UPDATE 7:00 AM 03/01/14
Let do a little comparison of the same model but 6 hours apart. You can clearly see the difference in the two runs.
Which would you prefer? A or B?
(Answer as a reply on this Facebook post)
A. 00Z (MIDNIGHT) GFS 03/01/14
OR
B. 06Z GFS (MOST RECENT) 03/01/14
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WINTER STORM WATCH IN EFFECT
(Accumulation amounts have been omitted from this text until things are more certain)
Winter Storm Watch in effect from Sunday evening through
Monday afternoon...
The National Weather Service in Mount Holly has issued a Winter
Storm Watch... which is in effect from Sunday evening through
Monday afternoon.
* Locations... southeastern Pennsylvania including Philadelphia
through central and coastal northern New Jersey.
* Hazard types... mostly snow and sleet.
* Timing... any rain that occurs Sunday afternoon should change to
sleet... or freezing rain for a short time before changing to all
snow late Sunday night. Snow will end Monday afternoon.
* Winds... north 5 to 15 mph with gusts up to 25 mph.
* Temperatures... falling through 20s late at night and to near 20
by noon Monday.
* Impacts... while there is still uncertainty regarding the amounts
of snow... sleet and freezing rain that will occur Sunday
night... there is little doubt that Monday morning will be snowy
and cold. This is projecting to be a high impact winter storm
for Monday morning.
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UPDATE 2:00 AM 03/01/14
0Z GFS ENSEMBLES
0Z UKMET
0Z EURO 03/01/14
These three models have shifted south a bit compared to maps posted on this blog earlier. Just goes to show how quickly or dramatically. The 18Z NAM (not posted) went south a great deal compared to 12Z posted below. earlier which was not posted was even further south. I know it seems confusing, but the best thing to look for is the most current models posted here.
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UPDATE 6:15 PM 02/28/14
Like clock work model waffling. GFS took a nose dive....south.
Typical model waffling. Not much to explain here. Ill be worried when other models show this as well.
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UPDATE 11:15 AM 02/28/14
12Z GFS hot off the press. Look familiar?
Still alot of yellow on that map for SEPA. Compared to previous runs, not as amped. High accumulations are supressed to a tighter area. Still in the 12"-16" range. One thing I want to point out with this run is that it appears a bit colder overall. You see that there isnt as much of a tight cut off on the snow accumulations to the south? Looks a lot like the 12Z NAM (below) and the 06Z GFS (further down).
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UPDATE 10:15 AM 02/28/14
NAM is out! It also shows a big snow storm for SEPA.
The 12Z NAM for today shows a massive dump of snow for SEPA. Its appears to be a tick south of the 06Z GFS pictured below in the 7:45 AM update. Although the NAM is in range, its best runs for this storm are the midnight run tonight or 6 AM run tomorrow. For now, the storm is here and we'll continue to watch for minor adjustments.
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UPDATE 7:45 AM 02/28/14
GFS still pounding our area. NAM to come shortly!
GFS 06Z 02/28/14 is STILL showing over 1" of liquid for SEPA. If you look even closer, you can see a pop here and there of 1.25" of liquid! Based only on a 10:1 ratio, that is 10" - 12" of snow. Keep in mind, this may start out as rain for the furthest southern portions of our viewing area. However, temps will drop fast during the storm. When you have dropping temperatures, you have rising ratios. Lets do the math on 15:1 ratios. 1.0" liquid x 15 ratio = 15" - - - - 1.25" liquid x 15 ratio = 18.75". These furmulations are for education purposes ONLY to show that the colder the temperature, the more snow you will see. With the incredible consistency that we've seen with most of the models so far, it is certain that there will be a storm.
This storm is has come on land in California and producing a much needed soaking for them. What does that mean for us? Models and meteorologists are now able to sample the actual storm itself to get a better understanding of it. That will give forecasters and models to start nailing down temperatures, exact paths. Mid-range models like the NAM (which only forecasts out to 84HRS) will start to show this storm. You will see us start to post this model later on tonight.
So, a few things we'll watch today:
-Temperatures (aloft and surface)
- Snow ratios
- Ice or mixing probabilities and amounts
Tonight and early tomorrow we'll start putting together a forecast for you.
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UPDATE 5:45 PM 02/27/14
GFS 18Z cranks out some consistency
Now that I've posted a few different maps on here, we can begin comparing and looking for consistencies, agreements or trends.
Comparing the 18Z to the 12Z GFS we will find that the placement of the cut off in snow fall is basically the same, situated along the Mason-Dixon line. The 18Z shows a much more elongated axis of higher snow amounts through central PA and into the Lehigh Valley and points north as compared to the 12Z.
Back to the cut off. The cut off represents the what is also the 32F for the majority of the storm. These maps only represent snowfall so areas to the south will still see a great deal of precipitation but mostly rain.
Lets compare the 18Z GFS to the 12Z EURO. The 18Z GFS appears to be in aggreement with the snow fall totals but the GFS is showing them up to 50 miles north of the EURO. This is what would be considered minor adjustments from model to model and run to run.
It is consistent through most of the models that there will be a significant storm in this time period and the consistency also says that this could be a 12" of snow or more for many in SEPA, particularly those to the north of approximately the PA Turnpike.
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UPDATE 3:30 PM 02/27/14
EURO 12Z 02/27/14 Total Snowfall
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UPDATE 11:30 AM 02/27/14
GFS 12Z 02/27/14 Total Snowfall
Showing 12"-14" of snow throughout SEPA. You see that sharp cutoff of amounts along the PA/MD boarder? That is where the freezing line will be for a majority of the storm. Still a lot of precip for south of that line, but will fall mostly as rain.
