Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/10/16


Area Forecast Discussion
National Weather Service La Crosse WI
709 PM CDT FRI SEP 9 2016 .UPDATE...Tonight Issued at 709 PM CDT Fri Sep 9 2016 The heavy rain threat has ended across northeast Iowa into southwest Wisconsin so the Flash Flood Watch has been cancelled. Also, with instability rapidly diminishing, have removed thunderstorms from the forecast for areas mainly along and north of Interstate 90. && .SHORT TERM...(This evening through Saturday) Issued at 352 PM CDT Fri Sep 9 2016 At 3 PM, a short wave trough was moving northeast across Wisconsin. This system produced a widespread area of 1 to 4 inches of rain across the forecast area. With the radar underestimating the rainfall south of Interstate 90 corridor by up to 25 percent, would not be too surprised that there may be some areas which saw around 5 inches in northeast Iowa and southwest Wisconsin. With this initial wave pushing the surface front as far south as the Interstate 80 corridor, the best instability (up to 1500 J/kg) has ended up in southern Iowa and central Illinois. Further to the west, a much strong short wave trough was located across southwest Minnesota and western Iowa. This system will move east through the area tonight. The RAP continues to show that the elevated instability will climb up to 750 J/kg across northeast Iowa and southwest Wisconsin this evening. In addition, there will be moderate 925 and 850 mb moisture transport, warm cloud layer cloud depths to around 4 km, and precipitable water values approaching 2 inches. This will result in highly efficient rain producers. Taking all of this in account, anticipating that some areas may see up to another inch from this system this evening. With ongoing flooding occurring in some areas and saturated soils across the region...kept the Flash Flood Watch going through 10.06z. However would not be too surprised that we are able to cancel this watch early. On Saturday morning, a short wave trough currently over South Dakota will move across northern Wisconsin. This system will produce some scattered showers mainly along and north of Interstate 94. .LONG TERM...(Saturday night through Friday) Issued at 352 PM CDT Fri Sep 9 2016 The next chance of rain will likely occur from Monday night into Tuesday. As the 925 and 850 mb moisture transport increases ahead of the cold front and approaching short wave trough, precipitable water values will climb into the 1 to 1.5 inch range. However considering the progressive nature of this system and warm cloud layer depths less than 3.5 km, not anticipating any additional flooding from this system. While the 0-1 km mixed layer CAPE will be climbing up to 1250 J/kg ahead of the front, both the 0-3 and 0-6 km shear will be lagging the front; thus, not anticipating any threat of hail, wind damage, or tornadoes from this system. In the wake of this front, high pressure will build across the region. This will help provide us with some much needed drying through Thursday. As a result, the weather still looks good for our Open House which is on Thursday from 2 PM to 7 PM. Hope to see some of you there. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 709 PM CDT Fri Sep 9 2016 MVFR conditions are possible in stratus and light rain showers tonight into early Saturday morning. Scattered to broken cumulus are expected on Saturday and there may be some brief MVFR conditions, but at this time cloud bases are expected to remain VFR through the day on Saturday. && .HYDROLOGY... Issued at 709 PM CDT Fri Sep 9 2016 The threat for heavy rain has ended. Flooding continues along portions of the Upper Iowa, Turkey, and Kickapoo Rivers. Minor Flooding is expected. Significant rainfall is not expected over the next few days. && .ARX Watches/Warnings/Advisories... WI...None. MN...None. IA...None. && $$ UPDATE...WETENKAMP SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...WETENKAMP HYDROLOGY...WETENKAMP
forecast discussion outlines this topic well. SE Michigan will
remain precariously positioned along the immediate eastern flank
of the inbound surface low, with a substantial component of SRH emerging as the warm frontal zone works into the region. With that said, lack of greater low level instability remains an issue, reinforced by incoming forecast sounding data via both the HRRR and RAP. PREV DISCUSSION... Issued at 414 PM EDT Fri SEP 9 2016 DISCUSSION... Observational evidence including water vapor imagery confirms a deep midlevel trough with dual shortwave circulations settling down along Rocky Mtns and into the western Dakotas this afternoon. Model progs support a phasing of these shortwave centers over the northern Mississippi River Valley by 12z Saturday. Very strong synoptic scale forcing, including a tremendous amount of upper level diffluence from coupled jet structure will support a rapid cyclogenesis event over portions of Wisconsin, U.P., and Ontario on Saturday. Tonight...A tremendous increase in anticyclonic curvature to the upper level jet core north of Lower Michigan tonight will cause a rapid increase in warm air advection locally in addition to drawing lead shortwave energy firehose directly over the cwa. The shortwave of interest for the tonight period is the circulation now driving shower activity and returns over central Illinois. Hires model data is all over the board on this with much of the forecasted activity on the bearish side and suggesting most activity to pass along or south of the Michigan and Ohio border. Latest global run of ECMWF and Nam runs show much more of a direct hit south of I 69 late tonight after 06z. This includes a very well organized and deep closed low pressure center lifting into portions of southwestern Lower Michigan late tonight. Given the location of strong synoptic forcing both in terms of upper level jet forcing and the proximity fo the cwa to the nose of fresh, backed low level jet convergence will be continuing the likely or numerous pops for the area. While some solutions are on the lean side, do think there is a good QPF potential from SW to NE between 05-14Z perhaps up to a .50 inch. Latest SWODY1 has a marginal designation for severe weather south of Detroit for late tonight, perhaps conditional to any new convective updrafts that will be able to generate to the east of the midlevel low pressure circulation in the 07-10z timeframe. A very high end shear environment, i.e. 50 knots down to 850mb and 0-3km SRH of over 400 m2/s2, is expected to be in place which brings some concern. However, most, if not all, of the guidance suggests elevated convection with a residual stable layer persisting between 1500 and 5000 ft agl. Saturday...Main warm front precipitation and frontal wave from upper level divergence maximum and low level jet forcing convergence will lift north of the cwa by 15Z. Thus, expecting precipitation to shut down by the mid morning but a grungy environment will persist, one mired in low clouds. Signal exists in the data that a secondary increase in dewpoints will occur by late morning with surface dewpoints solidly in the lower 70s F along a narrow corridor over the extreme eastern cwa. It is along this narrow dewpoint gradient that the potential for severe weather appears to exist in the 17-19Z time window. The concern is that with 40 knots of 0-6 km bulk shear and upwards of 1250 to 1500 J/KG of MLCAPE possible the potential for rapid development of supercellular convective mode will be possible. The limiting factors to severe weather will be morning clouds, and early afternoon passage of dewpoint front. The second item for Saturday will be the potential for breezy conditions with gusty west winds primarily between the 20z to 02Z timeframe. Increased wind gusts into the 25 to 30 mph range across the board. Sunday...Extremely rapid increase in geopotential heights will support subsidence and High Pressure on Sunday. Completely different environment is expected for Sunday with much more in the way of early autumn weather. Looking at highs Sunday in the lower 70s with dewpoints surprisingly down into the 40s by the afternoon. Dry weather. High pressure holds over the area for Monday with dry conditions and low humidity continuing. Meanwhile, a developing low over the four corners begins to push northeast merging with a Canadian low. The cold front associated with these systems will push through on Tuesday/Wednesday bringing in chances of showers/thunderstorms. In the wake of the front, high pressure builds over southeast Michigan and temperatures drop significantly. High temps are only expected to reach the upper 60s Wednesday/Thursday. Gradual warming into the low to mid 70s for the weekend. MARINE... High pressure will keep quiet weather over the area through this evening before a deepening low pressure system begins to lift through the Western and Northern Great Lakes and conditions deteriorate. Southerly winds will steadily increase tonight and early Saturday, with gusts increasing to between 25 and 30 knots by late Saturday morning. A round of showers and thunderstorm is also expected late tonight and early Saturday as a warm front lifts across the area, with a second round possible later in the day ahead of a cold front. Winds will turn to the northwest and increase late in the day as colder air rushes in behind the front and over the warmer lake surface. This will allow winds to gust to gale force over much of the open waters of Lake Huron late Saturday afternoon through much of Saturday night. Winds and waves will subside early Sunday morning as high pressure begins to rebuild into the Great Lakes. A small craft advisory is now in effect for all nearshore waters, and a gale warning is in effect for much of the open waters of Lake Huron. HYDROLOGY... Low pressure lifting across the Great Lakes will bring showers and thunderstorms to the area late tonight and Saturday, possibly in two rounds. The first will occur late tonight through Saturday morning, with a second round possibly developing in the afternoon. A generous coverage of showers and storms is expected overall within the next 24 hours, resulting in widespread precipitation amounts between 0.25 and 0.50 inches. Some thunderstorms will produce locally heavy rainfall however, producing greater than one inch of rain in a short period of time. This could lead to some localized flooding. Drier air behind a cold front will end the threat for showers and storms by mid-evening. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Gale Warning from 4 PM Saturday to 4 AM EDT Sunday FOR LHZ361>363- 462-463. Small Craft Advisory from 10 AM Saturday to 4 AM EDT Sunday FOR LHZ421-422. Small Craft Advisory from 10 AM Saturday to 10 AM EDT Sunday FOR LHZ441>443. Lake St Clair...Small Craft Advisory from 10 AM Saturday to 4 AM EDT Sunday FOR LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from 10 AM Saturday to 4 AM EDT Sunday FOR LEZ444. && $$ AVIATION.....MR UPDATE.......MR DISCUSSION...CB/DE MARINE.......HLO HYDROLOGY....HLO You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
915 PM CDT FRI SEP 9 2016 .UPDATE... /ADDED SLIGHT CHC POPS OVERNIGHT EAST & FAR WEST/ Merging cell clusters over Terrell County appear more likely to propagate east into western parts of Val Verde County this evening, but should still weaken and dissipate in the early morning hours. Evening analysis of the TUTT low moving through East TX reveals a stronger mid-level presence and therefore influence over the the weather over South Central TX. Recent runs of the RUC model suggest some early morning showers picking up over the Coastal Plains prior to daybreak. The 00z NAM also shows an increased impact on the approaching front to the north which will act to reduce frontal zone convergence over Central TX and possibly decrease rain potential for Saturday. Will not mess with the day2 PoP/wx grids for now, as QPF amounts from earlier are already modest. Only other adjustment was to add slightly more post-frontal wind over NW counties for Saturday based on mesoscale model trends. && .PREV DISCUSSION... /ISSUED 657 PM CDT FRI SEP 9 2016/ UPDATE... See below for the 00z aviation update... AVIATION... VFR conditions should prevail for the remainder of the evening at all terminals. MVFR/IFR ceilings should develop overnight - around 7z - for KAUS/KSAT/KSSF with patchy fog possible at KAUS. CIGs will improve to VFR by late morning/early afternoon on Saturday. KDRT will remain VFR throughout the entire forecast period. A cold front will move into the region from the north on Saturday bringing with it a chance for scattered showers and thunderstorms in the afternoon hours. PREV DISCUSSION... /ISSUED 308 PM CDT FRI SEP 9 2016/ SHORT TERM (Tonight through Saturday Night)... An upper level disturbance pushing towards the southeast Texas coast this afternoon is promoting dry weather over much of the region. However, an isolated shower or storm could still make it across the far east counties and coastal Plains where higher humidity levels/pwats reside. Clouds will increase late tonight with overnight lows generally in the lower to mid 70s. Rain chances increase Saturday into Sunday as a weak cold front pushes across the area. Best chances for rain are expected Saturday afternoon into the evening across the northern part of the area. Later in the the evening, showers and storms are expected to be focused out over the Rio Grande and south of Highway 90. Rainfall amounts could range from one tenth to one quarter inch and up to one half inch in some places. There may be isolated locations that could get near an inch especially across the Rio Grande. LONG TERM (Sunday through Friday)... Once the weak cold front clears the area, dry weather conditions are anticipated Sunday evening into Monday of next week as subtropical ridge builds over the dessert southwest. After that period, the medium-range models are having difficulties on handling the extended forecast period Tuesday through Friday. This forecast package shows a blend of GFS and ECM but slightly favoring the GFS solution. Therefore, there are rain chances every day of next week. Temperatures should be near normal values for the next five to seven days but a bit cooler Saturday night as the rain cool things down few degrees. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 75 90 71 89 72 / 10 50 20 20 0 Austin Bergstrom Intl Airport 74 89 71 89 70 / 10 50 30 20 0 New Braunfels Muni Airport 74 91 71 90 71 / 10 40 30 20 0 Burnet Muni Airport 73 87 69 88 70 / 10 50 20 10 0 Del Rio Intl Airport 75 92 73 90 73 / 10 30 50 20 - Georgetown Muni Airport 74 88 70 88 71 / 10 50 20 10 - Hondo Muni Airport 74 91 72 91 72 / 0 30 40 20 - San Marcos Muni Airport 73 89 71 88 70 / 10 40 30 20 0 La Grange - Fayette Regional 75 90 72 90 72 / 20 50 30 20 10 San Antonio Intl Airport 75 90 72 89 72 / - 30 30 20 0 Stinson Muni Airport 76 92 74 91 73 / - 30 30 20 - && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Treadway Synoptic/Grids...Oaks Public Service/Data Collection...Williams
Area Forecast Discussion
National Weather Service Green Bay WI
919 PM CDT FRI SEP 9 2016 Updated aviation portion for 06Z TAF issuance and new information added to update section .UPDATE... Issued at 906 PM CDT Fri Sep 9 2016 A rather complex forecast situation tonight. Precipitation has been slow to develop, and instability now waning. In addition, main frontal boundary is south of the area and should remain there. So the prospect for heavy convective rains looks very limited. However, the major shortwave approaching from the west is very impressive looking on satellite imagery. Plenty of lightning was detected within the base of the trough through the early evening, though that has since waned. The main QG forcing with the wave is still well to our west. The past several runs of the RAP and HRRR have been pretty consistent in showing precipitation increasing across the forecast area once the stronger QG forcing arrives later tonight. Given the strength of the upper system, that seems very plausible. Will adjust the forecast to lower PoPs for the rest of the evening, then increase them after midnight when the main forcing arrives. Also carried higher PoPs into tomorrow as suspect precip will be slow to exit the east. With the threat of heavy convective rains now lower, the potential for flooding has decreased. The main threat of heavy rain with the shortwave would probably be across far northeast Wisconsin if comma head pivots across that area. While the rain in that area may be a good soaker, totals should remain below what would result in flooding. Updated product suite will be out ASAP. && .SHORT TERM...Tonight and Saturday Issued at 251 PM CDT Fri Sep 9 2016 Main impacts in the short term will be the heavy rain pushing through tonight and Saturday which could lead to localized flooding. 19z sfc analysis showed a warm front draped over southern Wisconsin, with the CWA sitting on the north and cool/stable side of the front. An area of rain with occasional thunder did develop in response to WAA riding up and over the front. Rain pushed through central Wisconsin this morning into the early afternoon. However, the precip quickly diminished and stop its eastward progression as it ran into very dry air below 700mb in eastern Wisconsin. Cyclonic flow aloft left all of northeast Wisconsin under of blanket of clouds through the day. Still expect rain to develop this evening and overspread northeast Wisconsin. Despite strong cyclonic flow with an upper level trough overhead, having a hard time seeing precip develop as quickly as some of the models are advertising. There is a lot of dry air to overcome in eastern Wisconsin, and the WAA has decreased as the warm front got shoved south from this early afternoon rain. Slowed down the progression of rain eastward, and would not be surprised if east central Wisconsin remained dry through 00Z. Things should get going overnight into Saturday though as a complex weather system moves into the great lakes region. At the surface, a cold front will surge eastward through the CWA this evening, and exit by Saturday morning. As the cold front moves through, a sharp upper level trough will also be cross the region, with NE wisconsin sitting near the RRQ of an upper level jet. In general, there will be strong forcing overnight to allow for widespread rain so continued with likely PoPs in central and northern Wisconsin where the forcing will be strongest. With PWATs ahead of the front surging to around 1.5 inches or more, rain will be heavy at times. Dewpoints will also sneak up into the lower 60s ahead of the cold front so kept thunderstorms in the forecast through 12z Saturday when the cold front exits the area, however with limited instability the severe thunderstorm threat is low. With higher PWATs and scattered thunderstorms, some places in central and north central Wisconsin should see an inch of rain at least. Given the heavy rain event a few days ago in the same area, flooding is possible as rivers are running high and soil is saturated. Issued a hydro outlook to alert hydro partners, however additional headlines dont appear necessary at the moment as widespread flooding is unlikely. Some uncertainty as to how long precip will stick around on Saturday. The sfc cold front should clear the area by 12Z with west to northwesterly flow expected. However, the upper level system will still be overhead with strong forcing lingering over much of northeast Wisconsin through at least 18Z saturday. Hung onto chance pops through 18z, then tapered things off through the afternoon. Eastern wisconsin should see precip the longest as the trough finally lifts out and anticyclonic flow takes over late Saturday afternoon. Behind the cold front, expect gusty NW winds and cool temperatures. So even if it does stop raining Saturday, it still wont be a very nice outside for outdoor plans. .LONG TERM...Saturday Night Through Friday Issued at 251 PM CDT Fri Sep 9 2016 Fall weather looks to be a long ways off, as the medium range models forecast an almost summer like look at 500 mb through the next week or two. There will be slightly cooler weather during the middle of next week, but not any cooler than usual. Dry weather is forecast Saturday night through Monday afternoon before the next upper systems approach. There isn`t any low level moisture to speak of so only expect modest rains from showers and thunderstorms Monday night and Tuesday. Then northwest upper flow expected to produce dry, seasonable weather Wednesday through Friday. && .AVIATION...for 06Z TAF Issuance Issued at 906 PM CDT Fri Sep 9 2016 Scattered MVFR and even some IFR ceilings have developed during the evening. The low ceilings will become more widespread later tonight once the rain begins. Once in place, the IFR/MVFR conditions will linger into tomorrow. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........Skowronski SHORT TERM.....Allen LONG TERM......RDM AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Grand Rapids MI
951 PM EDT FRI SEP 9 2016 LATEST UPDATE... Update .SYNOPSIS... Issued at 330 PM EDT Fri Sep 9 2016 A low pressure system will bring showers and thunderstorms late tonight through midday Saturday. A cooler and drier airmass will move in behind this system for Saturday night through Monday as fair weather returns as high pressure builds in. Another low pressure system will bring a chance of showers and thunderstorms Tuesday with cooler temperatures to follow for mid to late next week. && .UPDATE... Issued at 951 PM EDT Fri Sep 9 2016 High pops warranted overnight southeast of GRR as all guidance shows slug of convection to our south moving into south central and southeast lwr MI overnight. This precip is associated with the low level jet and may contain some locally heavy rainfall as well as a low risk of svr wx. The issue with the severe weather threat is overall lack of instability, but considering the high shear it may only take a few hundred joules of ML Cape to make things interesting overnight. Latest RUC solutions indicate a sfc low developing over NW Indiana after midnight then deepening as it tracks northeast across south cntl lwr mi overnight, then into the thumb area of lwr mi by mid morning Saturday. Strengthening sfc wmfnt extending east from this low will result in very high low level shear values around JXN, with 0-1KM Helicity values of 200-300 m2/s2. This supports a tornado potential southeast of GRR roughly 4am-8am, but again, available sfc based instability is very much in question - especially at that time of night. && .SHORT TERM...(This evening through Sunday night) Issued at 330 PM EDT Fri Sep 9 2016 Our primary short term fcst concerns involve determining convective potential for late tonight through around 18Z Saturday. Fair wx will continue through late this afternoon. Rgnl radar trends show showers over northern IL/IN and scattered showers should begin to develop over our southern fcst area this evening as elevated instability begins to increase a bit to the north of the quasi stationary frontal boundary near the MI/IN border. Scattered convection will develop very late tonight with the approach of the strengthening sfc low and cold front. The severe wx threat very late tonight through 18Z Saturday is low given unfavorable frontal timing and relatively weak instability. However we still cannot rule out potential for isolated strong to severe storms Saturday morning through around 18Z Saturday given strong shear and upper level dynamics/pva in conjunction with forcing from the front and ample low level moisture. It does seem though that given the timing of the system that the much better chance for severe wx tomorrow will be east to southeast of our area across SE lwr MI and OH. Breezy conditions will develop Saturday afternoon and the strong west winds will quickly advect a cooler and drier airmass into our area. Fair weather will return late tomorrow through Sunday night as high pressure builds in. .LONG TERM...(Monday through Friday) Issued at 330 PM EDT Fri Sep 9 2016 The big story to me is the colder temperature behind the cold front Wednesday into Friday. It would not be out of the question there could be some patchy frost in our NE counties Thursday morning. Beyond that there is convection wednesday that is associated with the cold front. This does not seem like a big deal actually. Many areas may not even see rain from this front. We continue to see a progressive upper air pattern this week. The next system is currently a closed upper low in the Gulf of Alaska. It tracks eastward and opens up as it crosses the Canadian Rockies but thanks to a building subtropical high this system does not get as far south (jet core). So that means the best dynamics go north of our area. This suggest to me the threat for convection is more limited with this next system. In fact the most unstable cape is mostly under 500 j/kg. Many areas may not even see rain from this system. Even so with Lake Michigan as warm as it is, water spouts may be possible. One other aspect of this is with the jet core north we should not have a lot of low clouds once we get into the cold air, which means we could see temperatures fall into the 30s in our NE CWA. That could mean some patchy frost. With upper ridging developing this cool weather will not not last all that long, there will be a warming trend into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 758 PM EDT Fri Sep 9 2016 Initially as scattered showers spread in from the south this evening conditions will remain VFR. However look for a rapid transition to IFR after midnight as more widespread rain develops with the approaching low level jet. Tstms with heavy rainfall are also expected after midnight, particularly south and east of Grand Rapids. Passage of the cold front Saturday morning should lead to ceilings improving from IFR to MVFR, although intermittent showers and MVFR conditions will probably linger most of the day since the mid level trough does not come through until around or after 00z Sunday. South winds under 10 knots tonight will shift to the west on Saturday morning with the passage of the cold front, then increase to 10 to 20 kts in the afternoon, with some higher gusts closer to lk MI. && .MARINE... Issued at 330 PM EDT Fri Sep 9 2016 Will hoist a small craft advisory from St. Joseph to Manistee from 14Z Saturday through Saturday night as west winds will ramp up significantly to 15 to 25 kts with gusts to around 30 kts Saturday afternoon. This will cause wave heights to build to 4 to 7 feet. A beach hazards statement is also in effect from St. Joseph to Manistee Saturday through Saturday night. && .HYDROLOGY... Issued at 330 PM EDT Fri Sep 9 2016 Rivers are falling after the recent heavy rainfall. Showers and storms are expected late Friday night into Saturday afternoon. Less than a half inch of precipitation is expected across the area with locally heavy rain possible. River rises are possible, and some smaller rivers and streams may rise to near bankfull by Saturday night. && .GRR Watches/Warnings/Advisories... MI...Beach Hazards Statement from Saturday morning through Sunday morning for MIZ037-043-050-056-064-071. LM...Small Craft Advisory from 10 AM Saturday to 8 AM EDT Sunday for LMZ844>849. && $$ UPDATE...Meade SYNOPSIS...Laurens SHORT TERM...Laurens LONG TERM...WDM AVIATION...Meade HYDROLOGY...63 MARINE...Laurens
