Severe Thunderstorm Warning 279, NWS Little Rock, AR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LITTLE ROCK AR
114 PM CDT FRI AUG 23 2002

12Z MODELS YESTERDAY TURNED OUT TO BE AN ABERRATION INSTEAD OF A
SIGNIFICANT TREND. THE CONSENSUS...PARTICULARLY AMONG THE SPECTRAL
MODELS...HAS RETURNED TO PUSHING THE FRONT COMPLETELY THROUGH OUR
CWFA OVER THE WEEKEND WITH DRIER AIR BEHIND IT.

THE MOST RECENT MESOETA STILL BRINGS THE FRONT INTO OUR NORTHERN
ZONES SATURDAY AFTERNOON...STALLS IT IN THE CENTRAL ZONES UNTIL
SUNDAY MORNING...AND WASHES IT OUT BY SUNDAY AFTERNOON. THE AVN IS
SIMILAR TO THIS SOLUTION THROUGH SUNDAY MORNING...BUT THEN BRINGS
THE FRONT ENTIRELY THROUGH THE CWFA BY SUNDAY AFTERNOON AS A STRONG
VORT MAX SLIDES DOWN FROM THE NORTHWEST AND AMPLIFIES THE UPPER
FLOW. THE CANADIAN IS A NICE COMPROMISE...STALLING THE FRONT A
LITTLE LONGER BEFORE IT MAKES ITS FINAL PUSH THROUGH OUR SOUTHERN
ZONES SUNDAY EVENING. STILL AWAITING THE 12Z NOGAPS AS ACCESS TO THE
FNMOC WEB SITE SEEMS UNUSUALLY SLOW TODAY.

REVERTING BACK TO THE SHORT TERM FOR A MOMENT...SCATTERED
THUNDERSTORMS WERE DEVELOPING THIS AFTERNOON ALONG A MOISTURE
DISCONTINUITY WHICH WAS APPARENT ON VISIBLE SATELLITE IMAGERY BUT
NOT EASILY DISCERNIBLE IN THE MORNING UPPER AIR DATA OR SURFACE OBS.
THESE STORMS WILL AGAIN WEAKEN AFTER SUNSET...AND NO ADDITIONAL
DEVELOPMENT IS EXPECTED OVERNIGHT. ISOLATED TO WIDELY SCATTERED
AFTERNOON STORMS ARE EXPECTED AGAIN SATURDAY. SATURDAY NIGHT...THE
REMNANTS OF A MESOSCALE CONVECTIVE SYSTEM ARE EXPECTED TO MOVE
SOUTHEAST INTO ROUGHLY THE NORTHERN HALF OF OUR CWFA. THERE IS A
GOOD BIT OF MODEL AGREEMENT ON THE EXISTENCE OF THIS MCS...SHOWN
THROUGH BOTH EXPLICIT PRECIP FORECASTS AND CONVECTIVE FEEDBACK.
TIMING IS A PROBLEM...WITH THE AVN SEEMING TOO FAST WITH THE LEADING
VORT MAX AND THE ETA TOO SLOW. A COMPROMISE WILL BE STRUCK FOR THIS
PACKAGE. AS THIS SYSTEM MOVES THROUGH...IT WILL PUSH THE EFFECTIVE
FRONT FARTHER SOUTH VIA CONVECTIVE EFFECTS AND IT WILL ALSO USE UP
MUCH OF THE ENERGY IN THE AIRMASS. THUS...AFTERNOON STORMS WILL BE
UNLIKELY ON SUNDAY IN AREAS WHERE THE MCS PASSES THROUGH IN THE
MORNING...WITH DEVELOPMENT MORE LIKELY FARTHER SOUTH ALONG THE
EFFECTIVE FRONT AND OUTFLOW BOUNDARIES. TEMPERATURES WILL BE
PROBLEMATIC AS IT IS DIFFICULT TO TELL WHETHER THERE WILL BE PLENTY
OF SUNSHINE IN THE WAKE OF THE MCS OR LEFTOVER CLOUDS.

THE NEW WORK WEEK BEGINS WITH A FORECAST WHICH REMAINS UNCERTAIN.
THE AVN SHOWS A DEEPER UPPER LOW THAN THE ETAX OVER THE SOUTHEASTERN
STATES...LEADING TO STRONGER NORTHERLY FLOW AND DRIER AIR IN PLACE.
AVN SUGGEST SLIGHT PRECIP CHANCES WOULD BE CONFINED TO THE EASTERN
ZONES...WHILE THE ETAX TARGETS THE SOUTHWEST. 00Z CANADIAN SHOWS
LIGHT PRECIP AREAWIDE. WILL LEAVE SLIGHT CHANCE AREAWIDE FOR NOW AND
TRY TO PIN DOWN THIS ISSUE TOMORROW. IF AVN/CANADIAN SOLUTIONS PAN
OUT...TUESDAY AND WEDNESDAY WOULD BE DRY AS THE UPPER LOW SLUGGISHLY
LIFTS AWAY TO THE NORTHEAST. 00Z AVNX SHOWS A TROUGH PASSING BY
THURSDAY AND FRIDAY...SO SLIGHT CHANCE POPS WILL CONTINUE FOR THOSE
DAYS. IT IS WORTH NOTING THAT THE 12Z AVN IS SLOWER TO MOVE THE
UPPER LOW OUT OF THE SOUTHEASTERN STATES THAN THE 00Z AVNX...SO IF
THIS TREND CONTINUES...THE NEXT CHANCE OF RAIN MAY HOLD OFF UNTIL
AFTER THURSDAY.

PRELIMINARY NUMBERS...SUBJECT TO CHANGE...ESPECIALLY FIRST PERIOD...

LIT 73 94 73 90 70 / 20 20 40 40
HOT 74 96 74 92 69 / 20 20 40 40
HRO 71 88 67 86 65 / 20 30 60 30
PBF 73 94 73 92 71 / 20 20 30 50

.LZK...NONE.

54