Srain Posted January 15, 2012 Share Posted January 15, 2012 The 00Z GFES continues to advertise a very wet/snowy pattern for the Cascade and Northern Sierra Nevada Ranges. Flooding concerns may well be growing for the Sacramento Valley regions such as Redding on down to the Sacramento area if these totals verify... PRELIMINARY EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 857 AM EST SUN JAN 15 2012 VALID 12Z THU JAN 19 2012 - 12Z SUN JAN 22 2012 ...PERSISTENT HEAVY WINTER PCPN PATTERN FOR THE NWRN US INCLUDING NRN CA THIS WEEK... MODELS AND ENSEMBLES CONTINUE TO DEPICT REASONABLY SIMILAR LARGER SCALE FLOW EVOLUTIONS OUT THROUGH THE ERN PACIFIC INTO NORTH AMERICA. IN THIS UPCOMING TRANSITIONAL PATTERN...AN EMERGING AND INCREASINGLY MOIST AND PROGRESSIVE SRN STREAM WAVETRAIN ACROSS THE PACIFIC MID-LATITUDES TAKES AIM AT THE NWRN US/NRN CA THEN INLAND AND EASTWARD ACROSS THE REST OF THE LOWER 48...GRADUALLY MITIGATING NRN STREAM INFLUENCE. THE MODELS THOUGH WILL CONTINUE TO HAVE ISSUES WITH THE EXTENT OF STREAM INTERACTIONS WITH TRANSITION...ESPECIALLY WITH LOW LEVEL COLD AIR PENETRATION FROM CANADA INTO THE US VERSUS SURFACE LOW CYCLOGENESIS/TRACK. OVERALL...ECMWF MODEL GUIDANCE HAS BEEN MORE CONSISTENT THAN GFS GUIDANCE OVER THE PAST FEW DAYS IN THE 3-5 DAY TIME FRAME AT MORE MODERATE AND SMALLER SPATIAL SCALES...BUT ALONG WITH OTHER GUIDANCE CONTINUES TO OFFER SIGNIFICANT RUN TO RUN VARIANCE IN RECENT FLOW REGIMES AT LONGER 6-7 DAY TIME FRAMES. THIS CAN BE ATTRIBUTED TO INCREASINGLY PROBLEMATIC TIMING AND STREAM INTERACTION ISSUES AND IS AGAIN THE CASE TODAY. ENSEMBLE MEANS HAVE THEMSELVES BY NATURE OFFERED BETTER LONGER TERM CONTINUITY BUT HAVE NOT BEEN IMMUNE TO UNCHARACTERISTICALLY EVIDENT RUN TO RUN FLUXUATIONS IN THIS EMERGING TRANSITIONAL PATTERN. PLANNED WINTER RECON FLIGHTS VECTORED OUT FROM HAWAII TONIGHT MAY BE ABLE TO AID REDUCTION OF ERROR STARTING WITH TONIGHTS 00 UTC GUIDANCE RUNS. ACCORDINGLY AND WITH AN EYE ON MAINTAINING CONTINUITY...UPDATED HPC PRELIM MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS HAVE BEEN PRIMARILY DERIVED FROM THE 00 UTC ECMWF DAYS 3-5 WED-FRI IN A PERIOD OF BELOW NORMAL SOLUTION SPREAD AND UNCERTAINTY WITH THE FLOW BEFORE A RAPID TRANSITION TO MORE OF A BLEND OF THE 00 UTC GFS/ECMWF ENSEMBLE MEANS HEADING INTO NEXT WEEKEND ON DAYS 6/7 AS UNCERTAINTY BEYOND LARGER SCALES QUICKLY GROWS. Link to comment Share on other sites More sharing options...
Srain Posted January 15, 2012 Share Posted January 15, 2012 The 00Z Op Euro continues to advertise a potent storm with a sharp cold front near the 25th, +/- a couple of days and several 00Z GFES 500mb members are very suggestive of big changes lurking near the same time frame. The longer range GFES even suggests some very chilly air may be dislodged from Canada dropping S into the Intermountain West/Plains into late January/early February. Hopefully with the G-IV Winter Recon missions scheduled over the Pacific, additional data will provide valuable information for the volatile changes seen throughout the operational and ensemble guidance. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 15, 2012 Share Posted January 15, 2012 The PNA had fallen further today to -0.130. Its decline is forecast to continue. For those who are interested, snow has been falling in and around the Seattle area. Parts of King County have actually picked up close to 6" snow. Seattle should see a minor accumulation. The Tuesday-Wednesday event looks to be more potent. In that event, there remains a reasonable probability that Seattle could pick up 4" or more snow. Link to comment Share on other sites More sharing options...
