FXUS63 KABR 311952

AFDABR



AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE ABERDEEN SD

252 PM CDT SAT JUL 31 2010



.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT



A WEAK WAVE EJECTED OUT AHEAD OF THE MAIN LOW OVERN EASTERN MT/WY

IS CAUSING SOME SHOWERS AND TSTORMS ACROSS EXTREME NORTH CENTRAL

SD AND NORTH DAKOTA THIS AFTERNOON. MOST OF THIS CONVECTION IS

RATHER WEAK WITH SOME STRONGER EMBEDDED STORMS. THESE WILL

CONTINUE TO TRACK EAST THIS AFTERNON AND EVENING. THE HRR AND RUC

ARE CAPTURING THIS FAIRLY WELL. TAKING A LOOK AHEAD THE SAME

MODELS DEVELOP A LINE OF STORMS NEAR A DRY LINE THIS EVENING

ACROSS CENTRAL AND SOUTH CENTRAL SOUTH DAKOTA. THE HRR IS SHOWING

POSSIBLE SUPERCELL FORMATION NEAR JONES COUNTY BY 23Z. WILL NEED

TO WATCH THIS SITUATION CAREFULLY OVER THE NEXT FEW HOURS AND SEE

IF THE INITIAL LINE VERIFIES. OTHERWISE ALL OF THIS ENERGY IN THE

PRESENCE OF A STRENGTHENING LLJ WILL GRADUALLY MOVE ACROSS THE

REGION TONIGHT AND INTO SUNDAY MORNING. BY SUNDAY AFTERNOON THE

ATMOSPHERE WILL BECOME CAPPED ENOUGH TO PREVENT MOST TSTORM

DEVELOPMENT UNTIL THE MAIN LOW SWEEPS THROUGH SUNDAY NIGHT. MODELS

HAVE STARTED BACKING OFF A LITTLE ON SEVERE PARAMETERS TOMORROW

EVENING/NIGHT. HOWEVER SPC CONTINUES A SLIGHT RISK OVER THE

REGION. SHEAR REMAINS ELEVATED...BUT THE POSITION OF THE LOW IS

INHIBITING LLJ ENHANCEMENT IN THIS CWA. STEEP LAPSE RATES COUPLED

WITH HIGH SHEAR AND A MOIST ENVIRONMENT STILL SET THE STAGE FOR

SOME LARGE HAIL POTENTIAL BEFORE THE SYSTEM BECOMES AN MCS ON

MONDAY OVER SOUTHEAST SD. DID NOT ADD SEVERE YET TO THE GRIDS BUT

MAY NEED TO DO SO WITH NEXT PRODUCT ISSUANCE.



TEMPERATURES WILL BE VERY WARM THROUGH THE WEEKEND...WITH 80S AND

90S FOR HIGHS. THE WESTERN CWA WILL BE WELL INTO THE 90S ON SUNDAY

AS THERMAL RIDGE POKES NORTHWARD INTO THE REGION AHEAD OF THE

APPROACHING COLD FRONT. 850MB TEMPS APPROACH +30 C OVER THE

WESTERN CWA BY SUNDAY AFTERNOON.









.LONG TERM...12Z TUESDAY THROUGH SATURDAY.

MAIN FCST CHALLENGE FACING THE LONG TERM REVOLVES AROUND PCPN

POTENTIAL. 



MODELS CONTINUE TO ADVERTISE A QUICK-MOVING QUASI-ZONAL FLOW

REGIME SETTING UP ACROSS THE UPPER MIDWEST. FAST MOVING 500HPA AND

700HPA VORTS MOVE QUICKLY THROUGH. GETTING A FIRM GRASP ON WHICH

WAVE WILL SPARK TSRA AT A GIVEN MOMENT IN TIME IS TROUBLESOME AT

BEST AND NEARLY IMPOSSIBLE AT WORST. HOWEVER...AS TIME

PROGRESSES...GULF STATES 500HPA RIDGE BUILDS EVER SO

SLIGHTLY..WITH DEEPENING PAC NW TROF...SO THAT BY THE END OF THE

EXTENDED...THE REGION MOVES FROM ZONAL TO SW FLOW...ENSURING A BIT

BETTER PROBABILITY OF TSRA DEVELOPMENT LATER IN THE PERIOD. 



MODELS DIFFER ON STRENGTH/TIMING AND POSN OF WAA FORCING...AS SEEN

IN THE 700HPA THETA-E FIELDS...BUT THEY DO AGREE WITH GIVEN THE NW

700HPA FLOW EARLY IN THE EXTENDED...CAPPING TEMPS DON'T POSE AN

ISSUE. BY FRIDAY...BUILDING 500HPA/700HPA RIDGE ALLOW WARMER TEMPS

ALOFT TO ADVECT IN. ANOTHER FACTOR THAT COMES INTO PLAY IS

MOISTURE RETURN. THE GFS INDICATES THAT A FAIRLY STRONG COMPLEX

MAY SET UP ACROSS SRN NEB LATE THURSDAY INTO FRIDAY...PREVENTING

ANY FURTHER NORTHWARD ADVECTION OF MOISTURE. 



WITH RATHER LOW CONFIDENCE IN ANY ONE PARTICULAR MODEL RUN...HAVE

OPTED TO GO WITH A CLIMATOLOGICAL TREND TOWARD PCPN...HAVING CHCS

OUT WEST BY LATE AFTERNOON...BRINGING EAST AFT 00Z...THEN

LINGERING ACROSS THE FAR EAST THROUGH 18Z THE NEXT DAY. THEN

MECHANISM RESETS AS NEXT QUICK MOVING WAVE IMPACTS CWA. 



TEMP WISE...PRETTY MUCH RAN WITH INHERITED MAX/MIN TEMPS. DID

NUDGE UP DWPTS JUST A BIT GIVEN NATURE OF SOGGY SOILS ACROSS THE

SRN PART OF THE STATE AND EXPECTED SOUTHERLY BEING ABLE TO PUSH

SOME OF THAT NORTHWARD. 







&&



.AVIATION...

18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS



BOUNDARY DRAPED ACROSS THE ND/SD BORDER AT 20Z WILL BE THE FOCUS

FOR TSRA DEVELOPMENT LATER THIS EVENING AND OVERNIGHT. VCTS IS

PSBL FOR KPIR/KMBG AND KABR TERMINALS THROUGH 10Z. VFR CIGS ARE

STILL EXPECTED FOR KPIR/KMBG AND KABR...ALTHO ISOLD MVFR VSBYS

COULD BE POSSIBLE WITH HEAVIER SHOWERS. KATY WILL HAVE NO WEATHER

IMPACTS THROUH 12Z SUNDAY.







&&



.ABR WATCHES/WARNINGS/ADVISORIES...

SD...NONE.

MN...NONE.

&&



$$

SHORT TERM...WISE

LONG TERM...HINTZ

AVIATION...HINTZ



WEATHER.GOV/ABERDEEN