AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 1January 22, 2008

EFFECT OF TAMDAR ON RUC SHORT-TERM FORECASTS OF AVIATION-IMPACT FIELDS

FOR CEILING, VISIBILITY, REFLECTIVITY AND PRECIPITATION

Ed Szoke*, Stan Benjamin, Randy Collander*, Brian Jamison*,

Bill Moninger, Tom Schlatter**, Barry Schwartz and Tracy Smith*

NOAA/Earth Systems Research Laboratory

Global Systems Division

*Joint collaboration with the Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO**Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, Colorado

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 2January 22, 2008

Overview

TAMDAR soundings have been shown to be useful for forecasting Talks at the last SLS Conference and previous Annual Meetings WFO Green Bay helps maintain the official NOAA TAMDAR web page

at http://www.crh.noaa.gov/tamdar/ In this talk we focus on the impact of TAMDAR on short-term NWP:

Evaluation of RUC precipitation and visibility/ceiling short-term forecasts for runs with and without TAMDAR

No reflectivity comparisons yet; these are coming.... Mostly a subjective evaluation, but objective scoring for 2007 cases

Procedure: RUC is run at 20-km horizontal grid resolution Identical runs made hourly to 6 h, and out to 24 h every 3 h Here we will concentrate on shorter term (usually first 6 h to 12 h)

forecasts initialized when TAMDAR data is most plentiful 1800 UTC and 0000 UTC initialization times generally used

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Flights into a numberof smaller airportsin addition to the 3 main hubs

And at lower altitudes (generallyto 20 kft or so)

Typical TAMDAR coverage (shown here 1000 UTC/14 Jan – 0400 UTC/15 Jan 08)

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Verification areas.Objective scoring isdone on both areas,for this study we will show some scoresfor the inner (blue) box .

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Still one of the most dramatic cases...4-5 Oct2005: heavy precip in the Upper Midwest.

Flooding reported inMinnesota to northernWisconsin.

Case 1: 4 October 2005 – 2100 UTC Surface analyses and reflectivity

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Very sharp cut off to theprecip in WIand a huge gradient witha 2-3” max.

NPVU estimated precipitation for 6-h ending 0000 UTC 5 October 2005

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 7January 22, 2008

Both runs forecast too much precip in southern half of Wisconsin, but the RUC run withTAMDAR correctly forecasts more precip (small spots of >1.00”) across the northern half of the state.

RUC forecasts from the 4 October 2005 1800 UTC runs 6-h total precipitation ending 0000 UTC 5 October

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 8January 22, 2008

Sounding comparison: RUC 6-h forecasts with (labeled dev2) and without(labeled dev1, in black) TAMDAR, compared to the RAOB for Detroit (green)at 0000 UTC 5 Oct 05. Incorrect dry layer in the dev1 forecast.

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 9January 22, 2008

Same comparison but for Peoria, Illinois. The RUC run with TAMDAR is closer to the RAOB especially at and below 700 mb.

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 10January 22, 2008

Heavy precip continuesin the same areas

Case 1/part 2: 5 October 2005 – 0300 UTC Surface analyses and reflectivity

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NPVU estimated precipitation for 6-h ending 0600 UTC 5 October 2005

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For this period the RUC run that used the TAMDAR data is a much better forecast with a very sharp cut off to the precipitation in Wisconsin and a better location for the heavyprecip.

RUC forecasts from the 5 October 2005 0000 UTC runs 6-h total precipitation ending 0600 UTC 5 October

No TAMDAR With TAMDAR

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Case 2: 7 December 2007 – 1200 UTC 500 mb obs and analysis

Area of interest: KY/TN

Very weak short-wave trough

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Case 2: 8 December 2007 0000 UTC 850 mb obs and analysis

Area of interest: KY/TN

Overrunning situation in place.

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Case 2: 7 December 2007 – 1800 UTC Surface obs and reflectivity

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Case 2: 7 December 2007 – 2100 UTC Surface obs and reflectivity

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Case 2: 8 December 2007 – 0000 UTC Surface obs and reflectivity

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NPVU estimated precipitation for 6-h ending 0000 UTC 8 December 2007

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3-h accumulated precip forecasts from the 1800 UTC 7 Dec 2007 RUC runs:Without TAMAR With TAMAR

3-h valid at 2100 UTC

6-h valid at 0000 UTC

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 20January 22, 2008

Sounding comparison between RUC 6-h forecast with (labeled dev2) and without (labeled dev, in black) TAMDAR, compared to the RAOB for Nashville (BNA) for 0000 UTC 8 Dec 07. dev2 is closer to the observed sounding, while dev is too dry, similar to the forecast from the RUC run without TAMDAR.

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 21January 22, 2008

Did the TAMDAR data lead to a better forecast? Here is a comparison between the two 1800 UTC RUC analysis soundings at Memphis (MEM) compared to some nearby TAMDAR soundings.

Note how the analysis from dev2 (RUC withTAMDAR) is more moist thanthe dev analysis,and comparesbetter to the TAMDAR data.

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 22January 22, 2008

The SPC severe reports show numerous tornadoes, with some into Southeast Wisconsin (pictures courtesy of Milwaukee/Sullivan, WI WFO).

Case 3 - 7-8 January 2008: Unusual January tornado outbreak in the Midwestfollowed by rain/snow the next day.

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This was a strong system with a deep approaching trough at 500 mb.

