Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/10/18

Area Forecast Discussion
National Weather Service La Crosse WI
557 PM CDT Tue Oct 9 2018 .SHORT TERM...(This evening through Wednesday night) Issued at 210 PM CDT Tue Oct 9 2018 Water vapor satellite this afternoon shows the trough over the Rockies deepening with an upper level low forming over southern Colorado. The low will continue to deepen and become closed over the Dakotas tonight and remained closed as it moves northeast across Minnesota Wednesday. As the low moves northeast, a strong short wave trough will move over the region and is expected to produce strong pv advection in the 500-300 mb layer as moves across late tonight into Wednesday morning. The surface front currently extends from southwest Iowa into northern Wisconsin and will not move much tonight and then get pushed east of the area Wednesday. The short wave trough will push a surface low along the front that is expected to move across the area overnight and Wednesday morning. As these features approach the area, the low level jet will crank up ahead of the surface low and should be focused on the area this evening before becoming focused farther to the north overnight. As the nose of the low level jet works into the area, should see showers and some storms rapidly redevelop over the area late this afternoon into the evening. The latest set of hi-res meso scale models then suggest there could be a break from the late evening into the early overnight until the surface low and short wave start influencing the area with more activity expected to form along the front and then work east through the late overnight into Wednesday morning. All the activity should then taper off from southwest to northeast late Wednesday afternoon through the evening with just some lingering precipitation chances into Wednesday night across the far north in the cyclonic rap around flow. With the front bisecting the area this afternoon, the areas east of it are warming up with temperatures well into the 70s. Dew points in the warm sector are in the middle to upper 60s yielding ML CAPE values of 500-1000 J/Kg over northeast Iowa into southwest Wisconsin. The 09.17Z RAP holds this CAPE in place in the warm sector through the evening with just a slight decrease expected from the loss of daytime heating. Plenty of shear will be in place with 30 to 40 knots in the 0-3 km layer and up to 30 knots in the 0-1 km layer. This continues to suggest a severe potential through the evening hours with damaging winds the main threat. There will also be a tornado threat if any storms can remain discrete and latch onto a boundary to maximize the turning in the low level wind field. .LONG TERM...(Wednesday night through Tuesday) Issued at 210 PM CDT Tue Oct 9 2018 Once this system moves past the area, much cooler air will spill in behind it. The entire area looks to have low temperatures below freezing Thursday night and headlines will be needed to highlight the end of the growing season. The next chance of precipitation will be from Saturday night into Monday as the western long wave trough finally looks like it will become progressive and should be moving east across the central part of the country. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 557 PM CDT Tue Oct 9 2018 Messy and poor aviation weather with wave and associated surface low moving through region next 24 hours. Conditions vary from VFR in warm sector, to LIFR near and just northeast of surface bounary. As this low tracks northeast, these split conditions will pretty much stay as is with our area straddling these conditions. TAF sites will stay IFR to LIFR just on north side of front with occasional convection moving through. As system pulls east tomorrow, have introduced wind shifts and should begin to see some drier air moving in with gradual shift back to MVFR conditions at least late in forecast. && .HYDROLOGY... Issued at 210 PM CDT Tue Oct 9 2018 No changes will be made to the ongoing flood watch. Conditions remain favorable for more heavy rain through the overnight. As mentioned above, the low level moisture transport will strengthen and become focused on the area this evening before focusing farther north overnight. Precipitable water values in the warm sector will remain in the 1.75 to 2 inch range with warm cloud depths around 3.5 km. With the repeated rounds of showers and storms tonight into Wednesday morning, another 1 to 2 inches can be expected to fall on grounds that are already saturated. Rivers and streams will continue to rise with numerous river flood warnings already issued and more expected to be issued tonight and Wednesday. See the latest river flood warnings and statements for specific river information or consult our hydrology web page at && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Flood Watch through Wednesday morning for WIZ017-029-032>034- 041>044-053>055-061. MN...Flood Watch through Wednesday morning for MNZ079-086>088-094>096. IA...Flood Watch through Wednesday morning for IAZ008>011-018-019-029- 030. && $$ SHORT TERM...04 LONG TERM...04 AVIATION...Shea HYDROLOGY...04
Area Forecast Discussion
National Weather Service Charleston SC
933 PM EDT Tue Oct 9 2018 .SYNOPSIS... Hurricane Michael will move north across the Gulf of Mexico before making landfall along the Florida Panhandle Wednesday. Michael will then weaken to a tropical storm as it moves northeast across Georgia and South Carolina Wednesday night into Thursday. Cooler high pressure will then build in through early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... The band of light to moderate rains has finally made it into the Charleston metro area, with it`s westward extent into areas of Dorchester to Jenkins, and it`s southern extent to near the Savannah River. Further south across the bulk of Georgia, the rain is more scattered. We have adjusted PoP based on radar trends, and since we lapse rates are poor and there is only minimal instability, we have removed mention of thunder prior to midnight. We remain on track for possible record high minimums at all 3 Climate sites. Since we are just past high tide, given the ongoing rains in downtown Charleston could certainly complicate the flooding situation. Previous discussion... A single wide band of moderate to locally heavy rainfall has setup from Metter and Millen east to Beaufort. Vsbys have been as low as 1/4 mile in the heavy rain. Could see a quick 1-2 inches of rain with this band as it moves slowly north, likely reaching the Charleston Metro area by 10 PM or so. Adjusted near term pops to reflect 100% pops for in the Millen-Charleston- Savannah-Metter corridor. While low, there is a non-zero tornado risk along the Georgia and far southern South Carolina coast. GOES-E visible imagery shows a ribbon of tropical moisture arcing from Southeast Georgia to offshore of the eastern Bahamas into the central Caribbean Sea. RAP and satellite derived data suggest PWATS of 2.25-2.50 inches are embedded in this tropical connection and is helping