March 25-27 Plains/MW/GL/OV Storm, Reality: Short Range [0-3 Days Out] Forecasts Options

[Juniorrr]

First thread
GFS has been showing a storm for a while now with wintry precip possible...

~ more southern and colder

18z

Hour 42


Hour 48


Hour 54


Hour 60


Hour 66




This post has been edited by Juniorrr: Mar 24 2011, 05:13 PM

[grace]

6z DGEX

[WeatherMonger]

Forbes doesn't talk about winter weather obviously, but his thoughts on a few of the days. Had the risks a bit further North in Previous mentions. Source

Dr. Greg Forbes
Fri Mar 25. A chance of isolated severe thunderstorms, especially overnight, in central and east OK, north-central and northeast TX, west AR, extreme southeast KS, extreme southwest MO.

Dr. Greg Forbes
Sat Mar 26. Bears watching as a possible severe thunderstorm and tornado outbreak in east OK, extreme southeast KS, south MO, AR, north and east LA, MS, west and north AL, west and middle TN, west KY, south IL.

[WeatherMonger]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
615 AM CDT TUE MAR 22 2011

LONG TERM...FRIDAY THROUGH MONDAY
CHILLY WEATHER WILL PREVAIL THROUGH THE EXTENDED...WITH TEMPS
EXPECTED TO DROP BACK BELOW NORMAL FOR THIS TIME OF YEAR. MODELS IN
FAIRLY GOOD AGREEMENT WITH ANOTHER UPPER WAVE TRACKING ACROSS THE
AREA ON FRIDAY...RESULTING IN AN OVERRUNNING PRECIP EVENT. FORECAST
SOUNDINGS ARE COLD ENOUGH TO SUPPORT A RAIN/SNOW MIX...ESPECIALLY
ALONG AND NORTH OF A CANTON TO BLOOMINGTON-NORMAL LINE...ALTHOUGH
WITH HIGHS REACHING THE UPPER 30S/LOWER 40S...NO ACCUMULATION IS
EXPECTED. PICTURE BECOMES A LITTLE MORE UNCLEAR OVER THE WEEKEND AS
MODELS CONTINUE TO STRUGGLE WITH PATTERN. DUE TO LARGE
DISCREPANCIES BETWEEN THE GFS AND ECMWF...WILL NOT MAKE ANY CHANGES
BEYOND FRIDAY...OPTING TO MAINTAIN A COOL/DRY FORECAST THROUGH
MONDAY.

[Gilbertfly]

Skilling nugget. . .

Eastbound weekend system raises the specter of wet late season snow

Another eastbound storm will have to be monitored late this week and over the coming weekend. It could bring sticking snow to the nation's Heartland--potentially reaching Chicago or area's close-by Saturday---particularly in the afternoon and at night. Details of the system aren't yet perfectly clear. But a series of computer models Monday hinted the system could bring a late season snow an area close to, if not including, the Chicago area.

[The Snowman]

Skilling nugget. . .

No... Not more snow...

This post has been edited by The Snowman: Mar 22 2011, 02:16 PM

[Juniorrr]

Hm ill take it... what a teaser.


This post has been edited by Juniorrr: Mar 22 2011, 03:21 PM

[Removed_Member_OHweather2_*]

As we move forward, the focus will shift towards a storm system expected to eject east out of the Rockies at the beginning of next week.

Above is the ECMWF model valid 8am EDT Monday morning. There are a few features I want to point you to on the upper level forecast, in the upper left corner.

The first feature is a large, blocking ridge of high pressure near Hudson Bay in Canada. This, along with higher heights over Greenland (which is just off the edge of the image) will pin feature number two, a “50/50 low” over southeastern Canada. This is going to flood much of the northern US with cold air from the Rockies east. Note how the 5000 foot above sea level freezing line (solid black line) is well south in the bottom right image. This sets the stage for feature number three and the “southern stream energy” to eject from the western US.

What determines how strong of a storm occurs, and where it tracks, depends on if feature three phases, or combines with the southern stream energy. The southern stream energy will be very slow to move east, and feature three is riding in on a strong Pacific jet (note the tightly packed height lines off the west coast in the upper left panel), however is running into a ridge. If feature number three has enough momentum to continue pushing east, it may phase with the southern stream energy and result in deepening of the storm as it moves towards the Ohio Valley. In addition, the lobe of energy sinking south over the Great Lakes above may combine with feature three and the southern stream energy to help with the phasing process.

