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February Winter Storm Prospects


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The morning HPC discussion is a low to no confidence outlook again

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

713 AM EST SUN JAN 29 2012

VALID 12Z THU FEB 02 2012 - 12Z SUN FEB 05 2012

GUIDANCE STILL HAS CONSIDERABLE DIFFICULTY IN RESOLVING SHRTWV

DETAILS CONTAINED WITHIN PROGRESSIVE LOW AMPLITUDE FLOW OVER THE

CONUS AS OF EARLY DAY 3 WED. ALSO... WHILE THERE IS GOOD

AGREEMENT AND CONTINUITY REGARDING THE GENERAL EVOLUTION OF AN

AMPLIFYING/SHARPENING ERN PAC TROF-WRN NOAM RIDGE PATTERN DURING

THE FIRST HALF OF THE MEDIUM RANGE PERIOD SOLNS DISPLAY INCREASING

DIVERGENCE WITH TIME REGARDING DOWNSTREAM FLOW. IN ADDITION SOME

DIFFS EXIST IN TERMS OF THE EXTENT TO WHICH ERN PAC TROF ENERGY

INTRUDES UPON THE WRN NOAM RIDGE BUT SPREAD IS LESS EXTREME WITH

THIS PART OF THE FCST VERSUS AREAS FARTHER EWD.

EARLY IN THE FCST... THE FACT THAT THE PAST TWO ECMWF RUNS ARE

NEARLY 180 DEGS OUT OF PHASE WITH SIGNIFICANT SHRTWVS ILLUSTRATES

THE UNCERTAINTY THAT IS ALREADY PRESENT EARLY WED. THE 00Z ECMWF

IN PARTICULAR COMPARES UNFAVORABLY TO OTHER MODEL/ENSEMBLE

GUIDANCE WITH ITS SHRTWV TRACKING FROM THE SRN ROCKIES INTO THE OH

VLY DURING WED THU... WITH THE LEADING RIDGE ALOFT OVER THE

NORTHEAST AS OF LATE THU COINCIDING WITH TROFS IN THE 00Z GEFS/12Z

ECMWF ENSEMBLE MEANS. THE 12Z CANADIAN MEAN HAS FLAT FLOW AT THAT

TIME/LOCATION. GFS SPECIFICS ARE STILL A QUESTION MARK BUT AT

LEAST OFFER A BETTER FIT TO OTHER GUIDANCE AS A WHOLE.

BY DAY 5 FRI GUIDANCE SPANS FROM THE SRN ROCKIES TO MS VALLEY FOR

THE AXIS OF AMPLIFYING CONUS TROF ENERGY. THE 00Z UKMET/CMC AND

12Z ECMWF CLUSTER WITH THE 12Z ECMWF ENSEMBLE MEAN OVER THE SRN

ROCKIES WHILE THE 00Z GFS/GEFS MEAN/ECMWF FAVOR THE ERN SIDE OF

THE SPREAD AND WITH A MORE ROUNDED OVERALL TROF. THE 12Z GFS HAD

BEEN A MEMBER OF THE WRN CLUSTER. IN ADDITION TO THE NEARLY EVEN

SPLIT IN GUIDANCE... THE RAPID SHARPENING/AMPLIFICATION OF THE WRN

NOAM RIDGE SEEMS TO FAVOR AT LEAST AN INTERMEDIATE TROF AXIS

VERSUS THE ERN SIDE OF THE ENVELOPE. HOWEVER OCCASIONAL BIASES

TOWARD EXCESSIVE WWD EXTENT OF SWRN CONUS ENERGY MIGHT FAVOR NOT

GOING COMPLETELY TO THE WRN GROUPING... THUS RECOMMENDING A

COMPROMISE BETWEEN THE TWO CLUSTERS.

ALONG THE WEST COAST THE GFS AND TO SOME EXTENT GEFS MEAN MAY BE A

LITTLE FAST TO BRING ERN PAC HGT FALLS TOWARD THE WRN STATES. THE

00Z ECMWF IS LIKELY AN IMPROVEMENT UPON THE 12Z RUN THAT BROUGHT A

DECENT SHRTWV INTO SWRN CANADA.