to support several large bands of heavy rainfall from southern Georgia and offshore of the Florida east coast. The band will slowly propagate north through the night as Hurricane Michael moves north across the eastern Gulf of Mexico and several mid-level perturbations embedded in the southeast-northwest oriented flow between subtropical high pressure moving farther offshore of the North Carolina Outer Banks of Hurricane Michael cross the area. Southeasterly low-level jetting as high as 35-40 kt will remain in lace through much of the night so any shower activity will have the potential of producing localized wind gusts of 40-50 mph. Otherwise, breezy conditions will continue at the beaches. Overnight pops will range from 70-100% along with a "rain heavy at times" qualifier. The risk for any freshwater flooding will be highest across the coastal counties, especially during the evening high tide. Widespread flash flooding is not expected through sunrise, thus a Flash Flood Watch will not be issued for this time period. It will be a warm and humid night for early October with lows ranging from the mid 70s inland to around 80 at the beaches. The record high minimum temperatures at all three climate sites could be challenged. See the climate section below for additional information on the records. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... On Wednesday the main feature will be the weak inverted trough off to the northeast of Hurricane Michael. The center of this trough will be along the SC/GA coastline at daybreak Wednesday, then move north-northeast through early afternoon. We expect numerous heavy showers with isolated tstms across the area during the morning with the greatest coverage and intensity over southern SC closer to the trough. Unseasonably high PWATs in excess of 2.1" will support torrential rainfall at times. During the afternoon the best convergence associated with the trough are is forecast to move north of the area though we then expect some outer rain bands from Michael to start rotating through the area. A bit of a lull is possible Wednesday evening, then the rain shield associated with Michael is expected to move into interior southeast GA with some outer bands farther to the north and east. The brunt of the torrential rainfall associated with Michael`s circulation will move through on Thursday with the greatest effects over our inland zones. Latest storm total QPF shows 2-4 inches across coastal sections and 3-5" inland. The strongest winds will begin in southeast GA late Wed night and affect most of southern SC during the day Thursday. An enhanced tornado threat appears likely from Wednesday afternoon through at least Thursday morning based on model progs for low-level helicity and surface-based instability. Slightly cooler and drier weather expected late Thursday night into Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Late this week, surface high pressure will build back into the region behind departing TC Michael. Precipitation potential is looking rather low Friday and Saturday as a dry column sits overhead, then rain chances will increase with increasing moisture levels ahead of an approaching cold front Sunday into the first part of next week. Temperatures look to remain above normal. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... A band of moderate to heavy rain will move north into the KCHS terminal by late evening and persist through about 07z. Expect vsbys as low as 1/2 mile at times with this line, but vsbys should generally average 2-3SM. Other banks are likely to develop overnight and impact both KCHS and KSAV. High resolution guidance supports such a line reaching KSAV 07z and lingering through about 10z. Again, prevailing vsbys should be MVFR and as low as 2SM at times. Rain should move out the terminals by 10z and expect mainly dry conditions to prevail for the remainder of the 00z TAF period. Steadier rains associated with Michael should hold off until after 00z, although it will be close at KSAV. Gusty winds will persist through the night and increase a bit Wednesday afternoon. Extended Aviation Outlook: MVFR or lower conditions likely at both terminals Wednesday afternoon through Thursday night as Hurricane Michael moves west of the area. The greatest chance for IFR ceilings and/or vsbys will be late Wednesday night through Thursday afternoon due to moderate to heavy rain. && .MARINE... Tonight: Nasty marine conditions will continue across all waters tonight with winds 20-25 kt with gusts to 30 kt. Shower activity will be capable of producing localized wind gusts to 40-45 kt. Seas will build through the night, reaching 5-8 ft nearshore waters and 9-11 ft offshore waters. Wednesday through Saturday: The impacts of Hurricane Michael are obviously the main concern with this package. Marine conditions will become increasingly treacherous during the day Wednesday with the strongest winds and largest seas Wednesday night into Thursday. Improving conditions Thursday night into the weekend as high pressure builds in. Rip Currents: A high risk for rip currents continues into Wednesday due to persistent, strong onshore wind, some swell and astronomical influences. The rip current risk will remain elevated through the week. && .TIDES/COASTAL FLOODING... Coastal Flooding: The decision was made locally to issue a long-duration Coastal Flood Advisory for all coastal zones, excluding Tidal Berkeley, to cover all high tides through the duration of Michael. Minor to locally moderate coastal flooding is expected through the period. At this time, levels are not expected to reach Coastal Flood Warning criteria for either Fort Pulaski or Charleston Harbor with average inundations above ground level expected to stay 2 feet or less. This will be watched carefully and warnings will be issued if needed. High Surf: Expect breakers of 5 to 8 feet to impact the surf zone before winds turn offshore in the wake of Michael. A High Surf Advisory has been posted for all beaches. && .CLIMATE... Record high minimums for 9 October: KCXM: 77/2017. Record high minimums for 10 October: KCHS: 75/2017. KCXM: 78/2017 and previous. KSAV: 75/2017. Rainfall record for 10 October: KCHS: 1.82/1990. KCXM: 2.13/1990. KSAV: 5.68/1990. Rainfall record for 11 October: KCHS: 4.48/1990. KCXM: 5.46/1990. KSAV: 4.43/1885. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...Tropical Storm Warning for GAZ087-088-099>101-114>119-137>141. High Rip Current Risk through Wednesday evening for GAZ117-119- 139-141. High Surf Advisory until 8 PM EDT Thursday for GAZ117-119-139- 141. Coastal Flood Advisory until 2 PM EDT Thursday for GAZ117-119- 139-141. SC...Tropical Storm Warning for SCZ040-042>045-047>052. High Rip Current Risk through Wednesday evening for SCZ048>051. High Surf Advisory until 8 PM EDT Thursday for SCZ048>051. Coastal Flood Advisory until 2 PM EDT Thursday for SCZ048>051. MARINE...Tropical Storm Warning for AMZ330-350-352-354-374. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE... TIDES/COASTAL FLOODING... CLIMATE...
