10 TO 15 KT. SEAS 3 FT. A CHANCE OF SHOWERS AND TSTMS. WINDS AND SEAS HIGHER IN AND NEAR TSTMS. $$ DCH Previous........................................................ As of 300 PM Wednesday...Low pressure over southeast NC will drift slowly SW becoming more elongated along the SC coast by this evening with a trough extending northward from center of low. An easterly on shore flow will exist on the front end of low/east side of trough along the coast and continued NE-N flow inland, on back end of low/west side of trough. This pseudo warm front/trough will provide a warmer easterly flow and will allow for some drying and thinning of the clouds. At the same time energy will continue to rotate around this upper low combining with deeper layer moisture inland to produce showers and isolated thunderstorms wrapping around to the S-SE into Northeast SC. Pcp water values show a plume of deeper layer moisture with values over 2 inches running from VA/NC coast around to the SW to S through central NC/SC. Coastal NC will have some drier air wrapping around from the S to SE with pcp water values down closer to 1.7 inches this aftn. Overall, instability will remain marginal due in part to significant cloud cover, so although clouds will blanket most of the area, expect modest QPF amounts of most areas with greatest amounts aligned inland mainly just west of I-95 corridor. If areas break out along the coast, expect some heating and differential heating to produce some further convective development mainly across central portions of forecast area inland from the coast. As this deep low drifts S-SW toward the GA/SC coast through tonight, some deeper layer moisture will wrap back around over the Cape Fear region and should increase shwr activity over the eastern portions of the forecast area overnight as moisture and showers spread from the coastal waters along the coast in a deeper E-SE flow. Expect mainly light to moderate rain but some embedded heavier rain amounts are possible. Overall the cool pool aloft and continued moist flow will produce plenty of clouds and potential for pcp through tonight. Temperatures inland in northerly flow on back side of low will remain in the mid 70s this aftn while temps along the coast will reach over 80 especially where some breaks or thinning in the clouds occurs. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...The persistent mid to upper low will become more elongated and may drift westward before opening up into a trough along the east coast and moving off shore by Fri night. The center of the low will remain south of the area with trough extending northward maintaining a deeper on shore flow through the period. The trough looks like it will be just along or off shore which will keep a N-NE flow over much of the area but should see more of an E-SE flow at times along the coast and off shore as trough and diurnal shifts take place. Pcp water values will remain up above 1.75 inches through much of the period in a very moist air mass. With such deep layer moisture and a deep low/trough over the region through the period, expect unsettled weather to continue. While POP areal coverage should remain scattered most of this period, there will be bands of showers with more moderate to heavy rain across portions of the area associated with upper level energy rotating around over the region. Drying will finally take place late Fri into early Saturday as trough finally moves off to the east. Skies will begin to clear from west to east leaving partly cloudy skies by Fri night over most places. Max temps will reach near or around 80 during the afternoons overnight lows near 70 Thurs night but slightly lower Fri night as some clearing occurs. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 300 PM Wednesday...The upper levels will certainly not look anything like summer with a very amplified trough-ridge-trough pattern expected to develop across North America. Models have struggled to form a consensus over the past few days with details, however the new 12z GFS may be on to something with its depiction of an Omega block developing by Tuesday. Due to this blocked pattern, the potential of a strong cold frontal passage late this month is now in jeopardy and we may remain in the tropical/subtropical humidity through the remainder of September. A 500 mb ridge centered across the Mississippi Valley on Saturday will only slowly work east into the Carolinas by Tuesday and Wednesday. A deep upper level low moving across the Canadian Maritime provinces will push a cold front southward along the East Coast, reaching the Carolinas early Sunday. The surface high behind this front won`t dive south, and in fact may only reach coastal New England by late Tuesday or Wednesday. This will create an extended period of onshore winds and the potential for scattered showers as a band of convergence behind the old front could settle across the area, coincident with at least shallow Atlantic moisture. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... As of 00Z...A low level convergence boundary will affect LBT and FLO through about 01Z, with most of the convection dissipating after that. Overnight, fairly high confidence for IFR conditions at all locations with abundant low level moisture. Surface low pressure will have convection on the increase toward morning at ILM, well depicted by the HRRR model. This precip will likely continue through early afternoon, spreading inland after that. Light mainly northeast flow through midday on Thursday. EXTENDED OUTLOOK...Isolated to scattered afternoon and early evening convection possible underneath the cutoff upper low through Friday. MVFR/IFR morning stratus/fog possible each day through Sunday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1030 PM Wednesday...This update concerned with PCPN coverage. Have upped the shra and isolated thunder coverage overnight based on latest 88D trends and near term Model guidance ie. HRRR and the RAP. Previous..................................................... As of 830 PM Wednesday...Have increased the coverage and POPs associated with the development of convection over the Atlantic waters during the pre-dawn Thu hours thru mid to late daytime morning Thursday. The cloud to ocean lightning strikes will be limited, however the main concern will be the reduced VSBY, less than 1 nm at times, caused by the heavy rainfall. Current wind fcst will mainly be from an easterly direction, with a relaxed sfc pg, speeds will be around 10 kt. Significant seas will run 2 to around 3 ft. This depends on how much of an influence the T.S. Karl fore-runners have on the local waters. At this point, wavewatch3 and local Swan models, both indicate a 1.5 to 2.5 foot ese hurricane swell at 10-12 second periods. This will become the dominating feature to the significant seas spectrum by daybreak Thu. Previous....................................................... As of 300 PM Wednesday...A deep low over the Cape Fear region will drift southwest through tonight. This will result in a weak pressure gradient with winds 10 knots or less through the day. Wind direction will also be somewhat variable, but in general, an onshore flow will continue as the low center drifts southwest. It should kick back to a more northeasterly direction close the coast on the back end of the low and more E-SE farther off shore on the front end of low. Mid- level dry air over the waters is expected to limit storm development today, but should increase overnight in deeper on shore flow. Seas will remain less than 3 ft mixing in with some longer period SE swells arriving tonight. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 PM Wednesday...Low pressure will weaken south of the waters with trough aligned up the coast through the period. This will keep an on shore flow through the period and depending on the exact position of the trough, the winds will fluctuate between E-SE to E-NE over the waters...remaining 10 kts or less. Winds will turn more northerly and pick up a bit by Fri night as low finally moves off to the east. Showers and isolated TSTMS will remain in the mix. Seas will basically remain 3 ft or less with a slight, slow and steady rise as a longer period up to 12 second SE swells mix in. LONG TERM /SATURDAY THROUGH MONDAY/... As of 300 PM Wednesday...Julia`s remnants should be long gone from the weather map by Saturday. High pressure dropping southward from the southern portion of Hudson Bay will push a cold front through the Carolinas early Sunday. This front will sink to coastal Georgia Monday with easterly winds developing across the Carolinas. Scattered showers should develop mainly behind the front beginning Sunday night. Wave heights of 2-3 feet are expected south of Cape Fear Saturday into the first half of Sunday, with the potential for 3-4 foot seas near and north of Cape Fear due to residual swells emanating from distant Tropical Storm Karl. By Sunday night modest onshore winds will create the potential of shorter period 2-4 foot waves away throughout the area, continuing into Monday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...TRA NEAR TERM...DCH/RGZ SHORT TERM...RGZ LONG TERM...TRA AVIATION...DL MARINE...
Area Forecast Discussion
National Weather Service Northern Indiana
751 PM EDT Wed Sep 21 2016 .SYNOPSIS... Issued at 326 AM EDT Wed Sep 21 2016 High pressure will continue to provide fair weather as it remains stationary across the area through Thursday night. Lows tonight and Thursday night will be in the lower to middle 60s, with highs Thursday and in the mid 80s. A weak cold front will move across the area Friday, bringing a slight chance of thunderstorms northeast of a South Bend to Defiance line. Slightly cooler air will follow the front into the area over the weekend. A slow moving low pressure system is expected to move into the area early next week bringing our next chance of rain. && .SHORT TERM...(This Evening through Thursday) Issued at 324 PM EDT Wed Sep 21 2016 So far upstream convection has behaved as advertised and continues to weaken as it moves east out of deeper instability and away from stronger synoptic forcing. HRRR still wants to occasionally develop an isolated cell in our north through 00z with modest instability and decent mid level lapse rates. So far outflow boundaries have not been strong enough to force any development. Vis sat loop does show some cu trying to develop over the northwest in vicinity of where HRRR has tried to convect. Also watching remnant convection sliding southeast from northern Illinois. Will carry the slight chance pops over the north and northwest through 00z followed by dry conditions for the overnight period as main front lifts north. This boundary now looks to reside far enough north on Thursday that pcpn chances will be 10 percent or less and upstream convective complex tonight over WI to stay north of our area tomorrow. Should still see some cloud debris but expect more sun than today and temps will once again recover nicely well into the 80s. ECE MOS kicking out upper 80s over parts of the region but will hold shy of this in the mid 80s with the potential for the debris clouds at times. && .LONG TERM...(Thursday Night through Wednesday) Issued at 324 PM EDT Wed Sep 21 2016 Upper level pattern to transition from zonal to a meridional flow through the period. This will complicate forecast by early next week with various model solutions revolving around cut off upper low and an occluded front. Backdoor front will begin to slide into the area later Friday and Friday night. Moisture limited and not much synoptic forcing. Slight chance pops continue in the northeast. This boundary will bring northeast winds and cooler temps through the weekend but still above normal for late September. Highs in the middle to upper 70s still expected. More uncertainty exists with potential frontal boundary early next week. GFS and ECMWF continue to have differences with respect to a cut off upper low over the central CONUS and how an occluded front associated with it will translate east. GFS continues to be faster model while ECMWF remains slower. These differences being dictated by large trough off the northeast CONUS and stout ridge between that trough and the developing upper low over northern Plains. GFS wants to push sfc boundary through the ridge while ECMWF stalls this boundary to our west. For now will be using the Superblend init until more certainty develops. Preference is toward ECMWF as GFS has a bias of breaking down ridges and seems to be doing that here as well. Temps remain mild in the 70s but should trend closer to normal next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) Issued at 733 PM EDT Wed Sep 21 2016 Sfc ridge extending from the ne U.S. across IN will persist through the period resulting in dry conditions. TS will continue to develop along a stnry front across WI/MN/IA and propagate sewd but dissipate or turn more s-sw toward unstable airmass over the MS valley with just some mid-high clouds advancing across our area. Given stagnant airmass over the area, a repeat of mvfr vsbys in br around dawn likely again in the Maumee valley including fwa Thu morning. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...jt SHORT TERM...Lashley LONG TERM...Lashley AVIATION...JT Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion
National Weather Service Medford OR
857 PM PDT WED SEP 21 2016 Updated to include information about snow in the Cascades. .SHORT TERM...The upper level low over the area has brought isolated thunderstorms and scattered showers this evening across inland areas including Douglas, Josephine, Jackson, Siskiyou and Klamath Counties. The chance for thunderstorms will continue late this evening but expect storms to remain isolated. Also the best area for storm development will be over central and eastern Siskiyou, Klamath and western Lake counties. These storms have mainly brought light to moderate rain with occasional lightning. After midnight, models continue to show that thunderstorm chances will diminish but showers will continue for as the low remains in place over the area. The best chances for showers will be from the from the I-5 corridor eastward. The high resolution HRRR also shows some isolated showers along the coast from around Cape Blanco southward tonight. So have added a slight chance for showers to these coastal areas. Of note, models are highlighting the around 0.1 to 0.2 inches of precipitation in the Cascades overnight into early Thursday morning. With the cold air mass moving into the area and snow levels lowering to around 6000 feet elevation, expect these showers to bring 1 to 3 inches of snow to the higher portions of the Southern Oregon Cascades. Snow is expected to melt fairly quickly though due to warm ground temperatures. Otherwise, the forecast remains on track for Thursday with continued showers expected for inland areas Thursday morning and then the focus of showers will shift more from the Cascades east in the afternoon. A slight risk for thunderstorms is also expected in east side areas, mainly over Modoc and Lake Counties Thursday afternoon. As the low moves east of the area Thursday evening, expect diminishing showers. Behind the low, a cold air mass will be in place across the east side Thursday night and Friday morning, with low temperatures expected near or below freezing for valleys east of the Cascades. && .AVIATION...21/18Z TAF CYCLE...The main concern through this evening will be gusty winds which could cause some turbulence east of the Cascades especially near thunderstorms where winds could become gusty and erratic. There is a slight chance for thunderstorms in the Cascades, Siskiyous and across Siskiyou and Klamath counties late this afternoon and evening. Any storms will end this evening, but showers will persist mainly east of the Cascades. Tonight into tomorrow morning, a good portion of the forecast area will likely become MVFR with increasing moisture in the region. Most areas should clear to VFR by late tomorrow morning, with gusty winds expected east of the Cascades. -BPN/SK && .MARINE...Updated 840 PM PDT Wednesday 21 September 2016...A weak front will move through Friday afternoon...bringing increasing south winds and choppy seas. Long period westerly swell will arrive Friday night into Saturday. A thermal trough will develop Saturday into Sunday...bringing strong north winds and steep seas. The trough will weaken Monday. Winds will diminish and seas will subside at that time. && .PREV DISCUSSION... /Issued 334 PM PDT WED SEP 21 2016/ DISCUSSION...Cooler, breezy, and occasionally wet weather is in store through Friday. A cold upper level trough has reached the coast and will move across the area tonight. Instability will increase this evening and will result in at least a slight chance of showers for most of the area through tonight. These will be mainly over the higher terrain...especially over the Siskiyou and Cascade mountains and Cascade foothills. There is also the possibility of a few embedded thunderstorms through this evening. The highest probability of showers along the I-5 corridor will be shortly after midnight into early Thursday morning with the aid of an embedded shortwave. On Thursday, the risk of showers and thunderstorms will shift east with a focus from the Cascades across the east side. Precipitation amounts during tonight and tomorrow will mainly be light with amounts of less than 0.05 inches. But, given the showery nature, some areas in the Cascades may receive around a half an inch. Snow levels will drop from around 7500 feet to around 6000 feet with up to an inch of snow expected. Showers are expected to taper off over the Cascades and east side during Thursday evening with a lingering slight chance of thunderstorms over the Warner Mountains of Lake and Modoc Counties. A break between systems on Thursday night will be short. Clouds are expected increase from the west late Thursday night as a weakening warm front approaches. Despite the trend of its strength, it will still be moderately strong as moves into the coastal waters then likely brings rain to the coast during Friday morning. There is a high probability of light west side rain from Friday morning through Friday evening with a chance of rain along the I-5 corridor by early afternoon. Little, if any precipitation will reach the east side during Friday night. A strong high pressure ridge is still indicated to build from the eastern Pacific into our area during the weekend into Monday. This will bring a drastic warming and drying trend with inland high temperatures on Sunday expected to 15 to 30 degrees higher than on Friday. Beyond Monday, model agreement diminishes. There is high uncertainty regarding the strength and timing of a trough that will move out of the Gulf of Alaska toward the Pacific Northwest. The GFS is notably faster and likely too fast with the arrival of this trough. Moisture with the trough is likely to remain mostly and perhaps exclusively north of our area. An associated weak front would likely lead to at least slight cooling toward mid-week and could produce an episode of stronger than typical east side winds. FIRE WEATHER...Updated 100 PM Wednesday 21 September 2016...An upper low is swinging eastward into the forecast area this afternoon. Ahead of this trough, gusty southwest to west winds are expected this afternoon over much of the East Side. Also, a dry slot is being observed on the water vapor imagery pushing over areas east of the Cascades, and this will bring lower humidities to that area this afternoon. Due to these factors, a Red Flag Warning continues for portions of Modoc County this afternoon through early evening. In addition to the gusty winds and low RH, showers and thunderstorms will bring some wetting rains to the forecast area this afternoon through Thursday. We are highly confident that the Cascades north of Highway 140 will receive wetting rains. Several models suggest at least 0.5 inches of rain will fall there this afternoon through Thursday. Additionally, the high terrain of the Fremont NF will likely see wetting rains. Outside of those areas, less than a quarter inch of rain is expected, with the lowest amounts at the coast and in the lowest elevation valleys. The upper low is progressing steadily to the east, and moisture is not impressively deep, so widespread wetting rains across the forecast area are not expected. Thunderstorms are expected in some places today, mainly over higher terrain. Rain will accompany these storms today into tomorrow. Additionally, the air mass is cooling as the upper low moves inland, and snow levels will drop to near 6000 feet by Thursday morning. There will be ongoing showers at this time, so some areas will likely see some snowfall. Crews on fires such as the Soup Complex will experience some cold and potentially wet/snowy weather Thursday morning. Warm frontal precipitation will brush the areas along and west of the Cascades with light precipitation on Friday. The consensus of models suggests the potential for wetting rains again in the Cascades north of Crater Lake, while other areas will likely see less than a tenth of an inch of rainfall. Warm and dry conditions will follow the cool and moist pattern from Saturday through early next week at least. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. Pacific Coastal Waters...None. $$ CC/CC/CC