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1021 PM EDT FRI SEP 9 2016 .SYNOPSIS... High pressure overhead tonight will bring quiet weather for tonight before a warm front lifting north through the region on Saturday will bring the chance for showers and potentially a rumble of thunder. A strong cold front will move through the region late Saturday night and Sunday with a round of showers and thunderstorms expected. High pressure will build into the area for early next week with mild temperatures and dry conditions. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1020 PM Update... Quiet and dry night across northern New Hampshire with only a few clouds along the coast. These are moving east quickly and tonight should be mostly clear. Fog is likely in mountain valleys and have added mostly cloudy to the sky grids for this reason. HRRR still showing showers moving in as early as 7 AM in southwest NH as the warm front appproaches. This seems on track with dew points in the mid 60s in place already. Adjusted forecast for latest miso/mesoscale data...but no other changes at this time. 645 PM Update... A cold front has moved offshore and northerly winds are gusting into the lower 20 mph range at a few locations. Have updated temperatures, dew points, and winds to account for these details. Fog will once again develop tonight once winds decouple...but this time should be confined mainly to the CT River valley. Have added fog to the gridded forecast to reflect this thinking. Previous discussion... High Impact Weather Potential: Minimal. Current Pattern: Broad west southwest flow across the region today with the flow aloft just beginning to start to back as impressive early September trough digs into the central portion of the country. Drilling down to the surface...the weak front responsible for some showers overnight has now passed offshore...with subsidence/drier air aloft evident on early afternoon visible satellite imagery... with this drier air gradually mixing down to the surface. Certainly no cool air behind the front...with many locations over the southern half of the CWA sitting around the 90 degree mark. Very quiet weather through the near term as weak high pressure ridge axis settles overhead briefly before we await today/s front /now stalling south of the region/ to begin to return north by daybreak Saturday. Through Early Evening: Hot and somewhat humid with diurnal CU fading as we lose daytime heating this evening. Temperatures will start to fall fairly rapidly this evening given the drier airmass...but given how warm it is now...expect temperatures to remain mostly in the 70s through 8pm. Tonight: Weak area of high pressure west of the region settles overhead during the overnight period with core of dry wedge /PWATS near 0.75"/ centered over northern New England. This promises a mostly clear start to the night...with little sensible weather outside of some valley fog potential. Mid and upper level cloudiness will begin to increase over our far southern zones towards daybreak as lift on the 305-310K surfaces begins to spread north. We should remain dry through 6am. Wide ranging lows...with values in southern NH likely not to fall much lower than the mid/upper 60s given increasing cloud cover...with middle 50s/lower 60s further north in clearer airmass. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... High Impact Weather Potential: Heavy rain potential with thunderstorms Saturday night. Pattern: Upstream shortwave over the upper Midwest will become neutrally-tilted on Saturday...with low pressure taking shape over the northern Great Lakes and lifting north and east. This shortwave will be progressive...gaining a slightly negative tilt by Saturday Night and Sunday as it pushes through the region. While the aforementioned surface low will pass well north of New England through this period...our eyes will be first on a northward-lifting warm front for the day on Saturday...followed by a potent cold front on Saturday night. Saturday: There is increasing agreement in at least some precipitation development along the northward advancing warm front on Saturday...coming more in line with recent ECMWF runs. Ample moisture south of this boundary with PWATs +2-3 sigma /1.75"/ streaming north during the day. Deepest moisture and strongest pressure advection on the 310-315K surfaces will be over my western zones...and will paint the best PoPs here. Elevated instability is rather meager...but a few rumbles can/t be ruled out with this activity. Otherwise...increasing clouds for all areas...and with a developing southeasterly flow...expect temperatures well below today/s values...generally in the 70s...which agrees well with a multi-model consensus. Saturday Night: Low pressure tracks from just north of Georgian Bay 00Z Saturday northeast through central/northern Quebec dragging a cold front into my western zones by daybreak Sunday. Dynamics are impressive...with H5 jet streak nearing 100kt ahead of negatively tilted shortwave...with 125kt jet streak on the 1.5 PVU surface in the same general location...placing our area in the right entrance region after midnight. The overall trend has been to slow the arrival of the front...so can foresee a lull in the shower activity Saturday evening through the very early morning hours Sunday before the front nears from the west. Given the impressive dynamics...likely PoPs are in order...save the far southeastern zones...where the front will arrive later /after this forecast period ends/. With PWATs near 2" right along the front...and warm cloud depths up over 12kft...locally heavy rain will be the most likely hazard with pretty modest MUCAPE /given the time of day/ suggesting limited severe potential... although locally strong winds will be possible away from the stabilizing coastal influence. Another mild night in store...and temperatures may actually rise given the strong southerly low level jet ahead of the front...with 60s /and perhaps lower 70s south/ expected. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... The long term period starting right off the bat 12z Sunday will feature a strong cold front approaching or crossing the western portion of the CWA. Ahead of the front a moist airmass will be in place characterized by PWAT values in excess of 1.75 inches and showalter indices -2C or even a little lower. Forcing for ascent will likely be pretty strong with the front given the favorable positioning of the RRQ of a jet streak and PVA in association with an approaching vorticity max. The result will likely be a line of showers and thunderstorms crossing the CWA during the morning hours. The main threats will be brief torrential downpours, cloud to ground lightning, and brief gusty winds. It is not out of the question that an isolated strong/severe storm occurs, especially if a strong inversion is not in place at the SFC. The front will sweep offshore by early afternoon with rapid drying and clearing. Westerly winds will gust up to 30 mph during the afternoon hours in the wake of the front in the strong CAA regime. High pressure then builds in Sunday night and crests over New England on Monday with fair weather and chilly overnight temps. A warming trend will take shape late Monday and Tuesday as the high slips to the south of New England and another cold front approaches from the north. This front should slip through our area Tuesday night or Wednesday and could potentially bring a decent cool shot. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Short Term... Summary: High pressure will bring good flying conditions through tonight before a warm front lifts through the region Saturday bringing the potential for showers and thunderstorms...which will continue through Saturday night as a strong cold front approaches from the west. Restrictions: VFR will dominate the valid TAF period outside of LIFR/IFR fog at HIE/LEB after 08Z with some potential for fog at RKD as well. Conditions will deteriorate Saturday afternoon with widespread MVFR/IFR conditions Saturday night in showers...embedded thunderstorms and fog. Winds: Northwest winds 10kts will become light/variable overnight before shifting southeasterly 5-10kts for the day on Saturday...and then shifting southerly Saturday night. LLWS: No LLWS through Saturday...but llevel winds will strengthen markedly Saturday night with a period of LLWS likely. Thunder: Can/t rule out an isolated thunderstorm by Saturday afternoon...with embedded thunderstorms more likely Saturday night. Long Term...IFR conditions will be possible Sunday morning in low clouds, patchy fog, as well as showers and thunderstorms. Conditions rapidly go VFR midday Sunday and last into Tuesday with the passage of a cold front. Gusty westerly SFC winds to 25-30 KT possible Sunday afternoon && .MARINE... Short Term...High pressure crests over the region tonight...with light northeasterly winds expected. Winds shift southeasterly Saturday and then strengthen from the south ahead of a strong approaching cold front Saturday night. This will result in winds/waves nearing SCA levels overnight. Long Term...SCA`s will likely be needed Sunday in the wake of a cold front for gusts around 25 if not 30 kt. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Hanes SHORT TERM...Arnott LONG TERM...Ekster
Area Forecast Discussion
National Weather Service Indianapolis IN
1014 PM EDT FRI SEP 9 2016 .UPDATE... Aviation sections updated && .SYNOPSIS... Issued at 339 AM EDT Fri Sep 9 2016 An upper disturbance over Missouri will bring numerous showers and thunderstorms tonight as it moves our way. More showers and a few storms will occur Saturday as a cold front moves through. The rest of the weekend through early next week will be dry as high pressure moves east across our region. Another cold front will bring a chance of storms around mid week and another weak system may bring a slight chance of a few thundershowers towards Friday. && .NEAR TERM /Rest of Tonight/... Issued at 953 PM EDT Fri Sep 9 2016 Active evening in progress as scattered severe convection moves slowly east across the western forecast area. Beginning to see convection expand in coverage as well as a 40kt low level jet noses into the region and enhances low level forcing. Temps remained in the 70s and low 80s with muggy conditions persisting. First issue focuses on ongoing convection and the tornado risk in play as these storms continue to move into an airmass favorable for rotators. Have received a few reports of rotation but no tornadoes over the forecast area at this point in time. The elevated risk will remain at least for the next few hours as current mesoanalysis shows an axis of 0-1km helicities of 200-300m2/s2 tracking E/NE across central Indiana through about 05Z. With a small area of enhanced boundary layer shear aiding convection as well and the remnant outflow boundary promoting low level veering flow...potential for rotating storms and isolated tornadoes will continue. With that being said...the slowly diminishing MLCAPEs and poor lapse rates over the area are likely mitigating storms from being more intense and limiting the overall tornado threat. Will continue to monitor closely over the next few hours. The bigger issue from storms will gradually become heavy rain and localized flooding with precip water values back up over 2 inches and the low level jet serving to fuel expanding storm coverage through 06Z...with perhaps a brief lull during the predawn hours before renewed convection developing over the mid Mississippi Valley spreads into the region from the west towards daybreak. Will maintain high pops through the night. Zone and grid updates out. && .SHORT TERM /Saturday through Monday/... Issued at 320 PM EDT Fri Sep 9 2016 Main focus will be on rain chances Saturday as a cold front moves through our region. Models indicate another round of showers and storms may spread in towards morning and will go with likely POPS central and southeast Saturday. Models move the cold front through by early Saturday afternoon and showers and and storms will probably end over western sections by mid afternoon and elsewhere by late afternoon. SPC has areas just east of us in a slight risk of severe Saturday. The rest of the weekend and early next week will be dry as high pressure behind the cold front moves our way by late Sunday and to southern New England Monday. Model soundings indicate a very dry airmass. Went with a MOS blend on temperatures most periods...but tweaked highs slightly warmer by Monday with lots of sunshine and warm advection. Anyways highs will be in the upper 70s to lower 80s Saturday...middle 70s Sunday and upper 70s to around 80 Monday. Lows will be in the lower to middle 50s both nights. && .LONG TERM /Monday Night Through Friday/... Issued at 224 PM EDT Fri Sep 9 2016 Models are close enough that the SuperBlend initialization was accepted for most items. An upper trough will bring a cold front through the area mid week, bringing rain chances at that time. By late week, an upper ridge will be developing overhead, but at the surface an inverted trough will also develop. Am not confident about the low PoPs Friday, but with the trough nearby do not feel comfortable removing Superblend`s PoPs. Temperatures will be near to above average for most of the period. && .AVIATION /Discussion for the 100300 IND Taf Update/... Brief MVFR conditions will be possible in the next 90-120 minutes as TSRA just west of the IND taf site...as seen on current radar...are expected to push across the area. After these storms pass after 03z-04z...a return to VFR is expected. Previous Discussion Below /Discussion for the 100000 tafs/... Issued at 647 PM EDT Fri Sep 9 2016 VFR conditions will exist for a brief time initially at most taf sites. Thunderstorms are expected to impact the TAF sites through 06Z. Any thunderstorm may produce brief MVFR/IFR conditions. HRRR suggests continued development of TSRA over Illinois and propagation across the taf sites through 06Z. Warm and moist air mass remains in place across the area and Thunderstorms development to the west is ongoing. Thus have trended toward TSRA this evening to account for these features. HRRR suggest Storms should diminish...end and exit by 06z...and time heights show a loss of forcing aft 06z. Thus have ended the TSRA chcs by that time. Cold front is then expected to push across the forecast area during the morning hours on Saturday. This will lead to More shra and possibly some TSRA producing MVFR CIGs as they pass on Saturday morning. Better flying conditions and a return to VFR is expected after 21-23z on Saturday as the front departs the area and High pressure arrives in Central Indiana. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...JH NEAR TERM...RYAN SHORT TERM...JH LONG TERM....50 AVIATION...JP
Area Forecast Discussion
National Weather Service Northern Indiana
726 PM EDT FRI SEP 9 2016 .SYNOPSIS... Issued at 349 PM EDT Fri Sep 9 2016 Showers and thunderstorms are expected tonight ahead of a warm front. Locally heavy rain is possible along with the potential for strong to severe storms. Lows will be in the middle 60s. A cold front will sweep across the area on Saturday with additional chances for showers and thunderstorms...mainly along and east of Interstate 69. && .SHORT TERM...(This Evening through Saturday) Issued at 349 PM EDT Fri Sep 9 2016 Focus of forecast on this evening with increasing concerns for at least 1 round of widespread rain, with embedded storms both in and on back edge of the rain. Radar currently showing returns over the SW parts of the area struggling to reach the ground as any moisture goes to saturation of a large EML as reflected on 12z ILX sounding. Attention will shift more to the southwest where 2 features of interest reside. The first is the effective surface warm front located from northeast of St Louis to across the Ohio River. The second is the remnants of Hurricane Newton work into the region tonight with surface low pressure developing somewhere between Chicago and Ft Wayne. These 2 features will help bring the following elements in 1) Tropical moisture with PWATS in excess of 2 inches resulting in efficient rain producers 2) Increase in low level jet to 40 kts or more resulting in pockets of increased bulk shear 3) 0- 1 km Helicity increasing to potentially 100 to 200 m2/s2. HRRR has been fairly consistent in area of rain/embedded storms taking shape SW of the area and moving in near/just after 00z. SWOMCD just issued highlighting this threat with potential for watch out to our SW shortly. Have adjusted pop trends faster with cat pops across the area by late evening. Mention of heavy rain added to grids tonight but no hydro headlines as convection should be progressive. This doesn`t eliminate any threat for brief training/redevelopment from boundary interactions. Everything may exit the area after 6z with potential for a lull until the cold front approaches from the NW Saturday. At the present time it appears that locations around and east of I-69 stand the best chance for shower/storm redevelopment with trends increasing as they leave the forecast area. Only minor changes for the time being given greater focus on this evening. && .LONG TERM...(Saturday Night through Friday) Issued at 349 PM EDT Fri Sep 9 2016 Few changes to long term given potential short term weather concerns and overall lack of sensible weather issues outside Tuesday/Tuesday night. Longwave trough will dig into the western states with a piece of it breaking off and heading east across the northern Lakes to bring a chance of showers/storms. Otherwise high pressure should dominate conditions before and after this feature with seasonable temperatures. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) Issued at 726 PM EDT Fri Sep 9 2016 Sfc cyclone over ern IA will lift northeast into wrn lower MI by daybreak Sat. Warm front extending eastward through cntrl IN/IL will mix northward ahead of this system, yielding a period of shra/ts from late evening through early morning. Thus expect a general deterioration in flight conditions will result later this evening as burgeoning area of rainfall upstream through ern/ne IL spreads east across the terminals 03-05Z. Thereafter prevailing mvfr/occasional ifr conditions expected to persist through mid morning Sat. Additional shra/ts likely to develop along/ahead of eastward progressing cold front Sat aftn. However disparate model based convective scenarios and timing uncertainties preclude specific mention at this point. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement from Saturday morning through Sunday morning for INZ003. MI...Beach Hazards Statement from Saturday morning through Sunday morning for MIZ077. OH...NONE. LM...Small Craft Advisory from 10 AM Saturday to 8 AM EDT Sunday for LMZ043-046. && $$ SYNOPSIS...Fisher SHORT TERM...Fisher LONG TERM...Fisher AVIATION...T 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 Jackson KY
1007 PM EDT Fri Sep 9 2016 .UPDATE... Issued at 1007 PM EDT FRI SEP 9 2016 Have removed all precip from the forecast area during the overnight period and therefore updated the HWO to reflect this change. Also freshened up the sky cover and hourly temps. Sent updates to NDFD and web servers. UPDATE Issued at 704 PM EDT FRI SEP 9 2016 Recent radar imagery shows that the afternoon showers have exited the forecast area. There are a few additional showers popping up in north-central KY so cannot rule out a rogue shower or two in the far north over the next few hours. Beyond that, the area should stay dry overnight. Also backed off on sky cover as most of the afternoon cu has dissipated. Did a quick refresh to the hourly temps to reflect most recent obs and sent updates to NDFD and web servers. UPDATE Issued at 433 PM EDT FRI SEP 9 2016 Reloaded the full set of grids with the Shortblend and Superblend after taking operations back from RLX. From these blends, updated pops and temperatures in the near term per recent radar imagery and obs, respectively. && .SHORT TERM...(This evening through Saturday night) Issued at 300 PM EDT FRI SEP 9 2016 18z sfc analysis shows an old boundary north of the Ohio River with low pressure and cold front approaching from the northwest. High pressure has held on across the south today keeping the weather quiet, rather sunny, warm, and humid there. To the north, though, a lingering cluster of light showers has held together as it moved slowly east into the CWA but also did not develop much further despite the relatively unstable and high PW airmass. In fact, the thicker clouds from this area of showers likely kept anything of note from developing by suppressing the sfc based instability. Due to the dichotomy of the clouds today, temperatures varied from upper 70s to low 80s north to the upper 80s and low 90s south. Mid 80s were mostly found through the middle part of the CWA. Do still expect temps to rebound in the north over the next couple of hours. Dewpoints, meanwhile, also varied geographically from around 70 degrees north to the low to mid 60s south. Southwest winds of around 10 mph and, at times, gusting to between 10 and 20 mph kept the sticky air moving for most places. The models are in good agreement aloft through the short term portion of the forecast as they all depict a decent shortwave trough crossing the Ohio Valley late Saturday into early Sunday morning. The extent of the energy associated with this feature will brush through northern Kentucky and likely help to generate storms for our area later Saturday. Heights will then flatten out in its wake leading into Sunday morning. Given the good model agreement will favor a blended solution with a lean toward the HRRR for near term specifics and the NAM12 beyond that. Sensible weather will feature a fairly quiet and warm/muggy evening with just a few showers or thunderstorms around, should things be able to develop in the next few hours. These will die out quickly following sunset with a quiet night on tap in the warm sector awaiting the approaching cold front. Any fog overnight should be confined to the deeper valleys, unless we see more shower activity than anticipated late this afternoon and evening. For Saturday, another warm day will lead into an afternoon of better instability and potential for strong to severe storms. The cold front bringing in good sfc convergence will arrive sometime after 21z and be accompanied by good upper level support in addition to rather high PW air. There will be a threat for damaging winds with the strongest of the storms, in addition to heavy rains, into the evening. The front and convection clears off later that night with cooler and drier air pushing in behind. Made only minor adjustments to the temperature grids for terrain distinctions tonight and Saturday night...though with opposite effects - typical ridge/valley tonight and a more CAA pattern tomorrow night. As for PoPs, ended up close to MOS with the fropa on Saturday and minimized them outside of that time. .LONG TERM...(Sunday through Friday) Issued at 331 PM EDT FRI SEP 9 2016 Overall, a quiet period typical of this time of year is in store, with models in agreement. A cold front will be exiting southeast of the region early Sunday. High pressure behind the front will pass by to our north under fairly zonal flow, and bring fair weather through midweek. The air mass will be seasonably dry, allowing for some cooler night time temps, especially in valleys. An upper trough dropping southeast over New England will allow a cold front to trail southeast through our area on Wednesday and Wednesday evening. Moisture will be limited, and getting pinched off as the front sinks southeast. Only 20% POPs have been used in the northern part of the area. Behind this, another surface high will pass by to our north and northeast. The heart of the cooler and drier air associated with the high will miss us, but we may at least be glanced by the air mass. As the high passes to our east, moisture will start to make more of a comeback on return flow from the south on Friday. Can not rule out some showers/storms with this, but ridging aloft and a lack of features will probably keep it very limited. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 755 PM EDT FRI SEP 9 2016 VFR conditions should prevail through most of the period as a cold front approaches the region tomorrow afternoon. Overnight, some fog is possible in the valleys, but this will likely not impact any TAF sites with the exception of SJS which received some brief rainfall today. Clouds will gradually thicken and lower throughout the day tomorrow but should remain MVFR or above. Showers and thunderstorms will be possible along and ahead of the front which is expected to enter the region after 19Z. Some of these storms could bring lower visibilities and gusty winds to the TAF sites towards the end of the period and beyond. Winds will remain light and variable overnight, then become gusty during the afternoon and evening hours tomorrow. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JVM SHORT TERM...GREIF LONG TERM...HAL AVIATION...JVM
Area Forecast Discussion
National Weather Service Miami FL
