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#504311 05/17/15 04:12 AM
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Marty Offline OP
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Onset of the Rainy Season

At this time folks are apprehensive about the start of the rains, especially farmers who must plant just before the rains set in.

Here is the Ten day Outlook.

It can serve as a guide to the start of the rains during this El Nino year. I will be monitoring the model outputs over the next ten days to see how the models are resolving the atmospheric circulation to summer conditions in the Caribbean and Central America. The winter pattern is already disappearing over North America, Gulf of Mexico and the Western Atlantic.

The GFS-mnsprd and GFS Climate Model Outlooks initiated at noon on Friday, May 15, 2015 for the western Caribbean and Belize were favoring the seasonal dry conditions to persist for the next eight to nine days.

Both models resolve a disturbed area of moisture and instability (low pressure) to move off the coast of Panama and Costa Rica after the next 48 to 72 hours. This instability center will intensify and increase in coverage as it drifts NNE towards eastern Jamaica. By the weekend of 23-24 May, this feature will weaken, but the broad area of moisture and instability will drift westwards towards the coast of Belize. The instability will reach Belize by late 24 May, resulting in moderate to heavy outbreaks of showers especially over the northern half of the country at first; then spreading over the rest of the country by 25 May. This could mark the start of the rains as the models have the instability and a low pressure system persisting over the region for several days.

Click here for the full 10-day Outlook for Belize by RFrutos, Meteorologist/Hydrologist


GFS 264 hr Model projections valid for 6:00 am, Wednesday, May 27, 2015, showing low pressure over Belize, and rain (0.5 - 1.00 inch/24 hrs) spreading over northern Belize.


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Marty Offline OP
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Here is the update for the Ten-day Weather Outlook.

Model projections are indicating an intensifying ENSO (Warm Event) in the eastern Pacific through the autumn of 2015. This is alarming as it could spell high variability in the rainy season rainfall pattern for Belize, similar to 1997.

The GFS-mnsprd and GFS Climate Model Outlooks initiated at noon on Friday, May 15, 2015 for the western Caribbean and Belize were favoring the seasonal dry conditions to persist for the next eight to nine days.

Both models resolve a disturbed area of moisture and instability (low pressure) to move off the coast of Panama and Costa Rica after the next 48 to 72 hours. This instability center will intensify and increase in coverage as it drifts NNE towards eastern Jamaica. By the weekend of 23-24 May, this feature will weaken, but the broad area of moisture and instability will drift westwards towards the coast of Belize. The instability will reach Belize by late 24 May, resulting in moderate to heavy outbreaks of showers especially over the northern half of the country at first; then spreading over the rest of the country by 25 May. This could mark the start of the rains as the models have the instability and a low pressure system persisting over the region for several days.

Click here for the full report!



Joined: Oct 1999
Posts: 84,397
Marty Offline OP
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Here is the update for the Belize Ten-day Weather Outlook.

An analysis of the 10-day GFS and GFS-MNSPRD models prediction indicate that a fairly strong subsidence inversion in the East - Northeast trade wind flow will support only isolated shallow convection across Belize during the rest of May and through most of the first week of June. Therefore, expect little in the form of significant rainfall over the next 8 to 9 days which could increase the moisture content of the soil.

The models are resolving an energetic, eastward-moving upper level shortwave trough over the central Gulf of Mexico and southern Mexico on June 4-5. This feature, along with low pressures over northern Central America will induce a marked increase in convection over Yucatan, Guatemala, Belize and western Honduras. Vigorous outbreaks of showers and thunderstorms will begin to move across SW Belize on Friday, June 5, then spreading across the rest of Belize through Saturday and Sunday June 6-7, 2015. This activity is expected to persist through most of the second week of June. The GFS 288-hr. precipitation forecast map (Figure 1 below), shows rainfall rate of 0.10-0.25 of-an-inch/24hr in SW Belize for the morning of Saturday, June 6, 2015. The daily rainfall rates will increase over the rest of the weekend through most of the following working week. This event will very likely mark the onset of the 2015 rainy season in Belize.

