Srain Posted November 12, 2011 Share Posted November 12, 2011 The medium range guidance has been suggesting a pattern change and hints of dropping some chilly air S that has been pooling in Alaska and Western Canada. While the GFS has been a bit more bullish on dropping a strong polar front S of the Canadian Border, the Euro seems to be trending to an agreement. MJO forcing seems favorable as well. Hopefully we can begin some discussions going regarding medium and longer range forecasts. We have a wealth of knowledge with our Red Tags as well as other knowledgeable members. My hunch is we may see the first real Winter Storm for the Plains near the Thanksgiving time frame. Link to comment Share on other sites More sharing options...
mnweather Posted November 12, 2011 Share Posted November 12, 2011 It appears the GGEM is also showing the development of a winter storm toward 192 hours. To my untrained eye it looks like the ECMWF ensemble mean just bogs things down in the southwest. Long way to go though so we will see but something to keep your eye on. Maybe a red tagger can chime in with some good analysis. Link to comment Share on other sites More sharing options...
JoMo Posted November 12, 2011 Share Posted November 12, 2011 Pattern shows a SE Ridge with a NW trough. Should be a nice battle zone somewhere in between. Link to comment Share on other sites More sharing options...
andyhb Posted November 12, 2011 Share Posted November 12, 2011 18z GFS at 192 hrs has 60s SFC dews (SBCAPE of 750-1000 J/kg) being advected as far north as N. Central Iowa This in association with impressive winds aloft (40-60 kts at H85, 60-80 kts at H5), and well, I think you can fill in the rest... Link to comment Share on other sites More sharing options...
prinsburg_wx Posted November 13, 2011 Share Posted November 13, 2011 from BIS AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE BISMARCK ND 304 PM CST SUN NOV 13 2011 FRIDAY THROUGH SUNDAY...AS THE COLD AIR RETURNS BEHIND THE AFOREMENTIONED COLD FRONTAL PASSAGE FRIDAY...EXPECT SOME FLURRIES OR A COUPLE OF SNOW SHOWERS. THE COLD AIR REMAINS IN PLACE THROUGH FRIDAY NIGHT AS THE UPPER LEVEL FLOW BECOMES SOUTHWESTERLY...AHEAD OF AN EJECTING UPPER/SFC LOW PRESSURE FROM THE PACIFIC COAST. THIS IS FORECAST TO MOVE INTO THE NORTHERN HIGH PLAINS SATURDAY AND EXIT SUNDAY. THIS LOW HAS BEEN CONSISTENT FOR A COUPLE OF DAYS NOW. CONCUR WITH THE CONSISTENT ALLBLEND WITH MID TO HIGH END CHANCE POPS OVER WESTERN NORTH DAKOTA. THE TRACK OF THE SURFACE LOW AND HEAVIEST SNOW WILL CONTINUE TO SHIFT DAILY...BUT AGREEMENT FOR A WIDESPREAD WEEKEND SNOWSTORM REMAINS A CONCERN AND WILL BE WATCHED CLOSELY OVER THE NEXT SEVERAL DAYS. from DVN AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE QUAD CITIES IA IL 309 PM CST SUN NOV 13 2011 FRIDAY NIGHT THROUGH SUNDAY...INTERESTING SITUATION AS MAJOR TROUGH IN THE WESTERN UNITED STATES PUMPS GULF MOISTURE INTO THE MIDWEST ON A PERSISTENT STRONG LOW LEVEL JET. DEPENDING ON HOW FAST THE MOISTURE RETURN IS THERE COULD BE ISOLATED THUNDERSTORMS LATE FRIDAY NIGHT NORTH OF I-80. THIS WOULD BE OCCURRING WITH STRONG WARM ADVECTION ON THE NOSE OF THE LOW LEVEL JET. CONTINUED FEED OF WARM MOIST AIR DUE TO A DEEP SOUTHWEST FLOW ALOFT SHOULD ALLOW FOR DESTABILIZATION OF THE ATMOSPHERE WITH SHOWALTERS WELL INTO THE NEGATIVE NUMBERS. WILL MENTION CHANCES FOR SHOWERS AND THUNDERSTORMS FOR THE WEEKEND...WITH LIKELY POPS SUNDAY NIGHT AS STRONG COLD FRONT ARRIVES. TEMPERATURES WILL RISE THROUGH THE WEEKEND WITH MAX TEMPS ON SUNDAY WELL INTO THE 60S IF NOT 70+. GIVEN THE SYNOPTIC PATTERN WITH SUCH STRONG WIND FIELDS PROGGED BY THE ECM A RATHER UNUSUAL LATE NOVEMBER SEVERE WEATHER EVENT IS POSSIBLE. STAY TUNED. Link to comment Share on other sites More sharing options...