748 PM EDT FRI SEP 9 2016 .UPDATE... Current radar returns indicate widely dispersed showers and isolated thunderstorms mainly across the Atlantic waters with occasional activity affecting the Atlantic metro areas as they pass westward. This is reflected in the current forecast with no update necessary. The weak low in the Florida Straits continues to move to the west southwest. The Key West radar clearly indicates a low level circulation. So far the suite of model guidance is on track indicating the west southwest movement over the Straits. 60 && .PREV DISCUSSION... /issued 728 PM EDT FRI SEP 9 2016/ AVIATION... VFR conditions should prevail, although brief periods of MVFR CIGS and vsby restrictions are possible near showers and isolated thunderstorms. Light easterly flow tonight will increase to 10-15 knots Saturday. Generally, only isolated thunderstorms expected, but coverage could increase by Saturday afternoon, so VCTS introduced at that point. PREV DISCUSSION... /issued 514 PM EDT FRI SEP 9 2016/ DISCUSSION... For the short term, the major synoptic feature is a weak area of low pressure across the Florida Straits. The local LAPS analysis indicated a weak closed low at 19z and for the last 3 to 4 hours has indicated an increasing trend in the surface vorticity. This is consistent with recent visible satellite imagery indicating a low level swirl with active convection to the southeast. The forecast for tonight...The general consensus of the global models and the latest HRRR model as well indicate a general west to southwest movement of the weak surface low across the Florida Straits tonight, with recent model guidance consensus indicating it could be to the southwest of the Florida Keys on Saturday morning. Regarding any potential for possible tropical formation, please monitor and consult the products of the National Hurricane Center. As for any impacts on South Florida as it tracks west to southwest tonight, expecting bands of showers and isolated thunderstorms to continue radiating outward from the low and mainly impacting the southern portion of the peninsula and the adjacent Gulf and Atlantic waters. With the passage of bands of showers, brief heavy downpours and gusty winds can be expected. For any marine impacts, consult the marine discussion below. Forecast for Saturday and Sunday... If the aforementioned low continues to track westward as indicated above, this will result in deep moisture across the region in its wake with chances of showers and thunderstorms over the weekend. An upper level low currently east of the Carolinas will likely continue to retrograde southwest over the weekend and will enhance chances of showers and thunderstorms, with activity possible across the Gulf and Atlantic waters as well. Forecast for early next week... A weak trough currently east of Puerto Rico is forecast to continue on a northwest track the next couple of days and is forecast to be near the central to northwest Bahamas by Monday with an increase in moisture and chances of showers and thunderstorms across the region. Deep moisture and regional showers and thunderstorms could linger into mid-week. MARINE... The most recent ASCAT pass at 1605Z indicated winds to near 20 knots or just above in the off shore waters mainly east of Biscayne Bay. Some of the wind data may be rain contaminated and some of it is on the western fringe of the pass where there is some additional uncertainty. The wind forecast for this afternoon and evening for the off shore waters east of Biscayne Bay is in the 17 to 20 knot range, which could extend into Biscayne Bay as well, and will continue with a pre-cautionary statement and do not think a Small Craft Advisory will be necessary. Later tonight winds in the off shore Gulf waters may near the 15 to 20 knot range as well with a pre-cautionary statement in effect. The weak surface low is forecast to drift westward tonight into Saturday and the pressure gradient and winds will slowly weaken into Saturday morning. For the remainder of the weekend winds and seas will be well below any advisory or pre-cautionary statement criteria. BEACH FORECAST... With the increased winds this afternoon across the coastal zone of Miami Dade and Broward counties the rip current risk was increased to a high risk for these counties and could persist through the early morning hours on Saturday then decrease to a more moderate risk as easterly winds continue to slowly subside through Saturday. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 78 90 79 89 / 30 40 40 50 Fort Lauderdale 80 89 79 89 / 40 40 30 50 Miami 78 90 78 90 / 50 50 40 50 Naples 77 92 76 91 / 20 50 30 50 && .MFL Watches/Warnings/Advisories... FL...High Rip Current Risk until midnight EDT tonight for FLZ172-173. AM...None. GM...None. && $$ UPDATE...60/BD
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1020 PM CDT FRI SEP 9 2016 .UPDATE...For 06z Aviation discussion below && .SHORT TERM...(This evening through Saturday) Issued at 324 PM CDT Fri Sep 9 2016 Unorganized low pressure at the surface developing across Iowa is expected to finally take shape and move northeast through Wisconsin tonight. Meanwhile a deep trough is in the process of digging and compacting aloft with its axis through the western Dakotas this afternoon. For the remainder of the afternoon, the HRRR is on track with an area of showers and thunderstorms advancing northeast out of Iowa through south central MN and will continue northeast over the next several hours, exiting our forecast area around 01-02Z. The trough axis will continue east tonight and be centered over Minnesota by tomorrow morning. Low level cold air advection will progress eastward overnight as that boundary continued its advance and that surface low moves off to out east. Isolated showers are possible overnight thanks to the advancing trough. Tomorrow will be cooler and feel and look more like fall with breezy northwest winds, lower dewpoints, and stubborn cloud cover that could linger through the day in western WI and parts of eastern MN. Expecting a broken cumulus field to develop given strong CAA and saturation at the top of the channel during the day. The RAP has been steadfast in working spits of rain and showers through under the center of the trough as well. Eventually, low level anticyclonic flow on the backside of the upper trough should help clouds start scattering out from west to east. Most locations will top out in the upper 60s tomorrow and low 70s in western MN where less cloud cover is expected. .LONG TERM...(Saturday night through Friday) Issued at 324 PM CDT Fri Sep 9 2016 High pressure will be firmly overhead at the start of the long term, then drift off to the lower Great Lakes through Monday. Lows Saturday night will be more fall like with middle 40s to lower 50s. However, the cooler temperatures won`t last long as we transition to the backside of the high for Sunday with afternoon highs in the middle 70s to lower 80s. Good continuity remains between the GFS and EC with regards to the passage of a cold front across the area from late Monday into early Tuesday. Neither model is showing much precipitation as the bulk of the forcing is north of us in Ontario. Therefore, small chance pops continue, mainly for the eastern and southern FA. Another large high pressure system will build in for late Tuesday into Thursday with pleasant early fall-like weather conditions. Highs Tuesday and Wednesday will only be in the 60s, some 5 to 8 degrees below normal. Wednesday morning will be quite cool with lows in the upper 30s to middle 40s. As it was pointed out in the overnight AFD, the last time MSP has had a low below 50 degrees was May 18th. If the low below 50 degrees occurs, this would end our streak of days where the temperature has remained 50 or greater at 118 days, which would be the second longest such stretch behind only the 124 days from the summer of 1881. Weather conditions will begin to deteriorate on Friday and persist through the weekend as a closed upper low in the northern Rockies begins to open up and advance into the Northern Plains. Chance pops are in place now, but they will likely trend higher as we get closer to the event and continuity is established. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1020 PM CDT Fri Sep 9 2016 A few sprinkles or light showers will be possible overnight as a weak trough moves over central MN. Have included VCSH mentions at KAXN/KSTC overnight, and at KRNH/KEAU around daybreak and a few hours after. The latter sites over west central WI will also be more susceptible to MVFR cig development overnight and early Saturday. Cumulus clouds will develop on Saturday (highest coverage from eastern MN into western WI). Northwest winds will prevail behind the front with gusts to around 20 kts developing by late morning. KMSP... Any showers that develop over central MN are anticipated to fizzle by the time they would reach KMSP. Otherwise, the period will consist of sct-bkn low-end VFR. Prevalent northwest winds behind the front with gusts to around 20 kts developing by 17z. /OUTLOOK FOR KMSP/ Sun...VFR. Wind S at 10-15 kts. Mon...VFR. Wind SW 5-10 kts turning NW. Tue...VFR. Wind N 5-10 kts. && .MPX Watches/Warnings/Advisories... WI...None. MN...None. && $$ SHORT TERM...SPD LONG TERM...RAH AVIATION...LS
Area Forecast Discussion
National Weather Service Mount Holly NJ
926 PM EDT FRI SEP 9 2016 .SYNOPSIS... A weak cold front continues to push through Central New York and Pennsylvania through the overnight. It will then return north as a warm front into New York State on Saturday. A stronger cold front will move east through the mid Atlantic states late Saturday night. High pressure then will build eastward into the region early next week. Another cold front will cross the mid Atlantic states late Wednesday, followed by Great Lakes high pressure for the end of the week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Showers have moved out of the local area, and dry conditions on tap through around midnight. Another cluster of showers and thunderstorms has developed over western MD and is tracking to the NE into central PA. Due to the warm temps and high dewpoints, there is a fair amount of CAPE across the region, generally on the order of 500-1000 J/kg of SB CAPE, but the atmosphere is capped as well, with 50-100 J/kg of SB CIN. Will be hard for those storms to maintain in this environment, but the HRRR continues to have those showers and possible storms tracking into the Lehigh Valley and Pocono Mountains sometime between 06-10Z. Given how capped the atmosphere is, and given how humid the airmass is with sfc dewpoints well into the 70s, think that showers are possible across PA, possibly into western NJ, but not as confident on the thunder. Will run with chance PoPs for western zones, mainly after midnight and into daybreak. Otherwise, warm and muggy night with lows in the upper 70s in/around Philly, and into MD and DE. Otherwise, lows will be in the low to mid 70s, which is a few degrees cooler than last night. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... No significant changes to the forecast for Saturday. Hot and humid with near record temps once again. Based on latest forecast trends, possible for showers and thunderstorms by midday into the Poconos, but low confidence on convection anywhere else until towards evening. For highs, used a 50 50 blend of the 12z/9 gfs/nam mos. The cool temp (climo impacted as well) bias resulted in our forecasting temps a bit warmer than guidance and may not have warmed it enough with 20c overhead. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Sat night and early Sunday...A cold front will cross the area this period. The hot and humid airmass will yield to much drier and somewhat cooler air for the last part of the weekend. Temperatures Sunday will still be above normal, with low 80s north and mid 80s south/east. Winds Sunday will be a bit gusty with NW breezes at 12- 18 mph during the afternoon. Sunday afternoon thru Tuesday night...A dry period with high pressure building in. Temperatures will be normal Mon and above normal for Tue with readings in the low/mid 80s Tue. We could end up being a bit warmer Tue/Tue night if present trends in model guidance continue. Wed/Wed night...Another cold front is expected to cross the area. We have continued with the chc pops for a tstm on Wed and then taper back to slgt chc for Wed night. Thu/Fri...Temperatures back to normal, or slightly below with another high pressure system expected to build over the area. Dry weather is expected. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Mainly a VFR forecast with SCT-BKN clouds aoa 5000 ft. Few SHRA, possibly a TSRA could impact KABE/KRDG/KTTN from 05-08Z. Confidence too low to mention in the TAFs. Otherwise, light S winds. Patchy fog possible with brief MVFR VSBYs from around 09-12Z at KRDG/KABE/KTTN and possibly KMIV. Saturday...Mainly VFR with sct clouds aoa 5000 ft. Winds becoming SW 10-15 KT with gusts up to 20 KT after 18Z. Low confidence on convection at TAF sites until after 18Z. OUTLOOK... Saturday night and Sunday: Mainly VFR, Southwesterly winds shifting to west or northwesterly around 10-15 knots with higher gusts. Isolated showers and thunderstorms may lower ceilings and visibilities for brief intervals Saturday night. Sunday night through Tuesday: VFR, with winds 10 knots or less. Wednesday...Mostly VFR, but sct thunderstorms are possible. && .MARINE... Winds and seas should remain below SCA criteria through midday Saturday. SCA issued thereafter for the Atlantic waters and may need to add DE Bay in later forecasts. We could be several hours premature but thinking that sw winds in the increasing gradient should produce afternoon gusts to 25 kt on the near shore waters. OUTLOOK... A small craft advisory was been issued for the ocean zones through Sunday morning. This could be extended later in time Sunday as the cooler air arrives. Winds and seas will remain below SCA levels in Del bay. Sct tstms may create locally higher winds and seas. Sat night and early Sunday. Sun afternoon thru Wed...Mostly sub-sca conditions expected. A few tstms are possible later Wed. RIP CURRENTS... Saturday: The probable risk for the formation of dangerous rip currents is moderate. If S winds become stronger than forecast, earlier than forecast, in the afternoon, there is the possibility of a high risk for the formation of dangerous rip currents. && .CLIMATE... Heat (4-6 day heat wave) in progress as we go through this week. Heat wave count as of today: ILG 4 days; PHL ABE RDG 3 days, so far. 9/7: RER equaled at ABE. 9/8: RERGED and a RERTTN equal. 9/9: RERACY, GED, ILG, PHL (95) and TTN (94) so far today for max`s and for all 8 climate sites on the mins. rer`s will update by 545 PM. Here are the record high temperatures for Today and Saturday, the hottest days in this stretch. Friday- 9/9 Saturday 9/10 ACY 92-1915 95-1983 PHL 94-1884 97-1983 ILG 94-1939, 1915 98-1983 ABE 95-2015 96,1983 TTN 93-1959 101,1983 GED 92-2015,1985 93,1985 RDG 94-2015, 1959 100,1983 MPO 88-1964 89,1983 So far Philadelphia International Airport has recorded 43 days where the high temperature has gone over 90 degrees this is sixth all time. Several other years had more days over 90 degrees they include 2010 with 55 90 degree days and 1991 with 53 90 degree days. Additional years include 1995 and 1988 with 49 days over 90 degrees and 46 days back in 2002. A few more 90 degree days are still likely to occur this week, another 90 degree day possible next Wednesday. The table below for reference RER # 90 deg days: Season total, Season RER, Sept rer, Sept mean then closing out with Season rank and POR. You can see in the period of record (POR) that the number of 90 degree days this year will be top 5 in the detailed historical record, further supporting one of the warmest summers in the period of record. The 90 degree data below is through today - September 9. 2016 RER 9/RER 9/Mean Season rank POR ABE 36 41-1966 7-2015 1 #4 prob rise to #2-3 1922 ACY 31 46-2010 9-1961 1 #6 now could tie #4 1874 PHL 44 55-2010 8-1970 2 #5 1872 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Heat Advisory until 7 PM EDT Saturday for PAZ060>062-070-071- 101>106. NJ...Heat Advisory until 7 PM EDT Saturday for NJZ009-010-012-013- 015>023-027. DE...Heat Advisory until 7 PM EDT Saturday for DEZ001>003. MD...Heat Advisory until 7 PM EDT Saturday for MDZ008-012-015-019- 020. MARINE...Small Craft Advisory from noon Saturday to 5 AM EDT Sunday for ANZ450>455. && $$ Synopsis...O`Hara Near Term...MPS Short Term...Drag Long Term...O`Hara Aviation...Drag/MPS/O`Hara Marine...Drag/Gaines/O`Hara Climate...
Area Forecast Discussion
National Weather Service Shreveport LA
1042 PM CDT FRI SEP 9 2016 .AVIATION... Mostly vfr skc with a few low mvfr decks possibly returning nwd into area after 10/10z. some patchy fog also possible...but should be brief in nature...if at all. Outflow convection ahead of approaching cold frontal boundary may reach sw AR after 10/12z but will likely diminish before 10/18z. Isold to scattered convection may redevelop in aftn along and south of I-20. Kmlu and klfk may see convection continue beyond 11/00z with slow frontal movement across area. Mid lvl cloud decks may persist behind this weak frontal boundary, however skies to begin clearing over south AR after 11/00z./VII/. && PREV DISCUSSION... /issued 404 PM CDT FRI SEP 9 2016/ DISCUSSION... Sct convection has expanded across much of SE TX this afternoon...as well as portions of Deep E TX...with the convection more isolated over Wrn and Ncntrl LA and Union County AR. Evidently...the drier air to the E and N of the upper low just off the TX coast has really tapered development over Nrn LA...with the latest HRRR suggesting the convection diminishing by 01Z over these areas. Have maintained slight chance pops through early evening for these areas...with a mostly quiet night expected as warm and muggy conditions continue over the area. However...the afternoon water vapor imagery reveals an upper trough translating SE across the Nrn and Cntrl Rockies...which will absorb the weak upper troughing /the remnants of Newton/ over the TX Panhandle into NW OK/Cntrl KS/...allowing a weak cold front to shift SE into NW TX/Cntrl and Ern OK late tonight. A 25-30kt SSW LLJ is progged to develop over the Srn Plains ahead of the front later tonight...enhancing low level convergence and resulting in sct/numerous areas of convection development along/ahead of the front and attendant upper trough. The short term progs suggest that this convection will accelerate SE into Wrn AR/extreme SE OK/Ncntrl TX late tonight...reaching the far NW zones just prior to daybreak Saturday. Have maintained chance pops NW of I-30 tonight...with the progs maintaining this convection along a SE building mesoscale bndry through mid-morning Saturday before weakening as pre-frontal convergence weakens when the H925-850 winds quickly become WNW. This bndry will likely focus additional sct convection development with diurnal heating Saturday afternoon mainly over E TX/N LA near the I-20 corridor...with the bndry possibly hanging up over these areas. Meanwhile...the weak cold front itself will slowly drift SE into extreme NE TX/SW AR by mid to late morning...and should not focus much in the way of deep convection as the air mass should be stabilized with the earlier bndry passage/rain-cooled air. Given the weak forcing/shear and uncertainty of additional development for the afternoon...have lowered pops to mid and high chance Saturday afternoon...with the convection likely diminishing during the evening with the loss of heating/instability. The front itself remains progged to continue drifting S and becoming stationary Sunday over Cntrl LA/adjacent E TX...with the drier air lagging the front a ways to the N over SW AR Sunday morning before slowly mixing SSW for the afternoon. Sct convection should again redevelop near the old front Sunday mainly over SE and Deep E TX/Cntrl and Srn LA...with dry advection farther N inhibiting much development along the I-20 corridor. Should begin to see more comfortable temps during the morning mainly over SE OK/SW AR Saturday and especially Sunday nights...offering another brief tease of Fall for these areas. Additional drier air is progged to backdoor SW into Ncntrl LA Sunday night behind the old sfc bndry...with any convection possibly more isolated over our Srn counties and parishes. Meanwhile...the TX coastal upper low appears as if it will be absorbed in the weak troughing by Sunday...lingering near the SE TX/S LA coasts through Monday before ridging aloft builds and expands E across the Srn Plains and the Ark-La-Tex. Thus...a return to near to slightly above normal temps is expected by Monday through much of next week. ENE sfc winds behind weak sfc ridging appear to persist through much of next week...resulting in slightly cooler min temps through the period. Much of the week should remain dry beneath the upper ridge...although isolated convection can/t be ruled out mainly over the Srn and Wrn zones as the ridge begins to slowly nudge E into the Lower MS Valley. Prelims to follow below... 15 PREV DISCUSSION... /issued 1204 PM CDT FRI SEP 9 2016/ && .PRELIMINARY POINT TEMPS/POPS... SHV 75 91 70 88 / 10 50 20 20 MLU 74 92 71 87 / 10 40 30 30 DEQ 72 85 61 86 / 40 60 10 0 TXK 74 87 65 86 / 20 60 10 0 ELD 74 88 67 85 / 10 50 20 10 TYR 75 89 69 88 / 10 50 20 20 GGG 74 90 69 88 / 10 50 20 20 LFK 73 91 72 90 / 10 40 30 40 && .SHV Watches/Warnings/Advisories... AR...None. LA...None. OK...None. TX...None. && $$
For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php
Area Forecast Discussion
National Weather Service Bismarck ND
410 AM CDT Sat Sep 10 2016 .SHORT TERM...(Today and tonight) Issued at 410 AM CDT Sat Sep 10 2016 Correction issued for wording of possible frost on Tuesday morning in long term discussion. Included patchy fog for early this morning mainly northwest and northcentral, similar to HRRR and RAP solutions which indicate fog potential. So far, no reports of fog or indications on satellite fog product, but temp/dew point spreads are very low with clear skies and light winds. Otherwise, shortwave trough that supported showers and isolated thunderstorms into Friday evening will progress to the Great Lakes region today with upper level ridging building in over the Northern Plains today. This will result in a dry and mild day with highs in the upper 60s to low 70s. Will also see skies initially clear give way to increasing clouds during the day, especially north. On Saturday night and Sunday, upper level flow becomes more zonal then eventually southwesterly as long wave trough upstream begins to drop into the northwest CONUS. .LONG TERM...(Sunday through Friday) Issued at 410 AM CDT Sat Sep 10 2016 Low level southwest flow will result in warm temps on Sunday with highs in the 70s north to low/mid 80s south-central. A strong cold front will move into northwest ND by early afternoon Sunday, reaching the southeast part of the state by early evening. Models indicate a chance of some light showers. High temps on Monday will be 20 degrees cooler than Sunday with brisk northwest winds behind the front. Surface high pressure center drifts to western ND by 12z Tuesday, which will support the possibility of frost Tuesday morning. Upper level ridging again moves in until midweek, when closed upper low over Intermountain West begins to lift toward the Northern Plains with showers and thunderstorms possible beginning Thursday. Some timing differences exist between GFS and ECMWF, though overall agreement with the upper low drifting across ND late in the week. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1245 AM CDT Sat Sep 10 2016 VFR conditions expected. Some fog development possible toward daybreak across the north. Given uncertainty and only slight reductions in visibility from model guidance, have not included in the TAFs but will monitor and update as needed. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JNS LONG TERM...JNS AVIATION...JNS
Area Forecast Discussion
National Weather Service State College PA
554 AM EDT SAT SEP 10 2016 .SYNOPSIS... Low pressure will track northward through the Great Lakes today, pushing a trailing cold front through central Pa tonight. High pressure will build into Pennsylvania Sunday and remain over the state through early next week. A cold front will push south across the region Wednesday, followed by another high pressure system late in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Radar loop at 09Z showing a few lingering showers across northern Pa assoc with retreating warm front. Convection-allowing ensembles and latest HRRR support the chance of showers across the northern tier until arnd 12Z-14Z. IR imagery at 09Z already showing clearing skies across southern Pa and expect that trend to expand north later this morning, as the region breaks into the warm sector ahead of low pressure ovr the Grt Lks. Model soundings support a partly sunny and hot Saturday with readings by afternoon well into the 80s for most of the area and the low 90s in the Susq Valley. The combination of heat and dwpts near 70F should push apparent temps into the mid to upper 90s across the southeast counties. Potent mid lvl shortwave and assoc cold front will approach the region late today, bringing an increasing chance of showers/storms toward evening across the NW Mtns. Further east, scattered diurnally-driven, pulse-type convection is likely to develop across the eastern counties. Both the NCAR ensemble and SPC SSEO support this idea of sct afternoon shra/tsra across the central Mtns and Susq Valley. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Focus this evening will be on the potential of svr weather across the northwest counties with arrival of cold front. Convection- allowing models indicate a broken line of tsra will move into the NW Mtns around 00Z supported by strong, deep layer shear and modest instability. Expect a diminishing svr wx threat further east, with fropa occurring late at night across the central mtns and Susq Valley. SPC slight risk covers 6 of our northwest counties this evening. Cold front and assoc dwindling line of convection should be exiting the Lower Susq Valley by dawn Sunday. Arrival of high pressure and low PWAT air mass will bring clearing skies and much lower humidity Sunday with max temps close to seasonal levels. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Broad agreement among med range models for a period of fair weather early next week, as sfc high builds eastward across Pa. Although the accompanying air mass will be much drier, mdl 8h temps still indicate above normal temps, esp as southerly flow strengthens Tuesday ahead of next cold front. Scattered showers in the fcst for Wednesday with passage of cold front, then another stretch of fair weather/low humidity appears likely late in the week, as NAEFS/ECENS show high pressure building into the northeast states. && .AVIATION /10Z SATURDAY THROUGH WEDNESDAY/... A warm front near the NY/PA border will lift northward this morning. Low pressure will track northward through the Great Lakes today, pushing a trailing cold front through central Pa tonight. Isolated showers impacting the NE portion of CWA will move out of the area by sunrise. A line of showers/tstms lifting across Ohio/Lake Erie may catch the western part of Warren county, but will track west of BFD. IFR/MVFR restrictions that have developed in many areas overnight will hang tough through 14-16z (maybe even as late as 18z in a few spots) before improving to VFR. Light winds through midday will pick up from the SW to around 8-12mph with gusts to 14-22mph this afternoon. Isolated tstms may develop late this afternoon in hot/humid airmass with local impacts. As a cold front moves in from the west this evening, expect a potentially strong line of showers/tstms to impact the NW mtns around 00z. This line should weaken as it tracks eastward, but storms could be accompanied by locally gusty winds along its path through 06z. Cig restrictions expected behind the front tonight over the western mtns. Outlook... Sun...AM log cigs possible w mtns. Mon-Tue...No sig wx. Wed...Chc shra/tsra. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ Synopsis...Fitzgerald Near Term...Fitzgerald Short Term...Fitzgerald Long Term...Fitzgerald/Gartner Aviation...RXR
Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Sunday Issued at 254 AM CDT Sat Sep 10 2016 07Z surface analysis indicates low pressure over east-central Wisconsin, just northeast of Oshkosh, accompanied by N-S trof/cold front. Line of showers forming along trough and moving NE while additional showers and isolated thunder were developing ahead of upper shortwave trough over western Wisconsin. This activity was lifting NE into the central and northern part of the state. The surface trof should clear the area by 12Z with west to northwest flow expected in its wake. However, the upper level system will still be overhead with moderate forcing lingering over much of northeast Wisconsin through at least 18Z. Latest several runs of HRRR continue to indicate showers moving across the forecast area for much of the morning. Marginal stability and extensive cloud cover will limit tstorm threat, but certainly possible given strength of upper level system. In fact, HRRR hints at small window of opportunity for tstorm early afternoon before upper system departs. Behind the cold front, expect gusty NW winds and cool temperatures. High pressure moves in overnight and Sunday. Some patchy fog expected in the Wisconsin River Valley late tonight. Sunshine and comfortable weather expected Sunday. .LONG TERM...Sunday Night Through Friday Issued at 254 AM CDT Sat Sep 10 2016 Mostly dry weather with near normal temperatures expected during this part of the forecast with a ridge or zonal flow aloft. The exception will be during the first half of the upcoming work week when an upper trough and surface cold front make their way across Wisconsin. The chance for showers and some thunderstorms generally runs from Monday night through Tuesday. Highs on Monday, ahead of the system, will be well above normal. It should be cooler than normal on Wednesday in the wake of the cold front. After that, a warming trend starts in return flow on the back side of a departing surface high. Next weekend could be wet as another system approaches the area, but models had some issues so confidence in timing of the system is low. && .AVIATION...for 06Z TAF Issuance Issued at 906 PM CDT Fri Sep 9 2016 Scattered MVFR and even some IFR ceilings have developed during the evening. The low ceilings will become more widespread later tonight once the rain begins. Once in place, the IFR/MVFR conditions will linger into tomorrow. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....JKL LONG TERM......MG AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Lincoln IL
251 AM CDT SAT SEP 10 2016 .SHORT TERM...(Today and tonight) ISSUED AT 250 AM CDT Sat Sep 10 2016 Latest surface analysis indicates the cold front was over extreme eastern Iowa and should progress steadily east across our area this morning into early this afternoon. Just ahead of the cold front, a warm and very moist atmosphere was present with precipitable water values of 2.25 inches over southeast Illinois early this morning, so some of the rainfall pushing across parts of south-central through southeast Illinois will be heavy at times this morning. Most of the short term models were shifting the bulk of the shower activity off to our east by late this morning. However, with the rather deep 500 mb trof just to our west and decent low level cyclonic flow expected in the wake of the cold frontal passage later this morning, we still could see some lingering showers, especially east of the I-55 corridor in the 17z-20z time frame, so will hold on to some low chance POPs to cover for that possibility. Gusty northwest winds will filter in much cooler and less humid air with afternoon dew points lowering to the mid 50s west to the lower 60s far southeast with the high temperatures expected to range from 75 to 80 degrees. The front will be well off to our east tonight with surface high pressure building in from the west. The gusty west to northwest winds will diminish rather quickly this evening with some very comfortable overnight lows expected under a mostly clear sky. Lows will range from 50 to 55 degrees by Sunday morning. && .LONG TERM...(Sunday through Friday) ISSUED AT 250 AM CDT Sat Sep 10 2016 Evening model runs are in fairly good agreement on the overall synoptic situation next week, with a cutoff low developing over northern California Monday night and a separate upper trough passing just north of the northern Plains by midweek. The GFS is a bit faster with the surface boundary passing southward through the forecast area, but associated rainfall is generally out of our area by about midday Thursday. With an upper high over the southeast U.S., it may take until Wednesday to get any rain over the southeast CWA. By late in the week, model differences become more significant, with the ECMWF quicker in ejecting the cutoff low into the northern Plains. This results in a return of shower and thunderstorm chances as early as Thursday night, while the GFS favors more of an afternoon/evening Friday solution. Given that this is a fairly significant change from the previous ECMWF run, will favor more of the GFS solution and only go with slight chance PoP`s on Friday. Temperatures early in the week will creep up a bit as the upper flow becomes more southwesterly, but highs will dip again around midweek with the wave passing through the Great Lakes. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1152 PM CDT Fri Sep 9 2016 Precip is away from the TAF sites, but more is coming from the west and southwest for the overnight hours. So, have shra going at all sites in a few hours, and then VCSH for morning hours through around noon. Like the HiRes HRRR model with onset and ending of more precip this forecast. Where skies have sufficiently cleared/scattered out, dense fog and very low stratus have developed. So, LIFR or VLIFR conditions will prevail at PIA and BMI overnight and once precip moves in, then cig/vis should improve. MVFR cigs are then expected during the morning and afternoon as the frontal boundary finally moves into the area. Once precip moves east, fully, VFR conditions return; and expecting clear skies during the evening hours. Winds will be variable and then become west to northwest through remainder of the TAF period. Some gust possible to near 19kts during the afternoon after FROPA. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Auten
Area Forecast Discussion
National Weather Service Indianapolis IN
422 AM EDT SAT SEP 10 2016 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 322 AM EDT Sat Sep 10 2016 Thunderstorms will be possible until a cold front sweeps through the region late this afternoon. Cooler and much less humid air will arrive tonight with high pressure...with dry and comfortable conditions for Sunday into early next week. Scattered storms will return Tuesday night and Wednesday with a quick moving frontal boundary...followed by dry and seasonably cool weather for the remainder of the upcoming week. && .NEAR TERM /Today/... Issued at 322 AM EDT Sat Sep 10 2016 Convection has been slowly diminishing in coverage since 05Z as the low level jet prevalent over the region during the evening has moved away to the northeast. Lingering storms along a boundary near the I- 70 corridor have even become more isolated over the last hour or so as the airmass has stabilized. The airmass remained muggy early this morning with 07Z temps largely in the 70s. This will be the last day with a muggy feel to the air as a cold front is poised to sweep across the forecast area later this afternoon and usher in a much more refreshing airmass into the region. That cold front remains near the Mississippi River this morning with a broad area of convergence present over central Indiana. With lingering boundaries and deep moisture...will continue to see locally heavy downpours for the rest of the overnight. More widespread area of convection associated with a wave aloft over western Illinois back into Missouri will continue to expand east through the predawn hours and should arrive in the Wabash Valley by 10Z. Hi-res guidance led by the HRRR expand this area of convection across much of the forecast area during the morning focused especially near and north of the I-70 corridor. Will carry highest pops of the day during the morning to account. Heavy rainfall will be the primary concern with these storms as precip water values remain in excess of 2 inches. Should see precip coverage decrease by mid to late morning with a lull before renewed convective development occurs with the cold front during the afternoon. Expect this activity to be scattered with more organized linear convection developing along the front once it passes the forecast area and moves into a more unstable environment over Ohio by late afternoon. Will need to maintain chance pops this afternoon to account for scattered showers and storms...but should see the threat for rain ending from west to east after 19-20Z. Expect fairly rapid clearing behind the front with a strong surge of dry air and subsidence advecting into the region from the west. Likely to see gusts peak at 20-25mph this afternoon as well. Hang tight...the break from the muggy...tropical airmass will arrive prior to sunset this evening. Temps...low level thermals are generally supportive of a model blend with highs ranging from the upper 70s to lower 80s for most of the area. && .SHORT TERM /Tonight through Monday Night/... Issued at 322 AM EDT Sat Sep 10 2016 Forecast challenges are few through the period as high pressure bring tranquil weather to central Indiana. A large area of high pressure will be the dominant influence on weather across the Ohio Valley throughout the entire short term...with mainly clear skies expected for most of the period. May see diurnal cu on Sunday with lingering cold advection...but presence of a deep layer of dry air should mitigate cu development to some degree. Dewpoints will quickly fall back into the 50s tonight and remain there largely for the duration of the short term. Fantastic late summer/early fall weather for the region into early next week and well deserved after yet another stretch of exceptionally humid conditions. Enjoy. Temps...trended a bit closer to warmer MET guidance for highs both Sunday and Monday as abundant sunshine will support temps in the mid to upper 70s warming back to around 80 by Monday. Good setup for radiational cooling sets up for all three nights with some of our cool rural locales down near 50...especially Monday morning. && .LONG TERM /Tuesday through next Friday/... Issued at 223 AM EDT Sat Sep 10 2016 Ensembles in good agreement in bringing a short wave trough across the Great Lakes around the Tuesday night and Wednesday periods. Will keep some chance PoPs going in those periods to cover this system. Otherwise, it appears the upper pattern will amplify towards the end of next week, with deep troughing developing over the Plains, resulting in strong ridging over the eastern parts of the country. Ensembles suggest precipitation threat with this next trough will probably hold off until after this period, so will go mainly dry after Wednesday. && .AVIATION /Discussion for the 100900Z KIND TAF Update/... Issued at 422 AM EDT SAT Sep 10 2016 Convectively induced vorticity center near KSTL is expected to move through the local area later this morning. Wind profilers indicating about 30 kts of flow at 850mb, so there is still support for additional precipitation development with this feature. Expecting rain/embedded lightning strikes to affect the KIND terminal roughly 101000Z-101500Z. Brief IFR visibility restrictions in the heavier cells. Previous discussion follows. Mainly VFR Conditions are expected during the first few hours of the taf period. Some brief MVFR conditions will be possible during the max cooling hours of the morning. Thunderstorms over central Indiana should have exited the taf sites by issuance time...allowing just a VCSH mention for the first 90 minutes. Blow off from THunderstorms upstream will result in some VFR CIGS Overnight...however the warm and humid air mass along with this evenings rains and expected minimal dew point depressions...may result in some MVFR fog at the rural taf sites. Cold front is expected to sag across the taf sites on Saturday morning. Forecast soundings and Time heights show excellent saturation as the front passes. For now will use a VCSH mention...as instability appears limited. Although an isolated TSRA producing brief MVFR conditions cannot be ruled out at this point. However...mainly VFR conditions are expected with FROPA. Strong VFR conditions will return after 22Z Sat as the cold front sags to the southeast and High pressure builds across the area. Forecast soundings and Time height show excellent drying and subsidence. && .IND Watches/Warnings/Advisories...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....JAS AVIATION...JP/JAS
Area Forecast Discussion
National Weather Service Northern Indiana
424 AM EDT SAT SEP 10 2016 .SYNOPSIS... Issued at 415 AM EDT Sat Sep 10 2016 Showers and thunderstorms are likely across the region again today ahead of a cold front that will usher in cooler and drier air for the second half of the weekend. It will remain humid into early afternoon but once the cold front passes and winds become northwest...it will begin to feel less humid. Highs today will range from the middle 70s northwest to the lower 80s southeast. Low temperatures tonight will be in the 50s. && .SHORT TERM...(Today and Tonight) Issued at 419 AM EDT Sat Sep 10 2016 As we have discussed for the past several days...heavy rainfall and low end severe threat did indeed come to fruition thanks to tropical remnants from Newton and interaction with northern stream lead short wave. PWATs last evening in excess of 2 inches coupled with impressive mesolow/MCV and tropical airmass led to very efficient warm rain processes within low top supercell storms. Many areas received well over an inch of rainfall with some locations in excess of 3 to 4 inches. Attention now shifts to pcpn chances today as main northern stream trough approaches and pushes surface cold front through the area. Regional radar mosaic early this morning shows large area of rain with embedded tsra over MO and western IL expanding rapidly northeast ahead of synoptic system. HRRR experimental has a good handle on this precipitation and has verified quite well with short term pops over last few months. Have followed this models general trend for today. This suggests pcpn will reach western areas toward daybreak but begin to weaken/diminish as it moves east across the local area. Main cold front then follows early this afternoon with additional development of shra/tsra along it. The question will be how much we can destabilize behind initial pre-frontal showers and main front and where convection will begin to develop. Best chance for a strong or severe storm will be over mainly northwest Ohio where we could see some partial sun this afternoon and MLCAPES in the 1-2k j/kg range and 0-3km shear of 30-40kts. Considered a flood watch for today given overnight heavy rainfall but convection looks to be more scattered today so opted to hold off and allow day shift to monitor trends/development for more precise placement if needed. Once front clears the area late this afternoon should begin to see clearing with less humidity. A few models still trying to generate some light showers this evening post frontal with wrap around moisture but will only carry a slight chance pop early evening. && .LONG TERM...(Sunday through Friday) Issued at 419 AM EDT Sat Sep 10 2016 Broad area of high pressure to move in Sunday with much drier and cooler air. Dry weather expected through Monday night. Next chance for precipitation will be Tuesday and Tuesday night as fast moving short wave moves through the Great Lakes and associated cold front sags through the region. Kept pops in the low to mid chance range with best forcing north and limited moisture return as mid level ridge to our south blocks deeper moisture return. A refreshing Canadian airmass moves back in as high pressure slides through the Lakes. Highs in upper 60s to lower 70s and lows in the 40s look likely. Another system possible by Friday or Saturday with low chance pops for now. && .AVIATION...(For the 06Z TAFS through 06Z Saturday Night) Issued at 220 AM EDT Sat Sep 10 2016 The storms were still over Ft Wayne at the start of the TAF period. There should be a break in the storms until late morning into early afternoon ahead of the front. A lot of moisture and low clouds should persist early this morning with MVFR/IFR through the morning. More storms are expected with daytime heating as the front approaches basically from late morning through the afternoon. Otherwise, VFR conditions should persist behind the front. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement from 9 AM CDT this morning through Sunday morning for INZ003. MI...Beach Hazards Statement from 10 AM EDT this morning through Sunday morning for MIZ077. OH...NONE. LM...Small Craft Advisory from 10 AM this morning to 11 AM EDT Sunday for LMZ043-046. && $$ SYNOPSIS...Lashley SHORT TERM...Lashley LONG TERM...Lashley AVIATION...Skipper 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 Saint Louis MO
336 AM CDT SAT SEP 10 2016 .SHORT TERM... (Through Late This Afternoon) Issued at 336 AM CDT Sat Sep 10 2016 Cold front extending from northern IN southwest to just northwest of STL to just southeast of SGF will continue moving southeastward through the rest of the forecast area this morning as the upper level trough over the northern Plains moves eastward into the Great Lakes region. Large area of convection was moving through most of the forecast area early this morning producing high rainfall rates and periods of very heavy rainfall. Will continue the Flash Flood Watch across central MO into southwest IL including COU, JEF, FAM and the St Louis metro area until 12Z this morning. The latest HRRR model runs do show the stronger convective elements shifting east or southeast of our forecast area by 12Z Saturday with weaker scattered convection remaining this morning, then eventually shifting southeast of our area by afternoon. Despite a clearing sky later this morning and afternoon, high temperatures will be cooler than yesterday due to the low level cold air advection behind the cold front. Highs today will be about 5 to 10 degrees below normal. GKS .LONG TERM... (Tonight through Friday) Issued at 336 AM CDT Sat Sep 10 2016 (Tonight - Monday) This period will begin with northwest flow aloft and high pressure at the surface and transition by Monday to a W-SW flow aloft with southerly flow at the surface as the high pressure moves off to the east. This should equate to quiet wx, as temperatures start at below average values and recover to slightly above average by Monday. Nighttime min temps will reflect an early taste of autumn with anticipated readings in the upper 40s and lower 50s for most locations (higher in the STL metro heat island). Thanks to very little cloud cover during this period, daytime max temps will recover well Sunday and Monday, with temps near normal both days. (Tuesday - Friday) Rain chances return by late Monday night and continue into early Wednesday as a slow moving cold front drops thru. This represents the only wet period during this stretch with a surface high pressure building and dominating the region for late Wednesday thru Friday, with northeast to east surface flow, and should also return temps back to below average levels for mid to late next week. TES && .AVIATION... (For the 06z TAFs through 06z Saturday Night) Issued at 1100 PM CDT Fri Sep 9 2016 Thunderstorm complex will move through all TAF sites during the first 4 to 6 hours of this TAF period. Visibilities may briefly fall to IFR at times as the storms pass. Cold front will move through from 12 to 15Z as winds shift to the northwest and become gusty by midday Saturday. Ceilings may briefly fall into low end MVFR range behind the cold front but should quickly lift by late morning at all TAF sites. Skies will gradually clear during the afternoon. SPECIFICS FOR KSTL: Ongoing thunderstorms should end by around 10Z. Until then...visibilities could drop into the upper end IFR range in heavier rain. Cold front will move through by around 13Z with winds becoming northwest. Ceilings may briefly drop into the low end MVFR range but should lift to VFR by 15Z. Skies will gradually clear during the afternoon. Northwest winds could gust to near 18 mph. Browning && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Flash Flood Watch until 7 AM CDT this morning for Audrain MO- Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO- Gasconade MO-Jefferson MO-Lincoln MO-Moniteau MO-Montgomery MO-Osage MO-Saint Charles MO-Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-Warren MO- Washington MO. IL...Flash Flood Watch until 7 AM CDT this morning for Bond IL- Clinton IL-Madison IL-Monroe IL-Randolph IL-Saint Clair IL- Washington IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Mobile AL
331 AM CDT SAT SEP 10 2016 .NEAR TERM /Now Through Saturday night/...Upper air analysis this morning shows a vigorous mid-level trof pivoting eastward across the central and northern High Plains. The upper dynamics associated with this feature intersecting a surface frontal boundary draped from the upper Mid-West to the Red River Valley of TX/OK is bringing organized deep convection. The front makes steady southeast progress today into the Lower MS River Delta by this afternoon. The forecast area sees a narrow north to south mid-level ridge axis over the southeast between two upper level lows, one having moved into east TX and the other centered north of the Bahamas. For today as the front approaches the Lower MS River Delta, deep layer Gulf moisture is pulled northward, with precipitable water values improving to between 1.7 and 1.9 inches thru the day. Even so, the presence of the high level ridge remaining intact enough, acts to provide larger scale sinking motion. This offsets any weak lift that would develop as the airmass destabilizes. Will not totally discount a passing shower or storm, but potential of showers and storms will be kept minimal today with chances at or less than 10%, or very isolated in coverage. This is consistent with the latest high resolution HRRR and NAM-4KM solutions. Highs today range from 89 to 94. By tonight, the front mentioned earlier is forecast to enter the northwest zones this evening and begin to slow and eventually stall short of making it to the coast by daybreak Sun. Patchy late night fog possible with lows near 70 interior to the mid to upper 70`s beaches. /10 .SHORT TERM /Sunday Through Monday night/...A weak upper trof over the extreme northwest Gulf and Louisiana continues slowly eastward into the forecast area through Monday night, becoming more diffuse in the process. A weak frontal boundary will be located over the forecast area on Sunday which dissipates Sunday night followed by a surface ridge building over the extreme southeast states on Monday. The surface ridge is weakened over the forecast area on Monday however, due to a surface reflection associated with the weak upper trof. The frontal boundary is expected to located over the interior portion of the forecast area on Sunday and have gone with chance pops for most of the area except for slight chance pops closer to the coast. Identifying the portion with the best convective potential is more difficult on Monday given the weak surface reflection from the weak upper trof, and with a favorable convective environment have gone with chance pops for now for essentially the entire area. Highs will mostly be in the lower 90s with upper 80s near the coast, although some inland locations may see the mid 90s on Sunday. Lows will be in the lower 70s except for mid 70s near the coast. /29 .LONG TERM /Tuesday Through Friday/...The weak and diffuse upper trof over the forecast area finally dissipates on Wednesday with upper ridging building into the region and eastern states through Thursday. There continue to be indications of a poorly defined surface reflection over the area on Tuesday, and have continued with chance pops for the area. Another weak frontal boundary may move into the area Wednesday into Thursday and linger through Friday and have gone with slight chance to chance pops. Highs will be in the lower 90s through Thursday with upper 80s near the coast, then somewhat cooler highs follow for Friday ranging from near 90 inland to the mid 80s at the coast. Lows will be in the lower 70s except for mid 70s near the coast. /29 && .MARINE...Weak surface high pressure holds into the southeast thru the weekend. A weak frontal boundary sinks southward across the Lower Mississippi River Delta today. The frontal boundary looks to stall just short of the coast by Sun and remain nearly stationary into the beginning of next week. Winds mostly light and becoming onshore today and Sun with little change in seas, 2 feet or less. For Mon thru Wed, high pressure sets up along the east coast and southeast US resulting in an easterly fetch. Isolated to scattered showers and storms. /10 && .PRELIMINARY POINT TEMPS/POPS... Mobile 91 73 91 73 / 10 10 20 20 Pensacola 89 75 89 75 / 10 10 20 20 Destin 90 78 89 77 / 10 10 20 20 Evergreen 92 70 94 71 / 10 10 30 20 Waynesboro 94 70 91 70 / 10 10 50 20 Camden 93 69 93 71 / 10 10 30 20 Crestview 93 71 93 71 / 10 10 20 20 && .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 Marquette MI