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1047 PM CDT WED SEP 21 2016 .SHORT TERM...(This evening through Thursday) Issued at 326 PM CDT Wed Sep 21 2016 The next 12 hours will feature widespread showers and thunderstorms across a large portion of Minnesota and western Wisconsin. While a few straight-line wind gusts and a weak tornado are not impossible, the two greater threats this evening are heavy rain with the potential for flash flooding and hail between 1-2" in diameter. You don`t have to be a meteorology major to find the main warm front this afternoon in Minnesota. North of a line from roughly Granite Falls, to the southern Twin Cities metro, to Eau Claire there is overcast skies temperatures in the 60s and northwest surface winds. South of this line, the winds are southerly and temperatures are in the 70s and 80s with dewpoints in the 70s. The instability gradient is stretched out along this line with max values near 3500-4000 J/kg (SBCAPE and MLCAPE) in far south central MN and near 0 J/kg in the far northern TC metro. Good elevated instability and steep mid-level lapse rates extends well north of the surface boundary. In addition to the building instability, the 925-850mb moisture transport and warm advection have increased quite a bit over the past couple hours. The FGEN in this area has also increased since mid afternoon. The result has been the expansion of thunder along or north of the boundary. Storms have been efficient rainfall producers with rain rates between 2-3". The storms have also been efficient hail producers as well, not too much of a surprise given the instability in the hail growth zone, shear profile, and due to the fact that the surface temperatures are in the 60s along and north of the boundary. We expect the radar scope to continue to expand in coverage this evening. The placement of the Flash Flood Watch is still looking good, although some of the convective allowing models are developing convection back farther to the southwest. Though the HRRR has admittedly struggled with the short term trends. Settle in, its going to be a busy night for weather in MN/WI over the next 12 hours. There will likely be elevated hail and heavy rain north of the front that move east northeast, but there will also likely be a broken line of storms that form along the boundary and sag south with time. .LONG TERM...(Thursday night through Wednesday) Issued at 326 PM CDT Wed Sep 21 2016 Highly amplified flow in the extended will evolve into a cut off low which is a pattern that has high uncertainty. For that reason and given the high impact weather expected in the next 24 hours, did not stray from blended guidance in the extended period. There`s a few highlights below. The warm front responsible for the heavy rain will be laid out somewhere along I-90. Storms should continue to Thursday night. On Friday the warm front will lift northward and showers and thunderstorm chances will be tied to the front. There will be warm and dry conditions in the warm sector, but this will be short-lived as a cold front moves in Saturday and brings a few showers and thunderstorms. Beyond this period, the upper level wave will cut off and bring a prolonged period of clouds and light rain. As mentioned above, there is uncertainty in this pattern, so would not be surprised if the forecast changes. The GFS is a bit quicker with the cutoff low, but the ECMWF catches up by the middle of next week. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1047 PM CDT Wed Sep 21 2016 SCT SHRA/TSRA will continue for much of the night across eastern/southern MN and western WI. MVFR ceilings will deteriorate to IFR during the overnight hours and continue Thursday morning before slowly improving back to MVFR for the afternoon/evening. Visibilities will be highly variable due to the precipitation. SCT SHRA/TSRA expected to become dominate again late Thursday afternoon across southern MN with the activity spreading northward Thursday night. Mainly ENE winds 6-12 knots through the period. KMSP...SCT SHRA/TSRA will occur through the first 6 hours of the TAF along with ceilings deteriorating to IFR. Ceilings will be slow to improve during the day. SHRA/TSRA chances rise again Thursday evening. /OUTLOOK FOR KMSP/ Fri...MVFR/SHRA possible. Wind E 5-15kts. Sat...VFR with MVFR/TSRA likely. Wind SE at 10g15kts. Sun...VFR. Wind W-SW 10g20kts. && .MPX Watches/Warnings/Advisories... WI...Flash Flood Watch through Thursday evening for WIZ024-026-028. Flash Flood Watch until 7 AM CDT Thursday for WIZ014>016-023-025- 027. MN...Flash Flood Watch through Thursday evening for MNZ067-069-070- 074>078-082>085-091>093. Flash Flood Watch until 7 AM CDT Thursday for MNZ051>053-059>063- 066-068. && $$ SHORT TERM...CLF LONG TERM...JRB AVIATION...RAH
Area Forecast Discussion
National Weather Service Marquette MI
903 PM EDT WED SEP 21 2016 .UPDATE... Issued at 902 PM EDT WED SEP 21 2016 Based on radar trends showing a sharp back wrn edge of the area of showers moving thru nw WI, diminishing ltg trends within the showers over Upr MI/adjoing nrn WI and more resilient dry air to the n, lowered fcst pops by accelerated the drying trend fm the nnw as shown by the latest HRRR model run. The new fcst still retains the categorical/hier likely pops over the s half or so of the cwa. The main reason this pcpn area wl not expand farther to the n and thus diminish faster is the axis of robust convection dvlpg fm scentral MN into central WI closer to h85 warm fnt/fgen axis/area of pwat aprchg 2 inches/sharper differential dvgc fm h85 thru h3/hier mucape aoa 2k j/kg is robbing mstr inflow into Upr MI and lowering the chc for deeper saturation over this area. && .SHORT TERM...(This evening through Thursday) Issued at 358 PM EDT WED SEP 21 2016 Dry air exists over the northern CWA where a SFC ridge extends. A SFC low over the central plains has an inverted trough extending NE across WI and lower MI, with an area of convection along the elevated portion of the warm front over a good portion of WI. Most do not initialize well with the current convection, and those poorly initializing models blow convection up across the SW CWA this evening as the warm front moves north and LLJ ramps up. If the front can move into the area with the LLJ, heavy rainfall would be a significant issue this evening and tonight as warm cloud depths would be over 11kft, PWATs near 1.75" and storm motion slow and nearly parallel to the front. Several inches of rain would be possible especially along the WI border. However, models that do initialize well (or at least better) with the WI convection (HRRR, HRRR-EXP, Canadian-Regional) keep heaviest precip will south of the area as the LLJ will be hindered north of that convection and the front may not even make it into the area. These models do bring precip into the area, just not the heaviest. Could still see 0.50- 1.00 inches right along the WI border. Thu should see overall diminishing precip chances, but isolate to scattered showers will continue to be possible through the day, especially over the south. The Keweenaw will see the lowest precip chances through tomorrow, possibly being dry much of the time. . .LONG TERM...(Thursday night through Wednesday) Issued at 445 PM EDT WED SEP 21 2016 An amplified pattern will prevail with a prominent mid/upper level ridge from the se CONUS through central Canada by this weekend and a trough slowly moving through the wrn CONUS. Although the models were in agreement with the development of a cutoff low over the cntrl CONUS there were large inconsistencies and run to run variations with the evolution and position of the low. So, uncertainty is higher than usual for this time frame with low forecast confidence. Thursday night into Friday, as the mid/upper level ridge builds to the west, sfc high pres over nrn Ontario will build to the south with drier air pushing into the nrn Great Lakes. This will push most of the pcpn south of the cwa. However, there still may be some light showers south central Thursday evening and far south overnight with weak bands of fgen to the north of the 850 mb front. Friday night and Saturday, the models were in better agreement that a stronger band of 700-500 mb fgen will develop in response to the amplifying ridge to the west and upper level div with the right entrance of the 250-300 mb jet to the northeast. This will support at least chance pops over most of the area by late fri night into sat morning. There is still some uncertainty with the impact of the antecedent dry airmass on the progression of the pcpn. Sunday through Wednesday, the developing blocking pattern will slow the advance of the pcpn associated with the strong moisture transport and forcing ahead of the plains trough with the highest pops mainly from sun night through mon. Even with the higher uncertainty with the cutoff low, shra chances are expected to linger through wed with the potential for the low lingering just to the west, per 12z GFS/GEFS/ECMWF. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 747 PM EDT WED SEP 21 2016 An area of showers will impact mainly IWD and SAW tngt. As the rain grdly moistens the initially dry llvls, expect VFR conditions this evng to deteriorate to IFR cigs at IWD and SAW late tngt toward sunrise. CMX wl remain under the influence of drier llvl air and very likely see fewer -shra and no worse than MVFR cigs. Not out of the question a TS could impact IWD this evng, but included no more than a VCTS group as the probability is not that hi per recent ltg trends. The arrival of some drier air wl end the showers and result in a grdl improvement in conditions on Thu. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 358 PM EDT WED SEP 21 2016 NE flow over Lake Superior with SFC trough moving into Upper MI and SFC ridge over Ontario could support some higher wind gusts to 25 knots over the western half of the lake into Thu and across the entire lake Thu night into Fri. As the Canadian high builds more over the Upper Lakes, winds will dip below 20 kts Friday night into Saturday night. Southerly winds will increase late Sunday into Mon to 25 to 30 knots over mainly the north central and eastern part of the lake as a low pressure trough approaches from the west. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ UPDATE...KC SHORT TERM...Titus LONG TERM...JLB AVIATION...KC MARINE...Titus
Area Forecast Discussion
National Weather Service Spokane WA
825 PM PDT Wed Sep 21 2016 .SYNOPSIS... Unsettled weather is expected late today through Thursday as a large area of low pressure slowly moves by the region. Look for breezy north winds at times. Thursday will be the coolest and dampest day of the week. Then by Friday and through the weekend, high pressure will arrive with less wind, warmer and dry weather. && .DISCUSSION... Update: The forecast has been updated to mainly lower POP`s into Thursday morning. Overall a bit of a complex weather situation through Thursday morning and have utilized satellite trends...latest HRRR runs...and the 18z/00z model guidance. Large closed low near Medford, Oregon this evening with a plume of moisture being drawn north ahead of it across extreme SE Washington, Idaho Panhandle, and western Montana. The latest model guidance keeps the deep moisture generally east of the area, clipping the Camas Prairie and Idaho Panhandle. A wave that is riding this moisture plume has generated scattered showers and even a few thunderstorms this evening near the Rathdrum and Bayview areas. This wave will continue to move north with increasing showers over the North Idaho Panhandle this evening. Water vapor shows drier air moving in behind this wave with satellite showing a large area of clearing from Colville to Davenport through the Upper Columbia Basin. The Cascades, Wenatchee area, and Okanogan Valley are staying west of this dry air and will continue to see isolated showers this evening. Overnight into Thursday morning another wave coming around the low moves north out of Oregon into SE Washington giving the Pullman and Lewiston areas as well as locations south of our area (Tri Cities) the best chance for rain showers. Further north latest models suggest more hit and miss showers and thus have lowered POP`s for much of North Central and NE Washington Thursday morning to chance instead of likely. JW && .AVIATION... 00Z TAFS: Scattered showers are expected this evening with rain showers likely for SE Washington and the Lewiston area Thursday morning. CIG`s are expected to lower, but confidence on the precise amount is low due to model differences with intensity and coverage of rain and consequent moistening of the boundary layer. Most TAF sites are expected to remain VFR...with a chance of MVFR conditions for KPUW 13z-19z. JW && .PRELIMINARY POINT TEMPS/POPS... Spokane 48 61 46 64 44 67 / 30 50 20 10 10 0 Coeur d`Alene 49 61 48 64 44 65 / 40 50 20 10 10 10 Pullman 47 56 44 62 42 65 / 40 60 30 10 10 10 Lewiston 52 62 51 69 50 70 / 50 60 40 10 10 10 Colville 45 64 42 69 40 70 / 40 50 10 10 10 0 Sandpoint 47 60 41 63 39 64 / 40 50 20 10 10 10 Kellogg 45 58 43 59 41 61 / 50 50 30 10 20 10 Moses Lake 49 67 43 70 43 72 / 20 30 10 10 10 0 Wenatchee 50 66 48 69 48 73 / 20 20 10 10 10 0 Omak 47 66 45 72 44 74 / 20 40 10 10 10 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
Area Forecast Discussion
National Weather Service Blacksburg VA
758 PM EDT Wed Sep 21 2016 .SYNOPSIS... An upper low will meander across the eastern Carolinas through Thursday before finally weakening and shifting offshore by the end of the week. High pressure will gradually build in from the west Friday into Saturday. A backdoor cold front drops south through the area late Saturday into Saturday night followed by cooler high pressure Sunday into early next week. && .NEAR TERM /THROUGH THURSDAY/... As of 245 PM EDT Wednesday... Closed low over the Southeast Coast will continue to interact with the Post tropical remnants of Julia during the period. As been the case for a couple of runs, the ECMWF and NAM remain slightly west of the GFS. One of the forecast challenges is the western edge of the moisture and the sharp gradient in showers. The HiResw-arw-east, wrf-arw-rnk, RAP and HRRR support the mention of isolated to scattered showers in southeast portions of forecast area this afternoon into tonight. The upper low remains fixed across the coastal Carolinas tonight into Thursday morning. believe that shower coverage may wrap tighter towards the coast tonight with drier air pushing into northwest portions of forecast area. Cloud cover tonight will vary from clear in the northwest to cloudy in the southeast. Lows tonight will range from the mid 50s in the northwest mountains to the mid 60s in the east. The closed upper low will slowly weaken and lift northeast on Thursday. The result of this transition will be even less coverage of isolated showers across the south and southeastern portion of the region. High temperatures Thursday will vary from the mid 70s in the mountains to the lower 80s in the Piedmont. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 230 PM EDT Wednesday... Persistent upper low will finally open up and shift northeast Thursday night in response to ridging nudging east from the Midwest. However may still be enough moisture around with the deformation axis on the back of the coastal system to produce a few added showers far southeast so left in an isolated mention early. Otherwise expecting a drier northerly flow to take shape under weak high pressure later Thursday night into early Saturday. This should bring clearing/sunny skies for late week into the weekend. However passing 500 mb trough well to the north by Saturday will propel a backdoor cold front toward the area Saturday afternoon and into parts of the region Saturday night. This a bit slower than previous given strong upper ridging overhead and warmth ahead of the front that should slow it down until Saturday night. Other than perhaps some developing post frontal low level cloudiness by late Saturday per the GFS, deep moisture to remain limited so not including any pops with the boundary for now. Given gradual 850 mb warming Friday and weak compression ahead of the front Saturday, looks like will return to above normal highs with mostly low/mid 80s both days with most surface based cool advection holding off until Saturday night at this point. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 130 PM EDT Wednesday... High amplitude blocky pattern looks to evolve later in the weekend into next week as potential cut off upper lows develop off New England and across the upper Midwest. This could basically sandwich the area within a sharp shortwave ridge axis between these two features pending exactly where the upper block develops. Differences between models continue in regards to strength of the upper systems and subsequent speed of surface features in this setup. However still appears will see a rather significant backdoor cold front drop south into the region by Saturday night/early Sunday before the boundary fades crossing into the Carolinas. Guidance still suggests some spotty shower potential Sunday with the front aloft nearby and developing onshore flow. Thus thinking more clouds and spotty shower pops Sunday and southern sections Sunday night with a shallow moisture axis lingering but iffy. Lots of uncertainty to take shape early next week as model spread remains large in just how fast a second cold front to the west will be able to slide east given eastern ridging in place. Latest 12Z GFS has continued to make a shift toward the slower ECMWF from overnight in keeping this slow moving front west of the mountains through midweek. However these solutions remain much slower and stronger than the GEFS which looks too weak/fast in lifting support out to to the north, while spilling the front quickly east. Overall the slower scenario would keep the area in more or less a more stable low level wedge formation per high pressure to the north under ridging aloft. Tendency in this setup likely to lead to more clouds and spotty showers/drizzle including much cooler temperatures into midweek. Therefore have trended in this direction with highs below Mos, but still mostly 70s and lows 50s- mid 60s, although highs by early week could be only in the 60s if more widespread low clouds do materialize. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 750 PM EDT Wednesday... Scattered to broken stratocumulus remained circulating around low pressure off the South Carolina coast. The western edge of the MVFR ceilings and light to moderate showers was east of a line from KFVX to KGSO. Medium confidence that the precipitation and lower ceilings will stay east of KLYH and KDAN through midnight. MVFR clouds will then spread west to the Blue Ridge, including at KROA, through sunrise. Otherwise a large cirrus shield covered much of Virginia and northern North Carolina this evening. High clouds will remain in place through Thursday. Have included LIFR fog in the western river valleys, including at KLWB. This will depend on the thinning and erosion of the high clouds. The more cloud cover, the less likely dense fog will develop. Any morning fog and low clouds will lift by mid morning, return all taf sites to VFR conditions by Thursday afternoon. GFS/HRRR and RAP guidance all keep a majority of any precipitation along and south of the Virginia/North Carolina border on Thursday. Extended aviation discussion... The slight chance of MVFR showers will remain just east of KLYH and KDAN through Thursday night. VFR conditions will prevail Thursday night outside of late night/early morning fog/low clouds. GFS/ECMWF have been consistent in filling and lifting out the low to the northeast on Friday. VFR conditions will prevail on Friday. A back-door cold front will come through the Mid-Atlantic region on Saturday. High pressure will build in for Sunday. The chance of precipitation or any sub VFR conditions will increase through the day Sunday and into Sunday night. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/RAB/WP NEAR TERM...KK SHORT TERM...JH LONG TERM...JH AVIATION...AMS/KK
Area Forecast Discussion
National Weather Service Billings MT
