« Back
NWS Peachtree City, Ga » Text Product » HUN Area Forecast Discussion


Printer-friendly Version
Current Version              Previous Versions:   1  2  3  4  5  6  7  8  9  

Area Forecast Discussion

302
FXUS64 KHUN 271145
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
645 AM CDT WED MAY 27 2015

.UPDATE...
FOR 12Z TAFS

&&

.SYNOPSIS...
/ISSUED 331 AM CDT WED MAY 27 2015/

AN ACTIVE WEATHER PATTERN WILL PREVAIL OVER THE NEXT SEVERAL DAYS AS
SEVERAL IMPULSES MOVE ACROSS PORTIONS OF THE CONUS. THE FIRST
SHORTWAVE TROUGH THAT WILL IMPACT THE TN VALLEY HAS INDUCED MCS
ACTIVITY OVER THE ARKLATEX REGION AND WILL BE THE PRIMARY FOCUS FOR
THUNDERSTORM ACTIVITY OVER THE TN VALLEY THIS AFTERNOON. THEN,
ANOTHER MID-LEVEL SHORTWAVE TROUGH CROSSING THE DESERT SOUTHWEST WILL
PROVIDE ANOTHER FOCUS FOR THUNDERSTORM ACTIVITY ON THURSDAY ACROSS
THE SUPERSATURATED SOUTHERN PLAINS.

SL.77

&&

.DISCUSSION...
/ISSUED 331 AM CDT WED MAY 27 2015/

THE WEAKLY AMPLIFIED SHORTWAVE TROUGH THAT IS MOVING ACROSS OK INTO
AR WILL MOVE ACROSS THE TN VALLEY LATER THIS AFTERNOON. MCS ACTIVITY
ASSOCIATED WITH THIS TROUGH IS ALREADY IMPACTING THE ARKLATEX REGION
WITH BLOW OFF CIRRUS CROSSING OVER NW AL THIS MORNING. ADDITIONAL LOW
CLOUDS ARE MOVING ACROSS THE TN VALLEY. HOWEVER, THINNING OF THESE
CLOUDS IS LIKELY BUT IS DIFFICULT TO DETERMINE WHERE THE GREATEST
BREAKING IN THE CLOUDS WILL TAKE PLACE. IF THESE CLOUDS DO BREAK,
THEN INSOLATION ALONG WITH ALREADY WARM SFC TEMPERATURES WILL MEAN
DESTABILIZATION OF THE ENVIRONMENT SHOULD OCCUR. CURRENT MODEL
FORECAST SOUNDINGS SHOW MUCAPES BTWN 1000-2000 J/KG WITH THE NAM
MODEL THE MOST BULLISH WITH INSTABILITY. WEAK WIND SHEAR AND
ANTECEDENT SOUTHERLY FLOW COMBINED WITH THE INSTABILITY THAT IS
FORECAST MEAN THAT STRONG TO MARGINALLY SEVERE STORMS ARE LIKELY THIS
AFTERNOON. THERE IS UNCERTAINTY AS TO WHERE THE GREATEST INSTABILITY
WILL BE LOCATED GIVEN THE CLOUD COVER QUESTION. HOWEVER, THERE ARE
SOME INDICATIONS THAT NE AL MAY HAVE GREATER INSTABILITY WHERE HIGH
CLOUDS MAY NOT ENCROACH AS QUICKLY AS AREAS FURTHER WEST. SO, HAVE
INTRODUCED A GRADIENT IN POPS WITH HIGHER POPS OVER THAT AREA.
INVERTED V SOUNDINGS IN THE LOW LEVELS AND GENERALLY WEAK FLOW POINT
TOWARDS THE POSSIBILITY OF WET MICROBURSTS. THUS, THE PRIMARY THREAT
WITH THESE STORMS WILL BE GUSTY TO DAMAGING WIND GUSTS AND A LESSER
THREAT FOR SMALL HAIL. ONE LAST THING TO NOTE FOR TODAY`S FORECAST IS
THAT THERE MAY BE CONVECTIVE INDUCED MESOSCALE CONVECTIVE VORTICES
THAT MAY ACT TO ENHANCE REAR INFLOW JETS, PRODUCING HIGHER WIND GUSTS
ALONG ANY BOWING SEGMENTS.

AN ADDITIONAL SHORTWAVE TROUGH IS EXPECTED TO MOVE FROM THE SOUTHERN
PLAINS TOWARDS S MO/AR. AS IT DOES SO, IT WILL BE FURTHER REMOVED
FROM THE TN VALLEY (TO THE NW) WHICH WILL ACT TO LESSEN THE THREAT
FOR THUNDERSTORMS ON THURSDAY AFTERNOON/EVENING. THERE IS WEAK
INSTABILITY ON THURSDAY AFTERNOON WHICH WILL MAINLY TRANSLATE TO
ORDINARY THUNDERSTORMS ENDING LATE ON THURSDAY EVENING. MEANWHILE,
SHORTWAVE RIDGING WILL SPREAD NORTHWARD FROM THE GULF COAST. AS A
RESULT, BY FRIDAY, MORE ISOLATED TO SCATTERED THUNDERSTORMS WILL
PREVAIL DUE TO LACK OF LARGE SCALE LIFTING MECHANISM AND SUBSIDENCE.
IN ADDITION, DAYTIME HIGH TEMPERATURES SHOULD ALSO RISE INTO THE MID
80S (CLOSE TO NORMAL).

THEN, A CANADIAN UPPER LOW MOVING ALONG THE PREVAILING WESTERLIES OF
THE POLAR JET WILL EJECT A SHEARED TROUGH ACROSS THE N PLAINS, UPPER
MIDWEST, AND GREAT PLAINS ON FRIDAY INTO SATURDAY. A SFC COLD FRONT
WILL MOVE AHEAD OF THIS TROUGH AND ACT AS THE FOCUSING MECHANISM FOR
SHOWERS AND THUNDERSTORMS ACROSS THE OH AND MS RIVER VALLEYS. AS IT
SLOWLY PROGRESSES SOUTHEAST, IT IS EXPECTED TO BE THE FOCUSING
MECHANISM FOR DEEP CONVECTIVE UPDRAFTS OVER THE TN VALLEY ON SUNDAY
AFTERNOON. AS THE FRONT APPROACHES, IT LOOKS TO BECOME ILL-DEFINED OR
DISSIPATES ON MONDAY (TYPICAL FOR THIS TIME OF YEAR) BUT WILL STILL
KEEP CHC POPS IN THE FORECAST FOR THAT PERIOD. THE MID-UPPER FLOW
PATTERN THEN SHIFTS TO A SHORTWAVE TROUGH MEANDERING AROUND THE DEEP
SOUTH EARLY NEXT WEEK WHICH MAY ALSO AID IN STORM DEVELOPMENT OVER
THE TN VALLEY, DEPENDING ON ITS TRAJECTORY.

SL.77

&&

.AVIATION...
FOR 12Z TAFS...AN UPPER TROF NOW OVER THE SRN MS RVR VALLEY WILL
BRING THE CHC OF SHRA/TSRA AT BOTH TAF SITES MAINLY BETWEEN 20Z AND
01Z. OTHERWISE IFR/MVFR STRATUS CLOUDS WERE COVERING MOST OF NRN AL
THIS MRNG AND WILL BE SLOW TO DISSIPATE. CONDITIONS SHOULD BECOME VFR
AT KMSL ARND 19Z AND KHSV BY 20Z. VFR CONDITIONS ARE EXPECTED FOR THE
REST OF THE FCST PERIOD...EXCEPT FOR MVFR IN TSRA.

07

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.