419 AM EDT SAT SEP 10 2016 .SHORT TERM...(Today and tonight) Issued at 418 AM EDT SAT SEP 10 2016 00Z raobs/latest wv imagery and RAP analysis shows a deepening upr trof over the Ncentral Conus with a fairly strong shrtwv lifting out of the base of this trof into the Upr MS river valley. Since the forcing associated with this feature has not yet interacted with an axis of hier pwat /up to 1.5 inches per SPC analysis/ and weak sfc- h85 troffing stretching fm Scentral WI into Ern Upr MI, numerous showers are present over the far SE cwa along the axis of hier mstr. Sct-numerous showers are present over wrn Upr MI into MN ahead of cold fnt associated with the shrtwv. Temps are fairly warm early this mrng with 00Z h85 temps 16C at GRB/APX. H85 temps within the thermal trof over the nrn plains behind the cold fnt are as lo as 6- 8C. There are numerous fcst concerns in the short term, including pops and then winds associated with a sfc lo pres that is fcst to dvlp and intensify on the trof axis just to the SE ahead of the incoming shrtwv. Early this mrng/today...As shrtwv to the SW lifts into the Upr Lks, vigorous dpva/deep lyr qvector cnvgc and upr dvgc ahead of this disturance and in RRQ of 120kt h3 jet max near James Bay should be sufficient to result in a rapid expansion of the showers, espcially over the E half of the cwa closer to the sfc-h85 trof and hier pwat. The GFS has been fairly consistent showing an axis of strengthening h85-7 fgen/uvv over this part of the cwa on the wrn flank of the trof axis this mrng. So wl fcst the hiest categorical pops/pcpn amnts/with embedded TS in the presence of SSI down to about -1C in this area. Fortunately, this band of sharper forcing is fcst to lift fairly quickly to the NE and into SE Ontario toward 15Z. But lighter rains wl persist until the deep lyr qvector cnvgc/hier h85-5 RH lift out to the NE as well after 18Z. With the arrival of deep lyr qvector dvgc/subsidence/mid lvl drying during the aftn, there should at least be partial clrg over the W half of Upr MI. Models continue to show sfc cyclogenesis as well on the trof axis with more rapid dvlpment occurring once the sfc lo exits to the E. The 00Z NAM is strongest with the NNW winds that are fcst to dvlp on the wrn flank of this departing sfc lo pres, with h925 winds fcst up to 35 to 40 kts in areas E of Munising/Grand Marais. With an influx of the cooler air to the NW over the relatively warm waters of Lk Sup, the setup seems favorable for very gusty winds at least close to advy criteria. But most of the other models are weaker with the fcst wind speeds, so wl hold off on any headlines for now and continue going special wx statement for Alger/Luce counties for gusty winds to arnd 40 mph and some beach erosion accompanying the bldg waves/above normal Lk Sup water lvls. These hi waves wl contribute to a hi swim risk along the Lk Sup waters fm Marquette County to the E. Tngt...The strong NNW winds over mainly the Ern cwa wl diminish this evng as the lo the E exits into Quebec and sfc hi pres blds toward the area under quickly rising h5 hgts ahead of an aprchg shrtwv rdg. The incoming airmass, with h85 temps down to 5C, wl probably be sufficiently cool to maintain some lk clds over the Keweenaw and the E, but fcst sdngs sug the near sfc lyr wl be too dry for any pcpn. Influx of cooler air wl drop min temps into the 40s away fm moderation off Lk Sup. .LONG TERM...(Sunday through Friday) Issued at 257 AM EDT SAT SEP 10 2016 Prior to a cold front moving through, Sun and at least most of Mon look pleasant with mostly clear skies, highs in the 70s and lows in the 50s. That front will bring chances for precip Late Mon into early Tue depending on shortwave energy and moisture availability. Behind the front, a shortwave trough may move through on Tue, combining with NNW winds and 850mb temp AOB 7C to bring isolated-scattered showers. Highs on Tue will be in the upper 50s to mid 60s, warmest SE. 850mb temps could fall to near 0C Tue night as a SFC high moves in. The cold temps will initially lead to lake effect clouds and isolated showers, but those should be diminishing as the dry high moves in. Certainly potential for a hard freeze over the interior W, but for now have lows down to 32F. Airmass temps look to rebound to 10-12C late in the week. There is potential for precip Fri-Sat, but confidence is very low. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 122 AM EDT SAT SEP 10 2016 Rain will continue over the three TAF sites early this morning with the main impacts occuring at KSAW where there will be the possibility of IFR ceilings and visibilities for a brief period between 9Z and 12Z. KIWD and KCMX will see MVFR ceilings through the night into the early daylight hours before northerly winds pick up and conditions improve. Wind gusts up to 25 knots are possible this morning but then the winds will relax while the precipitation ends from west to east this afternoon. VFR conditions prevail into the evening hours with winds diminishing to less than 10 knots by 0z at KSAW and KIWD, and shortly thereafter at KCMX. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 418 AM EDT SAT SEP 10 2016 A cold front is moving across Lake Superior early this morning, with winds shifting to the NNW in its wake. As a lo pres moves thru eastern Upper MI this morning and deepens over SE Ontario today, expect the NNW winds to increase up to 30 kts over much of the E half of the lake. Since widespread gales do not appear likely, opted to drop the previous gale watch. But there could still be some gale force gusts over the eastern portion of the lake this afternoon into the evening before the lo pres moves farther away and an approaching hi pres ridge cause the winds to diminish tonight into Sun. As the hi pres shifts to the E and a tighter pres gradient develops again on Sun night into Mon ahead of an approaching cold front, expect SSW winds to increase up to 30 kts. Winds will shift back to the NNW late Mon into Tue following the cold frontal passage, but these winds are not expected to be higher than 20 kts. Winds will diminish and back to the W as trailing hi pres moves thru the Western Lakes on Wed. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...KC LONG TERM...Titus AVIATION...RJT MARINE...KC
Area Forecast Discussion
National Weather Service Paducah KY
321 AM CDT SAT SEP 10 2016 .SHORT TERM...(Today through Monday) Issued at 321 AM CDT Sat Sep 10 2016 The consensus of HRRR runs over the last few hours take the area of convection over the St Louis metro area northeastward, which may bring a stray shower or storm into the northwest corner of Perry or Jefferson county through sunrise. Farther southwest, they indicate continued weakening of the former convective band over southwest Missouri as it approaches our western counties by sunrise. There may not be much of this left at all, but will have a band of 20-30% PoPs moving eastward across the entire area through 16Z or so, associated with the outflow boundary. There could be some increase in convective development along this boundary over west Kentucky mid to late morning. The cold front will be approaching the Ohio and Wabash Rivers by midday, and this is when convection should begin to develop near it. The primary window east of the rivers will be 18Z-20Z. Figure that it will eventually result in a fairly solid line over the Pennyrile, but it may be more scattered initially. Cannot argue with SPC`s Marginal Risk of severe weather along and east of a line from Murray to Owensboro. Surface-based instability should be somewhere in the vicinity of 2000J/kg, but wind fields will not be that strong. There will be some deeper layer shear, albeit unidirectional, but not much low-level shear. Look for some damaging wind potential with the line or line segments in the early to mid afternoon. The storms should be moving along quickly enough to limit the impact of locally heavy rainfall. All indications are that this activity will be east of the area by 22Z, but kept some smallish PoPs in the southeast corner of the region til sunset. After this convection exits the area, it will be much cooler and drier for the remainder of the short term period through Monday. Stayed close to the consensus of all available guidance for highs today and lows tonight and Sunday night. Favored the slightly warmer consensus MOS numbers for highs Sunday and Monday, due to the sunny and dry conditions expected. .LONG TERM...(Monday Night through Saturday) Issued at 321 AM CDT Sat Sep 10 2016 There is fairly high forecast confidence in the extended periods of this forecast. The medium range models continue to trend drier for much of the work week with high pressure at the surface and aloft continuing to influence the region. Surface high pressure will keep the low-level wind fields muddled heading into Wednesday, as a cold front approaches the area. This effectively causes the cold front to dissipate, leaving just a re-inforcing surge of high pressure to sweep through the area Wednesday. We may see some scattered convection reach the far northwest portions of the forecast area late Tuesday night, but all indications are that any convection will dissipate over our northern territories Wednesday morning. Will continue with only 20-30% PoPs for this potential. The forecast then is dry through Thursday night. The 00Z ECMWF and GFS bring a good portion of a former closed low over the Inter-mountain west northeast into the Upper Midwest Friday into Saturday. This could eventually bring a decent chance of convection into our region Friday, and most likely on Saturday. This will be determined by how quickly the east coast upper high gets suppressed to the southeast Atlantic coast. Will have slight chances on Friday increasing to decent chances on Saturday. Temperatures should be at or above normal Tuesday and Wednesday, but will drop just a shade below normal for Thursday and possibly Friday. Saturday could see warmer temperatures, but only if the convection holds off. && .AVIATION... Issued at 1146 PM CDT Fri Sep 9 2016 Convection in near term will affect areas from just near KMDH to KEVV and KOWB. After a lull, chances pick up again tomorrow with the main front and upper trof. Mainly VFR conditions. But MVFR cigs and IFR vsbys possible with convection at the terminals. Winds will eventually become W then NNW (6-12 kts) behind the front on Saturday, with skies clearing late day, and on into the evening. && .PAH Watches/Warnings/Advisories... IL...None. MO...None. IN...None. KY...None. && $$ SHORT TERM...DRS LONG TERM...DRS
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
425 AM EDT SAT SEP 10 2016 .SYNOPSIS... 08Z water vapor and H4 RAP analysis shows the Florida Peninsula in between a ridge of upper level high pressure over the central Gulf of Mexico...and an upper low spinning to the east of the region. The flow around these features is providing a deep layer mid/upper level northerly flow that was sampled well in the 00Z KTBW RAOB. Well removed from our region we find a rather significant amplification to the northern stream digging through the upper midwest. This amplification will bring a cooler airmass to the Great Lakes/High plains this weekend...but will not be making enough southward progress to break the stubborn summer pattern over our region. These amplifications will become more frequent as we head deeper into September and then October...and eventually our first cold front of the season will arrive. But not yet... In the lower levels...high pressure resides just to the north of the region providing a synoptic easterly flow across the FL peninsula. Of interest...is a weak...but well-defined area of low migrating westward into the southeast Gulf of Mexico. This little low may look scary from a radar perspective...but atmospheric conditions are not favorable for significant development...and the low itself will be moving steadily away from our area through the weekend. && .SHORT TERM (TODAY THROUGH SUNDAY)... The forecast for the weekend is not that dissimilar to what we have experienced the past couple of days...as the synoptic pattern does not change much. Both Saturday and Sunday will feature dry conditions during the morning and early afternoon hours...with light easterly winds and temperatures climbing to within a degree or two either side of 90. Widely scattered to scattered shower and storms will be developing within the easterly flow after mid-afternoon and migrating westward toward the I-75 corridor. As has been the case the past several days...the best chances for a late day shower or storm will exist to the south of the I-4 corridor. The differences north to south are subtle...but just enough mid-level residual dry air still exists to the north of Tampa to help keep the overall convection suppressed. Overall...no big surprises are anticipated in terms of sensible weather. The potential for afternoon/evening storms will then be increasing region-wide after the weekend. && .MID/LONG TERM (MONDAY THROUGH NEXT FRIDAY)... Surface high pressure will be positioned north of the peninsula through the period keeping us in a easterly wind flow pattern. Deep moisture will be in place for much of the extended with PWs near 2 inches. This deep moisture will allow for daily scattered to numerous showers and thunderstorms moving towards the Gulf Coast during the mid to late afternoon hours. Temperatures will also remain seasonable, with highs in the upper 80s to lower 90s. && .AVIATION (06Z TAFs)... VFR conditions prevail in these early morning hours. Some potential for a few small areas of MVFR cigs along the I-4 corridor terminals between 09-13Z. Potential is low enough to leave out of current TAFs...but will be monitoring conditions. General VFR conditions prevail through Saturday. Widely sct storms develop and move westward toward the coast after 19Z. Have included VCTS during the late afternoon/early evening for this potential. Any storms dissipate before 03Z Sunday. && .MARINE... High pressure will remain centered just north of the region through the weekend. This ridge of high pressure will dominate the weather for the next several days. A weak area of low pressure moving through the southeast Gulf of Mexico will continue to migrate westward today...but is not expected to have much...if any impacts on our local weather. && .FIRE WEATHER... High pressure will hold in place just to the north of the region through the weekend...keeping a light easterly flow in place across the Florida peninsula. Low level moisture will keep relative humidity values well above critical levels...and no significant fire weather concerns are anticipated. Fog Potential...Patchy fog is possible in sheltered locations toward dawn the next several mornings...however no dense fog or significant visibility concerns are expected. && .Preliminary Point Temps/PoPs... TPA 91 77 90 76 / 40 30 40 30 FMY 91 75 90 76 / 50 40 50 30 GIF 92 74 91 75 / 30 10 30 10 SRQ 90 76 89 76 / 40 40 40 30 BKV 92 72 91 74 / 40 20 20 30 SPG 91 78 89 78 / 40 30 40 30 && .TBW Watches/Warnings/Advisories... FL...None. Gulf waters...None. && $$ SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WEATHER...Mroczka LONG TERM/DECISION SUPPORT...McKaughan
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
741 AM MDT SAT SEP 10 2016 .UPDATE... Updated to increase coverage of thunderstorms across east central and southeast areas, mainly during the morning, in accordance with recent satellite and radar trends. Left a slight chance in during the early afternoon across eastern Chaves and southern Roosevelt Counties in accordance with the HRRR and RAP13 mesoscale models. 44 && .PREV DISCUSSION...547 AM MDT SAT SEP 10 2016... .AVIATION... 12Z TAF CYCLE Main impacts thru this morning include widespread low cigs near 050 across eastern NM and strong winds at KABQ. Aviation weather warning continues for the Sunport through late morning before winds taper off early this afternoon. A few -shra/tsra over the far eastern plains near KCVN/KCVS will move southeast into TX thru 15Z. Cigs near 050 will slowly erode today while winds shift from northeast to east then southeast. Focus for a few -shra/tsra with gusty outflows will shift to the Cont Dvd aft 22Z. This activity is expected to move east toward the RGV while dissipating aft sunset. Guyer && .PREV DISCUSSION...335 AM MDT SAT SEP 10 2016... .SYNOPSIS... A back door cold front will continue to bring strong winds below canyons opening into the Rio Grande Valley from the east until mid morning. In the wake of the front, high temperatures will be 10 to 25 degrees cooler than yesterday`s readings central and east, and around 4 to 9 degrees cooler in the west. A few showers and storms will be possible today across the southern mountains and southeast plains. Sunday through the middle of the coming week will bring better precipitation chances as an upper level trough of low pressure deepens over the western U.S., drawing moisture northward over New Mexico and another back door cold front into the state. The upper trough will then form a low pressure system that should eject northeastward from the Great Basin across the northern Rockies during the latter half of the work week. This will filter drier air into western New Mexico, but central and eastern areas should continue to have daily rounds of showers and storms as moisture lingers there. High temperatures will rebound Sunday only to trend cooler with the increasing moisture during the first half of the coming week. && .DISCUSSION... Models are now in better agreement on the aforementioned upper trough forming a closed low over the Great Basin on Monday night. The system will draw a moist back door cold front into the state from the NE Monday night and Tuesday with another gusty east canyon wind possible in the Rio Grande Valley late Tuesday into the night. A wetter period is expected east of the continental divide Monday night through Wednesday night, especially from the central mountain chain eastward do to favorable dynamics provided by the upper low and the enhanced low level moisture. The base of the upper trough should cross Thursday or so, decreasing precip chances as drier air makes better inroads from the west. However, GFS and ECMWF agree on yet another back door cold front Thursday night that will increase moisture and precipitation chances along and east of the central mountain chain again through the end of the week. The east wind may push some of this moisture as far west as the continental divide. 44 && .FIRE WEATHER... Strong winds below canyons in the RGV and across the eastern plains will taper off after sunrise. Much cooler air behind a back door cold front will trend temps 15 to 20F below Friday. Min humidities will trend 15 to 20% higher than Friday with the infusion of cooler air. Vent rates today will deteriorate to poor/fair most areas in the wake of the cold front. Drier air will start working into the region from east to west tonight and allow for cooler overnight lows as well. An upper high will build overhead Sunday then break down Monday. High temps will warm closer to normal all areas. Low level moisture will begin to seep northward along the Cont Dvd Sunday and generate some late day storms that may drift into the RGV during the evening hours. Moisture will increase even more Monday as deep southerly flow shifts north along the western edge of the upper high. Better coverage of storms with larger wetting footprints is expected for at least the central portion of NM. Another back door front will enter eastern NM Tuesday and kick off widespread coverage of storms through Wednesday as far west as the Cont Dvd. Temps will trend much cooler again most areas with very good to excellent overnight humidity recoveries. Vent rates will deteriorate once again to poor/fair just about everywhere. Models are no longer in good agreement with the upper pattern and how far and long the moisture stays put over NM. At a minimum there will at least be daily recycling of moisture in the form of showers/storms near the central mt chain. 43 && .ABQ WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 10 AM MDT this morning for the following zones... NMZ520-525. High Wind Warning until 10 AM MDT this morning for the following zones... NMZ519. && $$ 44
Area Forecast Discussion
National Weather Service Bismarck ND
914 AM CDT Sat Sep 10 2016 .UPDATE... Issued at 914 AM CDT Sat Sep 10 2016 Inherited forecast on track. Had a few pixels of -tsra across the north in the grids, these were cleaned up as should be dry with zero chance for thunder today. Patchy fog was removed for this morning for the update. UPDATE Issued at 636 AM CDT Sat Sep 10 2016 Main adjustment was to blend to latest hourly temps which were running colder than forecast. Tioga is currently the coldest spot with a temp at 11Z of 36 degrees, with most other locations in the low to mid 40s. Will also maintain patchy fog for the northwest and north-central, although have only seen a couple obs from Tioga reporting lower visibility. && .SHORT TERM...(Today and tonight) Issued at 410 AM CDT Sat Sep 10 2016 Correction issued for wording of possible frost on Tuesday morning in long term discussion. Included patchy fog for early this morning mainly northwest and northcentral, similar to HRRR and RAP solutions which indicate fog potential. So far, no reports of fog or indications on satellite fog product, but temp/dew point spreads are very low with clear skies and light winds. Otherwise, shortwave trough that supported showers and isolated thunderstorms into Friday evening will progress to the Great Lakes region today with upper level ridging building in over the Northern Plains today. This will result in a dry and mild day with highs in the upper 60s to low 70s. Will also see skies initially clear give way to increasing clouds during the day, especially north. On Saturday night and Sunday, upper level flow becomes more zonal then eventually southwesterly as long wave trough upstream begins to drop into the northwest CONUS. .LONG TERM...(Sunday through Friday) Issued at 410 AM CDT Sat Sep 10 2016 Low level southwest flow will result in warm temps on Sunday with highs in the 70s north to low/mid 80s south-central. A strong cold front will move into northwest ND by early afternoon Sunday, reaching the southeast part of the state by early evening. Models indicate a chance of some light showers. High temps on Monday will be 20 degrees cooler than Sunday with brisk northwest winds behind the front. Surface high pressure center drifts to western ND by 12z Tuesday, which will support the possibility of frost Tuesday morning. Upper level ridging again moves in until midweek, when closed upper low over Intermountain West begins to lift toward the Northern Plains with showers and thunderstorms possible beginning Thursday. Some timing differences exist between GFS and ECMWF, though overall agreement with the upper low drifting across ND late in the week. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 914 AM CDT Sat Sep 10 2016 VFR conditions expected throughout the period. Will see increasing mid to upper level clouds from west to east today with little impacts to aviation. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NH SHORT TERM...JNS LONG TERM...JNS AVIATION...NH
Area Forecast Discussion
National Weather Service State College PA
759 AM EDT SAT SEP 10 2016 .SYNOPSIS... Low pressure will track northward through the Great Lakes today, pushing a trailing cold front through central Pa tonight. High pressure will build into Pennsylvania Sunday and remain over the state through early next week. A cold front will push south across the region Wednesday, followed by another high pressure system late in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Radar loop at 09Z showing a few lingering showers across northern Pa assoc with retreating warm front. Convection-allowing ensembles and latest HRRR support the chance of showers across the northern tier until arnd 12Z-14Z. IR imagery at 09Z already showing clearing skies across southern Pa and expect that trend to expand north later this morning, as the region breaks into the warm sector ahead of low pressure ovr the Grt Lks. Model soundings support a partly sunny and hot Saturday with readings by afternoon well into the 80s for most of the area and the low 90s in the Susq Valley. The combination of heat and dwpts near 70F should push apparent temps into the mid to upper 90s across the southeast counties. Potent mid lvl shortwave and assoc cold front will approach the region late today, bringing an increasing chance of showers/storms toward evening across the NW Mtns. Further east, scattered diurnally-driven, pulse-type convection is likely to develop across the eastern counties. Both the NCAR ensemble and SPC SSEO support this idea of sct afternoon shra/tsra across the central Mtns and Susq Valley. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Focus this evening will be on the potential of svr weather across the northwest counties with arrival of cold front. Convection- allowing models indicate a broken line of tsra will move into the NW Mtns around 00Z supported by strong, deep layer shear and modest instability. Expect a diminishing svr wx threat further east, with fropa occurring late at night across the central mtns and Susq Valley. SPC slight risk covers 6 of our northwest counties this evening. Cold front and assoc dwindling line of convection should be exiting the Lower Susq Valley by dawn Sunday. Arrival of high pressure and low PWAT air mass will bring clearing skies and much lower humidity Sunday with max temps close to seasonal levels. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Broad agreement among med range models for a period of fair weather early next week, as sfc high builds eastward across Pa. Although the accompanying air mass will be much drier, mdl 8h temps still indicate above normal temps, esp as southerly flow strengthens Tuesday ahead of next cold front. Scattered showers in the fcst for Wednesday with passage of cold front, then another stretch of fair weather/low humidity appears likely late in the week, as NAEFS/ECENS show high pressure building into the northeast states. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... A warm front near the NY/PA border will lift northward this morning. Low pressure will track northward through the Great Lakes today, pushing a trailing cold front through central Pa tonight. IFR/MVFR restrictions that have developed in many areas overnight will hang tough through 14-16z (maybe even as late as 18z in a few spots) before improving to VFR. Light winds through midday will pick up from the SW to around 8-12mph with gusts to 14-22mph this afternoon. Isolated tstms may develop late this afternoon in hot/humid airmass with local impacts. As a cold front moves in from the west this evening, expect a potentially strong line of showers/tstms to impact the NW mtns around 00z. This line should weaken as it tracks eastward, but storms could be accompanied by locally gusty winds along its path through 06z. Cig restrictions expected behind the front tonight over the western mtns. Outlook... Sun...AM log cigs possible w mtns. Mon-Tue...No sig wx. Wed...Chc shra/tsra. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ Synopsis...Fitzgerald Near Term...Fitzgerald Short Term...Fitzgerald Long Term...Fitzgerald/Gartner Aviation...RXR
Area Forecast Discussion
National Weather Service Des Moines IA