Area Forecast Discussion
National Weather Service State College PA
1054 PM EDT Tue Oct 9 2018 .SYNOPSIS... A strong ridge of high pressure will remain parked off the Mid Atlantic coast through Wednesday. A cold front will move through the area Thursday. Hurricane Michael is expected to hit the Florida Panhandle tomorrow and then turn sharply northeastward on a track off the east coast south of Pennsylvania. Cooler and drier conditions will arrive for Friday and the upcoming weekend. && .NEAR TERM /UNTIL 8 AM WEDNESDAY MORNING/... Evening GOES-16 IR FOG product (10.3-3.9um) shows a fair amounts of cirrus spreading NE across the region with several areas of shallow stratocu clouds across our far eastern zones, where mean sfc-925 mb streamlines were advecting moisture with u60s to l70S DEWPOINTS off the Western Atlantic and Chesapeake Bay. lATEST 09/23z RAP LLVL RH fields shows stratocu deck lowering into a stratus deck and spreading north-northwest across our the region to blanket most of the CW outside of portions of Mckean and Warren counties, and Cambria/Somerset counties west of Laurel Ridge. With the return of the low clouds overnight, we could see some patchy drizzle develop over eastern sections, but no real measurable precipitation is expected at this time. The clouds and light southerly flow at the sfc will create another muggy night. Lows in the 60s will average around 20 deg above normal. Some maxi min records in the upper 50s to mid 60s are on target to be broken. The record warm low at KBFD of 57F looks to be the most susceptible to be broken, considering the current dewpoint of 64F there, and a fcst min of only 61F. && .SHORT TERM /8 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Wednesday looks like it will be very similar to the last several days. Morning clouds and patchy fog burning off to a partly sunny afternoon. Highs once again will range from the mid 70s to the lower 80s. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... *Heavy downpours and localized flooding possible Thursday *Significant cool-down expected by Friday as a more typical fall weather pattern finally takes hold into next week Periods of locally heavy rain are likely on Thursday as a cold front crosses the Appalachians and interacts with tropical moisture from Michael. PW values are forecast to reach 1.5 to 2.0 inches which is well-above normal for early/mid October. Blend of NBM/WPC QPF yields 1-2 inches over the southeastern 1/3 of the CWA falling mainly in the 12-hr window ending 00Z Friday. Very soggy soils and swollen streams from relentless rainfall over the last several months will make this area susceptible to potential flooding concerns. The WPC D3 excessive rainfall outlook (ERO) places southeast PA in a marginal risk. The models are in general agreement in keeping the heaviest rains directly associated with Michael from the NC piedmont across southeast VA to the Delmarva Peninsula Thursday night into Friday. There is some uncertainty in the max QPF location and timing with at least some risk that it could track or shift farther north, but for now the most likely outcome is a southern track with the main impacts staying south/east of central PA. A significant pattern change is expected to follow in the wake of Michael as it accelerates away from the southern Mid Atlantic coast on Friday. The extended summer pattern will come to an end with all signs pointing toward noticeably cooler, more typical fall weather lasting into next week. After one of the warmest starts to October on record, the upcoming period of seasonably cooler weather with near to below average temperatures will feel rather chilly this weekend and next week. Parts of the northwest Alleghenies may see frost Sunday morning. Sub-zero air at 850mb crossing the lower lakes should result in rain showers (perhaps the seasons first flakes?) over the NW Allegheny Plateau and Fri-Sat. Model consensus shows the next rain-maker impacting the area early next week. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... VFR areawide this evening under influence of high pressure (centered off to our east). Expect to see a return of low clouds and areas of patchy fog overnight in anomolously high dewpoint air and southerly flow, with much of central PA becoming MVFR then IFR for several hours centered around sunrise. Could see development of some dense fog over the Susq Valley around this time as well. Restrictions expected to last through mid morning Wednesday. As like the past several days, conditions will improve by Wednesday PM. .Outlook... Thu...MVFR-IFR cigs/LLWS early becoming MVFR/VFR. Showers/isolated T-storms accompanying a cold front. Post- frontal low cigs developing northwest mtns Thursday night-Friday morning. Fri...MVFR cigs possible NW. Wind gusts 20-25kts from NW. Sat...MVFR cigs possible NW. Sun...No Sig Wx. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...La Corte LONG TERM...Steinbugl AVIATION...RXR
Area Forecast Discussion
National Weather Service Cheyenne WY
557 PM MDT Tue Oct 9 2018 .SHORT TERM...(Tonight - Wednesday) Issued at 304 PM MDT Tue Oct 9 2018 A broad swath of snow has developed across much of western/central Nebraska this afternoon. The western extent of this activity as of 21z was approximately along and south east of a line from Kimball- Alliance. This activity is associated w/ an impressive TROWAL that has taken shape on the back side of a strong upper-level shortwave currently lifting into the Central Plains, along with an excellent fetch of moisture contributing to deep saturated profiles. QPF via several high-resolution models including the HRRR & HREF continues to suggest the potential for snowfall accumulations in excess of 3 inches, potentially as high as 6 inches although snowfall rates do not appear high enough to overcome warm ground temperatures. Rates have been increasing over the last few hours though, w/ visibility finally falling below 1 SM at Sidney recently. We would anticipate seeing some accumulations shortly, especially on grass or elevated surfaces. Winter Wx Advisory looks to be in good shape through the midnight hour, although later shifts may consider extending if any road issues linger into the night. Accumulating snow should end by 06z or so as sounding profiles quickly dry out. A second disturbance was observed over the Intermountain West this afternoon per GOES-16 Water Vapor imagery. This system will follow very quickly in the footsteps of the ongoing weather maker, likely resulting in snow across much of Carbon County by 09-12z. Mountain areas may receive 6 to 12 inches, while lower elevation areas will have a good chance to see a general 2-4 inches of snow through Wed afternoon. The system will be weakening, so just how far east snow accumulations will extend is uncertain at this time. It`s possible the I-80 summit may be impacted as well though. The Laramie Valley will likely be shadowed by low-lvl easterly flow regardless, so do not expect to see much in the way of snowfall there. We went ahead and issued a Winter Wx Advisory for far western areas for the time being, and later shifts can expand eastward if necessary. .LONG TERM...(Wednesday Night - Tuesday) Issued at 304 PM MDT Tue Oct 9 2018 Warmer and mostly dry conditions prevail moving into the end of the week as a southerly flow affects the region. However, by Saturday night, the next strong system looks as though it will drop out of the north, bringing the next round of cold temperatures to the region and the next shot at decent precipitation. For now, the remnants of Hurricane Sergio look like they will stay south and east of the region, but should the moisture track change and push further north, this system may spell another story for the region. This will need to be monitored as we move towards the end of the week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 551 PM MDT Tue Oct 9 2018 Band of light to moderate snow over the Nebraska Panhandle will continue moving to the east northeast over the next few hours. This should keep MVFR to IFR conditions in play for SNY and AIA through later this evening. Low ceilings will remain in place dropping further overnight as upslope flow continues overnight. Expect LIFR in some spots as additional snow showers develop over the high terrain to the west and spread east. Light to moderate snow will continue tomorrow bringing reduced visibilities to many southeastern Wyoming and Western Nebraska Terminals. Aviators use cation and stay updated on weather conditions through out the area as snow and icing could impact safety. && .FIRE WEATHER... Issued at 242 AM MDT Tue Oct 9 2018 A cold and active pattern will continue over the next week, significantly limiting fire weather concerns and aiding in fire containment issues. The next best chance of measurable precipitation across the mountains will arrive Wednesday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory from midnight tonight to 6 PM MDT Wednesday for WYZ109>114. NE...Winter Weather Advisory until midnight MDT tonight for NEZ021- 055. && $$ SHORT TERM...CLH LONG TERM...AB AVIATION...AL FIRE WEATHER...AB
