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000
FXUS63 KGID 242011
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
311 PM CDT FRI MAY 24 2013

...FCST UNCERTAINTY ABOUNDS THE NEXT SEVERAL DAYS AS THE FCST WILL
HINGE ON OCCURRENCE OF TSTMS SOME OF WHICH COULD BE STG-SVR...

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 311 PM CDT FRI MAY 24 2013

ALOFT: A BLOCKED UPR LOW WILL REMAIN QUASI-STATIONARY OVER THE
PAC NW AND SW CANADA. A LONG-WAVE /LGWV/ RIDGE OVER THE PLAINS
WILL ALSO MOVE LITTLE. THIS COMBINATION WILL MAINTAIN SW FLOW OVER
THE FCST AREA. HOWEVER...THERE ARE NO OBVIOUS SHORT-WAVE /SHRTWV/
TROFS EMBEDDED IN THE FLOW.

SFC: AN OCCLUDED COLD FRONT IS ASSOCIATED WITH THE BLOCKED COLD
CORE LOW. ITS FURTHEST E EXTENT WAS WY INTO NW CO. WHILE HARD TO
FIND ATTM A WARM FRONT WILL BEGIN TO ORGANIZE OVER OR NEAR THE
FCST AREA.

AN EASY FCST THIS IS NOT.

TSTMS ARE A THREAT BUT THERE IS TREMENDOUS UNCERTAINTY IN TIMING
AND LOCATION DUE TO THE LACK OF OBVIOUS SYNOPTIC FORCING.

00Z AND 06Z NAM PERFORMANCE OF 6 HR QPF ENDING 18Z WAS BEST.

AM FAIRLY CONFIDENT THAT TSTMS WILL FORM THIS AFTN/EVNG WITH THE
LEE TROF OVER WRN NEB/ERN CO/NW KS. WHAT HAPPENS TNGT IS UP FOR
GRABS. SOME OF THE HI-RES MODELS INDICATE UP-SCALE GROWTH INTO AN
MCS THAT ROLLS INTO PART OF THE FCST AREA. OTHERS DISSIPATE THE
STORMS.

MCS: NAM/GFS/EC/GEM ALL FCST A 40-50 KT LLJ TNGT WITH ITS NRN
TERMINUS NEAR I-80. THIS WILL RESULT IN STRONG TEMP/MSTR
ADVECTION. AGREE WITH 134 PM WPC QPF DISCUSSION THAT THE GEM AND
UKMET HAVE THE BEST QPF PLACEMENT AT THE NOSE OF THE LLJ. THE NAM
APPEARS WAY TOO LOW AND THE GFS TOO FAR S /RIGHT OVER THE HEART
OF THE FCST AREA/. 12 HR MAX QPF ENDING 12Z/SAT NAILS THE SRN 2/3
OF NEB. SO THE GFS CANT ENTIRELY BE RULED OUT.

I DO NOT WANT TO OVER-FCST TSTMS SINCE MUCH OF THE NEXT 30 HRS
WILL BE DRY FOR MOST OF THE FCST AREA. SO POPS HAVE BEEN TRIMMED
ACKNOWLEDGING THAT I MAY BE TOO LOW...ESPECIALLY 03Z-10Z. I JUST
DONT KNOW WHERE OR WHEN YET. SO WOULD PREFER TO DOWNPLAY TSTM
POTENTIAL...BUT ALL CUSTOMERS SHOULD BE AWARE THAT SUBSTANTIAL
INCREASES IN POPS MAY BE NEEDED IN THE SHORT-TERM FCST UPDATES
THIS EVNG/TNGT AS WE MONITOR HOW THIS EVOLVES. BELIEVE WE HAVE
THE CORRECT POP TREND IN THE HOURLY WX GRAPHS.

BOTTOM LINE...BEST CHANCE APPEARS TO BE ALONG AND N OF I-80 FOR
SOAKING RAINS TNGT AND POSSIBLY SOME SVR HAIL. MUCAPE IS FCST
AROUND 2000 J/KG. 2-7 KM SHEAR OF 20 KTS SUGGESTS MULTICELL
CONVECTIVE MODE. CORFIDI VECTORS SUGGESTS BACK-BUILDING INTO THE
LLJ IS PROBABLE. SO DRENCHING RAINS ARE ON THE TABLE.