brettjrob Posted November 13, 2011 Share Posted November 13, 2011 GFS and ECMWF are currently in agreement that a significant wrn US trough will evolve next weekend while a ridge pumps over the GOM and Southeast. The pattern looks favorable for unseasonably-strong moisture return, much like we saw this past week with the OK event. Lots of time for changes, of course, but both models indicate >60 F surface dew points in place over a large swath of the central US by Sunday. Link to comment Share on other sites More sharing options...
Srain Posted November 15, 2011 Author Share Posted November 15, 2011 A bit too early for a thread of its own, but there does appear to be a chance for some severe weather across the S Plains next week. Something to watch. Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 15, 2011 Share Posted November 15, 2011 A bit too early for a thread of its own, but there does appear to be a chance for some severe weather across the S Plains next week. Something to watch. Day 10 Euro is something to behold... Operational GFS similar, but much less amplified, but perhaps that is a result of the truncation at hour 192. Link to comment Share on other sites More sharing options...
radarman Posted November 15, 2011 Share Posted November 15, 2011 The new Langley Hill nexrad was made for nights like tomorrow. Link to comment Share on other sites More sharing options...
prinsburg_wx Posted November 16, 2011 Share Posted November 16, 2011 Larry Cosgrove - Nov 16, 2011 Houston Weather ExaminerAs for the Thanksgiving holiday weekend itself, I am very concerned that a truly major storm will form, moving along that familiar route from Amarillo TX to Montreal QC. That could mean all kinds of problems for travelers, with snowfall in parts of the Midwest and Great Lakes, heavy rain and severe thunderstorms from the lower/middle Great Plains into the Northeast, and strong winds in many U.S. locations. Followed by a stronger push of cold air just in time for the first full week of gift shopping. Link to comment Share on other sites More sharing options...
brettjrob Posted November 16, 2011 Share Posted November 16, 2011 I jinxed the early-week threat, but that ECMWF image for 240 hr. sure does look tasty. <-- haven't learned my lesson Link to comment Share on other sites More sharing options...
David Reimer Posted November 16, 2011 Share Posted November 16, 2011 I jinxed the early-week threat, but that ECMWF image for 240 hr. sure does look tasty. <-- haven't learned my lesson Link to comment Share on other sites More sharing options...
andyhb Posted November 16, 2011 Share Posted November 16, 2011 Well, the GFS has been all over the place with several of these recent systems, FWIW. I jinxed the early-week threat, but that ECMWF image for 240 hr. sure does look tasty. <-- haven't learned my lesson If only it wasn't that far out... Link to comment Share on other sites More sharing options...
andyhb Posted November 16, 2011 Share Posted November 16, 2011 00z GFS certainly coming in a bit more amplified with that system in the medium range (9-10 days). Euro maintains a large trough during the same time period. Link to comment Share on other sites More sharing options...
prinsburg_wx Posted November 17, 2011 Share Posted November 17, 2011 FWIW: tonights 0z GGEM has the black friday storm...HR 204 - 228 Link to comment Share on other sites More sharing options...
andyhb Posted November 17, 2011 Share Posted November 17, 2011 FWIW: tonights 0z GGEM has the black friday storm...HR 204 - 216 GFS also has a strong storm/trough at this period, although not as deep as that... Link to comment Share on other sites More sharing options...
