Posted on 02/14/2003 2:15:54 PM PST by John H K
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 445 PM EST FRI FEB 14 2003
...SHORT TERM...TONIGHT AND SAT...
ROUND ONE OF THIS WEEKEND'S TWO PART WINTER STORM HITS TONIGHT THRU LATE SAT. ACROSS THE FAR N ZONES AND MOUNTAINS...TEMPS WILL BE COOL ENOUGH THRU THE PERIOD THAT ALL SNOW IS EXPECTED. IN THE N SHEN VALLEY...NORTHERN VIRGINIA...AND DC AND S BALT AREAS...TEMPS WILL BE WARM ENOUGH FOR A RAIN/SNOW MIX TONIGHT. MODEL SOUNDINGS SHOW THE POSSIBILITY OF A BRIEF MIX OF SLEET OR FREEZING RAIN BETWEEN DAWN AND 8 AM. MID MORNING SAT...THE PRECIP WILL CHANGE TO ALL SNOW. ACROSS THE CENTRAL SHENANDOAH VALLEY...THE FREDERICKSBURG AREA AND SOUTHERN MARYLAND...PRIMARILY RAIN IN EXPECTED WITH A MIX OF SLEET/SNOW/OR FREEZING RAIN POSSIBLE. THE PRECIPITATION WILL CHANGE OVER TO MAINLY SNOW SOMETIME SAT AFT FROM N TO S. SNOWFALL ACCUMULATIONS WILL BE HIGHEST IN THE N WHERE MAINLY SNOW IS EXPECTED AND LOWEST IN THE S WHERE A SIGNIFICANT PERIOD OF MIX WILL OCCUR. RANGE FOR BOTH PERIODS...2 TO 6 INCHES.
MMARGRAF
LONG TERM (SAT NITE-FRI)
ETA/GFS HAVE TRENDED STRONGER AND SLOWER WITH RESPECT TO THE UPPER TROF THAT WILL BE EJECTING FROM THE PLAINS INTO THE MID-ATL STATES. ETA CLOSES OFF A MID-LVL CENTER BY 06Z MON NEAR PITTSBURG WHILE GFS DOES NOT. PER QPFHSD WILL LEAN MORE TOWARD THE ETA GIVEN IT HAS SOME SUPPORT FROM UKMET AND CANADIAN.
OCASSIONAL -SN EARLY SAT NITE WILL BECOME HEAVIER AS THE NIGHT PROGRESSES AS WAA PATTERN STRENGHTENS IN RESPONSE TO APPROACHING UPPER TROF/HEIGHT FALLS. 12Z ETA SHOWING IMPRESSIVE WAA PATTERN ON SUN WITH STG H85 EASTERLY JET OF 50 KTS FEEDING ATL MOISTURE INTO AN ALREADY JUICY AIR MASS. FCST PW FIELDS ARE OVR 0.8 INS OVR MOST OF THE CWA WITH VALUES EXCEEDING 1.0 IN OVR THE FAR SOUTHERN COUNTIES. ATMOS FROM TOP TO BOTTOM SUPPORTS MOSTLY SNOW ENTIRE CWA. HOWEVER MODELS SOUNDINGS SHOW SOME SLEET COULD GET MIXED IN WITH THE SN BETWEEN 00Z SUN-06Z SUN OVR FAR SRN MD/SPOTSYLVANIA/CHO. ADDED IP TO THOSE AREAS TO MATCH UP WITH SURROUNDING WFOS.
TEMPS ON SUN WILL HOVER AROUND 20 DEGS MOST OF THE DAY WHICH WILL PROBABLY RESULT IN HIGHER THAN NORMAL SNOW TO LIQUID RATIOS. GIVEN STRONG UPSLOPE COMPONENT (H85 50-KT JET)...STRONG 700-500 OMEGAS IN THE SNOW GROWTH REGION AND FVRBL LFQ JET DYNAMICS OF A 100-KT JET SUGGEST HEAVY SNOWFALL RATES THROUGH MUCH OF THE DAY ON SUN. EXTENDED PRECIP A LITTLE BIT LONGER INTO MIDDAY MON AS PER SLOWER TREND IN THE MODELS. ETA GIVING ALMOST 2.0 INS OF LIQUID EQUIVALENT WITH GFS ALMOST HALF OF THAT. BY THE TIME EVERYTHING IS SAID AND DONE WE COULD BE LOOKING AT THE MOST SIG SNOW EVENT IN THE WASHINGTON AREA SINCE EARLY JAN 1996. 10 INS OF SNOW WILL BE A VERY...VERY CONSERVATIVE SNOW TOTAL FOR THE AREA.
REST OF THE EXTENDED...TRENDED TEMPS COLDER GIVEN EXPECTED SNOWPACK. NEXT CHANCE OF PRECIP LOOKS TO BE NEXT FRI. LONG WAYS OUT FROM NOW KEPT IT DRY FOR NOW.
ROSA
That's what they are comparing it to - 2 inches of rainfall equivalent is a lot of snow...
I'm in PA now, and we're gonna get it...
You should have seen it this summer; they actually found some old boat wrecks the level was so low. Really quite sad.
looks like we'll either get about 6" or, depending on the track, a couple feet.
weathermen > guys/gals that can be wrong 50% of the time and still get paid ...
We may have gotten one half inch.
ISTM that the more data the weathermen have to work with, the less accurate forecasts have become.
OK I'm exaggerating (about the grocery store)
Actually, forecasts have gradually, and continuously, been getting more and more accurate. This can be shown statistically.
However, the perception is otherwise for a variety of reasons:
1) People are ATTEMPTING longer range forecasts than they did 20-30 years ago. Forecasts are more wrong the longer you forecast out, thus creating the impression there is more error.
2) Crisis of rising expectations. Forecasts are VERY gradually getting better...for example, on average, National Hurricane Center track error is reduced by about 1% a year. The improvement is much slower than people's expectations, much slower than the rate technology is getting better, so people get frustrated.
3) Just blatant old-fogeyism....the standard "back in my day, things were better" business. Viewing the past through rose-colored glasses. There was a huge amount of blown forecasts in the 70s, 60s, 50s, 40s, etc.
They were forecasting major rain from mid day on. We got a little band of showers about 11 a.m., then just sprinkles, and by 4 o'clock the SUN was out.
I planned for today to get my car worked on in the p.m. since it would be raining anyway. Missed a gorgeous day outside - could have been riding my horse instead of sitting in the waiting room at the Ford place . . . sigh.
The duct tape, man. For God's sake, do not forget the duct tape.
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