Area Forecast Discussion
National Weather Service Dodge City KS
712 PM CDT Tue Oct 9 2018 ...updated aviation section... .SHORT TERM...(This evening through Wednesday) Issued at 123 PM CDT Tue Oct 9 2018 The synoptic trof that has brought days of rains with significant rainfall has finally started to move out of the region. Rain and clouds will exit the FA through this evening from the south to the north. A ridge of high pressure will build in its wake. There will be weak cold air advection associated with this. Do have a freeze warning for 4 counties across the NW. Main fly in the ointment for this is cloud cover. Models do show partial clear and with weak CAA in place, temperatures could get near freezing. The area that is in the freeze warning is just climo for their first freeze and along low lying areas such as near the Ark river basin. Otherwise, lows to the east should be warmer with additional/lingering cloud cover. For Wednesday, high pressure will be in control and the area should dry out. Highs should be mainly in the 50s. .LONG TERM...(Wednesday night through Tuesday) Issued at 123 PM CDT Tue Oct 9 2018 Will have to watch for the freezing potential for Thursday morning. High pressure is just to our north and winds are weaker. In addition, not much in the way of clouds are expected through the overnight period. A large area of the NW and N zones may get close to freezing. Will defer a headline for now as we have hydro concerns and freezing concerns already during the short term period. The GFS and EC disagree with the slight chance of showers on Thursday. A better chance at precip is still indicated by long range models next weekend. Here the synoptic wave driving the weather is strong than compared to the Thursday system. In addition, there is more in the way of boundary layer moisture as well. The EC does have cold enough 850-hPa temperatures for some mixed precipitation and even snow on Sunday. Confidence in the thermal fields is low at this point. The EC is still advertising cold air moving in the wake of the system and a freeze or even a hard freeze may be possible Monday morning for much of the FA. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 642 PM CDT Tue Oct 9 2018 Marginal ceiling improvement is forecast by the HRRR over the next few hours, generally through mid evening - however little improvement over that will be seen until well after midnight. Therefore we can expect the IFR category ceilings through around 03 UTC with rain showers dwindling as the Missouri Valley surface low lifts northeast and MVFR category ceilings. An intrusion of drier air aided by downslope will lead to removal of the widespread stratus during the overnight with some scattered 1500-3000 ft clouds lingering mainly in the HYS area by 12 UTC. && .PRELIMINARY POINT TEMPS/POPS... DDC 35 55 35 53 / 10 0 10 0 GCK 34 53 33 50 / 20 0 10 10 EHA 33 56 35 55 / 20 0 10 20 LBL 34 56 34 54 / 10 0 10 10 HYS 36 52 31 50 / 40 0 0 0 P28 41 58 40 57 / 10 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 2 AM CDT /1 AM MDT/ to 10 AM CDT /9 AM MDT/ Wednesday for KSZ043-061-062-074. Frost Advisory from 2 AM to 10 AM CDT Wednesday for KSZ044-063- 075>077-084>087. && $$ SHORT TERM...Sugden LONG TERM...Sugden AVIATION...Russell
Area Forecast Discussion
National Weather Service Grand Forks ND
1008 PM CDT Tue Oct 9 2018 .UPDATE... Issued at 1004 PM CDT Tue Oct 9 2018 No big changes needed. Updating grids to show advance north of the rain area. Just arrived in Fargo between 2-3z and timing would bring it to Grand Forks 07z or so. HRRR cools 925 mb layer to snow levels 09z-12z period. Incoming NAM shows about the same ideas as past runs with snow band near mid level def zone with higher rates of snow in NW MN later Wed into Wed eve vs more Wed morning-midday in Jamestown/Valley City area. UPDATE Issued at 630 PM CDT Tue Oct 9 2018 Rain area on its way northward and updated timing of rain arrival as it spreads north. Timing of rain to snow changeover is the main fcst issue with the idea of it doing so in the 09z-13z period across the area for most. Snow amounts of 3-6 inches look good for the advisory area...though as usual some slight differences in exact heavy snow placement. NAM and RAP are more JMS-GFK-ROX vs GFS seems to target more FAR-TVF-BDE. && .SHORT TERM...(This evening through Wednesday) Issued at 300 PM CDT Tue Oct 9 2018 Snow totals and winter headlines will be the main headaches for the period. Water vapor loop shows the main upper trough over CO/NM, with a kicker system digging down through OR/ID that will help push the more southeasterly trough into the Northern Plains by Wednesday afternoon. The surface low is still well to our south over KS, but will move quickly northeastward tonight into IA/southern MN and then into the Great Lake for tomorrow. There will be plenty of synoptic lift from the trough as it lifts into our area, and the models continue to indicate strong 700mb frontogenesis setting up over our area tonight into tomorrow. Rain currently moving through eastern SD will enter our southern counties this evening, pushing northward throughout the night. The main deformation band will continue over the central CWA for much of the day tomorrow, before weakening and pushing eastward during the late afternoon and evening. The biggest question is not if we will get rain and snow, which is yes, but how much snow will accumulate and what the impacts will be. GEFS plumes are still all over the place with snow amounts, ranging from less than an inch of accumulation to near 10 inches at KBDE. There will be a decent amount of cold air coming down the backside of the low pressure system, along with strong northwest winds. However, quite a bit of the QPF will be falling during the daytime hours, and there should be at least some melting as snow falls. With the melting and compaction of wet snow, think that even with 0.5 to 1.5 inch of QPF there will be a pretty broad area of 3 to 6 inches. The exception of this will be where any mesoscale banding sets up, the exact location still unknown. Could see more than 6 inches to even warning level snow amounts in that band, but again, do not know the exact location at this point. Thus, will put out a broad winter weather advisory, and highlight in the wording there will be a narrow band of heavier snow. Visibilities will also be reduced within that narrow band, although with the wet snow it will be more splattering on north facing surfaces vs blowing. .LONG TERM...(Wednesday night through Tuesday) Issued at 300 PM CDT Tue Oct 9 2018 Potent storm affecting the forecast area on Wed will see snow gradually taper off from southwest to northeast during Wed night into Thu morning, ending over north central MN by early Thu morning. Cool and breezy, but drier weather will move back into the region for Thu as temperatures remain solidly in the 30s. Zonal flow and modest warm air advection will result in some warming into the 40s on Sat as a clipper system moving out of Canada brings rain and snow chances to northeast ND and northwest MN. Overall winter weather impacts are expected to be minimal at this time. Any residual pcpn will move east during Sun with temps dipping well below average once again. Another clipper offering chances for mixed pcpn is scheduled for Tue with some hope for moderation in temps maybe to near normal by the end of next week or next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 630 PM CDT Tue Oct 9 2018 Conditions will go downhill thru the night with majorty of the areas in IFR conditions for vsby and ceilings. North winds will increase to 15 to 30 kts highest in the RRV. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Weather Advisory until 1 AM CDT Thursday for NDZ008-016- 024-026>030-038-039-049-052>054. MN...Winter Weather Advisory until 1 AM CDT Thursday for MNZ001>009- 013>017-022-023-027-028. && $$ UPDATE...Riddle SHORT TERM...JR LONG TERM...WJB AVIATION...Riddle