Srain Posted January 15, 2012 Share Posted January 15, 2012 The PNA had fallen further today to -0.130. Its decline is forecast to continue. For those who are interested, snow has been falling in and around the Seattle area. Parts of King County have actually picked up close to 6" snow. Seattle should see a minor accumulation. The Tuesday-Wednesday event looks to be more potent. In that event, there remains a reasonable probability that Seattle could pick up 4" or more snow. Don, an additional Winter RECON mission has been scheduled for 1/17 and hopefully that additional data will provide further 'fine tuning' for the Pacific NW and CA forecasts... WEATHER RECONNAISSANCE FLIGHTS CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL. 1100 AM EST SUN 15 JANUARY 2012 SUBJECT: WINTER STORM PLAN OF THE DAY (WSPOD) VALID 16/1100Z TO 17/1100Z JANUARY 2012 WSPOD NUMBER.....11-046 I. ATLANTIC REQUIREMENTS 1. NEGATIVE RECONNAISSANCE REQUIREMENTS. 2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE. II. PACIFIC REQUIREMENTS 1. FLIGHT ONE --NOAA 49 -- A. P31/ 37.7N 175.0W/ 17/0000Z B. NOAA9 03WSC TRACKP31 C. 16/1830Z D. 15 DROPS AS SHOWN ON TRACK E. 40,000 TO 45,000FT/ 17/0600Z Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 16, 2012 Share Posted January 16, 2012 Some quick thoughts: 1. No big changes since my thoughts posted in Message #548 for the January 24-31 timeframe are in order. The Objective Analogs centered at 1/26 rolled forward 1 day, the ECMWF forecast for the MJO through 1/29, and the NAEFS all continue to paint a mild picture across much of the U.S., Ontario, and Quebec. 2. Boston had a low temperature of 6° this morning. That is its first single-digit minimum temperature this winter. Last winter saw two single-digit readings, one of which was a low temperature of -2° on January 24, 2011. Winter 2001-02 had no single-digit readings. That winter's lowest reading was 13° on February 12, 2002. Furthermore, Boston has not had a winter with 10 or more single-digit lows since Winter 2006-07 when there were 10 such readings, four of which occurred in March. Tonight will be another cold night, but milder air will be returning. 3. Seattle received its first accumulating snow of the winter today. Through 5 pm PST, 2.2" had been reported at Seattle-Tacoma Airport. A moderate or even significant snowfall is a growing possibility for the greater Seattle area Tuesday into at least part of Wednesday. 4. Perhaps the biggest story in coming days will be the excessive precipitation that remains likely from central California northward to Washington. Link to comment Share on other sites More sharing options...
Srain Posted January 16, 2012 Share Posted January 16, 2012 Some very impressive totals continue to be advertised by the 00Z GFES for the Pacific NW and N CA. Winter RECON missions should continue to add valuable data for guidance ingest the next few days and there remains a potential severe weather event for the Plains near the 25th, +/- a couple of days as well. Link to comment Share on other sites More sharing options...
iceman56 Posted January 16, 2012 Share Posted January 16, 2012 Upwards of 15' of snow forecasted through Thursday in the Mt. Rainier area with more to come afterward. Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 16, 2012 Share Posted January 16, 2012 This morning, the PNA was -0.428. It continues to fall and will likely be lower than -0.500 when the possible Tuesday-Wednesday snow event occurs in Seattle. The potential exists for 4" or more snow and there is a growing risk of 6" or more. The relevant scatter diagram for Seattle's 6" snowstorms is below: Notice the cluster that appears when the ENSO Region 3.4 anomalies are in the -1.0°C to -0.5°C range and the PNA is in the -1.25 to -0.50 range. The latest weekly figure for the ENSO Region 3.4 anomaly was -1.0°C. The National Weather Service has issued a winter storm watch for Seattle. In part, the watch states: SOME AFFECTED LOCATIONS...SEATTLE...EVERETT...OLYMPIA...BELLINGHAM...PORT ANGELES. * TIMING...WEDNESDAY INTO WEDNESDAY EVENING. * SNOW ACCUMULATIONS...SPECIFIC SNOW ACCUMULATIONS ARE TOUGH TO PIN DOWN AT THIS POINT BUT THE POTENTIAL FOR A SIGNIFICANT SNOW EVENT FOR THE LOWLANDS EXISTS WEDNESDAY INTO WEDNESDAY EVENING. Link to comment Share on other sites More sharing options...
