Frontal Types – Winter Weather Advisory

First up we have a winter weather advisory in place from 7am this morning to 4am tomorrow.  The color shaded areas show the percent of chances for 4 inches of snow – the red is the greatest chance, yellow the least.  The area in red could see 4 to 7 inches of the white stuff.

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Frontal Types

Certain types of severe weather differ in association with different front types. Severe weather can occur with cold fronts, warm fronts, and drylines. In the case of a stationary front, the severe weather tends to be similar to that associated with a warm front. First, you need to determine the convergence along the front, moisture along and ahead of the front, the movement of the front, and the upper level winds.

Stronger convergence along a front will result in an increased potential for uplift. An example of strong convergence along a cold front would be winds from the southeast at 25 mph south of the front and north at 20 mph north of the front. The higher the dewpoints, the more moisture a front will have to lift. If moisture is lacking on both sides of the front, do not expect significant precipitation.

The movement of the front will help you determine how long the precipitation will last. Slower moving fronts are more prone to produce heavy persistent rain. The upper level winds determine how fast a supercell will move once it forms. Supercells tend to follow the mean 700 to 500 millibar wind flow and upon maturity will turn slightly to the right (about 30 degrees) of the mean 700 to 500 mb flow.

COLD FRONTS: Cold fronts tend to be the fastest movers compared to the other front types. This fast movement increases convergence along the front and results in faster storm movement, if storms do develop. The slope of a cold front is greater than that of the other frontal types. This results in convection that is more vertical (lifting associated with warm fronts has a large horizontal component). For severe weather to be associated with cold fronts, look for the following: high dewpoints ahead of the front (60 F or greater), strong upper level winds (300 mb wind greater than 120 knots), front movement between 10 and 20 mph, and convergence along the front. Storms tend to be strongest on the southwest edge of the frontal boundary due to a combination of the following: higher dewpoints, more convective instability, cap breaks there last, uninhibited inflow into storms, storms are generally more isolated and thus realize more convective energy.

WARM FRONTS: Severe weather generally occurs on the warm side of the warm front but is most favorable in the vicinity of the warm front boundary. This is due to the fact that the greatest directional wind shear is located along the warm front boundary. When storm chasing warm front convection, a good location would be to stay near the warm front boundary while at the same time being relatively close to the mid-latitude cyclone which connects to the warm front. As a general rule, severe weather is not as common along a warm front boundary as compared to out ahead of cold front boundaries for these reasons: A smaller frontal slope results in less frontal convergence, east of the Rockies convective instability (dry air in mid-levels) is not as well defined with warm fronts, convection tends to be more horizontally slanted, the temperature gradient from one side of the frontal boundary to the other is generally less in association with warm fronts.

DRYLINES: The higher the dewpoint gradient from one side of the dryline to the other is a good indication of dryline intensity. Critical point: No convergence along the dryline results in NO storms. Drylines are most common in the high plains in the Spring and early Summer. Certain factors must be in place for a dryline to produce severe convection. As mentioned, the most critical is convergence. This convergence can be intensified by a combination of the following: Strong upper level winds overriding the dryline (can produce dryline bulge), warm moisture rich air being advected directly toward the dryline boundary (i.e. 850 mb Southeast wind at 30 knots ahead of the dryline, West wind at 35 knots behind dryline), and a upper level trough. Severe storms in association with drylines tend to be classic or LP supercells. The shallowness of moist air ahead of the dryline boundary limits the amount of PW and moisture the storms can convect. The cap is critical to determining if a dryline will produce storms. If convergence is not strong enough, the cap (inversion above PBL) will prevent convection from occurring. Strong convergence will break the cap. Generally, drylines are most intense and significant when a mid-latitude cyclone over the High or Great Plains forces warm moist air from the Gulf and dry air from the high plains to advect over the top of the warm moist air.


Other front terminology includes:

 

  • Frontogenesis

    The formation of a front occurs when two adjacent air masses with different densities and temperatures meet and strengthen the discontinuity between the air masses. It occurs most frequently over continental land areas such as over the Eastern US when the air mass moves out over the ocean. It is the opposite of frontolysis.

  • Frontolysis

    The weakening or dissipation of a front occurs when two adjacent air masses lose contrasting properties such as the density and temperature. It is the opposite of frontogenesis.