WxMidwest Posted November 17, 2011 Share Posted November 17, 2011 LC said something about Thanksgiving/Black Friday Storm for Great Lakes/Midwest.... Interesting bit of cyclogenesis there.. Link to comment Share on other sites More sharing options...
prinsburg_wx Posted November 17, 2011 Share Posted November 17, 2011 LC said something about Thanksgiving/Black Friday Storm for Great Lakes/Midwest.... Interesting bit of cyclogenesis there.. yeah he's hit on it hard the last couple of nights in his discussions. Link to comment Share on other sites More sharing options...
andyhb Posted November 17, 2011 Share Posted November 17, 2011 Euro in agreement as well, closer to the GFS strength. Link to comment Share on other sites More sharing options...
brettjrob Posted November 17, 2011 Share Posted November 17, 2011 Euro in agreement as well, closer to the GFS strength. Ehhhh... it looks like garbage to me. The mid-week system digs in and closes off along the east coast, which no doubt would preclude any appreciable moisture return for the Fri-Sat timeframe. There's far too little spacing between the two troughs, taken verbatim. Link to comment Share on other sites More sharing options...
andyhb Posted November 17, 2011 Share Posted November 17, 2011 Ehhhh... it looks like garbage to me. The mid-week system digs in and closes off along the east coast, which no doubt would preclude any appreciable moisture return for the Fri-Sat timeframe. There's way too little spacing between the two troughs, taken verbatim. Agreed on that front, I was just talking about the general depth/profile of the trough. That cut off would just kill any svr potential (and possibly any appreciable snow potential) anywhere... Link to comment Share on other sites More sharing options...
Srain Posted November 17, 2011 Author Share Posted November 17, 2011 SPC has N Central TX pegged for severe weather chances on day 5. Still some uncertainty in regards to how strong the Baja Low will be, but Gulf return is looking better, so severe weather chances may increase across OK/AR in the warm sector and with the Thanksgiving Holiday travel period ahead, it may be worthy of its own thread... Link to comment Share on other sites More sharing options...
Srain Posted November 18, 2011 Author Share Posted November 18, 2011 There has been some chatter of a pattern change beyond the Thanksgiving time frame and Wes (usetobe) has a discussion going on the main page concerning this. The ensembles are suggesting the Alaska vortex weakening and shifting over time and some suggestions of a weak +PNA regime becoming established. There are also some hints of rising heights near Greenland, suggesting a bit of a blocking pattern. This would tend to pop some ridging in the W. The big question is will this be a transient pattern or just a brief flip from what we have seen? There has been a lot of cold air building across Alaska under the PV anomaly, but will the pattern permit that cold to transport S as the Ridge builds? A lot of questions remain, but at least it's something to monitor has we head beyond next week and transition into December. Link to comment Share on other sites More sharing options...
nrgjeff Posted November 18, 2011 Share Posted November 18, 2011 Starting to get better evidence for the long awaited pattern change. Good post below. Thanksgiving week may be transitory southern stream action. It can happen, even during La Nina. After the start of Dec it could be more of a full latitude trough in the Plains. I'm not saying 2000 or 1989, but a variable coldish pattern perhaps. The distant ensembles do indeed show the PNA going positive. Just got some weekly Euro charts that go through mid-Dec. East Pac ridge pumps up, but not all the way into AK. Greenland ridge is a bit south; odd but not unprecedented. Plains sandwiched in between should get cold in Dec. Blue Norther for Texas? Believe the Northeast USA would stay mild/normal with Greenland ridging displaced south. Southeast USA normal? My SE group is all excited, but I believe this is a Plains and Texas event at least the first half of Dec. I grew up in the Plains. Many a mild Thanksgiving have been followed by a Dec polar pig. Enjoy! There has been some chatter of a pattern change beyond the Thanksgiving time frame and Wes (usetobe) has a discussion going on the main page concerning this. The ensembles are suggesting the Alaska vortex weakening and shifting over time and some suggestions of a weak +PNA regime becoming established. There are also some hints of rising heights near Greenland, suggesting a bit of a blocking pattern. This would tend to pop some ridging in the W. The big question is will this be a transient pattern or just a brief flip from what we have seen? There has been a lot of cold air building across Alaska under the PV anomaly, but will the pattern permit that cold to transport S as the Ridge builds? A lot of questions remain, but at least it's something to monitor has we head beyond next week and transition into December. Link to comment Share on other sites More sharing options...