633 AM CDT Sat Sep 10 2016 .SHORT TERM.../Today/ Issued at 309 AM CDT Sat Sep 10 2016 Overall quiet and enjoyable day expected over the region today. First in a series of cold fronts already exiting the southeast at 05z with a secondary cool front/wind shift over southern Minnesota. The second boundary has not yet realized the cooler air aloft but is a reflection of an upper level H850 cool front located from near International Falls southwest to near Huron at 00z. This front is tracking into northern Iowa at 06z and has resulted in another period of light showers and lower stratus. The feature will pull quickly east southeast overnight and will be out of the area prior to dawn. In the wake of the second boundary a reinforcing cooler and drier airmass over the Northern Plains will move southeast into Iowa today through tonight. Despite the drier airmass today there should be some fair weather clouds this afternoon. Any time a modest to significant rainfall occurs the evaporation of surface moisture normally is enough to create fair weather clouds the day following the rain...unless subsidence is extraordinarily large. Today...Bufr soundings show few to scattered shallow cumulus at about 4000 feet this afternoon setting up shop between about 11 am and 2 pm this afternoon. As well...mixing will begin to occur between 14 and 16z with gusts nearing 30 mph at times during the afternoon hours. Highs will be very comfortable and even cooler than our normal highs in the mid 70s north to upper 70s south. Today we will end up about 5 to 7 degrees cooler across the board. .LONG TERM.../Tonight through Friday/ Issued at 309 AM CDT Sat Sep 10 2016 Saturday night through Sunday night... Weather: Quiet, near normal temperatures Impact: None Confidence: High To round out this weekend, high pressure will propagate across the Ozarks Saturday night and push into the Ohio Valley region by Sunday afternoon. This will place Iowa in S/SW flow, helping to increase Sunday afternoon temps a few degrees vs Saturday`s max temps. With a dry fcst sounding profile, clouds will be hard to come by. Monday and Tuesday... Weather: Shower and thunderstorm potential Impact: Heavy rainfall Confidence: Medium As the aforementioned high pushes further east, an upper trough will swing eastward across Canada Monday into Tuesday. Models in good agreement depicting an impulse ejecting off the upper low and shooting through the upper Midwest, making it into MN by Monday afternoon. This sfc low will have an attendant cold front which will be highlighted by a notable dewpoint depression tailing it. Sfc dewpoints will go from the mid/upper 60s ahead of the boundary, to the mid/upper 40s behind the boundary. A 30 to 35kt LLJ will aid in rushing low level gulf moisture to Iowa by Monday afternoon. Q- vectors pointing towards warm air and crossing potential temp gradient as boundary passes through NW Iowa during daylight hours, indicating frontogenesis. Thus, may have to further increase PoP and QPF across northern CWA in future updates. In terms of impacts, overall setup not cause for alarm at this point. 00z Sat models trending upwards with PWATs, bringing to Iowa values of around 1.75", which is approx +1 std dev. 0-6 km muCAPE values approach 1500 j/kg. Warm cloud depths indicated to be near 1300m coincident with the Monday PM moisture surge. Big negative for severe wx is strong 750mb cap shown in fcst soundings. It appears timing will be difficult to get boundary and moisture surge to line up during peak daytime heating hours. Wednesday through Thursday... Weather: Below normal temperatures Impact: None Confidence: Medium A stacked 1030mb high will follow this system and advect much cooler air to the region. 850mb temps will be in the +7C to +11C range into Thursday. Models trying to push the 1030mb high into the Great Lakes Region by Thursday morning, but this seems awfully fast given the magnitude of this high. Therefore, have lowered Thursday temps vs guidance and have begun to push Friday`s PoP arrival back...with slight expectation for them to be scaled back in subsequent updates. && .AVIATION.../For the 12Z TAFS through 12Z Sunday morning/ Issued at 633 AM CDT Sat Sep 10 2016 Main challenge today will be wind and patch of IFR stratus developing across north central Iowa at this time. HIRES HRRR has areal coverage of IFR stratus expanding south to Des Moines this morning all behind a boundary bringing colder air over the region. HRRR looks a bit overdone. Expect stratus to mix out by 15z with only KMCW and perhaps KALO affected. Have scattered out KALO to 015 by 15z. Remainder of day...breezy northwest flow of 15-25kts will diminish by 23z with light southwest winds aft 00z to end of period with VFR conditions. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...REV LONG TERM...Kotenberg AVIATION...REV
Area Forecast Discussion
National Weather Service Green Bay WI
626 AM CDT SAT SEP 10 2016 Updated aviation portion for 12Z TAF issuance .SHORT TERM...Today...Tonight...and Sunday Issued at 254 AM CDT Sat Sep 10 2016 07Z surface analysis indicates low pressure over east-central Wisconsin, just northeast of Oshkosh, accompanied by N-S trof/cold front. Line of showers forming along trough and moving NE while additional showers and isolated thunder were developing ahead of upper shortwave trough over western Wisconsin. This activity was lifting NE into the central and northern part of the state. The surface trof should clear the area by 12Z with west to northwest flow expected in its wake. However, the upper level system will still be overhead with moderate forcing lingering over much of northeast Wisconsin through at least 18Z. Latest several runs of HRRR continue to indicate showers moving across the forecast area for much of the morning. Marginal stability and extensive cloud cover will limit tstorm threat, but certainly possible given strength of upper level system. In fact, HRRR hints at small window of opportunity for tstorm early afternoon before upper system departs. Behind the cold front, expect gusty NW winds and cool temperatures. High pressure moves in overnight and Sunday. Some patchy fog expected in the Wisconsin River Valley late tonight. Sunshine and comfortable weather expected Sunday. .LONG TERM...Sunday Night Through Friday Issued at 254 AM CDT Sat Sep 10 2016 Mostly dry weather with near normal temperatures expected during this part of the forecast with a ridge or zonal flow aloft. The exception will be during the first half of the upcoming work week when an upper trough and surface cold front make their way across Wisconsin. The chance for showers and some thunderstorms generally runs from Monday night through Tuesday. Highs on Monday, ahead of the system, will be well above normal. It should be cooler than normal on Wednesday in the wake of the cold front. After that, a warming trend starts in return flow on the back side of a departing surface high. Next weekend could be wet as another system approaches the area, but models had some issues so confidence in timing of the system is low. && .AVIATION...for 12Z TAF Issuance Issued at 621 AM CDT Sat Sep 10 2016 Scattered MVFR and IFR ceilings continue across airports this morning. Rain showers have become more widespread as upper level storm system moves across state. Conditions will improve from west to east beginning 15Z, however gusty NW winds near 20-25 knots are expected into the afternoon. Patchy fog with vsby less than 2 miles in Wisconsin River Valley locations and other low- lying areas. Clear skies will become partly cloudy with some cumulus expected Sunday. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....JKL LONG TERM......MG AVIATION.......JKL
Area Forecast Discussion
National Weather Service Indianapolis IN
1026 AM EDT SAT SEP 10 2016 .UPDATE... The AVIATION section has been updated below. && .SYNOPSIS... Issued at 322 AM EDT Sat Sep 10 2016 Thunderstorms will be possible until a cold front sweeps through the region late this afternoon. Cooler and much less humid air will arrive tonight with high pressure...with dry and comfortable conditions for Sunday into early next week. Scattered storms will return Tuesday night and Wednesday with a quick moving frontal boundary...followed by dry and seasonably cool weather for the remainder of the upcoming week. && .NEAR TERM /Rest of Today/... Issued at 1015 AM EDT Sat Sep 10 2016 UPDATE...Most of the showers and thunderstorms were now located north of a Frankfort to Muncie line and these will continue to move rapidly to the northeast. Could see a lull next few hours with more development along the cold front which will push into western sections near or shortly after noon and then push east across the rest of our region by 21Z. Expect the best chances of storms to reach western sections towards 17Z...central sections 18Z to 19Z and eastern areas 20-21Z. Everything will dry out quickly once front moves through. Could be some wind gusts in excess of 25 mph with cold front. Otherwise current forecast is on track. Portion of previous near term discussion follows... This will be the last day with a muggy feel to the air as a cold front is poised to sweep across the forecast area later this afternoon and usher in a much more refreshing airmass into the region. That cold front remains near the Mississippi River this morning with a broad area of convergence present over central Indiana. With lingering boundaries and deep moisture...will continue to see locally heavy downpours for the rest of the overnight. More widespread area of convection associated with a wave aloft over western Illinois back into Missouri will continue to expand east through the predawn hours and should arrive in the Wabash Valley by 10Z. Hi-res guidance led by the HRRR expand this area of convection across much of the forecast area during the morning focused especially near and north of the I-70 corridor. Will carry highest pops of the day during the morning to account. Heavy rainfall will be the primary concern with these storms as precip water values remain in excess of 2 inches. Should see precip coverage decrease by mid to late morning with a lull before renewed convective development occurs with the cold front during the afternoon. Expect this activity to be scattered with more organized linear convection developing along the front once it passes the forecast area and moves into a more unstable environment over Ohio by late afternoon. Will need to maintain chance pops this afternoon to account for scattered showers and storms...but should see the threat for rain ending from west to east after 19-20Z. Expect fairly rapid clearing behind the front with a strong surge of dry air and subsidence advecting into the region from the west. Likely to see gusts peak at 20-25mph this afternoon as well. Hang tight...the break from the muggy...tropical airmass will arrive prior to sunset this evening. Temps...low level thermals are generally supportive of a model blend with highs ranging from the upper 70s to lower 80s for most of the area. && .SHORT TERM /Tonight through Monday Night/... Issued at 322 AM EDT Sat Sep 10 2016 Forecast challenges are few through the period as high pressure bring tranquil weather to central Indiana. A large area of high pressure will be the dominant influence on weather across the Ohio Valley throughout the entire short term...with mainly clear skies expected for most of the period. May see diurnal cu on Sunday with lingering cold advection...but presence of a deep layer of dry air should mitigate cu development to some degree. Dewpoints will quickly fall back into the 50s tonight and remain there largely for the duration of the short term. Fantastic late summer/early fall weather for the region into early next week and well deserved after yet another stretch of exceptionally humid conditions. Enjoy. Temps...trended a bit closer to warmer MET guidance for highs both Sunday and Monday as abundant sunshine will support temps in the mid to upper 70s warming back to around 80 by Monday. Good setup for radiational cooling sets up for all three nights with some of our cool rural locales down near 50...especially Monday morning. && .LONG TERM /Tuesday through next Friday/... Issued at 223 AM EDT Sat Sep 10 2016 Ensembles in good agreement in bringing a short wave trough across the Great Lakes around the Tuesday night and Wednesday periods. Will keep some chance PoPs going in those periods to cover this system. Otherwise, it appears the upper pattern will amplify towards the end of next week, with deep troughing developing over the Plains, resulting in strong ridging over the eastern parts of the country. Ensembles suggest precipitation threat with this next trough will probably hold off until after this period, so will go mainly dry after Wednesday. && .AVIATION /Discussion for the 101500Z TAF Update/... Issued at 1026 AM EDT Sat Sep 10 2016 A few light showers will linger in the vicinity of KIND for the next hour or so. IFR ceilings should lift to MVFR soon. Satellite shows a break in the MVFR conditions that may move in later this morning, but for now kept things simple with no mention of a break. Additional convection could develop in the 17-20Z time frame, but still feel coverage will be too low to mention. Portions of previous discussion follow... Otherwise, cold front should be moving through the terminals during the early afternoon hours. Questionable whether convective temperatures will be reached in time for frontal passage, so don` think convective threat with the front is all that high later today. Areas of ceilings 012-025 expected prior to frontal passage, with ceilings lifting to a VFR deck 040-050 this afternoon after frontal passage. LIFR ceilings in the KLAF area should improve somewhat after precipitation begins. Surface winds 210-240 degrees at 8-11 kts this morning will veer around to 280-300 degrees later this afternoon in the wake of cold front. Occasional surface gusts 18-20 kts possible this afternoon. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....JAS AVIATION...JAS/50
Area Forecast Discussion
National Weather Service Northern Indiana
906 AM EDT SAT SEP 10 2016 .SYNOPSIS... Issued at 415 AM EDT Sat Sep 10 2016 Showers and thunderstorms are likely across the region again today ahead of a cold front that will usher in cooler and drier air for the second half of the weekend. It will remain humid into early afternoon but once the cold front passes and winds become northwest...it will begin to feel less humid. Highs today will range from the middle 70s northwest to the lower 80s southeast. Low temperatures tonight will be in the 50s. && .UPDATE... Issued at 859 AM EDT Sat Sep 10 2016 Forecast updated to bring higher pops in faster this morning and trend out slightly faster as well. Large area of rain was now well into the forecast area. Cluster of thunderstorms noted over central Indiana will move into SE parts of the area over the next couple of hours. HRRR/RAP continue the entire area east and north through the morning. Monitoring hydro concerns in several areas given heavy rain in some areas overnight, but luckily most areas hit last night are seeing generally light to moderate rain that should remain progressive enough to not add to any flooding issues but rather slow down any improvement. Still watching how things will unfold this afternoon with main line to initiate somewhere across eastern half of the area and moving into Ohio where instability should be better. Recent SWODY1 outlook only made minor changes to the slight risk area still just clipping Allen and now Putnam counties in Ohio with the marginal risk just east of I-69. && .SHORT TERM...(Today and Tonight) Issued at 419 AM EDT Sat Sep 10 2016 As we have discussed for the past several days...heavy rainfall and low end severe threat did indeed come to fruition thanks to tropical remnants from Newton and interaction with northern stream lead short wave. PWATs last evening in excess of 2 inches coupled with impressive mesolow/MCV and tropical airmass led to very efficient warm rain processes within low top supercell storms. Many areas received well over an inch of rainfall with some locations in excess of 3 to 4 inches. Attention now shifts to pcpn chances today as main northern stream trough approaches and pushes surface cold front through the area. Regional radar mosaic early this morning shows large area of rain with embedded tsra over MO and western IL expanding rapidly northeast ahead of synoptic system. HRRR experimental has a good handle on this precipitation and has verified quite well with short term pops over last few months. Have followed this models general trend for today. This suggests pcpn will reach western areas toward daybreak but begin to weaken/diminish as it moves east across the local area. Main cold front then follows early this afternoon with additional development of shra/tsra along it. The question will be how much we can destabilize behind initial pre-frontal showers and main front and where convection will begin to develop. Best chance for a strong or severe storm will be over mainly northwest Ohio where we could see some partial sun this afternoon and MLCAPES in the 1-2k j/kg range and 0-3km shear of 30-40kts. Considered a flood watch for today given overnight heavy rainfall but convection looks to be more scattered today so opted to hold off and allow day shift to monitor trends/development for more precise placement if needed. Once front clears the area late this afternoon should begin to see clearing with less humidity. A few models still trying to generate some light showers this evening post frontal with wrap around moisture but will only carry a slight chance pop early evening. && .LONG TERM...(Sunday through Friday) Issued at 419 AM EDT Sat Sep 10 2016 Broad area of high pressure to move in Sunday with much drier and cooler air. Dry weather expected through Monday night. Next chance for precipitation will be Tuesday and Tuesday night as fast moving short wave moves through the Great Lakes and associated cold front sags through the region. Kept pops in the low to mid chance range with best forcing north and limited moisture return as mid level ridge to our south blocks deeper moisture return. A refreshing Canadian airmass moves back in as high pressure slides through the Lakes. Highs in upper 60s to lower 70s and lows in the 40s look likely. Another system possible by Friday or Saturday with low chance pops for now. && .AVIATION...(For the 12Z TAFS through 12Z Sunday Morning) Issued at 647 AM EDT Sat Sep 10 2016 More showers and storms were headed over northern Indiana. Have updated the times of showers/storms in both TAFs as this next round moves over the area. There should be a break in the storms after this round until the front moves across the area. A lot of moisture and low clouds should persist early this morning with MVFR/IFR into mid morning, especially at SBN. Otherwise, conditions should become VFR behind the front by this evening. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement through Sunday morning for INZ003. MI...Beach Hazards Statement through Sunday morning for MIZ077. OH...NONE. LM...Small Craft Advisory until 11 AM EDT Sunday for LMZ043-046. && $$ UPDATE...Fisher SYNOPSIS...Lashley SHORT TERM...Lashley LONG TERM...Lashley AVIATION...Skipper Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
541 AM CDT SAT SEP 10 2016 .SHORT TERM... (Through Late This Afternoon) Issued at 336 AM CDT Sat Sep 10 2016 Cold front extending from northern IN southwest to just northwest of STL to just southeast of SGF will continue moving southeastward through the rest of the forecast area this morning as the upper level trough over the northern Plains moves eastward into the Great Lakes region. Large area of convection was moving through most of the forecast area early this morning producing high rainfall rates and periods of very heavy rainfall. Will continue the Flash Flood Watch across central MO into southwest IL including COU, JEF, FAM and the St Louis metro area until 12Z this morning. The latest HRRR model runs do show the stronger convective elements shifting east or southeast of our forecast area by 12Z Saturday with weaker scattered convection remaining this morning, then eventually shifting southeast of our area by afternoon. Despite a clearing sky later this morning and afternoon, high temperatures will be cooler than yesterday due to the low level cold air advection behind the cold front. Highs today will be about 5 to 10 degrees below normal. GKS .LONG TERM... (Tonight through Friday) Issued at 336 AM CDT Sat Sep 10 2016 (Tonight - Monday) This period will begin with northwest flow aloft and high pressure at the surface and transition by Monday to a W-SW flow aloft with southerly flow at the surface as the high pressure moves off to the east. This should equate to quiet wx, as temperatures start at below average values and recover to slightly above average by Monday. Nighttime min temps will reflect an early taste of autumn with anticipated readings in the upper 40s and lower 50s for most locations (higher in the STL metro heat island). Thanks to very little cloud cover during this period, daytime max temps will recover well Sunday and Monday, with temps near normal both days. (Tuesday - Friday) Rain chances return by late Monday night and continue into early Wednesday as a slow moving cold front drops thru. This represents the only wet period during this stretch with a surface high pressure building and dominating the region for late Wednesday thru Friday, with northeast to east surface flow, and should also return temps back to below average levels for mid to late next week. TES && .AVIATION... (For the 12z TAFs through 12z Sunday Morning) Issued at 529 AM CDT Sat Sep 10 2016 Cold front has pushed southeast of the taf sites early this morning. Showers should shift southeast of UIN and COU by 12Z Saturday, but will continue in the St Louis metro area until about 15Z this morning. MVFR cloud cigs should become VFR by 18Z today. Northwest surface winds today will become light this evening as a surface ridge moves southeastward into MO. SPECIFICS FOR KSTL: Cold front has pushed southeast of STL early this morning. Showers will continue in the STL area until about 15Z this morning. MVFR cloud cigs should become VFR by 18Z today. Northwest surface winds today will become light this evening as a surface ridge moves southeastward into MO. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Flash Flood Watch until 7 AM CDT this morning for Audrain MO- Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO- Gasconade MO-Jefferson MO-Lincoln MO-Moniteau MO-Montgomery MO-Osage MO-Saint Charles MO-Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-Warren MO- Washington MO. IL...Flash Flood Watch until 7 AM CDT this morning for Bond IL- Clinton IL-Madison IL-Monroe IL-Randolph IL-Saint Clair IL- Washington IL. && $$ WFO LSX
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
854 AM CDT SAT SEP 10 2016 .DISCUSSION...See updated information for land areas below. && .UPDATE...We have sent an update to the forecast to add a low chance of showers and thunderstorms across southern portions of southwest AL and the northwest FL Panhandle this morning. Regional radar imagery shows isolated to scattered showers and thunderstorms developing in the vicinity of southern Baldwin county, Mobile Bay and Dauphin Island this morning. This convection is developing within a moist and unstable environment characterized by a tongue of high precipitable water values of 1.8-1.9 stretching northward from the north central Gulf to coastal portions of the forecast area and MLCAPE values of 1000-1500 J/KG. Locally heavy rainfall and frequent lightning strikes may accompany some of the stronger storms this morning. Will continue to monitor trends, but no other updates are necessary at this point in time. /21 && .PREV DISCUSSION... /issued 628 AM CDT SAT SEP 10 2016/ DISCUSSION...Updated for latest aviation discussion below. AVIATION... 12Z issuance...Surface observations show patchy morning fog resulting in IFR/LIFR vsby and cigs over portions of the interior, while along the coast, patches of stratus are observed in lieu of fog. Morning fog will mix out shortly after sunrise with vsby improving quickly. A few to scattered fair weather cumulus is forecast to develop during the day with bases generally 2 to 4 kft. light northeast winds this morning become southeast to south during the afternoon. A very isolated shra/or a tstm possible this afternoon. /10 PREV DISCUSSION... /issued 331 AM CDT SAT SEP 10 2016/ NEAR TERM /Now Through Saturday night/...Upper air analysis this morning shows a vigorous mid-level trof pivoting eastward across the central and northern High Plains. The upper dynamics associated with this feature intersecting a surface frontal boundary draped from the upper Mid-West to the Red River Valley of TX/OK is bringing organized deep convection. The front makes steady southeast progress today into the Lower MS River Delta by this afternoon. The forecast area sees a narrow north to south mid-level ridge axis over the southeast between two upper level lows, one having moved into east TX and the other centered north of the Bahamas. For today as the front approaches the Lower MS River Delta, deep layer Gulf moisture is pulled northward, with precipitable water values improving to between 1.7 and 1.9 inches thru the day. Even so, the presence of the high level ridge remaining intact enough, acts to provide larger scale sinking motion. This offsets any weak lift that would develop as the airmass destabilizes. Will not totally discount a passing shower or storm, but potential of showers and storms will be kept minimal today with chances at or less than 10%, or very isolated in coverage. This is consistent with the latest high resolution HRRR and NAM-4KM solutions. Highs today range from 89 to 94. By tonight, the front mentioned earlier is forecast to enter the northwest zones this evening and begin to slow and eventually stall short of making it to the coast by daybreak Sun. Patchy late night fog possible with lows near 70 interior to the mid to upper 70`s beaches. /10 SHORT TERM /Sunday Through Monday night/...A weak upper trof over the extreme northwest Gulf and Louisiana continues slowly eastward into the forecast area through Monday night, becoming more diffuse in the process. A weak frontal boundary will be located over the forecast area on Sunday which dissipates Sunday night followed by a surface ridge building over the extreme southeast states on Monday. The surface ridge is weakened over the forecast area on Monday however, due to a surface reflection associated with the weak upper trof. The frontal boundary is expected to located over the interior portion of the forecast area on Sunday and have gone with chance pops for most of the area except for slight chance pops closer to the coast. Identifying the portion with the best convective potential is more difficult on Monday given the weak surface reflection from the weak upper trof, and with a favorable convective environment have gone with chance pops for now for essentially the entire area. Highs will mostly be in the lower 90s with upper 80s near the coast, although some inland locations may see the mid 90s on Sunday. Lows will be in the lower 70s except for mid 70s near the coast. /29 LONG TERM /Tuesday Through Friday/...The weak and diffuse upper trof over the forecast area finally dissipates on Wednesday with upper ridging building into the region and eastern states through Thursday. There continue to be indications of a poorly defined surface reflection over the area on Tuesday, and have continued with chance pops for the area. Another weak frontal boundary may move into the area Wednesday into Thursday and linger through Friday and have gone with slight chance to chance pops. Highs will be in the lower 90s through Thursday with upper 80s near the coast, then somewhat cooler highs follow for Friday ranging from near 90 inland to the mid 80s at the coast. Lows will be in the lower 70s except for mid 70s near the coast. /29 MARINE...Weak surface high pressure holds into the southeast thru the weekend. A weak frontal boundary sinks southward across the Lower Mississippi River Delta today. The frontal boundary looks to stall just short of the coast by Sun and remain nearly stationary into the beginning of next week. Winds mostly light and becoming onshore today and Sun with little change in seas, 2 feet or less. For Mon thru Wed, high pressure sets up along the east coast and southeast US resulting in an easterly fetch. Isolated to scattered showers and storms. /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 Marquette MI