Click here for the full report!


GFS 288 hr Model projections valid for 6:00 am, Saturday, June 6, 2015, showing low pressure over Belize, and cumulative rainfall in the range of 0.10-0.25 inch/24 hrs) spreading from the SW over Belize.


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Ten day Weather Outlook for Belize: Sunday, May 31, 2015

The models are indicating that we will see the some rain duirng this working week.

The updated GFS & GFS-MNSPRD forecast models (6:00 am, May 31, 2015 run) are still resolving an upper level trough extending North - South across the central Gulf of Mexico moving eastwards over the next 72 - 120 hours. This upper level trough is expected to interact with an approaching tropical wave that will be in the extreme NW Caribbean within the next 72 hours (See Figure 1 - 3 below; Wed., June 3, 2015).

These features will bring moisture and instability over the NW Caribbean and Belize, resulting in widespread showers with thunderstorms this week. This activity will start as early as Monday and Tuesday of this week, with heavier precipitation on Tuesday night and Wednesday, especially over the northern half of the country and over the coast and sea. A low will move offshore Belize on Wednesday, and is forecast to gradually drift NW towards western Cuba by Friday morning. The low will continue NW as the upper level trough picks it up and steers the low towards the western Atlantic.

Some areas of central and northern Belize could receive 1.5 to 2 inches of rainfall with higher amounts locally along the coast and the central highlands. The activity will decrease later on Wednesday, but the persisting moisture and instability will result in more outbreaks of showers through Friday and Saturday, but decreasing on Sunday.

This event could evolve into the start of the rainy season for 2015 over Belize. Remember that during an El Nino year, rainfall over the Atlantic coast of northern Central America can be very variable, with a tendency for dry spells during the wet months.


Onset of the Rainy Season, 2015

Rainfall accumulation of half inch to one inch was recorded over southern and coastal Belize, and about half an inch in central and western regions on Saturday last (May 23, 2015). In northern districts, some areas also received about half inch. The instability generating the showers and thunderstorms was short-lived and died away by early Sunday. The models were expecting this rainfall event to be brief. So, we can conclude that this was not the onset of the rainy season 2015 as it did not meet the criteria.

The brief review, discussed in an earlier report, with regards the onset of the rainy season at Spanish Lookout and Belmopan during El Nino years, shows that rainfall behavior is variable, with a high tendency for false starts. There is a higher probability for the start of the rains to occur during the last dekad in May and the first dekad in June in the Spanish Lookout area, while around Belmopan, the onset of the rains is more probable during the second dekad in June in El Ni�o years.

Outlook

An analysis of the 10-day GFS and GFS-MNSPRD models prediction indicate that a fairly strong subsidence inversion in the East - Northeast trade wind flow will support only isolated shallow convection across Belize during the rest of May and through most of the first week of June. Therefore, expect little in the form of significant rainfall over the next 8 to 9 days which could increase the moisture content of the soil.

The models are resolving an energetic, eastward-moving upper level shortwave trough over the central Gulf of Mexico and southern Mexico on June 4-5. This feature, along with low pressures over northern Central America will induce a marked increase in convection over Yucatan, Guatemala, Belize and western Honduras. Vigorous outbreaks of showers and thunderstorms will begin to move across SW Belize on Friday, June 5, then spreading across the rest of Belize through Saturday and Sunday June 6-7, 2015. This activity is expected to persist through most of the second week of June. The GFS 288-hr. precipitation forecast map (Figure 1 below), shows rainfall rate of 0.10-0.25 of-an-inch/24hr in SW Belize for the morning of Saturday, June 6, 2015. The daily rainfall rates will increase over the rest of the weekend through most of the following working week.

This event will very likely mark the onset of the 2015 rainy season in Belize.

Click here for the full report!


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Marty Offline OP
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Ten day Weather Outlook for Belize: Sunday, June 7, 2015

Here is the ten-day outlook. Expect wet conditions this week, especially late Thursday through Friday and Saturday.

Local flash flood conditions likely in the hilly areas on Friday and Saturday.