359 AM MDT Thu Sep 22 2016 .SHORT TERM...valid for Tdy and Fri... Damp 3 days ahead for the region as well above normal moisture content in the airmass will combine with a favorable upper level flow to produce bursts of moisture into the region. Timing continues to shift on the heaviest precipitation regarding this system and latest guidance is decreasing precipitation amounts today and Friday and shifting the emphasis to Friday night and Saturday for south central and southeast Montana. Expect persistent drizzle in a good portion of the region today as upslope flow continues and guidance shows saturated boundary layer moisture for most of the day. Expecting showers to move through the area in southerly flow aloft but this activity appears to be more hit or miss according to the latest HRRR. All models and HRRR hint at a broader outbreak of convective activity early this evening as a 700mb trowal rotates into the area around the upstream low over southern Idaho. Friday becomes complex as the upper low shifts towards the area and generates cyclogenesis over northern Wyoming but this looks to favor dry slotting for most of the area. There also may be a subtle downsloping role due to such strong southerly 700mb flow. Precipitation will increase Friday night as the low tracks into the area and becomes upslopish at the mid levels for the Beartooth and Absaroka Mountains with the best moisture spreading from there into the adjacent plains. Bottom line its a damp pattern and shower activity is going to have precipitation amounts be widely varied with the best windows for moisture this evening and Friday evening in the short term. borsum .LONG TERM...valid for Sat...Sun...Mon...Tue...Wed... Little in the way of changes for the extended forecast period...with bulk of the period under influence of upper level high pressure. There remains a bit of model uncertainty with the departure of the upper level low pressure system...but generally agree last remnant exiting to the east by Sunday evening. Models indicate a good chance for precip across the bulk of the region through the day Saturday...with best chances shifting eastward overnight. Made a few minor adjustments for timing...generally spreading likely pops back to the west for Saturday morning...with improved model agreement. Expect outdoor activities to be impacted from continued wet conditions. Expect mostly clear conditions across the bulk of the region for Sunday...as last remnants exit east through the afternoon/evening. Warming trend should begin Sunday...as temps climb back into the 60s. Models are in pretty good agreement on a blocking ridge of high pressure developing over the northeast CONUS by Sunday...which is then progged to shift eastward through the middle of the work week. Dry conditions should prevail...with a gradually warming into the low 70s by the end of the period. AAG && .AVIATION... Areas of rain...drizzle...and fog are occurring across western routes this morning. Flight conditions range from VLIFR in KBIL to MVFR in KSHR and KLVM. VFR conditions prevail over eastern routes...under partly cloudy skies this morning. Rain and drizzle...with lowering cigs...are expected to overspread all routes through today...with an isolated thunderstorm possible this afternoon. Mainly MVFR conditions are expected through the day in precip...but localized LIFR to VLIFR are possible in heavier precip and areas of fog this morning and later tonight. Area mountains will be mostly obscured through the period. AAG && .PRELIMINARY POINT TEMP/POPS... Tdy Fri Sat Sun Mon Tue Wed ------------------------------------------------------- BIL 063 051/058 047/056 044/063 042/065 044/068 046/071 8/T 95/R 66/W 31/B 01/U 11/U 11/U LVM 059 046/055 043/054 038/062 039/065 042/070 044/072 8/W 87/R 73/W 21/B 01/U 11/U 11/U HDN 069 051/062 047/056 043/064 040/064 043/067 045/070 6/T 95/R 66/W 31/B 01/U 11/U 11/U MLS 064 053/063 048/054 042/062 040/063 041/065 044/068 7/T 76/R 66/W 61/N 11/U 11/U 11/U 4BQ 066 053/070 048/056 041/061 037/061 039/065 042/070 4/T 74/R 56/W 41/B 11/U 11/U 11/U BHK 060 049/061 048/054 041/057 039/059 040/061 041/064 5/T 57/R 65/W 52/W 11/U 11/U 11/U SHR 070 052/065 045/054 041/060 039/062 040/066 042/070 7/T 85/R 66/W 31/B 11/U 11/U 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings
Area Forecast Discussion
National Weather Service Cheyenne WY
237 AM MDT THU SEP 22 2016 .SHORT TERM...(Today through Friday night) Issued at 215 AM MDT Thu Sep 22 2016 Obs show low clouds becoming more and more widespread for areas to the east of the Laramie Range as light northeasterly sfc winds transport llvl moisture into the area. Expecting cigs/vis to continue to lower through 12Z with widespread LIFR/IFR conditions. Extended fog all the way westward to the Laramie Range through mid morning. Temps will be about 10 degrees cooler across the plains, especially in the Nebraska Panhandle where low clouds will likely persist through the early aftn. Pressure falls will occur through the day over central WY with south-to-southeasterly winds becoming breezy by late aftn into the evening. With the best forcing remaining over the western half of WY, kept POPs mostly in the 20-40 percent range for areas along and west of the Laramie Range through the evening. The HRRR and NCAR ensemble is not showing much activity over the plains and especially the Nebraska Panhandle where the airmass will be mostly capped. Strong closed upper low is progged to move into southwest WY by Friday aftn with cooling aloft and upper level diffluence increasing for areas to the east of the Laramie Range. The models continue to be in good agreement at showing showers and isolated tstms developing over much of the plains of southeast WY into portions of the Nebraska Panhandle by the aftn and evening, in the convergence along the cold front. The cold frontal passage will occur through the evening with breezy west to southwest winds developing by late Friday night over southeast WY as the 700 mb CAG-CPR gradient rises to 40-50 meters. .LONG TERM...(Saturday through Wednesday) Issued at 215 AM MDT Thu Sep 22 2016 More Autumn like weather in store for the weekend as low pressure slowly moves through the area. Strong cold front associated with the low looks to move through Saturday morning. 700mb temperatures fall below freezing, down to -2C across the mountains to our west. Pretty good bet that the Snowy and Sierra Madre Ranges will see snow. Going to see an increase in winds as well Saturday as GFS 700mb winds at 55kts. 700mb Craig to Casper height gradient in excess of 60mtrs as well. If the low continues to track the way the GFS is forecasting, we could be looking at more winds than precip with this low. Cold and windy conditions continue Saturday night into Sunday with the upper low tracking into western North Dakota. 850mb winds in the panhandle 40-45kts, so wind headlines will probably be needed out that way, at least Advisory level if not warning. Freezing temperatures for lows Monday morning across much of the CWFA as skies clear out and winds ease. Looking at 20s for lows across southeast Wyoming and low 30s across the Panhandle. Start warming after Monday morning as 700mb temperatures climb back above freezing and upper ridge begins to build back into the area. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1101 PM MDT Wed Sep 21 2016 Stratus beginning to develop over northern Nebraska Panhandle and will move southwest into the Cheyenne area by 09Z. Could see low ceilings lasting most of the morning for our Nebraska Panhandle airports as well as KCYS. Generally followed latest HRRR guidance on timing of stratus onset and duration. && .FIRE WEATHER... Issued at 215 AM MDT Thu Sep 22 2016 No fire weather concerns through the end of the week. Temperatures will cool over the next few days, and especially after Friday evening behind a cold front. Minimum afternoon humidity values will mostly be above 30 percent. Along with an increase in cloud cover, there will be a chance of showers and thunderstorms through Friday, mostly during the afternoons and evenings. && .CYS Watches/Warnings/Advisories... WY...None. NE...None. && $$ SHORT TERM...ZF LONG TERM...GCC AVIATION...GCC FIRE WEATHER...ZF
Area Forecast Discussion
National Weather Service Duluth MN
320 AM CDT THU SEP 22 2016 .SHORT TERM...(Today through Friday) Issued at 320 AM CDT Thu Sep 22 2016 Surface high pressure over Saskatchewan/Manitoba will shift east into northern Ontario today into Friday, so the Northland`s dry northeast flow today will become easterly Friday. Expect generally seasonal weather. Today...An area of low pressure in the Central Plains had a trough/stationary front extending to northwest Wisconsin as of early this morning, and it could be the trigger for showers and some thunder today. However, the radar trends have been shifting the precipitation farther south, suggesting drier weather for the Northland. The dry RAP seems to be following the latest radar trends the best among the rest of the models, so leaned on the drier RAP. Now there only remains low chances of showers and thunder across parts of northwest Wisconsin. One feature the models have not captured has been the showers across the Arrowhead early this morning. These showers seem to be tied to a mid-level deformation band...which disappears later this morning. Highs today will be in the lower 60s. Tonight...There will be clearing tonight. Lows will range the lower 40s across northern Minnesota to the upper 40s and lower 50s across the southern forecast area. Friday`s highs will be in the lower 60s. .LONG TERM...(Friday night through Wednesday) Issued at 320 AM CDT Thu Sep 22 2016 Focus is on next low pressure system which will lift a warm front across the upper midwest Friday night into Saturday. This front and associated warm air advection is expected to be the focus for showers and a few thunderstorms. There will be a breif dry period late in the day saturday, as models suggest a dry slot pushes into the Northland. However, the break will be short lived as the cold front sweeps across the region, triggering another round of showers and thunderstorms Sunday. The rain chances will remain in the forecast into next week as a slow moving upper level low tracks across northern minnesota. The GFS bufr soundings show steep lapse rates associated with the low as 850 hPa temps fall into the single digits. Although timing differs with the gfs showing the slower trend, long range model suggest high pressure builds into the region for the later half of the week. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 320 AM CDT Thu Sep 22 2016 A stationary front will gradually slide southeastward from southern MN and central WI into northern IA and southern WI by Thursday evening. This will result in showers and storms impacting KHYR and potentially moving into KDLH/KBRD tonight. This will bring MVFR to IFR ceilings or lower as the lower levels moisten per the latest RAP/HRRR. In the heavier showers/storms expect visibility reduction, with visibility lowering most likely at KHYR. Kept in the MVFR range based on surrounding observations, but lower is possible. Will gradually see conditions improve to VFR at KDLH/KBRD/KHYR as the front slides away allowing drier air to move in from the northwest. Expect VFR conditions to develop late in the TAF period for KHYR and around 12Z to 15Z for KDLH/KBRD. && .PRELIMINARY POINT TEMPS/POPS... DLH 63 49 61 52 / 10 10 10 50 INL 64 42 65 50 / 0 0 0 50 BRD 67 52 64 56 / 10 10 20 40 HYR 64 52 64 54 / 40 10 10 40 ASX 62 51 63 52 / 20 10 0 40 && .DLH Watches/Warnings/Advisories... WI...None. MN...None. LS...Small Craft Advisory until midnight CDT Friday night for LSZ121- 141>148. && $$ SHORT TERM...Grochocinski LONG TERM...Graning AVIATION...WL
Area Forecast Discussion
National Weather Service Goodland KS
300 AM MDT THU SEP 22 2016 .SHORT TERM...(Today through Saturday night) Issued at 300 AM MDT Thu Sep 22 2016 Early morning RAP and satellite analysis show a large scale trough over the western US, with a closed center near the California/Oregon border. Ridging extends across the central US into the Northern Rockies, with SW flow over the intermountain West. Today-Tonight: A quasi-stationary front will remain either over the northern part of our CWA or just north of our CWA complicating temp forecast. WAA south of this feature should support highs in the 90s, while north highs may struggle to reach the low 80s (depending on cloud cover). Precip chances are minimal due to storm track to our west, and a very dry/stable in place over much of our CWA. There is a weak precip signal in high resolution guidance in our west associated with elevated instability above dry adiabatic layer. A few thunderstorms may develop and attempt to track northeast late this afternoon and evening with steepening lapse rates near the surface trough along the CO border ahead of front, but confidence is low. I introduced slight chances in eastern CO for now. Friday-Friday night: Large scale forcing increases with entrance region of jet ahead of large scale trough transitioning over our CWA. Dry line develops near the CO border and could act as focus for possible thunderstorm development early in the afternoon Friday before main period of forcing occurs Friday evening. Biggest question is going to be low level moisture along/east of this trough and impact on instability. NAM currently shows ML CAPE around 1500 J/KG which could be sufficient for an elevated risk of severe thunderstorms considering the very high shear values ahead of trough (50kt+ effective shear values). Based on soundings if favorable CAPE materializes we may see potential for thunderstorms to merge in a cluster or squall line with a potential for a widespread severe wind event. Severe hail may be a secondary threat at this point, unless we see better CAPE profiles than currently advertised. Other forecast issue of concern Friday would be potential for near critical fire weather conditions in eastern Colorado as windy conditions are expected (gusts 40-45 mph possible). There is enough spread on Tds between models but good mixing may support RH values dropping below 20 percent in our west (behind dry line). Will need to monitor. Saturday-Saturday night: Post frontal air mass with subsidence building from the northwest should preclude precip chances in all but our far east/southeast. Expect temperatures to return to near seasonal normals (highs around 80 and lows in the 40s to the lower 50s). .LONG TERM...(Sunday through Wednesday) Issued at 227 AM MDT Thu Sep 22 2016 The long term period is looking to be dry for the entire period. Yet, there are some major discrepancies between the GFS and EC. The current model run for the GFS has an exiting deep trough impacting the region through Tuesday night with a ridge building in behind it. The EC is much different, with the bulk of that trough moving out of the region Sunday and then developing a closed low off the trough over the southwestern states. That closed low is embedded under a ridge that is over the region. So as far as the models go, there is little confidence in which one will hold true at this point. One thing to mention is that Sunday and Monday nights could potentially see temperatures drop into the mid to upper 30s in some locations. Will keep an eye on this due to the possibility for a frost advisory. Otherwise, high temperatures are expected to be in the 60s and 70s through the entire period, which is about average or just under for this time of year. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1127 PM MDT Wed Sep 21 2016 Main aviation concern will be the possibility of low clouds and reduced visibility in fog overnight and into Thursday morning. A cold front will sag southward tonight and both are expected to develop in the post frontal low level upslope environment. Conditions will gradually improve through Thursday morning. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...CLT AVIATION...024
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
329 AM EDT Thu Sep 22 2016 .SYNOPSIS... A weak area of low pressure lingering along the coast of the Carolinas today will drift east on Friday. A broad upper ridge and surface high pressure will build over the region during the weekend as temperatures rise well above normal again. && .NEAR TERM /THROUGH TONIGHT/... As of 250 AM Thu: Still dealing with the effects of easterly flow around sfc/upper low over the Carolina coast. Pockets of light showers continue to move WSW from the Triangle to the Piedmont Triad, and while they thin out as they move into the drier air over our CWFA, they are beginning to make inroads. HRRR expects they will reach the Hwy 321 corridor before fizzling out around daybreak. A chance-range PoP is retained over the ern zones thru the morning. Thicker and lower cloud deck will also move in this morning, and guidance consensus indicates that will hang around well into the afternoon. Max temps are impacted, being just a couple degrees above normal across most of the area--the upper Savannah valley is expected to remain sunnier and still reach the upper 80s in spots. While some pockets of light stratiform rain will move through the Piedmont at times today, convection is expected to be a bit more widespread than yesterday, on account of slightly improved lapse rates. Meso models depict isolated convection over the Blue Ridge and parts of the lower Piedmont, similar to what verified yesterday, though with a little more QPF. Thunder is still too unlikely to mention. The low wobbles slightly northeast along the coast tonight, keeping the low level pattern pretty much the same. High pressure strengthens a bit over the Mid-Atlantic and down the southern Apps; this holds back the advance of clouds and precip, chances of which taper off overnight. Min temps across the area will be around 10 degrees above normal. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... As of 230 AM EDT Thursday...still expecting the weekend to be relatively benign weather-wise...although quite warm. The model guidance continues to show the old upper low opening up and filling along the Carolina coast on Friday, although at least some remnant of the upper system appears to be left to drift westward along the Gulf Coast, underneath the upper ridge, on Saturday. Whether or not this feature is the actual upper low should be immaterial, as the western Carolinas come under the influence of the amplifying upper ridge from Friday thru Saturday. The plume of wrap-around moisture might be sufficient to maintain a few showers over the eastern zones early in the day on Friday, but this will get pushed off to the east in the afternoon. Some instability over the SW mountains of NC might allow for a few showers over the higher terrain in the afternoon. Otherwise, expect most locations to remain dry with high temps climbing five degrees or so warmer than Thursday, back to almost Summer-like heat. That trend will continue into Saturday with only a few ridge-top showers able to break through a strong cap. High temps should be well above normal...and very much like summer. Uncertainty begins to creep in from the east on Sunday with some indication that surface high pressure moving across the Gt Lakes will impose an easterly flow that will bring some Atlantic moisture over the region. Fcst soundings from the GFS show the low level moisture allowing for more sfc-based buoyancy...enough to warrant a chance of precip over the mtns and foothills by afternoon. This seems reasonable enough to keep a small chance in the fcst. Temps may be held in check by increased cloud cover Sunday afternoon, at least over the NC part of the fcst area. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... As of 315 AM Thursday...you would find it difficult to remember a time in your recent memory when the operational runs of the medium range models had less run-to-run continuity and less agreement with the upper pattern as you see by the middle of next week. Whether the pattern will remain progressive or amplified or become blocked is difficult to determine right now, leading to much greater uncertainty than usual for this time of year. There is at least some agreement that at some point a frontal boundary will get strung out close to the fcst area in the middle or late part of the week, so there is hope of getting some much-needed rain. Details are very sketchy though. At this point, prefer to not make any changes in the medium range and will look toward hopefully seeing some consistency and/or trend in the next model cycle. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... At KCLT: Low pressure over the eastern Carolinas will sustain northeasterly flow over the field thru the period. MVFR to IFR stratus will expand westward thru central NC early this AM, along with bands of light showers. MOS guidance generally progs KCLT seeing IFR by daybreak, whereas raw models (including hi-res runs) generally favor low MVFR. The best performing guidance in this pattern has been raw, but with IFR under 100 SM away, I can`t deny the possibility. Hence TEMPO IFR for now; will refine this at 09z per latest guid/obs. The moist layer is deep enough that daytime improvement will be much slower than usual. Lapse rates are a tad more favorable than those Wed, so SCT SHRA are expected this aftn. Elsewhere: MVFR cigs are expected to advect over KHKY/KGSP/KGMU around dawn or a little later. KHKY has a small chance at IFR, with same reasoning as outlined for KCLT above. Some sprinkles are possible in the morning as bands of better forcing round the low. Also, once cigs finally lift and/or scatter a bit, there should be more coverage of aftn SHRA than the past couple days, though still too isolated to mention in TAFs. Winds mainly NE thru the period, with no restrictions anticipated tonight prior to 06z. Outlook: Meandering low pressure along the Carolina coast will persist thru Friday. This will allow isolated to scattered diurnal convection to continue especially east of I-77, and periodic chances for restrictive cigs. Meanwhile, a new cold front will be approaching from the northeast Sunday, but with sparse precipitation expected at this point. Confidence Table... 07-13Z 13-19Z 19-01Z 01-06Z KCLT High 91% High 97% High 97% High 100% KGSP High 99% High 88% High 100% High 100% KAVL High 84% High 94% High 100% High 100% KHKY High 98% High 89% High 100% High 100% KGMU High 100% High 88% High 100% High 100% KAND High 100% High 90% 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: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...PM NEAR TERM...Wimberley SHORT TERM...PM LONG TERM...PM AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Mobile AL