REST OF THIS AFTN: A PERIOD OF CLOUDINESS WITH VIRGA AND POSSIBLY
A COUPLE SPRINKLES? OTHERWISE P-M/SUNNY.

TNGT: M/CLEAR TO START BUT LIKELY  ENDS UP M/CLOUDY IF TSTMS
EVOLVE AS EXPECTED. THERE IS A LOW PROBABILITY FOR FOG IF SKIES
CAN CLEAR BEHIND THE DEPARTING STORMS. THE COLD POOL PRODUCED BY
THE RAIN WILL HAVE TO DISRUPT THE SYNOPTIC FLOW TO LIGHTEN THE
WINDS. WE STILL MAY STRATUS TO DEAL WITH.

SAT: IT ALL DEPENDS ON WHAT HAPPENS TNGT. ANY MRNG LEFTOVER RAIN/
TSTMS WILL DEPART...LIKELY LEAVING LOTS OF STRATUS AROUND IN ITS
WAKE. THIS MCS WILL DETERMINE WHERE THE EFFECTIVE WARM FRONT
DEVELOPS WHICH WILL INFLUENCE SUBSEQUENT TSTM ACTIVITY.

EXPECT A SIGNIFICANT DIFF IN TEMPS ACROSS THE FCST AREA AND WE/RE
PROBABLY TOO WARM WHERE STRATUS  LINGERS...FROM TRI-CITIES N AND
E? JUST DONT KNOW YET. BELIEVE THE WARM FRONT WILL SET UP FROM NW-
SE ACROSS THE FCST AREA.

DIFFERENTIAL HEATING...CONVERGENCE ALONG THE  DRYLINE  AND WARM
FRONT WILL ALL BE CAPABLE OF INITIATING TSTMS. HOWEVER...THE WARM
SECTOR LOOKS CAPPED AND AM NOT SURE THERE WILL BE A SHRTWV TROF
TO PROVIDE ENOUGH MID-LVL ASCENT/COOLING.

REGARDLESS...WITH TEMPS 84-88F AND DWPTS IN THE LOW 60S...MLCAPE
IS FCST 3000-4000 J/KG. 0-5 KM SHEAR AROUND 30 KTS WILL BE STRONG
ENOUGH FOR SUPERCELLS IF TSTMS DEVELOP. CELLS NEAR THE WARM FRONT
WILL NEED TO BE MONITORED FOR AN ISOLATED TORNADO.

1730Z DAY 2 SPC OUTLOOK HAS INCLUDED AREAS W OF HWY 183 IN A SLGT
RISK FOR SVR.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 311 CDT FRI MAY 24 2013

AN ACTIVE WEATHER PATTERN REMAINS LIKELY DURING THE LONG TERM
FORECAST PERIOD AS SOUTHWESTERLY  MID TO UPPER LEVEL FLOW
PERSISTS AND MULTIPLE MID LEVEL PERTURBATIONS/SHORTWAVES PUSH
OVER OUR AREA. INCREASED OMEGA AHEAD OF ANY ONE OF THESE MID
LEVEL DISTURBANCES COULD RESULT IN PRECIPITATION ACROSS THE AREA
AND AS A RESULT...POPS CONTINUE IN THE FORECAST FOR EVERY DAY
DURING THE LONG TERM FORECAST PERIOD. QPF FIELDS FROM VARIOUS
MODELS ARE ALL OVER THE PLACE DEPICTING DIFFERING PRECIPITATION
AMOUNTS OVER DIFFERENT AREAS OF THE CWA. SUCH A SITUATION MAKES
IT EXTREMELY DIFFICULT TO PIN DOWN AREAS OF HIGHER CONFIDENCE
WITH RESPECT TO POPS AND AS A RESULT...OPTED TO GO WITH AN EVEN-
AVERAGE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN TO HELP
DERIVE POPS FOR SUNDAY AND MONDAY. BEYOND MONDAY...OPTED TO GO
WITH ALLBLEND WITH MINIMAL CHANGES MADE.