Two tropical waves will cross Belize during the next ten-days. The first will reach the country this Wednesday morning, while the other tropical wave will approach the country on Friday. A low will evolved from the second tropical wave over Belize during Friday, and will then drift NNE over the weekend (See Figure 1 and Figure 2 below).

A short-wave upper level trough in the southern and eastern Gulf of Mexico will provide outflow for the convective activity associated with the first tropical wave crossing the country, then an upper level high over southern Mexico and the NW Caribbean will favor strong uplift and outflow for the convection associated with the approaching, second tropical wave late Thursday night and Friday of this week.

The GFS-MNSPRD global ensemble forecast model is resolving intense convective activity over coastal waters and the mainland of Belize and Yucatan this coming Thursday, Friday and early Saturday. The GFS model is also resolving an 850 mb vorticity maximum traversing coastal waters of Belize and extending into the Bay of Campeche on Friday, in 2 association with the surface disturbance in the extreme NW Caribbean and Belize.

Hence, expect increasing outbreaks of scattered showers and thunderstorms later on Monday through Wednesday, increasing in intensity late Thursday night and Friday. The models are resolving 24-hr rainfall rates in the range of 0.25 - 1.00 inch on Tuesday through Wednesday, especially over central areas and the coast, with local rates of near 1.50 - 2.00 inches in the elevated terrain. Expect rainfall rates of 0.50 inch - 2.00 inches on Friday through Saturday, with locally higher rates of 2.5 - 3.00 inches in hilly terrain. Farmers and folks in the hilly terrain of the Stann Creek, Cayo, and Toledo districts should remain vigilant for high probability of locally developing flash-flood conditions.

Weather conditions will continue seasonally unsettled over the coming weekend through Wednesday of next week. Daily rainfall rates will be in the range of 0.25 - 1.00 inch, especially over coastal districts and the hilly areas of central Belize. Soil moisture will be near field capacity by the end of the second rainfall event early next week.



Figure 1: NHC 48hr forecast surface map Valid for 6: 00 am, Wednesday, June 9, showing TW moving into Belize and Yucatan



Figure 2: NHC 72-hr forecast surface map valid for 6:00 am, Thursday, June 10, showing a second TW west of Jamaica, reaching Belize by Friday evening.

Click here for the full report!


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Ten day Weather Outlook for Belize: June 20, 2015

An upper level low in the Bay of Campeche and NW Yucatan will provide the uplift for increasing convective activity over southern Mexico and northern Central America over the next five to seven days. An approaching Tropical Wave (TW) around middle of the week, coupled with a surge in the easterly airflow over the Caribbean, will provide low level instability for increasing widespread convection over Belize this Wednesday through Saturday. Residual moisture will provide the fuel for more showery conditions persisting through the last three days of June, 2015. Figures 1 - 3 below are the NOAA forecast precipitation maps for June 24 - June 26, 2015. Maximum, daily rainfall rates will be in the range of 20 - 40 mm (0.80 - 1.60 inch) over northern Central America during this period, with higher rates in the elevated terrain later on Thursday through Friday (June 25-26). Cumulative rainfall by the end of the working week will favor flooding in low-lying areas and localized flashfloods in the hilly terrain.

Click here for the full report!


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July 1 - 10, 2015

The NHC is expecting no tropical cyclone formation during the next five days. Also, a moist, unstable air-mass with an associated low level jet (LLJ) will favor more outbreaks of showers and thunderstorms around Bze through Friday and during next week. The TRIMM remote sensing data indicate that rainfall across Belize was above normal in June, 2015.

A seasonally moist, easterly airflow associated with the leading edge on a persistent, low level jet across the Caribbean is enhancing some brief showers and thunderstorms over northern Central America and Belize. A tropical wave around 85 W this afternoon will reach Belize within the next 24 hours, favoring an increase in convection over most districts later on Thursday and Friday. Expect maximum rainfall rates in some areas in the order on 0.60 of-aninch (15 mm) for Wednesday and early Thursday and near 0.50- 1.00 inch later on Thursday and Friday.