Srain Posted November 19, 2011 Author Share Posted November 19, 2011 Medium range guidance suggests a rather robust UL crossing the Baja and ejecting ENE across the S Plains. The one concern I have will be with such quick return Gulf moisture, so a true severe outbreak may be dampened. There does appear to be a cold pocket aloft associated with this disturbance which could add to the dynamics, so it does warrant some attention. It appears that a squall line would be the primary threat for this disturbance as well as very windy/cool conditions to end the long Thanksgiving Holiday period. Link to comment Share on other sites More sharing options...
Srain Posted November 19, 2011 Author Share Posted November 19, 2011 HPC Final Update suggests some interesting travel condition for the pre/post Thanksgiving Holiday Weekend...we will see... EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 124 PM EST SAT NOV 19 2011 VALID 12Z TUE NOV 22 2011 - 12Z SAT NOV 26 2011 AS A POLAR VORTEX DROPS SWWD INTO AK CHANGING THE PACIFIC FLOW PATTERN THE OPERATIONAL MODELS ARE IN FAIR AGREEMENT TAKING AN OUTSIDE SLIDER SHORTWAVE DOWN ALONG THE CA COAST IN THE SHORT RANGE PERIOD AND EXITING IT EASTWARD THRU THE SRN PLAINS MON/TUES AND TOWARDS AND OFF THE EAST COAST LATE WEDNESDAY AND THURSDAY. SECOND MAJOR FULL LATITUDE TROF FROM THE GLFAK TO WEST OF BAJA AFFECTS THE WEST COAST WED AND THURSDAY REACHING THE PLAINS OVER THE WEEKEND. THE LEAD SYSTEM INDUCES SOUTHWESTERN CONUS CYCLOGENESIS LATE MONDAY WITH LOW PRESSURE MOVING THRU CENTRAL MS AND LOWER OH VALLEY REGION LATE TUES. OPERATIONAL 00Z/06Z GFS AND 00Z ECMWF PHASES NRN STREAM FLOW WITH THE SEPERATE SRN STREAM SHORTWAVE INTO A MORE FULL LATITUDE TROF AND PROGRESS IT EASTWARD WITH MORE ENERGY DIGGING INTO MID TROF BY THE ECMWF WHICH IT HAS DONE IN VARYING DEGREES AND LOCATIONS FOR THE PAST SEVERAL RUNS. THIS RESULTS IN A FASTER AND OFFSHORE MUCH MORE NRN SFC SOLUTION BY GFS. 00Z ECMWF KEEPS ONE PRIMARY STRONG SFC LOW COMING OUT THRU THE NY BIGHT AND OFF NOVA SCOTIA THURSDAY FOLLOWED BY STRONG WINDY COLD ADVECTION CONDITIONS OVER THE EAST COAST. CMC/UKMET/NOGAPS KEEP MORE SEPERATION BETWEEN THE NRN AND SRN STREAMS RESULTING IN A MUCH FARTHER SOUTH SFC LOW COMING OUT THRU THE CAROLINAS OR VA WED AND OFF THE MID ATLC COAST THURSDAY. SFC LOW ENSEMBLE SPREAD IS VERY WIDE WITH A CONSIDERABLE NUMBER OF ECMWF ENSEMBLES CLOSER TO THE CMC/UKMET SOLUTION WITH ANOTHER STRONG CLUSTERING TO THE NORTH. THIS REMAINS QUITE UNCERTAIN AND THERE MAY WELL BE TWO SYSTEMS EJECTING HERE. PREFER TO KEEP A SECOND WAVE/SFC LOW AS A REFLECTION OF THE SWRN STREAM STREAM SYSTEM COMING OUT FARTHER SOUTH AND AFFECTING THE MID ATLC SOUTHEAST SEABOARD ON THURSDAY FOLLOWED BY IMPROVING CONDITIONS FRI AND SAT. SECOND DEEP FULL LATITUDE TROF COMING INTO THE WEST AND TO THE PLAINS IN A WEEK BETTER AGREED UPON. 12Z GUIDANCE OF GFS IS CONSISTENT WITH ITS PRIOR RUN. LATEST UKMET AND CMC CHANGE AGAIN ALONG THE EAST COAST WITH CMC NOW SHOWUNG STREAM PHASING AND LOKING LIKE THE OVERNIGHT 00Z ECMWF WITH A STRONG STORM OFF THE NEW ENGLAND COAST THURSDAY. UKMET HAS DAMPENED IT STRONGER SRN STREAM SHORT INTO A PROGRESSIVELY EXITING NRN ONE. THESE DIFFERENCES JUST