Area Forecast Discussion
National Weather Service North Platte NE
629 PM CDT Tue Oct 9 2018 .SHORT TERM...(This evening through Wednesday) Issued at 333 PM CDT Tue Oct 9 2018 The models continue to track a closed h700mb low northward through ncntl Nebraska tonight. Last night`s heavy snow discussion from WPC indicated the low was closing off faster than previously forecast by the models. This faster intensification process would likely cause snow to develop farther south and indeed, snow is underway this afternoon across southwest Nebraska and northeast Colorado. In fact, cameras throughout ncntl Nebraska have shown a mix of rain and snow this afternoon. Boundary layer heating is holding up the changeover process to all snow. As sunset approaches this evening, the heating process will cease and a rapid changeover should occur, especially across western Nebraska where winds will become northwest. The forecast snowfall amounts, up to 7 or so inches, uses an aggressive approach which is appropriate for the strength of the upper level disturbance. The forecast uses a blend of the HRRR, RAP and HREF models as a basis for snowfall. The forecast places the area along and west of a line from Hayes Center to Newport in a winter weather advisory. A winter storm warning is in place for Cherry county. The snow should become moderate to heavy this evening in some areas. The models show a convectively enhanced rain-snow line setting up from roughly Hayes Center to North Platte to Ainsworth. Just west of this line, a period of heavy snow should develop with 1 inch per hour accumulations possible. The disturbance and the snow should exit ncntl Nebraska Wednesday morning. A period of light non-accumulating snow is possible across the eastern Panhandle in the afternoon associated with a disturbance following quickly on the heels of tonight`s storm. .LONG TERM...(Wednesday night through Tuesday) Issued at 333 PM CDT Tue Oct 9 2018 Rather unsettled during this period, but no major storms are expected. First will be the cold temperatures expected Wednesday night into Thursday morning. High pressure will build in during this time, and with light winds and clear skies, a widespread freeze can be expected. A strong shortwave trough will cross the area Thursday night into Friday morning as flow aloft transitions to northwesterly. Mid level frontogenesis increases Thursday evening and persists into Friday morning. Appears to be cold enough for a light rain/snow mix during this time, but little accumulation is expected. Another disturbance drops quickly southeast Saturday night into Sunday. A few showers may accompany this, but available moisture looks quite limited by this time. As the northwest flow becomes established, several cold fronts will accompany the disturbances, which will keep temperatures below normal. Sunday appears to be the coldest day, with highs only in the 30s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 628 PM CDT Tue Oct 9 2018 We continue to see widespread MVFR and lower ceilings/visibility across west central Nebraska, this trend will continue through much of the forecast period as a strong upper low lifts north into the northern plains. The precipitation will be heavy at times before ending south to north on Wednesday. Snow accumulations are possible, especially across north central Nebraska, including KVTN. AT KLBF, we will see a change over to snow later this evening, which will lower visibility. This should occur before 06z. Otherwise, northerly surface winds will prevail, with gusts in excess of 20kts for most terminals through the forecast period. At KLBF, winds will fall below 15 kts overnight. && .LBF WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 AM CDT /8 AM MDT/ Wednesday for NEZ004-006-008-009-022>026-035>037-056>059-069-070. Winter Storm Warning until 9 AM CDT /8 AM MDT/ Wednesday for NEZ005-094. && $$ SHORT TERM...CDC LONG TERM...Taylor AVIATION...Jacobs
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
721 PM CDT Tue Oct 9 2018 .SHORT TERM... 210 PM CDT Through tonight... Isolated to scattered showers and storms are expected this afternoon. The only forcing is surface heating so widespread storms are not expected. The latest RAP analysis shows up to 2000 J/kg of CAPE and 25-35 kt of shear. DCAPE values are 800 J/kg or less. While a storm or two may pulse up close to severe limits, the vast majority of storms will not be severe. Main threats will be gusty winds, heavy rain, and lightning. Convection will diminish after the sun goes down and forcing eases. I kept a chance of showers and storms west of a McHenry to LaSalle line this evening as guidance suggests a few showers or storms may percolate there ahead of the main cold front. Speaking of the cold front currently over central Iowa, it will slowly march east tonight. Showers and storms are expected ahead of it, and will mainly impact areas along and west of I-39. I have low confidence in the number of showers and storms tonight because forcing will be mainly tied to the front. A couple transient vorticity streamers may help force precipitation, but the streamers are not forecast to be very strong. Due to cloud cover tonight, low temps should be mild in the upper 60s. JEE && .LONG TERM... 252 PM CDT Wednesday through Tuesday... A pronounced pattern change will occur during the beginning of this period, with the transition time providing gusty showers/storms on Wednesday and then prevailing wind gusts 30-35 mph Wednesday night into Thursday. This will be followed by the likelihood for frost Thursday and Friday nights if winds can diminish enough. The well-defined closed upper low over southeast Colorado this afternoon will eject across the Upper Midwest tomorrow, with guidance in good agreement on a deepening surface low to just below 1000 mb near La Crosse WI by mid-afternoon. With the negative tilt to the ejecting wave, strong forcing for ascent will be overriding the deep moisture plume and pre-frontal convergence, all a recipe for widespread showers. The instability in the column becomes quite narrow, not that atypical for ahead of an autumn cold front especially one with deeper warm cloud processes such as this. But given the negative tilt to the wave, can see embedded thunderstorms being present. Lightning or not, the unidirectional strong southwest winds in the column provide the potential for downdraft-driven gusty showers. In any more well-defined arcs of convective activity, mainly any that are not far ahead of the front in the afternoon, the potential for isolated severe gusts will exist. Some members of the higher-resolution guidance family try to key in on higher reflectivity/deeper updrafts moving to the east-northeast across the area in the afternoon, but others do not. While there is ample low-level shear, the orientation of the deeper shear vectors to the boundary is not ideal for discrete activity, and this pre-cold front is not an ideal setup for a tornado threat. But surface winds are backed to around due south, so if mode can be more discrete immediately ahead of the main convective line/semi-line, that may not be ruled out. After a mild and humid day with highs in the 70s, the cold front will sweep through Wednesday evening. With the strong isallobaric response and steeping low-level lapse rates in cold advection, westerly