445 AM CDT THU SEP 22 2016 .NEAR TERM /Now Through Thursday night/...Surface high pressure ridge that has been over the region builds slightly today and tonight, resulting in a generally light and variable wind flow across the region (although becoming predominately southwesterly near shore late this afternoon with daytime heating developing a weak sea breeze circulation). In the upper levels 500mb low over the Carolina`s early this morning will likely open into a trof by tonight...with upper high pressure noted just to the west of the fcst area over eastern Texas and Louisiana. Models indicate that the resultant north to northeast flow aloft may allow weak shortwave energy to move south over or near western portions of fcst area today. With this...we could see some isolated afternoon showers or storms over the western zones (primarily from Mobile/Baldwin counties and points northward and westward). ECMWF advertises essentially no PoP today...while GFS shows very isolated. Even Hi-Res HRRR indicates very isolated coverages...so opted to not include a rain chance for today(although a very isolated shower or storm could be possible over the western zones as mentioned above). Expect temperatures to again heat up into the lower 90s over interior locations today (which is nearly 10 degrees above normal) and upper 80s to near 90 at the coast (also above normal...by 6-8 degrees for those locations). Low temperatures tonight expected to be above normal as well (by 5 to 10 degrees or so) ranging from upper 60s to near 70s inland to low to mid 70s at the coast. 12/DS .SHORT TERM /Friday Through Saturday night/...Several strong shortwaves swing slowly east over the western Conus to the Rockies, with a piece breaking off an forming a closed low over the Desert Southwest. More energy organizes into a deep upper low over the Canadian Maritimes through the same period, and in combination with the western trough, builds a strong upper ridge over the Mississippi River Valley. The opening upper system over the Carolina coast continues to weaken into a weak shortwave system, but remains strong enough to create a surface circulation strong enough to disrupt a surface ridge stretching south along the Appalachians into Saturday night. For the forecast, subsidence from the building upper trough will continue to keep temperatures will above seasonal levels (low to mid 90s for highs, upper 60s to low 70s for lows). With the surface ridge disrupted by a weak surface low/circulation, a diurnally driven daytime Gulf breeze/ night-time land breeze setup will create a few offshore shra/tsra, which will move inland with the Gulf breeze. As the Gulf breeze brings increasing moisture inland, am expecting precip chances to slowly creep up into the weekend. /16 .LONG TERM /Sunday Through Wednesday/...The extended continues to be a bear, with inconsistency between models and temporal inconsistencies. The latest medium range model runs are consistent in advertising a piece of energy breaking off the southern end the western upper trough, but the handling of the northern end is the where the problems lies. The GFS in now advertising the western trough working with the southward shifting Canadian upper low to build an upper trough over the Eastern Seaboard (like the ECMWF was advertising yesterday), whilst todays ECMWF run is advertising the northern piece of energy moving east over the Northern Plains/Great lakes region to the Mid Atlantic region. Even with the ECMWF advertising a flattening of the upper ridge, it is keeping it strong enough to advertise a warmer solution than the GFS. The difference is closer than yesterday, but is still significant enough to keep from saying they are in general agreement. Both are advertising a weak surface front being pushed towards the fa (from the nw by the GFS, from the n by the ECMWF), then stalling it close (ECMWF) or over (GFS) the fa by Wednesday evening. The GFS is also advertising a wetter solution then ECMWF, with the boundary stalled over the fa. Have went with a blended approach for the forecast, with temps remaining well above seasonal levels and chance of rain a bit above seasonal. /16 && .MARINE...A high pressure ridge will persist over and just north of the coastal waters through them remainder of the week and into the early part of next week. Winds will remain light (generally 10 knots or less) and sea states will remain small (occasionally 1 to 2 feet at the most...generally 1 foot or less). Only isolated to ocnly scattered showers and storms over the marine area. 12/DS && .PRELIMINARY POINT TEMPS/POPS... Mobile 92 71 93 71 / 10 0 20 10 Pensacola 90 74 91 73 / 10 0 20 10 Destin 89 77 90 75 / 10 0 20 10 Evergreen 92 70 93 69 / 10 0 10 0 Waynesboro 93 70 92 68 / 10 10 10 0 Camden 92 70 93 68 / 10 10 10 0 Crestview 93 69 95 68 / 10 0 10 10 && .MOB Watches/Warnings/Advisories... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob
Area Forecast Discussion
National Weather Service Phoenix AZ
250 AM MST THU SEP 22 2016 .SYNOPSIS... Showers and a few thunderstorms will be possible today along and ahead of a cold front moving through the region. This front will bring gusty winds, drier air, and slightly cooler temperatures for the remainder of the week. Breezy, but otherwise quiet weather will be the rule for the weekend and into early next week along with a warming trend. && .DISCUSSION... Impressive and unseasonably cool upper low continued to take shape along the northern California and Pacific NW coast early this morning, and latest guidance is consistent in calling for this low to progressively dive to the southeast today and push into the desert southwest bringing scattered to numerous showers along with embedded thunderstorms to the lower deserts during the day today. Ample moisture is already in place across the lower deserts; surface dewpoints at 2 am were mostly in the mid to upper 60s with values as high as low 70s across portions of the lower Colorado River valley. IR imagery showed variable amounts of low to mid cloud over the western AZ and southeast CA deserts although current radar showed little in terms of shower activity. Through about sunrise, QG forcing is not especially strong and local models do not really show much convection developing until around 12z or so this morning. As the main upper low center drops into central Nevada this afternoon, a well defined frontal band oriented mostly north to south will push across the western AZ deserts and into south central arizona; some of the best QG forcing/Q convergence fields move into the central deserts this afternoon and the associated UVV will act on a very moist airmass to generate widespread showers with embedded thunderstorm. Latest HRRR depicts this scenario very nicely and our forecast timing of the front will mirror the HRRR timing. POPs have been raised into the 50-60 percent ballpark across much of the central deserts with the best chances for rainfall in the greater Phoenix area to occur during the afternoon today. These higher POPs are supported by the latest NAEFS POPs guidance. Gusty west winds are expected to develop over the western deserts this afternoon behind the front, with the strongest winds likely to occur over favored areas of Imperial county; peak gusts to 35 mph are likely. There may be some patchy blowing dust occurring due to the wind, but recent rains in the area will limit the potential for any significant dust and as such we will not mention blowing dust in our forecast grids at this time. As far as temperatures go today, with thickness values lowering to around 576dm and with considerable lower clouds and showers in the area, high temperatures will fall to well below seasonal normal values with many lower AZ deserts falling into the upper 80s to low 90s. Phoenix should see a high around 90 today which would be 8 degrees below normal. Upper low center will quickly move east into Utah tonight and most of the strong QG forcing will shift well east of Phoenix; as such POPs tonight will focus across the higher terrain of southern Gila County with values as high as 40 percent or so. Rain chances will quickly diminish this evening over the south central deserts; rain chances in Phoenix will lower to around 10-15 percent after midnight. On Friday, the main upper low is forecast to quickly lift off to the northeast but a much drier and more subsident northwest flow aloft will overspread the deserts. Outside of a lingering slight chance of showers over southern Gila County we can expect generally sunny skies over the lower deserts with continued below seasonal normal high temperatures. PWAT values are forecast to fall to around one quarter of inch over much of the lower central deserts by Friday afternoon and the surface dewpoints in the Phoenix area will fall from the mid to upper 60s today into the upper teens to mid 20s. Over the weekend and into next week, dry conditions are forecast area wide with no threat of precipitation. A large upper ridge will initially amplify along the west coast giving a dry northerly flow to the area but early next week the ridge will flatten somewhat but continue giving dry northwest flow into the lower deserts. Expect generally sunny days and clear nights this weekend into the middle portion of next week along with a gradually warming trend. High temperatures will climb into the mid to upper 90s over most of the lower deserts by the early to middle part of next week. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: After little aviation impacts this evening, the potential for lower cigs and frontal rain bands will be the main aviation problem/challenge for Thursday. Cigs could drop to a 6K ft level as early as sunrise Thursday morning, with more likely filling and development though the morning hours. Confidence is good that a band of rain showers along with gusty SW winds and lower cigs 5-6K ft will pass through terminal sites Thursday afternoon before rapid improvement Thursday evening. Southeast California/Southwest Arizona including KIPL and KBLH: Aviation conditions will continue to improve overnight though cigs in a 8K-12K ft range should prevail through Thursday morning. The primary aviation problem will be gusty W/SW winds Thursday afternoon behind a cold front. Frequent gusts over 25kt will be likely, and brief periods of winds nearing 35kt are possible around and west of KIPL. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Friday through Tuesday... High pressure will move into the region and bring very dry air along with temperatures near or just below seasonable values. Minimum humidity values will drop into the teens all areas Saturday/Sunday, then show a slight upward trend into next week. Breezy winds can be expected Friday through Monday. Critical thresholds may be touched at times, especially across southeast California and the Lower Colorado River Valley. && .SPOTTER INFORMATION STATEMENT... Spotter reports may be needed locally Thursday afternoon across the Phoenix area. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...CB AVIATION...MO FIRE WEATHER...Iniguez
Area Forecast Discussion
National Weather Service Pueblo CO
1126 PM MDT WED SEP 21 2016 .SHORT TERM...(This evening through Thursday) Issued at 255 PM MDT Wed Sep 21 2016 ...A Warm and Breezy Thursday... Current water vapor imagery and upper air analysis is indicating moist southwest flow aloft across the state, as remnant moisture from tropical system Paine continues to lift out across the region. Water vapor imagery is also indicating drier air embedded within the flow across the Desert Southwest moving into western New Mexico and western Colorado, ahead of an upper trough digging across the West Coast at this time. Regional radars indicating isolated to scattered showers lifting north and east across the region, with a few thunderstorms across northwestern New Mexico at this time. Tonight and tomorrow...Latest models remain in fairly good agreement with southwest flow aloft slowly increasing across the region through the day tomorrow, as digging upper trough across the West Coast carves out an upper low across the Great Basin tomorrow afternoon. With that said, should continue to see showers with a few embedded thunderstorms moving across the area through the rest of the afternoon and into the early evening, with HRRR remaining consistent with the best coverage of storms being across the Pikes Peak region and the Raton Mesa region into Baca County. Showers and storms to diminish through the late evening, with loss of solar heating. However, could see some showers developing across the ContDvd and especially the southwest mountains, into early tomorrow morning, with increasing orographic flow. Overnight lows to be at or above seasonal average, especially across the eastern plains, where lee troughing will keep breezy southerly winds across the far se plains overnight. Will see more sun across the area early tomorrow, and with the increasing flow aloft and lee troughing across the plains, should see breezy southerly winds mixing across the area through the late morning and afternoon. Mid and upper level moisture slowly increases across the area again ahead of the Great Basin system, along with southerly low level winds across the plains keeping low level moisture in place, owning to another round of isolated to scattered afternoon showers and storms, with the best coverage over and near the higher terrain. Models continue to suggest near record high temperatures in the 80s to lower 90s across the plains for tomorrow, with highs in the 60s and 70s across the higher terrain and mainly 40s and 50s at the peaks. Current records for tomorrow are 85F at ALS...88F at COS and 93F at PUB. .LONG TERM...(Thursday night through Wednesday) Issued at 255 PM MDT Wed Sep 21 2016 ...Critical Fire Weather conditions I-25 corridor...Severe thunderstorm potential eastern plains...and snow possible higher mountains Friday... Western U.S. upper low will move across the Great Basin Thursday night before lifting northeastward into WY and MT Friday and Friday night. Deep southerly flow across the plains will advect 50 dewpoints northward into the southeast plains Thurs night into Friday morning. Initially will see some showers confined to the mountains Thurs night and Fri with snow levels down to around 12kft at times along the continental divide. Dry air moves in Friday afternoon as the trof axis moves across...which shallows out the moisture along the continental divide. By this time...westerly winds will be spreading eastward into the plains...sharpening up a dry line just east of the I-25 corridor. All areas will see gusty west to southwest winds west of the dry line...and gusty southerly winds to the east of the dry line. CAPE values could be up to around 1000 J/kg (according to the NAM12) with deep layer shears around 30-40 kts. This will lead to a potential for severe thunderstorms across the eastern counties including...Kiowa... Bent...Prowers and Baca. Severe wind gusts and large hail will be the primary storm threats. To the west...RHs dropping to around 15 percent...and the dry fuels will combine with gusty winds up to 40 mph to create the potential for critical fire weather conditions Friday afternoon and evening along the I-25 corridor. There are still some questions as to the position of the dry line and how low surface dew points will drop...however NAM12 seems too moist which is its bias...and have leaned grids towards the drier GFS and EC solutions for locations west of the dry line. For now have restricted the Fire Weather Watch to the southern I-25 corridor and a couple counties bordering to the east...but its possible that the watch may need to be expanded northward and eastward a bit more. Will let later shifts make any needed adjustments. As the trof axis lifts out to the north Friday night...should see drying conditions from west to east overnight. Any snowfall into the mountains looks brief and relatively light...with spotty amounts of an inch or two possible above 12kft. The San Luis Valley could see a fairly widespread hard freeze Friday night. While the main upper low lifts off to the northeast...more energy digging into the base of the trof across CO will keep generally unsettled weather over the region through the weekend. A cold front will drop through the region on Saturday with another surge of colder air for Saturday night. Models keep majority of precipitation across the southeast mountains and adjacent plains where H7 temperatures dropping to 0 to -2C could drive snow levels down to 9kft or a tad lower Sat night and again Sunday night. EC and GFS differ with QPF during these periods...with EC on the wetter side. Hard to say at this point how much snow will fall across the southeast mountains...but at this point a few inches of wet snow across the higher elevations look possible as GFS has trended back towards a wetter solution. Models shift the upper low eastward into the plains early next week...though differ with the track as GFS keeps the upper low center to the north across the Dakotas through Wed...while ECs track is farther south. Either way...CO is on the back side of the system with drier but cooler northerly flow. This will keep below normal temperatures across the region through the longer ranges. -KT && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1126 PM MDT Wed Sep 21 2016 VFR conditions expected to persist at COS, PUB and ALS over the next 24 hours. Mid and high level moisture streaming across the 4 Corners will continue intermittent cloud cover across all of the forecast area overnight. Isolated showers over the S Sangres will continue tonight into the early morning hrs. Otherwise, look for convection to fire up over the higher terrain by late morning, then isolated convection will spread across the TAF sites of KALS and KCOS through the aftn. Surface winds will persist out of the south. Moore && .PUB Watches/Warnings/Advisories... Fire Weather Watch from Friday afternoon through Friday evening for COZ227>232. && $$ SHORT TERM...MW LONG TERM...KT AVIATION...MOORE
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
323 AM CDT THU SEP 22 2016 .SHORT TERM...(Today and tonight) Issued at 319 AM CDT Thu Sep 22 2016 Current water vapor shows several weak mid level shortwaves moving out over the plains this morning. The associated weak isentropic lift is expected between now and late morning mainly over north central and far northern KS. This is where isolated to scattered showers and possibly some thunder may occur. The GFS seems quite bullish with the amount of QPF especially given the fact no other models agree with these amounts. Also, there is a small complex of decaying storms over southwest KS. Any remnant MCV could reach north central KS later this morning and bring a slight chance for showers as well. Only the HRRR is showing this activity will reach the forecast area. After late morning the chances should diminish. High clouds associated with the tropical moisture fetch will stick around until at least the evening. Highs today look to reach the upper 80s to lower 90s with dew points in the upper 60s. Winds will become gusty out of the south again today mainly during the late morning and early afternoon. Quiet weather continues tonight with partly cloudy skies and lows in the mid 60s. .LONG TERM...(Friday through Wednesday) Issued at 319 AM CDT Thu Sep 22 2016 Friday, the downstream ridge across the plains and mid MS river valley will amplify as the upper trough across the western US deepens. Friday will be another warm day with south-southeast winds of 15 to 25 MPH. Highs will reach the upper 80s to lower 90s. Thunderstorms that develop across western KS during the early evening hours may reach the western counties of the CWA late Friday night. Saturday through Sunday night, An intense upper level trough across the Western US on Friday will begin to shear apart as if moves east across the plains. There will be stronger ascent ahead of the positive tilt upper wave as it moves east across KS Saturday night through Sunday night. There will be a good transport of deep gulf moisture northeast across eastern KS at 850mb, ahead of the upper trough Saturday night through Sunday. Both the GFS and ECMWF forecast a widespread QPF of 1 to 3 inches across the CWA. If the rain falls over a 24 to 36 hour period then there will probably only be minor flooding possible. However, stronger thunderstorms may train from southwest to northeast across portions of the CWA Saturday evening into Sunday morning which may produce a greater potential for flash flooding. The next few shifts will have to watch the potential for flooding Saturday night into Sunday. Since the upper trough begins to shear apart as it moves into the plains, the 0-6 KM effective shear weakens during the afternoon hours. Given MLCAPES of 1500-2500 there could be a few pulse severe storms that develop along the surface front across west central KS, then may move into the western counties of the CWA before the stronger ascent moves east along the front and develops a line of showers and thunderstorms during the evening hours of Sunday. The GFS is more progressive moving the upper trough east across the plains and the heavier rain may move southeast of the CWA during the mid morning hours of Sunday. If the GFS were to verify the surface front will move southeast across the CWA during the early morning hours of Sunday and skies may clear from northwest to southeast during the afternoon hours. The ECMWF is slower moving the positive tilt H5 trough across the plains on Sunday and keeps widespread showers and elevated thunderstorms across much of the CWA through the day Sunday and into Sunday night as isentropic lift continues north of the surface cold front. Monday through Tuesday, Once again the ECMWF and GFS solutions diverge as the ECMWF continues to amplify the southern section of the upper level trough across southwest NM, then lifts the H5 trough northeast across the plains by mid week. The GFS keeps the northern branch of the H5 trough amplified as it shifts northeast across the Great Lake States. If the ECMWF verifies there will be at least a slight chances for showers and thunderstorms through the week. If the GFS were to verify then expect dry conditions through the week. Highs will be around 70 on Monday with temperatures warning into the mid to upper 70s by Thursday. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1154 PM CDT Wed Sep 21 2016 VFR conditions are likely through the TAF period with increased wind speeds during the late morning through afternoon hours. 2000 foot AGL winds will be in the 30-35 kt range through 12Z, which should be slightly less than LLWS criteria. && .TOP Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Sanders LONG TERM...Gargan AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Cheyenne WY