PERSISTENT SOUTH/SOUTHEASTERLY LOW LEVEL FLOW WILL PRESENT
CONTINUED  MOISTURE FLUX INTO THE CENTRAL PLAINS THROUGH MUCH OF
THE LONG TERM FORECAST PERIOD...WITH SURFACE DEWPOINT READINGS
WELL INTO THE 60S EXPECTED ACROSS MUCH OF OUR CWA. THERE ARE
INDICATIONS OF A MEANDERING DRY LINE ACROSS THE WESTERN HALF OF
OUR CWA DURING THE EARLY PART OF NEXT WEEK WHICH...IF
REALIZED...WOULD ALLOW SOME LOCATIONS ACROSS OUR FAR WESTERN CWA
TO OBSERVE A LOWER SURFACE DEWPOINT AT TIMES. AS ALREADY
MENTIONED HOWEVER...CONFIDENCE WITH RESPECT TO THESE DETAILS
REMAINS LOW AND IT IS FAR TOO EARLY TO PRESENT SUCH DETAIL TO
THESE PERIODS OF THE FORECAST.

THE VERY MOIST BOUNDARY LAYER WILL HELP PROMOTE INCREASING
POTENTIAL INSTABILITY DURING THE LONG TERM FORECAST PERIOD...WITH
THE OPERATIONAL GFS AND EC BOTH SUGGESTING DEEP LAYER MUCAPE
VALUES GENERALLY  IN THE 2000-4000J/KG RANGE SUNDAY THROUGH
FRIDAY. IN ADDITION...DEEP LAYER BULK SHEAR VALUES BETWEEN 25KTS
AND 40KTS ARE ALSO EXPECTED EACH DAY. DESPITE THE AFOREMENTIONED
MID LEVEL PERTURBATIONS/SHORT WAVES PUSHING OVER THE AREA DURING
THE LONG TERM FORECAST PERIOD...UNCERTAINTY REMAINS AS TO WHETHER
OMEGA WITH ANY ONE OF THESE FEATURES WILL BE STRONG ENOUGH TO
OVERCOME A LOW LEVEL CAPPING INVERSION EACH DAY. SO WHILE THE
TROPOSPHERE APPEARS AS THOUGH IT WILL BE THERMODYNAMICALLY PRIMED
FOR SIGNIFICANT UPDRAFT PRODUCTION...THERE REMAIN QUESTIONS AS TO
IF AND WHERE CONVECTION WILL ACTUALLY BE REALIZED EACH DAY. GIVEN
ALL THIS...WILL CONTINUE THE VAGUE SEVERE WEATHER MENTION GOING
IN THE HWO FOR THE LONG TERM FORECAST PERIOD.

LITTLE CHANGE IN THE LOW LEVEL AIRMASS WILL PRESENT SIMILAR
TEMPERATURE READINGS EACH DAY DURING THE LONG TERM FORECAST
PERIOD...WITH AN AFTERNOON HIGH TEMPERATURE GENERALLY IN THE 80S
AND AN OVERNIGHT LOW TEMPERATURE IN THE 60S CURRENTLY FORECAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1245 PM CDT FRI MAY 24 2013

REST OF THIS AFTN: VFR CIGS 6-7K FT. THERE IS A LOW PROB FOR A
SHWR OR TSTM. DID NOT INCLUDE IT IN THE TAF AS THE EXACT TIMING
AND OCCURRENCE IS LOW CONFIDENCE. SSE WINDS WILL CONT GUSTING AS
HIGH AS 30 KTS.

TNGT: THERE IS A RISK FOR TSTMS TO MOVE OUT OF WRN NEB AND REACH
THE TERMINAL. THIS IS HIGHLY UNCERTAIN THOUGH. HAVE INDICATED MVFR
STRATUS DEVELOPING AS MSTR INCREASES. IF THIS MATERIALIZES THERE
IS POTENTIAL FOR FURTHER DECAY TO IFR. CURRENT FEELING IS THAT
RAIN MAY NEED TO OCCUR AS A PREREQUISITE. ANY CLEARING BEHIND RAIN
THAT MIGHT OCCUR AND WE COULD HAVE A FOG PROBLEM.

SAT THRU 18Z: IT ALL DEPENDS ON WHAT TRANSPIRES TNGT. IF IFR/MVFR
STRATUS DEVELOPS...EXPECT SLOW IMPROVEMENT BEGINNING 16-17Z.

CIG CONFIDENCE: HIGH THRU 03Z THEN LOW
VSBY CONFIDENCE: HIGH
WIND CONFIDENCE: HIGH
WX CONFIDENCE: MEDIUM


&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

SHORT TERM...HALBLAUB
LONG TERM...BRYANT
AVIATION...HALBLAUB