ADD TO THE UNCERTAINTY WHILE STILL SHOWING THE POTENTIAL OF A STRONGER AND CLOSR IN SYSTEM ALONG THE EASTERN SEABOARD THURSDAY. HPC UPDATED MORNING PRELIM AND AFTN FINAL SOLUTIONS BASED ON ECMWF FOR DAY 3 TUES AND A BLEND OF 00Z GFS AND 00Z ECMWF ENS MEANS FOR DAYS 4-7 WED/SAT. THIS WAS MODIFIED FOR SLIGHTLY MORE LOW PRESSURE OFF THE MID ATLC COAST DAY 5 THURSDAY. EXPECT MDT/HVY RAINS OK/EAST TX/MO/AR INTO THE LOWER OH VALLEY TUESDAY SPREADING EASTWARD INTO THE APPLCHNS AND TO THE COAST BY LATE WEDNESDAY. NRN PERIPHERY ACROSS HIGHER TERRAIN OF NY/AND NEW ENG MAY SEE SOME ACCUMULATING SNOW. BREEZY CONDITIONS WITH SOME LINGERING RAIN POTENTIAL MID ATLC AND SOUTHEAST SEABOARD NORTH OF FL THANKSGIVING DAY. HEAVY RAINS AND HIGH WINDS SWRN B.C./VANCOUVER ISLAND AND COASTAL WA AND OR TUES AND WED. RAINS SPREADING DOWN THE COAST INTO CENTRAL AND SOCAL THURSDAY/THANKSGIVING WITH LIGHTER AMOUNTS REACHING INTO THE GREAT BASIN. FRIDAY WILL SEE WIDESPREAD UNSETTLED CONDITIONS ENTIRE WEST INCLUDING SNOW THROUGH OUT THE ROCKIES. HVY RAIN POTENTIAL DEVELOPING IN THE SRN AND POSSIBLY CENTRAL PLAINS FRI AND SAT AND POSSIBLY REACHING THE MS VALLEY BY SATURDAY AS A DEEP TROF APPROACHES WITH LOTS OF MID AND LOW LEVEL GULF MOISTURE INFLOW. Link to comment Share on other sites More sharing options...
Srain Posted November 20, 2011 Author Share Posted November 20, 2011 The 00Z guidance continue to advertise a full latitude trough next weekend slowly progressing E. While it is still a bit too far out for its own thread, the indications are there for another mess for travelers for the Thanksgiving time frame. This UL looks to cause problems from the W PAC down to CA into the Rockies with heavy mountain snows and lower elevation rains. As the system spreads E, severe weather in the warm sector looks likely, if there is enough moisture return from the pre Thanksgiving (Tuesday-Wednesday) disturbance. Late next weekend could be a real mess for any travelers returning from the Mid West/EC areas, if it verifies. Link to comment Share on other sites More sharing options...
Srain Posted November 21, 2011 Author Share Posted November 21, 2011 Just perhaps we are beginning to see the pattern change after Thanksgiving. The Alaska Vortex has be displaced and weakened and a +PNA regime is beginning to show up via the long range Euro. We will see. Link to comment Share on other sites More sharing options...
trapperman Posted November 21, 2011 Share Posted November 21, 2011 Just perhaps we are beginning to see the pattern change after Thanksgiving. The Alaska Vortex has be displaced and weakened and a +PNA regime is beginning to show up via the long range Euro. We will see. Stop the presses. I thought there would be a lot more chatter after the 12z op Euro came out... massive retrograding low next week with enough cold air to make a lot of folks giddier than a schoolgirl... Link to comment Share on other sites More sharing options...
trapperman Posted November 21, 2011 Share Posted November 21, 2011 i gotta say both the Euro and the GFS for early next week are just... wacky. Link to comment Share on other sites More sharing options...
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