winds behind the front will sharply increase. Gusts immediately behind the front may reach 40 mph, with regular gusts of 30-35 mph expected into the day Thursday. Temperatures by daybreak Thursday look to be lower 40s. Despite a mainly sunny sky on Thursday, the northwest winds will keep highs from rebounding much, with highs generally around 50 (around 35 degrees colder than today). Surface high pressure around 1021 mb is forecast to build into the Mississippi River Valley Thursday night. It is likely that some northwest wind will be maintained through the night in our area, at least given current forecasts, though challenging to say if enough to mitigate frost. With the low starting point in temperatures going into the night, readings will likely dip to around freezing in north central Illinois and continue frost mention in the forecast. The Friday forecast became a bit more tricky, as the 12Z EC shifted north with the Pacific-hybrid system moving quickly across the region, and places that more over our area. This would bring light rain potential. Even with that forecast, the quick progression would likely favor a clear sky Friday night and a frost threat and depending on wind speeds again, possibly a freezing threat into north central Illinois. The weekend, especially the latter weekend into Monday, look unsettled in global guidance, but a wide disparity between models and between runs on how the pattern will evolve. This is increased by the fact the flow is split with a phasing potentially over/near the Great Lakes. Chances for rain have been increased within blended model guidance, but apart from that it is presently difficult to give more details in coverage/timing than that. The pattern favors cold advection undercutting the backside of precipitation, but right now the chances for some flakes of snow before ending look to be north in Wisconsin. Highs on Monday are only forecast to be in the mid 40s in the northern CWA and could end up being a little cooler than that in time. MTF && .CLIMATE... 305 PM CDT Records for today, October 9: Record High Record High Minimum ------------------------------------------ Chicago: 86 (1949) 68*(1879) Rockford: 84 (1920) 67 (1949) * With Chicago not having dropped below 70 this morning, the low for the calendar day today may remain 70 or above. This will be only the 7th time that has happened in October, and the 2nd latest after October 21, 1979. MTF && .AVIATION... For the 00Z TAFs... The main concern for the period will be timing and coverage of shra/tsra spreading across the region tomorrow. For the remainder of the evening and overnight, expect relatively quiet conditions at the terminals. Much of the sct shra/tsra moving through the area this afternoon was either diurnally driven or associated with a weak mid-level impulse. This mid-level impulse has moved north onto Wisconsin and both the diurnally driven cu and shra have dissipated with sunset. Under a moderate southerly gradient, expect that winds should remain generally southerly at 5-10 kt through much of the night. The pressure gradient is expected to strengthen late tonight as low pressure over the Upper Missouri Valley deepens while tracking newd and an associated cold front pushes east through Iowa. Expect that the potential for shra/tsra will rapidly increase through the morning hours as the cold front pushes east through the day. Much of the activity should be along and ahead of the front in an area of strong continued warm, moist advection. With instability increasing through the morning, scattered shra/tsra should develop, but the more organized, widespread convection will be more closely associated with the frontal zone. The general trend of precipitations should be in the form of rounds of showers with embedded thunder until the cold front finally pushes through the area. Latest guidance suggests that the fropa may not occur until close to 00z tomorrow evening at RFD and 02Z or so at the Chicago area terminals. So, given some uncertainty with the fropa timing, have not included the fropa details in the RFD/DPA TAFs just yet and introduced the fropa timing of 02z at ORD/MDW, though that exact timing will be subject to adjustment in later updates. && .MARINE... 305 PM CDT A strong weather system will move across the region Wednesday into Wednesday night. In response to this, south winds on Wednesday will be near Small Craft Advisory, and there could be some gusty showers and storms as well, especially in the afternoon. A strong cold front will pass Wednesday evening. Behind this there will likely be wind gusts nearing gales and potentially to frequent gales along the Illinois nearshore. This is especially true further from the immediate shore given lake-induced instability. The gusts should slowly ease after midday Thursday. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...LMZ742-LMZ743-LMZ744-LMZ745...9 PM Wednesday to 10 PM Thursday. Gale Watch...LMZ740-LMZ741...9 PM Wednesday to noon Thursday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
707 PM CDT Tue Oct 9 2018 .SHORT TERM... (Through Late Wednesday Afternoon) Issued at 336 PM CDT Tue Oct 9 2018 Main concern in the short term continues to be the strong cold front that will slide through the region late tonight through Wednesday. Latest HRRR is beginning to come into better agreement with what is actually happening over region as of 20z. Ahead of system, scattered showers and thunderstorms are developing in a moderately unstable environment with surface based CAPES in excess of 1500 J/kg and effective bulk shear 30+ kts over portions of central/northeast Missouri as of 20z. This initial round of activity is more diurnally driven so should see showers and storms diminish a bit towards sunset. However, the break in activity will not be long as more significant storms develop along prefrontal trof over central Missouri after 02z Wednesday and track east through forecast area during the late evening and early morning hours. There will be plenty of instability and shear late into the evening for a few strong to severe thunderstorms over portions of central/northeast Missouri as well as west central Illinois. SPC has kept this area in a slight risk with the main threat being damaging winds, though isolated tornadoes and large hail are possible. Then another round of activity to fire along main cold front after 08z Wednesday over western Missouri and track eastward through forecast area during the day on Wednesday. With progressive nature of system, rainfall amounts will remain below flash flood criteria, though could see between half an inch and an inch of rainfall through Wednesday afternoon before system exits region. As for temperatures, another mild night tonight with lows only in the mid to upper 60s. On Wednesday, highs will be in the upper 60s to upper 70s, with steady or falling temperatures during the afternoon hours most locations. Byrd .LONG TERM... (Wednesday Night through Next Tuesday) Issued at 336 PM CDT Tue Oct 9 2018 Strong surface ridge to build into region Wednesday night with scattered showers exiting region. Ridge will usher in much colder air with lows in the upper 30s to upper 40s Wednesday night. Highs on Thursday will only be in the low 50s to low 60s, which are 10 to 15 degrees below normal for this time of year. By Thursday night, even colder temperatures can be expected with lows in the mid 30s to low 40s. This cold air combined with little or no winds and clear skies could allow for the formation of patchy frost across northern portions of forecast area. However, confidence is low as a quick moving shortwave to approach region towards daybreak on Friday, so should see increasing clouds. Left out mention of patchy frost for now. Upper level shortwave to slide through region on Friday undercutting surface ridge. Even though moisture will be limited, isolated/ scattered showers will develop by midday and slide quickly east through forecast area, exiting by early Friday evening. Beyond that, better chances of rain will move into the region Saturday evening and persist through Sunday night before exiting Monday