509 AM MDT THU SEP 22 2016 .SHORT TERM...(Today through Friday night) Issued at 215 AM MDT Thu Sep 22 2016 Obs show low clouds becoming more and more widespread for areas to the east of the Laramie Range as light northeasterly sfc winds transport llvl moisture into the area. Expecting cigs/vis to continue to lower through 12Z with widespread LIFR/IFR conditions. Extended fog all the way westward to the Laramie Range through mid morning. Temps will be about 10 degrees cooler across the plains, especially in the Nebraska Panhandle where low clouds will likely persist through the early aftn. Pressure falls will occur through the day over central WY with south-to-southeasterly winds becoming breezy by late aftn into the evening. With the best forcing remaining over the western half of WY, kept POPs mostly in the 20-40 percent range for areas along and west of the Laramie Range through the evening. The HRRR and NCAR ensemble is not showing much activity over the plains and especially the Nebraska Panhandle where the airmass will be mostly capped. Strong closed upper low is progged to move into southwest WY by Friday aftn with cooling aloft and upper level diffluence increasing for areas to the east of the Laramie Range. The models continue to be in good agreement at showing showers and isolated tstms developing over much of the plains of southeast WY into portions of the Nebraska Panhandle by the aftn and evening, in the convergence along the cold front. The cold frontal passage will occur through the evening with breezy west to southwest winds developing by late Friday night over southeast WY as the 700 mb CAG-CPR gradient rises to 40-50 meters. .LONG TERM...(Saturday through Wednesday) Issued at 215 AM MDT Thu Sep 22 2016 More Autumn like weather in store for the weekend as low pressure slowly moves through the area. Strong cold front associated with the low looks to move through Saturday morning. 700mb temperatures fall below freezing, down to -2C across the mountains to our west. Pretty good bet that the Snowy and Sierra Madre Ranges will see snow. Going to see an increase in winds as well Saturday as GFS 700mb winds at 55kts. 700mb Craig to Casper height gradient in excess of 60mtrs as well. If the low continues to track the way the GFS is forecasting, we could be looking at more winds than precip with this low. Cold and windy conditions continue Saturday night into Sunday with the upper low tracking into western North Dakota. 850mb winds in the panhandle 40-45kts, so wind headlines will probably be needed out that way, at least Advisory level if not warning. Freezing temperatures for lows Monday morning across much of the CWFA as skies clear out and winds ease. Looking at 20s for lows across southeast Wyoming and low 30s across the Panhandle. Start warming after Monday morning as 700mb temperatures climb back above freezing and upper ridge begins to build back into the area. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 507 AM MDT Thu Sep 22 2016 Followed latest HRRR guidance on the 12Z TAFs. Looks like stratus will stay in across the Nebraska Panhandle and KCYS through 18Z before breaking. Low clouds expected to return tonight, maybe a little earlier than when it formed this morning. && .FIRE WEATHER... Issued at 215 AM MDT Thu Sep 22 2016 No fire weather concerns through the end of the week. Temperatures will cool over the next few days, and especially after Friday evening behind a cold front. Minimum afternoon humidity values will mostly be above 30 percent. Along with an increase in cloud cover, there will be a chance of showers and thunderstorms through Friday, mostly during the afternoons and evenings. && .CYS Watches/Warnings/Advisories... WY...None. NE...None. && $$ SHORT TERM...ZF LONG TERM...GCC AVIATION...GCC FIRE WEATHER...ZF
Area Forecast Discussion
National Weather Service Duluth MN
652 AM CDT THU SEP 22 2016 .SHORT TERM...(Today through Friday) Issued at 320 AM CDT Thu Sep 22 2016 Surface high pressure over Saskatchewan/Manitoba will shift east into northern Ontario today into Friday, so the Northland`s dry northeast flow today will become easterly Friday. Expect generally seasonal weather. Today...An area of low pressure in the Central Plains had a trough/stationary front extending to northwest Wisconsin as of early this morning, and it could be the trigger for showers and some thunder today. However, the radar trends have been shifting the precipitation farther south, suggesting drier weather for the Northland. The dry RAP seems to be following the latest radar trends the best among the rest of the models, so leaned on the drier RAP. Now there only remains low chances of showers and thunder across parts of northwest Wisconsin. One feature the models have not captured has been the showers across the Arrowhead early this morning. These showers seem to be tied to a mid-level deformation band...which disappears later this morning. Highs today will be in the lower 60s. Tonight...There will be clearing tonight. Lows will range the lower 40s across northern Minnesota to the upper 40s and lower 50s across the southern forecast area. Friday`s highs will be in the lower 60s. .LONG TERM...(Friday night through Wednesday) Issued at 320 AM CDT Thu Sep 22 2016 Focus is on next low pressure system which will lift a warm front across the upper midwest Friday night into Saturday. This front and associated warm air advection is expected to be the focus for showers and a few thunderstorms. There will be a breif dry period late in the day saturday, as models suggest a dry slot pushes into the Northland. However, the break will be short lived as the cold front sweeps across the region, triggering another round of showers and thunderstorms Sunday. The rain chances will remain in the forecast into next week as a slow moving upper level low tracks across northern minnesota. The GFS bufr soundings show steep lapse rates associated with the low as 850 hPa temps fall into the single digits. Although timing differs with the gfs showing the slower trend, long range model suggest high pressure builds into the region for the later half of the week. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 639 AM CDT Thu Sep 22 2016 Low clouds and areas of drizzle will be common at Kbrd, kdlh and Khyr this morning. Conditions are expected to IMPROVE to vfr through the afternoon...then return to mvfr overnight as precipitation spreads northward back into the forecast area. The KINL terminal is expected to remain in the drier air today...remaining vfr through the taf period. The lowest conditiionswill be found at KBRD and KHYR. && .PRELIMINARY POINT TEMPS/POPS... DLH 63 49 61 52 / 10 10 10 50 INL 64 42 65 50 / 0 0 0 50 BRD 67 52 64 56 / 10 10 20 40 HYR 64 52 64 54 / 30 10 10 40 ASX 62 51 63 52 / 20 10 0 40 && .DLH Watches/Warnings/Advisories... WI...Beach Hazards Statement through this evening for WIZ001. MN...Beach Hazards Statement through this evening for MNZ037. LS...Small Craft Advisory until midnight CDT Friday night for LSZ121- 141>148. && $$ SHORT TERM...Grochocinski LONG TERM...Graning AVIATION...Graning
Area Forecast Discussion
National Weather Service Goodland KS
542 AM MDT THU SEP 22 2016 .SHORT TERM...(Today through Saturday night) Issued at 300 AM MDT Thu Sep 22 2016 Early morning RAP and satellite analysis show a large scale trough over the western US, with a closed center near the California/Oregon border. Ridging extends across the central US into the Northern Rockies, with SW flow over the intermountain West. Today-Tonight: A quasi-stationary front will remain either over the northern part of our CWA or just north of our CWA complicating temp forecast. WAA south of this feature should support highs in the 90s, while north highs may struggle to reach the low 80s (depending on cloud cover). Precip chances are minimal due to storm track to our west, and a very dry/stable in place over much of our CWA. There is a weak precip signal in high resolution guidance in our west associated with elevated instability above dry adiabatic layer. A few thunderstorms may develop and attempt to track northeast late this afternoon and evening with steepening lapse rates near the surface trough along the CO border ahead of front, but confidence is low. I introduced slight chances in eastern CO for now. Friday-Friday night: Large scale forcing increases with entrance region of jet ahead of large scale trough transitioning over our CWA. Dry line develops near the CO border and could act as focus for possible thunderstorm development early in the afternoon Friday before main period of forcing occurs Friday evening. Biggest question is going to be low level moisture along/east of this trough and impact on instability. NAM currently shows ML CAPE around 1500 J/KG which could be sufficient for an elevated risk of severe thunderstorms considering the very high shear values ahead of trough (50kt+ effective shear values). Based on soundings if favorable CAPE materializes we may see potential for thunderstorms to merge in a cluster or squall line with a potential for a widespread severe wind event. Severe hail may be a secondary threat at this point, unless we see better CAPE profiles than currently advertised. Other forecast issue of concern Friday would be potential for near critical fire weather conditions in eastern Colorado as windy conditions are expected (gusts 40-45 mph possible). There is enough spread on Tds between models but good mixing may support RH values dropping below 20 percent in our west (behind dry line). Will need to monitor. Saturday-Saturday night: Post frontal air mass with subsidence building from the northwest should preclude precip chances in all but our far east/southeast. Expect temperatures to return to near seasonal normals (highs around 80 and lows in the 40s to the lower 50s). .LONG TERM...(Sunday through Wednesday) Issued at 227 AM MDT Thu Sep 22 2016 The long term period is looking to be dry for the entire period. Yet, there are some major discrepancies between the GFS and EC. The current model run for the GFS has an exiting deep trough impacting the region through Tuesday night with a ridge building in behind it. The EC is much different, with the bulk of that trough moving out of the region Sunday and then developing a closed low off the trough over the southwestern states. That closed low is embedded under a ridge that is over the region. So as far as the models go, there is little confidence in which one will hold true at this point. One thing to mention is that Sunday and Monday nights could potentially see temperatures drop into the mid to upper 30s in some locations. Will keep an eye on this due to the possibility for a frost advisory. Otherwise, high temperatures are expected to be in the 60s and 70s through the entire period, which is about average or just under for this time of year. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 542 AM MDT Thu Sep 22 2016 Low stratus (already at KMCK) will continue to spread south towards KGLD, and fog should eventually spread towards both terminals. IFR CIGS are likely through about 16Z and IFR vis will be possible. Conditions should improve by late morning. A few high based showers or thunderstorms will be possible in the afternoon/evening mainly in eastern Colorado, and confidence is low that this activity would reach the vicinity of either KGLD or KMCK. Winds should shift to the south and increase around 00Z with low level wind shear likely at KMCK after 09Z. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...CLT AVIATION...DR
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1024 AM EDT Thu Sep 22 2016 .SYNOPSIS... A weak area of low pressure lingering along the coast of the Carolinas today will drift east on Friday. A broad upper ridge and surface high pressure will build over the region during the weekend as temperatures rise well above normal again. && .NEAR TERM /THROUGH TONIGHT/... As of 1020 AM EDT Thursday: Not much change needed/made to the fcst with this update as the region remains under the influence of the weak stacked low pressure system along the Carolina coast. As a result, moisture wrapping around the cyclonic flow continues to advect across the NC/SC piedmont leading to light dz/ra as well as low stratus. Thus, made a few tweaks to sky accounting for current stratus placement per visible sat, as well as a few adjustments to recent temperature trends. Did blend in the latest campop for pops, which didn`t really yield any sig changes. Previous Discussion: Still dealing with the effects of easterly flow around sfc/upper low over the Carolina coast. Pockets of light showers continue to spin across the Triad and into the NW Piedmont. Based on the consensus of recent HRRR runs, they may be able to push as far west as the Hwy 221 corridor by mid-morning. A thicker and lower cloud deck will also move in this morning, and guidance mostly indicates that will hang around well into the afternoon. Max temps are impacted, being just a couple degrees above normal across most of the area--the upper Savannah valley is expected to remain sunnier and still reach the upper 80s in spots. While some pockets of light stratiform rain will move through the Piedmont at times today, convection is expected to be a bit less isolated/infrequent than yesterday, on account of slightly improved lapse rates. Meso models depict isolated convection over the Blue Ridge and parts of the lower Piedmont, similar to what verified yesterday, though with a little more QPF. Thunder is still too unlikely to mention. The low wobbles slightly northeast along the coast tonight, keeping the low level pattern pretty much the same. 06z models trended cloudier for tonight, so with this update I raised sky cover a bit, but still think there will be a decent gradient across the area. Min temps will be around 10 degrees above normal. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... As of 230 AM EDT Thursday...still expecting the weekend to be relatively benign weather-wise...although quite warm. The model guidance continues to show the old upper low opening up and filling along the Carolina coast on Friday, although at least some remnant of the upper system appears to be left to drift westward along the Gulf Coast, underneath the upper ridge, on Saturday. Whether or not this feature is the actual upper low should be immaterial, as the western Carolinas come under the influence of the amplifying upper ridge from Friday thru Saturday. The plume of wrap-around moisture might be sufficient to maintain a few showers over the eastern zones early in the day on Friday, but this will get pushed off to the east in the afternoon. Some instability over the SW mountains of NC might allow for a few showers over the higher terrain in the afternoon. Otherwise, expect most locations to remain dry with high temps climbing five degrees or so warmer than Thursday, back to almost Summer-like heat. That trend will continue into Saturday with only a few ridge-top showers able to break through a strong cap. High temps should be well above normal...and very much like summer. Uncertainty begins to creep in from the east on Sunday with some indication that surface high pressure moving across the Gt Lakes will impose an easterly flow that will bring some Atlantic moisture over the region. Fcst soundings from the GFS show the low level moisture allowing for more sfc-based buoyancy...enough to warrant a chance of precip over the mtns and foothills by afternoon. This seems reasonable enough to keep a small chance in the fcst. Temps may be held in check by increased cloud cover Sunday afternoon, at least over the NC part of the fcst area. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... As of 315 AM Thursday...you would find it difficult to remember a time in your recent memory when the operational runs of the medium range models had less run-to-run continuity and less agreement with the upper pattern as you see by the middle of next week. Whether the pattern will remain progressive or amplified or become blocked is difficult to determine right now, leading to much greater uncertainty than usual for this time of year. There is at least some agreement that at some point a frontal boundary will get strung out close to the fcst area in the middle or late part of the week, so there is hope of getting some much-needed rain. Details are very sketchy though. At this point, prefer to not make any changes in the medium range and will look toward hopefully seeing some consistency and/or trend in the next model cycle. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... At KCLT: Low pressure over the eastern Carolinas will sustain a breezy northeasterly flow over the field thru the period. MVFR stratus will expand westward thru central NC in the first few hrs of the period, along with bands of light showers. Can`t absolutely rule out IFR early on, but it is unlikely given how slowly it advanced in the predawn hours. The moist layer is deep enough that daytime improvement will be much slower than usual. Lapse rates are a tad more favorable than those Wed, so a few SHRA may be around during the afternoon; chance is too low to mention at this issuance. Tonight, with the pattern having changed very little, MVFR cigs again are likely to expand over the field after midnight. Elsewhere: MVFR cigs are expected to expand as far west as KHKY/KGSP before that deck begins to dissipate. Abundant low VFR cloud is expected to hang around into afternoon, however. Some sprinkles are possible in the morning as bands of better forcing round the low. Also, once cigs finally lift and/or scatter a bit, a few diurnally driven SHRA may develop, though still too isolated to mention in TAFs. Winds mainly NE thru the period, with some low-end gusts in the middle of the day. MVFR cigs are expected to advect in from the east again overnight tonight, similar to how they did so early today. Profiles look a bit more favorable for valley fog, too, so a vsby restriction is introduced at KAVL. Outlook: Meandering low pressure along the Carolina coast will persist thru Friday. This will allow isolated to scattered diurnal convection to continue especially east of I-77, and periodic chances for restrictive cigs. Meanwhile, a new cold front will be approaching from the northeast Sunday, but with sparse precipitation expected at this point. Confidence Table... 14-20Z 20-02Z 02-08Z 08-12Z KCLT High 96% High 94% High 100% High 97% KGSP High 87% High 100% High 100% High 100% KAVL High 100% High 100% High 100% Med 77% KHKY High 98% High 100% High 100% Med 71% 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: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...PM NEAR TERM...CDG/Wimberley SHORT TERM...PM LONG TERM...PM AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Melbourne FL