Srain Posted January 16, 2012 Share Posted January 16, 2012 The 12Z Op GFS continues to suggest a potent storm crossing the Great Basin/Southern Rockies/Plains near the 25th. It will be interesting to follow this event in the days ahead as it has the potential to be a major weather news event for late January... Link to comment Share on other sites More sharing options...
am19psu Posted January 16, 2012 Author Share Posted January 16, 2012 Our severe guys are starting alert clients in the Lower MS Valley for that time period, Steve Link to comment Share on other sites More sharing options...
donsutherland1 Posted January 16, 2012 Share Posted January 16, 2012 Our severe guys are starting alert clients in the Lower MS Valley for that time period, Steve Thanks for this update. The guidance has been quite persistent about the possibility of severe weather in the warm sector. It will be interesting to see whether the outbreak materializes and how large it might be. Link to comment Share on other sites More sharing options...
Srain Posted January 16, 2012 Share Posted January 16, 2012 The 12Z Euro continues to advertise a severe weather event near the 25th. While that model has been on the southern edge of the track, it is noteworthy that run to run consistency and additional Winter RECON data lends credence that such an event may well be ahead during that time frame. Link to comment Share on other sites More sharing options...
bluewave Posted January 16, 2012 Share Posted January 16, 2012 While the Euro looks overdone with the strength of the high to the north, a big high holding on over SE Canada would result in icing close to and north of the Canadian Border. Link to comment Share on other sites More sharing options...
Go Kart Mozart Posted January 16, 2012 Share Posted January 16, 2012 While the Euro looks overdone with the strength of the high to the north, a big high holding on over SE Canada would result in icing close to and north of the Canadian Border. That's an impressive CAD going on there. I would think that the atmosphere below 850 is quite cold, with an ice threat well south of the border. Link to comment Share on other sites More sharing options...
winterymix Posted January 16, 2012 Share Posted January 16, 2012 Could this be a repeat of the icy 1994 pattern? Notice deepening low pressure in the Midwest -- 988 mb low near Missouri -- running into the Quebec area high of 1053 mb. This seems like a rather severe event with potential damaging winds, ice and eventual loss of power for large areas. Link to comment Share on other sites More sharing options...
wxmx Posted January 16, 2012 Share Posted January 16, 2012 How bad it has been for south of 40N near the east coast that the 12z Euro @day 10 has a negative tilted trough with base south of Houston...Someone will probably correct me, but that would be a first in memory if verified...which of course it won't. Link to comment Share on other sites More sharing options...
wxmx Posted January 16, 2012 Share Posted January 16, 2012 One thing to note, is that the -PNA looks short lived, as the trough apparently splits, with a s/w digging south and then sweeping east, and the bulk of the trough retrograding W. That would yield a pattern similar to what we have had most of the winter, with the coldest anomalies near the S Rockies and the C and S Plains Link to comment Share on other sites More sharing options...
okie333 Posted January 17, 2012 Share Posted January 17, 2012 Could this be a repeat of the icy 1994 pattern? Notice deepening low pressure in the Midwest -- 988 mb low near Missouri -- running into the Quebec area high of 1953 mb. This seems like a rather severe event with potential damaging winds, ice and eventual loss of power for large areas. WOW seriously?!?! Link to comment Share on other sites More sharing options...
usedtobe Posted January 17, 2012 Share Posted January 17, 2012 As Raleighwx (alan) alluded to in his blog today. The gefs ens mean is showing signs of the pattern shifting back to a more seasonally cool pattern towards the beginning of Feb. Note on the 18Z 384 hr forecast that the ens mean build heights over greenland while also having lower than normal heights over the eastern U.S. That's a negative NAO look. Possibly just as important are the signs that the AL low and it's strong negative height departures might start shifting west. If the departure gets to the Aleutians that would allow room for ridging to develop along the west coast changing the negative PNA back to a positive one. It would only be weakly positive something we've seen quite a big this year but never with a negative NAO. A 384 hour ens mean still is way out there and could be quite different in a day or two. I'd be interested in what the euro ens mean shows that far out and whether it also shows signs of the negative NAO. Link to comment Share on other sites More sharing options...
HM Posted January 17, 2012 Share Posted January 17, 2012 This late Jan / early February return of winter is becoming more and more legitimate. Anyone notice the latest EP vectors forecast from the ECMWF? Lower stratosphere is not exactly equatorward either lately.... Link to comment Share on other sites More sharing options...
HM Posted January 17, 2012 Share Posted January 17, 2012 I am enjoying this current warming: Link to comment Share on other sites More sharing options...