742 AM EDT SAT SEP 10 2016 .SHORT TERM...(Today and tonight) Issued at 418 AM EDT SAT SEP 10 2016 00Z raobs/latest wv imagery and RAP analysis shows a deepening upr trof over the Ncentral Conus with a fairly strong shrtwv lifting out of the base of this trof into the Upr MS river valley. Since the forcing associated with this feature has not yet interacted with an axis of hier pwat /up to 1.5 inches per SPC analysis/ and weak sfc- h85 troffing stretching fm Scentral WI into Ern Upr MI, numerous showers are present over the far SE cwa along the axis of hier mstr. Sct-numerous showers are present over wrn Upr MI into MN ahead of cold fnt associated with the shrtwv. Temps are fairly warm early this mrng with 00Z h85 temps 16C at GRB/APX. H85 temps within the thermal trof over the nrn plains behind the cold fnt are as lo as 6- 8C. There are numerous fcst concerns in the short term, including pops and then winds associated with a sfc lo pres that is fcst to dvlp and intensify on the trof axis just to the SE ahead of the incoming shrtwv. Early this mrng/today...As shrtwv to the SW lifts into the Upr Lks, vigorous dpva/deep lyr qvector cnvgc and upr dvgc ahead of this disturance and in RRQ of 120kt h3 jet max near James Bay should be sufficient to result in a rapid expansion of the showers, espcially over the E half of the cwa closer to the sfc-h85 trof and hier pwat. The GFS has been fairly consistent showing an axis of strengthening h85-7 fgen/uvv over this part of the cwa on the wrn flank of the trof axis this mrng. So wl fcst the hiest categorical pops/pcpn amnts/with embedded TS in the presence of SSI down to about -1C in this area. Fortunately, this band of sharper forcing is fcst to lift fairly quickly to the NE and into SE Ontario toward 15Z. But lighter rains wl persist until the deep lyr qvector cnvgc/hier h85-5 RH lift out to the NE as well after 18Z. With the arrival of deep lyr qvector dvgc/subsidence/mid lvl drying during the aftn, there should at least be partial clrg over the W half of Upr MI. Models continue to show sfc cyclogenesis as well on the trof axis with more rapid dvlpment occurring once the sfc lo exits to the E. The 00Z NAM is strongest with the NNW winds that are fcst to dvlp on the wrn flank of this departing sfc lo pres, with h925 winds fcst up to 35 to 40 kts in areas E of Munising/Grand Marais. With an influx of the cooler air to the NW over the relatively warm waters of Lk Sup, the setup seems favorable for very gusty winds at least close to advy criteria. But most of the other models are weaker with the fcst wind speeds, so wl hold off on any headlines for now and continue going special wx statement for Alger/Luce counties for gusty winds to arnd 40 mph and some beach erosion accompanying the bldg waves/above normal Lk Sup water lvls. These hi waves wl contribute to a hi swim risk along the Lk Sup waters fm Marquette County to the E. Tngt...The strong NNW winds over mainly the Ern cwa wl diminish this evng as the lo the E exits into Quebec and sfc hi pres blds toward the area under quickly rising h5 hgts ahead of an aprchg shrtwv rdg. The incoming airmass, with h85 temps down to 5C, wl probably be sufficiently cool to maintain some lk clds over the Keweenaw and the E, but fcst sdngs sug the near sfc lyr wl be too dry for any pcpn. Influx of cooler air wl drop min temps into the 40s away fm moderation off Lk Sup. .LONG TERM...(Sunday through Friday) Issued at 257 AM EDT SAT SEP 10 2016 Prior to a cold front moving through, Sun and at least most of Mon look pleasant with mostly clear skies, highs in the 70s and lows in the 50s. That front will bring chances for precip Late Mon into early Tue depending on shortwave energy and moisture availability. Behind the front, a shortwave trough may move through on Tue, combining with NNW winds and 850mb temp AOB 7C to bring isolated-scattered showers. Highs on Tue will be in the upper 50s to mid 60s, warmest SE. 850mb temps could fall to near 0C Tue night as a SFC high moves in. The cold temps will initially lead to lake effect clouds and isolated showers, but those should be diminishing as the dry high moves in. Certainly potential for a hard freeze over the interior W, but for now have lows down to 32F. Airmass temps look to rebound to 10-12C late in the week. There is potential for precip Fri-Sat, but confidence is very low. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 741 AM EDT SAT SEP 10 2016 Some lo clds will plague the TAF sites thru this mrng under a relatively moist and incrsg NNW flow behind a passing cold fnt. Expect the worst IFR cigs at IWD with a more pronounced upslope wind component. Some moderate ra wl also reduce vsbys into the MVFR range at times. Gusty NNW winds by this aftn wl grdly draw drier air into the area, allowing conditions to improve to VFR at SAW by late in the aftn. As hi pres slowly blds toward the area tngt, the winds wl diminish and VFR wx wl persist. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 418 AM EDT SAT SEP 10 2016 A cold front is moving across Lake Superior early this morning, with winds shifting to the NNW in its wake. As a lo pres moves thru eastern Upper MI this morning and deepens over SE Ontario today, expect the NNW winds to increase up to 30 kts over much of the E half of the lake. Since widespread gales do not appear likely, opted to drop the previous gale watch. But there could still be some gale force gusts over the eastern portion of the lake this afternoon into the evening before the lo pres moves farther away and an approaching hi pres ridge cause the winds to diminish tonight into Sun. As the hi pres shifts to the E and a tighter pres gradient develops again on Sun night into Mon ahead of an approaching cold front, expect SSW winds to increase up to 30 kts. Winds will shift back to the NNW late Mon into Tue following the cold frontal passage, but these winds are not expected to be higher than 20 kts. Winds will diminish and back to the W as trailing hi pres moves thru the Western Lakes on Wed. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement from 11 AM EDT this morning through this evening for MIZ005-006. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...KC LONG TERM...Titus AVIATION...KC MARINE...KC
Area Forecast Discussion
National Weather Service Paducah KY
647 AM CDT SAT SEP 10 2016 .UPDATE... Issued at 647 AM CDT Sat Sep 10 2016 The AVIATION section has been updated for the 12Z TAF issuance. && .SHORT TERM...(Today through Monday) Issued at 321 AM CDT Sat Sep 10 2016 The consensus of HRRR runs over the last few hours take the area of convection over the St Louis metro area northeastward, which may bring a stray shower or storm into the northwest corner of Perry or Jefferson county through sunrise. Farther southwest, they indicate continued weakening of the former convective band over southwest Missouri as it approaches our western counties by sunrise. There may not be much of this left at all, but will have a band of 20-30% PoPs moving eastward across the entire area through 16Z or so, associated with the outflow boundary. There could be some increase in convective development along this boundary over west Kentucky mid to late morning. The cold front will be approaching the Ohio and Wabash Rivers by midday, and this is when convection should begin to develop near it. The primary window east of the rivers will be 18Z-20Z. Figure that it will eventually result in a fairly solid line over the Pennyrile, but it may be more scattered initially. Cannot argue with SPC`s Marginal Risk of severe weather along and east of a line from Murray to Owensboro. Surface-based instability should be somewhere in the vicinity of 2000J/kg, but wind fields will not be that strong. There will be some deeper layer shear, albeit unidirectional, but not much low-level shear. Look for some damaging wind potential with the line or line segments in the early to mid afternoon. The storms should be moving along quickly enough to limit the impact of locally heavy rainfall. All indications are that this activity will be east of the area by 22Z, but kept some smallish PoPs in the southeast corner of the region til sunset. After this convection exits the area, it will be much cooler and drier for the remainder of the short term period through Monday. Stayed close to the consensus of all available guidance for highs today and lows tonight and Sunday night. Favored the slightly warmer consensus MOS numbers for highs Sunday and Monday, due to the sunny and dry conditions expected. .LONG TERM...(Monday Night through Saturday) Issued at 321 AM CDT Sat Sep 10 2016 There is fairly high forecast confidence in the extended periods of this forecast. The medium range models continue to trend drier for much of the work week with high pressure at the surface and aloft continuing to influence the region. Surface high pressure will keep the low-level wind fields muddled heading into Wednesday, as a cold front approaches the area. This effectively causes the cold front to dissipate, leaving just a re-inforcing surge of high pressure to sweep through the area Wednesday. We may see some scattered convection reach the far northwest portions of the forecast area late Tuesday night, but all indications are that any convection will dissipate over our northern territories Wednesday morning. Will continue with only 20-30% PoPs for this potential. The forecast then is dry through Thursday night. The 00Z ECMWF and GFS bring a good portion of a former closed low over the Inter-mountain west northeast into the Upper Midwest Friday into Saturday. This could eventually bring a decent chance of convection into our region Friday, and most likely on Saturday. This will be determined by how quickly the east coast upper high gets suppressed to the southeast Atlantic coast. Will have slight chances on Friday increasing to decent chances on Saturday. Temperatures should be at or above normal Tuesday and Wednesday, but will drop just a shade below normal for Thursday and possibly Friday. Saturday could see warmer temperatures, but only if the convection holds off. && .AVIATION... Issued at 647 AM CDT Sat Sep 10 2016 Scattered showers may reach KCGI, KEVV and possibly KOWB this morning, as an outflow boundary passes through the region. An MVFR ceiling will be possible at KCGI as well. A larger-scale cold front will move across the TAF sites this afternoon. Scattered thunderstorms are expected to develop in the vicinity of KEVV and KPAH around 17Z, and then push eastward through KOWB an hour or two later. Not sure how far west they will get going, or how much coverage there will be by the time they clear KOWB, so just went with a VCTS. There could be some gusts up to 20kts from the southwest ahead of the front late this morning, and from the northwest behind it this afternoon. A light northwest wind and drier air over the region should prevent fog formation tonight, despite the rather strong signal in the most recent guidance. && .PAH Watches/Warnings/Advisories... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS SHORT TERM...DRS LONG TERM...DRS AVIATION...DRS
Area Forecast Discussion
National Weather Service Albany NY
344 PM EDT SAT SEP 10 2016 .SYNOPSIS... Scattered showers and thunderstorms are expected tonight as a strong cold front crosses the region. Cooler, drier and breezy conditions are expected for Sunday. Then a period of very tranquil weather is in the forecast for early next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... For tonight...Expect scattered showers and thunderstorms to become more numerous as the night progresses ahead of a strong cold front which will be crossing the region late tonight. A very strong pressure gradient is in place ahead of the cold front which will produce some strong gusty winds with any thunderstorms. ECMWF hints at the rain band ahead of the front becoming more organized across eastern New York as a strong vort max rotates around the base of the H5 trough. Looking at some of the parameters overnight...MLMUCAPES remain between 500 and 1000 J/kg for much of the night, 0-6 km bulk shear is impressive at 40-70 kts thus the potential for some strong wind gusts, H8-H7 lapse rates higher than earlier model runs now at 5-7 C/km late tonight and finally PWATS between 1.5 and 2.1 inches so certainly some heavy downpours possible. HRRR composite reflectivity shows a line of fairly strong convection moving across the forecast area between 06z and 10z. Overnight lows tonight are expected to remain very mild with readings in the upper 50s to mid 70s with dewpoints remaining in the 60s to lower 70s for much of tonight. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... on Sunday...After any showers end early in the morning expect clearing with breezy and much less humid conditions. Highs on Sunday will be in the mid 60s to lower 80s with dewpoints dropping into the upper 40s to mid 50s by days end. Winds will be west at 10 to 20 mph with gusts to 30 mph. Sunday night through Monday night...A large ridge of high pressure will crest over the region early Monday morning and slide off the eastern seaboard early Tuesday morning. Expect much more seasonable conditions. Lows Sunday night are expected to be in the 40s to around 50 with highs on Monday in the upper 60s to upper 70s and lows Monday night in the upper 40s to mid 50s. Tuesday...Expect milder conditions once again as a return flow sets up wit high pressure off the coast. It will still be dry, but highs will rebound to the mid 70s to lower 80s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The period starts out Tuesday night with a cold front and its associated upper level trough approaching from the Great Lakes region. There are some timing differences in the model guidance, with the 12Z/10 GFS showing faster timing compared to the 12Z/10 ECMWF, which is a reversal from 00Z/10 guidance. Allowing for a margin of error in timing, will mention slight to low chance pops ahead of the front for areas north and west of the Capital District starting late Tuesday night. A better chance for showers will be during the day Wednesday as the front and upper trough axis push through. Will only mention slight chance of thunder due to forecast limited surface based instability, but slightly negative Showalter values. The ECMWF suggests that showers may linger well into Wednesday night, so will keep chance pops at least into the evening hours, especially for northern areas. It will then turn much cooler and drier from Wednesday night through the end of the work week, as a sprawling area of surface high pressure builds in across the region. Temperatures will feel more fall-like with cool crisp nights and seasonably warm sunny days Thursday and Friday. By Saturday, the high will begin shifting off the eastern seaboard, with a moistening southerly developing. In addition, another frontal system will be approaching from the Great Lakes. Some showers may reach the region by late Saturday or Saturday night, especially for areas north and west of Albany, where slight chance pops are indicated. As for temperatures, Tuesday night should be mild ahead of the front, with lows ranging from the 50s across higher terrain, to the lower/mid 60s in valleys. Wednesday high temperatures are forecast to range from the 60s across northwest areas, to the upper 70s/lower 80s southeast valleys. If the front moves through slower, even warmer high temperatures are possible, especially southeast areas. The cooldown begins Wednesday night, with lows in the 40s for most areas, except for some lower 50s in valley areas. Thursday highs should be quite cool, with mainly 60s expected for most areas, except for 50s across higher elevations of the Adirondacks and southern VT, and lower 70s across southeast valley areas. Thursday night/Friday morning will be chilly, with patchy frost possible across portions of the western Adirondacks, southern VT, and higher peaks in the Catskills, with upper 30s to lower 40s expected in these areas, and lower 40s to around 50 elsewhere. Slight warming for Friday and Saturday, with temperatures reaching 70s in valley areas, and 60s for higher elevations. Overnight lows will be in the mid 40s to mid 50s. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... A warm front will lift northward early this afternoon. A cold front will then sweep eastward across the TAF sites early Sunday morning. Scattered showers associated with the warm front may impact KGFL through around 19Z/Saturday. Otherwise, expect only isolated showers/thunderstorms for the remainder of this afternoon into early tonight. Since areal coverage will be minimal, will keep out any mention in TAFs at this time, and amend as necessary based on radar trends. There will be a renewed chance for showers and even some thunderstorms late tonight ahead of and along a cold front approaching from the west. However, most of the activity is not expected to reach the terminals until around or after 06Z Sunday, so will only mention VCSH for now until confidence increases. The cold front should sweep across the TAF sites roughly between 11Z-13Z/Sunday. Showers/thunderstorms should taper off in its wake, with clearing skies developing by late Sunday morning. As for overall flight conditions, mainly VFR outside any isolated showers/thunderstorms through early tonight, and briefly MVFR/IFR in any passing shower/thunderstorm. Some patchy MVFR cigs may develop later tonight ahead of the cold front, especially at KPSF. Also, pockets of MVFR/IFR will remain possible with any showers/thunderstorms. After the front passes Sunday morning, VFR conditions are expected. Winds will become south to southeast this afternoon and increase to 5-10 KT, with some gusts possibly up to 20 KT, especially at KALB. Winds will be south to southwest tonight at 5-15 KT, with some gusts of 20-25 KT possible, especially at KALB. Winds will then shift into the southwest, then west as the front passes and increase to 10-15 KT with gusts up to 25 KT possible by late Sunday morning. Low level wind shear may become problematic later this evening through early Sunday morning, as winds around 2000 FT AGL increase from the south/southwest at 35-40 KT. This issue will be mainly in areas where surface winds decrease to less than 10 KT, which at this time, appears most likely at KGFL, where it has been included in TAFs. Outlook... Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA. && .FIRE WEATHER... Scattered showers and thunderstorms are expected tonight as a strong cold front crosses the region. Cooler, drier and breezy conditions are expected for Sunday. Then a period of very tranquil weather is in the forecast for early next week. Relative humidity values will recover to 85 to 100 percent tonight, drop to 40 to 65 percent on Sunday, recover to 80 to 100 percent Sunday night, and drop to 35 to 45 percent on Monday. Winds will be south to southwest at 10 to 20 mph with gusts to 30 mph tonight, west at 10 to 20 mph with gusts to 30 mph on Sunday, northwest at 5 to 15 mph Sunday night, and west around 5 mph on Monday. && .HYDROLOGY... Showers and thunderstorms are expected tonight. Some heavy downpours are possible which may produce flooding of poorly drained low lying areas. However, no flooding is expected on the main stem rivers. QPF amounts through tonight generally look to be between a quarter of an inch and an inch in most locations. Dry weather is then expected to return later Sunday morning and last at least through Tuesday. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...11/NAS NEAR TERM...11 SHORT TERM...11 LONG TERM...KL/JPV AVIATION...KL/JPV FIRE WEATHER...11 HYDROLOGY...11/NAS
Area Forecast Discussion
National Weather Service State College PA
308 PM EDT SAT SEP 10 2016 .SYNOPSIS... Low pressure will track northward through the Great Lakes today, pushing a trailing cold front through central Pa tonight. High pressure will build into Pennsylvania Sunday and continue through early next week. A new cold front will push south across the region Wednesday, followed by another high pressure system with cooler temperatures again for late in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A very warm and humid day is in progress. SPC meso anal shows mixed layer Capes in the 1000-1500J so there is some instability developing in the airmass out ahead of the cold front that is just entering western Ohio. However local forcing and lapse rates remain weak so little more than scattered pulse type activity is expected for the bulk of the region during the daylight hours. The HRRR shows the leading edge of a squall line entering Warren County by 8PM, and it progresses east into the western portion of the CWA before the model shows the convection diminishing in coverage and intensity, which makes sense wince we will tend to see stability increase after we lose the diurnal heating. Highest pops will be over the Laurels up into the northern mountains with chances dropping off over central and eastern areas. Ahead of the cold front it will be a warm and muggy night over most areas with lows averaging 10-15 deg above normal. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Sunday looks like a beautiful and increasingly less humid day as high pressure is slated to build east out of the midwest. 12Z deterministic models show a small area of very light QPF over the northwest Sunday morning in the wake of the cold front, but the SREF/GEFS show low to no pops. So while I won`t rule out a lingering light shower or sprinkle, I chose an optimistic dry forecast. Sunday`s highs will be some 10-15 deg cooler than today. Closer to seasonal normals. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Not a lot of change for this section of the package. Monday looks like a cooler and sunny day, as heights rise and the high builds east of the area. Still looks mainly dry on Tuesday, but hints at low level moisture works northward. There could be a very brief sprinkle late. A very warm airmass works eastward ahead of the next cold front on Wednesday. Thursday and Friday look dry. Some hints of showers for Saturday, thus have some chc in fcst. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... Low pressure will track northward through the Great Lakes today, pushing a trailing cold front through central Pa tonight. VFR will continue into the evening. A cold front will trigger an advancing line of showers and thunderstorms that will move into the NWRN mountains by evening, bringing locally reduced conditions. The showers and thunderstorms will tend to fall apart as they move into the central mountains so MVFR/IFR will also tend to become more scattered as the convection diminishes. More widespread restrictions, mainly lower ceilings, are expected behind the front tonight, mainly over central and western terminals. Conditions will improve rapidly after sunrise Sundayas a gusty and drier NW breeze develops. Outlook... Mon-Tue...No sig wx. Wed...Chc shra/tsra. Thu...no sig wx. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Martin NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...Martin AVIATION...La Corte
Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Sunday Issued at 231 PM CDT Sat Sep 10 2016 The latest RAP analysis and satellite/radar imagery show broad low pressure and an associated cold front moving east over Michigan early this afternoon. The band of showers behind the front has exited to the east, but additional shower activity and isolated thunderstorms have developed beneath a cold upper trough that is moving across the region. These showers should impact the region through the end of the afternoon before ending/exiting. Looking upstream, surface high pressure is bringing clearing skies over the northern Mississippi Valley. Additional mid and high clouds are sliding southeast over the western Dakotas, but no sign of precip associated with them. Precip and cloud trends are the main forecast concern in the short term. Tonight...A few showers may linger along the lakeshore areas early this evening before moving over the Lake. Otherwise, should see clearing skies take place as high pressure drifts into the region. Though mid and high clouds will be arriving late, recent rainfall and low temp/dewpoint spreads could lead to patchy fog developing late over north-central WI and the WI River Valley. Lows ranging from the mid 40s north to low 50s south. Sunday...High pressure will quickly advance across the region during the morning hours. Will see some scattered to broken mid and high clouds through the morning and into the afteroon, so sky conditions will likely fall into the partly cloudy range for most areas, but with increasing sunshine in the afternoon. High temps ranging from the low to mid 70s. .LONG TERM...Sunday Night Through Saturday Issued at 231 PM CDT Sat Sep 10 2016 Northern stream flow will dominate the regions weather for much of new work week. A short wave trough with frontal system will slide over the Great Lakes region later Monday into Tuesday. 850 warm prod does produce steep mid level lapse rates Monday afternoon but saturation appears to be a problem initially. As the air mass begins to saturate later Monday evening the best instability and 850 warm air advection is pushed to the south. With the RRQ region of the upper jet for large scale ascent just to the west and the 850 front and baroclinic zone dropping south over the state later monday night into tuesday morning, anticipate a better chance for showers. Could have more of band of steady rain event if the if the upper jet support is a bit more eastward. Upper heights build for the mid week ahead of western states trough. A high pressure system drifts over the area for another dry period with temperatures returning to near normal. Medium range progs indicate a short wave from the western states trough gets into the northern stream late in the week for the next chance for precipitation. Timing of this system could be delayed into the start of next weekend. && .AVIATION...for 18Z TAF Issuance Issued at 1142 AM CDT Sat Sep 10 2016 Low pressure will be exiting the region to the northeast this afternoon. However, scattered showers will linger through the end of the afternoon over north-central and northeast WI. Mvfr cigs will likely persist over north-central WI, and within any shower activity. Then clearing is expected to occur from west to east early this evening. With mostly clear conditions and diminishing winds, patchy fog could form in the low lying areas and river valleys over central and north-central WI late tonight. High pressure will be in charge for Sunday, yielding good flying weather for the region. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......MPC
Area Forecast Discussion
National Weather Service Grand Rapids MI
