Daweathablog

Charles E. Roop giving his own forecasts, weather discussions, photos and adventures for the Starkville, MS area, Florida, and beyond.

Sunday, March 28, 2010

Watching the Gulf of Mexico

Good morning! Things have changed slightly since last night's weather post. From viewing satellite imagery, HPC surface observations and discussions, a warm frontal boundary in the eastern Gulf of Mexico has formed and, therefore, spawned some showers and likely thunderstorms (judging by the cold cloudtops on infrared sat imagery). Some views of this cluster can be seen on composite radar, but I am not taking too much credence of the reflectivity values just yet due to the distances of the coldest cloudtops (on the west side of the complex) from the NEXRAD sites.

Overcast conditions have now taken over Gainesville and will likely continue as this cluster of storms moves east.


Images: IR satellite (left, via WeatherTap.com); Surface MSLP/wind (right, via NOAA/SPC)

This cloudcover may take down the instability a notch because of the lack of daytime heating. Dewpoints in GNV has yet to reach 60 while places such as Ocala and southward have hit or surpassed that mark.

Rain should start affecting the area later on today. However, expect another batch of rain and storms later on tonight as the front nears and dynamics improve.

More later.

Saturday, March 27, 2010

Slight Severe Weather Threat Sunday

Good (late) evening, everyone. It's been a while since my last weather post. Schoolwork and the lack of any blog-worthy interesting weather has kept me from writing. However, there looks to be a good reason this time.

I checked out the forecast this morning and noticed a good chance of rain in the forecast as a storm system from the west is expected to approach the area. Later in the afternoon, the Storm Prediction Center issued an update. They raised the severe threat from, well, nothing to slight risk...

...FL PENINSULA...
MULTI-EPISODE/MAJORITY OF THE PERIOD SEVERE POTENTIAL WILL LIKELY EXIST ACROSS THE FL PENINSULA...AND REGION APPEARS TO WARRANT A CATEGORICAL SLIGHT RISK. SEVERE THREAT MAY INITIALLY INCREASE DURING THE AFTERNOON...EITHER VIA INLAND ADVANCEMENT OR PERIPHERAL DEVELOPMENT OF EARLY DAY GULF OF MEXICO TSTMS. THIS MAY ESPECIALLY BE ACROSS THE NORTH CENTRAL FL PENINSULA AMIDST AN INCREASINGLY MOIST/WEAKLY CAPPED BOUNDARY LAYER...WHERE VERTICAL SHEAR PROFILES WOULD SUPPORT SOME SUPERCELLS.

ADDITIONALLY...AS AN UPSTREAM SHORTWAVE TROUGH CROSSES THE GULF COAST AND THE POLAR/SUBTROPICAL JETS COME INTO PHASE SUNDAY NIGHT...STRENGTHENING DEEP LAYER SHEAR /WHILE A CONTINUALLY MOISTENING BOUNDARY LAYER/ AMIDST A STRONGLY DIFFLUENT REGIME COULD ALSO SUPPORT A NOCTURNAL RISK FOR SOME SUPERCELLS/BOWS WITH A DAMAGING WIND/TORNADO RISK.

So, basically we have the following: increasing southerly flow to bring in moisture (with models pointing at dewpoints in the 60s), weak cap to support continuous lifting, and wind shear looking susceptible to some supercell development.


NAM models: 250-mb wind forecast for 8 pm ET Sunday (right) and Temp/Dewpoint forecast for 5 pm ET.
Source: MeteoStar


After dark, things will deteriorate more as guidance models move a squall line into the north Florida area around 8 p.m. ET. The GFS seems to be more aggressive with heavy activity around this time compared to the NAM where more seems to build to the south of Gainesville later at night. The polar jet stream, along with the El Nino-enhanced subtropical jet, will aid in enhancing precipitation along with a "damaging wind/tornado risk."

We shall see what happens. Stay tuned.