THE DAYS 3-7 WED-SUN FCST STARTS WITH AN EVEN BLEND OF THE

GEFS/12Z ECMWF ENSEMBLE MEANS AS THE BEST WAY TO RESOLVE VERY

UNCERTAIN SHRTWV DETAILS OVER THE CONUS AT THE START OF THE PERIOD

AND TO YIELD THE DESIRED INTERMEDIATE TROF AXIS POSN OVER THE

CNTRL CONUS BY LATE IN THE WEEK. THIS SOLN ALSO MAINTAINS THE

INTEGRITY OF THE WRN NOAM RIDGE FAIRLY WELL THRU THE PERIOD.

...UPDATED MORNING PRELIMS..ADDITIONAL GUIDANCE OF 06Z GFS/06Z

GEFS MEAN/LAGGED AVERAGE FORECASTS/ENSEMBLE CLUSTER GROUPINGS

CONTINUE TO CONCUR WITH ABOVE THINKING. A DIFFICULT AND LOW TO NO

CONFIDENCE FORECAST IN DETAILS LATE PERIOD MAINLY WITH THE ERN

CONUS TROF. BASED ON AN AMALGAM OF DAYS 6-7 SOLUTIONS THE 06Z GFS

ENS MEAN SHOULD BE INCORPORATED INTO THE SOLUTION AND SUPPORTS THE

EARLIER ABOVE USED OVERNIGHT MODEL BLEND. DEPICTION BY DAY 5 FRI

OF A CENTER JUMPING SFC LOW FROM THE OH VALLEY TO THE NC COAST AND

THAN AN EXIT NEWD TO NEAR THE NEW ENG BENCH MARK BY DAY 6 SAT

SEEMS REASONABLE AT THIS TIME ALBEIT WITH CONTINUED VERY LOW

CONFIDENCE.

RAUSCH/ROSENSTEIN

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The morning HPC discussion is a low to no confidence outlook again

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

713 AM EST SUN JAN 29 2012

VALID 12Z THU FEB 02 2012 - 12Z SUN FEB 05 2012

GUIDANCE STILL HAS CONSIDERABLE DIFFICULTY IN RESOLVING SHRTWV

DETAILS CONTAINED WITHIN PROGRESSIVE LOW AMPLITUDE FLOW OVER THE

CONUS AS OF EARLY DAY 3 WED. ALSO... WHILE THERE IS GOOD

AGREEMENT AND CONTINUITY REGARDING THE GENERAL EVOLUTION OF AN

AMPLIFYING/SHARPENING ERN PAC TROF-WRN NOAM RIDGE PATTERN DURING

THE FIRST HALF OF THE MEDIUM RANGE PERIOD SOLNS DISPLAY INCREASING

DIVERGENCE WITH TIME REGARDING DOWNSTREAM FLOW. IN ADDITION SOME

DIFFS EXIST IN TERMS OF THE EXTENT TO WHICH ERN PAC TROF ENERGY

INTRUDES UPON THE WRN NOAM RIDGE BUT SPREAD IS LESS EXTREME WITH

THIS PART OF THE FCST VERSUS AREAS FARTHER EWD.

EARLY IN THE FCST... THE FACT THAT THE PAST TWO ECMWF RUNS ARE

NEARLY 180 DEGS OUT OF PHASE WITH SIGNIFICANT SHRTWVS ILLUSTRATES

THE UNCERTAINTY THAT IS ALREADY PRESENT EARLY WED. THE 00Z ECMWF

IN PARTICULAR COMPARES UNFAVORABLY TO OTHER MODEL/ENSEMBLE

GUIDANCE WITH ITS SHRTWV TRACKING FROM THE SRN ROCKIES INTO THE OH

VLY DURING WED THU... WITH THE LEADING RIDGE ALOFT OVER THE

NORTHEAST AS OF LATE THU COINCIDING WITH TROFS IN THE 00Z GEFS/12Z

ECMWF ENSEMBLE MEANS. THE 12Z CANADIAN MEAN HAS FLAT FLOW AT THAT

TIME/LOCATION. GFS SPECIFICS ARE STILL A QUESTION MARK BUT AT

LEAST OFFER A BETTER FIT TO OTHER GUIDANCE AS A WHOLE.