950 AM EDT THU SEP 22 2016 .UPDATE... Surface/satellite observations continue to indicate a broad and diffuse surface trough extending from a weak low pressure area and its attendant frontal boundary along the GA/SC/NC coast to just east of central Florida. Water vapor and RAP analysis fields show the mid and upper level trough near and west of this feature elongating to the SW due to deformation being imposed by strong ridges to its west and east. Morning RAOB data shows local air mass has dried out a little, with mean PWATs in the 1.7"/1.8" range at JAX/TBW/XMR and around 1.9" at MFL. H50 temps are averaging a tepid -6C. Both the RAOBs and CCAFS 915MHZ DRWP data show very light SW flow throughout the column, averaging about 6-8KT, except for a small layer of 11-14KT winds between H80 and H50. Setup of weak steering and seasonable PWAT values portends a rather nondescript convective day, with local sea, lake and t-storm outflow boundaries dominant. Lightning and ponding from locally heavy downpours the main concerns with todays storms. Maybe a slightly better chance for storms down near Lake Okeechobee owing to slightly higher PWAT and sea/lake breeze interaction. See no compelling reason to adjust the inherited forecast of 20-30 pct. && .AVIATION...VFR to start, with ISOLD-SCT diurnal SHRA/TS increasing in coverage starting about 17Z-18Z. for better or worse, tweaked the 12Z TAFs to confine VCTS south of LEE-SFB-DAB. POPs in the 20-30 pct range didn`t warrant TEMPO groups, however best chance for TS INVOF MLB-SUA corridor looks to be 17-21Z, and 20Z-24Z for ISM-MCO VCNTY. && .MARINE...Light offshore component to wind flow will yield to diurnal sea breeze circulation during the afternoon, with a small chance for offshore moving storms late in the day, mainly near the coast. Seas 1.5 - 2.0FT near shore and 2.0 - 2.5FT well offshore. Given current conditions, plan to shave about half a foot from the grids. && FORECAST UPDATE...Cristaldi IMPACT WX/RADAR...Glitto && .PREV DISCUSSION... /issued 335 AM EDT Thu Sep 22 2016/ Fri-Fri night...Weakening shortwave troughing along the eastern seaboard continues to do so over this period. In turn, shortwave ridging amplifies from the northwest Gulf through the Eastern Plains and Upper Midwest. At the surface, weak high pressure encompasses much of the Gulf Coast States with a very weak pressure gradient across ECFL. Light/variable morning winds will become onshore in the afternoon as the east coast sea breeze develops and pushes slowly inland. Greater deep layer moisture will be confined to the Treasure Coast (PWAT greater than 2 inches), while PWAT values to the north across the I-4 corridor will flirt with only 1.50 inches. Will keep 30 percent POPs across the I-4 corridor, which may be generous, and 40 to 50 percent POPs southward toward the Treasure Coast. The storm steering flow will remain fairly light at 5 to 10 mph out of the southwest. A few afternoon/early evening storms may move off of the east coast south from the Cape. Winds will become light/variable again in the evening/overnight. Highs in the U80s to near 90 degrees near the east coast and generally L90s into the interior. Overnight conditions remain warm/humid with lows in the L-M70s. Sat-Wed...Shortwave ridging aloft remains forecast to build across the eastern CONUS this weekend, continuing to amplify to the east of the Ohio/Tennessee Valleys Mon-Tue, then getting nudged off of the Atlantic seaboard Tue night/Wed as a fairly strong upper-level trough plows through much of the central CONUS and upper Midwest. The pressure gradient will remain very weak with light/variable winds overnight/early morning becoming onshore each afternoon as the east coast sea breeze develops and pushes inland. Deep layer moisture values increase areawide through the period, promoting 40 to 50 percent chances of afternoon and early evening showers/storms. Storm motion will remain out of the west or southwest, albeit light, into Mon then will become easterly Tue/Wed as onshore flow deepens over the area. Main storm threats will remain heavy downpours, lightning, and some brief gusty winds. Expect some long period swells to impact the east coast beaches and possibly bringing a higher rip current risk by Friday and into the weekend. Highs/lows near to slightly above normal through the extended. && .AVIATION...Lingering isolated showers/storms produced local IFR- MVFR during the overnight from KMLB-KSUA, but a diminishing trend is underway and most terminals will be VFR this morning. The highest chance for afternoon/evening storms looks to be southward from KMCO-KTIX. && .MARINE... Today-Tonight...Generally favorable boating conditions continuing, though mariners will need to keep aware of isolated to scattered showers/storms that form over land this afternoon/evening and push slowly back to the coast. Otherwise, a weak pressure gradient in place will yield light/variable morning winds, which become onshore by early afternoon as the sea breeze forms. Light winds again in the evening, gradually becoming offshore after midnight. The Wave Watch model looks slightly better than the local wave model, though seas will be rather benign with swells 2 feet nearshore and 3 feet offshore. Fri-Mon...A weak pressure gradient will continue over the local coastal waters promoting a gentle to light breeze. TC Karl will re- curve away from the area, sending a small-moderate swell into the local waters. Seas generally 2-3FT near shore and 4FT (or a little higher) over the open Atlantic, decreasing by Monday as the local swell generated by Karl decays. Isolated to scattered lightning storms will continue in the forecast. && .PRELIMINARY POINT TEMPS/POPS... DAB 88 73 88 72 / 20 20 30 20 MCO 91 74 92 73 / 30 20 30 20 MLB 89 75 90 74 / 40 30 30 30 VRB 89 75 89 72 / 40 30 40 30 LEE 91 74 91 74 / 20 20 30 20 SFB 91 74 91 74 / 20 20 30 20 ORL 91 75 92 75 / 30 20 30 20 FPR 90 74 90 72 / 40 30 40 30 && .MLB Watches/Warnings/Advisories... FL...None. AM...None. && $$
Area Forecast Discussion
National Weather Service Mobile AL
651 AM CDT THU SEP 22 2016 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION... 22/12Z issuance...VFR conditions will continue through the forecast period. Some isolated showers or storms from Mobile Bay area northward and westward this afternoon with brief periods of MVFR possible...but overall coverage is expected to be very sparse and only included VCTS at terminals. Surface winds light and variable for most locations...with brief period of more predominant southeast winds near the coast this afternoon. 12/DS && .PREV DISCUSSION... /issued 445 AM CDT THU SEP 22 2016/ NEAR TERM /Now Through Thursday night/...Surface high pressure ridge that has been over the region builds slightly today and tonight, resulting in a generally light and variable wind flow across the region (although becoming predominately southwesterly near shore late this afternoon with daytime heating developing a weak sea breeze circulation). In the upper levels 500mb low over the Carolina`s early this morning will likely open into a trof by tonight...with upper high pressure noted just to the west of the fcst area over eastern Texas and Louisiana. Models indicate that the resultant north to northeast flow aloft may allow weak shortwave energy to move south over or near western portions of fcst area today. With this...we could see some isolated afternoon showers or storms over the western zones (primarily from Mobile/Baldwin counties and points northward and westward). ECMWF advertises essentially no PoP today...while GFS shows very isolated. Even Hi-Res HRRR indicates very isolated coverages...so opted to not include a rain chance for today(although a very isolated shower or storm could be possible over the western zones as mentioned above). Expect temperatures to again heat up into the lower 90s over interior locations today (which is nearly 10 degrees above normal) and upper 80s to near 90 at the coast (also above normal...by 6-8 degrees for those locations). Low temperatures tonight expected to be above normal as well (by 5 to 10 degrees or so) ranging from upper 60s to near 70s inland to low to mid 70s at the coast. 12/DS SHORT TERM /Friday Through Saturday night/...Several strong shortwaves swing slowly east over the western Conus to the Rockies, with a piece breaking off an forming a closed low over the Desert Southwest. More energy organizes into a deep upper low over the Canadian Maritimes through the same period, and in combination with the western trough, builds a strong upper ridge over the Mississippi River Valley. The opening upper system over the Carolina coast continues to weaken into a weak shortwave system, but remains strong enough to create a surface circulation strong enough to disrupt a surface ridge stretching south along the Appalachians into Saturday night. For the forecast, subsidence from the building upper trough will continue to keep temperatures will above seasonal levels (low to mid 90s for highs, upper 60s to low 70s for lows). With the surface ridge disrupted by a weak surface low/circulation, a diurnally driven daytime Gulf breeze/ night-time land breeze setup will create a few offshore shra/tsra, which will move inland with the Gulf breeze. As the Gulf breeze brings increasing moisture inland, am expecting precip chances to slowly creep up into the weekend. /16 LONG TERM /Sunday Through Wednesday/...The extended continues to be a bear, with inconsistency between models and temporal inconsistencies. The latest medium range model runs are consistent in advertising a piece of energy breaking off the southern end the western upper trough, but the handling of the northern end is the where the problems lies. The GFS in now advertising the western trough working with the southward shifting Canadian upper low to build an upper trough over the Eastern Seaboard (like the ECMWF was advertising yesterday), whilst todays ECMWF run is advertising the northern piece of energy moving east over the Northern Plains/Great lakes region to the Mid Atlantic region. Even with the ECMWF advertising a flattening of the upper ridge, it is keeping it strong enough to advertise a warmer solution than the GFS. The difference is closer than yesterday, but is still significant enough to keep from saying they are in general agreement. Both are advertising a weak surface front being pushed towards the fa (from the nw by the GFS, from the n by the ECMWF), then stalling it close (ECMWF) or over (GFS) the fa by Wednesday evening. The GFS is also advertising a wetter solution then ECMWF, with the boundary stalled over the fa. Have went with a blended approach for the forecast, with temps remaining well above seasonal levels and chance of rain a bit above seasonal. /16 MARINE...A high pressure ridge will persist over and just north of the coastal waters through them remainder of the week and into the early part of next week. Winds will remain light (generally 10 knots or less) and sea states will remain small (occasionally 1 to 2 feet at the most...generally 1 foot or less). Only isolated to ocnly scattered showers and storms over the marine area. 12/DS && .MOB Watches/Warnings/Advisories... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob
Area Forecast Discussion
National Weather Service Phoenix AZ
618 AM MST THU SEP 22 2016 .UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS. && .SYNOPSIS... Showers and a few thunderstorms will be possible today along and ahead of a cold front moving through the region. This front will bring gusty winds, drier air, and slightly cooler temperatures for the remainder of the week. Breezy, but otherwise quiet weather will be the rule for the weekend and into early next week along with a warming trend. && .DISCUSSION... Impressive and unseasonably cool upper low continued to take shape along the northern California and Pacific NW coast early this morning, and latest guidance is consistent in calling for this low to progressively dive to the southeast today and push into the desert southwest bringing scattered to numerous showers along with embedded thunderstorms to the lower deserts during the day today. Ample moisture is already in place across the lower deserts; surface dewpoints at 2 am were mostly in the mid to upper 60s with values as high as low 70s across portions of the lower Colorado River valley. IR imagery showed variable amounts of low to mid cloud over the western AZ and southeast CA deserts although current radar showed little in terms of shower activity. Through about sunrise, QG forcing is not especially strong and local models do not really show much convection developing until around 12z or so this morning. As the main upper low center drops into central Nevada this afternoon, a well defined frontal band oriented mostly north to south will push across the western AZ deserts and into south central arizona; some of the best QG forcing/Q convergence fields move into the central deserts this afternoon and the associated UVV will act on a very moist airmass to generate widespread showers with embedded thunderstorm. Latest HRRR depicts this scenario very nicely and our forecast timing of the front will mirror the HRRR timing. POPs have been raised into the 50-60 percent ballpark across much of the central deserts with the best chances for rainfall in the greater Phoenix area to occur during the afternoon today. These higher POPs are supported by the latest NAEFS POPs guidance. Gusty west winds are expected to develop over the western deserts this afternoon behind the front, with the strongest winds likely to occur over favored areas of Imperial county; peak gusts to 35 mph are likely. There may be some patchy blowing dust occurring due to the wind, but recent rains in the area will limit the potential for any significant dust and as such we will not mention blowing dust in our forecast grids at this time. As far as temperatures go today, with thickness values lowering to around 576dm and with considerable lower clouds and showers in the area, high temperatures will fall to well below seasonal normal values with many lower AZ deserts falling into the upper 80s to low 90s. Phoenix should see a high around 90 today which would be 8 degrees below normal. Upper low center will quickly move east into Utah tonight and most of the strong QG forcing will shift well east of Phoenix; as such POPs tonight will focus across the higher terrain of southern Gila County with values as high as 40 percent or so. Rain chances will quickly diminish this evening over the south central deserts; rain chances in Phoenix will lower to around 10-15 percent after midnight. On Friday, the main upper low is forecast to quickly lift off to the northeast but a much drier and more subsident northwest flow aloft will overspread the deserts. Outside of a lingering slight chance of showers over southern Gila County we can expect generally sunny skies over the lower deserts with continued below seasonal normal high temperatures. PWAT values are forecast to fall to around one quarter of inch over much of the lower central deserts by Friday afternoon and the surface dewpoints in the Phoenix area will fall from the mid to upper 60s today into the upper teens to mid 20s. Over the weekend and into next week, dry conditions are forecast area wide with no threat of precipitation. A large upper ridge will initially amplify along the west coast giving a dry northerly flow to the area but early next week the ridge will flatten somewhat but continue giving dry northwest flow into the lower deserts. Expect generally sunny days and clear nights this weekend into the middle portion of next week along with a gradually warming trend. High temperatures will climb into the mid to upper 90s over most of the lower deserts by the early to middle part of next week. && .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: A cold front will approach from the west, crossing through the terminals from mid to late afternoon along with rain showers and isolated thunderstorms likely beginning about 22Z. Expect low cloud cigs from 5-6Kft. for most of the day before skies begin to scatter beginning in the the late afternoon and early evening. Light winds in the morning should become breezy and southerly by late morning, and then southwesterly to westerly with gusts of 17-22kts. beginning in the early afternoon. Westerly winds will begin to taper off to 7-10 kts. beginning in the early evening. Southeast California/Southwest Arizona including KIPL and KBLH: Clear to partly cloudy skies with few to sct low clouds near 6-7 Kft. will become clear by late morning at both sites. Breezy westerly winds at KIPL will become windy by late morning with gusts of 21-30kts. Meanwhile windy southwesterly winds will develop at KBLH by late morning with gusts of 25-28kts. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Saturday through Wednesday... Very dry northwesterly flow aloft behind a trough to the east on Saturday will eventually be replaced by a dry ridge of high pressure on Wednesday along with below normal high temperatures throughout the period. Breezy to occasionally windy northerly component winds will prevail out west, especially along the lower Colorado river valley each afternoon through Monday with gusts of 20 to 28 mph, although conditions are not expected to reach critical thresholds at this time. Gusty northeasterly winds will then spread into the lower deserts and the higher terrain of southern Gila county beginning Tuesday. Minimum RH of 13 to 20 percent on Saturday will slowly increase each day until reaching only 20 to 30 percent on Wednesday. Fair overnight recoveries on Saturday will improve to fair to good by Tuesday. && .SPOTTER INFORMATION STATEMENT... Spotter reports may be needed locally Thursday afternoon across the Phoenix area. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...CB AVIATION...Sawtelle FIRE WEATHER...Sawtelle
...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight) Issued at 319 AM CDT Thu Sep 22 2016 Current water vapor shows several weak mid level shortwaves moving out over the plains this morning. The associated weak isentropic lift is expected between now and late morning mainly over north central and far northern KS. This is where isolated to scattered showers and possibly some thunder may occur. The GFS seems quite bullish with the amount of QPF especially given the fact no other models agree with these amounts. Also, there is a small complex of decaying storms over southwest KS. Any remnant MCV could reach north central KS later this morning and bring a slight chance for showers as well. Only the HRRR is showing this activity will reach the forecast area. After late morning the chances should diminish. High clouds associated with the tropical moisture fetch will stick around until at least the evening. Highs today look to reach the upper 80s to lower 90s with dew points in the upper 60s. Winds will become gusty out of the south again today mainly during the late morning and early afternoon. Quiet weather continues tonight with partly cloudy skies and lows in the mid 60s. .LONG TERM...(Friday through Wednesday) Issued at 319 AM CDT Thu Sep 22 2016 Friday, the downstream ridge across the plains and mid MS river valley will amplify as the upper trough across the western US deepens. Friday will be another warm day with south-southeast winds of 15 to 25 MPH. Highs will reach the upper 80s to lower 90s. Thunderstorms that develop across western KS during the early evening hours may reach the western counties of the CWA late Friday night. Saturday through Sunday night, An intense upper level trough across the Western US on Friday will begin to shear apart as if moves east across the plains. There will be stronger ascent ahead of the positive tilt upper wave as it moves east across KS Saturday night through Sunday night. There will be a good transport of deep gulf moisture northeast across eastern KS at 850mb, ahead of the upper trough Saturday night through Sunday. Both the GFS and ECMWF forecast a widespread QPF of 1 to 3 inches across the CWA. If the rain falls over a 24 to 36 hour period then there will probably only be minor flooding possible. However, stronger thunderstorms may train from southwest to northeast across portions of the CWA Saturday evening into Sunday morning which may produce a greater potential for flash flooding. The next few shifts will have to watch the potential for flooding Saturday night into Sunday. Since the upper trough begins to shear apart as it moves into the plains, the 0-6 KM effective shear weakens during the afternoon hours. Given MLCAPES of 1500-2500 there could be a few pulse severe storms that develop along the surface front across west central KS, then may move into the western counties of the CWA before the stronger ascent moves east along the front and develops a line of showers and thunderstorms during the evening hours of Sunday. The GFS is more progressive moving the upper trough east across the plains and the heavier rain may move southeast of the CWA during the mid morning hours of Sunday. If the GFS were to verify the surface front will move southeast across the CWA during the early morning hours of Sunday and skies may clear from northwest to southeast during the afternoon hours. The ECMWF is slower moving the positive tilt H5 trough across the plains on Sunday and keeps widespread showers and elevated thunderstorms across much of the CWA through the day Sunday and into Sunday night as isentropic lift continues north of the surface cold front. Monday through Tuesday, Once again the ECMWF and GFS solutions diverge as the ECMWF continues to amplify the southern section of the upper level trough across southwest NM, then lifts the H5 trough northeast across the plains by mid week. The GFS keeps the northern branch of the H5 trough amplified as it shifts northeast across the Great Lake States. If the ECMWF verifies there will be at least a slight chances for showers and thunderstorms through the week. If the GFS were to verify then expect dry conditions through the week. Highs will be around 70 on Monday with temperatures warning into the mid to upper 70s by Thursday. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 609 AM CDT Thu Sep 22 2016 VFR conditions expected through the taf period. && .TOP Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Sanders LONG TERM...Gargan AVIATION...Sanders
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