Case 3 - 500 mb analysis and plot for 0000 UTC 8 January 2008

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Case 3: 7 January 2008 – 1800 UTC Surface analyses and reflectivity

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Case 3: 7 January 2008 – 2100 UTC Surface analyses and reflectivity

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Case 3: 8 January 2008 – 0000 UTC Surface analyses and reflectivity

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NPVU estimated precipitation for 6-h ending 0000 UTC 8 January 2008

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Mixed verification: The RUC run with TAMDAR verifies better in northern Illinois (blue circle), but not as good as the run without TAMDAR in northern Wisconsin (red circle).

RUC forecasts from the 8 January 2008 1800 UTC runs 6-h total precipitation ending 0000 UTC 9 January

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Case 4: 10 January 2008 – 1800 UTC Surface & 500 mb analyses and reflectivity2 days after the tornadoes....a modest snowstorm hits the Midwest, with more severe weather south to the Gulf coast

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Case 4: 10 January 2008 – Watches and warnings/advisories as of 2200 UTC

Prompting the hoisting of WinterWeather Advisoriesfrom Iowa to Wisconsin

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Case 4: comparison of 18-h accumulated precip forecasts from the 1800 UTC 10 Jan 08 runs

In this case we can compare the18-h accumulated precipitation forecasts to the NPVU 24-h estimate for portions of the Midwest as the precip fell after 1800 UTC 10 Jan. The RUC runwith TAMDAR has more precip in Wisconsin, which verifies better.

RUC without TAMDAR

RUC with TAMDAR

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 32January 22, 2008

Case 4: comparison of 18-h accumulated precip forecasts from the 1800 UTC 10 Jan 08 runs

Here is the comparison of the18-h accumulated snowfall forecasts to the 24-h snow reports. A forecast of more snow in Wisconsin is better.

RUC without TAMDAR

RUC with TAMDAR

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Case 5: 21 December 2007 – the Midwest in a pre-Christmas fog. 21z with vis image.

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White shading is for a forecast of visibility at or below 1 mileSome differences are seen – these are outlined in the forecasts; similar differences were found in the 6-h forecasts valid at 0000 UTC. Verification: The RUC forecast that uses TAMDAR is better along the WI/MN borderbut worse in WI, where more dense fog is a better forecast.

RUC 3-h forecasts of visibility from the 21 December 2007 1800 UTC runs valid 2100 UTC 21 December

Without TAMDAR With TAMDAR

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Case 5: 21 December 2007 – WI/MN/IA closeup for 2100 UTC.

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TAMDAR coverage for the period 1500to 1800 UTC on 21 December 2007

One reason for less improvement with the TAMDAR run might have beenbecause of flights canceled by the fog.

TAMDAR coverage for the period 1500to 1800 UTC on 7 December 2007 when conditions were better.

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Case 6: 8 January 2008 – more Midwest fog; 0600 UTC cig and vis plot from AWIPS.

Visibilities undera mile coverpretty much all of Wisconsin

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 38January 22, 2008

White shading is for a forecast of visibility below 1 mileMain differences are found in eastern Wisconsin Verification: The RUC forecast that uses TAMDAR is better in eastern WI where more fog is the better forecast.

RUC 6-h forecasts of visibility from the 8 January 2008 0000 UTC runs valid 0600 UTC 8 January

Without TAMDAR With TAMDAR

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 39January 22, 2008

Only small differences between the forecasts, in southern Wisconsin. Often many cases had just small differences between the RUC forecasts. Verification: There is nothing in the observations to support the sliver of higher CIGS found in the forecast without TAMDAR

RUC 6-h forecasts of ceiling from the 8 January 2008 0000 UTC runs valid 0600 UTC 8 January

Without TAMDAR With TAMDAR

ceiling height AGL x1000 feet

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 40January 22, 2008

Statistics (CSI) for the period 20 Nov 2007 – 15 Jan 2008 for LIFR conditions (vis < 1 mile and/or cig < 500 ft AGL) from the 1800 UTC runs.

6-h forecasts from the 1800 RUC runs with (“dev2”) and without (“dev”) TAMDAR. Difference plot is positive when dev2 is better than dev.Yellow vertical line denotes case day shown earlier.

No real trend for better performance with TAMDAR for this period and forecast cycle.

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 41January 22, 2008

Statistics (CSI) for the period 20 Nov 2007 – 15 Jan 2008 for LIFR conditions (vis < 1 mile and/or cig < 500 ft AGL) from the 0000 UTC runs.

6-h forecasts from the 0000 RUC runs with (“dev2”) and without (“dev”) TAMDAR. Difference plot is positive when dev2 is better than dev.Yellow vertical line denotes case day shown earlier.

Again, no real trend for better performance with TAMDAR for this period and forecast cycle.

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EQTS numbers that favor the RUC run that uses TAMDAR are highlighted in red. Most scores are closeor slightly favor the run with TAMDAR, especially the6-h forecasts from the 1800 UTC runs.

Objective scores for the two RUC forecasts for the small verification area

AMS 13th Conference on Aviation, Range and Aerospace Meteorology – January 2008 – New Orleans, Louisiana 43January 22, 2008

Summary

One of the earliest precipitation forecasts examined (the 4-5 October 2005 case) remains the most impressive one we've seen in terms of significantly better forecasts by the RUC run that used TAMDAR

More typically, we see much smaller impacts These tend to favor the RUC run that uses TAMDAR, but not

always And sometimes mixed...forecast better in some spots but not in

others Objective scoring of the precipitation forecasts that began in 2007

agrees with our overall subjective impression But on a case by case basis can see differences in the scores

Ceiling and visibility forecasts generally behave like what we have seen with precipitation Usually mixed verification...sometimes within the same forecast

time.