BY DAY 5 FRI GUIDANCE SPANS FROM THE SRN ROCKIES TO MS VALLEY FOR

THE AXIS OF AMPLIFYING CONUS TROF ENERGY. THE 00Z UKMET/CMC AND

12Z ECMWF CLUSTER WITH THE 12Z ECMWF ENSEMBLE MEAN OVER THE SRN

ROCKIES WHILE THE 00Z GFS/GEFS MEAN/ECMWF FAVOR THE ERN SIDE OF

THE SPREAD AND WITH A MORE ROUNDED OVERALL TROF. THE 12Z GFS HAD

BEEN A MEMBER OF THE WRN CLUSTER. IN ADDITION TO THE NEARLY EVEN

SPLIT IN GUIDANCE... THE RAPID SHARPENING/AMPLIFICATION OF THE WRN

NOAM RIDGE SEEMS TO FAVOR AT LEAST AN INTERMEDIATE TROF AXIS

VERSUS THE ERN SIDE OF THE ENVELOPE. HOWEVER OCCASIONAL BIASES

TOWARD EXCESSIVE WWD EXTENT OF SWRN CONUS ENERGY MIGHT FAVOR NOT

GOING COMPLETELY TO THE WRN GROUPING... THUS RECOMMENDING A

COMPROMISE BETWEEN THE TWO CLUSTERS.

ALONG THE WEST COAST THE GFS AND TO SOME EXTENT GEFS MEAN MAY BE A

LITTLE FAST TO BRING ERN PAC HGT FALLS TOWARD THE WRN STATES. THE

00Z ECMWF IS LIKELY AN IMPROVEMENT UPON THE 12Z RUN THAT BROUGHT A

DECENT SHRTWV INTO SWRN CANADA.

THE DAYS 3-7 WED-SUN FCST STARTS WITH AN EVEN BLEND OF THE

GEFS/12Z ECMWF ENSEMBLE MEANS AS THE BEST WAY TO RESOLVE VERY

UNCERTAIN SHRTWV DETAILS OVER THE CONUS AT THE START OF THE PERIOD

AND TO YIELD THE DESIRED INTERMEDIATE TROF AXIS POSN OVER THE

CNTRL CONUS BY LATE IN THE WEEK. THIS SOLN ALSO MAINTAINS THE

INTEGRITY OF THE WRN NOAM RIDGE FAIRLY WELL THRU THE PERIOD.

...UPDATED MORNING PRELIMS..ADDITIONAL GUIDANCE OF 06Z GFS/06Z

GEFS MEAN/LAGGED AVERAGE FORECASTS/ENSEMBLE CLUSTER GROUPINGS

CONTINUE TO CONCUR WITH ABOVE THINKING. A DIFFICULT AND LOW TO NO

CONFIDENCE FORECAST IN DETAILS LATE PERIOD MAINLY WITH THE ERN

CONUS TROF. BASED ON AN AMALGAM OF DAYS 6-7 SOLUTIONS THE 06Z GFS

ENS MEAN SHOULD BE INCORPORATED INTO THE SOLUTION AND SUPPORTS THE

EARLIER ABOVE USED OVERNIGHT MODEL BLEND. DEPICTION BY DAY 5 FRI

OF A CENTER JUMPING SFC LOW FROM THE OH VALLEY TO THE NC COAST AND

THAN AN EXIT NEWD TO NEAR THE NEW ENG BENCH MARK BY DAY 6 SAT

SEEMS REASONABLE AT THIS TIME ALBEIT WITH CONTINUED VERY LOW

CONFIDENCE.

RAUSCH/ROSENSTEIN

5-6 day forecasts usually are which is why right now continuity forecasts and middle ground scenarios will rule the roost until this energy is fully sampled and completely integrated into the modeling.

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5-6 day forecasts usually are which is why right now continuity forecasts and middle ground scenarios will rule the roost until this energy is fully sampled and completely integrated into the modeling.