338 PM CDT Thu Sep 22 2016 .SHORT TERM.../This evening through Friday/ Issued at 307 PM CDT Thu Sep 22 2016 The situation is still conducive for heavy rains tonight but hopefully not to the same extent as yesterday. Water vapor imagery does not show the moisture fetch to the same degree as was shown Wednesday, but there is a decided back edge to the vertical motion passing through the Plains into western KS/NE which should aid lift into the night. This has resulted in weak but broad mid level kinematic forcing with a ribbon of somewhat favorable mid level temp and theta-e lapse rates from KS into IA. Thermodynamically the forcing is somewhat better with 850/700mb warm advection noted into IA and 0-2km moisture pooling into our baroclinic zone as well. 20Z surface analysis shows at least two boundaries, one tied into low pressure near Lincoln between Red Oak and Atlantic, another farther northeast through the Des Moines metro area more associated with previous MCS outflow and likely another from Estherville to Grinnell with seems to be immediately associated with the weak MCS. This will provide for ample isentropic lift into the night, but the flow is weaker along the 305K inflow surface vs last night, down to 15- 30kts. RAP elevated instability layers suggest elevated CAPEs will reach uncapped 1500 j/kg later tonight sustaining additional MCS development. There could be a few strong to severe storms, but overall the Marginal Risk seems fine due to reduced effective shear. .LONG TERM.../Friday night through Thursday/ Issued at 307 PM CDT Thu Sep 22 2016 Expecting some early morning ongoing convection across the eastern and northeastern areas to end by mid to late morning. Warm front will finally retreat north into the afternoon hours with rather warm and humid conditions across the area for the remainder of the day. Some cloud cover extending across the northeast with light showers then will give way to some sun in the afternoon. As has been advertised...highs will warm into the upper 80s to lower 90s over the south with the upper 70s in the far north by late day Friday. No rainfall is expected until the long wave trough approaches Saturday morning with showers and thunderstorms moving into Central Iowa by mid to late afternoon. Remnant tropical moisture from Paine will probably still be available at this time across our area. With a ribbon of higher precipitable water and decent convergence along the boundary...will likely see a decent rain event with up to an inch additional from Saturday evening through Sunday. Once this feature pulls east...the models are in some consensus for next week. Both the Euro and GFS now suggest that the H500 long wave trough will keep the moisture channel south and east of the region. This should allow for a period of little to no precipitation and help the river situation across the area. Temperatures next week look cooler and more seasonal for the first week of fall. && .AVIATION.../For the 18Z TAFS through 18Z Friday afternoon/ Issued at 139 PM CDT Thu Sep 22 2016 Conditions are generally improving with VFR in most locations and only a few MVFR spots. Weak convection will also linger in the KALO area through the afternoon. The question becomes convection and cig/vsby trends into the night and there is low confidence again in that regard. Until confidence increases have only included VFR conditions and vicinity wording rather than prolonged periods of thunder and/or category degradations. && .HYDROLOGY... Issued at 307 PM CDT Thu Sep 22 2016 Magnitude and placement of the heavy rains will be key tonight. As mentioned above the environment is not as favorable as last night but still supports heave rain. The surface based potential is trying to recover with uncapped 1500-2500 j/kg MLCAPEs now in place over SW IA. This recovery may be too late to get anything going, but will likely aid slightly elevated convection just to the north and east tonight. The latest objective analysis pegs 0-2km moisture convergence along the Highway 20 to 30 corridors so this will be the favored location, likely anchored along or just south of the current Waterloo MCS which won`t go away. Precipitable waters are already around 2 with warm cloud depths higher than yesterday to 4km. Thus the moisture transport and instability components will not be as good as yesterday, but efficient rains are still anticipated. This will result in 1 rainfall amounts through the aforementioned favored corridor with locally higher amounts from 2-3 possible, thankfully south of where yesterday`s heavy rain occurred. Storms will not be fast moving with a mean of only 15-20kts and Corfidi vectors slow to the south. Thus have kept the flash flood watch in place through 18z Fri and expanded down to the full Highway 30 corridor from Guthrie County eastward. A small section of west central IA counties has been canceled however, which does not seem to be under the gun and didn`t receive much rain overnight. && .DMX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Friday afternoon for IAZ004>007- 015>017-023>028-034>039-046>050. && $$ SHORT TERM...Small LONG TERM...REV AVIATION...Small HYDROLOGY...Small
Area Forecast Discussion
National Weather Service Hastings NE
417 PM CDT THU SEP 22 2016 .SHORT TERM...(This evening through Sunday daytime) Issued at 417 PM CDT Thu Sep 22 2016 Forecast highlights/overview of these next 72 hours: The primary concern through these 72 hours centers around the still-somewhat- unclear rain/thunderstorm chances centered on the Friday night- Saturday night time frame (rain chances/PoPs have been held below "likely" 60+ percentages at this time due to inherent uncertainty in coverage). Assuming that at least isolated/scattered activity is able to develop during this time frame, a few strong to severe storms are not out of the question, especially Saturday afternoon within eastern parts of the CWA. Turning back to the nearer-term, have left the forecast void of any mentionable (meaning 15+ percent) shower/storm chances through tonight, but these chances are not necessarily "zero" either. There is some concern for at least patchy fog development mainly within counties along/especially north of I-80 tonight, with a few higher-res models such as the HRRR suggesting that this fog could be a bit more widespread/impactful. For now, have not gotten very aggressive but did at least introduce a mention of "patchy fog with visibility less than 1 mile" to tonight`s forecast. Temperature-wise, unlike today, Friday is expected to have a more uniform temperature regime with well-above normal heat in all areas. Then, a gradual cool-down should occur over the weekend, with highs by Sunday actually slightly below normal (and roughly 20 degrees cooler than Friday). Taking a look at the current scene as of 330 PM (and as outlined in the "update" discussion earlier this morning)...sky cover/temperature forecasting has been a bit of an "adventure" today thanks to a stark division between widespread sun/heat over southern/eastern counties and a nearly solid deck of low stratus clouds over many northern/western counties. As expected, the southern/eastern edges of this low stratus has in fact slowly retreated/eroded off to the north and west in response to daytime heating and mixing. Gave a "best shot" at where actual high temps will end up, but currently it appears a rather big gradient from low-mid 70s far north/west-central...mid 70s to low 80s in the central Tri-Cities area...and noticeably hotter upper 80s to low and even mid-90s in far eastern and southern counties (hottest of all in our southern-most KS zones). At the surface, the edge of this stratus is fairly closely tied to the position of a nearly- stationary front that is draped across the CWA from west-southeast to east-northeast. Fairly light north/northeast breezes prevail north of this boundary while southerly breezes prevail to its south...and a hodge-podge of light/variable in between. In the mid-upper levels, a period of weak/subtle ridging appears to be in control of the Central Plains between a departing shortwave over IA, and a powerful/highly-amplified trough over the western CONUS featuring a deep closed low centered over NV. Now looking ahead forecast-wise through these next 6 day/night forecast periods... This evening/tonight: Despite various hints in various models that at least spotty shower/thunderstorm activity could at least flirt with the fringes of our CWA (especially northern areas after dark), decided that the overall coverage of any of this possible activity within our borders would remain closer to 10 percent than 20 percent, and thus these chances are below mentionable thresholds (in other words, the forecast reads as "dry" but please note that chances are not necessarily zero). Certaintly, the most legitimate rain/storm chances tonight should focus north of our CWA from northern NE eastward into IA, where mid level temps are a touch cooler and where there is better convergence near the nose of a modest low level jet. At the surface, the aforementioned front draped across the heart of the CWA will slowly lift northward as a warm front overnight in response to low pressure deepening to the west, turning breezes more southerly as it does so. It is still unclear exactly what the low stratus deck does, as its northward-retreat is likely to stall out for a time around nightfall, keeping it stubbornly over our northern/west-central zones well into the night before eventually vacating our CWA for good. As mentioned in the opening paragraph, there are hints of fog development overnight mainly in counties north of the I-80 corridor, and have introduced a generic "patchy with visibility less than one mile" to get the ball rolling this direction. Temp- wise, if anything nudged down lows very slightly, aiming for mid- upper 60s most areas but low 60s far north. Friday daytime/night: This is "part 1" of our upcoming rain/storm chances, and confidence is pretty high that they will not even arrive in western zones until after dark. In the mid-upper levels, the aforementioned deep western trough will gradually approach/invade the Central Plains, with its primary mid level vort max reaching western WY by late afternoon, and into southeast MT by daybreak Saturday. Ahead of this system, confidence remains rather high in a dry, mostly sunny and very warm (some would say hot) day with noticeably breezy southerly winds overtaking the entire CWA as the warm front blasts well to our north. Made little change to high temps/winds, as the entire CWA is expected to top out 88-91 in the presence of sustained south winds 15-25 MPH and gusts 25-25 MPH, highest in the afternoon. Then, as the night wears on, forcing gradually increases from the west, and fairly low chances for isolated to perhaps scattered of showers/thunderstorms arrive to the western CWA before midnight and then expand CWA-wide late in the night. Can`t completely rule out a rogue strong to marginally severe storm mainly with hail, but this should be the exception. The invading north-south oriented synoptic cold front may be right on our western doorstep by night`s end, but ahead of this boundary low temps should hold up mid-upper 60s most areas. Saturday daytime/night: This is "part 2" of the storm chances, but confidence in areal coverage of this rainfall is still not high enough to justify "likely" PoPs within the CWA. Certainly though, chances are higher in southern/eastern counties than they are in northern/western counties (which could really end up missing out on things). In the mid-upper levels, the main vort max swings north toward ND during this time, while the large-scale trough trailing to its south slowly edges east through the Plains. Meanwhile at the surface, barring some fairly big changes, models have seemingly settled on a steady west-to-east progression of the synoptic cold front through the CWA during this time. Based on instability/shear progs and the timing of the boundary, especially our eastern-most counties may see at least a brief severe storm threat Saturday afternoon along this front, and agree with the SPC putting these areas in a Marginal Risk. This will bear watching, because if the front slows at all, then more of our CWA may be in a severe risk mainly for large hail/wind. Taking the latest models literally (especially the NAM) suggest that the majority of shower/storm chances may be over with by sunset. However, models such as the ECMWF/GFS are slower with precip departure, and thus will linger modest PoPS through the night especially in eastern/southern zones. High temps are aimed low 80s most areas and with With cooler air invading, lows expected to drop into the 50s nearly all areas. Sunday daytime: Although it could be a close call in extreme southeast zones, confidence was high enough to leave the entire CWA void of shower/storm chances behind the departing cold front. As a result, we are looking at a "fallish" day featuring plenty of sunshine, cooler temps and breezy northwest winds averaging 15-20 MPH with higher gusts. If anything, nudged up highs 1-2 degrees given expectation of sun/decent mixing, aiming for 69-72 most areas. .LONG TERM...(Sunday night through Thursday) Issued at 417 PM CDT Thu Sep 22 2016 Fall-like conditions are forecast to continue on into the beginning of the next work week, with temps climbing back to normal by mid- week. The main change made to the forecast for the long term was to remove precipitation chances. At the start of the period, models are in pretty good agreement showing the main upper level trough axis continuing to push through/east of the CWA. By 12z Monday, the axis looks to extend from central MN south through central KS, with northwesterly winds in place across the CWA. That northwesterly flow aloft remains in place through at least Mon/Tues, as ridging over off the west coast starts pushing east through the Rockies. As we get into Wed/Thurs, that ridging moves onto the Plains/right over the CWA. The 12Z run of the ECMWF/GFS are in good agreement showing little in the way of disturbances moving through, keeping this dry. The 12Z run of the Canadian is an outlier, keeping a massive cut off lower pressure system over the central CONUS through the period. At the surface, high pressure builds into the region behind the weekend frontal passage, with light, northerly winds on Monday turning more variable for Tuesday. Return southerly flow looks to return for mid-week. As far as temperatures go, not expecting a lot of change for Mon/Tues compared to Sun, with highs generally in the mid-upper 60s and dewpoints in the 30s and 40s. Warmer temps forecast for mid-week with the upper ridge building in, reaching the mid 70s by Thursday. && .AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday afternoon) Issued at 1237 PM CDT Thu Sep 22 2016 Although confidence is rather high in VFR conditions especially by the final 6 hours of the period Friday, and confidence is high in IFR/MVFR ceiling at least during these first 2-4 hours this afternoon, there is still a fair degree of uncertainty lurking within the hours in between. Read on for more element-specific details... Ceiling/visibility: Needless to say, ceiling trends have gotten considerably more pessimistic since the last routine 12z issuance, especially for these first 12 hours. A low stratus deck (currently IFR) has moved southward into the area, and although confidence is high that it will persist at KGRI/KEAR for at least a few more hours, already by late this afternoon there are some models/guidance that try scattering it out while others hold firm at MVFR levels. For now, will side with the more pessimistic side of solutions and maintain MVFR well into tonight before bringing back VFR by around 07z as this low cloud deck is expected to finally retreat northward by then (if it hasn`t already), with VFR thereafter. As for visibility, cannot rule out at least some light fog overnight, but for now have kept visibility low-end VFR and only "hinted" at possible fog with a "6SM BR" mention. Surface wind and low level wind shear (LLWS): At the surface, winds will undergo some noticeable changes during the period. Starting off this afternoon/evening, a fairly light north/northeast breeze will prevail just to the north of a nearly stationary front. Then, during the latter half of the period, and especially during the final 6 hours, a switch to a more pronounced southerly wind will take hold as this front surges northward. By the last few hours of the period around mid-day Friday, gusts of at least 20-25kt should be common. Meanwhile, accounting for increasing southerly winds just above the surface tonight, have introduced a period of fairly marginal LLWS from 07z-14z as the magnitude of shear between the surface and roughly 1000 ft should average around 30kt during this time frame. Precipitation/thunderstorm chances: Although there is a very small, non-zero chance of a passing shower/weak thunderstorm mainly tonight, this chance is certainly too low for formal TAF inclusion. && .GID Watches/Warnings/Advisories... NE...None. KS...None. && $$ SHORT TERM...Pfannkuch LONG TERM...ADP AVIATION...Pfannkuch
Forecast discussion for routine afternoon forecast issuance

.SYNOPSIS... Issued at 223 PM CDT Thu Sep 22 2016 A break in the excessively wet weather, but temperatures remaining near or above seasonal normals. Currently on the large scale, strong Pacific jet splits near the West Coast before merging back together in the Great Lakes region. The pattern will be slowly progressive, especially early in the forecast period. Ridging building northeast from the eastern Pacific will force the location of the split eastward into the Plains by the weekend. Thereafter, the evolution of the flow regime becomes uncertain as the medium range models offer varying ideas on the handling of the remnants of the current southern stream upper trough. That uncertainty will impact precipitation chances during the latter part of the forecast period. Temperatures are expected to remain near to modestly above seasonal normals through most of the the period, though they could tail off late. Shower chances will continue the next couple days, especially across the southern part of the forecast area. But rainfall amounts should remain on the light side. Precipitation chances during the middle to latter part of the period will depend on the evolution of the current southern stream upper trough now over the western CONUS, and thus are a low-confidence aspect of the forecast. The best estimate is that rainfall totals for the next 7 days will end up AOA normal, though at this point amounts do not look excessive. && .SHORT TERM...Tonight and Friday Issued at 223 PM CDT Thu Sep 22 2016 The latest RAP analysis and satellite/radar imagery show a nearly stationary surface cold front stretching from west-central WI to near Wausaukee early this afternoon. Scattered morning showers died off along the boundary by midday, but the hi-res models continue to indicate that a few showers will be possible over east-central and far northeast WI and within a pwat axis through the rest of the afternoon. Not convinced that will occur since there is little to no instability, but left a small chance just in case. Observations also indicate the presence of some drizzle over far northwest Wisconsin within a band of low clouds behind the front. Some of this drizzle could move into Vilas county later this afternoon. As the front finally makes a move southward tonight, small precip chances and cloud cover are the main forecast concerns. Tonight...The cold front will finally move south across central and northeast WI this evening, and into southern WI overnight. Position of the pwat axis and hi-res models indicate that east-central WI could see a shower or two early in the evening before the front exits the forecast area. But will leave a slight chance across the south in case the front is slower to exit than progged. Otherwise, should see widespread cloudiness linger behind the front per satellite imagery. A developing northeast breeze should keep the boundary layer churned up to limit fog potential even after all of the rainfall. Lows falling to near 50 in the north to near 60 in the south. Friday...The cold front will settle over far southwest Wisconsin and northern Illinois. A band of low clouds are expected to remain behind the front, which should keep central and east-central WI more cloudy than over northern WI, where northeast winds will push in drier air. Cannot rule out a few showers over central and east- central WI in a region of modest mid-level fgen. Because of more sunshine, northern WI could be as warm or warmer than locations further south. Will go with highs mostly in the mid 60s. .LONG TERM...Friday Night Through Thursday Issued at 223 PM CDT Thu Sep 22 2016 Weak isentropic lift will begin spreading back across the area Friday night. That seems worthy of having chance PoPs expand northeast across most of the area during the night, though with limited instability opted to leave thunder out of the forecast. Though confidence in precipitation forecast for the rest of the period is probably lower than normal, leaned toward the ECMWF for PoPs. The 12Z EC was fairly consistent with its previous run, and exhibited decent consistency with the GFS ensemble mean. That resulted in a prolonged period of chance PoPs as the upper trough crosses the area. The best chance for rain looks to be Sunday and Sunday night, though that could easily chance in later forecasts. No significant changes were necessary to the extended forecast initialization grids based on a broad blend of guidance products. && .AVIATION...for 18Z TAF Issuance Issued at 1155 AM CDT Thu Sep 22 2016 A nearly stationary frontal boundary extending from west to east over northern WI will slowly sag south tonight. Some spotty light showers may still impact the Fox Valley and lakeshore areas for the rest of the afternoon into tonight, but not expecting much impact to the flight categories. Plenty of uncertainty in regards to ceilings behind the front tonight. Guidance is all over the map, but based on the widespread ifr cigs right behind the front, expect ifr/mvfr cigs to spread southward late this evening and overnight. Since will have a NE wind, think fog potential/low vsbys is less of a concern, especially over eastern WI. Ceilings then should improve my late morning on Friday. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS.......Skowronski SHORT TERM.....MPC LONG TERM......Skowronski AVIATION.......MPC