Weathergun Posted January 17, 2012 Share Posted January 17, 2012 70mb temps have risen well above average between 60-90N as well. But I thought, that most of this warming was occuring mostly over the Asia side. Which is why our pattern along the East Coast, won't change this month: http://acdb-ext.gsfc..._2011_merra.pdf Also the EP flux in the trophosphere has been going in all in both euatorward and poleward directions, of late: http://ds.data.jma.g.../ep_12z_nh.html Link to comment Share on other sites More sharing options...
HM Posted January 17, 2012 Share Posted January 17, 2012 70mb temps have risen well above average between 60-90N as well. But I thought, that most of this warming was occuring mostly over the Asia side. Which is why our pattern along the East Coast, won't change this month: Why do you think that? Link to comment Share on other sites More sharing options...
Srain Posted January 17, 2012 Share Posted January 17, 2012 It's good to see some great discussions within this thread. Pinned worthy, IMO. Link to comment Share on other sites More sharing options...
winterymix Posted January 17, 2012 Share Posted January 17, 2012 WOW seriously?!?! Thanks, I deserved it; and fixed my post. Link to comment Share on other sites More sharing options...
Weathergun Posted January 17, 2012 Share Posted January 17, 2012 Why do you think that? The warming that's progagted down to 500mb, that's causing the ridge to develop over Alletiuans and Bering Straight right now. Instead of spread over the NAO regions, this ridge forecast by the models retrograde into Central Siberia. Link to comment Share on other sites More sharing options...
BethesdaWX Posted January 17, 2012 Share Posted January 17, 2012 The warming that's progagted down to 500mb, that's causing the ridge to develop over Alletiuans and Bering Straight right now. Instead of spread over the NAO regions, this ridge forecast by the models retrograde into Siberia. That doesn't mean Asian sourcing won't change the pattern here in the longer ranges, signal just has to progress over the hemisphere anomaly by anomaly. Link to comment Share on other sites More sharing options...
Srain Posted January 17, 2012 Share Posted January 17, 2012 NCEP Operational Status Message Tue Jan 17 03:09:59 2012 GMT NOUS42 KWNO 170309 ADMNFD SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD 0308Z TUE JAN 17 2012 THE 00Z GFS MODEL HAS STARTED AND IS RUNNING ON TIME. 15 PACIFIC OCEAN NOAA G-IV DROPSONDES WERE AVAILABLE FOR INGEST. $$ HANDEL/SDM/NCO/NCEP Link to comment Share on other sites More sharing options...
CoastalWx Posted January 17, 2012 Share Posted January 17, 2012 The EC ensembles also try to weaken the AK low and pull it nw just a little bit. It is stronger on the EC ensembles as compared to the GEFS. In terms of the west, the 12z GEFS had more zonal wnw to ese flow and did not feature troughing by the end of the period. This lead to lower heights across the east thanks to the blocking that was referenced by Wes and others. The euro ensembles have some weak troughing across the southwest which causes heights not to lower as much across the east, especially se, due to some pumping up of the heights that would naturally occur...although I would not call it a se ridge quite yet. But, they do show some ridging across the Davis Straits. This whole thing would agree with the euro weeklies which do try to retrograde the big AK low and replace it with higher heights. The pattern is definitely not 2009-2010 by any means..lol, but there is some improvement. Hopefully we can lift the low out, because it is tainting the atmosphere somewhat with zonal flow, but anytime you have a trough in the east in Feb...things can happen. Link to comment Share on other sites More sharing options...
Ji Posted January 17, 2012 Share Posted January 17, 2012 The EC ensembles also try to weaken the AK low and pull it nw just a little bit. It is stronger on the EC ensembles as compared to the GEFS. In terms of the west, the 12z GEFS had more zonal wnw to ese flow and did not feature troughing by the end of the period. This lead to lower heights across the east thanks to the blocking that was referenced by Wes and others. The euro ensembles have some weak troughing across the southwest which causes heights not to lower as much across the east, especially se, due to some pumping up of the heights that would naturally occur...although I would not call it a se ridge quite yet. But, they do show some ridging across the Davis Straits. This whole thing would agree with the euro weeklies which do try to retrograde the big AK low and replace it with higher heights. The pattern is definitely not 2009-2010 by any means..lol, but there is some improvement. Hopefully we can lift the low out, because it is tainting the atmosphere somewhat with zonal flow, but anytime you have a trough in the east in Feb...things can happen. Link to comment Share on other sites More sharing options...
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