  • Occluded Front

    The union of two fronts, formed as a cold front overtakes a warm front or quasi-stationary front refers to a cold front occlusion. When a warm front overtakes a cold front or quasi-stationary front the process is termed a warm front occlusion. These processes lead to the dissipation of the front in which there is no gradient in temperature and moisture.

  • Ridge

    An elongated area of relatively high pressure that is typically associated with a anti-cyclonic wind shift.

  • Stationary Front

    A front that has not moved appreciably from its previous analyzed position.

  • Trough (Trof)

    An elongated area of relatively low pressure that is typically associated with a cyclonic wind shift.


I recently began a new coffee cup design – I am thinking of giving these out for donations of $50 or more – they cost $25 with shipping for each.  They are 15oz limited edition cups with the Skywarn logo and the radar image of the May 31, 1998 derecho event in Michigan.  Let me know what you think.

 

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Sandy (Hudsonville)Barry in ZeelandMr. NegativeINDYAndy W Recent comment authors
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Sandy (Hudsonville)
Sandy (Hudsonville)

At times today it was snowing so hard we couldn’t see anything.

Sandy (Hudsonville)
Sandy (Hudsonville)

I see they are calling for 70 degrees on Thursday. 🙂

Rocky (Rockford)
Rocky (Rockford)

Wow an April snowstorm that is an over producer. Some places just north of here will end up with 10 plus inches of fresh snow!!!!!!!!!!!

Rocky (Rockford)
Rocky (Rockford)

We are still getting pounded with heavy SNOW! What a storm! We are heading for about 5 to 6 inches! The snowshoeing should be incredible around sunrise tomorrow morning! What a winter!

Slim

Still getting snow and now blowing snow here just NW of GR, Total snow on the ground here is at 4.1″ So this will be a record snow fall for April 14th

Rocky (Rockford)
Rocky (Rockford)

Who would have thought?

Andy W
Andy W

CPC ALL ABOVE AVERAGE TEMPS NOW TOO!! Rocky’s one day of winter is going to be over here in a few hours!!! Then it’s back to winter wishcasting in December for him!! See you in November!!

Rocky (Rockford)
Rocky (Rockford)

You mean we might actually some real golf weather! Temps in the 60 and 70’s without 30 to 40 mph winds?

Rocky (Rockford)
Rocky (Rockford)

What a storm, what a winter and another month of above normal snowfall! I have picked up 3.5 inches of snow and counting! The roads are horrendous and rural schools are in jeopardy of school closings on Monday! Who would have thought? Don’t worry though because Andy and mookie said we would only see about an inch of snow it would all be melted in a few hours!

Andy W
Andy W

Yawn, when are you going to head out slushshoeing in that slop outside?? Hope your slushshoes don’t get caught in the mud and mess below the one inch of slush that’s on top of it! Back to enjoying my relaxing TV day!! I enjoyed my time yesterday outside in normal sunny weather!

Andy W
Andy W

One inch or 8 inches like you predicted we would get the other day it will all be melted tomorrow! Then this 24 hour weather blip will be a distant memory!

Andy W
Andy W

Looks like some nice thunderstorms may be coming Thursday! That would be nice to get those morels popping up!!

Given strong inflow of moisture from the Gulf and we may see an abundance of thunderstorm activity Thursday afternoon and a few of the storms
could be strong and perhaps severe across the southern cwa.

Rocky (Rockford)
Rocky (Rockford)

How many times have I heard that hype over the years with no results?

Andy W
Andy W

Just like all the so called blizzards predicted over the years with zero results!

Barry in Zeeland
Barry in Zeeland

Tiger Woods! Wow!

Mark (East Lansing)
Mark (East Lansing)

Good for him. It’s been a long time coming.

Still all rain here and a lot of it too. Lightning on east and southeast part of the state.

Andy W
Andy W

What a Masters!! That was fantastic!! I might even watch the replay on channel 3 now! It was that good!! Then that will lead right into the Game of Thrones premier tonight!! Great lounging on the sofa and TV day today!!