Exactly. I don't expect to see decent confidence at that range regarding any type of system let alone one that may produce snow.

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Here is the previous days link the storm is forecast to move along the classic track - nice looking set up- in February this is favored to be a snowstorm for I-95

http://www.hpc.ncep....ay5nav_pre.html

your putting way to much stock in these maps. They are for broad strokes this far out.

And while I don't think this cuts, I think I-95 should always be nervous when you dont have a classic greenland or davis strait block and 50/50 combo. Here we are relying on PNA amplification and a Polar high moving in at the right time.

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And they even mentioned the low confidence in the forecast. They have to make the maps, but sometimes the weenies need to realize just how uncertain they really are in the forecast and this is a classic example of it.

your putting way to much stock in these maps. They are for broad strokes this far out.

And while I don't think this cuts, I think I-95 should always be nervous when you dont have a classic greenland or davis strait block and 50/50 combo. Here we are relying on PNA amplification and a Polar high moving in at the right time.

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And they even mentioned the low confidence in the forecast. They have to make the maps, but sometimes the weenies need to realize just how uncertain they really are in the forecast and this is a classic example of it.

yup, i think everyone pretty much realizes how tough this is right now. No one should get hung up on any one solution, just watch the progression of the PNA ridge, the scandanavian block, and that lead energy which the euro turned into an inland runner last night before the deep trough set in.

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your putting way to much stock in these maps. They are for broad strokes this far out.

And while I don't think this cuts, I think I-95 should always be nervous when you dont have a classic greenland or davis strait block and 50/50 combo. Here we are relying on PNA amplification and a Polar high moving in at the right time.

I was just commenting on what would happen if that map verified- did I ever say this is going to verify ?

jUST BECAUSE SOMEONE MAKES COMMENTS ABOUT DIFFERENT FORECASTED MAPS OR MODELS DOESN'T MEAN THEY ENDORSE THEM .....

Also it kind of annoys me that you always try and find fault in someones post......

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dont like the look of the gfs so far. There is a lead vort prior to the pna spike which is meh and probably wont amount to much up here and then the energy which had been dropping into the middle of the country on other runs looks like its headed into the far sw which would most likely kill any chance at a bigger storm since it would cut off down there and rot.

Maybe it changes in the later frames.

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dont like the look of the gfs so far. There is a lead vort prior to the pna spike which is meh and probably wont amount to much up here and then the energy which had been dropping into the middle of the country on other runs looks like its headed into the far sw which would most likely kill any chance at a bigger storm since it would cut off down there and rot.

Maybe it changes in the later frames.

The 0z run had the lead shortwave very weak and shredded. The 12z run keeps it stronger through hour 96. We'll see what results.

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gfs trying to get the two streams back together now with the vort rotting over the sw ejecting some energy into the flow with a lot of moisture return of texas and a wide open gulf.

edit, never happens. Northern stream on its own. Could be a late developing MIller B, but it doesnt look great at all.

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gfs trying to get the two streams back together now with the vort rotting over the sw ejecting some energy into the flow with a lot of moisture return of texas and a wide open gulf.

It's still a cutoff low. If anything, the gfs is trying to produce a miller b storm with northern stream only.

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anything that comes from this is going to be later in the period here, sunday night and beyond

again, not gonna take any particular run too seriously at this point.

100% agree. Whether it shows a blizzard or rain and 50, model chaos right now.

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northern stream can't do it on its own here, the pna ridge is pushing things east and its not gonna bite. If we have some southern stream phasing, this type of run could work, but we get no help from that cutoff rotting.

oh well, another run, another solution.....patience.

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Models are converging to the vort cutting off in the SW though. That's pretty clear.

Yes but it is still a bit out there and as HM said last week, the models are really going to struggle with timing issues in the medium range. I personally thought any storm this weekend was a long shot snow wise. I was more interested in after the Super Bowl and beyond.

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northern stream can't do it on its own here, the pna ridge is pushing things east and its not gonna bite. If we have some southern stream phasing, this type of run could work, but we get no help from that cutoff rotting.

oh well, another run, another solution.....patience.

It's still trying to pop a miller b coastal for Saturday night.

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