701 PM EDT SAT SEP 10 2016 LATEST UPDATE... Marine .SYNOPSIS... Issued at 324 PM EDT Sat Sep 10 2016 Dry conditions and lower humidities are expected through Monday night. The next chance for showers and thunderstorms comes Tuesday and Tuesday night. This will be followed by generally dry conditions the rest of the work week. Temperatures through the period will be much more seasonable with highs in the 70s. && .SHORT TERM...(This evening through Monday night) Issued at 324 PM EDT Sat Sep 10 2016 This evening...main challenge is timing exit of precipitation. Most of the high resolution convection allowing models such as the HRRR are in decent agreement about timing and also with indicating a window of lake effect rainshowers until around midnight before winds become lighter and more anticyclonic. Sunday through Monday night...high confidence of dry conditions with rain chances approaching from the northwest overnight Monday. .LONG TERM...(Tuesday through Saturday) Issued at 324 PM EDT Sat Sep 10 2016 There are two major issues with this forecast... first and foremost... it will be noticeably cooler through this coming week and well beyond that. The other issue is the cold front that comes through Tuesday into Wednesday. That will have a band of showers and maybe a thunderstorm or two with it but I do not expect much rain from this system... mostly it will just bring in even cooler temperatures. From this point forward it will feel more fall like in Southwest Michigan. At GRR highs have frequently been in the 80s since the 23rd of May. Yesterday it got to 83...well guess what... the string of days with highs mostly in the 80s is done for the year. With this cold front (Saturday) from this point forward highs will mostly be in the 70s and occasionally in the 60s. Not to say we could not have the odd day with highs in the 80s yet. The frequently of highs in the 80s at GRR by day is around 50% (1892 to 2016) by the 14th that drops to 27% and by the 25th it is less than 10% of the days. To me this is the most significant change in our daily weather this coming week...highs will only 70s. The really warm weather is done for the year. What is curious about that through is the subtropical ridge is expected to build westward into the central and even northern plains by the end of this coming week. That will force the next Pacific system to track farther north and not allow us to get as deeply into the cooler air. Even so it will still get cooler behind this cold front that the one coming thought today. The polar jet...which is over Michigan today into tomorrow shifts north into central Canada by the end of this coming week. That will lead to a warm up toward next weekend but with a southern stream system coming at us by then...it may well be a wet one too. With the polar jet farther north with the cold frontal system coming through Tuesday night into Wednesday the dynamics will also be farther north and there will not be nearly as much moisture for this system as has been available to that last few systems. So rainfall will be more scattered and significantly lighter. So the bottom line is cooler weather and much lower outside humidities. The best chance for showers will be Tuesday night into Wednesday morning then again Saturday (could be a very wet day). && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 130 PM EDT Sat Sep 10 2016 There is a classic narrow frontal rain band ahead of the cold front crossing Lower Michigan (near US-131 at 1730z)as I write this. Locally heavy showers (no thunderstorms) are embedded in the rain band. Overall MVFR during the time of the passage of this rain band....there may be brief periods of IFR in the heavier showers (no thunderstorms). Once the front is through winds will swing to the northwest and gust to around 30 knots at times into early evening. After the rain band and front are through the area (21z to 00z) conditions should become VFR and stay that way through Monday. It should be noted through for the GRR and MKG TAF sites...there is enough instability just behind the front that there could be lake effect showers and thunderstorms from 21z till around 03z or so. I put VCTS for those taf sites. && .MARINE... Issued at 700 PM EDT Sat Sep 10 2016 Have updated the Nearshore Marine Forecast to include a mention of thunder and a chance of waterspouts this evening. Mid level trough and cold pool are coming through this evening and a few cells over the lake have already had some lightning. Waterspout nomogram, using a lake to 850 temp diff of 15C and a Cloud depth of 15-20K ft, supports a few spouts. Also there have been some reports of funnels on the Wisconsin side recently. Previous marine discussion... We saw an impressive burst of winds at many of the buoys and coastal sites with the cold frontal rain band that passed through. We expect a brief lull in winds this afternoon, but expect them to increase again this evening. Latest WaveWatch3 guidance does a decent job depicting this and it appears that a 8AM Sunday expiration for the SCA and Beach Hazards still looks reasonable. && .HYDROLOGY... Issued at 211 PM EDT Sat Sep 10 2016 Rivers are running at or above normal for the time of year. Showers and storms will continue through the afternoon. Less than a half inch of precipitation is expected across the area through the week. Small river rises are possible, but flooding is not expected. && .GRR Watches/Warnings/Advisories... MI...Beach Hazards Statement through Sunday morning for MIZ037-043- 050-056-064-071. LM...Small Craft Advisory until 8 AM EDT Sunday for LMZ844>849. && $$ SYNOPSIS...TJT SHORT TERM...TJT LONG TERM...WDM AVIATION...WDM HYDROLOGY...63 MARINE...Meade
Area Forecast Discussion
National Weather Service Huntsville AL
326 PM CDT SAT SEP 10 2016 .DISCUSSION... A more amplified mid/upper pattern was in place across the greater North American domain this afternoon. A progressive trough moving to the SE was a big feature over the central and eastern CONUS, with convection forming in the vicinity of a cold front that extended from the central Great Lakes, eastern Arkansas and Texas Hill Country. Closer to the area, those showers/thunderstorms were affecting areas from near Louisville KY to NW of Ft Campbell and Memphis. Closer to home - despite earlier morning and early afternoon cumulus and towering cumulus development, little in the rainfall department thus far for the local area. Drier air/subsidence aloft in the mid levels of the atmosphere has thus far kept a lid on showers forming. Mid afternoon temperatures under partly sunny skies have risen into the low/mid 90s with 5-15 mph SW winds. Short/longer term model output, at least in the shorter term has indicated isolated to scattered showers and t-storms affecting much of the Tennessee Valley late this afternoon and this evening. Per the latest HRRR and RAP, timing of this activity affecting NW Alabama is around 5-6 PM, then progressing to the SE and weakening during the nighttime. The NSSL-WRF and HiRes ARW show similar timing, but in similar agreement with the NAM/GFS/ECMWF, hint that the activity should diminish in coverage/intensity as we go in the late night and Sunday morning. As such, stayed with scattered (rather than higher) rain chances this evening. In the wake of the frontal passage tonight, dry weather with slightly drier and cooler high temperatures (about 5 degrees cooler than today) will start a new week. Notably cooler conditions are forecast for Sunday night, with lows ranging from the upper 50s in portions of NE Alabama and Southern Middle Tennessee to the lower 60s elsewhere. The dry weather should continue into Monday with highs once again warming back to around 90. Very warm weather will continue on Tuesday, however a return of Gulf moisture (in part through the former cold front becoming diffuse to our south), will bring a slight chance of showers/thunderstorms. Another weak cold front should bring a wind shift and not much rain for the mid week. Given our on-going dry spell, stayed dry for the Wed night through Thu night time-frame, closer to the ECMWF solution. For the end of next week, longer term guidance continued to hint at a deeper SE flow across the region, preceding another stronger cold front (that should pass across the area sometime early next week). The deeper moisture and instability should yield somewhat better chances for showers and thunderstorms next Fri/Sat. Precip water amounts from the GFS rise towards the 2 inch range, suggestive for locally heavy rains. That would help alleviate dry conditions much of the Tennessee Valley continues to be affected by. RSB && .AVIATION... (Issued 1229 PM CDT SAT SEP 10 2016) For 18Z TAFs: VFR conditions are expected with isolated -SHRA activity that is occurring across portions of N AL as a cold front approaches from West TN/MS River area. WNW winds up to 10 kts are currently expected to prevail until around 10/20Z-10/22Z with winds veering to NNW. Isolated to Scattered -TSRA are possible with the approach and in the vicinity of the front btwn 10/20Z-11/01Z and have kept VCTS for now due to uncertainty with areal coverage near the terminals. Any of these -TSRA may cause gusty winds up to 30 kts. After frontal passage NE winds up to 10 kts and mostly VFR-MVFR cigs are anticipating before clearing later in period. SL.77 && .PRELIMINARY POINT TEMPS/POPS... Huntsville 68 87 62 91 / 40 10 0 10 Shoals 67 85 60 89 / 30 10 0 0 Vinemont 67 85 63 89 / 30 10 0 10 Fayetteville 65 85 59 88 / 40 10 0 10 Albertville 68 86 62 88 / 20 10 10 10 Fort Payne 67 86 63 88 / 20 10 10 10 && .HUN Watches/Warnings/Advisories... AL...NONE. TN...NONE. && $$ For more information please visit our website at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Jackson MS
358 PM CDT SAT SEP 10 2016 .SHORT TERM...Today through Monday...An upper-level shortwave trough is sliding eastward across the country this afternoon, while a cold front at the surface trails from a surface low over the Great Lakes southwestward to East Texas. A moist airmass remains in place to the east of this front, and a fair amount of instability has developed along it with afternoon heating. RAP analysis currently indicates around 2000 to 2500 J/kg of MLCAPE in the far northwest of our CWA. A line of showers and thunderstorms will advance with the front through the evening hours, with POPs declining overnight. Though not a particularly strong cold front, temperatures should be a few degrees cooler and dew points should be a few degrees lower tomorrow for locations north of the Interstate 20 corridor. Locations to the south of Interstate 20 will generally stay on the warmer and humid side similar to recent days./NF/ .LONG TERM...Tuesday through Saturday...A mid to upper level ridge of high pressure is expected to build back over the southeastern CONUS by early next week and last though most of the week. The ArkLaMiss should remain generally on the humid southern edge of this ridge with forecast PWAT values around 2 inches continuing across the region. Have kept temperatures a few degrees above normal and POPs favoring the southern and western portions of the area through the extended periods given the expected pattern. Models indicate that anothernorthern CONUS trough/closed low will be moving across the country near the end of next week, which should allow for another decent shot at more widespread precipitation across the region./NF/ && .AVIATION...VFR conditions will continue to prevail areawide today. Showers have developed this afternoon both in eastern Mississippi and more tracking toward the northwest Delta, ahead of an approaching cold front. Any SHRA(or isolated TSRA) could bring brief periods of MVFR conditions through this evening. Winds at northern TAF sites will shift out of the north behind the front./28/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 73 88 70 91 / 41 37 7 22 Meridian 72 91 70 92 / 39 40 13 25 Vicksburg 72 89 67 92 / 42 24 4 19 Hattiesburg 73 91 72 91 / 27 56 16 37 Natchez 71 87 70 89 / 33 43 12 29 Greenville 68 86 63 90 / 24 10 2 11 Greenwood 69 87 65 91 / 27 10 2 11 && .JAN Watches/Warnings/Advisories... MS...None. LA...None. AR...None. && $$ 06/06/28
Area Forecast Discussion
National Weather Service Marquette MI
407 PM EDT SAT SEP 10 2016 .SHORT TERM...(This evening through Sunday) Issued at 406 PM EDT SAT SEP 10 2016 12Z raobs/latest wv imagery and RAP analysis shows fairly strong shrtwv lifting e through the Upper Great Lakes. Combination of deep layer q-vector convergence ahead of this shortwave and NNW flow off Lake Superior bringing h85 temps of 6-7C across the lake sustaining sct to numerous showers/lake enhanced showers over the ern two thirds of Upper Mi this afternoon. Suspect this showers will persist into the early evening hours before best dynamics exit e with departing shortwave. Tonight and Sunday...The strong NNW winds gusting to 30-35 mph over mainly the Ern cwa wl diminish later this evng as the sfc low exits ne into Quebec and sfc hi pres builds toward the area under quickly rising h5 hgts ahead of an approaching shortwave ridge. The incoming airmass, with h85 temps down to 5C, wl probably be sufficiently cool to maintain some lake clouds over the Keweenaw and the E into this evening, but fcst soundings suggest the near sfc lyr wl be too dry for any pcpn. Influx of cooler air wl drop min temps into the 40s away fm moderation off Lk Sup. Min temps near 40F possible over the western interior. Sfc ridging and anticyclonic sw flow ahead of an incoming cold front will result in a pleasant Sunday under mostly sunny skies. Expect highs in the lower to mid 70s across much of the forecast area. .LONG TERM...(Sunday night through Saturday) Issued at 357 PM EDT SAT SEP 10 2016 Sunday night through Monday: A surface ridge and drier air will be in place with anticyclonic flow across the Upper Great Lakes Sunday night. This will keep mostly clear skies in place across the U.P. with fairly light westerly winds. Aloft, nearly zonal flow will be in place through this time period. Monday, the high center will slide to the east, allowing warmer and more moist southerly flow to push back into the Upper Great Lakes region. This will happen at the same time that low pressure slides from central Canada eastward to near James Bay. A cold front will extend southwest from the low into the Arrowhead of MN by Monday afternoon. The main impacts from this in the U.P., for Monday afternoon, will be increasing cloud cover over the west with a few showers. Monday night through Tuesday night: The aforementioned low pressure center will slide from near James Bay Monday evening to northeast Quebec Tuesday night. As this happens, the cold front will slide southeastward into the western U.P. Monday evening, the eastern U.P. by Tuesday morning and into the lower Great Lakes by Tuesday evening. Along and ahead of the cold front rain showers are expected to develop and slide across the area Monday night into Tuesday. There could be some isolated thunderstorms Monday night as the front slides through, but instability does not look overly impressive at this point. As the cold front sags southeast of the U.P. Tuesday night, high pressure and drier air will begin to filter into the U.P. allowing for decreasing clouds and an end to the precipitation. The clearing skies, calm winds and PWATs dropping to around 50 percent of normal overnight will make ideal conditions for maximum radiational cooling. This should allow temperatures to fall into the 30s over the inland west portions of the U.P. The eastern U.P. will be on the eastern fringes of the ridge so winds may be strong enough and moisture will be high enough to keep that area a bit warmer. Patchy frost may be possible over the inland west, late Tuesday night. There is a possibility that some lake effect cloud cover/light rain showers may linger a little longer into the evening, which may keep temperatures from getting as low as some of the coldest guidance. Either way, it still looks like its going to be a chilly night. Wednesday through Thursday: High pressure will be in place through this time period keeping dry air in place along with fairly light winds. Wednesday night will be another cool night, with the coolest readings expected across the eastern U.P., closer to the high pressure center. Thursday through Friday will see continued Fall- like weather with a gradual warming trend as winds turn southerly on the western side of the surface high pressure ridge. Rest of the extended: Models are trending toward increased moisture flowing into the area with increased cloud cover. A low pressure system and associated cold front are expected to approach or slide through the area Friday into Saturday; however, significant timing and intensity differences are noted in the model comparisons. With that in mind will stick with a consensus of the models at this point. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 133 PM EDT SAT SEP 10 2016 Some low clds will persist over the TAF sites thru early afternoon under a relatively moist NNW flow and sct shra behind a passing cold fnt. Expect mvfr cigs to improve to vfr later this afternoon as gusty NNW winds draw drier air into the area. As hi pres slowly blds toward the area tngt, the winds wl diminish and VFR wx wl persist into Sunday. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 406 PM EDT SAT SEP 10 2016 As a low pres moves ne of Lake Superior this evening, expect NNW winds on its backside to persist to 30 kts over much of the E half of the lake. There could still be some gale force gusts over the eastern portion of the lake into the evening before the low pres moves farther away and an approaching hi pres ridge cause the winds to diminish tonight into Sun. As the hi pres shifts to the E and a tighter pres gradient develops again on Sun night into Mon ahead of an approaching cold front, expect SSW winds to increase up to 30 kts. Winds will shift back to the NNE Mon night into Tue following the cold frontal passage, but these winds are not expected to be higher than 20 kts. Winds will diminish and back to the W as trailing hi pres moves thru the Western Lakes on Wed. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ005- 006. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...KEC AVIATION...Voss MARINE...Voss
Area Forecast Discussion
National Weather Service Phoenix AZ
242 PM MST SAT SEP 10 2016 .UPDATE...Aviation and Fire Weather Discussions... && .SYNOPSIS... Low pressure off the California coast is expected to pull monsoon moisture back northward into central and eastern AZ through Monday. This will allow the development of isolated- scattered showers and thunderstorms across south-central AZ each day. A turn to more westerly flow aloft will then push much drier air back into the desert southwest from Tuesday onward into the end of next week, with dry conditions and mostly clear skies returning back to the region. && .DISCUSSION... Latest satellite imagery shows CU developing along the Mogollon Rim and the higher terrain of southeastern AZ. Meanwhile, water vapor imagery shows drier air being transported north and eastward across southeastern CA ahead of a closed low off the southern CA coast. Cooler temperatures aloft associated with the low extend eastward into northern AZ. Further west, surface dewpoints have dropped into the upper 30s across the southwest deserts while temperatures are approaching 110 degrees in the Imperial Valley. Latest CAMs including the HRRR depict isolated convection across the higher terrain of southern Gila County late this afternoon. However, CAPE is generally lacking while CIN is predominant, associated with the relatively dry boundary layer. PoPs for this afternoon and evening remain near 10-15 percent across these areas. Conditions will become more favorable for shower and thunderstorm activity Sunday and Monday, particularly across eastern Arizona as the aforementioned closed low opens up and migrates east through the Mojave Desert. Latest operational and ensemble guidance (including the SREF and GEFS) shows an increase in uncertainty with regard to the magnitude of the overall moisture, however model consensus indicates that scattered thunderstorms will develop across eastern Pinal and southern Maricopa County Sunday afternoon. Deep-layer shear also increases, suggesting some modest organization to the cells. Setup will be similar for Monday with scattered strong storms again mostly likely across southeastern Arizona, extending back through Pinal and southern Gila counties. Sharper theta-E gradient and forcing for ascent ahead of the approaching trough also suggests an earlier onset to the convection. && .PREVIOUS DISCUSSION... Tuesday through Friday... A drying trend is expected during this period as another, stronger upper low that will be dropping southward over northern CA helps to kick out the afomentioned upper low/trof to our east, and turn the flow aloft more westerly over the region. This should end the threat for convective activity over the region as much drier air is pulled in from the west, with PWATs falling aob 0.50 inch by Thursday. High temperatures are expected to hold at near, or slightly below normal levels through this period, with highs near or slightly below 100 across the lower deserts. Lows will likely end up below normal, as the very dry airmass allows for very efficient radiational cooling each night, with lows in the 60s possible at many of the normally cooler locations. .AVIATION... South-Central Arizona Including KPHX, KIWA, and KSDL: Light surface winds with diurnal patters will continue. Some storm development will likely continue over the higher terrain to the northeast of Phoenix until 01Z but at this time are not expected to be strong enough to generate any outflows that would impact the aviation terminals today. Southeast California/Southwest Arizona including KIPL and KBLH: Light southwesterly winds over the area will turn to light and variable after 01Z. Only a few clouds are expected for the rest of the day. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Tuesday through Saturday... A return of Monsoon moisture across Arizona will continue through the early week period, allowing for scattered thunderstorm development over the mountains with slight chances for storms to last or develop over the lower AZ desert elevations. Expansion of moisture across the area will be held mostly east of the Colorado River Valley across AZ as dry air off the Pacific is brought into southeast CA. Minimum humidities will range from driest in the western district 10-15 percent improving towards the east with 20-35 percent into the Gila County mountains. Overnight recoveries will range from good to excellent. A turn to more westerly flow during the Tuesday- Friday period will begin to push the moisture/storms back to the east into extreme eastern AZ/NM. Minimum humidities will drop to the 10 to 15 percent range from by Friday, with good to excellent overnight recoveries. Outside of any thunderstorms, winds will remain mainly on the light side with some afternoon gustiness up to 15 to 20 mph area- wide on Monday and Tuesday with the strongest gusts along and west of the Colorado River. && .SPOTTER INFORMATION STATEMENT... Spotters activation is not expected this weekend. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...Hirsch PREVIOUS DISCUSSION...Percha AVIATION...Waters FIRE WEATHER...Waters
Area Forecast Discussion
National Weather Service Shreveport LA
405 PM CDT SAT SEP 10 2016 .DISCUSSION... Sct convection is just now beginning to fire over Union County AR SW into portions of extreme NW LA and adjacent E TX...along the weak cold front and line of agitated cu over these areas. The air mass ahead of the front has become moderately unstable...indicative of MLCapes of 2000-2500 j/kg. The latest run of the HRRR continues to suggest this convection continuing to expand through early evening across the warm sector as the front slowly slips SE into Ncntrl LA/lower Toledo Bend Country...before diminishing with the loss of heating/instability. Have raised pops to low chance this evening for the aforementioned areas...reducing pops to slight chance after 06Z for the Srn/Ern zones as the front sags S. The short term progs are now depicting even cooler temps than earlier runs tonight through Sunday night...with temps falling into the upper 50s late over McCurtain County OK and adjacent sections of Wrn AR. Can/t argue with this given that current dewpoints have fallen off into the upper 40s to near 50 across Ern OK...with the clearing line just NW of these areas attm. The progs are also suggesting the front pushing farther S than earlier indicated...into Srn LA to the SE TX coast Sunday...although the drier air will lag the front a ways to the N over Cntrl LA/lower Toledo Bend Country. In addition...upper ridging will begin to build E across the Srn Plains Sunday before expanding across the Ark-La-Tex Sunday night and Monday. Thus...any isolated convection Sunday should be concentrated farther S mainly across the Srn counties and parishes...and have trimmed pops down to slight chance for these areas...with any isolated convection diminishing by sunset. Sfc ridging will persist over the region Sunday night resulting in cooler temps filtering over more of the region. This will be short-lived though as the air mass will begin to gradually modify Monday as the sfc bndry to our S will begin to wash out...and bndry lyr moisture begins to return NNW. Upper ridging will persist over the region Tuesday and Wednesday...with any isolated convection confined mainly across the Srn zones where the ridge will be weakest. The ridge should begin to drift E of the MS Valley by Thursday...with shortwave troughing developing across the Srn Plains ahead of the next Cntrl Plains trough/attendent SW flow developing. Thus...convection should become more sct over E TX/SE OK Thursday before expanding areawide by week/s end. Have adjusted pops to mid-chance to match for now...with needed rain and slightly cooler temps possible as much of the region is going on in excess of 2 weeks with little to no rain and abnormally warm temps. Prelims to follow below... 15 && .PREV DISCUSSION... /issued 123 PM CDT SAT SEP 10 2016/ AVIATION... For the ArkLaTex, MVFR deck encroaching from NW in the wake of TSTM outflow overnight has the cold front filtering down under this deck from KTYR to KTXK. Pretty good cu field and heating going for much of area with tempo groups for convection timed with rapid refresh as the boundary slides SE this cycle. Any real chance for a brief shower will come to end perhaps with sunset as Northerly winds filter down overnight. Aloft KSHV VAD is showing W/NW flow 5-15KTS for climb out. All winds bcmg NE for Sun. /24/ && .PRELIMINARY POINT TEMPS/POPS... SHV 68 88 66 92 / 10 0 0 0 MLU 69 86 65 91 / 30 10 0 10 DEQ 57 85 57 88 / 0 0 0 0 TXK 63 86 60 89 / 10 0 0 0 ELD 64 84 59 89 / 20 0 0 0 TYR 66 88 66 91 / 10 0 0 0 GGG 66 88 66 91 / 10 0 0 0 LFK 71 90 70 92 / 20 10 10 10 && .SHV Watches/Warnings/Advisories... AR...None. LA...None. OK...None. TX...None. && $$ 15