Slim

I now have 2.5″ of snow on the ground here at my house the temperature is still at 33 so this is a very wet snow to say the least. Still getting moderate to almost heavy snow fall at this time. And it is still very windy as well.
Slim

Slim

The snow fall and wind have now picked up here, Getting moderate snow fall and a good amount of wind
Slim

Slim

MV on the coffee cups they might be a good idea but I would wait until donations are made before you order any of them.
Slim

Slim

Not sure how much snow as fallen (more has fallen then has accumulated) but here at my house there is now a solid one inch of snow cover. It is now on the grass, roofs, trees and now even on the road and sidewalk. With today’s snow fall Grand Rapids will go above average for the month of April. Today may set a new record for snow fall for April 14th (1.6″ is the record for today) and for the 2018/19 season we will have to see just how close Grand Rapids gets to 80.0″ As before today’s snow it… Read more »

Rocky (Rockford)
Rocky (Rockford)

Records all over the place today! Incredible!

INDY
INDY

Our ground is covered with snow out at thee YARDofBRICKS NE GR hello 80+ inches of snow for the season …INDY!

Rocky (Rockford)
Rocky (Rockford)

We have a conveyor belt of moderate to heavy snow coming at us all afternoon long! Rock n roll baby!!

Mark (East Lansing)
Mark (East Lansing)

All rain so far. Doing laundry, have a pot of stew simmering, and watching The Masters. I hope they can get in the final round before the weather arrives.

Slim

Hey I as making stew also’
Slim

Mark (East Lansing)
Mark (East Lansing)

It’s a good day for it.

Mr. Negative
Mr. Negative

A breezy, 81 degrees in Cleawater this morning.

Rocky (Rockford)
Rocky (Rockford)

Wish you were here it feels and looks like mid winter! Who would have thought? It is a great late winter day on West MI!

Sandy (Hudsonville)
Sandy (Hudsonville)

ENJOY IT!! HAVE A GREAT DAY.

INDY
INDY

I’m thinking even bigger weather news then the little snow we are getting is the temperatures for this time of year 34* degrees out at thee YARDofBRICKS NE GR feels like only 24* degrees with the wind that’s almost 30* degrees below normal crazzy for mid April standards I’m thinking Mookiees windows are closed today lol ….Stay warm INDY!

Rocky (Rockford)
Rocky (Rockford)

Mookie is hibernating and his warm weather hype and fantasies will be back on Monday! He is hopeless!

Slim

Indy the high for today so far officially at Grand Rapids is 37 if that holds until midnight that would make today the 3rd coldest April maximum in Grand Rapids recorded history the coldest is 32 in 1943 and in 2nd place is 36 in 1907. As for Mookie’s windows do not know where he/she lives so do not know if windows are open or not.
Slim

Andy W
Andy W

Ahhh yes, just got done with my morning workout, sitting back on the couch watching early live coverage of The Masters!! Got the shades drawn on the window, not even paying attention to what’s going on outside today!! Much rather relax and watch golf right now, then do something boring like cross country skiing or snowshoeing on green grass outside!! Gonna be a great indoor day after my nine holes at Moss Ridge yesterday!! 37 weeks in a row of golf and counting!

Rocky (Rockford)
Rocky (Rockford)

I may be snowshoeing by this evening! We are getting hammered with snow!!!

Andy W
Andy W

BOOOOORRRRRIIIINNNGG!!!! Enjoy this 24 hour blip in the weather, the rest of the week will be in the upper 50’s and mid-60’s!! BRING IT!!

https://forecast.weather.gov/MapClick.php?lat=42.9664&lon=-85.6719#.XLNYCRYpCEc

Slim

Had a light shower the temperature here at my house is now at 37 so kind of warm for any snow to stick (if any falls) the wind has picked up and is now out of the east at around 20 MPH so the wind chill is in the mid 20’s
Slim

Rocky (Rockford)
Rocky (Rockford)

You will be hammered shortly!

Rocky (Rockford)
Rocky (Rockford)
Rocky (Rockford)
Rocky (Rockford)

Get ready for record April snows! Today will be cold, breezy, snowy and incredible! The winter that never ends! What a great winter it has been!

Mark (East Lansing)
Mark (East Lansing)

The predicted snow/rain line moved north overnight for me. As of 10p, NWS was calling for 3″ for us here. Now, less than an inch.

No complaints from this guy.