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UPDATE 10:45 AM 02/27/14
Reputable Sr. Forecaster Bernie Rayno at AccuWeather says right now it looks like a snow storm to the north and a ice storm to the south.
UPDATE 8:00 AM 02/27/2014
The storm is still here and is very much still a huge threat to SEPA. Lets get to it!
Disclaimer: This information is current data or graphics being shown for this storm and is NOT a official forecast. This is solely for the purpose of showing the progresison or evolution of this storm.
Canadian (CMC)
The 0Z (midnight) CMC (Canadian) model shows a long duration event or an overrunning event for us lasting up to 36+ hours. Draw a line through the middle of the region from east to west, say from Yardley (Bucks) to Lansdale (Montgomery) to just south of Reading (Berks). North of that line will remain all snow. South of that line will be all frozen but will change over to sleet or maybe even a change over to freezing rain. According to this particular model, plain rain doesnt make it further north than the Mason-Dixon line (PA/MD line).
This shows the area with the potential of ice (pink) mixture this is at the 111th hour from midnight today.
This shows 120th hour from midnight today. Hour 120 is the end of the CMC run. With that said Tonight or tomorrow we will be able to see the whole duration of this storm.
GFS
This is a text version of a map and is specifically for Wings Field, Whitpain Towsnhip, Montgomery County.
It shows that over all 1.14" of liquid (QPF) will fall. It says that there is a very small chance that it will start out as rain. It says that .48" of QPF (4.8" of snow) will fall before the possibility of changing over to sleet. It shows that .47" QPF of sleet will fall, which is quite significant and then a brief changeover to snow again.
EURO
Is still the warmest out of all models although still giving us a bit of snow. I will wait to see the 12z (noon) run before I say more about that.
NWS text updated 4:10 AM 02/27/14
AN IMPACTING WINTER WEATHER EVENT IS STILL EXPECTED TO AFFECT OUR FORECAST AREA FROM SUNDAY INTO MONDAY WITH A PROBABLE 24 HOUR CONCENTRATION CENTERED AROUND SUNDAY NIGHT AND MONDAY DAY. CONFIDENCE ABOUT PTYPE REMAINS LOW, BUT CONFIDENCE ABOUT AN EVENT AFFECTING OUR AREA REMAINS HIGHER THAN AVERAGE AT THIS TEMPORAL FCST JUNCTURE. THE TWO STRONGEST CIPS ANALOGS OFF THE 12Z GFS RUN BOTH HAD MIXED PCPN WINTER STORM CRITERIA EVENTS IN OUR CWA. WHILE
NOTHING IS EVER SET IN STONE THIS FAR OUT IN TIME, IT WOULD BE PRACTICAL FOR ANYONE INVOLVED WITH WINTER WEATHER MITIGATION TO USE THE NEXT SEVERAL DAYS TO GET PREPARED.
AS FAR AS THE MODELING IS GOING WITH THIS EVENT, THE OPERATION ECMWF REMAINS THE WARMEST, ALTHOUGH IT DID TREND SLIGHTLY COLDER FROM THE DAY RUN AND ITS ENSEMBLE MEAN IS SLIGHTLY COLDER BY MONDAY EVENING. ITS DIFFERENCE FROM THE OTHER MODELS IS A SLIGHTLY FARTHER NORTH PV IN EASTERN CANADA (LESS OF A NEARBY SFC RIDGE) AND HANGING BACK MORE ENERGY IN WESTERN CANADA. BOTH PERMIT A SLIGHTLY STRONGER TROF TO TRAVERSE THE CONUS AND BRING SLIGHTLY WARMER AIR INTO OUR CWA. THE GFS ENSEMBLE CLUSTERING HAS ABOUT A 40 PERCENT SUPPORT OF THIS WARMER SOLUTION. THE ECMWF HAS DONE A PRETTY CONSISTENT JOB OF "LOCKING IN" AT ABOUT 96 HOURS AND INWARD THIS WINTER. THIS WILL MAKE TODAY`S 12Z RUN ONE TO WATCH TO SEE THERMALLY WHO BLINKS FIRST.
More to come throughout the day!
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UPDATE 2:45 AM 02/26/2014
0Z ECMWF (EURO) was just released and it is showing this little graphic.
This shows total snowfall up to the 138th hour which would be 6PM on 03/04/2014.
The next frame is 138th hour to the 150th hour.
These two time frames combined give areas to the north and west of Philadelphia 12"+ of snow. Still a long way from being a solid forecast. However, a storm this big being shown now certainly deserves the attention this far out. Lets see how this progresses.
Check back with "Southeastern PA Severe Weather" on Facebook for updates and links to updated content on this site.
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We are tracking the potential for a snowstorm during the time of Monday March 3/4, 2014.
As a reference ONLY at this time, here is the bufkit warehouse readout of the KRDG (Reading, Berks County) GFS 00Z 02/26/14 run.
What this is showing is that starting 9AM 03/02/14, precipitation will start. Note that temperatures will be hugging the 32F degree mark +/- 1F degree. It shows that precipitation will end 9PM on 03/04/14 and will result in a total QPF of 1.54" of which .61" will be freezing rain accumulation, .7" of snow accumulation, .2" of sleet and about .5" of rain. This of course this 5 days away and things will likely change a few times. But one thing for certain is that a few models show this threat and possibility, based on outputs like these that there is a icing potential for a majority of the area.