A second tropical wave moving into the western Caribbean on Friday will dissipate as it moves closer to Yucatan and Belize. Convection will cease somewhat on Saturday.

Click here for the full report!


Joined: Oct 1999
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Marty Offline OP
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Ten day Weather Outlook for Belize: July 13-22, 2015

Two tropical waves will approach Belize over the next ten days. The first will make its entry late Tuesday, and the second will cross the country on Friday-Saturday of this week. An upper level trough in the western Caribbean will shift westwards over the next three days, favoring outbreaks of showers and thunderstorms on Thursday and Friday. Conditions will become more stable on Saturday through Sunday, but significantly unstable on Monday through Thursday of next week, associated with the slow-moving low pressure system forming in the extreme NW Caribbean and Belize.


The GFS-MNSPRD global ensemble forecast model and the GSF model indicate no intense and persistent rainfall event this week through the coming weekend. However, the Models are resolving an increase in convection and rainfall from Monday through Thursday of next week associated with a low level disturbance in the NW Caribbean and Belize. Rainfall rates will be in the range of 0.50 - 0.75 inch/day in central and southern areas.

Farmers can expect some good showers on Tuesday afternoon, on Thursday and Friday. It will be much drier over the weekend. Expect more showers with some thunderstorm outbreaks during most of the working week next week.

Click here for the full report!


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Ten day Weather Outlook for Belize: Sept 8-18, 2015

The Models are supporting a brief reprieved from the unseasonal dry conditions ravaging the region and Belize. A number of tropical waves are heading our way, while an upper level disturbance in the SE Gulf of Mexico is pulling some moisture into our region today and tomorrow. However, the influence of ENSO will continue to put the lid on any organized and intense rain-producing system on the Caribbean coast of northern Central America, at least for the next ten days. The intense ENSO event is forecast to persist through the rest of 2015 and early 2016.

An eastward moving tropical wave in the southern and central Gulf of Mexico is generating scattered convection over the Bay of Campeche, Yucatan and Belize. A westward moving tropical wave entering the NW Caribbean this morning (Map 1) will reach Belize on Wednesday morning, increasing the instability over our area. This will generate some refreshing and welcoming showers across the country, after an extended mid-summer drought conditions that ravaged the region through August and early September. Rainfall rates will be ranging from: 0.10 - 0.25 of-an-inch mostly over the sea and coast today through Wednesday, increasing to rates of 0.75 - 1.00 inch on Wednesday night through Thursday. Showers will decrease on Friday.

Expect increasing showers over all districts on Saturday through Tuesday of next week. Rainfall rates will be in the range of 0.75 - 1.00 inch, especially in southern coastal region and the hills of central Belize. A low pressure system developing over Belize and the NW Caribbean early next week will keep atmospheric conditions unstable and favorable for showers during most of the week.

Click here for the full report!


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Here is an outlook for the next 7-days. The forecast model is supporting the unsettled weather to continue through Friday, then resuming early on Monday with an intense arctic airmass incursion over the central and eastern USA and the Gulf of Mexico, generating sho wery weather along a frontal zone entering the NW Caribbean.

NWS GFS Model initiated at 0600 UTC November 16, 2015, indicate that the unsettled condition will persist through most of this working week. The upper level shearline will continue drifting eastwards over the next 36 hours, but a moist, unstable ENE'ly flow over the NW Caribbean will maintain showers and rainy weather across Belize through Friday. This will be enhanced by the southward migration of a frontal system over the southern Gulf of Mexico on Thursday, but this cold front will not reach Belize. The activity will diminish on Saturday and early Sunday, but heavy convective activity will spread across Belize on Sunday night through Monday once again as an intense arctic air-mass push down across the central and eastern USA and into the Gulf of Mexico, pushing an active cold front through Belize and into the NW Caribbean during Monday of next week. The cold air will persist through most of next week, favoring coastal rains.

//ambergriscaye.com/art4/WeatherOutlookNov162015.pdf for the full report!


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