morning. Still some differences in timing, strength and duration of the rain for the weekend as a southern stream shortwave slides through region just south of forecast area Saturday night through Sunday morning and a northern stream system slides through region Sunday night. No major changes to ongoing forecast at this time. Below normal temperatures to persist through remainder of forecast period. Byrd && .AVIATION... (For the 00z TAFs through 00z Wednesday Evening) Issued at 646 PM CDT Tue Oct 9 2018 Low pressure over the eastern Plains will strengthen and move northeast tonight and Wednesday. This will push a cold front east through Missouri into Illinois through Wednesday afternoon. Expect waves of showers and thunderstorms ahead of the front tonight into Wednesday, with the first wave moving through central and northeast Missouri this evening. While prevailing conditions this evening and into the early overnight hours should stay VFR, any shower or thunderstorm will be capable of producing lower ceilings and visibilities in heavy rain. There will be a general lowering of ceilings and also expect an increase in coverage of showers and thunderstorms Wednesday morning as the cold front moves into central and eastern Missouri. Expect widespread MVFR ceilings and visibilities, and some IFR is also expected with the showers and storms. Some lingering MVFR ceilings and showers will likely persist behind the front Wednesday, but there should be a general improving trend after the front passes during the afternoon. Wind should shift sharply from the south to the west as the front passes. SPECIFICS FOR KSTL: Expect VFR flight conditions to prevail at Lambert through the evening and into the pre-dawn hours of Wednesday morning. Most model guidance holds the bulk of the rain back until after 10Z Wednesday morning, but I cannot totally rule out a few showers or thunderstorms before that. Expect ceilings to drop ahead of the front on Wednesday morning when most of the rain rolls in. Current thinking is prevailing low end MVFR ceilings with occasional MVFR visibilities in the heavier showers or storms. There is a possibility that ceilings could drop to IFR, but confidence is low at this time so did not go that low in the TAF. Latest model trends are pushing the front through Lambert around 18Z on Wednesday. Should see a general decrease in precipitation and rising ceilings after the front moves through. Wind will turn sharply from the south-southwest to the west when the front passes through the terminal. Carney && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 70 76 46 60 / 60 90 5 0 Quincy 66 70 41 54 / 90 90 5 0 Columbia 64 68 40 56 / 90 80 0 0 Jefferson City 67 70 42 58 / 90 80 0 0 Salem 68 79 48 59 / 40 100 20 0 Farmington 68 76 45 61 / 40 90 5 0 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Blacksburg VA
1121 PM EDT Tue Oct 9 2018 .SYNOPSIS... High pressure over the western Atlantic will begin to lose influence over the region late tonight into early Wednesday. A surge in subtropical moisture banked against the Blue Ridge will lead to a period of steady rains Wednesday. Hurricane Michael is expected to progress through the southeast US Wednesday into Thursday. Moderate to locally heavy rain in association with Michael`s closest passage is expected to begin Thursday across the southern half of the region. A cold frontal passage late Thursday evening is expected to usher in a more seasonable air mass into the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1000 PM EDT Tuesday... Latest updates remain minor, basically modest adjustments to rain chances through midnight based on the HRRR rapid update weather forecast model, as well as hourly temperatures. Overall, the afternoon forecast package remains on track. As of 205 PM EDT Tuesday... A persistent and stout anticyclone, both at surface and aloft is centered off the mid-Atlantic coast, which is extending a ridge back westward into the Appalachians. This has led to a persistent east to southeast fetch across a large part of the Appalachians and VA/NC Piedmont region. Partly to mostly cloudy skies exist across the region this afternoon and will continue to be the case at least for the first part of the evening. Widely scattered showers in this regime across northern/central NC will continue to progress westward and ascend upslope against mainly the southern Blue Ridge through mid-evening, as reflected in most finer-resolution guidance. While southeast upslope will continue, as we progress deeper into the evening, model guidance QPF becomes more nebulous and spotty but again is largely along or east of the Blue Ridge. Forecast BUFKIT RH profiles again show re-development of lower stratus with any cloud breaks filling in overnight, as was the case last night. As this moisture is quite shallow - a mostly unsaturated moisture profile above 850 mb - suspect that only drizzle or light rain would predominate again through the bulk of the overnight. Overall through overnight, rain amounts are pretty minimal and are generally a few hundreths of an inch or less, but amounts up to a tenth possible along the southern Blue Ridge from Carroll County southwest into Watauga County. Turbulent mixing from a continued southeasterly wind around 5-10 mph should keep mist from developing in most areas, though there could still be some patches at times into the Blue Ridge. Lows again on the whole similar to last night in the 60s, again quite unseasonable for this time of year. Wednesday is shaping up to be a pretty wet day, as we begin to feel the fringe effects of Hurricane Michael in the form of elevated tropical precipitable water values (GFS depicts values rising to on the order of 2"+). While still some minor timing differences exist between available 12z models, they each show a band of what is likely to be a period of moderate to locally at-times heavy rain showers progressing from south to north from around mid-morning across the NC Blue Ridge/foothills through early evening. This steady rain shield is the one currently affecting portions of northeast FL into coastal GA/SC, this rain enhanced by subtle vort energy in the weakness in the large high over the western Atlantic seaboard mentioned above. As a southeasterly low-level jet to the tune of 30-40 kts will be occurring, expect there to be some significant upslope enhancement to rainfall totals on the lee of the Blue Ridge and into the foothills with notable rain shadowing and a relative minimum in PoPs/QPF as one progresses further northwest across part of the New River Valley/Mtn Empire region into southeast WV. There`s also a small amount of CAPE to the point where I did include a few possible rumbles of thunder for areas within or close to the Blue Ridge into the Piedmont. This will only serve to enhance rainfall totals, which through Wednesday afternoon should range from about a half to three-quarters of an inch from the NC foothills, Roanoke valley area into part of Southside, to locally near an inch along the escarpment of the Blue Ridge into Ashe and Watauga Counties. Otherwise, rain amounts taper to a quarter to a third of an inch in the New River Valley to less than a quarter inch into southeast WV and the Mtn Empire in the rain-shadowed area...with amounts of a quarter inch or so in the southern Shenandoah Valley area into central VA. This will set the stage for additional rainfall coming later Wednesday evening and particularly Thursday, in association with the approach of Michael. Coordinated with NWS Greer on a Flash Flood Watch which has been posted for the NC Mountains counties (Wilkes, Alleghany, Ashe and Watauga Counties) beginning at 2 pm Wednesday, ending early Thursday evening. Highs mainly in the low to mid 70s. Forecast confidence is moderate. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 400 AM EDT Tuesday... Primary focus is the track and anticipated rainfall footprint from Hurricane Michael. In general, model guidance is in reasonable agreement, featuring a highly amplified upper air pattern with an anomalous subtropical ridge of high pressure off the Mid-Atlantic Coast, and a deep longwave trough over the southern Plains. Caught in- between is Hurricane Michael over the eastern Gulf of Mexico which is forecast to gain latitude in a proverbial sling shot between the two upper air features. Latest track guidance suggests the center of Michael will bisect the Florida Panhandle Wednesday afternoon/evening then trek northeast across south central GA and into the Carolinas Wed-night and Thursday. A generous amount of moisture is forecast into our forecast area Thursday as the center of the system passes to our southeast... an axis of heavy rainfall occurring within the northwest quadrant of the storm where the low level winds converge with the increasing westerly winds aloft. Attm we are forecasting a general 1-3 inches of rain across the forecast area with the higher amounts along and east of the Blue Ridge. There are two areas which may see locally higher amounts... one being the Blue Ridge Parkway southwest of Roanoke into the NC high country where the southeast upslope wind component will be a premium before the storm arrives. The second area to watch will be over the NC/VA Piedmont on the northwest side of the storm track where convergent flow will be maximized...CLT-GSO-DAN corridor. If all comes to fruition, watershed within our CWA which will have the most impact from runoff would be the Dan River Basin. Wind impacts for our County Warning Area (CWA) from this system may be felt more so on the back side of the storm as it exits the region Thursday night and Friday. Direct impact from core tropical storm strength winds will occur along the central track of the storm (southeast of our CWA). However, as the storm moves rapidly to the northeast and away from the area Thursday night, pressure rises in the wake of the system across our mountains, in addition to the passage of a surface front will bring strong cross barrier flow with 85h winds of near 40 kts. This will result in gusty surface winds, similar to a strong frontal passage, across our CWA Thursday night and Friday with gusts of 20 to 30 mph. A noticeable airmass change will take place Thursday night into Friday. A surface front associated with the upper trough to our west will finally makes its entrance, northwest winds quickly introducing an airmass change that will reflect much lower dewpoints and cooler temperatures. These temperatures/dewpoints will be a seasonal eyeopening change, more of a reflection of what mid October should actually feel like weatherwise. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 400 PM EDT Tuesday... Upper level pattern will deflate over the weekend and into the following week as the Bermuda high becomes a summer ghost. One last surge of higher dewpoint air will try to work back into the area Sunday into Monday ahead of what will be the remnants of Hurricane Sergio, which is expected to get drawn into the southwestern CONUS from the Pacific Saturday, then into the base of the central CONUS long wave trough. Attm it appears the energy associated with this feature will pass through the OH valley Sunday with showers primarily to our northwest. However, with the passage of this feature it will open the door for a pattern change with the northern jet stream making a dive into the central and eastern CONUS, a feature that will favor below normal temperatures across much of the central and eastern U.S. by the middle of next week. As for the details, the upcoming weekend as a whole does not look that bad...featuring dry conditions and near seasonal temperatures. Near seasonal temperatures however, means temperatures at night will be in the 40s, so it will feel noticeably cooler compared to our extended summer-like nights. By Monday, showers associated with the deepening upper level trough to our northwest are expected to move across the area. After dries out for the middle of next week, but expect much cooler nights with the potential for frost in some areas toward 18th of the month. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... As of 738 PM EDT Tuesday... Poor flying conditions expected tonight into Wednesday with areas of rain, drizzle and fog. Southeast upslope flow will continue areas of rain, drizzle and fog tonight into Wednesday. Conditions will drop to MVFR/IFR in pockets of rain and fog. The general VFR conditions will lower to MVFR and IFR overnight into Wednesday. The more persistent MVFR/IFR will prevail along or near the Blue Ridge. Expect ceilings to at least partly obstruct the Blue Ridge ridgetops. Southeast winds again remain around 6-10 kts. Toward early Wednesday morning, an increased southeasterly jet of 35-40 kts will likely contribute to development of choppy conditions and mechanical turbulence near ridgetop level along the southern Blue Ridge south of Roanoke, and into the hilltops of southeastern WV and the New River Valley. Worst flight category conditions anticipated on Wednesday. Guidance shows good consistency in progressing a band of what should be moderate to potentially heavy rain at times from south to north along the spine of the Blue Ridge between 11-18z (and continuing into the late afternoon and evening hours). Expect ceilings to lower to MVFR- IFR category with visbys largely VFR- MVFR, though will tend IFR at times in the steady and at times heavy rain. Confidence is average for the entire period, though is lower than average on ceilings and placement of dense fog for the overnight period. Extended Discussion... Showers are expected to increase in coverage by Wednesday night and Thursday as tropical moisture shifts northward ahead of Hurricane Michael and a cold front moving in from the west. Rain may be heavy at times Thursday. Conditions will improve back to VFR on Friday behind the front, then VFR over the weekend. && .HYDROLOGY... As of 1100 PM Tuesday... An inflow of deep tropical moisture will introduce the possibility of both flash flooding and, later, river flooding in the Wednesday afternoon through Friday time frame. A first round of heavy rain is expected to affect the Blue Ridge and foothills region on Wednesday afternoon/evening as winds shift southeasterly across the mid-Atlantic, carrying very deep moisture into the mountains. Two to three inches, with locally higher amounts, are expected along the crest of the Blue Ridge and may result in flash flooding in spots by Wednesday evening. A flash flood watch has already been issued for this region. After a brief decrease in rainfall on Wednesday night, rainfall coverage and intensity is expected to increase again on Thursday late morning/early afternoon with the approach of what is expected to be (by that time) Tropical Storm Michael. Weather forecast models are still indicating a variability of rainfall amounts depending on the track and speed at which the storm pushes across the Carolinas, but the most likely scenario indicates 2 to 4 inches across the Southside of Virginia and the Piedmont of North Carolina, where a flash flood watch has been posted. Convective bands with high rates of rainfall within a tropical environment will obviously present an enhanced flash flood threat, with the Weather Prediction Center calling for a slight to moderate risk of excessive rainfall during the Thursday to early Friday timeframe, mainly across the southeast one-third of our forecast area. The Dan and lower Roanoke river basins will be most heavily affected by rainfall from Michael, and it appears reasonable that points these rivers will experience at least minor flooding...again: all dependent on where the heaviest rainfall occurs. Lesser amounts are expected to the northwest to include the Greenbrier and James River basins, which should limit the flood threat there. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Flash Flood Watch from Thursday morning through late Thursday night for VAZ032-043-044-058. NC...Flash Flood Watch from Thursday morning through late Thursday night for NCZ003>006-020. Flash Flood Watch from Wednesday afternoon through Thursday evening for NCZ001-002-018-019. WV...None. && $$ SYNOPSIS...AL NEAR TERM...AL/KK/NF SHORT TERM...PM LONG TERM...PM AVIATION...AL/KK HYDROLOGY...NF/PC