All Weather News

Weather Update, November 4, 2008: Snow Event!

4 Nov 2008, 1:37 pm

It is fun to see my forecast from last Thursday slowly start to come together, as the various National Weather Service Offices have begun issuing watches and warnings for the developing storms. Below is a screen cap of our HAMrad II Precipitation Type Radar in action, clearly depicting snowfall this morning in higher elevations. Compare to a snapshot of our HWwarnings from this morning at left.
Sampling of Watches and Warnings active the morning of November 4, 2008
Colorado Winter Storm Warning
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
451 AM MST TUE NOV 4 2008

A WINTER STORM WARNING REMAINS IN EFFECT FROM NOON TODAY TO 3 AM MST THURSDAY.

A STRONG WINTER STORM WILL BRING 8 TO 14 INCHES OF SNOW… WITH LOCALLY HIGHER AMOUNTS POSSIBLE…TO THE ELKHEAD…PARK…GORE AND ELK RANGES AS WELL AS THE FLAT TOPS. EXPECT SOUTHWEST WINDS TO INCREASE TO 15 TO 25 MPH WITH GUSTS TO 35 MPH CREATING WIDESPREAD AREAS OF BLOWING AND DRIFTING SNOW. WINDS WILL SHIFT TO THE WEST AND DECREASE WEDNESDAY NIGHT.

North and South Dakota Winter Storm Watch
NATIONAL WEATHER SERVICE BISMARCK ND
307 AM CST TUE NOV 4 2008

A MAJOR STORM SYSTEM FOR NORTH DAKOTA…

A POWERFUL STORM SYSTEM WILL BRING THE THREAT OF VERY HEAVY WET SNOW AND HIGH WINDS TO WESTERN AND CENTRAL NORTH DAKOTA WEDNESDAY EVENING THROUGH THURSDAY NIGHT. THE PRECIPITATION WILL BEGIN AS RAIN TONIGHT ACROSS MUCH OF THE REGION. SOME THUNDERSTORMS MAY EVEN DEVELOP. THEN AS COLD AIR FEEDS INTO THE SYSTEM…THE RAIN WILL CHANGE TO SNOW.

FIRST…IN THE NORTHWEST PART OF THE STATE WEDNESDAY AFTERNOON. THE CHANGE OVER TO SNOW WILL THEN PROGRESS SOUTHEASTWARD REACHING BISMARCK THURSDAY MORNING AND JAMESTOWN THURSDAY AFTERNOON. A PERIOD OF FREEZING RAIN MAY ACCOMPANY THE CHANGE TO SNOW. AT THIS TIME IT APPEARS THE THE HEAVIEST SNOW WILL LIE ALONG A NORTH SOUTH LINE BETWEEN DICKINSON AND BISMARCK.

SIX OR MORE INCHES OF SNOW ARE POSSIBLE OVER THE WESTERN AND CENTRAL PARTS OF THE STATE. STRONG NORTH WINDS WILL GUST OVER 45 MPH CREATING POSSIBLE NEAR BLIZZARD CONDITIONS THURSDAY.

THE PUBLIC IS URGED BE PREPARED FOR THIS STORM. RECONSIDER YOUR TRAVEL PLANS AND FREQUENTLY CHECK THE LATEST CONDITIONS… STATEMENTS AND FORECASTS FROM YOUR NATIONAL WEATHER SERVICE.

Current Model Thoughts

So what are the models saying today? First, notice above that the winter storm watch issued covers basically what NAM was saying yesterday. However has that changed (note below)?

NAM 84 Hour Forecast Snowdepth Animation Product (3 hour intervals)

Recall from yesterday’s post that NAM covered the general area that the winter storm watch is currently issued for, while GFS centered the area of highest predicted snowfall more towards the center of North Dakota.

However, today NAM is thinking that nearly all of North and South Dakota will see significant snowfall, as well as the Nebraska Panhandle and most of Northern Nebraska (including one of my favorite Nebraska cities Valentine, Nebraska, which has a fantastic Pizza Hut, and the Comfort Inn isn’t too bad either!). I have provided the last NAM forecast cycle for your convenience below which is valid through 00z Saturday. Notice the extended area of predicted snowfall (click for full size).

Static NAM 84 Hour Forecast Snowdepth Product valid 00z Saturday, November 8, 2008

So will adjustments have to be made for the winter storm watch and forthcoming warnings, or is everything ok as it is now? We shall soon see!

Another important issue is forecast temperatures, and the timing with atmospheric progression. Since we have been discussing NAM, let’s see what NAM has to say about temperatures for the remainder of the week. Below is an animation of two-meter temperatures in farenheit (2mt) out through 84 hours (00 sat), with the animation intervals in three hour increments.

NAM 84 Hour Two Meter Temperatures Animation (3 hour increments)

A few interesting things to notice. First is that we see our first below zero / negative temperatures for the year in the higher elevations of the Rocky Mountains. Second, is notice that I provide two colored “lines” of temperatures (32°F and 72°F isotherms) to aid in highlighting “temperatures of interest.” I provide the 72°F isotherm in the hopes that perhaps this year maybe i’ll take a vacation to somewhere warm, as I haven’t had a vacation in decades (plural tense); but more importantly, note the 32°F isotherm and the timing of cold air advection (‘horizontal’ movement of cooler air at the surface or aloft) in North Dakota and South Dakota. Could this movement affect the timing and location of snowfall?

For your convenience I have included the last forecast cycle (84 hours) below, valid 00z Saturday (Friday evening).

Static NAM 84 Hour Forecast Two Meter Temperatures valid 00z Saturday, November 8, 2008

This will definitely be an interesting event to watch. I’m still not excited about Invest 93L yet, as it seems content to meander around without any significant promise of development. If something of interest should occur I will let you know.

As always stay tuned to your favorite weather outlet, stay informed, and stay safe!

cheers,

–patrick

Leave a comment

Your email address will not be published. Required fields are marked *