The most aggressive model, at the moment, with phasing this storm is the Canadian model, or GGEM:

The GGEM is in the process of phasing the pieces of energy in the above image, valid for next Tuesday morning. Note how the model has a deepening area of low pressure over the lower Ohio Valley (upper right image) and how the storm is closed off at the upper levels. This results in a large area of precipitation breaking out from the east coast back into the central Plains, where the model is printing out a significant amount of snow over parts of NE, KS, IA, MO and into IL.

The ECMWF model is less aggressive in phasing this storm. Note how Tuesday morning the ECMWF model is weaker and farther southeast with the storm than the Canadian model. The model is still printing out some snow over parts of the mid-Mississippi Valley, but wouldn’t be as impressive as the Canadian model.

The ECMWF however, due to being less aggressive with phasing the storm, shows a storm track farther south, and waits to blow up the storm until it reaches the east coast. This would result in a major late season Nor’easter over the Mid Atlantic and New England, and a major snow storm for the big east coast cities.


The GFS model on the other hand is significantly less aggressive with this storm and shows little if any phasing. This results in a non-event, with only some light rain breaking out over the southern and flurries in the colder air farther north.

So, what gives? Which model is right?

Essentially at this point in time, the models have some slight disagreements at the upper levels, which results in significant differences in their handling of the storm. At this point in time it is nearly impossible to speculate which model is right with this storm, however we can draw a few conclusions:

1. If the southern stream energy phases with energy moving in from the north is critical. No phasing=no major storm, while strong phasing could result in a strong storm cutting as far north as the lower Great Lakes.
2. There is some disagreement among the models on the handling of the 50/50 low over southeast Canada. This may affect how far south the models bring the northern stream energy, which would affect how much phasing the models show.
3. Either way, with a strong 50/50 low being shown on most if not all models, any storm that occurs in this time frame will likely occur farther south than the ongoing storm, which would spread snow/ice farther south, possibly into parts of the upper OV, Mid Mississippi Valley, and potentially portions of the Mid Atlantic.
4. Any storm would affect the central US Monday-Tuesday, and the eastern US Tuesday-Wednesday.

[Juniorrr]

6z DGEX

wow that is showing a nice snowstorm tease for VA.. but i think that is showing both storms, second is around the 29th

[CentralIllinois]

Skilling nugget. . .

looks interesting...but I think it would take a significant snow to actually accumulate considering its been in the 70's in the midwest for the past week or so.

[Removed_Member_OHweather2_*]

looks interesting...but I think it would take a significant snow to actually accumulate considering its been in the 70's in the midwest for the past week or so.

You'd be surprised at how well wet snow can stick after warm weather, especially at night.

[jdrenken]

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD
0142Z WED MAR 23 2011


00Z NCEP MODEL PRODUCTION IS ON TIME..9 G-IV DROPSONDES WERE
AVAILABLE FOR 00Z NAM INGEST IN SUPPORT OF WSR

00Z NAM RAOB RECAP...
YAP/91413 - 10159
ITO/91285 - 10142
LWX/72403 - PURGED TEMPS/MOISTURE 613-577MB...WET BULB EFFECT
LIH/91165 - PURGED TEMPS/MOISTURE 844-826MB...WET BULB EFFECT


$$

SHIREY/SDM/NCO/NCEP

[ctrlohio59]

That DGEX took me from 5-6 inches to maybe 1-2

[Gilbertfly]

HPC. . .

Day 3. . .2 inch or greater. . .


Maps. . .

[jdrenken]

Gotta love it when the NCEP is having updating issues. Seems like I've been stuck at 93hr forever and a day.

[snowlover2]

Looks like on the GFS that I-70 through IL/IN/OH is the dividing line. Snow north, rain south and maybe a mix right along it.

[jdrenken]

Just for giggles, the FA states KS/MO are suppose to get a good snow during this period.

[ctrlohio59]

Can someone post a GFS snowfall map?

[ctrlohio59]

It does look like QPF isn't all that high though

I am most likely wrong though

[snowlover2]

Can someone post a GFS snowfall map?