NAMMA Forecast Discussion

Cerese Albers, FSUJuly 21, 2006

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THE EUMETSAT website is down and the NAMMA real-time mission monitor 15-min imagery is still unavailable, so please refer to the following link provided by the NHC to the Meteosat IR imagery for today’s discussion:http://www.ssd.noaa.gov/PS/TROP/DATA/RT/eatl-ir4-loop.html

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The most recent imagery from Meteosat July 21, 2006 (see external link)

The NAMMA Synoptic Domain

Surface Analysis for July 21, 2006

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ITCZ

Wave AWave A

Wave BWave B Wave CWave C

Wave DWave D

AEW’s to monitor in the Tropical N. Atlantic Domain

Streamlines & Isotachs at 850 hPa

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Wave AWave AWave DWave D

Cross-equatorial flow is coming up from the Southern Hemisphere and carrying moisture with it that is feeding the long band of convection that extends from southern W Africa toward the ITCZ. Also of note, the Low pressure that moved off of West Africa (took a northern track) is associated with Wave C and should be monitored. It has altered many features such as the SAL, local convection and winds and

conditions near Cape Verde.

Wave CWave CLLWave BWave B

200 hPa Streamlines & Isotachs

200 mb was also examined for development purposes, and upper level winds indicate a strong High Pressure influence over of west Africa. Also note the TEJ is still being halted at 10-20*W. In addition, this analysis shows the role the upper level winds are playing in

the amount of shear across the East Atlantic.5

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The Saharan Air Layer (SAL) Analysis

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Not a good day for studying the SAL HERE b/c not a lot of dust to study other than a little near Cape Verde.

If a mission could go out If a mission could go out here off of Morocco might be a here off of Morocco might be a better SAL case study for better SAL case study for today.today.

Saharan Air Layer (SAL) Strength

Mid-Level W.V. at 12Z

SAL strength at 15Z

The low pressure system has altered the flow in the area and we see that the SAL is not very strong right now. Mid-level WV indicates areas East of Cape Verde are moist.

(From UW-CIMSS website)

Water Vapor from Meteosat

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GFS Analysis 12Z Precipitable Water

Info for convective modules

Courtesy NOAA NOMADS

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Wind Shear in the Domain (12Z)150-300mb layer mean minus 700-925mb layer mean150-300mb layer mean minus 700-925mb layer mean

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Shear off the coast of West Africa is strong but changing and could inhibit cyclogenesis as the wave continues into the E Atlantic.

Courtesy UWISC CIMSS

Low-Mid Level winds from CIMSS

Mid-level winds show how strong the change in flow around Wave C is.

(SHOW GFS)

Sea Surface Temperatures

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Begin to see substantial SST increase near Senegal and warm equatorial waters along the southern portion of where the waves interact.

SST Anomaly as of 7-15-06

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AEW Tracking: Latest Hovmoller

We have seen a fairly persistent pattern as of late where even strong AEW’s

have fallen victim to the high shear and relatively cool

SSTs this time of year in the E. Atlantic. This latest wave

still has some unfavorable conditions to encounter, and

may succumb to the same fate.

(Aside: EPAC:Hurricane Daniel)

Wave passage- weak Anomalous Winds (N/S) Winds at Dakar, Senegal

This shows the passage of the last strong wave (Wave C) a few days ago but also indicates that the wave that just exited past Senegal (Wave D) is not that impressive in depth or magnitude. 15

850 hPa Streamlines & Isotachs

This model is showing a well-developed area of closed streamlines at 850hPa in the Eastern Atlantic resulting from Wave C and persists it over the forecast period. Navy NOGAPS and FSU MM5 take this wave and keep it strong for about two days out. See http://moe.met.fsu.edu/tcgengifs/ 19

Precipitation in the Area

Current GFS Convective Precip.

Courtesy NOAA NOMADS

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Locally at Sal Airport, Cape Verde• TODAY: Mostly Cloudy and Hazy• METAR:AAXX 21124 08594 11430 70914 10269 20236 40146 69901

70552 878// 333 58018 84616 86620– High: 80*F. – HAZEHAZE– Wind Speed/Direction: E at 16 mph– Visibility: 3 km <- Visibility: 3 km <- NOT OPTIMALNOT OPTIMAL

• Take-off conditions are: FAIR. Landing: Better w/ clear skies less wind• Overnight: Mostly Clear.

– Low of 77*F. – ESE wind at 8 mph overnight.

• Tomorrow: Scattered Clouds 80*F/77*F with ENE shifting to NE winds 15 mph.

• Flight conditions will be better for the DC-8 tomorrow.

• Take-off window to catch convection: Later this afternoon. • Suggested Instruments to Prep: Convective module instruments

aboard planes today that are flying (G4 and DC-8). 21

Praia and Dakar• Praia has a little more variability than Sal. The

forecast for tomorrow evening may include a thunderstorm or two, with overcast conditions in the evening. Typical Highs and Lows are ~80* and 77* and the winds tend to generally come from the same direction as they do in Sal.

• At Dakar, Senegal, chance of thunderstorms over the next few days. Hi’s: ~84*F, Lo’s: ~80*F

• Dakar is highly subject to wave passages and diurnal convection.

Keep an eye on the low pressure system off of W Africa, even though most models do not forecast development for it or the wave (Wave C) associated with it at this time. It is still strong even though it may encounter some unfavorable shear but that is decreasing and SSTs look capable of supporting it.The TEJ is being disrupted aloft between 10*W and 20*W, and at mid-levels we see the AEJ is really developing well. This is enhancing the development of the most recent AEW’s we’ve seen.The dust in the SAL is not very strong and today is not necessarily the best day for a SAL A convective module is suggested to study the band off of southern W Africa. Flight conditions for take-off are not optimal, but improvement is expected.

Runway 1: Heading 01/19, 3,272m (10,734ft), PCN 58/F/A/W/T, ICAO Cat. E, Aircraft size max: B747, Lighting: Approach CAT 1, PAPI Runway 2: Heading 07/25, 1,500m (4,921ft), PCN 58/F/A/W/T, ICAO Cat. C, Aircraft size max: B747, No Lighting.

Forecast: 22