Area Forecast Discussion
National Weather Service Wilmington NC
640 PM EDT Thu Sep 22 2016 .SYNOPSIS... Weakening low pressure will drift offshore of the Carolinas through late Friday, taking the rainfall threat with it. Weak high pressure accompanied by drier air will prevail on Saturday. A modest cold front will drop south across the area early Sunday. Modest high pressure will follow and ridge across the area from the NE states through the early to mid week period of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 600 PM Thursday...POPs have been increased thruout this evening with the going concern being the continued moderate to heavy rain being produced by the convection. Lightning data has been limited/sparse across the Carolinas and therefore will just mention isolated thunder thru mid-evening. With the moderate to heavy rain persisting well into this evening, unlike what the latest HRRR and RAP indicate, have updated the pcpn phraseology to include "heavy rain". In addition, with a half a dozen of Flood Advisories issued, have updated the Hazardous Weather Outlook to include the potential for temporary ponding or shallow flooding from this evenings local heavy rains. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Low pressure over the Cape Fear area will weaken and move east through Friday as high pressure builds down from the north. The main mid to upper trough will lift off to the north and east and a ridge builds over the southeast, although both the ECMWF and the GFS show a low cutting off from the main trough and lingering across the deep south into Sun. A weak backdoor front will make its way south through VA and into NC Sat night and should reach into SC by Sun morning. Pcp water values up close to 1.9 inches on Fri mainly aligned along the SC/NC coast will diminish to less than 1.5 inches by Sat aftn with drier air and subsidence finally scouring out the remaining moisture from this persistent remnant low from Julia. Therefore, will continue with higher pops and greatest chc of shwrs/tstms on Fri mainly east of I-95 to the coast as sfc low remains just off the tip of Cape Fear. Expect clearing to occur through late Fri into Sat as Dry air and subsidence work there way south and east as upper ridge builds east through Saturday. This should produce plenty of sunshine across much of the area, but lingering moisture along the coast should produce some cu and possibly some isolated showers mainly over the SC coast Sat aftn. Not expecting much change in the feel of the air mass with humid weather continuing. Clouds will be tough to break on Fri with continued showers and therefore expect high to be in the 70s much of the day, but places that break out in the afternoon should reach into the 80s. Saturday will warm well into the 80s with a good deal of sunshine across much of the area. Overnight lows will be in the mid 60s to around 70. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 AM Thursday...A mid-and-upper level ridge axis will shift from the TN valley Sunday to the east coast by Tuesday, and will amplify between two anomalously strong upper lows into a Omega block-type pattern. At the surface, high pressure will ridge down across the mid-Atlantic states and produce onshore flow through the period. Although the primary belts of deepest moisture will remain south and west of the area, persistent onshore flow below 850 mb would provide sufficient moisture to support scattered showers. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 18Z...Expect at least tempo mvfr conditions into the evening hours in scattered showers and thunderstorms. conditions are expected to deteriorate to ifr levels again tonight with a slow transition after sunrise to vfr or mvfr conditions. light, mainly northeast to east winds are expected through the taf period. EXTENDED OUTLOOK...Isolated to scattered convection, mainly during the afternoon and evening hours is possible beneath the cutoff upper low through Friday. MVFR/IFR morning stratus/fog possible each day through Saturday. Expect mainly VFR Sunday through Tuesday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 600 PM Thursday...A relatively relaxed sfc pg will yield 10 kt or less wind speeds tonight. The progged sfc pressure field itself paints the elongated sfc low, underneath the upper low, straddling the coasts of NC and SC thru tonight. Could go variable in direction especially with speeds only at 5 to 10 kt, but instead will identify the more predominate directions, southeast to south. Significant seas will primarily be driven by a 1.5 to 2.5 foot, e to ese ground swell from distant Tropical Cyclone Karl. Latest Spectral Density Chart for 41013 indicates the ese 11-13 second period Karl swell is definitely driving the significant seas. Have increased the convection coverage this evening based on latest KLTX 88D trends. In addition, have highlighted the persistent convection over the northern-most waters oriented parallel to Cape Fear, as it pushes northward and onshore. Waterspout(s) has/have been sighted earlier today in the vicinity of this pcpn. Will mention this waterspout risk until sunset in the Hazardous Weather Outlook. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Low pressure just off the tip of Cape Fear will finally move away as high pressure builds down behind through Saturday. A cold front will drop south reaching NC Sat night and should move through the waters by Sun morning. This may be fairly transparent as winds will have already shifted to the N-NE by late Fri as low weakens and shifts east. Therefore light and variable winds on Fri will become northerly by early Sat and will remain N to NE through Sat night increasing up to 15 kts. Seas 3 ft or less will increase up to 2 to 4 ft into Sat night. A longer period SE-E swell will continue through the weekend, up to 11 to 12 seconds. LONG TERM /SUNDAY THROUGH MONDAY/... As of 300 AM Thursday...Surface high pressure will build down the eastern seaboard behind a cold front, which should be crossing the waters during the day Sunday. With a blocked upper-level pattern developing through the first of the week, the surface high will persist and result in onshore flow through Monday. It does still appear that 3-4 foot swells every 10 seconds will continue into Sunday from distant tropical system Karl, falling off to a 2-3 foot wind wave by Monday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DCH NEAR TERM...DCH SHORT TERM...RGZ LONG TERM...CRM/RGZ AVIATION...SGL
Area Forecast Discussion
National Weather Service Lincoln IL
300 PM CDT THU SEP 22 2016 .SHORT TERM...(This evening through Friday) ISSUED AT 259 PM CDT Thu Sep 22 2016 Unseasonably warm conditions will continue in the short term as upper level ridging holds over much of the Midwest and a nearly stationary front remains from eastern Nebraska across central Iowa into southern WI. Spotty showers across southeast Iowa this afternoon are trying to work their way into northwest IL, but plenty of mid-level dry air should result in rapid dissipation. Wouldn`t be surprised to see a few sprinkles make it through toward Galesburg early this evening, but not enough for measurable rainfall. Only the GFS and SREF are allowing for light rainfall overnight, with the other models continuing dry weather for us and keeping the focus on waterlogged areas of NE Iowa and SW Wisconsin overnight. The upper level ridge is expected to strengthen a bit over us on Friday which will keep the synoptic front to our north. This will result in another very warm day with highs around 90 in much of central IL. The exception will be in areas roughly north of I-74 where a few more clouds will keep temps in the mid 80s. With the front to our north and only a light south wind/very weak convergence will keep the rain chances out of the forecast through Friday. && .LONG TERM...(Friday night through Thursday) ISSUED AT 259 PM CDT Thu Sep 22 2016 The 12z models have kept a similar solution for Friday night through Sunday, with warm and humid conditions in Illinois under upper level ridging. A long wave trough over the central Rockies on Friday with lift NE toward Canada this weekend. This will cause a sharpening of the ridge across Illinois. Southwest flow aloft will increase as a result, bringing a continued flow of low level warmth and humidity. Highs will likely maintain in the mid 80s to around 90 Saturday and Sunday, with overnight lows in the mid to upper 60s. Dewpoints will linger in the mid to upper 60s, creating a muggy weekend. Precip chances for the first half of the weekend look to remain primarily north of Illinois, closer to a warm frontal boundary. However, there is continued support in the ECMWF, GFS and NAM that a cold front will push across IL on Sunday or Sunday evening. The NAM is the fastest, pushing it to the Indiana border by 7 pm Sunday/00z Mon. The GFS and ECMWF are next in timing, indicating the front should reach the Indiana border shortly after 06z/1am Monday. The Canadian Global halts the front near the Mississippi river in response to cutting off the Plains upper low and drifting it south toward Oklahoma on Monday. We held with the consensus of a frontal passage later on Sunday into Sunday evening, with increasing chances of storms Sunday afternoon west of I-57. Storm chances look to continue in the post frontal airmass through Monday, as the upper level trough axis finally progresses across the area. A cooler and less humid air mass will arrive for Monday, and linger through Thursday. While we see slight chances of diurnal showers each day due to steep mid level lapse rates, most areas should remain dry. High temps from Monday to Thursday should be in the mid 70s, with lows in the mid 50s. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 1251 PM CDT Thu Sep 22 2016 Mainly thin cirrus clouds were moving east-southeast into central and eastern Illinois early this afternoon from the remnants of early morning thunderstorms back in northern Iowa. At the surface the main synoptic front extended from the central Plains across central Iowa into southern WI, with an outflow boundary from southwest WI into eastern IA. These boundaries are expected to stay north of the region today so a southwest wind should prevail. A little more mixing than previously anticipated will allow winds to stay at or a bit above 10kts in central/eastern IL the rest of the afternoon. Weak wind fields and very few clouds this evening should lead to rapid decoupling of the low levels of the atmosphere and pretty strong inversion. The RAP and CONSShort point to light fog developing toward daybreak, so included MVFR visibility for the TAF sites along the I-74 corridor. A lower crossover temperature at SPI and DEC should keep light fog from forming. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Miller LONG TERM...Shimon AVIATION...Miller
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
416 PM CDT THU SEP 22 2016 .SHORT TERM...(This evening through Friday) Issued at 415 PM CDT Thu Sep 22 2016 Warm front this afternoon has made it down to about I-80 in Iowa. It will begin lifting back north tonight. This will maintain the cloud cover overhead through the night and the day on Friday, but precip fortunately looks to be lacking. There are a couple of reasons for this. One, we have building heights at h5. Two, the 925-850 winds will be diverging over the region with a weak segment going from Iowa toward southern WI and the main push going from the eastern Dakotas to the western Dakotas. This 925-850 setup looks to stay with us through the day on Friday with the models showing their primary focuses for precip through Friday across northeast Iowa into southern WI and way out in the northern high Plains. As a result, cut back considerably on PoPs tonight through Friday, with most of the area remaining dry through the short term. Isolated activity in the form of mostly showers as opposed to thunderstorms, is looking to be the best we see as the boundary lifts back north. .LONG TERM...(Friday night through Thursday) Issued at 415 PM CDT Thu Sep 22 2016 We will finally get the upper trough to our west out of here by the end of the weekend, but until then we`ll have a few more periods of precipitation with which to contend. It appears most activity will be to our north Friday night with the warm front and better isentropic lift located there, although some low PoPs for part of the area are still warranted. The western upper trough will start to shift east on Saturday, helping the surface low lift north to near the North Dakota/Canada border and push the cold frontal boundary east toward Minnesota. We should see fairly SHRA/TSRA develop in a north-south axis across the area during the afternoon as some upper divergence and DPVA work into the area and help take advantage of decent moisture and some instability. Although the cold front will certainly not be a fast mover, it should move quickly enough to avoid any widespread flooding issues. But, any additional precipitation will certainly be problematic at this point, and it looks like we could have some areas with over an inch of rain from Saturday afternoon through Sunday morning, and it will unfortunately be over the central and eastern portion of the area which has seen substantial rain of late. The cold front will push east of the area by Sunday evening, but we will then have the upper low and low level cyclonic flow linger into Tuesday. So, although the widespread precipitation will be done, we`ll likely see scattered showers Monday into Tuesday with cool temperatures. Things then dry out and start warming up for Wednesday and Thursday as the upper low shifts east and a surface high and rising heights work into the area. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 123 PM CDT Thu Sep 22 2016 Main question this period is how much influence will dry air from east winds emanating from a Hudson high influence the area. The hrrr is the most aggressive with pushing MVFR or lower cigs southwest of the MN river, with most terminals going vfr late this afternoon and remaining there through much of the night. SREF probs are similar as well. Was not quite that aggressive with the TAFs, but did introduce significant VFR periods to WI terminals who will be closer to the high and was conservative with keeping IFR conditions tonight confined to RWF. Also kept TAFs dry, with most models indicating we`ll see two focused areas of precip through Friday morning. One down toward northeast IA into southwest WI and the other way back in the western Dakotas. KMSP...CIGS are the main issue here. We may see a passing shower Friday afternoon as the warm front lifts back north, but this TAF period is looking to bring a much needed 30 hour break from precip. For CIGs, LAMP maintains an MVFR cig the whole period, which is plausible, but the SREF and HRRR have MSP going VFR tonight. Of course we could always head the other direction as east winds are a favorable direction for getting low CIGs, which is why we split the difference for now and went with a low MVFR cigs returning tonight. /OUTLOOK FOR KMSP/ Sat...VFR with MVFR/TSRA likely late. Wind SE at 10g15kts. Sun...VFR. Wind W-SW 10g20kts. Mon...Chc mvfr/-shra. Wind SW 5-10kts. && .MPX Watches/Warnings/Advisories... WI...None. MN...None. && $$ SHORT TERM...MPG LONG TERM... AVIATION...MPG
Area Forecast Discussion
National Weather Service Phoenix AZ
222 PM MST THU SEP 22 2016 .SYNOPSIS... Showers and a few thunderstorms will be possible today along and ahead of a cold front moving through the region. This front will bring gusty winds, drier air, and slightly cooler temperatures for the remainder of the week. Breezy, but otherwise quiet weather will be the rule for the weekend and into early next week along with a warming trend. && .DISCUSSION... Initial line of showers steadily dissipated as it tracked eastward across the Phoenix area early this afternoon. In its wake, more scattered but organized storms have developed across portions of western Maricopa County within a moist and unstable environment with dewpoints as high as the lower 70s yielding MLCAPEs exceeding 1000 J/kg. Meanwhile, NAEFS percentiles show a widespread area of anomalous PWATs, exceeding the 90th percentile across central AZ extending northward. Latest runs of the HRRR continue to have a good handle on the situation and indicate that additional activity will develop this afternoon before dissipating around 5pm. The strongest storms are expected generally to the north and west, where temperatures aloft are cooler and in the vicinity of the strongest deep-layer shear associated with the closed low across central California. Main threats include brief heavy rain, strong winds gusts and small hail. Otherwise, PoPs remain in the forecast overnight for southern Gila County. Global models continue to suggest strong vorticity-forced ascent ahead of the trough axis will tap into some residual moisture to generate scattered showers in these areas. && .PREVIOUS DISCUSSION... Gusty west winds are expected to develop over the western deserts this afternoon behind the front, with the strongest winds likely to occur over favored areas of Imperial county; peak gusts to 35 mph are likely. There may be some patchy blowing dust occurring due to the wind, but recent rains in the area will limit the potential for any significant dust and as such we will not mention blowing dust in our forecast grids at this time. As far as temperatures go today, with thickness values lowering to around 576dm and with considerable lower clouds and showers in the area, high temperatures will fall to well below seasonal normal values with many lower AZ deserts falling into the upper 80s to low 90s. Phoenix should see a high around 90 today which would be 8 degrees below normal. On Friday, the main upper low is forecast to quickly lift off to the northeast but a much drier and more subsident northwest flow aloft will overspread the deserts. Outside of a lingering slight chance of showers over southern Gila County we can expect generally sunny skies over the lower deserts with continued below seasonal normal high temperatures. PWAT values are forecast to fall to around one quarter of inch over much of the lower central deserts by Friday afternoon and the surface dewpoints in the Phoenix area will fall from the mid to upper 60s today into the upper teens to mid 20s. Over the weekend and into next week, dry conditions are forecast area wide with no threat of precipitation. A large upper ridge will initially amplify along the west coast giving a dry northerly flow to the area but early next week the ridge will flatten somewhat but continue giving dry northwest flow into the lower deserts. Expect generally sunny days and clear nights this weekend into the middle portion of next week along with a gradually warming trend. High temperatures will climb into the mid to upper 90s over most of the lower deserts by the early to middle part of next week. .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Shower and thunderstorms continue to develop upstream of the Phoenix area terminals and all terminals stand a chance to see some precip activity through the evening hours. Airfield vsbys may take a sudden drop under the heaviest shower activity and resulting winds will also be on the rather variable and erratic side. Otherwise, CIGs will linger 3-5kft into the evening before transitioning eastward with FEW to SCT clouds lingering after sunset. Any continuing shower activity should move and stay east of the terminals for the overnight hours. Southeast California/Southwest Arizona including KIPL and KBLH: Breezy to windy conditions to persist for KIPL and KBLH as a cold front continues to pass through the region. Gusts 25 to 30kts will linger into the overnight, with sustained winds holding in the 10 to 15kt range. Skies will remain mostly clear with any shower activity remaining well to the east of the River and the terminals. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Saturday through Wednesday... Very dry northwesterly flow aloft behind a trough to the east on Saturday will eventually be replaced by a dry ridge of high pressure on Wednesday along with below normal high temperatures throughout the period. Breezy to occasionally windy northerly component winds will prevail out west, especially along the lower Colorado river valley each afternoon through Monday with gusts of 20 to 28 mph, although conditions are not expected to reach critical thresholds at this time. Gusty northeasterly winds will then spread into the lower deserts and the higher terrain of southern Gila county beginning Tuesday. Minimum RH of 13 to 20 percent on Saturday will slowly increase each day until reaching only 20 to 30 percent on Wednesday. Fair overnight recoveries on Saturday will improve to fair to good by Tuesday. && .SPOTTER INFORMATION STATEMENT... Spotter reports may be needed locally this afternoon across the Phoenix area. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Hirsch PREVIOUS DISCUSSION...CB AVIATION...Nolte FIRE WEATHER...Sawtelle